text stringlengths 454 608k | url stringlengths 17 896 | dump stringclasses 91
values | source stringclasses 1
value | word_count int64 101 114k | flesch_reading_ease float64 50 104 |
|---|---|---|---|---|---|
One of you guys asked me to do a tutorial on Fixing Java Errors. I thought it was a good idea, so here I’ll show you over 30 common Java errors.
Sometimes it is hard to figure out what Cannot be Resolved, Syntax Error on Token, or Method is not Visible mean. But, after watching this video you should better understand.
Also, you’ll learn how to get Eclipse to help you fix Java errors.
If you like videos like this tell Google [googleplusone]
To make me extra happy, feel free to share it
Code from the Video
import java.lang.Math.*; public class Lesson35{ // ERROR 1: Cannot make a static reference to the non-static method // SOLVED: You can't call a non static method from a static method // private void printSomething(){ private static void printSomething(){ // ERROR 2: Unresolved compilation problem // SOLVED: Pay attention to Eclipse Errors // Int BigNumber = 100000; // ERROR 3: A string literal isn't properly closed // SOLVED: Pay attention to Eclipse //String something = "A string error //is occurring"; System.out.println("Something"); } // If this is missing you get ERROR 2 // ERROR 4: Exception in thread "main" java.lang.NoSuchMethodError: main // SOLVED: Make sure you type the main function correctly // public static void main(String args){ // This is Wrong public static void main(String[] args){ // ERROR 5: Can't be resolved to a variable // SOLVED: Pay attention to Eclipse // printsomething; // This is Wrong printSomething(); // ERROR 6: Type mismatch Can't convert from int to String // SOLVED: Convert the integer int number = 12; // String anotherNum = number; // This is Wrong String anotherNum = Integer.toString(number); // int number = Integer.parseInt(anotherNum); // Convert from string to int // ERROR 7: Can't be resolved to a type // SOLVED: import the dimension library // Dimension dim = new Dimension(); // ERROR 8: Method is undefined // SOLVED: Make sure methods are in the class double pi = 3.14; // long randLong = Lesson34.round(pi); // The wrong way // ERROR 9: Can't invoke method // SOLVED: Understand how methods work long randLong = Math.round(pi); // The right way // randLong = pi.round(); // Wrong way // ERROR 11: The method is not applicable for the arguments // SOLVED: Provide the right arguments in the right order // getStuff(1.234, 5); // Wrong Way getStuff(1,5.0); // Right Way // ERROR 12: Syntax error on token ",; expected // SOLVED: Understand how methods are called in Java vs. other languages // double sumNum = addThem(LessonFive,1,2); // Wrong Way double sumNum = LessonFive.addThem(1,2); // ERROR 13: Syntax error on token '==' // SOLVED: = is different from == // int value == 1; } // ERROR 10: Can't be resolved to a type // SOLVED: Always provide the type in methods /* public static void getStuff(number1, number2){ } */ // ERROR 14: Return type for method is missing // SOLVED: Provide a return type or void public static void getStuff(int number1, double number2){ // ERROR 15: Syntax error on token ",[ expected // SOLVED: Understand how arrays are defined in Java // int[] intArray = new [10,10]int; // Wrong Way int[][] intArray = new int[10][10]; // ERROR 16: The method is not visible // SOLVED: You can't private methods which are declared in // another class. private static void getFileInfo() // Lesson33.getFileInfo(); // Wrong Way // ERROR 17: Local variable may not have been initialized // SOLVED: Always give variables default values String howMany = "10"; // String howMany; // Wrong Way System.out.println(howMany); // ERROR 18: Cannot be Resolved // SOLVED: Understand that arrays and strings use a // different version of length System.out.println(howMany.length()); // System.out.println(howMany.length); // Wrong Way // System.out.println(intArray.length()); // Wrong Way System.out.println(intArray.length); // ERROR 19: Prefix Operator vs. Postfix Operator int xInt = 1, yInt = 1; xInt = yInt++; // Passes the original value of yInt before incrementing System.out.println("xInt: " + xInt); // ERROR 20: Not calling break at end of case int day = 1; switch (day){ case 1: System.out.println("Monday"); case 2: System.out.println("Tuesday"); case 3: System.out.println("Wednesday"); case 4: System.out.println("Thursday"); default: System.out.println("Friday"); } } }
thanks for the tutorial, will u pls also make a tutorial on IE errors and how to fix it?
I covered a great deal about making cross browser sites in How to Design a Website.
Thanks , i got it. i have got some new issues , pls help me to understand when you are free.
1. position property can be used to set the position of an element, so why float is important to learn ? is it true that using position property is a bad practice when we have chance to use float property ?
2. suppose there are two class named “something” and “nothing”,
wht is difference between .something+.nothing{property:value;} and .something, .nothing {property:value;}?
as far as i know this .something, .nothing {property:value;} is called Grouping Selectors.
3. display:inline-block; what does it mean ?
4. would u please give me a practical example of display:block property ?
i know u are a css geek but very helpful, so i have asked a lot , dont mind, take care
1. I like to use float to get all of the page elements to wrap around it. I don’t like to use absolute positioning. I just think a more liquid layout looks better. That is just an opinion.
2. #idName.className would target an element with both a class name and id name. When you put a space between these you are targeting elements under the first element. So, #idName .className means target all elements with the class name className that are decendents of idName
3. inline-block doesn’t force line breaks after the element. Since it is still a block item you can set width, height, top and bottom margins / paddings
4. block elements force a line break and allow you to define width, height, top and bottom margins / paddings
Thank you so much , u R the best and friendly tutor i have ever seen.
You’re very welcome. I do my best
pls i want tutorial on how to deploy a java application and a print method for printing screens in a printer
I’ll cover printing. It is very easy to set up. I’m not done with Java yet
Hello Derek,
Please let me know,
What is java-jni priority in your priority list?
You are jumping in every possible technology(SAMSUNG SDK), I want you to come back to our old C / C++ sooooooooooon!!
I was able to reach till java # 35 now, with all your programs written and compiled.
I’m going to finish Samsung this month. Then I’ll finish up C, Inkscape, Google Maps with Android and a few other Android technologies. At that point I’ll transition into Android graphics, interfaces and games. I’ll hold a vote on whether the tutorial that will come out along with the Android stuff will be C++, or J2EE. | http://www.newthinktank.com/2012/04/java-video-tutorial-35/?replytocom=8973 | CC-MAIN-2019-51 | refinedweb | 1,136 | 63.39 |
There are two different methods of transmitting USB data between your microcontroller board and your PC. They are called "USB Stacks". They are layers of code that handle all of the protocols for transmitting data whether you are using it to upload your program to the board, receiving data via the serial monitor or serial plotter, or talking back to your computer emulating a mouse, keyboard or other device.
Traditional Arduino 8-bit boards all use the original Arduino stack. Newer boards such as M0 and M4 based on the SAMD21 and SAMD51 have the option of using either the Arduino stack or a different version called the TinyUSB Stack. Still other boards such as the nRF52840 based boards use only TinyUSB and it is likely that upcoming boards such as the ESP32-S2 will continue to use only TinyUSB. This is primarily because TinyUSB is the underlying architecture for implementing CircuitPython on these boards.
If you are using an M0 or M4 board you select which stack you want to use in the Tools menu of the Arduino IDE as shown below.
The image shows the tools menu of the Arduino IDE and we have selected an Adafruit Feather M0 Express board. Here you have a choice between using the Arduino stack or the TinyUSB stack.
However in the image below, we have configured for an Adafruit Feather nRF52840 Express. As you can see there is no "USB Stack" option. What you cannot see is that this particular board only uses TinyUSB. If you try to #include it will not find the proper library because is not supported under TinyUSB.
For the M0 and M4 boards you can simply choose to select the Arduino stack and there's no problem. However the TinyUSB stack also has many other features that might be useful to you. Among them are the ability to use WebUSB and to use the onboard flash chip of your board as a mass storage device. This essentially turns your Feather board into a flash drive where you can drag-and-drop files. We will not be covering those capabilities in this tutorial. Of course if you're using the nRF52840 based systems don't have a choice. You have to use TinyUSB.
As mentioned previously, the traditional way to control mouse or keyboard is the following include files.
#include <HID.h> #include <Mouse.h> #include <Keyboard.h>
#include <HID.h> #include <Mouse.h> #include <Keyboard.h>
You should erase those lines and replace them with
#include <TinyUSB_Mouse_and_Keyboard.h>
#include <TinyUSB_Mouse_and_Keyboard.h>
This will automatically detect whether you are using the Arduino Stack or the TinyUSB Stack. If you are using the original Arduino Stack it will simply do the necessary include files for you. And if you're using TinyUSB Stack it will instead use its own code that works exactly like the originals. Note that there is no way to separate Mouse and Keyboard inclusion in our system. It was much easier to implement both at once rather than implementing them separately because of the way TinyUSB implements its HID functions. Theoretically when you compile your code if you did not make any reference to Keyboard and only to Mouse the linking loader will eliminate the Keyboard code. And vice versa if you use only Keyboard and not Mouse. Combining these into a single library saved us a lot of headaches.
If you have existing code that uses Mouse.h or Keyboard.h or both you should make the changes noted above and give it a try.
If you are using an M0 or M4 based board, you will have to set the Tools->USB Stack to "TinyUSB". In fact try switching back and forth between the two stacks and recompiling. You should see the same results using either stack. If you are using the nRF52840 processor, you do not need to select the TinyUSB option.
While developing and testing this library, we discovered that occasionally it makes a difference when you call the
Mouse.begin() or
Keyboard.begin() methods relative to the
Serial.begin(…) method. Sometimes your computer would get confused as to how your USB was operating. Was it a mouse? Was it a keyboard? Was it a serial device? We had inconsistent results. Our best results came if you did your
Mouse.begin() and/or
Keyboard.begin() before doing
Serial.begin(…). No such restriction is necessary when using the BLE52 version of the library. It only affects the TinyUSB version.
In the next section, we will describe the BLE52 library followed by a series of three demonstration examples. | https://learn.adafruit.com/mouse-and-keyboard-control-using-tinyusb-and-ble/tinyusb-mouse-and-keyboard-usage | CC-MAIN-2021-21 | refinedweb | 766 | 66.94 |
Debugger Views Application Sample
This sample demonstrates a feature introduced with Microsoft Visual Studio 2005, the capability to change the way you view a class in the debug windows. By applying new attributes such as the DebuggerDisplayAttribute to a class and its members, you can control how the value, type, and name columns are displayed for that type in the Locals debug window, and whether a value is shown, hidden, or expanded when viewed. This sample is currently available only in Microsoft Visual C# 2005.
For information about using the samples, see the following topics:
This sample includes source files for three classes that contain the debugger attributes and source files that do not, as shown in the following table.
The DebuggerViewsExample.cs file contains the entry point of the console application and is used by both sets of files. Uncomment the code in the debug versions (DebugAddress.cs, DebugCustomer.cs, and DebugCustomerName.cs) to run the sample.
To build the sample using the Command Prompt
Open a Command Prompt window and navigate to the \CS subdirectory under the DebuggerViewsCS directory. For information about required settings and the SDK Command Prompt, see How to: Set Sample Settings.
Type msbuild DebuggerViewsCS.sln at the command line.
To build the sample using Visual Studio
Open Windows Explorer and navigate to the \CS subdirectory under the DebuggerViewsCS directory.
Double-click DebuggerViewsCS.sln to open the file in Visual Studio 2005.
On the Build menu, click Build Solution.
To run the sample
On the View menu of Visual Studio, click Solution Explorer.
In the Solution Explorer window, double-click DebuggerViewsExample.cs to open the file in Visual Studio 2005.
On the Project menu, click Show all files.
Insert a breakpoint (press F9) on the line where the GetCustomers method instantiates a variable of type Customer, as shown here:
Customer c = new Customer(cn, Address.GetAddressById(customerAddresses, cn.Id));
Press F5 to start and run the sample application in the Visual Studio 2005 debugging environment.
When the application breaks at the breakpoint, press F10 to step to the next line of code.
Observe current values in the Locals window by expanding the hierarchy of the application's properties, collections, and other objects. To display the Locals window, click Windows from the Debug menu and then click Locals.
On the Debug menu, click Stop Debugging, press Shift+F5, or click the icon in the Debugging toolbar, to stop code execution.
Uncomment the code in the three files whose names start with Debug. Then comment out the code in the three files whose names start with NonDebug, or select those three files in the Solution Explorer window, right-click, and then click Exclude From Project.
On the Debug menu, choose Start with the same breakpoint set. When the application breaks, observe the details in the Locals window values column, which now has additional information provided by debugging attributes.
To provide an example of using a debugging attribute, the DebugCustomer.cs file contains the following DebuggerDisplay attribute for the CustomerName class:
[DebuggerDisplay("{(FirstName == null) ? \"\":FirstName} {LastName} ==> (Customer ID = {Id})")]
DebuggerTypeProxy(typeof(CustomerNameDebugView))]
public class CustomerName
When debugging, this attribute displays the following value in the Locals window. The name cn is an instance of a CustomerName object.
Without the attribute, the Locals window displays the following: | https://msdn.microsoft.com/en-us/library/k7deak79(v=vs.90).aspx | CC-MAIN-2018-13 | refinedweb | 548 | 55.74 |
/* * mutex.h * * Mutual exclusion thread synchon.14 2005/11/25 00:06:12 csoutheren * Applied patch #1364593 from Hannes Friederich * Also changed so PTimesMutex is no longer descended from PSemaphore on * non-Windows platforms * * Revision 1.13 2005/11/08 22:31:00 csoutheren * Moved declaration of PMutex * * Revision 1.12 2005/11/08 22:18:31 csoutheren * Changed PMutex to use PTimedMutex on non-Windows platforms because * sem_wait is not recursive. Very sad. * Thanks to Frederic Heem for finding this problem * * Revision 1.11 2005/11/04 06:34:20.10 2003/09/17 05:41:58 csoutheren * Removed recursive includes * * Revision 1.9 2003/09/17 01:18:02 csoutheren * Removed recursive include file system and removed all references * to deprecated coooperative threading support * * Revision 1.8 2002/09/16 01:08:59 robertj * Added #define so can select if #pragma interface/implementation is used on * platform basis (eg MacOS) rather than compiler, thanks Robert Monaghan. * * Revision 1.7 2002/01/23 04:26:36 craigs * Added copy constructors for PSemaphore, PMutex and PSyncPoint to allow * use of default copy constructors for objects containing instances of * these classes * * Revision 1.6 2001/05/22 12:49:32 robertj * Did some seriously wierd rewrite of platform headers to eliminate the * stupid GNU compiler warning about braces not matching. * * Revision 1.5 1999/03/09 02:59:50 robertj * Changed comments to doc++ compatible documentation. * * Revision 1.4 1999/02/16 08:12:22 robertj * MSVC 6.0 compatibility changes. * * Revision 1.3 1998/11/30 02:50:59 robertj * New directory structure * * Revision 1.2 1998/09/23 06:20:55 robertj * Added open source copyright license. * * Revision 1.1 1998/03/23 02:41:31 robertj * Initial revision * */ #ifndef _PMUTEX #define _PMUTEX #ifdef P_USE_PRAGMA #pragma interface #endif #include <ptlib/critsec.h> #include <ptlib/semaphor.h> /**This class defines a thread mutual exclusion object. A mutex is where a piece of code or data cannot be accessed by more than one thread at a time. To prevent this the PMutex is used in the following manner: \begin{verbatim} PMutex mutex; ... mutex.Wait(); ... critical section - only one thread at a time here. mutex.Signal(); ... \end{verbatim} The first thread will pass through the #Wait()# function, a second thread will block on that function until the first calls the #Signal()# function, releasing the second thread. */ /* * On Windows, It is convenient for PTimedMutex to be an ancestor of PSemaphore * But that is the only platform where it is - every other platform (i.e. Unix) * uses different constructs for these objects, so there is no need for a PTimedMute * to carry around all of the PSemaphore members */ #ifdef _WIN32 class PTimedMutex : public PSemaphore { PCLASSINFO(PTimedMutex, PSemaphore); #else 00131 class PTimedMutex : public PSync { PCLASSINFO(PTimedMutex, PSync) #endif public: /* Create a new mutex. Initially the mutex will not be "set", so the first call to Wait() will never wait. */ PTimedMutex(); PTimedMutex(const PTimedMutex & mutex); // Include platform dependent part of class #ifdef _WIN32 #include "msos/ptlib/mutex.h" #else #include "unix/ptlib/mutex.h" #endif }; // On Windows, critical sections are recursive and so we can use them for mutexes // The only Posix mutex that is recursive is pthread_mutex, so we have to use that #ifdef _WIN32 typedef PCriticalSection PMutex; #else typedef PTimedMutex PMutex; #endif #endif // End Of File /////////////////////////////////////////////////////////////// | http://pwlib.sourcearchive.com/documentation/1.10.0/mutex_8h-source.html | CC-MAIN-2018-13 | refinedweb | 552 | 55.44 |
Bokeh is a Python package that helps in data visualization. It is an open source project. Bokeh renders its plot using HTML and JavaScript. This indicates that it is useful while working with web-based dashboards.
Bokeh can be easily used in conjunction with NumPy, Pandas, and other Python packages. It can be used to produce interactive plots, dashboards, and so on. It helps in communicating the quantitative insights to the audience effectively.
from bokeh.plotting import figure, output_file, show xs = [[5, 6, 9], [2,3,6], [4, 3, 7, 1]] ys = [[6, 5, 8], [3,0,8], [2, 3, 6, 8]] fig = figure(plot_width = 400, plot_height = 200) fig.patches(xs, ys, fill_color = ['red', 'blue', 'green'], line_color = 'white') output_file('patchplot.html') show(fig)
The required packages are imported, and aliased.
The figure function is called.
The ‘output_file’ function is called to mention the name of the html file that will be generated.
The data is defined as a list of lists.
The width and height of the plot are defined within the ‘figure’ function.
The ‘patches’ function present in Bokeh is called.
The ‘show’ function is used to display the plot. | https://www.tutorialspoint.com/how-can-patch-plot-with-multiple-patches-be-visualized-in-bokeh | CC-MAIN-2021-31 | refinedweb | 191 | 68.57 |
Monday Motivation Hack: Use Your PTO
You think you’re locking in your career by never missing a day.
You’re not alone.
Research shows that more than a quarter of workers fear that taking time off will make them seem less dedicated. Others think that vacation-time martyrdom will boost their chances for a raise or a promotion (it doesn’t).
But, this (very American) cultural phenomenon of rarely taking time off and almost never using all of one’s vacation days is bad news for employers and employees alike. And managers know it.
According to Project: Time Off, managers agree that paid time off (PTO):
- improves health and well-being (82 percent)
- relieves burnout (81 percent)
- increases employees’ focus after return (78 percent)
- improves employees’ commitment to their jobs (70 percent)
So, if the boss is on board, why did Americans donate 658 million vacation days to their employers in 2015?
More than 66 percent of employees report getting mixed or negative messages about time off and just don’t want to take the risk, deal with the stress, or let the work build up.
However, there are important reasons to make PTO a priority.
Why You Absolutely Must Start Using Your PTO
Recently, we explored the benefits of self-care and treating yo’self for motivation and productivity. Using up your PTO takes these ideas to the next level, and the benefits are just as profound.
- Vacation can save your life—literally. Research shows that high-risk middle-aged men who took regular vacations were less likely to die of all causes and significantly less likely to die of heart attack during the course of a nine-year study. Vacation has also been shown to have an effect on your body and mind similar to that of meditation.
- Time off is critical to self-care, creativity, and motivation. Though research shows the halo-effect of vacation is short lived, it is a vital part of recharging your batteries and your willpower.
How to Get the Most from Your PTO
Put a little excitement in this Monday, and do these things today:
- Find out how many vacation days you currently have.(Check with HR if you have questions about how or when you need to use PTO.)
- Mark out paid holidays on your calendar.
- Pick three fun things you could do with the vacation time you have.
When you have an idea of what you’re working with, there are a few best practices that will set you up for success when you do take time off.
Plan ahead.
Planning is highly correlated with increased use of time off. Many people fear the amount of backed-up work they’ll come back to if they take time off. By wrangling your workload effectively, you will be able to build in adequate buffers to your vacation time and remove the stress that can accompany time off.
Plan around slow seasons.
Take advantage of lulls in your industry to minimize backlogged work before and after vacation.
Piggy-back on holidays.
A lot of people take vacation whenever they can squeeze it in. By planning, you are able to optimize not only workflows but also total time off, getting the maximum bang for your days-off buck.
Communicate with your team.
Advanced notice to your team—with regular reminders—works wonders. You can set early deadlines, and your colleagues will often cooperate to make project requests farther in advance so you’re not bottlenecked before or after your time off.
Make vacation planning a reward.
By planning far-ish in advance for PTO, you get to look forward to your coming vacation. It’s fun to see the details come together. Plus, on rough days, it can be highly motivating to have something concrete to look forward to/daydream about.
Now that you know how much time off you have, when some good times to go on vacation are, and how you’re going to plan for that time, let go of the worry that your boss will be angry or that you’ll fall behind, and plan a trip!
How much vacation do you take? How do you prepare for it and what tips would you share?
| https://www.grammarly.com/blog/monday-motivation-hack-use-pto/ | CC-MAIN-2018-26 | refinedweb | 707 | 70.73 |
Debugging QML Applications
Console API
Log
console.log, console.debug, console.info, console.warn and console.error can be used to print debugging information to the console. For example:
function f(a, b) { console.log("a is ", a, "b is ", b); }
The output is generated using the qDebug, qWarning, qCritical methods in C++ (see also Debugging Techniques).
Assert
console.assert tests that an expression is true. If not, it will write an optional message to the console and print the stack trace.
function f() { var x = 12 console.assert(x == 12, "This will pass"); console.assert(x > 12, "This will fail"); }
Timer
console.time and console.timeEnd log the time (in milliseconds) that was spent between the calls. Both take a string argument that identifies the measurement. For example:
function f() { console.time("wholeFunction"); console.time("firstPart"); // first part console.timeEnd("firstPart"); // second part console.timeEnd("wholeFunction"); }
Trace
console.trace prints the stack trace of the JavaScript execution at the point where it was called. The stack trace info contains the function name, file name, line number and column number. The stack trace is limited to last 10 stack frames.
Count
console.count prints the current number of times a particular piece of code has been executed, along with a message. That is,
function f() { console.count("f called"); }
will print
f called: 1,
f called: 2 ... whenever
f() is executed.
Profile
console.profile turns on the QML and JavaScript profilers. Nested calls are not supported and a warning will be printed to the console.
console.profileEnd turns off the QML and JavaScript profilers. Calling this function without a previous call to console.profile will print a warning to the console. A profiling client should have been attached before this call to receive and store the profiling data. For example:
function f() { console.profile(); //Call some function that needs to be profiled. //Ensure that a client is attached before ending //the profiling session. console.profileEnd(); }
Exception
console.exception prints an error message together with the stack trace of JavaScript execution at the point where it is called.
Debugging Module Imports
The
QML_IMPORT_TRACE environment variable can be set to enable debug output from QML's import loading mechanisms.
For example, for a simple QML file like this:
import QtQuick 2.3 Rectangle { width: 100; height: 100 }
If you set
QML_IMPORT_TRACE=1 before running the QML Scene (or your QML C++ application), you will see output similar to.
Enabling the Infrastructure
You have to explicitly enable the debugging infrastructure when compiling your application. If you use qmake, you can add the configuration parameters to the project .pro file:
- Qt Quick 1:
CONFIG+=declarative_debug
- Qt Quick 2:
CONFIG+=qml_debug
If you use some other build system, you can pass the following defines to the compiler:
- Qt Quick 1:
QT_DECLARATIVE_DEBUG
- Qt Quick 2:
QT_QML_DEBUG
Note: Enabling the debugging infrastructure might compromise the integrity of the application and system, and therefore, you should only enable it in a controlled environment. When the infrastructure is enabled, the application displays the following warning:
QML debugging is enabled. Only use this in a safe environment.
Starting Applications
Start the application with the following arguments:
-qmljsdebugger=port:<port_from>[,port_to][,host:<ip address>][,block]
Where
port_from (mandatory) specifies either the debugging port or the start port of a range of ports when
port_to is specified,
ip address (optional) specifies the IP address of the host where the application is running, and
block (optional) prevents the application from running until the debug client connects to the server. This enables debugging from the start.
After the application has successfully started, it displays the following message:
QML Debugger: Waiting for connection on port <port_number>
Connecting to Applications
When the application is running, an IDE or a tool that implements the binary protocol can connect to the open port.
Qt provides a
qmlprofiler command line tool to capture profiling data in a file. To run JS, inspecting the object tree, and profiling the activities of a QML engine. For more information, see Qt Creator: Debugging Qt Quick. | https://doc.qt.io/archives/qt-5.5/qtquick-debugging.html | CC-MAIN-2021-39 | refinedweb | 673 | 50.02 |
DNS configuration for single server LAN
Point your clients to your local dns server. Setup your dns server to "forward" to your isp's server.
DNS configuration for single server LAN
My DNS server is my one and only domain controller. As such, its start of authority begins at the root leve, which means it cannot be configured for forwarding. If there is a way to actually implement your idea, feel free to explain: I'll try itand award the points to you if it works.
DNS configuration for single server LAN
Hi Todd,
their are two Methods of configuring DNS for your office. The first Method is, like you set it up, the user has to know only one namespace for intra and internet use. This method is extremly heavy to administer, you must configure your firewall espically so no dns traffic from inside goes to outside, since your using the offical root-level Domain and your not registred.
The other method is much simpler to administer, but the user had to recognize two diffrent Namespaces. Create a new Zonefile naming like .INTR for your intranet and configure the forwarder, an DNS-Server from your ISP. Create a Domain you like MYOFFICE, so your DNS looks like MYoffice.intr .
regards
Frobo
DNS configuration for single server LAN
I am probably missing something, but, as I mentioned in response to the first suggestion, I am unable to set forwarding on the DNS service because is has root level authority. I think I need a little more detail to understand how to make use of yoursuggestion. Can you point me to any information on splitting up the zone so that my DNS server does not have root level authority, which it has by default, so I can try the rest of your idea? I know next to nothing about configuring zones of authority. Thanks.
DNS configuration for single server LAN
DHCP does not play well with NAT i would recommend you disable it on your router then follow te first post
DNS configuration for single server LAN
DHCP is important on a network with downlevel clients because it works with the DNS server to populate the WINS table automatically. It also makes management of the network much easier. I have it working just fine behind my firewall/router, which is performing NAT.
DNS configuration for single server LAN
I have setup primary domains on my NT-4 Server/Microsoft DNS Server system for my local network. On the first screen of DNS Manager add your server, create a new domain, then create a new reverse domain (333.222.111.in-addr.arpa). Go to the forwarddomain and enter your hosts making sure to update the PTR records (which are placed in the reverse domain). Go to the property sheet for your server and set your ISP's DNS server in the "forward to" field.
Your clients must point to your server for DNS. Your server forwards requests it can't answer to your ISP and returns the results to the client.
This method works here and you should be able to make it work for you.
DNS configuration for single server LAN
Do you have the DNS entry for the server's NIC set to the DSL router or to itself. It needs to point to itseld as it is a DNS server.
Try this quick test. Open the DNS MMC from another Windows 2000 client on your LAN. Connect to the Server (in the DNS MMC). Rt click the server name then go to properties. Select the Monitoring tab. Run both tests. This should not be done while on the server as it can return eroniuos results. Did they pass?
If you have your DNS set at root authority it will not be able to hit the internet. The following is straight from MS Study materials:
"To allow your DNS server to perform name lookups on the Internet, ensure that you have not configured a root zone on the server, and that the ROOT HINTS tab in the PROPERTIES dialog box of the server contains a list of servers that are authoritive for the root zone of the internet"
Please feel free to email me screen shots of every properties entry under that zone.
I would suggest deleting and recreating the zone.
Good Hunting!
DNS configuration for single server LAN
The Win2K Server itself is able to browse the internet because it has a DSL router, which is performing NAT, assigned as both a gateway and a DNS server.
I have no proxy server. I expect to install Exchange 2000 on the same machine that is running Windows 2000 Server soon. Eventually, I might host a web site on my server, butright now my web site is hosted by my ISP, which also hosts the authoratative name servers associated with my registered domain name.
I don't mind if the local DNS server gets confused when clients on the LAN try to hit portions of my registered namespace that lie outside my firewall, so long as the clients can get names resolved for the rest of the internet.
Ideally, I would like the DNS to recognize its start of authority at lan.registeredname.com, but by default it sees its start of authority at the root level. If it would just take responsibility for addresses on the LAN and pass everything else to the DSL/Ethernet router, which in turn queries my ISP's DNS servers, it seems like everything should work fine.
The other issue Iam unsure of is how to set up replication given that I only have one DNS server and it really doesn't control anything other than the LAN.
So to boil it down, my questions are:
1. How can I set up my DNS so that it will server Windows 2000 andWindows 9x clients on my LAN?
2. How should I configure replication so that my solo DNS server gets the information it needs but does not become a problem on the internet?
This conversation is currently closed to new comments. | http://www.techrepublic.com/forums/discussions/dns-configuration-for-single-server-lan/ | CC-MAIN-2017-09 | refinedweb | 1,017 | 69.01 |
Recently I was having a look at the online job and internship situation online. Though I started with React, soon Vue.js became my preferred frontend framework. So, when I discovered that most of the online jobs and internships look for React developer, rather than Vue.js developer, I found myself re-learning react from the ground up. Today, in this post I'm going to talk about the points I noticed as a vue.js developer learning react.
Note: All the comparisons are done here based on the "base code" provided by their individual CLIs. So, the simple component structure by importing scripts is not discussed.
0. The CLI:
Both React and Vue.js provide a CLI to set up the projects in an optimal way. In vue.js the CLI takes care of some extra setups like Typescript selection, CSS pre-processor selection, Vuex(state management) setup, Vue Router setup and all that. For doing all those setup in react you need to do it manually separately.
One more advantage of vue CLI over React is that vue CLI also provides a GUI to setup projects.
While the vue CLI being really big it is recommended to install it instead of using it with npx, you can use react CLI with npx directly.
For vue.js you need to install the CLI with this command:
npm i -g @vue/cli
Warning: The old vue CLI is known as
vue-cli. So, if you have that uninstall that and install this new CLI.
Once installed you can use this CLI to create a new Vue.js application:
vue create new-project
However, if you don't want to go through all this slow setup process you can use vite to create vue app in no time, but it is not for production-level apps yet.
npm init vite-app test
On the other hand, to set up a react project with CLI you can use this command:
npx create-react-app test
Or, you can first install this CLI globally and then use it:
npm install -g create-react-app create-react-app test
Did you know? you can use vite for creating react apps quickly as well? Well the command for that will be:
npm init vite-app react-app --template react
1. The component structure:
In vue.js we generally work with components with
.vue extension. These files have three parts:
a. The HTML layout in
<template></template> part.
b. The CSS part in
<style></style> tags.
c. The logical JavaScript part in
<script></script> tags.
Example Vue component:
<template> <h1>Hello World</h1> </template> <script> export default { name: "HelloWorld", props: {}, data() { return { //if any data is required then it is passed here } }, methods: { //all the required methods go here... } } </script> <style scoped> h1 { text-align: "center" } </style>
While in react we work with components delivered by plain Javascript files, sometimes
.jsx files. According to the modern react function based component structure, you will need a function returning HTML like markup(JSX) from a JS function. A typical react function based component looks like:
import react from 'react'; function HelloWorld(props){ //all the component based state/varibales/data and methods can go here return( <h1>Hello World</h1> ) } export default HelloWorld;
2. The HTML/Markup
For any webpage, the most important thing is the markup. In Vue.js you can write your component's markup directly in normal HTML inside the
<template></template> tags.
But in React as your component is returned by a JavaScript function via jsx, so there are some small changes:
a. You can't use
class and similar reserved words in JavaScipt. So you will need to use some alternatives provided in jsx like
className instead of
class
b. pretty much all the HTML element properties are to be written in "camelCase"
3. Dealing with style
In vue.js the style can be defined directly inside the component. It can be written in normal CSS syntax easily the
<style></style> tags. From here you can easily change the language used for styling(SCSS, LESS etc., if it is configured) or you can simply change the scope of the stylesheet.
In React.js there are two ways to define styles:
a. You can write a CSS in a separate
.css file and can easily import it in your react component like so:
import "./app.css"
However, this styling is globally applied.
b. You can write CSS as a JavaScript object using JSS
import React from "react"; import injectSheet from "react-jss"; const styles = { center: { textAlign: "center" } }; const HelloWorld = ({ classes }) => ( <h1 className={classes.center}> Hello World </h1> ); const StyledWorld = injectSheet(styles)(HelloWorld); export default StyledWorld
I avoided the inline CSS part as I don't prefer it as a good method to write CSS
4. Dynamic Variables:
In vue.js the data is normally managed using the data() method where we define a function which returns all of our required data. Then using the
methods we define the functions we can call later to modify the values of the defined data.
But in react you need to use hooks to define both the required data as well as the main method which need to be called to change that data.
To render the value of these dynamic variables directly in the website in Vue we use the
{{variable name}} template literal:
<template> <h1> {{requiredVariable}} </h1> </template> <script> export default{ data(){ return( requiredVariable: "Hello" ) }, methods: { //... } } </script>
While in React we can do the same by using
{variable_name} template literal:
import React, {useState} from 'react' function Home() { const [requiredVariable, setRequiredVariable] = useState("Hello"); //any function which might dynamically update the link by calling setRequiredVariable inside it return ( <h1> {requiredVariable} </h1> ); } export default Home;
4-a Getting and Passing props to elements
In both vue.js and react the props are generally passed directly to the element. Example (with an element named ChildComponent):
<ChildComponent message="Hello" />
Now you can also pass any dynamic data from the parent to the child component. For vue.js, that can be easily done by using the
v-bind or
: directive. Example:
<ChildComponent :
Note: Here a data needs to be predefined with the variable name count so that you can bind it.
If you want to do the same thing with react it would look like:
<ChildComponent count={count}/>
Note: Similar to the vue.js disclaimer, you need a count variable predefined in your component to be used here
Now, how to receive the props? For that, in vue.js in the export part of the
<script> we need to define the props key with an object with details of the props received by that element, with the prop type and the prop name. That will look somewhat like this for a component receiving "message" as a prop:
export default { name: "ChildComponent", props: { count: Number }, data() { return { //other data for this component }; }, methods: { //methods for this component } }; </script>
In react the same thing will be received in a functional component like this:
import React from "react"; export default function ChildComponent(props) { //this is extracting all the props from the general prop object passed. Here I have used object restructuring for that. This can also be done in the function arguments. const { message } = props; return( <div> <h1>{props.message}</h1> {/* The same thing done with the pre extracted variable */} <h1>{message}</h1> </div> ) }
Note: If you are using react route then you get extra information in the props. While using vue.js router you get similar router related information in the special
$route.paramsvariable. This is important info for doing routing in vue.js and react
5 Using Dynamic Variable for HTML Element properties:
If you want to set HTML element properties like href value of a link or src value of an image element (i.e where you need only one-way data binding, as they can't be directly changed in the frontend) you can use
v-bind or its shorthand
: to bind their values to the dynamic data we have in the element. Example:
<template> <div> <a v-bind:Dynamic link by v-bind</a> <a :Dynamic link by :</a> </div> </template> <script> export default { name: 'App', data() { return { // other data linkDynamicallySet: "" } }, methods: { //required methods } } </script>
If you want to do the same in the react, you can directly use the template syntax. Example:
import React, {useState, useEffect} from 'react' function Home() { const [linkDynamicallySet, setLinkDynamicallySet] = useState(""); //any function which might dynamically update the link by calling setLinkDynamicallySet inside it return ( <a href={linkDynamicallySet}>Dynamic link</a> ); } export default Home;
6. Calling the DOM events like "onclick":
React is different from vue.js in the aspect of calling DOM events like "onclick" and others. While in react you can call any DOM events using their "camelCased" version, in vue.js you can call these events using the
v-on directive or the shorthand of that i.e
@ to call the methods defined in script on DOM events.
In vue calling an onclick event on a button looks like:
<button @click me</button>
In react calling onclick event on a button looks like:
<button onClick={updateNum}>click me</button>
Here I have presumed all the other functions are defined properly and accordingly
Did you know? In vue.js
v-ondirective you can call .prevent to execute the
e.preventDefaultwithout dealing with the event object directly in your method
7. Handling form input:
In vue.js you can use the already available
v:model for a direct both way binding to update your predefined "data" easily.
While in react, due to the absence of such directive you need to define how to update your state according to the change of your input field and set the value of the input field according to the state variable.
A simple Vue based form will look like:
<template> <form v-on: <input type="email" v- <input type="submit" value="Subscribe" /> </form> </template> <script> export default{ data(){ return( email: "" ) }, methods: { sub(){ //all the required subtask } } } </script>
Same code in react will look like:
import React, { useState } from "react"; export default function App() { const [email, setEmail] = useState(""); const sub = (e) => { //all required task } return ( <div> <form onSubmit={(e) => sub(e)}> <input type="email" value={email} onChange={(e) => setEmail(e.target.value)} /> <input type="submit" value="Subscribe" /> </form> </div> ); }
Conclusion
Well, this is just the tip of the iceberg. There are a lot of things which I left untouched, most notable among them is state management. I have my very first blog post discussing redux vs context API. I would like to do a similar post about vuex and redux in a separate post. Until then stay home, and keep coding😉.
Posted on by:
Ayushman Bilas Thakur
Web development is my ❤. I love writing blog posts and experimenting with new things!
Discussion | https://practicaldev-herokuapp-com.global.ssl.fastly.net/ayushmanbthakur/react-for-vue-js-user-my-experience-3a2n | CC-MAIN-2020-40 | refinedweb | 1,801 | 61.87 |
MIB Smithy SDK version 3.0 and later include an optional package that provides interfaces emulating those of the widely used (but no longer actively maintained) Scotty/TNM package. The intent of this package is to aid migration from Scotty/TNM by allowing the SDK to be a drop-in replacement for most applications while allowing the use of the SDK's own APIs in parallel.
To enable the Scotty/TNM interfaces, you will need to edit the pkgIndex.tcl file in the lib/smithysdk directory and uncomment the appropriate line to make the package visible to Tcl. If you are currently using the 3.0 alpha version of Scotty, you will want to uncomment the line for Tnm version 3.0:
package ifneeded Tnm 3.0 [list source [file join $dir tnm3.0.tcl]]
Otherwise, you will want to uncomment the line providing version 2.0:
package ifneeded Tnm 2.0 [list source [file join $dir tnm2.0.tcl]]
The main difference between these two packages is that the 3.0 version places the "mib" and "snmp" commands in the Tnm namespace, whereas Scotty provided them in the global namespace in earlier versions. The interfaces provided by MIB Smithy SDK should otherwise support the interfaces of both versions, despite some incompatible changes made between Scotty versions.
The following features are not currently supported or have known caveats at this time:
The following sections may be helpful in migrating your scripts from Scotty to use MIB Smithy SDK's native APIs, which are generally faster and more flexible. | http://www.muonics.com/Docs/MIBSmithy/DevGuide/tnm.php | CC-MAIN-2014-52 | refinedweb | 258 | 56.35 |
Introduction
This clock uses the classic video game Pong to tell the time. The 2 players automatically win and lose so their scores show the hours and minutes. It’s not too hard to build and should cost less than £60 / $100. All the parts are easily available on eBay and the software code is free!
The clock has lots of different display modes to choose from:
- Pong Clock
- Large Digits
- Time written in words, e.g. “Ten Past Twelve”
- Time and date with seconds
- Time and date with seconds and a slide effect
- Time and date with seconds and a jumbled character effect
- Date display with printed retro flashing cursor effect
- 12/24 hour option
- Brightness option
- Random clock mode option (changes the display mode every few hours)
- Daylight saving option to add an extra hour
- Push button driven menus for setup & display selection.
The project uses 2 bright LED matrix panels from Sure Electronics. You can choose between green or red panels with 3mm or 5mm LED’s . An Arduino runs the main code and a DS1307 clock chip keeps time, even when the power is off.
Parts List
- 2 x Sure Electronics 2416 LED Matrix panels (24×16 pixels) in Red or Green (Make sure you get the version based on the HT1632C chip and not the HT1632 – more detail below).
- 1 x Arduino Duemilanove / Uno with ATmega 328 CPU
- 1 x DS1307 real time clock chip and IC socket
- 1 x Crystal oscillator for the DS1307
- 1 x 3.3v coin cell battery and battery holder for the DS1307
- 1 x Arduino prototyping shield
- 1 x Breadboard and jumper wire for testing or if you don’t want to solder (optional)
- 1 x 16 Pin IDC Socket for the display connection
- 2 x Push to make buttons
- 1 x USB Lead
- 1 x Mains to USB power adapter
Plus wire, solder, tools, time, sweat, tears, etc.
Parts in Detail
2 x Sure 2416 LED Matrix You can get these from eBay for around $20 each. They do a red or green display, and with 3mm or 5mm LEDs. My clock in the video is made with the 3mm green displays. Make sure you get the newer version of the display which is based on the Holtek HT1632C chip. You can tell the newer displays as they have the controller chip and DIP switches on the back. The front is relatively empty of components as you can see: clock chip. places like Adafruit, Sparkfun Electronics, Cool Components, Seeed Studio or eBay.
Arduino ‘Diecimila’ with ATmega 328 CPU.
1 x Arduino Prototyping Shield and Header pins. The prototyping board or ‘shield’ plugs on the top of the Arduino making it easy to add other components. It brings the Arduino’s input and output pins onto a circuit board that you can solder things to. Get a board which is designed for a chip to go on, i.e. one that brings each pin of the chip out to a solder pad you can connect wires to. (You can see this area on the bottom left of the board in the picture below.)
Again places like Sparkfun or eBay are good sources for them. You should be able to pick one up for $15 – $20. Check you get the black header pins too as some boards are sold without them. These are the pins that you solder to the edges of the board so it will plug into the rows of sockets on the Arduino.
If you don’t like the idea of soldering, you could get a breadboard and jumper wire to build the circuit on temporarily instead. This is a good idea anyway to test it’s all working. solder it to the shield so we can plug the display ribbon cable in. They are a couple of dollars on eBay. If you aren’t planning to solder, you don’t need this.
2 x ‘Push to Make’ Buttons. These are used to set the time / change the display mode. You can get a pack on eBay for a dollar or two. Any buttons will do, I got these ones that mount on the shield.
1 x.
Circuit diagram
This is how it’s all connected…. not too difficult.
IMPORTANT!
Due to my crappy skils at diagrams the schematic above is a bit off.
- The 2 push buttons are not shown in the above diagram. You will need to connect one button between Arduino digital pin 2 and GND. The other button needs to go between Arduino digital pin 3 and GND.
- The pin layout on the DS1307 is not exact. Pin 8 should really be top right opposite pin 1. All the pin numbers are correct in terms of what they connect to however, so follow the pin numbering and you’ll be fine.
Connecting it up!
LED Displays
The displays use a serial protocol called SPI to receive data. There are only 4 wires needed between the Arduino and the first LED display. Two more wires are required for power.
You’ll notice each display has 2 connectors on the back. These are for daisy chaining multiple units together as we are doing. It’s what the little ribbon cable in the box is for. Connect the displays together using the ribbon cable. You can use either connector on the back – they are wired. If your displays light up the wrong way round, just swap their identities using these switches..
A display with dip switch set as number 1.
Clock Chip
The DS1307 clock chip keeps the time. It uses something called. I’ve had reports of people saying their clock doesn’t tick, only to find out they have omitted the battery, so don’t skip this!
Push Buttons
Connect one push button between Arduino digital input pin 2 and GND, the other between Arduino digital input pin 3 and GND.
Power
We’ll supply power in using the USB port on the Arduino and then connect everything to the Arduino’s 5v and GND pins. Connect the 5v pin from the Arduino to the 5v pins on the display and DS1307. Then connect the GND pin from the Arduino to GND pins on the display and DS1307.
A word of caution with the power: Don’t use a higher voltage supply into the Arduino’s round power jack. The Arduino’s onboard regulator will not be able to cope with the power demand the displays draw. If you try you’ll notice the Arduino will get very hot very quickly and probably not last too long!
Also be very careful if you are powering the clock from your computer’s USB port for testing. You could easily damage the port if you have a connection wrong or if the computer can’t supply enough juice. I powered my setup with my Macbook for testing and all was well, but be warned!
Prototyping shield
The prototyping shield plugs into the Arduino making it easy to add components. On a standard prototyping board you should have room to solder the DS1307 clock, crystal, battery, buttons and the IDC socket for the display ribbon cable. left for the display cable, in the middle is the DS1307 clock chip. The tiny silver capsule below the chip is the crystal. On the right is the coin cell. Below that are the 2 push buttons for setting the mode and time. The red button! Arduino’s site here:
Once the IDE is installed, download the clock code from my page on GitHub by clicking the “Download Zip” button bottom right.
Unzip the clock code zip file. Inside you will see the main clock sketch called pongclock5_1.ino and 4 library folders called ‘Button’, ‘RTClib’, ‘Font’ and ‘ht1632c’. These libraries are extra bits of code needed by the main clock sketch.
Next install the libraries: When you installed the Arduino software it should have created a folder somewhere for your sketches (projects) to go in. Find that folder and see if there is a folder called libraries inside. If there isn’t, create one. Then copy the 4 library folders from the zip file into the libraries folder. After you have done – the file ending in .ino. You should see the main clock code appear in the window. Now pick your Arduino Board Type in the Tools -> Board menu. Then hit the Verify – the check mark icon. This tests the code and should compile without errors. If you do get errors here, you’ve most likely not got the 4 libraries in the right place.
OK, and displays. Then plug the USB lead from the Arduino into the mains to USB adapter.
All being well the display should spring to life. libraries menu
- Make sure you have restarted the Arduino IDE after adding the libraries.
- Check you are using Arduino software version 1.6.5.
I get an error uploading to the Arduino:
- Check your board type and serial settings are correct in the Tools menu.
- Check your Arduino has 32K RAM or more.
The clock doesn’t change:
- Often a wiring issue. Check the LED on Pin 13 of the Arduino flashes. If not then the clock chip is not being read. Check your connections to the DS1307.
- Connect the clock to a computer running the Arduino IDE. Click the serial console button and set it to 57600 baud. You should see the time being printed to the console if the clock is being read. Check the wiring as above if it’s not.
- You must have the coin cell battery connected for the clock to work.
The displays don’t light up
- Check your wiring to the ribbon cables and check the display is getting enough power.
- Try another power supply.
- Remove one display and see if you get half the screen. If you do, then most likely not enough power is being supplied.
The 2 displays show the same half of the clock or the displays are the wrong way around.
- Check the DIP switch settings on the displays are as per the instructions – one set to CS1 and the other CS2. If the displays are the wrong way around, change the display set to CS2 to CS1 and the other from CS1 to CS2.
The text display is garbled after upgrading to 5.1
- Make sure you have replaced the font.h library file with the new one in the 5.1 download.
If you have the older Sure LED Displays
The older LED displays from Sure use a different type of LED driver chip called the Holtek HT1632. You can tell these displays as they have the chips on the front of the LED board. If you have these, you need to replace the ht1632c.h library file in the normal clock code download with this file. Quit and relaunch the Arduino IDE to pick up the new file, then load up the main pong clock .ino sketch file. Next look for this line near the top of the code:
#include <ht1632c.h>
and change it to…
#include <ht1632.h>
Then verify and upload the code as per the instructions above.
French version of Pong Clock with Space Invaders, Sleep Mode & more!
Thanks to Matock who has taken my original pong code and done some more awesome stuff with it, including extra modes like space invaders and a sleep timer. He’s also translated the text to French. If you want an English version you’ll need to ask him nicely in the comments to change bits back! See below for the full list of his changes and a download link:
*…)
Matock’s version is called 5.1FR. Here is his download link.
Thanks…
Thanks to everyone who contributed, including WestFW on the Arduino forum for providing the initial LED driver code, SuperTech-IT over at Instructibles, Alexandre Suter for help with the conversion to Arduino 1.0, Richard Shipman for the lower case font, Matock for the updates & Kirby Heintzelman for all the testing!
Hello, I came across your code for the Sure 2416 LED matrix. Could you send the font.h file?
Amazing work man! Thanks for sharing everything! I guess I will build my own!
Thanks, if you make one let me know!
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Hey, seemed to have taken away the .zip file and just uploaded the .pde. So i can’t find the font file
Hey, sorry about that – now replaced with the .zip.
Nice job. As for the enclosure, you can use a simple pair of plexiglass plates, as I do in Wise Clock 2 (video here:)
Hey Florin, your clocks look great.Did you cut your plastic enclosures yourself? I was thinking of trying some semi opaque plexiglass so you just see the diffused LEDs.
Nice work! I love the clock. Time to upgrade to DS3231! Set it and forget it.
J
Hey that’s cool. Saves the external crystal.
very cool, I may have to build one! Thanks for the detailed build notes.
Looked at it for approx. 30 secs, and decided I _MUST_ build one myself.
Just Ebay’ed the sure-elec led panels.
Happy days!
Hi
Just a quick question but why the 1632c chip spec and not the 1632? What is the difference please?
Mark
Hi,
The Sure display based on the 1632 suffers from getting very dim when a lot of the LED’s are on, whereas their board based on the 1632C doesn’t have this problem. As far as I know it’s because the 1632 needs additional driver circuitry which Sure didn’t implement. The newer 1632C has it built in.
Nick
Thanks Nick
Do you believe then that your code will work with the 1632 displays but the displays will perhaps exhibit just dimming issues?
Mark
Yes it will work, but you’ll need a different library for the 1632, and have to make a coupe of tweaks to the main code – I can email them to you if you are interested. (I had it working on the older 1632 boards before I upgraded them to the 1632C.)
Nick
Yes please send me the code to play with as I have accidentally ordered the 1632 based units and would like something to play with before I can afford the 1632C versions. I am templed by a couple of 32×16 dual colour units though with the 1632C controller.
I assume that you have my email address.
Mark
Hi !
Very nice job !
How do you control Pong ? From the PC ?
No, it’s all done on the Arduino, no PC needed.
Hi,
I’ve got mine up and running!
Atmega328 on breadboard and rtc on a small pcb that I made years ago
Looks awesome!
Hey great news! Glad it worked for you.
Thanks for this project, took a couple of hours to assemble this afternoon – I used a RTC module on a board from bluesmokelabs.com It also took a little while to work out where to connect the switches, your description in the post doesn’t match the photos, but I guess that’s one of deliberate mistakes to keep us on our toes.
It looks very nice alongside my nixie clocks, and I’ll have to build a case for it next week. Then on to try to program some more modes and maybe an alarm sounder…
Thanks again
Hey great to hear you made one. What confused you about the switches (apart from them missing from the schematic)? Maybe I can make it clearer in the instructions.
Love to see the case you come up with too.
Hi, I guess the confusion is in the connection of the switches.
You say connect them between A2/A3 and +5V. This should have been between A2/A3 and GND instead.
Clock is working great here. Etched a custom PCB for this. (so no arduino board needed)
Like Richard, I also have to workout a case for it. (acrylic probably)
Whoops, sorry if that lead you astray – should have checked before I wrote it all up. I’ve changed that now. Thanks for pointing it out.
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Hi
I was wondering if you heard of anyone getting this running using the 5mm version of the 2416 boards. I have been trying, following your instructions to the letter, and I get no where. I do have the 1632c.
Cheers
Hi Todd, I had a quick look at the data sheet and they look the same. (If you load up the data sheet from sure for the 3mm and 5mm models they are the same doc!).
So I’m not too sure why they aren’t working :(
BTW – You could ask on the Arduino forum if anyone has the same displays – there are a few threads about these displays.
Nick
It works perfectly with 5mm version
Thanks Denis
Good to know.
Thanks Nick
I figured I would ask you first just in case and the Arduino forums were doing their migration.
Thanks again for you time.
As proof of my earlier postings, see my version of the pong clock:
the button pins should be on the digital side not the analog side as per the program instructions
Good spot – now updated. Thanks.
I adapted your pong code to Wise Clock 3:
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Nick, Many thanks for the clock design. After waiting for a couple of weeks for the LEDs to arrive from Hong Kong I now have a red version up and running.
I did spot one thing on the circuit layout diagram which seems to differ from your photographs. The connections to the DS1307 seem to be the wrong way around. Using your numbering I have:
pin 5 to +5V
pin 6 unconnected
pin 7 to Arduino A5
pin 8 to Arduino A4
Many thanks again.
Hey Andy,
Really glad you liked the project and have built one. The red LED’s look great! I wish I had bought the dual colour displays now so I could have a menu option to switch colours.
As for the DS1307. The pinout I have is 5 and 6 to Arduino, 7 is N/C and 8 goes to +5v. Pin 8 is bottom right on my photo.
See the chip pinout here:.
Cheers
Nick
Hi Nick
Agree with the bi-colour LEDs they look great. I might just order one of those from sure and knock another clock together. :-)
I have the same data sheet and that’s how I connected the RTC chip. Perhaps I didn’t explain very well… The diagram that you have showing the connections between components has the pins on the right hand side of the RTC running from bottom to top, when they should go top to bottom (so +5v is opposite pin 1 for the crystal).
Hope that makes more sense.
Cheers
Andy
Ah I get you, diagrams were never my strong point! When I get time I might try and redo it.
Hi Nick,
I’ve made a few updates to the Arduino sketch, and was going to upload it to the google code project (but couldn’t work out how).
Have changed the normal_ clock to animate the digits, so when the time changes the changing digit scrolls down off the screen and the new digit scrolls in from above.
Have also added a couple of Binary clock modes.
If you’re interested then drop me a note and I’ll forward the updated sketch.
Cheers,
Andy
Hey, yes definitely – be great to see the new modes.
Nick
Here you go:
Hey Just had a look at your code. I like the new modes -although I’m not sure I’ll ever be able to figure out the time from the binary display!
Hi !
I just saw you pong clock and I must say that it really looks great… I´m using also the 2416 displays but with the older 1632 chip on it. In earlier post I read that you have offered Mark Pepper to send him the code for the old display version. So I would like to ask you if you please can send me the code for the old 2416 displays…. Thank you very much !!!
Hi, just sent it to you.
Nick
Hey Andy,
I have been running your modified code for a while.
Have you seen the new version that Nick has posted?
Any chance that you will incorporate your ideas into this?
I did find an odd bug, when setting up random mode. Sometimes the binary clock is off by ten hours after setting it that way, I can’t remember the exact sequence of vents right now, but I was able to repeat it several times.
Great work though on your additions!
I love seeing activity. It would be really cool if someone would add a seconds readout to the one mode that has time and date. That area of the panels looks like it has enough space for it, and the blank space looks out of balance somehow.
Cheers,
Kirby
Hi Kirby,
Good to hear that you have enjoyed my updates to the pong clock code. Unfortunately I managed to blow my matrices and dont currently have another set to work with, so I cant do any testing. I’ve got another set on the way from China so will take a look once they arrive.
Cheers,
Andy
Hey Kirby, I saw your post and yeah I see what you mean about the unused part of the display that could have seconds in it. I left them out initially as thought it might be too cluttered. Anyhow, I’ve put them in now. Will give you a shout when the new code is up.
Cheers
Nick
Nick,
That’s cool!
I think think it will look good.
Maybe Andy can add his special animation of the rolling digits to this “theme” too!
Good stuff! This really is a very cool project. Wish I knew more so that I could contribute more.
BTW, I will send you some pics of my proto board that plugs on the back, and if I can get motivated, the box I am putting the whole deal in.
Kirby
Hi Nick !
Thanks you for your mail !! and sorry for the late reply…
Sven
Hi,
I was having problems understanding how you brought power to the display boards. When I connected the +5V and GND pins from the display boards to the (I’m assuming) the GND and 5V pins on the Arduino. But I do so, the power light on the Arduino goes off (I guess the Arduino board was drawing too much power). Any suggestions?
Hey, Yes I connect the +5v from the LED boards to the Arduino’s +5v pin, and GND from the boards to the Arduino’s GND pin. Sounds like you might have a short or maybe your power supply isn’t up to it.
Make sure you use a good mains to USB power adapter and connect it to the USB port, or connect a 5v supply to the +5v and GND pins. Don’t use the round power jack on the Arduino.
Nick
Nick,
After retrieving a mains to USB power supply (+5V) there was still no change. So connecting the +5V and GND pins from the display board to the POWER +5V and GND pins should work? Once the +5V pins are connected, the Arduino (Uno) board’s “ON” light cuts off.
DJ
Yes that should work unless you have a short. Both the LED boards and the arduino need 5 volts, so it’s just a case of connecting them together. Have you got a circuit tester – maybe test to see what happens to the voltage when you connect the LED’s.
Nick
Hi i saw this thing and its awesome, now i want to build one my self, Can i connect 4 display modules to make the hole thing bigger? can i use the same code for that?
I am new with programing, but i want to lern how to do.
Sorry for my English, i am from Sweden.
Best regards Axel
Hey, glad you like it. 4 displays would need quite a bit of changes to the code, but you could get the bigger 5mm LED versions of the displays, I have the 3mm ones which are smaller.
Hi, great idea. Very classic and great for gamers! Im curious about turning your idea into a table. That way my coffee table would display the time and play pong as well. Would there be any changes necessary to make it work as effectively as it already does? Thanks
I guess it depends on what you wanted to do. You would maybe have to design new display boards so they could drive individual LED’s to mount in the table. That could be quite a bit of work.
Nick
Hi there, been struggling for a while to get this running before i realised I’m using the ht1632 boards rather than the 1632c. Could you possibly email me the code for the older boards?
Dave.
Sent. Nick
Cheers for that, got the code compiling fine and got the heartbeat on pin13 but no output to the matrix. I’m using the red ht1632 boards, any configuration tricks for them? had a few other demo’s working and I know my RTC works.
Dave.
Hmm. Heartbeat means the clock is ticking and being read OK.
You should see something on the display if all is OK. I have the green boards so not tried the red. Try uploading some of the demo’s in this thread (see the post from WestFW): That’s where I got my code from.
Nick
Nick,
Okay I figured out that some of the connections on my display board wasn’t set up correctly. I have the boards showing up now. Question, is there a way to actually have 2 players be able to play?
That would take some coding and figuring out how to attach 2 controllers to the analogue inputs, it’s possible with some research. There are probably some tutorials on the Arduino site that might help.
Glad you got it up and running though
Nick,
Do you think there is a way to be able to run the game independent of the clock? I don’t have the necessary parts for the clock. I’m doing research right now also trying to figure out how to possibly use 4 push buttons (2 for each player to move up and to move down).
It’s possible, but you would need to change the code significantly.
Nick
Hi DJ,
I have the exact same problem! can you tell me how did you fix it?
Thanks a million!
How can I program four push buttons two for each paddle for a pong game. One being used to move the bat up and the other bat downward? Any ideas would really help!
You’d need to wire them up to 4 spare input pins, then re work the code so it moves the correct paddle up or down, plus you would need to change the scoring, and either strip out all the other clock stuff or add another ‘Game’ mode. I.e. it’s quite a bit of work!
Ok I understand, now in terms of your project I have been able to get it up and running which is fantastic by the way. The only issue I am having is setting the clock. It keeps saying oo:00?
Hi, wow!, what an amazing clock, superb code. I just built one myself. Built a simple but effective case using a perspex sandwich design similar to dotklok casing. Keep up the good work, I just love arduino.
Hi Nick,
You sent me a copy of the code for the older ht1632 controller. I made the changes to the Arduino PDE pong code as per your instructions and replaced the HT1632 file. After uploading to the Arduino and making sure the board was wired up correctly to the display, we had lift off. (Or not). Nothing displayed.
There seems to be a number of versions of the HT1632 file floating around for the 2416 display on the WWW.
Did you get this code working with the older 2416 Green displays. I know the displays are OK as I tried them with a Amicus18 board on another project. Any additional help would be appreciated.
Thanks
Kevin
Hi Kevin,
Yes I had the older versions of the board initially and that was the code I used. I’ve also sent the email you have to a number of other people who have had success using the older displays.
Hard to say what is wrong with your setup. Do you get the flashing LED on the arduino to show the clock is ticking?
Nick
Nick,
The Led on the Arduino comes on but is not flashing.
Tried another arduino unit and same result.
sorry I forgot to say, it comes on, flashes for a few seconds and then remains on.
Hmm. OK just to make sure – this is the LED that is connected to pin 13 on my Arduino. It should flash on when powered up, then stay off for the “Clock version x.xx” message, then start flashing every second when the clock goes in to pong mode.
With the display not connected it will stay off (just tried it). Really difficult to say without looking at it. You might want to see if the demo code from westFW here (see reply 8) works. You may need to adapt the pin numbers. That’s the basics of the library. If not maybe the displays are wired wrong.
Hi Nick,
Yes we are talking about the LED that is connected to pin 13. It it comes on, flashes for a few seconds and then remains on. The same result is seen even with the display not connected.
In terms of the demo file you refer toy, loaded this up and no problems. Worked are described. So either Windows 7 64bit is having a spooky effect on the compiler or my wiring is going wrong somewhere.
Spent ages on the Arduino.cc forum for these displays, a lot of people have a lot of fun with the older 2416 Green units. A couple of the demos produced a mirror effect, seen this before withe Amicus18 , found a fix for the Amiucus and finally the Arduino.
I shall do a bit more work on it later this week, just started working on Nixie Tubes. Even more fun and some interesting high voltages. Still all good fun.
Will let you know if I have any luck, thanks for your help.
Made my own!
I didn’t use your code tho. But thanks for the inspiration !
Hey looks great with the frame!
Hi Nick !
You helped me some weeks ago already and I am really happy with your clock. I used the more exactly working DS3231 real-time clock, and added a DS18B20 for showing the temperature…. So far so good. My question is hopefully without sounding to impudent :
I have 4 of the old yellow Sure 0832 displays and I would like to use them instead of the two 2416 displays. Is there a chance that you can adapt your code for the 0832 displays ? ? Of course you wouldn´t do this for free !!
Regards
Sven
Sven, if I may: you can also read the temperature from DS3231.
As for the 0832 displays, there is also a mechanical challenge in making a bigger matrix. Would be nice to see how you solve that.
Hi Florin ! Yes I know about the possibilty reading the clock from DS3231. But I am afraid that if it is built in a frame the temperature inside will give wrong values and I am not able to measure anywhere outside…. Why is it a mechanical challenge ? I would like to use 4 0832 instead of 2 2416 displays… so the height/dots is the same but it is more width/dots. Like this one here but with the pong clock :
Regards
You are right about the temperature inaccuracy, especially if it’s inside of an enclosure, the values are skewed.
In the video you pointed to, there is a gap between the 2 0832 displays. That is because the displays have the PCB extended so they can be attached (with screws) to something. You would eventually need to cut those extensions, then somehow “glue” the 2 displays together. Not impossible, but challenging (and requires a bit of careful work).
Hi Florin !
I have already cut the extensions and attached the 4 displays together so that there is no gap :-) My problem is the rewriting of the code that splits the information to each of the 4 displays…. Therfore I need somebody :-)
Regards Sven
It’s nice to hear you managed to get rid of the gap. I would like to see your solution.
From what I imagine, the change in the code consists in talking to 4 different HT1632 chips (each controlling a 0832 display) rather than just one (controlling the 2416 display). You will have one CS line to each of the 0832 displays (whose address also needs to be set, with the switches).
A bit of work, but not “rocket science” as they say :)
Hi Florin !
It´s not that complicated… I had to rasp about 0.8 mm on one side of that v -cut point to get them a little closer. I used my small milling machine for that and it took about 5 minutes. Then I soldered a srew with its head down on that silver mounting holes and connected them with the peaces of v-cut material I broke away before (cut them into to the right lenght,drilling holes, and fixed them with a bolt). All together less than an our of work :-) Comming back to my question :-) and asking you directly : Are you able/willing to rewrite the code for me ?
Regards
Sven
Hey Sven,
Thinking about this there are 3 steps needed to get the code working…
1) Replace the current HT1632C driver library with the HT1632 driver – I have this already so not a problem,
2) As Florin says, we will need to re-write the driver parts of the code to cope with 4 displays. I.e. if the main part of the code is trying to plot a pixel at y=9, then it needs to know to plot it as pixel 1 on the second display. I can try and do this for you – but it may be hard to test without 4 displays to hand.
3)Tweak all the various clock routines so they are adapted to the new screen size as you are effectively adding 16 pixels width. – I don’t think I will be able to do this without having 4 displays, so I may have to leave it for you to play with.
Cheers
Nick
Hi Nick !
Of course I understand that it may be hard to do this without having the displays !!
I did step 1 already and currently using your code with slightly changes on the 2 2416 displays. It sounds great to me that you give it a try to do this !! …and of course I will and have to play with it !
Regards
Sven
Hi Sven,
What version of the display do you have? I need to get the datasheet from Sure, but from a quick look they seem to list the HT1632C versions only. Do you have that version or the older HT1362 version?
Nick
Hi Nick, it´s the OLD version HT1632
Sven
Hi Nick !
If you still look for the datasheet…. here is a link :
Sven
Sven, I will give it a try. Are you in a hurry?
Hi Florin !
NO ! I´m not in a hurry…. :-) Good things take time !
Sven
Sven, looks like Florin is doing the hard work here, so I’ll hang back!
Sven, I uploaded this “draft” version for you:
You will also need to download the font3.h file:
I just compiled the code. I did not have the slightest chance to test it (I don’t even have an 0832 display around, plus it’s a Sunday :). You give it a try and let me/us know.
Even if it works, the digitalWrite() functions will need to be replaced with their “optimized” version.
Hi Florin !
Thanks a lot !! You are more than fast :-) I just downloaded it and will try it this evening.
Unfortunately I can´t try it now because I have to work ;-)
I will let you know the result….
Sven
Hi Florin !
I just have tested the “draft” code and here you can see what happens….
I checked the correct connection again but this is ok so far.
LINK :
Sven
Not bad, for a first, blind, try.
It seems that displays 1 and 2 are accessed correctly.
In function displayScrollingLine, you need to make some changes. I left the second param as 0, but it should have been really “y”, and its value, set at the top of the same function, should be between 0 (top of the screen) and 10 (let’s say).
ht1632_putchar(-x+6, 0, ((crtPos+1 < strlen(msg)) ? msg[crtPos+1] : ' '));
should be
ht1632_putchar(-x+6, y, ((crtPos+1 < strlen(msg)) ? msg[crtPos+1] : ' '));
etc (same for the rest of the line).
I think you got the idea.
Hi Florin !
I changed the code to this here :
void displayScrollingLine()
{
// modify this value to display the text on the desired display row;
int y = 4;
// shift the whole screen 6 times, one column at a time;
for (int x=0; x < 6; x++)
{
ht1632_putchar(-x, 0, msg[crtPos]);
ht1632_putchar(-x+6, y, ((crtPos+1 < strlen(msg)) ? msg[crtPos+1] : ' '));
ht1632_putchar(-x+12, y, ((crtPos+2 < strlen(msg)) ? msg[crtPos+2] : ' '));
ht1632_putchar(-x+18, y, ((crtPos+3 < strlen(msg)) ? msg[crtPos+3] : ' '));
ht1632_putchar(-x+24, y, ((crtPos+4 < strlen(msg)) ? msg[crtPos+4] : ' '));
ht1632_putchar(-x+30, y, ((crtPos+5 < strlen(msg)) ? msg[crtPos+5] : ' '));
ht1632_putchar(-x+36, y, ((crtPos+6 = strlen(msg))
{
crtPos = 0;
}
}
Again a link what it looks like :
I will put the displays back together again… it´s not nice this here :-)
From wednesday till sunday I am not able to test because I do a little trip…
But I will be online if there is any question !!
THANKS !!!
Sven,
It look good to me. In principle, it works.
Now, do the following 2 steps:
1. insert these 2 lines somewhere in the file (close to the top):
#define fWriteA(_pin_, _state_) ( _pin_ < 8 ? (_state_ ? PORTD |= 1 << _pin_ : \
PORTD &= ~(1 << _pin_ )) : (_state_ ? PORTB |= 1 << (_pin_ -8) : PORTB &= ~(1 << (_pin_ -8) )))
2. replace "digitalWrite" everywhere with "fWriteA" (arguments to the function will stay the same).
This should speed things a bit.
Hello! Thanks for posting your project. It was extraordinarily helpful.
I got the clock working and even added a speaker and alarm mode to it-was a lot of fun.
I decided to string four of the displays together for a new project. I thought it would be as easy as changing the max x and max y. I was wrong. When I write to the third or fourth display the first and second go besonkers.(any two displays work perfectly on their own)
Any help would be hugely appreciated. I can post an image if you want to see exactly whats going wrong.
Thanks a lot!
Hey Joel, Glad you liked the project and got something out of it. Yes the code wont’ work as it stands as the driver bits are only written for 2 displays.
Each display needs it’s own Cable Select line, so first off you would need to wire up the other 2 CS lines from the displays (CS3 and 4) to the Arduino, say on pins 6 and 7. Set each diplay to 1, 2, 3 and 4, then change the code that defines the cs pins:
static const byte ht1632_cs[4] = {4,5,6,7};
also at the top you will want to set
#define NUM_DISPLAYS 4
and as you say change the max X and Y
Then, in the ht1632_plot and get_shadowram functions, you would need to tell the code which display (variable d) to write to depending on the pixels you want to plot.
E.g. if you had all the displays in a line, X would go up to 96. So plotting X=49 you would want that to be on display 2 (displays are numbered 0 – 3). So Just add 2 more if statments after the ones for x values 0-23 and 24-47. I.e. if the displays were in a line, add one for x=48-71 where d=2 and 72-96 where d=3. You also need to change the x=x-24 to x=x-48 and x=x-72
respectively.
…and youd need to do the same kind of thing in the function: get_snapshotram
There might be some other bits I've missed but hopefully that will get you started! Also see the post from Florin, as he is kindly helping someone do the same but with 4 x 0832 displays… the principle there is the same.
Nick
Hey Joel
I know it was a long time ago you did this but do you still have the code for the alarm part. Im new to this and im not sure im quite up to writing an alarm part for the code. If you do could you upload it some where for me to grab,
Thanks
Ben
yes I had the CS lines and #displays. I had just missed the _plot and shadow ram functions. It works now. Thanks a lot for your speedy reply.
I had read the exchange between Florin and the 0832 displays. I actually have 4 of the same displays. But mine are the newer ht1632c so I figured the code wouldn’t be applicable.
Hey, great to hear it works. Love to see a pic / vid when you are done.
Hi Florin !
I´m back and I just tested the code with the changes you gave to me.
Here again you can see how it looks …… looks the same or is it just bit speed up ?
Thank you !!
Sven
Sven, please also delete (or comment) the line
delay(3000);
in the loop.
….then it is so fast that you are not able to read it anymore :-)
Now you adjust that delay to suit your needs. Start with 10 (which is milliseconds), then increase until you like it.
O.K. I set it to 500…
So I attempted to string four of the 3208 in series. I modified all of the same code I did while stringing the four 2416’s together.
This time.
#define X_MAX 127
#define Y_MAX 7
and
if (x >= 0 && x =96 && x <=127) {
d = 3;
x = x-96;
}
In all the right places. It works great except for the fact that it wont print the rightmost 8×8 block on every display. I know this is because the 2416 is 24 wide and something is still set to that width per display. I looked at the code by florinC but because it was for the ht1632 I didn't know how to adapt it.
I know this line needs to be fixed. But I am too new to this to know how,
ht1632_sendcmd(d, HT1632_CMD_COMS01); // NMOS Output 24 row x 24 Com mode
Any advice for where to go would be great.
Thanks a lot!
Hey Joel, What chips do your displays have on them?
ht1632C.
Not sure if this helps, but I found this in function ht1632_setup() in my code:
#ifdef _16x24_
ht1632_sendcmd(HT1632_CMD_COMS11); // 16*32, PMOS drivers
#else
// (fc)
ht1632_sendcmd(HT1632_CMD_COMS10); // 32×8, PMOS drivers
#endif
Basically, you send the first command for the 16×24 display and the second for the 0832 display.
I am using the 3208 32×8 not the 0832.
I’m assuming other code in the shadow ram methods will have to be changed as well.
Are you sure it’s the HT1632C? The data sheet I found on ebay doesn’t mention it for the newer displays:
Look at page 12 – 3.3. Command Summary.
Under Common options you will want to set xx in:
ht1632_sendcmd(HT1632_CMD_COMSxx);
to the default listed on the page. This command sets up the HT1632 output pins for the display. For the HT1632 version of the 0832 it’s 10 (as in the data sheet above). See if you can find the data sheet for your particular version on Sure’s site.
Also in the code in all the HT1632 related functions where you see the value of 96, that is essentially
96 x 8 bits = 768 bits (double the number of pixels on the display). I.e. half of the bits are used for actual display data, the other half for the snapshot. You should change this to double the num pixels on the 0832.
See if that helps…
I will try that in the morning, thanks a lot!
Here is a link to the datasheet-
Yes its it 1632C.
Yes I had to change it to 00. I probably could have guessed that :/
Now it plots the leftmost 8×8. However, it is only plotting all the even columns. Any idea how to fix this? I already changed the 96’s to 64’s.
Thanks again for your help.
Hey, Really hard to say to be honest without having a look at your code.
Sounds like you are going in the right direction though. Have you written a function where you can plot values and check where they appear on the display?
Nick
Hi Florin !
May I ask if we continue the project ?
Regards
Sven
Sven, what are your requirements?
I thought we/you rewrite the pong clock code for 4 0832 displays and the code you wrote is just to do the basic tests ?
Regards
Sven
Sven,
In Nick’s version of the code I have (which may not be the latest), I identified a few places with dependencies on the screen dimensions.
Here they are (updated with the values for your 64×16 display):
#define BAT1_X 1
#define BAT2_X 62
//very basic AI…
// For each bat, First just tell the bat to move to the height of the ball when we get to a random location.
//for bat1
// (fc) dependent on screen size;
if (ballpos_x == random(40,62)){// && ballvel_x 0) {
bat2_target_y = ballpos_y;
}
//when the ball is closer to the left bat, run the ball maths to find out where the ball will land
// (fc) also dependent on screen size;
if (ballpos_x == 15 && ballvel_x 0)
Nick may have already modified his code to make use of 2 macros that define MAX_X and MAX_Y.
Again, I did not test this code (don’t have the setup to do it). If you find a few things awkward, try to understand what the above numbers mean and play with them.
Hi Florin !
I´ve tried a little bit and it works with some little problems…. :-)
I have a problem with the clear display function. If I use the pong code that has this definition here
#define cls ht1632_clear
I get the error
void ht1632_clear(byte chipno)
too few arguments to function ‘void ht1632_clear(byte)
I deactivated the #define cls and all cls calls and the I was able to upload the first time – of course the display is not cleared then :-(
Do you have a idea what to do to get the clear display function working ?
I ´ve uploaded a video that shows the clock….
THANK YOU
Good job Sven.
Now, insert this function:
void ht1632_clear()
{
for (int i=1; i<=4; i++)
ht1632_clear(i);
}
and leave the #define cls ht1632_clear in place, together will all calls to cls.
Basically, we re-defined the old ht1632_clear (with no parameters) function.
(As before, I did not test this.)
Hi Florin !
I changed it and now I get another error message:
Pongclock_v2_28_0832_test.cpp: In function ‘void ht1632_setup()’:
Pongclock_v2_28_0832_test:41: error: too many arguments to function ‘void ht1632_clear()’
Pongclock_v2_28_0832_test:303: error: at this point in file
Pongclock_v2_28_0832_test.cpp: In function ‘void ht1632_clear()’:
Pongclock_v2_28_0832_test:564: error: too many arguments to function ‘void ht1632_clear()’
Pongclock_v2_28_0832_test:567: error: at this point in file
void setup is this here :
void ht1632_setup()
{
pinMode(HT1632_CS1, OUTPUT);
pinMode(HT1632_CS2, OUTPUT);
pinMode(HT1632_CS3, OUTPUT);
pinMode(HT1632_CS4, OUTPUT);
digitalWrite(HT1632_CS1, 1);
digitalWrite(HT1632_CS2, 1);
digitalWrite(HT1632_CS3, 1);
digitalWrite(HT1632_CS4, 1);
pinMode(HT1632_WRCLK, OUTPUT);
pinMode(HT1632_DATA, OUTPUT);
for (int j=1; j<5; j++)
{
ht1632_sendcmd(j, HT1632_CMD_SYSDIS); // Disable system
ht1632_sendcmd(j, HT1632_CMD_COMS10); // specific to 0832 display, PMOS drivers;
ht1632_sendcmd(j, HT1632_CMD_MSTMD); // Master Mode
ht1632_sendcmd(j, HT1632_CMD_SYSON); // System on
ht1632_sendcmd(j, HT1632_CMD_LEDON); // LEDs on
ht1632_clear(j);
}
}
void clear is just copy and paste from your post before
I don´t know if its important but the the arduino ide jumps (orange-highlighted) on the #define FADEDELAY 50 – doesn´t make sense to me…
Thsnk you !!
Hi there. Im looking for someone to help me create a custom LED project that would need to be very compact. I have a budget and would like to know if you may be interested.
thanks
does anyone have working code for the pong clock I downloaded the original file and got error codes
Probably means you have something wrong in your setup… e.g. you need to copy the libraries from the download into your setup.
Also make sure you aren’t using an old version of the Arduino IDE.
Nick
Hello, I’ve been busy with some other things and just got back to trying to get the 32*8 ht1632C displays working. I left off having everything working except that it is doubling the X value of all the positions. So turning on all the values will actually light only the even columns and the zeroth column. I’m not sure where to go :/ It’s probably something with the bitshifting. Anyway, im happy to send you the code if you want. As a thanks I’m happy to send you one of the displays as well.
Thanks :).
Hey Joel, Thanks for the kind offer of a display… I would love to but I just don’t have the time at the moment! If I get a chance I’ll let you know.
This is a really awesome project! I am a site manager on Instructables.com. You should consider submitting this as an entry to our Clocks Challenge. We’re giving away an iPad along with other great prizes.
You can check out the contest here:
I would be happy to feature it on our site if you decide to post the instructions there and help get it noticed among our 10 million visitors. Let me know if you have any questions!
Cheers!
Carley
carley@instructables.com
Hey Carley, Wow, sounds cool! I like the Instructables site.
Sadly it looks like your competition is only open to the US and Canada. I’m in London, UK, so looks like I’m excluded.
hey nick,
me and my buddy are making a pop shots basketball game we have a string of 18 leds to keep score, i saw this pong clock so i built one and it works great but for some reason it wont change time i think i messed my ds1307 up but, I was wondering is there any way to add a counter to the program to keep score for our game im pretty sure there is a way my programming sucks though any suggestions
Yeah it could well be the DS1307… check all the connections, if they are dodgy it wont read the time.
I’m not too sure on your game but you could use some bits of my code and reprogram it to make a counter in some way. You would need to brush up on your coding though or get someone who knows a bit about it.
Good luck!
Hi Nick
Really great project indeed!!
I have the same idea as “jarell” about building a score counter
Basically I have a RF keyfob with 2 buttons (A and B) each of them giving points to Team A and Team B.
So far everything works on the Arduino serial monitor but I am not capable of displaying the results on the led matrix.
First :
int scoreTmp =0;
int score;
My code detects the state of the buttons and adds 1 for each time the button is pressed:
if (buttonState1 == HIGH) {
scoreTmp++;
}
Then:
switch (scoreTmp) {
case 1:
score1 = 100;
break;
case 2:
score1= 150;
break;
case 3:
score1 =200 ;
break;
default:
}
In the arduino Serial monitor I would use.
Serial.print(score1);
What should I do if I want to display it on the led matrix?
void demo_chars ()
{
ht1632_putchar(0, 0, ‘score1’, (GREEN));
ht1632_putchar(0, 8, ‘S’, (GREEN));
ht1632_putchar(6, 8, ‘c’, (GREEN));
ht1632_putchar(14, 8, ‘o’, (ORANGE));
ht1632_putchar(20, 8, ‘r’, (RED));
ht1632_putchar(26, 8, ‘e’, (GREEN));
}
Thanks for your help.
Hey Daniel,
Really sorry it’s taken so long to respond. You can use the putchar function in the clock code…
Set a message string like so:
char message[8] = {“SCORE 0”};
Then put it on the screen using…
ht1632_putchar(x, y, message[i]);
Where x and y are the pixel coordinates and i is the letter in the message. E.g.
ht1632_putchar(5, 5, message[0]);
would print an “S” 5 pixels to the right and 5 pixels down.
You can also use the above method with
ht1632_puttinychar for small characters
ht1632_putbigchar for the big numbers (there are no letters defined in the font, just 0-9)
Hope this helps…
Cheers
Nick
Hi, great project. I get ” ‘Button’ does not make a type ” when I compile in Arduino.
What does that mean?
I’m just about ready to build it. Any help would be greatly appreciated
Thanks
Oops sorry, I’m so dumb (and french!) When creating the libraries folder I spelt it wrong
sorry to bother, carry on :)
Hi, me again. Could not wait to build this, did it without the ds1307 chip!!
/Users/ericdugas/Desktop/pongclock.rtfd/Users/ericdugas/Desktop/pongclock.pdf
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It is just a wordpress blog – sign up on the wordpress site.
Hey Nick,
just wanted to thank you for this awesome project, i love it !!
I’d just build one for myself and it looks splendid
just because of you, i bought my 1st arduino board and now i cant get my hands of it :p
thank you for that :)
just a little tini tiny thing… for some reason, the clock freezes sometime and the only fix is to reset the arduino board…. (arduino UNO with SM chip)
since my 1st attempt, ive switched to Richard Shipman s evolution of your sketch, and i havent run into the problem anymore… weird
anyway, a BIG THANK YOU for introdcuing me to arduino through this project, and i really hope you ll carry one improving this project and writing some more exciting projects
cheers ;)
Poto
Hey, really glad you built it and got into Arduino!
Since i really want to give you something back, i made a diagram of all the connection, like the one you have but it s in color (not too much tho…) and i ve included the little changes you talked about (pin number on the DS1307, added 2 buttons). Aswell, in case you are planning on going international, i can translate your instructable in french… tell me if you would fancy that
cheers again
Hey that’s great… thanks so much. What did you make it in?
hey nick,
after few more tests, it appears that, even with Richards sketch(invaders), the clock freezes at a random time aswell…
i m lost, i checked connections and all but cant find why thoses freezes happen…
Have you heard of anybody having this problem or any ideas on how to fix it ?
thx in advance
Hey Poto. If you leave it in pong mode, does the time freeze or the ball too?
If it’s the time, I woud check the wiring to the clock chip – power data etc.
If it’s the whole thing check the wiring to the arduino and make sure you power supply is good, If it wavers it could cause things to lock up.
Nick
Hey Nick,
i just checked all that, powered the board through an UPS to really see if the problem was coming from the power… change location aswell, to double check…
but after some investigations, i suspect the ds1307 to be faulty…
i’ll order some new parts and i ll check again
i ll keep you posted
thx for the support ;)
Poto
the ball and the time freezes, but sometime i get the time back rght after reseting, some other times, i don’t…
must be the ds1307
I know I am no wizard but have you tried putting 4k7 resistor betweene 5v and pin 5 and 6?
Eric
Hey Eric,
no i havent try that….
since i know very little about electronic yet, can you explain me why should i do that and what effect will it have on the board ??
and what pin 5 and 6 are you reffering to ?? the ones on the arduino or the ones on the ds1307 ??
thanks for your help ;)
Hi Poto, the pins I’m referring to are of the clock chip DS1307. I’m not really sure about the resistor but they are in the datasheet diagram.
Some kind of pull-ups for the chip to behave normally?
If you try them, tell me if it helps.
Eric
well, i ve tried, and it doesnt work at all…
right now, it s 45:85 on my clock (when on pong mode), and i cant set it right…
if i change the mode to something else (ex:numbers) the time switches every second 12:62, 45:85; 32:54 …
Plus, if i am the only one with this problem, why those resistors are en issue with my clock and not the others ??
i’ll get back to you guys once i ve received the 10x DS1307 i ve ordered…. out of all of them, 1 must work, right ?? :p
thx for the help anyway
Have you tried this sketch?
Eric
The sketch is pretty much at the bottom of the page.
Make sure to uncomment the line
//RTC.adjust(DateTime(__DATE__, __TIME__));
like so
RTC.adjust(DateTime(__DATE__, __TIME__));
I hope this helps
Well, as i was suspecting, the chip and/or the crystal is faulty. I went to the electrolab, an hackerspace in Paris, and they helped me fix it. new ds1307, new crystal, now it works like a charm ;)
thx for this awesome project, and someone mentioned that they wanted to play real pong on he clock; i love the idea so if i make it happen, you ll be the 1st to know ;)
thx Nick, thx Eric
Hey, glad you got it working in the end!
Nick
would it be possible to use an Arduino Mega instead as i have another project in mind that will require the mega
I don’t know as I’ve not got a Mega. I guess you would have to figure out which pins you could use on the mega (as it obviously has more), and change the code for it.
Hi nick,
i ve been making a homemade PCB for this project and so far everything works fluiently but a need an information that i cant find anywhere…
how to change the pin connection between the arduino and the DS1307+ ??
In your project pin 5 of the DS1307 is connected to A4 and pin 6 is connected to A5, i need to change that, where can i do it ??
i ve checked the sketch, the libraries and all but no luck … can you enlightened me ??
thx in advance ;)
Poto
just found out that it cant be changed ….
Hi, have you tried in setup:
pinMode(x pin, OUTPUT);
pinMode(x pin, OUTPUT);
then in loop:
digitalWrite(x pin, LOW);
digitalWrite(x pin, HIGH);
That is what I did in the RTC code as I needed to use Arduino pin 16 LOW (0v) and pin 17 HIGH (5V)
just a thought! again I might be really off the track here!!
Cheers
Eric
Hey Nick
I’m really keen on building a Pong Clock. I ordered also the parts already. Now I opened the code in the arduino program and added the libraries. Then I verified the code and there was a mistake and because I’m new into this I would like to ask you for some help.
every time I push verify, i get this error:
pongclock_v2_27.cpp:18:57: error: WProgram.h: No such file or directory
In file included from pongclock_v2_27.cpp:20:
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:12:24: error: WConstants.h: No such file or directory
In file included from pongclock_v2_27.cpp:20:
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:51: error: ‘boolean’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:52: error: ‘boolean’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:53: error: ‘boolean’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:57: error: ‘byte’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:58: error: ‘byte’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:59: error: ‘byte’ does not name a type
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:60: error: ‘byte’ has not been declared
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/DS1307/DS1307.h:63: error: ‘byte’ does not name a type
In file included from pongclock_v2_27.cpp:21:
/Users/Flo/Desktop/Arduino.app/Contents/Resources/Java/libraries/Button/Button.h:34: error: ‘LOW’ was not declared in this scope
what did I wrong?
greets
flo
Hey Flo,
Glad you wanted to build the clock!
Looks like the Arduino software has been updated and my code no longer compiles :(
Download the older arduino IDE – version 0023 from the download page, it should work with that one.
I’ll have a look at fixing it with the new IDE.
Cheers
Nick
Hi Nick,
Great project! Would you have any example code to do just the ds1307/time display (no pong) on Sure’s DE-DP13112 32×8 display? I’ll have to build the bigger clock though (a friend saw it and fell in love ;), just have to buy the hardware …
Cheers!
Don
Hi Don,
Glad you like it. I don’t have any code to hand, your best bet would be to adapt the code that’s in the pongclock sketch itself. The display you mention looks to have the same controller chip, so it should work with the driver functions. You would need to obviously change where stuff was drawn on screen to fit the new display’s resolution of 32×8.
If you just wanted a bigger clock, Sure do a bigger version of the 2416 boards that use 5mm LEDs. I know a few people have used those with this sketch.
Cheers
Nick
Hi Nick,
Great project, I followed your instructions to the letter and had no problems. I was wondering if it was possible to incorporate an adjustable setting to turn the display off at night. I have a similar option on my Nixie clock.
Thanks again for one of the best clock projects on the net.
Hey Kevin, glad you like it.
It would be possible to dim the display if you were OK with a bit of coding. In the main clock loop you’d want something a bit like…
If (hours > 11 || hours < 6 )
{
clear_display();
update_display();
sleep(1000);
}
The above is pseudo code – it won't work as I don't have the stuff in front of me to look at, but it's the kind of thing you'd need. You can also dim the display (I use it in the code to fade the display). You could set it at a very low brightness.
Hope that points you in the right direction!
Nick
Nick
Hi,
I have tried to compile your script on arduino versions back to 21 but I keep getting the same errors. Any assistance would be appreciated:
pongclock_v2_27.cpp:1:20: error: Button.h: No such file or directory
pongclock_v2_27.cpp:2:20: error: DS1307.h: No such file or directory
pongclock_v2_27.cpp:3:18: error: Font.h: No such file or directory
pongclock_v2_27.cpp:4:21: error: ht1632c.h: No such file or directory
pongclock_v2_27:49: error: ‘Button’ does not name a type
pongclock_v2_27:50: error: ‘Button’ does not name a type
pongclock_v2_27.cpp: In function ‘void gettime()’:
pongclock_v2_27:112: error: ‘RTC’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_chipselect(byte)’:
pongclock_v2_27:123: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_chipfree(byte)’:
pongclock_v2_27:129: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_writebits(byte, byte)’:
pongclock_v2_27:141: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_sendcmd(byte, byte)’:
pongclock_v2_27:165: error: ‘HT1632_ID_CMD’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_senddata(byte, byte, byte)’:
pongclock_v2_27:184: error: ‘HT1632_ID_WR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_setup()’:
pongclock_v2_27:205: error: ‘HT1632_CMD_SYSON’ was not declared in this scope
pongclock_v2_27:206: error: ‘HT1632_CMD_LEDON’ was not declared in this scope
pongclock_v2_27:207: error: ‘HT1632_CMD_COMS01’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_clear()’:
pongclock_v2_27:345: error: ‘HT1632_ID_WR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_putchar(byte, byte, char)’:
pongclock_v2_27:386: error: ‘myfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_putbigchar(byte, byte, char)’:
pongclock_v2_27:413: error: ‘mybigfont’ was not declared in this scope
pongclock_v2_27:421: error: ‘mybigfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_puttinychar(byte, byte, char)’:
pongclock_v2_27:460: error: ‘mytinyfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void normal_clock()’:
pongclock_v2_27:490: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:494: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void display_date()’:
pongclock_v2_27:577: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:577: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27:656: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:656: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void fade_down()’:
pongclock_v2_27:710: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27:716: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void fade_up()’:
pongclock_v2_27:728: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void button_delay(int)’:
pongclock_v2_27:743: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:743: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void pong()’:
pongclock_v2_27:800: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:804: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void word_clock()’:
pongclock_v2_27:1199: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:1203: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void jumble()’:
pongclock_v2_27:1323: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:1327: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27:1451: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void switch_mode()’:
pongclock_v2_27:1478: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void set_time()’:
pongclock_v2_27:1549: error: ‘RTC’ was not declared in this scope
pongclock_v2_27:1550: error: ‘DS1307_SEC’ was not declared in this scope
pongclock_v2_27:1551: error: ‘DS1307_MIN’ was not declared in this scope
pongclock_v2_27:1552: error: ‘DS1307_HR’ was not declared in this scope
pongclock_v2_27:1553: error: ‘DS1307_DOW’ was not declared in this scope
pongclock_v2_27:1554: error: ‘DS1307_DATE’ was not declared in this scope
pongclock_v2_27:1555: error: ‘DS1307_MTH’ was not declared in this scope
pongclock_v2_27:1556: error: ‘DS1307_YR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘byte set_value(byte, byte, byte, byte)’:
pongclock_v2_27:1593: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:1595: error: ‘buttonB’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘byte set_value_dow(byte)’:
pongclock_v2_27:1634: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27:1635: error: ‘buttonB’ was not declared in this scope
Looks like it can’t find the libraries. Make sure you have put the library folders in the arching libraries folder and restarted the arduino application.
Just in case anyone else is trying to get this working on ubuntu (linux) then the following might save you tearing your hair out over the math compile errors:
Thanks for the code, hopefully have the clock running by the end of the day!
EPIC fail! Can someone have a look at this code sheet for my RTC and see what im doing wrong?
Really sorry for the hassle, but im new to ardiuno and a bit clueless as to whats going wrong!
Hi Nick,
Great project – you have inspired me to make one too :) your clock looks great, I have all the parts needed winging their way to me as well as some perspex to make a stand/case
Hey, great to hear it, love to see a pic of the finished item!
Hi Nick,
I love this clock and have built a few for the family. The last one though seems to start up at random. If i turn off with pong running it doesn’t always start with pong when i turn it on although the time is correct.. Could this be a problem with the RTC?
Have you considered incorporating a atomic clock receiver. I recently attached one to my Nixie Clock, the hardware is fairly simple but i am hopeless with code.
Thank you again for a great project.
Hey Kevin,
Glad you like the clock! That’s an interesting problem you have. It should start with pong (if I remember right!). I don’t think it would be to do with the RTC. Maybe the power supply could be doing something funny… but I would expect to see other issues if that were the case. Maybe try running it from another power source as a test.
Not had a look at the atomic receiver … where do you get those from?
Hi Nick,
I will try a different PSU but to be honest I’m stumped with this one. I get my real time modules from Pete Virica at Last time i looked they were priced from £6.95. There is also some references on the site to how they work. Would be a great addition to the Pong Clock
Hi Nick,
I finally found the problem with my last clock. I’ve now designed a pcb specifically for this project called the GURDuino it has a IDC header for the ribbon cable attachement and can be powered by a voltage regulator or +5v psu. I can now use my Duemilanove just for programming.
Hey Kevin, sounds good – what was the problem.
Great to hear you are making a PCB for it.
Nick
Hi i saw this clock and have order all the stuff so i can build one myself, i was wondering if it is hard to add a thermometer mode to the clock ?
I am new to programing but i want to learn becouse you can make so much fun stuff with the arduino.
Regards Axel
Hey, glad you bought the bits. You could add a temperature sensor, but you would probably need a bit of experience coding it in to work with the clock.
There are lots of guides on the net about reading temperature with an Arduno, I would have a look at what is out there as a first step.
Nick
Hi again Nick,
Just wondering if an Arduino Pro Mini would work as well?
Hey Lucian, the Pro Mini is based on the ATMega 168 which doesn’t have enough RAM for the sketch. You would have to spend time trying to slim down the code.
Hi again Nick,
I went ahead and built the clock with the Pro Mini (the older ones were ATMega 168, the newer ones come in 328 flavor too)
Works great, I made a few adjustments like powering everything from a 7805 voltage regulator and capacitor combo (bottom left of breadboard)
May I ask a question, feel free to tell me to go and learn myself, how would I go about inserting a new mode, that just scrolls a piece of text (one of a choice of 4 say) with the cursor effect you have implemented. I’d like to trigger this every half hour?
Making the casing at the moment, will upload some pics in due course. Many thanks for the work you put in :)
Hey, great to see you got it working.
As for scrolling text, well. If you just have a short message that will fit on the screen you can adapt the display_date() function…
Something like:
void my_message()
{
char message[9]={“Hello” };
//call the flashing cursor effect for one blink at x,y pos 0,0, height 5, width 7, repeats 1
flashing_cursor(0,0,5,7,1);
//print the message
int i = 0;
while(message[i])
{
flashing_cursor(i*6,0,5,7,0);
ht1632_putchar(i*6 , 0, daynames[dow][i]);
i++;
}
}
I havent tested the above (and had a few beers) so it may not work, but you get the idea. you will need to call the my_message() funtion from the main loop. If you want it every 30 mins you would need an if statment e.g.
if (rtc[1] == 30){
my_message();
}
rtc[1] hold the minutes value.
If you want to scroll text bigger than the display, you would need to write a new routine that used ht1632_putchar and updated the positions moving each character a pixel along. The format is
ht1632_putchar(xpos, ypos, character);
Hope this helps!
Nick
Hi, i have now assembly my clock and have one problem, it dosen´t work, when i connect the usb cable to the board the power lamp goes on and one of the display is lit say clock but its missing some dots in the text, when i dissconnect power to the displays the orange lamp on arduino bord flashes every seconds so i beleve the clock function works but not the displays ?
What can i have done wrong?
regards
Hey,
Hmm, sounds like you might have something shorting out or wired wrong. The flashing every second sounds like the clock chip is OK like you say.
Try with just one display – you should get half the display working as normal.
Make sure the displays are set to CS1 and CS2 with the switches.
Nick
now i have fix the problem,it was power problem but now when i try to set the clock it wont save it, it just says 00:00 what did i do wrong?
now when the display works the flashing led is solid :/
If it forgets when you turn the power off, it sounds like the battery is not connected right. check your connections to the DS1307 again.
That could also be why the light doesn’t flash. It needs the clock chip working to flash.
Ok thanks i think its the clock chip thats broken, i shall replace it and see if it works
Now it works, it was the clock chip. Its awesome now :)
Hello !
I can not compile the program: (
Shows such errors:
pongclock_v2_27.cpp:18:57: error: WProgram.h: No such file or directory
In file included from pongclock_v2_27.cpp:20:
D:\arduino\libraries\Wire/DS1307.h:12:24: error: WConstants.h: No such file or directory
In file included from pongclock_v2_27.cpp:20:
D:\arduino\libraries\Wire/DS1307.h:51: error: ‘boolean’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:52: error: ‘boolean’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:53: error: ‘boolean’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:57: error: ‘byte’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:58: error: ‘byte’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:59: error: ‘byte’ does not name a type
D:\arduino\libraries\Wire/DS1307.h:60: error: ‘byte’ has not been declared
D:\arduino\libraries\Wire/DS1307.h:63: error: ‘byte’ does not name a type
In file included from pongclock_v2_27.cpp:21:
D:\arduino\libraries\Wire/Button.h:34: error: ‘LOW’ was not declared in this scope
What version of the Arduino software are you using?
I’m using the link on your site:
Download the IDE from the Arduino Site here: Look under “Previous IDE versions” for 0023:
Arduino 1.0 (release notes), hosted by Google Code
I think you have downloaded version 1.0. You need v0023 underneath.
Nick
I installed the 0023 version. Now there are errors:
pongclock_v2_27.cpp.o: In function `__static_initialization_and_destruction_0′:
d:/pongclock_v2_27.cpp:72: undefined reference to `Button::Button(unsigned char, unsigned char)’
d:/pongclock_v2_27.cpp:73: undefined reference to `Button::Button(unsigned char, unsigned char)’
pongclock_v2_27.cpp.o: In function `set_value_dow(unsigned char)’:
d:/pongclock_v2_27.cpp:1658: undefined reference to `Button::isPressed()’
d:/pongclock_v2_27.cpp:1657: undefined reference to `Button::uniquePress()’
pongclock_v2_27.cpp.o: In function `set_value(unsigned char, unsigned char, unsigned char, unsigned char)’:
d:/pongclock_v2_27.cpp:1618: undefined reference to `Button::isPressed()’
d:/pongclock_v2_27.cpp:1616: undefined reference to `Button::uniquePress()’
pongclock_v2_27.cpp.o: In function `switch_mode()’:
d:/pongclock_v2_27.cpp:1501: undefined reference to `Button::uniquePress()’
pongclock_v2_27.cpp.o: In function `display_date()’:
d:/pongclock_v2_27.cpp:600: undefined reference to `Button::uniquePress()’
d:/pongclock_v2_27.cpp:600: undefined reference to `Button::uniquePress()’
d:/pongclock_v2_27.cpp:679: undefined reference to `Button::uniquePress()’
pongclock_v2_27.cpp.o:d:/pongclock_v2_27.cpp:679: more undefined references to `Button::uniquePress()’ follow
Have you installed the 4 libraries? Do they appear in the menu?
in the tabs open files:
pongclock_v2_27
Button.h
DS1307.h
Font.h
ht1632c.h
Hmm. Sounds like maybe there is something up with your install, or you have accidentally typed something in the code.
I’d be tempted to remove the arduino IDE (1.0 and 0023), then the libraries folder as this can hold libraries for 0023 and 1.0 and can get confused. THen try re downloading the code from google.
Hard to say without looking at it :(
I did it !! :)
Binary sketch size: 18200 bytes (of a 30720 byte maximum)
missing library Button.cpp
Thank you for your help !
Hey good news!
What a great looking project. I have ordered the display’s and wired it up and I can get the left part of the display working on both halves of the display by changing the switches but can’t get the whole display to work. I did see it operate once but the R an L was switched around. I turned it OFF then ON again and since I have just had a one sided display. I am thinking maybe a reset pulse but thought maybe you have saw this before.
Hey, glad you like it – really cool you bought the bits. If the displays only work as left, sounds like one of the CS lines maybe isn’t working.
Check all your connections and make sure there are no loose wires / dry solder joints etc.
You should have one display with only CS1 on and the other with only CS2 on.
If they are the wrong way round, just change the switches round. I.e make the one that had CS1 on have CS2 on, and vice versa.
Cheers
Nick
Problem solved. I was running the project on a dual voltage output supply. I switched the displays and arduino stand-alone board to one supply and it works great. Must have been a difference in supply grounds or the project not resetting correctly.
Glad to hear it!
Nick, this is entirely awesome – and that is not a word I overuse! I have my first Arduino board on order and am planning to make one of these as my first project. I’m tempted to try the 32×16 Bi-colour display from Sure, here:
This is also based on the HT1632C – so should it be relatively doable to adapt the code to the slightly smaller display? Or am I missing something? MTIA :)
Hey Matthew,
Yeah unfortunately it would be quite a lot of work to adapt the code – e.g.
– rewrite the driver code to address 1 display not two, and to write in the correct format for that bi-colour display
– rewrite the clock modes to support the reduced 32 pixel width (the 2 displays I use give 48 pixels)
– redesign the fonts to fit 32 width – i don’t think the big numbers will fit.
– add in any customisations you wanted to make it bi colour.
It’s di-able (apart from word mode which might not fit on 32 pixels) but quite a big re write.
Cheers
Nick
Nick, many thanks for the reply. I haven’t got my arduino board yet, but I downloaded and looked through your code – although I’m new to the hardware side of things, I’m a developer by day. Looks very good, commented and easy to follow – so I think doing it with a different display is doable too! Adapting it is probably a good way to learn some stuff about the Arduino too. In the unlikely event my end result is presentable, I’ll send it back to you ;)
Hey sounds great, you can correct all my dodgy coding! Be cool to see what you come up with.
Hi again Nick,
Loving my clock, it really is a nice looking bit of furnature and a good talking point. I am finding writing useful code for it a massive challenge though. I have gone from being an Arduino noob to building your clock and have missed a load of steps learning wise ;) Any pointers on where to begin with these panels? I’ve found a few threads and posts by westfw which might be helpful but any pointers welcome
Yeah the problem with the panels is you need to be a bit of a brainbox like WestFW. He looked at the schematics from Sure and worked out what needed to be set to get them going. You can have a look as a start and see what codes the driver chip accepts – various modes etc etc.
Then I just ended up playing around to learn – think of an effect you might want to do, and see how far you get!
Also, I am seeing some flickering of unlit LEDs, but only ones under blocks of several LEDs (large characters other modes are fine), my wiring seems good…
Normal?
Hey, looks like you have added to the code to get the numbers animating (nice!), it could be a result of redrawing the display a lot.
I don’t see it on mine, but then I’m not drawing the screen as much, or with big block of pixels so much.
Tricky one. If you look in the arduin forums there is an alternative method to drive the display (a post I think by WestFW) that may be better… I’ve not tried it myself though.
It looks like interference or my shoddy soldering :( I uploaded your sketch and it is still visible (under the Pong paddles for example). Then I fired up your sketch with my Uno on breadboard and it is not visible
Oh well, back to the drawing board!
Been working on dimming the clock (the highest intensity is far too bright for night time :D) with help from the Arduino forums. I’ve got two levels sorted (15 and 0) and been able to switch between them on button presses by cannibalizing code. Still working on getting the dimming function to trigger after a certain time though. Would you have any pointers?
Hi Lucian,
This guy I’ve listed has done some work on creating a dimming function, it automatically dims at midnight. Perhaps you could get some ideas from the code.
Awesome, thank you Kevin. I had a quick look at his code, it uses a pretty different method to what I’ve started doing… As tempting as it would be to copy him I am going to figure out what I need to do on my own! :)
Hi, I saw this project and I wanted to have one! Just ordered the parts in China via american and british ebay, have them delivered to Germany within 4 weeks, and built the thing. Great! Everything works fine, but…
When I looked inside the code, I found at least two recursions, which are a NoGo in embedded programming:
Function normal_clock() calls itself in line 487, function pong() calls itself in line 797.
I have not analyzed further, but maybe you will get a stack-overflow when you press the button continously.
void normal_clock(){ …
if(buttonB.uniquePress()){
…
normal_clock();
return;
}
Do I see this correct? Or is there something special in C for Arduino, which I did not understand?
Hey, glad you bought the bits. I’ve not had a look at the code in a long while but it could well be doing things that aren’t recommended. (I’m still quite new to programming on the Arduino.)
Feel free to amend and glaring errors and let me know. I can post the update on the google code page.
Nick
I finished mine last night, but still needs a bit of work to clean up.
Hey, looks good!
Thanks Nick!
I’m hoping to expand the code to add some different modes and animations. Will share my results with you! :)
Great, be cool to see what else you can add to it!
Looks great, liking the red!
Hi Nick,
Still haven’t finished my clock and it’s been MONTHS lol. Have been adding to the code bit by bit though and have learned a lot. Thank you for the push I needed to get into Arduino :) Here is a short clip of my clock. Maybe I’ll finish it before the RTC battery runs out?!
Here it was gone 1 am so it was in dimmed mode and the RGB back light LEDs are on
Wow, LED tastic! You’ve really gone to town with the backlighting!
Heh bright aren’t they!? It’s only 4 X 3mm RGB LEDs ;)
I fired it up just to test it all without the switches. I thought it might work without them I just wouldn’t be able to set them. I fired it up and got clock v 2.27 and then it went blank. Any ideas on where it went wrong?
Also I don’t have the battery rigged up. I am running it straight to the wall cause I was thinking you didn’t need it if you had a continuous source. I also didn’t use any of the resistors that came with the kit because you didn’t show them in your schematic. I did use the 8 pin chip and have it all plugged into a board just using wires – no solder.
Should be fine without the switches, not sure about without the battery, that could well be the problem as after the startup screen it looks to the clock chip to get the time. Another hint will be if the led on pin 13 of the arduino flashes once a second. If not the clock isn’t ticking.
Not sure about resistors, I don’t know which kit they came with – if it was with the arduino shield they are usually for power LEDs. If that’s the case it shouldn’t make a difference if you use them or not.
Cheers
Nick
Pretty sure the DS1307 requires the 3v from the battery, even if it’s powered – not sure what effect it would have on the code, but you should get it connected up.
i am using this: it’s the complete instructions for the ds1307 that i have. I’ll go ahead and put it all together.
Hi Patrick,
I’ve used the same RTC and it works fine once all the components are connected up. The clock will work without the switches for test purposes.
Awesome! I got it working. I soldered up the chip and got everything wired up. I set the time through the computer so I didn’t really need switches to change anything. I’m buying parts for the cubes now about to start on the led cube 8x8x8. Have y’all seen prices on the all inclusive kit. It’s stupid ridiculous expensive!
Hey cool, glad it’s working!
Nick,
Im new to this arduino stuff..just trying to compile the code and its not properly working. I keep getting a code error saying that the button does not name a type. Im not sure if ive correctly saved the library folders but could you give me step by step instructions on how to do that? because i tried following the ones provided and everytime i reboot arduino it seems as if it hasnt recognized the library folder.
thanks very much,
luke
Hi Luke,
Glad you decided to have a go making the clock. What version of the Arduino software are you using? You need the older version 0023. If you can see the libraries under Sketch -> Import library after you restart the software then they are in the right place.
Cheers
Nick
I got the older one and I got everything connected and its working now. Thanks. But its really glitchy..not really sure why though..could it be the code? or is something off about the displays?
Hey, probably not the code as it works for myself and others. I would check all your connections, especially the 4 data lines to the displays and the power to the displays.
Also make sure you have a powerful enough USB supply. If it can’t provide enough juice, you may get unexpected results like glitches on the display. Maybe test it with just with one display plugged in, that would reduce the power consumption.
Hi Nick,
Neat clock. I have ordered all of the parts. Decided to load an verify the code, but I get tons of errors on my Macbook Pro. Yes, I am using a 1.0.x version of the.
I decided to try it on Win7, on my fusion VM, with 023, and it does verify.
I am curious, are you planning on updating the code for version 1.x.x anytime soon?
I once had to roll back to 1.0.1 fro some other example. It gets real messy, I hate using more than one version, especially since there is no support form the Arduino team for anything other than most current IDE.
I certainly do not have your programming skills.
Has anyone else updated your work that you know of?
Thanks for your efforts!
Hey Kirby, Glad you decided to make the clock. I had a quick look at updating the code a while back but I must admit I didn’t get very far. If someone was willing to go through and update it I’d be happy to add it to my google code page. I know it’s a pain working with different versions of the IDE.
Cheers
Nick
Hi! This is perhaps the best creation in the Arduino. I would like to do the same clocks, but I have only HT1632 matrix. : ((
I’m so confused with libraries and code programs that are here in the comments …
Could you send me an e-mail the necessary libraries and program code for matrix HT1632… Please!
Hey, glad you like the clock. Sorry but I don’t have time to re write it all for the displays you have. Buy the new ones, they aren’t that expensive!
I see no resistors? I’m a grade 12 working on a prject so im not good at this stuff, are the resistors built in to the led matrix, if not where are they?
also what type of wire is used? lke when connecting buttons or clock parts and do
I have to add resistors to that wire?
Hey any kind of wire you get at the hobby store / radioshack will do. Like stuff used in battery powered toys or whatever. You don’t need to add any resistors.
Hey, all the resistors needed are already on the LED boards so you don’t need to add any more.
Hi Nick, long time :)
Would it be possible to use different analog ports and how would I go about that? My A4/5 ports are mangled :(
NVM, I cobbled together a £2.99 ATMega328 kit and it works perfectly :)
2.99? Link? :)
I bought a few of them a while back from an eBay seller called offtherails2000, they have since gone up to £3.99 + P&P but it looks like a better kit. I got an older ATMega328p rather than the newer 328P-PU, different LEDs and one tactile button. This guy is really helpful, we’ve swapped a dozen or so Arduino related emails over the last few months, great guy
Hello Nick!
Great project, i really like to rebuild this!
Can you by chance email or share the code for the old “non-C” Holtek HT1632 ?
I happen to have two of these display lying around and want to use them :)
Thank you for sharing this nice thing!
Regards Markus
Hi Markus, I’ve just uploaded the driver for the older style displays to my google code page. There are a few tweaks you need to do to the code that i’ve put in the description notes.
Cheers
Nick
Exactly how long did it require u to publish “Pong Clock | Nick’s LED Projects”? It offers a good deal of good info. Thanks a lot ,Genesis
An afternoon or two. Not too long!
I finished building today and downloaded the code.
It uploade to the Arduino with no error messages, but nothing is showing on my board.
I left all for code unmodified, but I am only using one board right now. Is that why nothing is showing? My second one is on the way, so if I plug in that will this work?
Or did I do something else wrong? Should something still be showing with one board?
Yes you should see half the clock with just one board. Changing the dip switch will choose which half.
Check the dip switches and check all the connections and that you have everything wired to the correct pins. Also check the clock is ticking, the arduino pin 13 LED should flash once a second.
Also check you have the new version of the display board with the chips on the back.
Hello.
I try to uploas your program in my atmega and in arduino software i have this errors:
pongclock_v2_27.pde:-1: error: ‘Button’ does not name a type
pongclock_v2_27.pde:-1: error: ‘Button’ does not name a type
pongclock_v2_27.cpp: In function ‘void gettime()’:
pongclock_v2_27.pde:-1: error: ‘RTC’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_chipselect(byte)’:
pongclock_v2_27.pde:-1: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_chipfree(byte)’:
pongclock_v2_27.pde:-1: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_writebits(byte, byte)’:
pongclock_v2_27.pde:-1: error: ‘DEBUGPRINT’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_sendcmd(byte, byte)’:
pongclock_v2_27.pde:-1: error: ‘HT1632_ID_CMD’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_senddata(byte, byte, byte)’:
pongclock_v2_27.pde:-1: error: ‘HT1632_ID_WR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_setup()’:
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_SYSON’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_LEDON’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_COMS01’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_clear()’:
pongclock_v2_27.pde:-1: error: ‘HT1632_ID_WR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_putchar(byte, byte, char)’:
pongclock_v2_27.pde:-1: error: ‘myfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_putbigchar(byte, byte, char)’:
pongclock_v2_27.pde:-1: error: ‘mybigfont’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘mybigfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void ht1632_puttinychar(byte, byte, char)’:
pongclock_v2_27.pde:-1: error: ‘mytinyfont’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void normal display_date()’: fade_down()’:
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void fade_up()’:
pongclock_v2_27.pde:-1: error: ‘HT1632_CMD_PWM’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void button_delay p word jumble()’:.cpp: In function ‘void switch_mode()’:
pongclock_v2_27.pde:-1: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘void set_time()’:
pongclock_v2_27.pde:-1: error: ‘RTC’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_SEC’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_MIN’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_HR’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_DOW’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_DATE’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_MTH’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘DS1307_YR’ was not declared in this scope
pongclock_v2_27.cpp: In function ‘byte set_value(byte, byte, byte, byte)’:byte set_value_dow(byte)’:
pongclock_v2_27.pde:-1: error: ‘buttonA’ was not declared in this scope
pongclock_v2_27.pde:-1: error: ‘buttonB’ was not declared in this scope
What shoul i do?
Regards.
Oups!!!
I’m sorry, i used arduino 1.0.1, i downgrade it to 0.23 and now it’s ok.
Hi,
I am trying to compile your code using my macbook but I get the following errors. Can you point me in the right direction? I am using Arduino 0023 as suggested in your instructions:
pongclock_v2_27/Button.cpp.o: In function `Button::pulldown()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:48: multiple definition of `Button::pulldown()’
Button.cpp.o:Button.cpp:48: first defined here
pongclock_v2_27/Button.cpp.o: In function `Button::wasPressed()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:73: multiple definition of `Button::wasPressed()’
Button.cpp.o:Button.cpp:73: first defined here
pongclock_v2_27/Button.cpp.o: In function `Button::stateChanged()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:84: multiple definition of `Button::stateChanged()’
Button.cpp.o:Button.cpp:84: first defined here
pongclock_v2_27/Button.cpp.o: In function `Button::isPressed()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:55: multiple definition of `Button::isPressed()’
Button.cpp.o:Button.cpp:55: first defined here
pongclock_v2_27/Button.cpp.o: In function `Button::uniquePress()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:91: multiple definition of `Button::uniquePress()’
Button.cpp.o:Button.cpp:91: first defined here
pongclock_v2_27/Button.cpp.o: In function `Button::pullup()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/Button.cpp:39: multiple definition of `Button::pullup()’
Button.cpp.o:Button.cpp:39:/DS1307.cpp.o: In function `DS1307::set_sram_byte(unsigned char, int)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:209: multiple definition of `DS1307::set_sram_byte(unsigned char, int)’
DS1307.cpp.o:DS1307.cpp:209: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::set_sram_data(unsigned char*)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:186: multiple definition of `DS1307::set_sram_data(unsigned char*)’
DS1307.cpp.o:DS1307.cpp:186: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::save_rtc()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:42: multiple definition of `DS1307::save_rtc()’
DS1307.cpp.o:DS1307.cpp:42: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::start()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:164: multiple definition of `DS1307::start()’
DS1307.cpp.o:DS1307.cpp:164: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::stop()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:156: multiple definition of `DS1307::stop()’
DS1307.cpp.o:DS1307.cpp:156: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::set(int, int)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:95: multiple definition of `DS1307::set(int, int)’
DS1307.cpp.o:DS1307.cpp:95: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::get_sram_byte(int)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:199: multiple definition of `DS1307::get_sram_byte(int)’
DS1307.cpp.o:DS1307.cpp:199: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::get_sram_data(unsigned char*)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:172: multiple definition of `DS1307::get_sram_data(unsigned char*)’
DS1307.cpp.o:DS1307.cpp:172: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::read_rtc()’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:24: multiple definition of `DS1307::read_rtc()’
DS1307.cpp.o:DS1307.cpp:24: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::get(int, unsigned char)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:64: multiple definition of `DS1307::get(int, unsigned char)’
DS1307.cpp.o:DS1307.cpp:64: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::min_of_day(unsigned char)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:148: multiple definition of `DS1307::min_of_day(unsigned char)’
DS1307.cpp.o:DS1307.cpp:148: first defined here
pongclock_v2_27/DS1307.cpp.o: In function `DS1307::get(int*, unsigned char)’:
/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:55: multiple definition of `DS1307::get(int*, unsigned char)’
DS1307.cpp.o:DS1307.cpp:55::/Users/user/Documents/Arduino/libraries/pongclock_v2_27/DS1307.cpp:209: multiple definition of `RTC’
DS1307.cpp.o:DS1307.cpp:209: first defined here
Hi,
when I try to verify the coe, I receive this error:
‘myfont’ was not declared in this scope.
How can I resolve this?
Thanks, Andrea from Italy
Sounds like you don’t have the libraries in the right place. Make sure they appear in the menu like the instructions say.
any ideas on how I can get your code to run on this screen
Would take a lot of re-coding. Plus it’s not big enough – not enough pixels wide.
Hello everybody.
I made my pong clock, i madea video:
I bought this rtc:
But when i set the year, the clock come back to 2010.
have you got an idea?
Regards
Hey, looks great – love the case! Not sure why your RTC doesn’t set the year, it looks the same chip. Does it remember the time when it’s turned off?
You can always cheat and set the year in the software code!
Hi Nick,
Finally got all my parts, and got the clock running. Had a bit of trounle becuase I followed your illustration for wiring the DS1307, even though I really do know how to count pins on a DIP!
Clock still seems to work, though I did put a new on in to see if the Day and Year setting problem I am having went away. It did not. The clock says it is tuesday, even though it is Saturday! And when I go to try to set the time again, it says Tuesday, and the year is always 2010!
I am perplexed by this. Sometimes the day name is correct when it goes through that cursor mode thing, but mostly it is wrong. I am curious to see what it does later in the week.
Times seems ok, though I really wish there was a twelve hour number mode.
Still really fun, but I would love to know why this anomaly is happening. Interesting to see that another fellow is having the 2010 year problem that I am.
I assume that you are really supposed to see the current day and day name when you are in time setting mode?
Best wishes.
Kirby
Hi.
I get the same problem.
If i set 2013 in the year, the days (monday, tuesday…) displayed are wrong.
So i set 2010 for the year, and the clock work fine.
Hey,
Try setting the day individually, Its not clever enough to work it out from the date if I remember right.
Nick
Hey, not near the clock/code so I can’t check, but i think the clock will load up the time set in the main sketch when it goes onto set mode. It it will always be 2010 or whatever. You can change this in the code.
If I remember right, you need up set the day name too as you go through those set screens, it’s not clever enough yet to figure the day out from the date yet.
Cheers
Nick
Ahhhh, you know, that makes a great deal of sense.
I got it set now, so it is near perfect. I think I was skipping through the day and year, trying to reset the seconds to get it close as possible. I am pretty sure I set every item the last time, and that is making sense with what you have said. The dayname and year does always seem to be as you said now that I think about it. Tuesday 2010!!
The kit work marvelously now, thanks so much for sharing your work with all of us!
I wish I understood the programming better, so that I could help you update it for the newer Arduino IDE versions.
I would also love to add a few modes, I love to see seconds incrementing. Kind of like the Doomsday clock I see at Wiseduino, and Wyolum’s YouTube video.
I am running the version that another user listed here, with the animated digits, and blinking colon. I am too slow witted to use the binary clocks! I can’t add it fast enough.
Now I just need to fab a case.
Thanks again! Really really cool kit!
I’m having two problems which I believe to be related. The button folder will not unzip without errors and then I get errors when I compile about button nor being defined.
The Button folder should not need to be unzipped separately, if you unzip the main file you download then all the libraries will be ready, just drop them into the correct folder as per the instructions.
OK, I used win rar to unzip into the libraries folder but I still get an error message when I compile.
Hmm, what exactly is the error you are getting from winrar? maybe your download is corrupted somehow? Try re downloading it. Then all you should need to do is unzip that single file to see the 4 folders and code file.
Hi Nick,
I absolutely love what you have done/are doing here. I’m a web developer with a good knowledge of C# (always have been into electronics). I stumbled across your project and instantly said “Ive got myself a new hobby!”. I never heard of Arduino until i saw this post. ive been aware of electronic dev kits through college mates but didn’t think they would be capable of doing anything more than powering a buzzer connected to two LEDs. Or i have seen motion sensor robots etc.
ANYWAY:
I’m leaving this post to show my appreciation for what you have done and to say i have ordered all of the components except the RTC. I was looking at this and wondering if it would work and if so which connector is the 5v? I know the Arduino analog pin 4 connects to SDA & the Arduino analog pin 5 connects to SCL.
It will probably be a month or so by the time i get all the parts and all running. Ill hopefully post a video once things are running.
Sorry, after a bit if goggling i found out that the 5v is the VCC. However my question still remains if this will work? i see it has two sides to it with P1 & P2 sets of connections. Also the fact that it comes added with an eeprom, resistors & diodes which i don’t quite understand their presence.
I’m sorry but my expertise isn’t in the hardware department, i just know enough to get me by :).
Hey James. thanks for the post, really glad you’ve been inspired to get into this stuff!
Yes Vcc is the 5v like you say. As for that particular RTC module, I can’t say for certain, but it looks like it should work. There’s no circuit diagram, but I’m guessing the RTC connects to one side of connectors, and the EEprom to the other (not sure which is which). My RTC also came with an EEprom so they are often sold together by the looks of things.
I guess you’re gambling $2 here… so maybe not the end of the world if it doesn’t pan out! Let me know how you get on.
Cheers
Nick
Yea if it doesn’t work attached to the board i can always separate the individual parts.
I wonder if you could help me with another similar project. I have removed a 7×80 color LED matrix from a text scroller. I think there was something wrong with the board attached to it, it was used to show film times above a cinema screen.
My question is: on the matrix it has a set of 10 2pin connectors in a row. It looks like your 16 pin IDC only without the plastic surround and with 20 pins. Is there any way to know or find out which pins are which. Like i said before im not a hardware person. But i would like to connect an Arduino to it and revive it as a text scroller, or maybe another clock. I know this is off topic from your clock but i would greatly appreciate your help as i cant seem to seem to find an answer online.
Thank you,
James
No fraid not. It’s impossible to say unless you can find a wiring diagram or identify the ICs and trace the pins.
Nick
Hey, Nick.
I built the clock, and I’m having trouble getting the clock set.
Once I set the time, the cursor flashes on screen for a few seconds, and then ”
0TH
Y
”
Is displayed and fades after a few seconds.
And advice?…
Thanks.
Hey Alex,
Weird one, does the time change if you leave the clock alone? If not I’d say it’s not reading the time from the clock chip, so check the connections to that.
Nick
Hey, I was able to figure out what the problem was. I wired it up exactly as it’s pictured in the schematic and didn’t read what you have right under the picture. Oops.
Hmmmm….. sounds very familiar!
Did the exact same thing myself a few weeks ago when I built mine!
The RS1307 got pretty hot….. but it still worked after I corrected that problem.
And as I mentioned earlier… I should have known better, I know how to count pins on DIP’s!!
Woo Woo! After a month of waiting on the parts they all finally arrived (With the setback of customs holding and charging me €13 for the LED matrix, Sure Electronics declared them as bottles!). I had all built in a couple of hours and it worked first time, All down to your great instructions. Thanks again Nick! Have you tried powering the clock from a battery pack and if so how long did it last?(would the 9V provided from the battery constitute as too much power as per your warning?)
Hey, great news! Glad you made it! Annoying about the LED panels though.
A 9v battery (rectangle one) Wont give enough power to run all those LEDs. You’d need a chunky battery to run it for any length of time – maybe a bunch of D cells with something to bring the voltage to 5v?
Nick
I’ve read your tutorial…great. You explained this really well. I’m waiting for the LED matrix and i want to put two pot to play pong! I’ll let you know ;)
Congratulation for your work.
Valerio
Hey, hope you have fun making it !
Hello,
Thank you for this project.
I have built one, using the 5mm displays. It seems to be working fine, however I am not getting any clock signal (time stays 00:00) I am using Grove RTC from seeed as I couldn’t get my hand on a DS1307 by itself.
Do you think my problem is because I am using Grove RTC? If yes, can I tweak the code to get it working?
The sample code project on Grove RTC doc seems to function correctly (I can see the correct time on the serial)
Thanks again for the project and for your time.
Glad you built one. That grove RTC should be fine, it just looks like a DS1307 packaged on a circuit board. Just check you have it wired up correctly, the doc I found mentions something about a base shield that plugs into the Arduino. The arduino pin 13 LED should flash once a second when it’s connected right.
Nick
Hello again,
I managed to get it to work, however there are some weird behaviors, here is how i got it to work:
1- I got an actual DS1307 and the behavior was the same as with the grove RTC.
2- The led on Arduino is always on (not flashing), however when i added a 220ohm resistor and a led on pin 13, it started flashing.
3- The set clock function in the code never works, to get it working, I had to set the time first using a code sample i found online for the DS1307, I was able to confirm this because the sample code uses the same pins as the pong clock to communicate with the DS1307 so i am sure it’s not a connection error.
When i set the clock with sample code, pong works perfectly, if i disconnect power and battery, pong shows 00:00 forever, setting the time does not work.
4- Since, the code sample I have does not set the day of the week, the clock thinks it’s always Tuesday and never updates that even when a day passes.
5- All other clock modes(apart form Pong) do not work properly:
5.a- Words mode: always shows Twelve o clock for 1 sec, then the real time for 1 sec and so on.
5.b- Jumble mode: keeps randomizing every second, using debug, the variable mins was not correct, either empty or has the wrong minute, so I changed the for loop to be “rtc[0] == 59” instead of “mins != rtc[1]”, which seems to have fixed the problem, however the day of week was still garbage since it was not set, so i replaced the array with months, it works fine this way, however as soon as you go back to another mode, you find that the time has been stuck in the past and did not update, the only way to get it back to work is to set the time again using sample code.
5.c- Normal mode: Displays the correct time for 1 sec then displays 00:00 forever
5.d- Random mode: Seems to be okay, it’s just that most other modes do not work.
5.e- Pong mode: Works perfect, I left it overnight and the time was right, disconnect/reconnect power and time was still good.
5.f- Set clock: Only saves time, not the date/day.
5.g- Display date: Sometimes shows: ET HOUR 0TH. and sometimes shows the correct date.
Since I do not know very well Arduino nor C++ I cannot tell what/where is it going wrong, but while debugging, I can see that the rtc[] array in pong mode returns the time correctly, while in all other mode there is a parameter or two incorrect.
Have you seen anything like that before?
Thank you again for the project and for your support; And please excuse my very long post.
Achraf
Hey,
This is all very strange, I’ve never seen this behaviour. Everything should just work, you shouldn’t have to start changing odd things in the code per mode. If the time data is correct they should all be fine.
It sounds like you have a bigger issue, maybe an unstable power supply? Does it work without the displays plugged in and some debug lines, or with just one plugged in? Try and reduce the power draw. Are you powering via USB?
Do you another Arduino to test it with?
Nick
As per your advise, I tried to disconnect the second display, it seems to have worked, all modes work better now, except numbers mode, which now blinks the real time and 00:00 every second.
My arduino is powered by USB (from PC when debugging and from a 2A USB adapter when not)
My multimeter reads 470 to 480mA when both displays are connected and 500mA when only one is connected.
I unfortunately have no other Arduino to test with.
Regards,
Achraf
Solved. Simply switching to a DC adapter fixed all the problems! I don’t really understand why, I have to admit, it’s my first arduino project and I am a bit confused by this behavior.
Again, thank you for the great project and for your support.
Achraf
Ah well done. It sounded like it might have been something funny with the power. Really glad it’s working!
Hi, i build thi clock för about a year ago, now i have a problem, the clock hangs up and freeze the display, i have to disconect power to reset it. Why is this comming after a year ? And is there any sollution for it ?
//Axel
(sorry for my bad english)
Hi Axel, try a different power supply. If that goes bad lots of strange things can happen.
Thanks Nick for a fantastic project, I would like to see the 2 Binary modes from 2.28 incorporated into 4.02 !! I have had a play with the code but I’m not clever enough to know what I’m doing !! Anyone like to help me out ?
There’s a guy who has done some work on it on Instructables – he might be able to help. I don’t have time to code it all these days.
Nick
Hi again Nick,
Anxious to load your new update!
12 hour mode is a great addition.
I am currently running the modified version that has the two binary clocks, and animated digits. I hope that programmer will incorporate your changes. ( I did find a repeatable bug in that version hard to explain ).
I have built two clocks now. One green with a shield on a Diavolino, and now a red one with no shield at all. While I was building my own single board proto board, which was getting a bit messy as far as the wires, I found a great product that I wanted to share with everyone.
I am using this “kit” for my second clock, and it is working well.
I have soldered a female 16 pin IDE conector on to the board, and I am plugging the whole board directly on to the LED matrix, eliminating one cable. Connector placement is critical, for the board to fit. If I knew how, I would design a complete board to do all of this. I know I saw some person’s project that did that very thing, but can’t find it now.
This is a bit tricky I must admit. Had to cut a few traces carefully, and remove a few pins on the connector. The nice thing is that it cuts down on the number of jumper wires. There are some power considerations, but I hope others can work that out if they decide to try this neat Arduino clone.
Thanks again for your work and generosity on this clock!
Kirby
Hey that is a great idea having the connector directly on the board with the Arduino, saves a ribbon cable and makes it more compact. Send me a picture when you’re done!
Someone was actually meant to be designing a dedicated PCB for it actually, but I’ve not heard anything back as yet.
Nick
Hi Nick,
Can’t wait to have a dig about your code to see how you achieved dimming. It took me a month of head banging and still isn’t quite bug free! Sometimes my clock bathes my room in glorious green LED light at 3am :p
Hey, the dimming mode was actually added by a chap over at Instructables, so I can’t claim the credit there!
Whadda’ ’bout the12hr mode?
That’s my fave ill’ improvement/feature?
Hate military time!
Cheers!
Hey!!
I recently built a pong clock of my own and wired it up all right (So I think) and it seems to work but I cant set the time!!! Every time I try it always reads 00:00 or 12:00 depending if I have it on a 12 hour or 24 hour time, anyone have any ideas of what is going on?? I thought my RTC chip was broken or something so I used another one but still, the same problem. Its been happening for a few weeks now and I have no clue what to do so can anyone help me????
Are you absolutely sure that you have wired the RTC chip correctly? If the time is not changing at all, something is definitely wrong.
I wired it first time so that it physically matched the drawing, but Nick pointed out clearly in the docs that the pin-outs on the chip in his drawing are not as they really are on the chip!
The numbering goes counter clockwise from the top left most pin when you have the dimple or other pin one marking on the top. So 1 & 8 are opposite each other as are 2 & 7 etc.
I was truly embarrassed, because I know how chips are numbered, but I blindly followed the drawing. Once I realized that, and corrected the wiring, all has been well, and now I have built two! One red, and one green, kinda’ like New Mexico Chiles.
Hey Kirby,
I wanna thank you so much for replying!! Ive been having this problem since the start of the summer and I could not be able to understand why! I know that 1 and 8 are opposite each other and I am 99% positive I wired it up correctly. My chip looks exactly like the on in the photo except for the big circle in the bottom left corner. And I presume the leg next to the circle is leg number 1 which is left of the semi-circle on top and thats exactly how I wired it up. Also since Im kind of new at this I tried wiring it up all different kinds of ways, none of which worked. Do you have to somehow program your RTC before it works?? Any help would be appreciated!!!
-David
I’ve tried everything you’ve said and read other posts as well. but its not working. Could you please do a video tutorial on this. And also a way to test if the led matrix is working.
Sorry what’s the problem?
Nick
Nick
Just wanted to thank you for the clear explanations to build a great project! I love my pong clock and have learnt a lot making it.
Matt
Hey, really glad you made one!
I should have an update to the code out soon(ish) too.
Cheers
Nick
Nick,
Thank you for a great site and tutorial.
I have a weird problem. I was using TIny RTC as a replacement for DS1307 and clock was working fine. Than something happened (no idea what) but time no longer will save nor Arduino can retrieve time from the RTC. I thought since in your specs you specifically said to use DS1307 I ordered that and got it all setup on the breadboard. I can see that if I had wiring or some issues sketch wont work so I know that all my wires are connected correctly and clock is showing up on the display, the issue is same as with Tiny RTC , time wont come (get_time()) and nothing gets stored on DS1307. Clock always show 00:00 and Tuesday Jan 1 2000.
I have also taken out all wiring , kept only the clock circuit and loaded TestRTC sketch. I can set the time and date and retrieve it too. It confirms that I can get time from the chip but the pong clock sketch is unable to retrieve. The amazing thing is that every thing worked for three or four days and than it all stopped.
Regards
Naveed
Oh just to update, I did google on the pin configuration and got it working correctly. One of the way of knowing is that when you have wiring wrong on the chip you only get the pong clock version 4.0 and nothing moves further. Once you fix your wiring on the chip every thing works except time is not correct.
Hey, the tinyRTC module looks to have a 1307, so should be the same as a separate 1307 chip.
Weird it works on the test script. Could it be a power thing? Maybe try another PSU.
Or could you stick the testRTC script as a new function in the pong sketch, and use that for gettime() as a test.
You can also add print statement to the clock code to print rtc[0] (secs) rtc[1] (mins) etc to see if those values change.
Hi Nick, great project.
I am having problems getting the components for this to work!
I have purchased so much from Sure Electronics over the years, amplifiers and all sorts… It seems they no longer sell the displays… “2 x Model 2416 LED Matrix Displays from Sure Electronics.” I do know they used to sell them so its of more frustration!
Do you or anyone know where:
1) I could get the 2416 modules; or
2) Any similar setup that can be achieved from the led matrix modules that are real cheap, with some controller IC or components to achieve something very similar?
I tried ebay, amazon, alibaba/aliexpress and even Googled… but to no avail.
Any help much appreciated! :)
Hey,
Looks like they do still sell them: (84 in stock)
or from ebay via sure-display:
Nick
Hi Nick,
I must have been searching wrong, part of the problem was I searched sure electronics ebay account and overlooked I was searching the wrong one!! Sure display!! of course…
A shame I couldn’t get the 5mm green one, but on second thoughts the smaller leds would probably work better. I spent a while thinking Red or Green… decided to move away from Red like the segment alarm clocks.. so green will look a little more ‘cool’.
So I have ordered the parts now. I read £60, thought… £85, but actually its almost bang on to £60 – so the estimate is spot on.
Looking forward for it to arrive so I can tamper about with the code a little and see if I can modify it. I will post a youtube video or something of the end result.
Hey,
Yes looks like they have changed their ebay account name, or added a new one at least. I’ve got the smaller green ones and they look good.
Be great to see what you do with the project and code.
Another report of a successful clock build. I used the Tiny RTC which are available on ebay. The Tiny RTC contains a DS1307 chip. The pin-out is as follows
SCL=Pin 6=Arduino A5
SDA=Pin 5=Arduino A4
VCC=5V
GND-GND
The Tiny RTC also contains a temperature sensor which I would like to add temperature to the Pong Clock. Has anyone done this?
It would also be nice to set the time with the atomic clock radio signal or using a GPS receiver
Hey great news Jim. Post a pic if you can!
Temperature would be a good addition. You might be able to use some raw I2C commands to grab the temperature direct from the board without having to ditch the RTClib library I use. Maybe ask in the Arduino forums as I couldn’t see anything with a quick google. You’d want to stick the commands in the get_time() function. Then I guess you could tack another screen on the display_date() function to print the temp, or maybe another menu option for it.
Alternatively if you can’t use raw i2c, looking here:
They provide a library to read from a board which looks similar to yours:
#include
So you could adapt the pong code to use that library to get time and temp instead of RTClib – specifically these functions:
get_time() – reads the time from the RTC
set_time() – set the time on the RTC
set_dst() – adjust the daylight saving option by setting the RTC
setup() – you’d need to add whatever is needed for the new library
plus change the ds1307 object at the top of the code.
The new library looks pretty similar to what I used – ie. you create an object and use it to set / read the time – so it shouldn’t be too tricky.
Thanks for sharing this. I made 1 and it works well.
Glad it works!
Can anyone tell me what I need to do to use a DS3231 RTC on this project?
Thanks.
Hi Nick, I see you are looking to get a PCB designed ? I would give it a go, however I feel you would be better to design a PCB shield for the UNO. If you want a complete PCB so you can do away with the Uno, you will need to replicate what Arduino have done so fantasticlly and people would need to have the Atmel with the boot loader already burnt, and you would still need to provide a way of uploading the code. Let me know if you want me to have a crack at it.
Hey Gary,
Thanks for the kind offer of giving this a go. I thought about making a shield to start with, but then I realised a lot of the stuff on the Arduino / Uno isn’t needed for the clock, plus one PCB would be smaller and more compact. Ideally with an IDE socket on it so it connects straight to the display (i.e. no ribbon cable).
The ATmega doesn’t need much at all to support it – just one resisitor, 2 capacitors and a crystal. See:
You can buy pre programmed ATmega chips from Ebay and I was thinking of having a header for an FTDI cable for people to program them with.
Hi Nick,
O.k I will give it a go, I forgot to ask if you still want the Pong clock to be powered by USB cable ?
Give me a few weeks and I should have something ready.
Hey, great you’re having a crack at it!
Good point on the USB. How about we
just go with a 5v ‘wall wart’ and round jack. Might be cheaper.
Been following this blog forever, my pong clock is on perpetual hiatus, but WILL be finished sometime :p I’m using a bare ATMega328p chip instead of an Arduino, soldered on to a small piece of perfboard. For power, I have a bag of these I bought some time ago, cheap as chips and really handy
Has a DC jack and a USB port, not to mention power switch
I was also thinking of keeping it a single sided PCB, cheaper and easier to be made at home, but has some limitations i.e may need jumper wires, I will have a play around and see what works best.
I was also going to include a reset switch, or at least a place to put a reset with if required.
Hey, good point on the single sided idea. I’ve never made a PCB so didn’t consider that idea. A reset switch would be good, maybe even a spot for the led on pin 13 that flashes seconds.
Hi Nick,
It’s been a while since I left you a comment here. Great to see so many pong clocks being built!
I managed to blow my first set of panels with some dodgy soldering. I kept meaning to get another set sent over from China, but never quite got around to it. Then I found a 16×32 RGB matrix ( ) that was easy to get hold of in the UK ( have them) , and re-wrote your code to work with it.
I added a microphone, and gave it a spectrum analyser mode:
and then added an ethernet shield to go pick up the weather forecast
So, many thanks again for such a great project. It’s kept me busy for many hours. Everybody loves the clock when they see it.
Cheers,
Andy
Hey Andy, that looks awesome, you’ve really gone to town with it! Love the colours. I must admit I have a 32×32 one of those matrices currently languishing in a drawer as part of a half completed project. I was trying to hook it up to a raspberry Pi but I couldn’t get the bit rate fast enough. I should revisit it sometime.
Glad you got inspired though!
Nick
Hi Andy,
That’s a very cool mod you have going there!
Do you by any chance plan on sharing the code and wiring with the world?
Just curious. Always looking for another LED project.
I am really enjoying Nick’s latest version, with the seconds, and rolling digits, not to mention 12 hr mode!
Cheers!
Kirby
Hi Kirby, I’ve put the code up on github. Haven’t done a wiring diagram yet, but that’s the simple part :-) Plus, Adafruit have a load a great tutorials on wiring all their kit up.
Hope the code is of interest.
Cheers,
Andy
Hey Andy,
Thanks for sharing your code.
I have been taking a look at it, and I cannot get it to compile without a long list of errors. Some of it I know is the lack of certain libraries on my machine. Having a hard time tracking them all down.
Also, just wondering if this was written to compile with IDE 1.x, or if it needs the older IDE, as Nick’s old version did.
I had the idea of possibly trying to get it all to run with the Nootropics piggyback board for the Matrix, modified slightly with an added RTC of course (pins 4&5 are unused on that board), and with the Ethernet, audio etc. stripped out, sort of like an RGB version of Nicks version of the clock.
It is probably beyond my skill set, but I was poking around wondering what it might take.
Best wishes,
Kirby
Hi Kirby – Apologies for not including all of the library references. I believe that these are the non-standard ones:
AdafruitGFX
RGBmatrixPanel
DS1307RTC
ffft
I’m using Arduino 1.0.3
I’d not heard of the Nootropic board before – looks excellent. I guess the only thing you might struggle with is memory – the additional libraries add a fair amount to the compile size, but you might be lucky. Andy, I would appreciate your help. I ended up with the same RGB display like the one you’re using. This fact, lead me in trouble, as Nick is using a monochrome version.
I don’t have the ability to change the code, or re-wire the timer.
I am trying to use an Uno, but also have a MEGA2560, if more convenient.
So far, I have managed to hook up panel with UNO, and run a demo code, following Sparkfun’s tutorial.
Now, I ‘m stuck, trying to follow Nick’s instructions. There is a conflict in wiring setup. The ds 1307 push switches are supposed to be connected to dig2 and 3 pins on uno, but these pins are already hooked up on the display.
Probably you already have worked your way around this problem.
You ‘re mentioning this is the easy part..! on another post.
Please bare with my ignorance :-\
I really want to finish this project (my first one actually).
Any advice/help regarding code, setup will be more than appreciated.
Peter
Peter
I’ve used an UNO and 2560, no problem… just watch the wiring…
Re the pushbuttons, they go to Digital 2&3, the Display goes to 4,5,10 & 11…
No conflict!?
Hope that helps
Anthony, thank you very much for your reply.
Maybe, I wasn’t very clear, excuse me.
I have the 16×32 RGB version display.
please check×16-32×32-rgb-led-matrix/connecting-with-jumper-wires
or
these are the tutorials I followed, to test the display, and it works.
I run into problems, when I try to follow Nick’s instructions.
Andy has worked this out (with RGB) but unfortunately no wiring guide is provided.
Maybe this is easy, but I am tragically fresh in mcontrollers, I need help.
Any advice welcomed.
Peter
Hi Pete,
I put my RGB version of Nick’s code here:
I think you’ll probably need to go with the MEGA as the UNO will be short on memory.
Wiring info can be found here (you’re not the first to ask).
An alternative to using Arduino is to use a Particle Photon. Someone else has taken the RGB code, and got it working on the Photon, and they’ve even created an add-on board that plugs directly into the panel. More details can be found here:
The photon has built in wifi, and can handle the weather display thats part of the code without the need for a proxy to translate the weather feed from weather underground to a simple format.
Good luck!
Andy
I forgot how cool the rgb version was! Nick,
Saw your project and just HAD to do it.
Got all the parts and downloaded the most recent code to run with the Arduino 1.05 software.
Loaded the four libraries and when I went to compile I get the following error:
error: ‘myfont’ was not declared in this scope.
The Font library is in libraries folder as well as the other three libraries and were imported via the Arduino program as I normally do for other libraries on other projects..So I am kind of at a loss to understand what is wrong.
I program my Arduino with a PC and not a MAC but as far as I know that should not be a problem
Any help would be appreciated.
Thanks,
Paul
Hey Paul, that’s strange. Do the libraries all show up in the libraries menu?
Nick
Yes they do. That is what I found strange too.
I have seen a couple other comments posted with the same problem. The reason I mentioned that I was using a PC and not a MAC is that the zip file for the Pongclock5 seems to be set up for a MAC.
Thanks for responding… Paul
Yes I made the zip file on my mac, but I think it should be compatible with PC.
How do you know the zip was set up for mac by the way?
When I unzipped the files to my computer I come up with a directory called __MACOSX as well as the 4 library file directories, Pongclock 5 directory and a Readme.TXT file. The __MACOSX is the dead give away.
Hah, yea that is a bit of a giveaway isn’t it! I forgot how Windows will show the Mac’s hidden files.
Can you confirm you have the include Font.h line at the top of the code under the //include libraries comment? I get the same message if I take that out.
Maybe also check to see that you don’t have another Font library installed that’s conflicting. As a check you could rename your current libraries folder to something like libraries_old and then create a new one just with the pong libraries in.
Hey Nick,
Your trick with creating a library file with just the PongClock5 libs worked like a charm. Have to remember that one in case of similar future problems. Thanks again so much for your help. It is much appreciated. Looking forward to getting this going later today. Still woking on a few “Honey DOs”
Paul
Hey, glad it worked – thanks so much for taking the time to build one! (Good luck with the chores too!)
Looks great and I would like to build one. Do you have a parts list, circuit diagram and code you can share?
Erm, it’s all in the post if you read it!
Wow.
I have been working on a PCB layout, I should have something to post by the end of this week.
Just need to get one made or for someone to have one made to confirm all works, for the present I left the pong clock powered by USB, as on my PCB there is no voltage regulator or no voltage protection, it would be far too easy to destroy the Atmega 328. I wouldn’t take much for me to change the PCB to a DC Jack, but then there is the issue of polarity.
Hey Gary, that’s great news. You might want to talk to Kirby on here as he was also having a go at a PCB and trying out voltage regulators. Can’t wait to see what you come up with.
Hi Nick I have a finished (revision 1) of the PCB, it has not been tested or made yet. what would be the best way of posting the pdf files ?
Hey Nick,
After your help getting it working and putting it together, I noticed a few things in the pong display and was wondering if you or anybody else has made these observations.
1. The left paddle will occasionally miss the ball when it is not the minute mark, another ball appears and then the left paddle will miss again in a few seconds and the minute score will update,
2. The right paddle will occasionally miss when it is not on the hour and another ball will appear and the game will continue with no change in “score”. When it is the hour mark the right paddle misses and the score updates.
3. The left will occasionally NOT miss on the minute mark and the ball keeps bouncing back and forth until the next minute mark at which time the left paddle misses and the minute score updates by 2.
I have seen all of these things happen often and was wondering if I have another problem or if these are “features” needing a tweak?
Hey Paul, I’ve seen 1 and 2, but not 3. You are correct there are erm ‘features’ at the moment. I can’t remember I coded it so long ago but I think I pick a random point on the balls journey toward the bat, then work out where it will land, and move the bat toward it. I suspect sometime the bat doesn’t make it in time, i.e. I’ve assumed the bat can always make it, but on some random picks the calculation is made too late or the ball is going too fast.
When (if) I get time I’ll have to poke through it all, or feel free to investigate!
Thanks Nick…. Thought I was seeing things there for a while… ;)
When and if I ever get my coding up to speed I might just try and see what I can do.
Still a great project… glad you made it and am very happy with mine. If somebody else looks at it and mentions one of the features I’ll just say… “Hmmm, that’s funny are you sure?” Since they happen randomly, I might just get away with it…. LOL
Paul
Hi Nick, just saw your message requesting an all in one PCB for your clock… funny tho that your clock was my very first project with arduino, PCB designing and making… so I have a version of your work that is all on 1 homemade PCB… if you are still interested, give me a shout
Hey Rob, glad you made the clock – love to see the all in one PCB you have. Gary – few comments up (down?) has also designed one thought not had anything made yet.
check your mail ;)
Hey again, I have been playing around with the new version of the code, I love it but I miss something … back in the days when I built that clock, I switch from your code to Wolf’s Spoor ( ) because I really wanted to have the space invaders mode on my clock…. any chance that you try to incoprorate this mode into your code ?? I went back to Wolf’s to ask him aswell, but it doesnt seem to be active on this project anymore … could you try to insert it in your next version of the clock ?? (my programming skills arent good enough to do so .. I’ve tried, but I end up with bugs, glitches and all ^^)
be carefull tho if you try, you need to use the font that’s included in the tar.gz otherwise it wont work
Thanks in advance
PS : check your actual code, line 1953, you put “bool” instead of “boolean” … it may be the reason why some ppl experienced glitches on the 31st of January … just my 2 cents ^^
cheers ;)
Hello.
Today when i opened my eyes, my clock is again on Friday 31 January.
What happen, what should i do? Have you already seen this problem?
Regards.
Jerome
Hello.
Yesterday i didn’t set the day. Today the clock display Saturday 32nd.
Very strange.
Oh I’ve never seen that before. Are you running the latest firmware? If you upload that again it should reset everything.
Yes it’s the lastest firmware.
You know what – mine is the same, only I didn’t notice as I had it in random mode. It’s an error in slide mode – the 3 from the 31sst doesn’t get cleared from the display for some reason so it appears as 32. If you change mode or change back to slide mode it goes. I’ll have to look into my dodgy programming some point and issue an update. Sorry about that! Nick
Ok.
I push the button to display the day and when the program came back in slide mode, the number of the day is ok.
Has anyone thought about creating a laser cut case for this? I was thinking about designing one once I had built my clock. I was thinking ABS plastic sides then clear perspex front?
Yes I was thinking of getting one made at one point. I wanted an opaque white diffuse plastic box – the kind that looks white until the LED lights up behind it. Be interested if you come up with something.
Yeah diffused sounds great, well ill build mine first then once I have something to measure off ill start designing!
Cool, look forward to what you come up with!
I’m discovering this exciting project! Very thank you to you to share your work.
I wonder if you know about the real power consumption. Of course it depends of how many leds are on at a certain moment but we can measure an average and a peak. According to the specs, I though about something like 50 mA for the Arduino and 100 mA for each led panel. But you talk about a power supply of 150 mA, is it really enough?
My idea is to supply power with batteries.
Regads,
Matock
Hey, thanks for the interest. I’ve never measured power consumption, I picked 150 mA as that was the USB PSU I had and it worked. I think you’d need quite a powerful battery to keep it running for any length of time. I don’t know of any LED clocks (even the 7 segment ones) that run of batteries for that reason.
If you really needed batteries, maybe you could implement something in the code that only lit up the display when you pushed a button.
Yes sure, but displaying Pong IS the funny goal. I calculated that even with optimistic consumption, big batteries won’t be alive for more than 10 days!
I definitively will use a wired power supply.
Thx a lot.
j’ai fait aussi une horloge avec le méme type de matrice que toi sauf que j’aimerai afficher la température a la place des “ND” ou “TH” dans le mode normal , j’ai in capteur LM35 sauf que je n’arrive pas a faire afficher ma valeur de mon capteur , a chaque fois que j’essaye les matrice m’affiche rien pourtant le code et bon mais je ne sais pas comment on fait pour que ma valeur soit afficher sur la matrice , si tu a un conseil je le veut bien
merci et en tous cas encore une superbe idée ton horloge c’est du bon boulots :)
I also did a clock with the same type of matrix as you except that I’d like to display the temperature instead of “ND” or “TH” in normal mode I in sensor LM35 except I don ‘happen to do not see my value of my sensor every time I try the matrix shows me nothing though the code and good but I do not know how it’s done for my value is displayed on the matrix, if you have advice I willing
thank you and certainly still a great idea your clock is good jobs :)
Hey, really hard to say what’s wrong -especially when you say your code is correct. I’d try adapting one of the very simple functions like the one that shows the version when the clock starts up. See if you can get it to print the temperature digits there. If that works, you can transplant the code to the clock functions that are a bit more complex. Good luck with it
Hey, that sounds like a whole new project. Unfortunately I don’t have time to do the research for you. Maybe ask on the arduino forums.
thank you
Соглашусь с вами. Тут не все так просто.
Hi Nick thanks for a super project
would it be possible to _ dimm the clock at night with a sensor
Hey, I don’t see why not. I’m sure there are snippits of code you could use that check a light sensor. You’d just have to convert the range of numbers that it produces into the 0-15 range I use for brightness in the clock script.
Then put a brightness check in so it gets called every so often. Maybe stick it in with the get_time() function.
Nick
hey Nick
my watch does not run in ver. 5.1 all text will are different, only the digits displayed correctly
run perfectly with ver. 5.0?
can you help?
Hey, you need to replace the libraries with the new ones – specifically font.h
hello again
it worked thanks for the help
now I’m trying to change the clock to Danish. so now there is a copy in Denmark once again thank you. J
Great, I’ve made it clearer on the page that you need to replace the files.
Nick
Hi nick,
Great job, as always ;)
quick question : what about the All in one PCB… are you still working on this ??
quick question # 2 : any chance to see the Invaders from Wolf’s clock () any time in your version, since he doesn’t seem to be active on this project anymore and his version was based on your work? It would be awesome :)
Anyway, thanks for this great project and for all the updates you ve done in the past couple of years to make it even better, everytime ;)
cheers
Hey, One of the guys on the comments here was working on a board, he was doing a few tweaks last I spoke to him.
I did try and put invaders mode in, but I couldn’t get it to work. I’ll have to have another look at the code. The icons are in the new font in 5.1, just it used yet!
hey nick
I changed my watch to Danish but Danish has three letters more of the alphabet (æøå)
these letters can i add them too the front.h labery ?
and how?
best regarts j
Hey, I’ll try and explain…
The 5×7 characters are stored in font.h as hex in the myfont array – the first array listed. There are 5 hex values per letter, one hex value for each column of the character. If you convert a hex value to binary (e.g. using an online calculator) that gives you the pixels in the column. E.g. for the letter A the first hex value is 0x3F which converts to 00111111 which is the pixels for the left hand column of the A. (The right hand bit in the above being the top left pixel). As the letters are 5×7 and the hex values 8 bits, the first bit isn’t used and is always 0.
So you’d need to design new letters, split them into columns of 1s and 0’s and convert to hex. Then add them to font.h at the end of the myfont array, and update the number of chars in the array at the top of the font.h file from 80 to 83.
After that you need to alter the main code in the ht1632_putchar and slideanim functions. Add more “else if” lines for the new chars. E.g.
else if (c == ‘æ’) {
c = 80;
}
else if (c == ‘ø’) {
c = 81;
}
etc…
Hope this makes sense!
Nick
Will the clock work using a Mega 2560 instead of an UNO?
Yeah should do. You’ll need to lookup the pins on the Mega and adjust them in the sketch code accordingly though.
Hey,
First of all I wanted to say thank you for this project, I have used it as base for my 2nd year uni project I have just about finish this project and for the uni requiremnts I have to made PCB and power supply in order to create it all in one unit, also I have added another mode to display short message as my girlfriend request it haha.
Looks pretty cool I will make and upload video later as it is late now, I have all of the schematic and PCB files if you want to include them.
Good luck and thanks again
Rafal
Hey, really glad you like it and it helped out your Uni course. Be great to get the schematics to share with people! Love to see a video too. Nick
Hey, I built the clock a while ago and now I am leaving it on to run and after a while the displays start glitching. There will be LED’s that are on that are not supposed to be on or LED’s that are off that are supposed to be on. Any ideas whats going on and how to fix it?
Hard to say, could be dodgy power. Maybe try another supply. Also check there aren’t any loose wires or anything shorting out the arduino pins
Hi Nick, Hi all,
I made a fork in your code with a French translation of your Pong Clock. The starting point was the 5.1 but I added many features and fixes:
*…)
I called it 5.1FR. Here is the download link.
And again very thank you to you for this fantastic work and to share it with us. I hope that my little contribution will interest French readers.
Amis bricoleurs, à vos claviers !
Enjoy,
Matock
Tags: French translation, traduction Française
Hey, thanks so much for all the hard work on this, sounds fantastic & cant wait to load this up!
Hey,
I didn’t get a chance to say -but your version looks great. My French is a little rusty but I managed to find my way around! I’m sure you’ll get a few people wanting it translating back to English so they can use the extra modes. I’ve added it to the main article page so people can find it.
Thanks again!
Nick
First of all, thank you Nick to push my work on the center stage!
Well, the English (re)translation shouldn’t be so hard even if you don’t speak French. I started from your English version so it would be easy to revert back the original language by comparing the code. Moreover, I use to program in English, so my code is commented in English, not in French.
The main differences are in the word_clock() function (just words() in mine), because the way to write numbers in french are so different, that I totally rewrited the function. So it would be better to just revert back the original function.
But if somebody is blocked, of course I can help.
Matock
Hi Matcok, thank you for this version for the Pongclock its greatly appreciated. Unfortunately i have struggled to translate it into English. I’m a complete novice when it comes to programing the Arduino. Would it be possible to make the v5.1EG available.
Thanks again for all your hard work.
Hello Matock,
Nice work on this variation of Nick’s wonderful Pong Clock. I have been happily running Pong Clock on my mantel for quite a while, and I was very happy to assist with testing of Nick’s upgrade to the current Arduino IDE compatible version.
It would be wonderful, as Nick mentioned, to have an English version of your work as well.
I have no French language skills at all, but I would be very interested in the extra features that you have so kindly implemented!
On another note, I recently purchased a pair of the very nice and well made 16×24 LED panels that are sold from my favorite Maker Vendor:
These use the same Holtek 1632c controller, and I wired them to the board that I built for Nick’s clock, merely a matter of connecting the correct lines to the connectors which have a different number of pins. It works, and all of the LEDs light up, I can see the correct activity, but the matrices are all out of order, rotated and backwards.
My programming skill are infantile, and even with a little bit of coaching from Nick, I am afraid I am not up to the task of making it work. There is some serious difference in the wiring of the panels, and the libraries that are provided by the kind folks at Adafruit.
Their examples work fine, and I did manage to make a very simple clock code with their libraries.×24+LED#p315202
No where near the great kit that Nick has created. I must say that their font library is also not as good looking as what Nick is using. The large font is really bad etc.
I would love to have a version of the Pong Clock that ran on these panels as an alternative to the Sure displays, which are a bit difficult to get, have a goofy form-factor, and are poorly supported in my experience. I also would be happy to see the additional support for the Adafruit company, as it’s founder has done so much for the Arduino and maker community. And of course, more recognition for Nick’s generous work on the clock would also be a nice thing.
I would be happy to provide a pair of these panels, as I have an extra set, to anyone who would be interested in working on a code translation that would correctly run Nick’s Pong Clock. I would be happy to document the pinouts too, if there was any confusion with that detail.
Peace!
Kirby
Hi!
Inspired by all the hard work here, I created my own clock, in Dutch, based on Matock’s French version, and added a IR receiver to pin 8 to switch modes remotely with a el cheapo remote control (dx.com). To realize this, I had to trim down the size of the IRremove library, which I included in the zip-file
I’m a little novice in programming, and there are still some small bugs around, but hey :-))
Excelent there is no limit.
My next idea is to add an ‘Automatic’ mode for the brighness menu, with a photocell, to adjust brighness automatically according to the ambient light.
Very easy to do with just just one photocell and one resistor (ex.), one analog input port, and a little bit of coding of course..
But unfortunately I have no time currently.
Matock, i find the FR version of the clock awesome….But i wanna use the arduino mega instead of the uno to have more memory to add some more clock modes. In your Fr code, in the Slide mode the digits refresh from above to under…. if i want to let them slide from under to above, what i need to change on the code? Can you help me with that? Big thx fot that….sorry for my english.
Hi Nick,
thanks for all your hard work which has enabled all us “Gadgeteers” to build this great project.
This is my first Arduino build and although I’ve got the clock working, I do have a query as my DS1307 doesn’t seem to be being read. I have used a DS1307 RTC module like you have used on your other clock project, – my question is, does the code need to be adjusted in order to use this module because as far as I can see the actual connections to the arduino uno are the same as what you have done on this clock?!
Any advise would be greatly received.
Cheers and “happy new year”
Mick.
Hi Mick, should be the same – its just the same chip on a daughterboard normally in those modules. Make sure the battery is connected ok too.
If not there are some simple example sketches you can download from a quick google that try and read the clock so you can test ot
Hi Nick, thanks for your reply. I stripped it down completely this morning and remade it. 3 of the ds1307 modules were not keeping the time when I unplugged the clock from the power and plugged it back in again. I tried a 4th and it seems to be ok, I also tried a ds3231 module and that seems to be fine – saying that, none of the modules are making the LED blink in front of pin 13, and I’ve tried it on 4 different Arduino Uno’s! – so I’m baffled there.
Do you think that an Arduino Nano would be man enough to be used on this clock?
I’ve ordered the components to have a go at making your mini LED clock, so I’m looking forward to having a bash at that.
Also tried to load the French space-invader code but I could get past the verifying step, keep getting the message “myfont was not declared in this scope”, but might have another look at that later, although I do struggle with the coding (-:
If and when I’m completely up and running I’ll send you some pics of my efforts.
Thanks again Nick,
Cheers
Mick.
Hi Nick, think I’ve sussed out the French code problem (-:
Cheers
Mick.
great project, Are you the same guy who made the Matrix movie effect on sure electronics module ?
No not me, I’ve not seen that!
Hi Nick and everybody else,
I build two clocks based on your design and code, so pong “awesome_clock_counter = awesome_clock_counter + 2” ;) .
There are some things in the code that I would like to fix:
Sometimes it looks likes the bat misses the ball (when the ball travels relative straight across the field and the bat hits (or should hit) the ball on the corner of the bat).
I also fixed a bug that the clock runs one minute behind (this bug is also in Matock’s version is called 5.1FR):
“//if coming up to the minute: secs = 59 and mins < 59, flag bat 2 (right side) to miss the return so we inc the minutes score
if (rtc[0] == 59 && rtc[1] 0) {
bat1miss = 1;”
We will never run a minute behind. A con is that, at most the ball travel time takes 4 seconds to ping, pong across the field. E.g. the clock runs at most four seconds behind (depending on ball postion and direction on the field).
Hey, the clocks look awesome – I love the cases. Really glad you made them!
If you want to send me an updated sketch with the fixes in, I can post here for others.
Cheers
Nick
Hi,
The cases are really cheap Ikea frames =>
For the 5mm LED displays.
And this one for the 3 mm LED displays:
I think it’s a perfect fit, especially with the passe partout. I drilled some holes in the side of the frame for the two buttons, it really looks cool (of course this is my opinion).
Because I used HTML code in my previous post the important part is missing:
The clock could run a minute behind if this statement is true while the ball is close to the line and so crosses the line at 59 seconds. In that case the clock won’t update because at ‘restart’ it’s still ’59’ seconds. And so the clock gets updated with the old value and so runs a minute behind.
This is the original code:
// if coming up to the minute: secs = 59 and mins < 59, flag bat 2 (right side) to miss the return so we inc the minutes score
if (rtc[0] == 59 && rtc[1] < 59) {
bat1miss = 1;
The fix is:
//;
We will never run a minute behind. A con is that, at most the ball travel time takes 4 seconds to ping, pong across the field. E.g. the clock runs at most four seconds behind (depending on ball position and direction on the field).
I will post my (small) edits soon (still applying some minor edits).
So thank you very much for this great project!
Hi Mr. Breaker,
I saw the same problem in my clock a couple of times. I want to update the code with your fix, but I don’t seem to get it right e.g. make it compile.
I can’t swap the original code:
// if coming up to the minute: secs = 59 and mins < 59, flag bat 2 (right side) to miss the return so we inc the minutes score
if (rtc[0] == 59 && rtc[1] < 59) {
bat1miss = 1;
For the updated code:
//;
It seems I'm missing something..
Hello partners.
I do some day the projector “Mini Led Clock” and now I’ve settled on this that looks great.
My question is that when compiling I get this message:
Low memory available, May stabillity problems occur.
Although it appears that record successfully, I have not tried that yet I need parts for the project.
Thank you very much, and forgive my English
I’ve not seen that error before. Does your arduino have 32K RAM? Are you set to use the right board in the compiler.
Fantastic clock! I recently built one of these with a few changes. I used one of those Arduino Nano clones that is much smaller and only cost $2.20, and I used a DS3231 clock module to improve accuracy. I modified the code slightly to turn random mode on by default but I plan to make all these settings non-volatile. It also needs a way to set the seconds, perhaps I’ll just try to add GPS sync. These are totally cool and very innovative, I plan to build a few more of them to give to family members as Christmas gifts.
I’ve noticed one bug so far but have not had a chance to look closely through the code. Three times now I’ve caught it not advancing the score in pong mode and it ends up behind until the next minute when it advances by two minutes and is then correct. This has occurred at random times, not at the top of the hour.
Great you built it! Those improvements sound cool. I think someone else spotted that bug, they were possibly going to send me a fix but I don’t think I got it. You might want to have a read through the comments here for it.
Any chance you could send the updated code for the DS3231 clock module?
I’m having trouble getting the code to compile with the 1.6.5 engine.
I don’t think I have this. Someone else posted it I seem to remember.
Hi Nick,
Haven’t looked at my pong clock since late 2012 believe it or not. Not because it isn’t cool but loads of life stuff happened lol. I have just looked over the code as it stands and I have to say I like this a lot
“if (! ds1307.isrunning()) {
Serial.println(“RTC is NOT running!”);
ds1307.adjust(DateTime(__DATE__, __TIME__)); // sets the RTC to the date & time this sketch was compiled”
Very swish :) At the time I was messing about with it, I got some limited animation running but it was a bit buggy. Going to take it up again but I think I’ll chuck everything I wrote out and start again. Thanks for the project and all the late nights it has (and will again) give me :D
Having my first go at this, ordered all parts that just arrived, thought I would test the software first.
On a Mac Latest OSX 10.11, Arduino 1.6.5
Imported libraries etc as per instructions, wont compile….
In file included from pongclock5_1.ino:45:0:
/Volumes/Macintosh HD 2/Users/Documents/Arduino/libraries/Font/Font.h:4:35: error: variable ‘myfont’ must be const in order to be put into read-only section by means of ‘__attribute__((progmem))’
unsigned char PROGMEM myfont[80][5] = {
^
] = {
^
Hi, Can you go into the libraries folder and open font.h with textwrangler or similar.
Edit the 4th line so it has the word const in:
unsigned const char PROGMEM myfont[80][5] = {
Then do the same for the other line numbers mentioned – 94 and 108.
Nick
Great, fixed first error…. now do I do the same for the others?
] = {
^
Yep, same for the others
Fixed it, on to the H/W Build…. Thanks
Built, operational… a few Display challenges… had to walk away a few times…
Thanks, great project…. would love to add temp to it, and it cycle temp display….
Now, if I could only find a way to send you bitcoins I would…. just spent an hour and a bit confused… will keep trying!
Yeah I know the walking away thing! Glad you got it built!
Temp display might not be too hard, I think there are arduino projects out there that read from a probe. Then you’d just need to add to the clock mode a new page that shows the temp in digits… might take a bit of playing around but shouldn’t be impossible!
This is still one of my favorite! Thinking about the two color LED boards…or maybe the 3… but this one is always going to be the bomb! Thanks again for this!
Just wondering, anyone out there built any form of mounting / case that you could share design for?
Hi all,
I am trying to work out Andy’s version (RGB Pong Clock), now realize that probably it was a bad idea for first project :-) but I definitely need help.
I am using a MEGA and following adafruit’s tutorial, I can run the demo succesfully.
So, looks like MEGA is communicating with RGB matrix, no problem.
But, I get an error when trying to verify Nick’s or Andy’s scetch, following their specific instructions.
Nothing works out.
initially I was getting an error “no such file or directory”
Fixed this, but now I get “variable ‘noise’ must be constant” etc..
I could probably figure out the solution, maybe it will take 6 months.. :-)
Would appreciate anybody stepping in, to help.
Maybe contact via mail, so I can relay the exact errors and hopefully correct this, without using the thread’s space here.
Mine is temeterson at yahoo.gr. Any help welcome
Regards
Peter
Don’t be lazy Peter ;) The fun is in the troubleshooting – that’s where you learn.
Already started using my 6 months probation time. Thanx
Hi Nick. Thanks for the great clock!
Couldn’t resist adding this clock to my collection.
I have added PIR control to turn the displays off when no one is in the room, master Clock sync, a DS3231 module, remote control and a few other tweaks.
I have just started to put the design on my clock site here.
I have added credit to you and links to your site. I hope this is OK?
Regards.
Brett.
Hey Brett, that’s absolutely fine, your clock looks awesome in the white frame and the extra features are very cool. Glad you are are keeping the project alive!
Brett, this looks brilliant..
Some of the things I had “planned” to do with the code and share… time poor my side…
BTW the links on your site dont work… was trying to take a look at the code…
The page is still “work in progress” much more to follow soon…………..
I have put a note saying this on the link to this page but will add it to the page itself as well.
Can anyone tell me if digispark atting85 would replace the arduino here ?
Hey Sam, might do. The clock needs 5 I/O pins – 3 for the displays and 2 for the buttons so you’re OK there. Then it needs i2c which it says is provided by UCI – i’m not sure what that is so you’d have to investigate, and also change the pins allocated at the top of the code to whatever pins you choose on the attiny.
Hi Nick, great project. I’m in the process of constructing my own. One point – adding “const” to the start of lines 2212 and 2271 squash a couple of warnings with the latest version of Arduino compiler (1.6.8).
I’ll post a picture of the completed clock when I’m done.
Cheers!
Alexander
Ah thanks Alexander. It seems every release I have to change the code to work with the latest IDE. I’ll try and update it again when I get time!
Thank you very much, nice watch. The only problem is delayed, any solution? Thank you and sorry for my bad English.
Sorry, I don’t understand what you mean by delayed
My clock slow down three minutes in the week
Ah, I had this too. I replaced the crystal and it fixed it. (The first one I got was a cheap one from eBay)
OK thanks
Nick
Still enjoy my clock and have made a mod to show room temperature as well.
I’m thinking of making an arduino shield pcb that I would put in the community so make it easier to put together.
Would you be open to sharing the schematic to save me starting from scratch?
Many thanks
Hey, I don’t really have a schematic – I just wired it as per I wrote in the blog! If you want to make one there go for it!
Hi… will do, it was this I was after. what did you use to build this? Thanks :)
Hi the link you have pasted is from my site brettoliver.org.uk . I have built a version of Nick’s Pong Clock that is synchronised from a Master Clock every 30 seconds and has PIR controlled display blanking to save power. The circuit probably has very few changes from Nick’s original.
The circuit is drawn up with Livewire
It’s a very basic and very easy to use circuit design and simulator. I can send you my livewire drawing file of the circuit if you do get the software.
#Embarassed Oliver :) sorry Nick, got mixed up!
I have built based on your design Oliver, modded a bit and now want to build an all-in-on Uno Shield with RTC Clock and my temperature mods and nice socket to plug the display in.
Plan to share it in open source, if you could export the drawing in anything that could be imported by then thats fantastic, if not, i’ll give it a crack! Just trying to get a head start!
No worries – glad you found the schematic! The mods sound great. Be fantastic if there was a proper clock shield for people to use.
Hi I had had a look at easyeda and it can’t import Livewire files. Livewire will only export in it’s native format so you will have to start from scratch:(.
Will be interested in you final design with Temperature mods.
Regards. Brett.
Here’s my adaption of the code (credits to Nick and Oliver) –
Displays Temp, but lots of code tidyup required, and now outgrown a UNO, needs Leonardo – would love help to fix that!
Am building a Shield to make this easy to assemble, in meantime found this×32-rgb-matrix-panel-with-an-arduino-uno-shield/ and may either adapt code or continue building my shield with embedded DHT22 / Other Sensor.
Feel free to help here, was my first real Arduino Project!
Hi,
Is there any difference if I use a smaller matrix like two matrix of 8×8?
Should I change too many connections?
Thanks, for sharing a great project like this :)
Use the matrix i have – there are 3 or 5mm led versions. If you pick something else it may be completely different and not work
Excuse me does these matrix work for the project:
I may use 2 of these 8 x 32 modules. Are there to many changes to do to the connections and at the code?
thanks…:)
They are the wrong number of pixels for a start… So no they won’t work without a lot of changes
Even with 2 of them out will mean a lot of changes. If you are not confident with it I’d use the ones I recommend.
today, on the french version, we have a Christmas cheers every 15 minutes !
Hi Nick,
Could you send me the link on ebay where you bought the clock chip kit? There are different types and I’m not sure which to buy…
Hey I can’t remember but just look for Ds1307 with crystal and coin cell. Or try Sparkfun or adafruit or cool components
Is this kit compatible?:
Thanks
Yes that’s it. You’ll need the battery too. Some places dont ship them. The clock won’t work with no battery.
You want to use a DS3231. It’s al lot more accurate / significantly less drift.
True, I’ve not tried it myself but others have had good results.
Thanks.
But how do I connect it?
Obviously, you will need to solder 4 wires to the plate through holes on the board that the link refers to. The signal line names are the same, and the voltage connections should also be self explanatory. Actually, having all of the items (battery, battery holder, RTC chip) on a single board makes it easier to integrate into the design. You just need to solder 4 wires that connect to the appropriate connections on the rest of the Arduino hardware.
Do I have to change something to the code?
Thanks in advance…
There are no code changes to use the DS3231 real time clock module.
Have just completed my 2nd Pong Clock.
I have added a temperature display in my favorite Slide Mode. I have also changed the Random mode to just show Slide then Pong every few set mins and seconds.
I have also added a countdown timer that plays a choice of MP3 sounds when the timer runs out.
The timer is built into the Normal mode.
I’ll add full details as soon as I can on my site
Brett, loving v7.5… I’ll trash my poor version with Temp. One thing… that I really want and would love your “guidance” on is how to alternate the Temp / Date display on the Slide Mode… thats what I “REALLY” want :)
Hi Anthony. Glad you like my new version.
If you look at the code line 2261 “void slide()” the code for the temperature display is in there. I suppose to add an alternating date display as well you could call the date at set seconds as if you pressed the date button I think button “B”. This would display the date then revert back to time and temperature. You could call this using the code in line 3169 “void set_next_random()” as an example and call “display_date()” every say 30 seconds.
Version 2 Pong Clock Video
Here’s a link to a video showing the temperature display and various modes the ticking sound is from another clock in the same room synchronized to the same Master clock
As there seems to be some activity again here :) my adaption is here : with Temperature…. but some issues to address… ;-)
Sorry for my bad English.
Someone who can add the time change (DST)
Thank you
this is one of the best Arduino projects i ve seen on the net..thumbs up man.. | https://123led.wordpress.com/about/ | CC-MAIN-2017-22 | refinedweb | 30,604 | 81.22 |
I tried it here with android. It works, no segfault. I have used llvm-3.2, maybe that helps? On 01/24/2013 03:44 PM, Stephen Paul Weber wrote: > I just got my unregistered LLVM-based ARM cross-compiler to a working > place, which means I can produce any binaries which do no crash. Yay! > > However, <> when I try to > use FunPtr wrappers, something smashes the stack. > > Would others working on ARM cross-compilers be willing to try this test > and see if it works for you: > > {-# LANGUAGE ForeignFunctionInterface #-} > module Main (main) where > > import Foreign.Ptr > > foreign import ccall "wrapper" wrap_refresh :: ( IO ()) -> IO (FunPtr ( > IO ())) > > main :: IO () > main = do > wrap_refresh (return ()) > return () > | http://www.haskell.org/pipermail/ghc-devs/2013-January/000139.html | CC-MAIN-2014-23 | refinedweb | 113 | 75.2 |
This example demonstrates the use of a timer to periodically update a user interface.
We import the classes and modules that will be needed by the application. The most relevant are the classes from the android.os module.
from java.lang import Math, Object, Runnable from java.util import ArrayList, Timer, TimerTask from android.app import Activity from android.content import Context from android.graphics import Bitmap, Canvas, Color, Paint from android.os import Bundle, Handler from android.view import MotionEvent, View
The TimersActivity class is derived from the standard Activity class and represents the application. Android will create an instance of this class when the user runs it.
class TimersActivity(Activity): __interfaces__ = [Runnable]
The activity implements the Runnable interface from the java.lang module. This requires us to implement the run method.
The initialisation method simply calls the corresponding method in the base class.
def __init__(self): Activity.__init__(self)
The onCreate method is called when the activity is created. We call the onCreate method of the base class with the Bundle object passed to this method to set up the application.
@args(void, [Bundle]) def onCreate(self, bundle): Activity.onCreate(self, bundle)
We create a Handler object that enables us to schedule events so that we can arrange for regular timed updates. This may not be the most optimal way to try and perform animations with a certain number of frames per second.
self.handler = Handler()
We also create a custom view that is used as the main view in the activity.
self.view = DrawView(self) self.setContentView(self.view)
When the activity starts or is navigated to by the user, the onResume method is called. We call the corresponding method in the base class before requesting a message to be delivered after a 25 milliseconds delay.
def onResume(self): Activity.onResume(self) self.handler.postDelayed(self, long(25))
When the user navigates away from the activity, the onPause method is called. We call the onPause method in the base class and remove any pending message callbacks from the message queue. This prevents messages from being delivered when the activity is inactive.
def onPause(self): Activity.onPause(self) self.handler.removeCallbacks(self)
Since we declared that the activity implements the Runnable interface, we need to define a run method that will be called when a message, sent using the Handler's postDelayed method, is delivered to the activity. Our implementation simply updates the custom view and requests a new message so that another update can be performed 25 milliseconds later.
def run(self): self.view.update() self.handler.postDelayed(self, long(25))
We define a Point class to represent points defined using polar coordinates.
class Point(Object): __fields__ = {"radius": double, "angle": double}
Instances of this class contain two attributes that other objects need to access, so we define these as fields in order to make them accessible.
The initialisation method accepts two doubles for its radius and angle parameters which we store in the corresponding attributes.
@args(void, [double, double]) def __init__(self, radius, angle): Object.__init__(self) self.radius = radius self.angle = angle
We also define a PointArray class, using the standard ArrayList template class. This enables us to create arrays containing instances of the Point class we defined above.
class PointArray(ArrayList): __item_types__ = [Point] def __init__(self): ArrayList.__init__(self)
The item type held by the container is defined using the
__item_types__
attribute. This attribute is only used at compile time. The
__init__ method
only needs to call the corresponding method in the base class.
The DrawView class is derived from the standard View class and is used to show custom graphics in the activity.
class DrawView(View): PI_2 = 6.283185307179586
For convenience, we define a constant to hold the value of 2 * pi. This is only used at compile time, so we can't use values from the Java standard library.
As with other views, the initialisation method accepts a Context as its parameter and initialises itself by calling the initialisation method of the View class.
@args(void, [Context]) def __init__(self, context): View.__init__(self, context)
We define two Paints that we will later use to draw the view's background and foreground decorations.
self.background = Paint() self.background.setColor(Color.BLACK) self.foreground = Paint() self.foreground.setColor(Color.WHITE)
We also create an instance of a PointArray in which we store Point objects. These points will be used in the onDraw method to draw foreground decorations in the view. We add one to ensure that something is shown when the view is displayed.
self.points = PointArray() self.points.add(Point(40.0, 0.0))
Note that the use of the PointArray class is only necessary if we do
not wish to assign items to the instance since we need to specify type
information for it. In the above code, we could simply write
self.points = [Point(40.0, 0.0)] instead.
The onSizeChanged method is called when the view is first shown and whenever it changes size afterwards.
@args(void, [int, int, int, int]) def onSizeChanged(self, width, height, oldWidth, oldHeight):
We record the coordinates of the centre of the view as attributes of the view, as well as calculating a reasonable size for the circles we intend to draw on it.
self.ox = width/2 self.oy = height/2 self.bs = Math.min(width/50, height/50)
The onDraw method is called when the view needs to be displayed. The parameter is a Canvas object that we draw onto. We call the onDraw method in the base class before adding our own decorations.
@args(void, [Canvas]) def onDraw(self, canvas): View.onDraw(self, canvas)
We fill the background with the Paint that we defined earlier.
canvas.drawPaint(self.background)
We iterate over each point in the list held by the view's
points
attribute.
it = self.points.iterator() while it.hasNext():
For each point, we obtain its position relative to the centre of the view and draw a circle with the radius calculated earlier.
p = it.next() r = p.radius x = self.ox + r * Math.cos(p.angle) y = self.oy + r * Math.sin(p.angle) canvas.drawCircle(x, y, self.bs, self.foreground)
If the point happens to be at the centre of the view, we remove it from the list after drawing it.
if r == 0.0: it.remove()
The onTouchEvent method is called when the view receives touch events. We are only interested in events that inform us that the user has touched the view.
@args(bool, [MotionEvent]) def onTouchEvent(self, event): if event.getAction() != MotionEvent.ACTION_DOWN: return False
We ignore any other kind of event, returning False to indicate that we did not handle the event.
For the touch events that we handle, we convert the coordinates of the
touch from the view coordinate system to the polar coordinate system
used by the Point class, and we add a Point to the
points list for
display.
x = double(event.getX()) - self.ox y = double(event.getY()) - self.oy r = Math.sqrt(Math.pow(x, 2.0) + Math.pow(y, 2.0)) a = Math.acos(x/r) if y < 0.0: a = DrawView.PI_2 - a self.points.add(Point(r, a))
We return True to indicate that we handled the event.
return True
When each update message is received by the activity, its run method calls this method of the view.
def update(self): i = 0 l = len(self.points)
We simply iterate over all points in the list held by the
points
attribute, changing the angle of each and decreasing its radius towards
a minimum value of 0.0.
while i < l: angle = (self.points[i].angle + 0.06) % DrawView.PI_2 self.points[i].angle = angle radius = Math.max(0.0, self.points[i].radius - 0.5) self.points[i].radius = radius i += 1 self.invalidate()
Finally, we invalidate the view to ensure that the onDraw method will be called, updating the contents of the view to the user. | http://www.boddie.org.uk/david/Projects/Python/DUCK/Examples/Serpentine/Timers/docs/timers.html | CC-MAIN-2017-51 | refinedweb | 1,331 | 59.4 |
couchdbkit 0.4.3
Python couchdb kit
About
Couchdbkit.: Here we use contain to associate the db to the Greeting object. This function could be use to associate multiple dcouemnt objects to one db:
contain(db, Doc1, ...)); }
A system will be provided to manage view creation and other things. As some noticed, this system works like couchapp.
Then we use FileSystemDocsLoader object to send the design document to CouchDB:
from couchdbkit.loaders import FileSystemDocsLoader loader = FileSystemDocsLoader('/path/to/example/_design') loader.sync(db, verbose=True)
- Topic :: Database
- Topic :: Software Development :: Libraries :: Python Modules
- Topic :: Utilities
- Package Index Owner: benoitc
- DOAP record: couchdbkit-0.4.3.xml | https://pypi.python.org/pypi/couchdbkit/0.4.3 | CC-MAIN-2017-43 | refinedweb | 106 | 51.44 |
!
I have an xls file created and i want toopen it add new sheet in existing file and save the xls file is there any one who can help me in this?
Hi Erika,
I am developing an Excel Add-In in Visual Studio 2005 (C#) for Excel XP and higher.
I read somewhere that I need to explicitly release all objects even the Range object that I get from get_Range() method.
What else need to be released in an Add-In ?
regards
Abhimanyu Sirohi
I am having problems with excel reference in my .NET project.
I added reference to Excel object in my .NET application by including Excel 11.0 object library. My app worked fine until the following line was added to one of the classes where the excel operations are performed.
using Excel = Microsoft.Office.Interop.Excel;
When the above line is added the build throws error in my machine saying
I:\Transform\Spreadsheet\ExcelLoader.cs(12): Namespace '' already contains a definition for 'Excel'
If the above line is removed, it works fine in my machine, but throws a different error in my colleague's machine.
Can somebody help me in telling me under what circumstance the above line should be added, and why the .NET environment in my machine is complaining about the line.
Any help is greatly appreciated.
-Siya
Siya,
This article may help
Also Office XP PIA's are available at
I am developing an Excel Add-In in Visual Studio 2005 (C#) for Excel 2007.
I would like to know how to dynamically remove the Excel Cells in Memory.
Thannks,
Ram
Hi,
I m facing one problem
How to Catch Any Excel File Which user opens..
I want to catch that file from my program and if any changes made in that file then i want to save those changes as well as old changes also i want ...
I want to make program in C#.NET or ASP.NET can you help me about this?
Contact me on:
nileshupadhyay10582@gmail.com
Thanks in advance
How i can set the background color for a range of cells?
Thanks
hai friends,
I need help from u. i.e.,How to programmatically generate Microsoft Excel sheets with having dorpdown Lists in some columns through C#.net 2005.
can any one know please tell me the solution
I got to this post by searching for "0x800A03EC". In my case, I had something like:
xlSheet.Cells[0,0] = "a value";
The error went away when I switched this to:
xlSheet.Cells[1,"A"] = "a value";
@Ahmed: it's simple ;)
Excel.Range range = worksheet.get_Range("A1", "I9");
range.Interior.Color = System.Drawing.Color.Green.ToArgb();
Note that the Color property must be set to an RGB integer value, or you will get an exception.
@sfuqua: you got that error because Excel indices start at 1, not 0 as you might expect.
Thus, to get the first (top-left) cell in a worksheet, you would use:
xlSheet.Cells[1, 1] = "a value";
I am developing a web aplication where the user uses a editor to store text on a database. then this information is exported to a excel file.
the problem I am facing is that when I set the text on a cell with new lines, it shows the text on one line and the new line characters are shown as small boxes. I need to show this text as if the user has enter Alt + Enter on the cell and the text viewed on multiples fows on the same cell
Any information will be appreciated
For everyone who is getting the 0x800A03EC exception:
Excel cell indexing starts from 1 (NOT 0), if you try to access a cell like [0,x] or [x,0], the exception will be raised.
I am creating some UDFs (in C# automation) and these are working fine. But i can't put descriptions of the functions and arguments.
Please help me.
Thanks
Mousum
Hi Erika, I have this situation, I need to name, at the moment of the creation, every Sheet in my Worksheet, is that possible? i.e:
...
Microsoft.Office.Interop.Excel.Application excel;
excel.ActiveWorkbook.Worksheets.Add( missing ,excel.ActiveWorkbook.Worksheets[ excel.ActiveWorkbook.Worksheets.Count ] , missing , missing );
///below I'm creating the necessary Sheets in my Worksheet; if the aplication needs 3 sheets, the code below, automatically will generate Sheet1, Sheet2, Sheet3. It is possible to generate it with other names?
I am struggling to obtain argb colors from an excel sheet to store in a database, to be used later.
below is the closest i got but it gives me wrong colors back (vb6 stored a value and it worked, same code in vs2005 errors)
Dim Col As Color
Col = Color.FromArgb(worksheet.Cells(ExcelRow, 4).interior.color.GetHashCode)
Dim a As Byte = Col.A
Dim r As Byte = Col.R
Dim g As Byte = Col.G
Dim b As Byte = Col.B
fld = Format(a, "000") & "," & Format(r, "000") & "," & Format(g, "000") & "," & Format(b, "000")
''''''''''
2nd program
acell = Excel.ActiveSheet.Cells(row, col)
Fld = data1("rowcolor").Value
acell.BackColor = Color.FromArgb(Mid(Fld, 1, 3), Mid(Fld, 5, 3), Mid(Fld, 9, 3), Mid(Fld, 13, 3))
thanks any help appreciated
Erica you are so awesome! I just realized that I was setting my columns at 0.
Thanks,
Carlos.
Can any 1 tell me how to delete a row in excel through .Net(VB/c#)
i've tried with
excl(Excel object).Rows(i).Delete()
but it is giving error
You need to get a range object and then delete the range as below. (I don't have experience delete rows, but this is how I delete cells.
r1.Delete(XlDeleteShiftDirection.xlShiftUp);
Thnks a lot it is very use full for me.....!
Can someone tell me how to format the data in Excel File. For example i have data in the format "0527" in the dataset.But in the Excel file it is being displayed as "527" only. It is skipping the prefixed zeros. Please help
Hi friends,
i want to display the data in asp.net along with cell colors as it is present in excel sheet, plz can any one help me. i'm using c# as code behind.
I hate excel co-ords, so I made this.
Helps with looping...
<code>
private static string ConvertToExcelCoord(int Col, int Row)
{
int c1 = -1;
while (((int)'A') + Col > ((int)'Z'))
{
Col -= 26;
c1++;
}
return (c1 >= 0 ? ((char)(((int)'A') + c1)).ToString() : "") + ((char)(((int)'A') + Col)).ToString() + ((int)(Row + 1)).ToString();
}
</code>
There should probably be a check and an exception if the coords are too big...
I need to insert alt+enter in excel programmatically to show data in separate lines within a cell.
Efrain Juarez asked this as well, but nobody replied so far.
As my friends wrote before me, i need to insert Alt+Enter in Excel to show data in separate lines within a cell.
Anyone knows a solution?
Thanks a lot everybody.
Well, I have de solution to represent Alt + Enter programmatically With VB.NET.
WorkSheet(Row, Column).Value = "TextForFirstLine" & Chr(10) & "TextForSecondLine"
So, Chr(10) represents Alt+Enter.
I hope this solution helps you.
Salutations everybody.
Can you suggest how to create borders around the cells(like a table format) in the Excel.
- Shruthi
Is there a way to filter a field with more than two criteria. In VBA you can specify an array list of criteria and I have been trying to implement something similar in C# with no luck. Below is the VBA example:
ActiveSheet.ListObjects("tableOpenedData").Range.AutoFilter Field:=8, _
Criteria1:=Array("BLT / Desktop Tool", "Delivery", "Editorial"), Operator:= _
xlFilterValues
Any suggestions on doing this in C# would be appreciated.
Thanks!
How to programatically pass ALT+ENTER from c#.net
Can you suggest how to create borders around the cells(like a table format) in the Excel ?
chartRange.BorderAround(Excel.XlLineStyle.xlContinuous, Excel.XlBorderWeight.xlMedium, Excel.XlColorIndex.xlColorIndexAutomatic, Excel.XlColorIndex.xlColorIndexAutomatic);
ttp://csharp.net-informations.com/excel/csharp-format-excel.htm
tks.
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Errors and Warnings
This section lists core errors and warnings that may occur in DevExtreme applications.
E0001
Occurs when a method has no implementation.
E0002
Occurs when a member name collision is detected.
E0003
Occurs when you instantiate a class without using the "new" keyword.
E0004
The NAME property of the component is not specified.
E0005
Occurs when the device on which the current application is running is not in the list of known devices.
Accepted devices are the following: "iPhone", "iPhone5", "iPad", "iPadMini", "androidPhone", "androidTablet", "win", "winPhone", "msSurface" and "desktop".
E0006
Occurs when requesting a Url by the key that is not defined within the EndpointSelector's configuration object.
Check to make sure that the EndpointSelector key of the required URL is included into the configuration object.
E0007
Occurs when the "invalidate" method is called outside the update transaction.
E0008
Occurs when it is impossible to create an action because the type of the passed option name is not a string.
E0009
Occurs when a component is not initialized for this element.
E0010
Occurs when the "from"/"to" configuration property of a slide animation is not a plain object.
E0011
Occurs when an unknown animation type is requested.
Accepted animation types are described in the documentation.
E0012
Occurs when using an old version of the jQuery library.
Please use jQuery version 1.10.0 or greater.
E0013
Occurs when using an old version of the Knockout library.
Please use Knockout version 2.3.0 or greater.
E0014
Occurs when the 'release' method is called for an unlocked Lock object.
E0015
Occurs when a queued task returns an unexpected result.
E0017
Occurs when a namespace for an event is not defined.
E0018
Include a reference to the dx.module-widgets-base.js, dx.module-widgets-web.js or dx.module-widgets-mobile.js scripts to your application.
E0020
Occurs when an unsupported template engine is set.
Acceptable template engines are listed in the description of the setTemplateEngine(name) method.
E0021
Occurs when an unknown theme is set.
Refer to the current(themeName) method description to learn which theme names are acceptable.
E0022
Occurs when the LINK[rel=dx-theme] tags go before DevExtreme scripts.
For details, refer to the Predefined Themes article.
E0023
Occurs when a name is not specified for a dxTemplate markup component.
Specify a name using the name configuration option of the dxTemplate component.
E0100
Occurs when an unknown validation rule type is used.
The predefined validation rule types are listed in the Validation Rules Reference section.
E0101
The value of the min/max option must not be null or undefined.
E0102
The value of the comparisonTarget option must be specified so that 'compare' rule can be checked.
E0110
Occurs when an unknown or unregistered validation group is validated using the DevExtreme.validationEngine.validateGroup(group) method.
Check the valid group key is passed as the validateGroup(group) function parameter.
E0120
Occurs when a default adapter cannot be initialized for the target editor.
Check that you associate the dxValidator component with a DevExtreme editor or with a custom adapter that is set to interact with a custom editor.
See Also
W0000
Appears when a deprecated component is detected in an application.
Use the component that is suggested instead.
W0001
Appears when a deprecated option is detected in an application.
Use the option that is suggested instead.
W0002
Appears when a deprecated method is detected in an application.
Use the method that is suggested instead.
W0003
Appears when a deprecated field is detected in an application.
Use the field that is suggested instead.
W0004
Appears when the timeout that was set to load a theme is over.
To resolve this, do the following.
- Make sure that the CSS files with the required theme are added to the application.
- Make sure that the CSS files have valid links in the application's main page.
For details on themes, refer to the Predefined Themes article.
W0005
Appears when a deprecated event is detected in an application.
Use the event that is suggested instead.
W0006
Appears when a recurrence rule is invalid.
Correct the rule.
W0007
Appears when the Globalize culture script is not referenced on the application page.
To resolve this, do the following.
- Make sure that the Globalize script for the required culture is added to the application.
- Make sure that the Globalize script has a valid link in the application main page. | https://js.devexpress.com/Documentation/15_2/ApiReference/Common/Utils/Errors_and_Warnings/ | CC-MAIN-2017-26 | refinedweb | 733 | 60.31 |
#include <PK_workers.h>
IWLAsync_PK: buffer class for pre-sorted PK integrals. Each buffer class has one IWL bucket for each PK bucket. We pass integrals with their labels to this class, and it stores it in the appropriate bucket. When a bucket is full, it is dumped to an IWL file using asynchronous I/O for storage. When we eventually switch out of IWL to something else, this class will have to be reworked, and also the integral reading from PK using IWL objects, but that is all.
Constructor, also allocates the arrays.
Destructor, also deallocates the arrays.
Filling values in the bucket.
Filling buffer with dummy values and flushing it. Also indicates that this is the last buffer.
Accessor functions.
Popping a value from the current buffer, also decrements integral count.
Actually writing integrals from the buffer to the disk.
Buffer is full, write it using AIO to disk.
Position in bytes for next write.
The AIO Handler.
Are we using buffer 1 or 2?
Number of integrals per buffer.
File number.
Job Ids for AIO.
Integral labels.
Is this the last buffer for PK bucket?
Current number of integrals in buffer.
Integral values. | http://psicode.org/psi4manual/doxymaster/classpsi_1_1pk_1_1IWLAsync__PK.html | CC-MAIN-2019-09 | refinedweb | 195 | 70.19 |
Created on 2007-12-20 19:49 by ijmorlan, last changed 2010-07-21 02:37 by terry.reedy. This issue is now closed.
There appears to be a race condition in os.makedirs. Suppose two
processes simultaneously try to create two different directories with a
common non-existent ancestor. For example process 1 tries to create
"a/b" and process 2 tries to create "a/c". They both check that "a"
does not exist, then both invoke makedirs on "a". One of these will
throw OSError (due to the underlying EEXIST system error), and this
exception will be propagated. Note that this happens even though the
two processes are trying to create two different directories and so one
would not expect either to report a problem with the directory already
existing.
I don't think os.makedirs() can do anything here. It should be caller's
responsibility to check for this kind of issues.
The only thing I found in the bug database concerning os.makedirs was
Issue 766910 (). I realized
os.makedirs had a race condition because in my application I want to
create directories but it's perfectly fine if they already exist. This
is exactly what trace.py in Issue 766910 seems to need.
I started writing my own, which was basically just os.makedirs but
calling my own version of os.mkdir which didn't worry about
already-existing directories, but realized that wouldn't work.
Eventually I ended up with the routines I've put in the attached
makedirs.py.
I think os.makedirs can be fixed by making what is now its recursive
call instead call my version of makedirs. I also think both my mkdir
and my makedirs should be present in the standard library as well as the
existing versions. Possibly this could be done by adding a flag to the
existing versions, defaulted to obtain the current behaviour.
I think we can fix this as follows: whenever it calls os.mkdir() and an
error is returned, check if that is EISDIR or EEXISTS, and if so, check
that indeed it now exists as a directory, and then ignore the error.
Moreover, I'd like to do this for the ultimate path to be created as
well, so that os.makedirs(<existing directory>) will succeed instead of
failing. This would make the common usage pattern much simpler.
I think it should still fail if the path exists as a file though. (Or
as a symlink to a file.)
Patch welcome!
I think this is a feature request and hence should only be fixed in 2.6.
Can you rephrase this as svn diff output?
Also, mkdir() is a confusing name for the helper -- I'd call it
forgiving_mkdir() or something like that.
Yes, I'm really combining two things here - the race condition, which I
argue is a (minor) bug, and a feature request to be able to "ensure
exists" a directory.
I have not produced a proper Python patch before and I have other things
to do so this will take longer than one might hope, but I would be happy
to create a patch. Note too that the file I uploaded is from my
project; I will attempt to make the patch be more appropriate for the
standard library than an extract from my project.
Attached is an svn diff against the trunk. I was looking at os.py from
Python 2.5 not the trunk, and it appears that an attempt at fixing the
race condition has already been put into os.py, but I don't believe it's
correct.
The attached patch renames the existing mkdir to _mkdir, and creates a
new mkdir with an additional "excl" parameter to select
error-if-already-exists or not. It defaults to the current behaviour.
Similarly, makedirs gets the same extra parameter which is passed down
to mkdir.
By simply using the new versions as before, one obtains the old
behaviour unchanged except that the race condition is corrected. By
using excl=False one gets the new behaviour.
I have updated the documentation also but I don't really know what I'm
doing there so my use of the rst format may not be right.
I should add that the new parameter is called "excl" by analogy with the
O_EXCL option to os.open().
Also, I'm not absolutely certain about the test for which exceptions
should be ignored when excl == False:
e.errno == errno.EEXIST and path.isdir (name)
This will not work if errno is set to something other than EEXIST when
mkdir fails due to the directory already existing. The above works on
my system but I can't be certain that all mkdir implementations report
EEXIST.
It should be safe to drop the errno check altogether, and I'm starting
to think that we should; at present it's really just an optimization to
avoid using .isdir, but only in what should be rather uncommon
circumstances. I think the smell of "premature optimization" may be
hard to ignore.
So the if statement would be:
if excl or not path.isdir (name):
raise
Here's the version of this that I've been using for almost a decade now:
Actually I used to have a bigger version that could optionally require
certain things of the mode of the directory, but it turned out that I
wasn't going to need it.
def make_dirs(dirname, mode=0777):
"""
An idempotent version of os.makedirs(). If the dir already exists, do
nothing and return without raising an exception. If this call
creates the
dir, return without raising an exception. If there is an error that
prevents creation or if the directory gets deleted after make_dirs()
creates
it and before make_dirs() checks that it exists, raise an exception.
"""
tx = None
try:
os.makedirs(dirname, mode)
except OSError, x:
tx = x
if not os.path.isdir(dirname):
if tx:
raise tx
raise exceptions.IOError, "unknown error prevented creation of
directory, or deleted the directory immediately after creation: %s" %
dirname # careful not to construct an IOError with a 2-tuple, as that
has a special meaning...
This is again being discussed in Issue 9299.
The precipitating issue for this and #9299 are different: parent race leading to error versus tail existence leading to error. However, both patches address both issues.
See #9299 for my comparison of this patch and that.
I am consolidating nosy lists there. Perhaps most/all further discussion should be directed there.
Isaac, thank you for the report and patch. With more attention, this might have been tweaked and applied a couple of years ago. We are trying to get better at timely responses. | https://bugs.python.org/issue1675 | CC-MAIN-2020-34 | refinedweb | 1,116 | 65.93 |
C Programming/A taste of C< C Programming
As with nearly every other programming language learning book, we use the Hello world program to introduce you to C.
#include <stdio.h> int main(void) { puts("Hello, world!"); return 0; }
This program prints "Hello, world!" and then exits.
And if you want to hold the output and it does not exit, you may use the
getchar(); as following:
#include <stdio.h> int main(void) { puts("Hello, world!"); getchar(); return 0; }
Enter this code into your text editor or IDE, and save it as "hello.c".
Then, presuming you are using GCC, type
gcc -o hello hello.c. This tells gcc to compile your hello.c program into a form the machine can execute. The '-o hello' tells it to call the compiled program 'hello'.
If you have entered this correctly, you should now see a file called hello. This file is the binary version of your program, and when run should display "Hello, world!"
Here is an example of how compiling and running looks when using a terminal on a unix system.
ls is a common unix command that will list the files in the current directory, which in this case is the directory
progs inside the home directory (represented with the special tilde, ~, symbol). After running the
gcc command,
ls will list a new file,
hello in green. Green is the standard color coding of
ls for executable files.
~/progs$ ls hello.c ~/progs$ gcc -o hello hello.c ~/progs$ ls hello hello.c ~/progs$ ./hello Hello, world! ~/progs$
Part-by-part explanationEdit
#include <stdio.h> tells the C compiler to find the standard header called <stdio.h> and add it to this program. In C, you often have to pull in extra optional components when you need them. <stdio.h> contains descriptions of standard input/output functions which you can use to send messages to a user, or to read input from a user.
int main(void) is something you'll find in every C program. Every program has a main function. Generally, the main function is where a program begins. However, one C program can be scattered across multiple files, so you won't always find a main function in every file. The int at the beginning means that main will return an integer to the operating system when it is finished.
puts("Hello, world!"); is the statement that actually puts the message to the screen. puts is a string printing function that is declared in the file stdio.h (which is why you had to #include that at the start of the program)
puts automatically prints a newline at the end of the string.
return 0; will return zero (which is the integer referred to on line 3) to the operating system. When a program runs successfully its return value is zero (GCC4 complains if it doesn't when compiling). A non-zero value is returned to indicate a warning or error.
The empty line is there because it is (at least on UNIX) considered good practice to end a file with a new line. In gcc using the
-Wall -pedantic -ansi options, if the file does not end with a new line this message is displayed: "warning: no newline at end of file". (The newline isn't shown on the example because MediaWiki automatically removes it) | https://en.m.wikibooks.org/wiki/C_Programming/A_taste_of_C | CC-MAIN-2015-40 | refinedweb | 560 | 66.44 |
On Thu, 10 Jan 2019 at 06:43, Alexander Graf <address@hidden> wrote: > > > > On 10.01.19 00:08, Peter Maydell wrote: > > On Wed, 9 Jan 2019 at 17:14, Alexander Graf <address@hidden> wrote: > >> > >> On 01/09/2019 05:59 PM, Peter Maydell wrote: > >>> On Wed, 9 Jan 2019 at 16:52, Peter Maydell <address@hidden> wrote: > >>>> On Wed, 9 Jan 2019 at 15:26, Alexander Graf <address@hidden> wrote: > >>>>> In U-boot, we switch from S-SVC -> MON -> HYP when we want to enter > >>>>> HYP mode. This dance seems to work ok (hence it's there in the code > >>>>> base), but breaks with current QEMU. > >>> PS: it would be helpful if the commit message said how u-boot > >>> is trying to go from Mon to Hyp -- some ways to try to do > >>> this are OK, and some are not, so whether it's supposed to > >>> work or not depends on what u-boot is actually doing... > >> > >> I don't fully understand all of it to be honest :). But the code is here: > >> > >>;a=blob;f=arch/arm/cpu/armv7/nonsec_virt.S > >> > >> What I managed to understand so far is that it goes to MON using the smc > >> #0 call and then changes SPSR so that on return (movs pc) the mode will > >> be different. > > > > Thanks -- yes, that's an exception return so it's the > > expected way to go from Mon to Hyp. > > That was my understanding, yes. Do you still want me to change the > commit message to mention that or will you just do it when applying? I'll add a note when I apply it; thanks. -- PMM | https://lists.gnu.org/archive/html/qemu-arm/2019-01/msg00145.html | CC-MAIN-2019-39 | refinedweb | 272 | 74.73 |
I Need
['1', '2', '3']
[1, 2, 3]
def chain_a_list_int(p_chain :str):
tab_chain=[] # [str]
tab_int=[] # [int] (list to return)
tab_chain = p_chain.split(",")
tab_chain = [int(i) for i in tab_chain]
tab_int.append(tab_chain)
return tab_int
chain_a_list_int(input("enter the number to conserve: "))
<function chain_a_list_int at 0x000000000349FEA0>
print(chaine_a_liste_entier)
tab_int
print(tab_int)
[1, 2, 3]
That's not an error, but an indication that Python doesn't think that you have asked it to call
chain_a_list_int. The minimal tweak to your code is:
the_list = chain_a_list_int(input("enter the number to conserve: ")) print(the_list)
or
print(chain_a_list_int(input("enter the number to conserve: ")))
A reference to the name of the function
chain_a_list_int, without a
( after it, does not actually cause the function's code to run. This distinction will be useful to you later on — for now, make sure any time you type the name of a function, you put a parenthesized expression after that name. (If @ForceBru posts an answer, you'll see a counterexample :) .) | https://codedump.io/share/i0U1gRo08p5W/1/python-list-out-of-function | CC-MAIN-2018-17 | refinedweb | 163 | 64.04 |
In this document
Introduction
This document is for the ASP.NET MVC and Web API. If you're interested in ASP.NET Core, see the ASP.NET Core documentation.
In a web application, exceptions are usually handled in MVC Controller and Web API Controller actions. When an exception occurs, the application user is informed about the error and with an optional reason.
If an error occurs in a regular HTTP request, an error page is shown. If an error occurs in an AJAX request, the server sends the error information to the client and the client then handles and shows it to the user.
Handling exceptions in all web requests is tedious, and hard to keep DRY. ASP.NET Boilerplate automates this. You almost never need to explicitly handle an exception. ASP.NET Boilerplate handles all exceptions, logs them, and returns an appropriate and formatted response to the client. It also handles these responses in the client and shows error messages to the user.
Enabling Error Handling
To enable error handling for ASP.NET MVC Controllers, customErrors mode must be enabled for ASP.NET MVC applications.
<customErrors mode="On" />
It can also be 'RemoteOnly' if you do not want to handle errors on a local computer, for instance. Note that this is only required for ASP.NET MVC Controllers, and not for Web API Controllers.
If you are already handling exceptions in a global filter, it may hide exceptions. Thus, ABP's exception handling may not work as you expected. So if you do this, do it carefully!
Non-Ajax Requests
If a request is not AJAX, an error page is shown.
Showing Exceptions
Imagine that there is an MVC controller action which throws an arbitrary exception:
public ActionResult Index() { throw new Exception("A sample exception message..."); }
Most likely, this exception would be thrown by another method that is called from this action. ASP.NET Boilerplate handles this exception, logs it and shows the 'Error.cshtml' view. You can customize this view to show the error. Here's an example error view (the default Error view in the ASP.NET Boilerplate templates):
ASP.NET Boilerplate hides the details of the exception from users and shows a standard (and localizable) error message, unless you explicitly throw a UserFriendlyException.
UserFriendlyException
The UserFriendlyException is a special type of exception that is directly shown to the user. See the sample code below:
public ActionResult Index() { throw new UserFriendlyException("Ooppps! There is a problem!", "You are trying to see a product that is deleted..."); }
ASP.NET Boilerplate logs it and does not hide the exception:
If you want to show a special error message to users, just throw a UserFriendlyException (or an exception derived from it).
Error Model
ASP.NET Boilerplate passes an ErrorViewModel object as a model to the Error view:
public class ErrorViewModel { public AbpErrorInfo ErrorInfo { get; set; } public Exception Exception { get; set; } }
ErrorInfo contains detailed information about the error that can be shown to the user. The Exception object is the thrown exception. You can check it and show additional information if you want. For example, we can show validation errors if it's an AbpValidationException:
AJAX Requests
If the return type of an MVC action is a JsonResult (or Task<JsonResult for async actions), ASP.NET Boilerplate returns a JSON object to the client when exceptions occur. Sample return object for an error:
{ "targetUrl": null, "result": null, "success": false, "error": { "message": "An internal error occurred during your request!", "details": "..." }, "unAuthorizedRequest": false }
success: false indicates that there is an error. The error object provides the message and details.
When you use ASP.NET Boilerplate's infrastructure to make an AJAX request on the client side, it automatically handles this JSON object and shows an error message to the user using the message API. See the AJAX API documentation for more information.
Exception Event
When ASP.NET Boilerplare handles an exception, it triggers an AbpHandledExceptionData event. ), the HandleEvent method will be called for all exceptions handled by ASP.NET Boilerplate. From there, you can investigate the Exception object in detail. | https://aspnetboilerplate.com/Pages/Documents/Handling-Exceptions | CC-MAIN-2018-43 | refinedweb | 677 | 58.79 |
18 June 2010 17:12 [Source: ICIS news]
By Nigel Davis
LONDON (ICIS news)--Chloralkali producers and, one might expect, their principal customers, take it in their stride - or at least seem to.
The demand pull on the twin products from the electrolysis of brine is very different. If the paper business is buoyant then producers have to hope that the demand pull for chlorine into construction via the polyvinyl chloride chain is healthy, otherwise they could have problems. Prices of chlorine and caustic will reflect activity in very different parts of the economy.
This is because companies look at the output and economics of electrolysis plants in totality. Production economics are based on the electrochemical unit, or ecu, which is the combined value of one tonne of chlorine and 1.1 tonnes of caustic soda.
In a similar position, shouldn’t makers of phenol and acetone work harder at taking a similar approach?
For every one tonne of phenol produced you are left with 0.62 tonnes of acetone. Phenol demand is growing strongly; but that for acetone is not.
The disparity will add colour to acetone in the way it has done in the past and create problems for producers and consumers alike. The way in which prices for the two products are established, will only help exacerbate potential problems.
After a year of difficulty - with end-use demand weak and production issues adding to price volatility in phenol/acetone - the world has turned.
Polycarbonate demand is much stronger, even though consumers buy fewer CDs and DVDs made from polycarbonate than they once did.
Acetone, by contrast, is a much more ‘stable’ product. Some 40% of global output goes into solvents, 24% to make methyl methacrylate, 20% into bisphenol A and 14% into a range of other uses.
Mature and declining end use markets for the chemical will have an impact on the entire phenol chain.
Larger consumers are recycling more acetone. There are new routes to methyl methacrylate that avoid the chemical - one uses ethylene, another, butylenes. Solvent use is mature growing only with the industrial economy.
The ICIS phenol/acetone conference in ?xml:namespace>
Phenol use is expected to expand with increased polycarbonate demand in fast-growing
This is a problem for phenol/acetone producers not simply because of the disparities that will exist when they have excess acetone to sell. It is a difficult problem because while they are able to negotiate acetone prices based on the price of propylene and market conditions their price for phenol is firmly fixed to benzene.
Excess acetone could prove to be a real headache: industry analysts expect there to be a 100,000-200,000 tonne/year global surplus by 2015.
Acetone could be recycled by the producer- back to propylene or to cumeme. It could even find its way into the gasoline pool - although it is said to corrode important engine parts.
A more interesting use would be conversion to isopropanol (IPA), which is widely used as a solvent, an intermediate for paints and inks, and in lacquers, thinners and household products.
IPA is potentially a faster-growing product if you consider solvent use in the growing semiconductor industry in
Of great interest is the price spread between it and acetone of some $300/tonne. The cash cost of making IPA, albeit with a secure source of hydrogen, is between $100 (€81) and $150/tonne.
Adding value down the chain appears to be a real option for phenol/acetone players and a way in which they might be able to gain a little more control over their markets.
An IPA plant fed by acetone was brought on-stream by Novapex in
Delegates in
($1 = €0.81)
For more on phenol | http://www.icis.com/Articles/2010/06/18/9369388/insight-moving-down-the-chain-to-capture-growth-and.html | CC-MAIN-2015-18 | refinedweb | 623 | 61.46 |
Project update — parsing HTML
The last programming language that I learnt before Go was JavaScript and it was 5 years ago. By “learnt” I mean — I created few apps and became really efficient with it. So I must say I fallen out of the loop of continuous technical learning. That’s why learning Go is so painful.
Today I was finally working on something meaty — parsing HTML files brought by HTTP requests — I POST few files and their content is parsed using some XPath. It’s not so far from standard library, but finally it’s something you can’t achieve easily with Go stdlib. I didn’t know that, when I started, but I should have suspected this.
It’s quite easy to parse HTML document to fix its content:
import (
“log”
“strings”
“html”
“bytes”
)
func fixHtml(document string) (string) {
reader := strings.NewReader(document)
root, err := html.Parse(reader)
if err != nil {
log.Fatal(err)
}
var fixingBuffer bytes.Buffer
html.Render(&fixingBuffer, root)
return fixingBuffer.String()
}
It’s not as trivial as it would in Ruby, but I expected this to be more difficult. I won’t explain what’s happening, because it’s quite obvious. Why do we have to “fix” the document? Because XPath library wouldn’t find the node in it.
Ok, now let’s jump to XPath:
func parseHtml(html string) (string) {
reader := strings.NewReader(html)
root, err := xmlpath.ParseHTML(reader)
if err != nil {
log.Fatal(err)
}
xpath := xmlpath.MustCompile(“//table[3]//tr[5]//table//tr”)
value, ok := xpath.String()
if ok {
return value
}
return “”
}
Although it was easy to use XPath it is very limited — e.g. you can’t use `last()` selector and many others. You can iterate to last element using `xmlpath.Iter`, but using XPath would make it more declarative.
What’s interesting in both code samples they are not “object-oriented”, but passing one of arguments as message receiver makes the code feel like it is object-oriented — I really like this feature of Go.
Many things changed since I learnt the JavaScript. Although there was StackOverflow then I barely used it — I was much more keen to just jump into w3schools language reference or API documentation. But using StackOverflow made my learning velocity higher now — I didn’t have to find library, because it was already mentioned in post. I didn’t have to use documentation, because I already had snippets that handled my case. You may laugh at stackoverflow driven development, but there’s no faster way to learn new language, especially when you’re already familiar with some basics. | https://medium.com/jan-filipowski-blog/project-update-parsing-html-1509a7b94581 | CC-MAIN-2018-05 | refinedweb | 432 | 67.35 |
It can be easy to explore data generating mechanisms with the simstudy package
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I learned statistics and probability by simulating data. Sure, I did the occasional proof, but I never believed the results until I saw it in a simulation. I guess I have it backwards, but I that’s just the way I am. And now that I am a so-called professional, I continue to use simulation to understand models, to do sample size estimates and power calculations, and of course to teach. Sure – I’ll use the occasional formula when one exists, but I always feel the need to check it with simulation. It’s just the way I am.
Since I found myself constantly setting up simulations, over time I developed ways to make the process a bit easier. Those processes turned into a package, which I called simstudy, which obviously means simulating study data. The purpose here in this blog entyr is to introduce the basic idea behind simstudy, and provide a relatively brief example that actually comes from a question a user posed about generating correlated longitudinal data.
The basic idea
Simulation using simstudy has two primary steps. First, the user defines the data elements of a data set either in an external csv file or internally through a set of repeated definition statements. Second, the user generates the data, using these definitions. Data generation can be as simple as a cross-sectional design or prospective cohort design, or it can be more involved, extending to allow simulators to generate observed or randomized treatment assignment/exposures, survival data, longitudinal/panel data, multi-level/hierarchical data, datasets with correlated variables based on a specified covariance structure, and to data sets with missing data based on a variety of missingness patterns.
The key to simulating data in simstudy is the creation of series of data defintion tables that look like this:
Here’s the code that is used to generate this definition, which is stored as a data.table :
def <- defData(varname = "nr", dist = "nonrandom", formula = 7, id = "idnum") def <- defData(def, varname = "x1", dist = "uniform", formula = "10;20") def <- defData(def, varname = "y1", formula = "nr + x1 * 2", variance = 8) def <- defData(def, varname = "y2", dist = "poisson", formula = "nr - 0.2 * x1", link = "log") def <- defData(def, varname = "xCat", formula = "0.3;0.2;0.5", dist = "categorical") def <- defData(def, varname = "g1", dist = "gamma", formula = "5+xCat", variance = 1, link = "log") def <- defData(def, varname = "a1", dist = "binary", formula = "-3 + xCat", link = "logit")
To create a simple data set based on these definitions, all one needs to do is execute a single
genData command. In this example, we generate 500 records that are based on the definition in the
deftable:
dt <- genData(500, def) dt ## idnum nr x1 y1 y2 xCat g1 a1 ## 1: 1 7 11.19401 26.92518 100 1 921.48860 0 ## 2: 2 7 11.44471 29.41959 112 1 78.28623 0 ## 3: 3 7 16.69289 44.03212 41 3 2776.72932 1 ## 4: 4 7 11.15279 30.11492 103 2 3408.90636 1 ## 5: 5 7 18.06209 40.93295 19 3 8528.21763 0 ## --- ## 496: 496 7 11.84040 30.91384 101 3 2848.82490 0 ## 497: 497 7 17.82783 36.51813 37 1 1047.21862 1 ## 498: 498 7 16.66917 42.17807 28 2 1219.15208 0 ## 499: 499 7 18.53819 47.81427 25 1 387.60547 0 ## 500: 500 7 12.44773 34.05384 79 3 1692.40276 1
There’s a lot more functionality in the package, and I’ll be writing about that in the future. But here, I just want give a little more introduction by way of an example that came in from around the world a couple of days ago. (I’d say the best thing about building a package is hearing from folks literally all over the world and getting to talk to them about statistics and R. It is really incredible to be able to do that.)
Going a bit further: simulating a prosepctive cohort study with repeated measures
The question was, can we simulate a study with two arms, say a control and treatment, with repeated measures at three time points: baseline, after 1 month, and after 2 months? Of course.
This was what I sent back to my correspondent:
# Define the outcome ydef <- defDataAdd(varname = "Y", dist = "normal", formula = "5 + 2.5*period + 1.5*T + 3.5*period*T", variance = 3) # Generate a 'blank' data.table with 24 observations and assign them to # groups set.seed(1234) indData <- genData(24) indData <- trtAssign(indData, nTrt = 2, balanced = TRUE, grpName = "T") # Create a longitudinal data set of 3 records for each id longData <- addPeriods(indData, nPeriods = 3, idvars = "id") longData <- addColumns(dtDefs = ydef, longData) longData[, `:=`(T, factor(T, labels = c("No", "Yes")))] # Let's look at the data ggplot(data = longData, aes(x = factor(period), y = Y)) + geom_line(aes(color = T, group = id)) + scale_color_manual(values = c("#e38e17", "#8e17e3")) + xlab("Time")
If we generate a data set based on 1,000 indviduals and estimate a linear regression model we see that the parameter estimates are quite good. However, my correspondent wrote back saying she wanted correlated data, which makes sense. We can see from the alpha estimate of approximately 0.02 (at the bottom of the output), we don’t have much correlation:
# Fit a GEE model to the data fit <- geeglm(Y ~ factor(T) + period + factor(T) * period, family = gaussian(link = "identity"), data = longData, id = id, corstr = "exchangeable") summary(fit) ## ## Call: ## geeglm(formula = Y ~ factor(T) + period + factor(T) * period, ## family = gaussian(link = "identity"), data = longData, id = id, ## corstr = "exchangeable") ## ## Coefficients: ## Estimate Std.err Wald Pr(>|W|) ## (Intercept) 4.98268 0.07227 4753.4 <2e-16 *** ## factor(T)Yes 1.48555 0.10059 218.1 <2e-16 *** ## period 2.53946 0.05257 2333.7 <2e-16 *** ## factor(T)Yes:period 3.51294 0.07673 2096.2 <2e-16 *** ## --- ## Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 ## ## Estimated Scale Parameters: ## Estimate Std.err ## (Intercept) 2.952 0.07325 ## ## Correlation: Structure = exchangeable Link = identity ## ## Estimated Correlation Parameters: ## Estimate Std.err ## alpha 0.01737 0.01862 ## Number of clusters: 1000 Maximum cluster size:. | https://www.r-bloggers.com/2017/05/it-can-be-easy-to-explore-data-generating-mechanisms-with-the-simstudy-package-2/ | CC-MAIN-2021-43 | refinedweb | 1,062 | 56.25 |
Atomic core and packages
#21
Posted 15 August 2011 - 09:30 PM
If it has grown too large? Yes, it has, most of users do not know all classes and features it provides.
A core package is good. There are many projects like crawlers or daemons where I don't have any web or something, but I would use the CComponent and like.
PEAR is close to death. It has a complex configuration managed by console commands, and can't live without it due to its complexity. It has a rigid structure as well. Check it to avoid its problems please.
The packages subject is related to the namespaces discussion. Do you plan to separate packages to their own namespaces?
I don't belive a package should have a configuration. Packages are not modules, they are plug-ins that you extract to the source, declare in main.php and use its API in your code.
#22
Posted 01 September 2011 - 06:22 PM
grigori, on 15 August 2011 - 09:30 PM, said:
Agree - a module or component may require configuration, but a package would not.
A package should come with some sort of manifest though, as discussed - this probably shouldn't contain any functional configuration as such, though.
#23
Posted 01 September 2011 - 07:32 PM
I may be missing something on the discussion about configuration, but my two cents:
I believe that every packaged item (extension, module, component etc) should provide its configuration (at least the default one) to be added by the package manager to the application's configuration file(s).
There could be hooks for package installation and uninstallation, too.
Using these hooks, the packaged item will be able to automatically install itself to the filesystem and to the database.
The package metadata (meta file) could have also the version(s) of the framework for wich it is compatible.
#24
Posted 06 September 2011 - 08:28 AM
mentel, on 01 September 2011 - 07:32 PM, said:
If the framework core itself is distributed as a package with a metadata file, like any other package, a package manager would be able to check/update the core itself, the same way any other package is checked/updated.
It would be useful if the package repository provides a compatibility matrix based on feedback from developers, and this should of course take version numbers into account - when package X defines a dependency, it should specify the version number of the dependent package Y it was tested with, but when that dependent package Y receives an upgrade, you don't know for certain if package X is forward compatible with those changes. The package manager can build a compatibility matrix by collecting this information from developers.
Another useful feature would be to provide a release-date in the package metadata - that way, you can put up a candidate release package, for example two weeks before it's official release date. It's a simple communication tool: the vendor has indicated that the release may be superseded by another RC within those two weeks - and the consumer understands that they're using a brand new release which has not yet been widely tested.
One last thought: let's have a web-based package manager interface. Of course, it needs to be accessible from the command-line, for automation purposes, but a web-interface could have a richer user interface - for example, it could collect and display information from the compatibility matrix, render a dependency graph, etc.
#25
Posted 06 September 2011 - 08:37 AM
Might make a useful starting point?
#26
Posted 14 September 2011 - 06:21 AM
- search repo,
- find the package,
- check and display dependencies,
- download package,
- install package
CLI mode or HTTP (GUI) mode?
Perhaps separate module like Gii?
Looks like pretty big thing, uff.
But may bring the framework to completely new level of interaction during development - big step ahead.
Thumb up that you decided to keep modules - they are very powerful and useful.
Lubos
Greatest discoveries in 22nd century will be about the gravitation. | |
#27
Posted 14 September 2011 - 07:24 AM
#28
Posted 10 October 2011 - 03:29 AM
I've a question regarding cli vs. GUI.
As far as I can tell there's currently no other way to run console command from within a web application than exec?!
Do you plan to add a component which works as a link between web app and cli app?
I played around with exec, but the problem is, that you often have different values for yiic on different systems (Win, Mac, Linux).
Best regards,
schmunk
Fork on github
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DevSystem: Mac OS X 10.7 - PHP 5.3 - Apache2 - Yii 1.1 / trunk - Firefox or Safari
#29
Posted 10 October 2011 - 05:26 AM
#30
Posted 14 October 2011 - 08:22 PM
At the moment, Yii flexibility allows to create anything and plug it into the system by just set its alias/pàth and import them automatically when required. Any ideas on how those packages should be coded?
This could be a great feature, but nobody has talked about its format... ideas to work with package manager?
By following a pattern we could ensure the creation of top quality extensions... dont you agree?
#31
Posted 15 October 2011 - 03:08 PM
#32
Posted 15 October 2011 - 05:17 PM
cause it is scary sometimes to use others extensions cause you cant be sure they 100% correct without bugs ...
>)
#33
Posted 17 October 2011 - 04:52 AM
Moreover they should provide a default configuration, often the main application configuration is affected by an extension (such as setting params, loginUrl, etc.). This is another thing to think about ... can we simply merge any package configuration with the application configuration or do we have to implement boundaries?
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DevSystem: Mac OS X 10.7 - PHP 5.3 - Apache2 - Yii 1.1 / trunk - Firefox or Safari
#34
Posted 17 October 2011 - 01:42 PM
Depends on what's inside the package. If it's a module then yes, most of your proposals are looking good but if it's a widget then there's no need to configure anything. I guess we'll just write a guide on extensions to encourage best practice.
#35
Posted 02 November 2011 - 07:39 PM
I would avoid adding complication where it's not necessary, or at least make the default download contain everything.
Never forget the newbies. A seasoned Yii user can trim where necessary.
#36
Posted 06 November 2011 - 02:08 PM
Going further with maven spirit building and installing packages into repository would be also great feature - putting common reusable extensions development into separate projects seems reasonable for large teams.
I also agree with db migrations support on package level. There should be possible adding optional information of migration objects existence, thus installing package can do necessary database schema modifications easily. I can even treat this as "must-have" feature.
#37
Posted 08 November 2011 - 11:16 AM
#38
Posted 08 November 2011 - 04:34 PM
I've checked these about two months ago. Did't like:
1. Lack of simple end user docs.
2. Symfony2 dependencies.
but now, as I can see, everything is in a PHAR and there are some docs. Will check/try it again. Thanks.
#39
Posted 15 December 2011 - 02:08 AM
maybe it is a bit stupid because i do not know many examples you mentioned.. but could the Wordpress plugin system be somehow interesting as a reference?
the idea is that you can download a plugin from the Wordpress site, from the author site or install it directly from Wp admin area + eventually configure it (plugin developers can add an admin page to configure the plugin).
#40
Posted 15 December 2011 - 07:33 AM | http://www.yiiframework.com/forum/index.php/topic/21694-atomic-core-and-packages/page__st__20__p__114821 | CC-MAIN-2014-52 | refinedweb | 1,307 | 62.38 |
NAME | SYNOPSIS | DESCRIPTION | COMMAND FUNCTIONS | SEE ALSO | DIAGNOSTICS
#include <sys/types.h>
#include <sys/conf.h>
#include <sys/sad.h>
#include <sys/stropts.h>
int ioctl(int fildes, int command, int arg);
The STREAMS Administrative Driver provides an interface for applications to perform administrative operations on STREAMS modules and drivers. The interface is provided through ioctl(2) commands. Privileged operations may access the sad driver using /dev/sad/admin. Unprivileged operations may access the sad driver using /dev/sad/user.
The fildes argument is an open file descriptor that refers to the sad driver. The command argument determines the control function to be performed as described below. The arg argument represents additional information that is needed by this command. The type of arg depends upon the command, but it is generally an integer or a pointer to a command-specific data structure.
The autopush facility (see autopush(1M)) allows one to configure a list of modules to be automatically pushed on a stream when a driver is first opened. Autopush is controlled by the following commands:
Allows the administrator to configure the given device's autopush information. arg points to a strapush structure, which contains the following members:
unit_t ap_cmd; major_t sap_major; minor_t sap_minor; minor_t sap_lastminor; unit_t sap_npush; unit_t sap_list [MAXAPUSH] [FMNAMESZ + 1];
The sap_cmd field indicates the type of configuration being done. It may take on one of the following values:
Configure one minor device of a driver.
Configure a range of minor devices of a driver.
Configure all minor devices of a driver.
Undo configuration information for a driver.
The sap_major field is the major device number of the device to be configured. The sap_minor field is the minor device number of the device to be configured. The sap_lastminor field is used only with the SAP_RANGE command, which configures a range of minor devices between sap_minor and sap_lastminor, inclusive. The minor fields have no meaning for the SAP_ALL command. The sap_npush field indicates the number of modules to be automatically pushed when the device is opened. It must be less than or equal to MAXAPUSH , defined in sad.h. It must also be less than or equal to NSTRPUSH, the maximum number of modules that can be pushed on a stream, defined in the kernel master file. The field sap_list is an array of NULL-terminated module names to be pushed in the order in which they appear in the list.
When using the SAP_CLEAR command, the user sets only sap_major and sap_minor. This will undo the configuration information for any of the other commands. If a previous entry was configured as SAP_ALL, sap_minor should be set to zero. If a previous entry was configured as SAP_RANGE , sap_minor should be set to the lowest minor device number in the range configured.
On failure, errno is set to the following value:
arg points outside the allocated address space.
The major device number is invalid, the number of modules is invalid, or the list of module names is invalid.
The major device number does not represent a STREAMS driver.
The major-minor device pair is already configured.
The command is SAP_RANGE and sap_lastminor is not greater than sap_minor, or the command is SAP_CLEAR and sap_minor is not equal to the first minor in the range.
The command is SAP_CLEAR and the device is not configured for autopush.
An internal autopush data structure cannot be allocated.
Allows any user to query the sad driver to get the autopush configuration information for a given device. arg points to a strapush structure as described in the previous command.
The user should set the sap_major and sap_minor fields of the strapush structure to the major and minor device numbers, respectively, of the device in question. On return, the strapush structure will be filled in with the entire information used to configure the device. Unused entries in the module list will be zero-filled.
On failure, errno is set to one of the following values:
arg points outside the allocated address space.
The major device number is invalid.
The major device number does not represent a STREAMS driver.
The device is not configured for autopush.
Allows any user to validate a list of modules (that is, to see if they are installed on the system). arg is a pointer to a str_list structure with the following members:
int sl_nmods; struct str_mlist *sl_modlist;
char l_name[FMNAMESZ+1];
sl_nmods indicates the number of entries the user has allocated in the array and sl_modlist points to the array of module names. The return value is 0 if the list is valid, 1 if the list contains an invalid module name, or -1 on failure. On failure, errno is set to one of the following values:
arg points outside the allocated address space.
The sl_nmods field of the str_list structure is less than or equal to zero.
intro(2), ioctl(2), open(2)
STREAMS Programming Guide
Unless otherwise specified, the return value from ioctl() is 0 upon success and -1 upon failure with
errno set as indicated.
NAME | SYNOPSIS | DESCRIPTION | COMMAND FUNCTIONS | SEE ALSO | DIAGNOSTICS | http://docs.oracle.com/cd/E19683-01/817-0685/6mgfgvah8/index.html | CC-MAIN-2015-48 | refinedweb | 846 | 56.05 |
INET_NET(3) BSD Programmer's Manual INET_NET(3)
inet_net_ntop, inet_net_pton - Internet network number manipulation rou- tines
#include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> char * inet_net_ntop(int af, const void *src, int bits, char *dst, size_t size); int inet_net_pton(int af, const char *src, void *dst, size_t size);
The inet_net_ntop() function converts an Internet network number from network format (usually a struct in_addr or some other binary form, in network byte order) to CIDR presentation format (suitable for external display purposes). bits). in the network address is calculated as the larger of the number of bits in the class to which the address belongs and the number of bits provided rounded up modulo 8. Examples: 10 an 8-bit network number (class A), value 10.0.0.0. 192 a 24-bit network number (class C), value 192.0.0.0. 10.10 a 16-bit network number, value 10.10.0.0. 10.1.2 a 24-bit network number, value 10.1.2.0. 10.1.2.3 a 32-bit network number, value 10.1.2.3. 10.1.2.3/24 a 24-bit network number (explicit), value 10.1.2.3. Note that when the number of bits is specified using "/bits" notation, the value of the address still includes all bits supplied in the external representation, even those bits which are the host part of an Internet address. Also, unlike inet_pton(3) where the external representation is assumed to be a host address, the external representation for inet_net_pton() is assumed to be a network address. Thus "10.1" is as- sumed to be "10.1.0.0" not "10.0.0.1").
byteorder(3), inet(3), inet_pton(3), networks(5)
The inet_net_ntop and inet_net_pton functions first appeared in BIND 4.9.4. MirOS BSD #10-current June. | http://mirbsd.mirsolutions.de/htman/sparc/man3/inet_net_pton.htm | crawl-003 | refinedweb | 307 | 56.76 |
For example the current Hash code is this:
The reason I ask is people in bug reports say, “I’m using 66db43”
Well, how do I know what day that build is?
I tried Googling “Blender Hash” and you can imagine what comes up instead, lol.
For example the current Hash code is this:
The reason I ask is people in bug reports say, “I’m using 66db43”
Well, how do I know what day that build is?
I tried Googling “Blender Hash” and you can imagine what comes up instead, lol.
Used to be on the splash screen, but it doesn’t seem to be there anymore. Now you have to dig into the file folder. If you download as a file (zipped) it should be part of the folder name. Also supposed to be in the “Save system info” text file the program can save using the help menu. Apparently a little bugged on the Ubuntu/Debian edge release at the moment because I’m getting “unknown” for those on my system. Might be working elsewhere though.
I get what you mean though. There really should be a way to have that info copied to the user’s clip board so they can just copy-paste it. Not sure why developers didn’t do that, as I’d think it’d make their work a little easier if they get improved user feedback.
you can use a script to print it!
import bpy,sys
print(‘System info =’,sys.version_info[:])
print (’ Hash =’, bpy.app.build_hash )
happy bl
It’s the final commit before it was built, so if it’s d130c66db43 it’s this one for example: You can see what day it is there. But it’s more useful if something is broken in one version and works in earlier versions.
I presume that the developers are using the git version-control system, which assigns arbitrary “hashes” to uniquely identify each commit. (The full hash is quite long, but is routinely abbreviated.) This would therefore serve, to the developers, as an exact identification of the so-called “commit” that constituted a particular final build-target.
The hash serves only as a unique-identifier and will have no “sequence” at all. (It is so unique that the hashes produced by each developer, working independently of the others, will not collide when their separate streams-of-work (branches) are finally merged. This notion is fundamental to how git works, as a fully-distributed, “server-less” version control system … AFAIK, the only one of its kind.)
The developers will also have some form of build-numbering scheme which they apply, most likely as part of the contnt of each final build-target’s commit. This number is intended for “human purposes,” but could be ambiguous. The hash is not: “in all the world, the hash is absolutely unique and authoritative, but meaningless.”
Okay, thanks everyone.
My original question was which day was which hash built basically.
From the answers the short answer would be:
thanks again | https://blenderartists.org/t/anybody-know-the-sequence-of-hash-versioning-is-determined/700446 | CC-MAIN-2020-40 | refinedweb | 505 | 72.36 |
Opened 7 years ago
Closed 3 years ago
#13803 closed Bug (fixed)
Model attribute cannot be named pk and set primary_key=True
Description (last modified by )
I had an existing database that I wanted to manipulate with Django and ran in through the inspectdb management command. Opening up the admin to try and edit the table led to a consistent Python crash (OS X popped up the crash log which I attached). After trial and error I narrowed it down to the name of the model attribute: "pk". Changing the attribute name to something else and then setting db_column='pk' allowed everything to function normally.
When accessing the model through the shell Python doesn't crash, but no data is returned on queries and nothing can be inserted. Here's an example model that shows the problem, run syncdb to set it up and then try to interact with it.
from django.db import models class Example(models.Model): pk = models.AutoField(primary_key=True, db_column='pk')
---
>> test = Example() File "/Users/jonknee/src/envs/django_1.2/lib/python2.6/site-packages/django/db/models/base.py", line 403, in _set_pk_val return setattr(self, self._meta.pk.attname, value) RuntimeError: maximum recursion depth exceeded while calling a Python object
Changing the attribute name makes everything work normally:
class Example(models.Model): pkey = models.AutoField(primary_key=True, db_column='pk')
This is an issue in both 1.1 and 1.2, I'm using Python 2.6.1.
Attachments (2)
Change History (12)
Changed 7 years ago by
comment:1 follow-up: 2 Changed 7 years ago by
Fixed up formatting. Also this is just going to be a docs issue IMO.
comment:2 follow-up: 3 Changed 7 years ago by
Fixed up formatting. Also this is just going to be a docs issue IMO.
Well, inspectdb could be made smarter and attempt to avoid the problem. #12460 is already open for some improvements along those lines to prevent generation of bad field names. Also if you manually attempt to name a field pk that could get flagged as an error...
comment:3 Changed 7 years ago by
#12460 is already open for some improvements along those lines to prevent generation of bad field names. Also if you manually attempt to name a field pk that could get flagged as an error...
In a related issue, Django doesn't throw up any roadblocks to calling a non primary key field pk which leads to odd behavior (the attribute pk and the actual primary key can't be separately set). Flagging that as an error gets a +1 from me. It's not a good thing when valid Python takes the ship down, doubly so when it's code created by inspectdb and a table cleanly made by syncdb. It took me a long time to figure out because the crashlog had nothing that hinted at what it was.
comment:4 Changed 7 years ago by
Changed 6 years ago by
comment:5 Changed 6 years ago by
I think that this is at least a partial fix. The core should throw an exception when you name a model attribute "pk"
comment:6 Changed 6 years ago by
comment:7 Changed 6 years ago by
This is the wrong place to put the check, since it will only trigger when the table is created by syncdb, which is not a necessary step for using a Django model. It should probably be in django/core/management/validation.py, with tests in modeltests/invalid_models/models.py
Also,
AttributeError would certainly not be the right exception to raise -
By the way, you should not normally set 'Ready for checkin' yourself, but rather get someone else to review your patch and set that.
comment:8 Changed 6 years ago by
comment:9 Changed 6 years ago by
Milestone 1.3 deleted
comment:10 Changed 3 years ago by
Looks like this bug was fixed in ee9fcb1672ddf5910ed8c45c37a00f32ebbe2bb1
Python crash log | https://code.djangoproject.com/ticket/13803 | CC-MAIN-2017-34 | refinedweb | 661 | 62.68 |
sh: -c: line 2: syntax error near unexpected token `;'
sh: -c: line 2: `; } 2>&1'
import os
import commands
import datetime
def cls():
# Define the clear windows command
clear = commands.getoutput('clear')
print clear
cls()
#Read a file
in_file = open("backup_list.txt","r")
list = in_file.read()
in_file.close()
print "list =", list
# Get username and set user variable
user = os.environ['USER']
print "user =", user
# Set backup command
bk_cmd = "tar cvf "
print "bk_cmd =", bk_cmd
# Set path variable
path = "/home/" + user + "/"
print "path =", path
# Set run_bk variable
run_bk = bk_cmd + path + user + ".tar" + " " + list
print "run_bk =", run_bk
# Run backup
output = commands.getoutput(run_bk)
print output
list = /home/tangle/Shared
user = tangle
bk_cmd = tar cvf
path = /home/tangle/
run_bk = tar cvf /home/tangle/tangle.tar /home/tangle/Shared
import os
import commands
import datetime
def cls():
# Define the clear windows command
clear = commands.getoutput('clear')
print clear
cls()
# Print introduction
print "This program will make a backup of a list of files in file_list.txt file."
print
print "Do you want to continue? ",
con = raw_input("[y/n]: ")
if con == "y":
print "Lets get started then"
cls()
print "Where do you want the backup file to be writtten?"
path_name = raw_input("Path to Write to: ")
cls()
print "What would you like to name the backup file?"
bk_name = raw_input("Backup Name: ")
cls()
print "What is the name of the file or directory you would like to backup?"
ob_name = raw_input("Backup Data: ")
cls()
print "Do you want to compress the file? ",
compress = raw_input("[y/n]: ")
bk_cmd = "tar cvf "
bkz_cmd = "tar cvfz "
if compress == "n":
run_bk = bk_cmd + path_name + "/" + bk_name + ".tar" + " " + ob_name
if compress == "y":
run_bk = bkz_cmd + path_name + "/" + bk_name + ".tar.gz" + " " + ob_name
cls()
print "Checking to see if the directory exists."
file_check = os.path.isfile(ob_name)
dir_check = os.path.exists(ob_name)
if file_check == 1:
output = commands.getoutput(run_bk)
print output
cls()
elif dir_check == 1:
output = commands.getoutput(run_bk)
print output
cls()
elif file_check == 0 and dir_check == 0:
cls()
print "ERROR: The object does not exsist!"
print
print
else:
cls()
print "Goodbye"
print
os.system(run_bk) | http://www.linuxquestions.org/questions/programming-9/bash-syntax-when-envoking-tar-command-in-python-script-411455/ | CC-MAIN-2016-44 | refinedweb | 335 | 66.44 |
How to Use Arrays in C Programming
In the real world, information comes individually or in groups. You may find a penny on the road and then a nickel and maybe a quarter! To handle such fortunes in the C language, you need a way to gather variables of a similar type into groups. A row of variables would be nice, as would a queue. The word used in C is array.
How to initialize an array
As with any variable in C, you can initialize an array when it’s declared. The initialization requires a special format, similar to this statement:
int highscore[] = { 750, 699, 675 };
The number in the square brackets isn’t necessary when you initialize an array, as shown in the preceding example. That’s because the compiler is smart enough to count the elements and configure the array automatically.
Exercise 1: Write a program that displays the stock market closing numbers for the past five days. Use an initialized array, marketclose[], to hold the values. The output should look something like this:
Stock Market Close Day 1: 14450.06 Day 2: 14458.62 Day 3: 14539.14 Day 4: 14514.11 Day 5: 14452.06
Exercise 2: Write a program that uses two arrays. The first array is initialized to the values 10, 12, 14, 15, 16, 18, and 20. The second array is the same size but not initialized. In the code, fill the second array with the square root of each of the values from the first array. Display the results.
How to use character arrays (strings)
You can create an array using any of the C language’s standard variable types. A char array, however, is a little different: It’s a string.
As with any array, you can declare a char array initialized or not. The format for an initialized char array can look like this:
char text[] = "A lovely array";
The array size is calculated by the compiler, so you don’t need to set a value in the square brackets. Also — and most importantly — the compiler adds the final character in the string, a null character: \0.
You can also declare the array as you would declare an array of values, though it’s kind of an insane format:
char text[] = { 'A', ' ', 'l', 'o', 'v', 'e', 'l', 'y', ' ', 'a', 'r', 'r', 'a', 'y', '\0' };
Each array element in the preceding line is defined as its own char value, including the \0 character that terminates the string. No, you’ll find the double quote method far more effective at declaring strings.
The code in Displaying a Char Array plods through the char array one character at a time. The index variable is used as, well, the index. The while loop spins until the \0 character at the end of the string is encountered. A final putchar() function (in Line 14) kicks in a newline.
DISPLAYING A CHAR ARRAY
#include <stdio.h> int main() { char sentence[] = "Random text"; int index; index = 0; while(sentence[index] != '\0') { putchar(sentence[index]); index++; } putchar('\n'); return(0); }
Exercise 3: Type the source code from Displaying a Char Array into your editor. Build and run the program.
The while loop in Displaying a Char Array is quite similar to most string display routines found in the C library. These functions probably use pointers instead of arrays. Beyond that bit o’ trivia, you could replace Lines 8 through 14 in the code with the line
puts(sentence);
or even with this one:
printf("%s\n",sentence);
When the char array is used in a function, as shown in the preceding line, the square brackets aren’t necessary. If you include them, the compiler believes that you screwed up. | http://www.dummies.com/how-to/content/how-to-use-arrays-in-c-programming.html | CC-MAIN-2016-22 | refinedweb | 622 | 72.87 |
Now I’ll set up Sanity CMS instead of markdown as a data source for the “
Hello World” in my Gatsby-generated index.html.
<html> <head></head> <body> <div>Hello World</div> </body> </html>
The goal of this tutorial is to make a lovely CMS that looks like this for a content author:
And helps me generates output like this that I can plug into Gatsby:
{ "message":"Hello World", "slug":{ "_type":"slug", "current":"/" }, "template":"xyzzy" }
Prerequisites
- Log into it at
- Install the Node.js JavaScript execution environment (here’s a Windows tutorial), being sure to include the npm package manager, on your computer.
- Make sure that your “path” environment variable for your operating system ends up configured so that when you execute
node -vand
npm -vfrom a command line interface, they both work (that is, you get a message back saying what version of Node or NPM you’re on).
- This is harder than it sounds if you’re new to installing command-line tools on your computer. Be patient.
- Install the Sanity CLI command-line tool using
npm.
- Make sure that your “path” environment variable for your operating system ends up configured so that when you execute
sanity -v, you get a message back saying what version of “
@sanity/cli” you’re on.
- Did it take days to get this to work? Have a cupcake – you’ve earned it! It’ll be easier from here on out.
- Optional: Install a tool on your computer capable of helping you make HTTP requests, such as Postman, Curl, or a general-purpose programming language with a request-making library (such as Python), and learn how to use it to make a basic
GET-typed HTTP request with customized headers.
Navigate the command line to an appropriate folder
I decided I wanted to work out of a folder on my hard drive called
C:\example\mysite_sanity.
Therefore, after I brought up my operating system’s command prompt (I opened it with windows-key ,
cmd, and enter on Windows), I typed the following at the prompt:
cd C:\example\mysite_sanity
Log the Sanity CLI into Sanity.io
Once there, I type the following into my command line:
sanity login
I tap the down arrow on my keyboard until
>to the left of it and hit enter.
Presuming that my computer’s default web browser is already logged into Sanity.io, I will see a confirmation screen in my web browser that I can close. (If I’m not logged in in my web browser, I might have to log into my sanity.io account.)
Initialize a new Sanity project
In my command line, I type:
Once there, I type the following into my command line:
sanity init
I use my keyboard’s up and down arrow keys to highlight
Create new project in turquoise (which also puts a
>to the left of it) and hit enter.
I backspace out the auto-suggested
(My Sanity Project) and instead type a name I like for my project.
I personally decided upon
Gatsby-02.
For demonstration purposes, I overrode the default dataset configuration by typing
n when asked.
Instead, I decided to create a Sanity “dataset” called
top_secret_stuff.
I arrowed up and down until
Private (authenticated requests only) was highlighted turquoise and had a
>to the left of it, then hit enter.
“Hello World” isn’t really going to be a big secret – it’s going right on my web site – but I want to show you how private data sets get used.
Since I had already navigated to
C:\example\mysite_sanity before starting all this, I don’t have to backspace out and re-type the directory that I’d like to put my local “Sanity project” files in – so I just hit enter when Sanity suggests that I install my project there.
We’ll start with as few files as Sanity lets us – I’ll arrow down until I have
Clean project with no predefined schemas selected and hit enter.
This is what Sanity looks like while initializing my project. It takes it a moment, because it’s downloading code from the internet.
Look around the project
Here’s what it looks like in the command line when it’s done:
And here’s what it looks like at when it’s done.
If I run this command, I can see it in the context of other projects I created earlier:
sanity projects list
If I click on my project itself, I’m taken to
- Here, my project ID starts with “z” and ends with “m.”
- I don’t yet have a link next to
studio, which will be my editor – I’ll make one soon enough.
Clicking on the “datasets” tab, I can see
top_secret_stuff.
Clicking on the “settings” tab, I can change this project’s color theme to purple, just for fun.
Add an API key to the project
Clicking the “API” navigation item at left, I’ll find a page where I can click
Add New Token.
Having a token is what will let computer systems read data out of my private dataset.
I’ll call mine
Read-Only Token, set its rights to
Read, and click
Add New Token.
When the token pops up, I have to copy it to my password manager – I can’t get it back.
That said, I can easily delete this token and start over if I fail to copy/paste it properly.
Edit schema files on the hard drive
On my own hard drive at
C:\example\mysite_sanity, I can see that Sanity installed a bunch of files.
Honestly, I only care about the ones in the
schemas folder.
/schemas/schema.js
schema.js in the
schemas folder is the master file defining my Sanity schema.
I’ll use it to tell Sanity about all the other “schema definition” files I create (which in this case, there will be just one of).
It comes like this:
// First, we must import the schema creator import createSchema from 'part:@sanity/base/schema-creator' // Then import schema types from any plugins that might expose them import schemaTypes from 'all:part:@sanity/base/schema-type' //([ /* Your types here! */ ]) })
I update it to say this:
// First, we must import the schema creator import createSchema from 'part:@sanity/base/schema-creator' // Then import schema types from any plugins that might expose them import schemaTypes from 'all:part:@sanity/base/schema-type' // We import object and document schemas import xyzzy from './xyzzy' //([ // The following are document types which will appear // in the studio. xyzzy // When added to this list, object types can be used as // { type: 'typename' } in other document schemas ]) })
/schemas/xyzzy.js
I promised
schema.js an “
xyzzy” schema, so I also added a new file to the
schemas folder and called it
xyzzy.js.
Its contents are as follows:
import icon from 'react-icons/lib/md/note-add' export default { name: 'xyzzy', title: 'X y zz y', type: 'document', icon, fields: [ { name: 'template', title: 'Template', type: 'string' }, { name: 'message', title: 'Message', type: 'string' }, { name: 'slug', title: 'Slug', type: 'slug', description: 'If not happy with what the system generated, you can hand-edit it here' } ], preview: { select: { slug: 'slug', template: 'template', message: 'message' }, prepare(selection) { const {slug, template, message} = selection return { title: `${slug.current} [${template}]`, subtitle: message } } } }
Since I intend to rebuild this Gatsby “Hello World” project using Sanity’s API instead of Markdown files as a data source, I’m sticking with the notion of each data item that needs to become a “page” having
template and
message properties into which I’ll type things like “
xyzzy” and “
(Maybe it’s a little confusing that I decided to name my Sanity object type
xyzzy as well as that being the value I intend to type into
template the first time I use it – sorry.)
Because there won’t be a folder-of-files structure like
/src/pages/ from which Gatsby can infer what page URL I intend to translate a given piece of data into, I’ll also need to hand-type a URL suffix, or “slug.”
fields is where I set all that up.
The
icon bit at the top just makes things pretty in “Sanity Studio,” as does the
preview stuff at the bottom.
How to build files like
xyzzy.js
- See Sanity's official schema documentation.
- Make a 2nd Sanity project on your hard drive where, instead of doing
sanity initwith
Clean project with no predefined schemas, follow these instructions first with one of the sample options like
Movie project,
E-commerce, or
Blog. Try to reverse-engineer what "schema" code seems to correspond to what user experiences you see in Sanity Studio. Personally, I learned a lot from
Movie Project.
Build, deploy, build again, deploy again
To prepare this configuration of Sanity Studio, with my “schema” definitions and all, for deployment to Sanity’s cloud, I run the following command in my command line:
sanity build
Then I run this command:
sanity deploy
The command prompt asks me for a URL prefix at which I’d like to access my “Sanity Studio” for this project.
I chose
gatsby-studio-002.
Then, the command line just sort of … does nothing. For 5 minutes. For me, anyway.
Eventually, refreshing
shows
as my studio URL, but if I try to visit it, I get a “Studio not found” error as JSON-formatted text.
I gave it a couple more minutes, then hit “ Ctrl+Break ” on my keyboard and typed
Y and hit enter to stop this deployment that clearly wasn’t going anywhere.
I ran
sanity build again:
Then ran
sanity deploy again:
And this time, in less than a minute, it worked.
That’s been my approach twice now, so hopefully it works for you if you run into trouble.
Log into Sanity Studio
Now, visiting
from my project dashboard, I’m prompted to log in.
I click
From there, I arrive at
where I see a content type of
X y zz y, just like I defined as the
title property in
xyzzy.js. Neat!
Clicking on
X y zz y, I see a plus sign in the far right and click it.
I’m prompted to type in a
template (I type
xyzzy),
message (I type
Hello World), and
slug (I type
/to indicate that I’d like this content to serve as my web site’s home page).
Note that in the top center of the page, I see “
/ [xyzzy]” in big text and “
Hello World” in small text as a “preview” of this particular item in my data set, based on the way I’d asked for
title (slug followed by the template in square brackets) and
subtitle (message) to be rendered in the
preview I defined in
xyzzy.js.
It’s not a particularly attractive preview of my data, but it got the job done for demonstration purposes.
Test API access
To confirm that my data is really available to the outside world, I fire up Postman.
I set up an HTTP request with a method of
GET, an endpoint of
an
Authorization header that starts with the phrase “
Bearer” and ends with the secret token I saved earlier, and a
Content-Type header of
application/json, then hit Send.
Intro to HTTP (for data folks & managers, especially!)
Katie ・ Jun 3 '19 ・ 10 min read
At bottom, I can see traces of the data I entered in Sanity’s HTTP response body: part of it mentions
Hello World,
xyzzy both as the
template value I typed and, perhaps a bit confusingly – sorry – as the data type of the content itself (as defined in the
name property from
xyzzy.js).
/, and
Set up GraphQL API access
I also want Sanity to make my data available to the outside world in a way that accepts a data-querying language called GraphQL, since that's what a prebuilt plugin for Gatsby relies upon when connecting to Sanity to query my data.
If I build an HTTP request in Postman with a method of
an
Authorization header that starts with the phrase "
Bearer" and ends with the secret token I saved earlier, and a Body in GraphQL syntax with a blank "GraphQL Variables" section but a Query section containing the following code:
{ allXyzzy { message template slug { current } } }
Unfortunately, I get the following HTTP response body from Sanity:
{ "statusCode": 404 "error": "Not Found", "message": "GraphQL schema not found for dataset/tag" }
Bummer.
It turns out that I have to explicitly tell Sanity that I'd like to enable GraphQL-based queries.
I do this by typing the following command into my computer's command prompt:
sanity graphql deploy --playground
Now when I re-run the same HTTP request that just failed on me, I get the following response body:
{ "data": { "allXyzzy": [ { "message": "Hello World", "template": "xyzzy", "slug": { "current": "/" } } ] } }
Much better!
If you're not used to writing GraphQL queries (I'm certainly not), visit
replacing
your-project-id and
your-dataset-name, of course, in a web browser while logged into Sanity.
That's the "playground" you set up by adding the
--playground flag to your Sanity CLI command deploying a graphql interface for your dataset.
It comes with an editor and a big "run button" where you can make all the typos you want as you learn GraphQL. It also gives you some hints while you type.
Next steps
Stay tuned – next I’ll set up a Gatsby site that not only displays my “Hello World” on the home page, but has a “live preview” that changes as people edit the value of
message in Sanity Studio.
Posts in this series
- Part 1 - Gatsby Minimum Viable Build
- Part 2 - Gatsby React Minimum Viable Markdown Template / Component
- Part 3 - Gatsby React WSYIWYG CMS-Friendly Markdown
- Part 4 - Why WYSIWYG static site CMS's love Gatsby
- Part 5 - This Article
Discussion (0) | https://dev.to/katiekodes/sanity-cms-minimum-viable-build-4j7 | CC-MAIN-2022-21 | refinedweb | 2,314 | 63.12 |
It is time to unmask the computing community as a Secret Society for the Creation and Preservation of Artificial Complexity. ~ Edsger W. Dijkstra
Cixl shares many ideas with C, Forth and Common Lisp; as well as the hacker mindset that unites them. The language is implemented as a straight forward VM-based interpreter that is designed to be as fast as possible without compromising on simplicity and flexibility; combined with a code generator for compiling native executables. The codebase has no external dependencies and is currently hovering around 15 kloc including tests and standard library.
Examples should work in the most recent version and run clean in
valgrind. The first version of the language is more or less feature complete; current work is focused on cleaning up the code, dotting i's and crossing t's.
You may try Cixl online here, and a Linux/64 binary may be found over there. To build Cixl yourself, you'll need a reasonably modern GCC and CMake installed. Building on macOS unfortunately doesn't work because of lacking POSIX support. A basic REPL is included, it's highly recommended to run it through
rlwrap for a less nerve wrecking experience.
$ git clone $ cd cixl $ mkdir build $ cd build $ cmake .. $ sudo make install $ sudo ldconfig /usr/local/lib $ rlwrap cixl Cixl v0.9.8, 18044/21268 bmips Press Return twice to evaluate. 1 2 + ... [3] quit $
Besides the document you're reading right now, more detailed articles on specific features and design considerations that went into them may be found here; and a growing library of real worldish examples here.
Contrary to the current trend of stacking abstractions in the name of portability, Cixl embraces the chosen requirement and limitation of running on top of a reasonably POSIX compliant Unix derivative; by integrating deep into the C tool chain, and by providing features optimized for Unix feature set.
Cixl doesn't use a garbage collector, which leads to more predictable performance and resource usage. Values are either automatically copied or reference counted, and references are decremented instantly as values are popped from the stack and variables go out of scope.
Are you quite sure that all those bells and whistles, all those wonderful facilities of your so called powerful programming languages, belong to the solution set rather than the problem set? Edsger W. Dijkstra
Cixl expects arguments before operations and provides direct access to the parameter stack. Basic stack operations have dedicated operators;
% for copying the last value,
_ for dropping it,
~ for swapping the last two values and
| for clearing the stack.
.. pushes all items in the specified sequence.
| 1 2 3 % [1 2 3 3] _ [1 2 3] ~ [1 3 2] | [] [1 2 3] [[1 2 3]] .. [1 2 3]
When launched with arguments; Cixl interprets the first argument as filename to load code from, and pushes remaining on
#args.
test.cx
#!/usr/local/bin/cixl use: (cx/stack %) (cx/str upper) (cx/io say); #args pop % upper say
$ ./cixl test.cx foo FOO $ sudo cp ./cixl /usr/local/bin $ chmod +x test.cx $ ./test.cx foo FOO
Executing
cixl -e compiles the specified file to a statically linked executable. Flags following the filename are passed straight to
gcc. When running the executable, all arguments are pushed on
#args.
$ cixl -e cixl/examples/guess.cx -o guess $ ls -all guess -rwxrwxr-x 1 a a 941856 Feb 17 18:53 guess $ ./guess Your guess: 50 Too high! Your guess: 25 Too low! Your guess: $
Code may be loaded from external files using
load. The loaded code is evaluated in the current scope by default.
test.cx:
2 +
| 1 'test.cx' load [3]
External files may alternatively be included in the current compilation unit using
include:.
test1.cx:
2 +
test2.cx:
1 include: 'test1.cx'
The entire language is split into libraries to enable building custom languages on top of sub sets of existing functionality.
use: cx; may be used as a short cut to import everything. The REPL starts with everything imported while the interpreter and compiler starts with nothing but
include:,
lib: and
use:. The following standard libraries are available:
The default library is called the
lobby.
| this-lib [Lib(lobby)] id [`lobby] get-lib [Lib(lobby)]
All types and functions belong to a library,
lib may be used to find out which.
| Int lib [Lib(cx/abc)] | &= [Func(=)] lib [Lib(cx/cond)] | &=<Rec Rec> [Fimp(= Rec Rec)] lib [Lib(cx/rec)]
Cixl is statically and strongly typed; but since it's approach to typing is gradual, it allows you to be exactly as precise as you feel like. All types have capitalized names, the following are defined out of the box:Type Parents Lib A Opt cx/abc Bin A cx/bin Buf A cx/io/buf Bool A cx/abc Cmp A cx/abc File Cmp cx/io Fimp Seq cx/abc Float Num cx/abc Func Seq cx/abc Int Num Seq cx/abc Iter Seq cx/abc Lambda Seq cx/abc Nil Opt cx/abc Num Cmp cx/abc Opt cx/abc Pair Cmp cx/pair Poll A cx/io/poll Proc Cmp cx/proc Rec Cmp cx/rec Ref A cx/ref RFile File cx/io RGB A cx/gfx RWFile RFile WFile cx/io Seq A cx/abc Stack Cmp Seq cx/abc Str Cmp Seq cx/abc Sym A cx/abc Table Seq cx/table TCPClient RWFile cx/net TCPServer RFile cx/net Time Cmp cx/time Type A cx/abc WFile File cx/io
| 42 type [Int] | type [Type<Int>] | Int A is [#t] | 42 Str is [#f]
New type ids may be defined for existing types using
type-id::
type-id: Pos Pair<Int Int>; 1 2, Pos is [#t]
The id may optionally be parameterized and/or refer to one of several different types. A list of constraints may be specified after the id, it serves as documentation that is checked against all specified members and is used to determine compatibility for the generated type.
type-id: StackIter<A>(Seq<Arg0>) Stack<Arg0> Iter<Arg0>; [1 2 3] StackIter<Int> is 'foo' iter StackIter<Char> is 42 StackIter is [#t #t #f]
Type safe wrappers for existing types may be created using
type:, functions for wrapping/unwrapping are automatically created:
type: IntStr Int Str; 42 int-str type 'foo' int-str str [IntStr<Int> 'foo']
Variables may be bound in the current scope using the
let: macro.
| let: foo 'bar'; $foo ['bar'] | let: foo 'baz'; Error in row 1, col 10: Attempt to rebind variable: 'foo' []
Multiple names may be bound at the same time by enclosing them in parens.
| let: (x y z) 1 2 3 4 +; $x $y $z [1 2 7]
Types may be specified for documentation and type checking.
| let: (x y Int z Str) 1 2 3; Error in row 1, col 5: Expected type Str, actual: Int [1 2]
Since
let: doesn't introduce its own scope, values already on the stack may be bound using the same construct.
| 1 2 3 let: (x y z); $z $y $x [3 2 1]
The same functionality may be accessed symbolically.
| `foo var [#nil] | `foo 42 let `foo var [42]
Constants may be bound using the
define: macro. They behave much like variables; but live in a separate, library global namespace prefixed by
# rather than
$; and are bound at compile time rather than evaluation.
func: launch-rockets()(_ Int) 'Launching rockets!' say 42; | define: (nrockets Int) launch-rockets; Launching rockets! [] #nrockets [42]
Two flavors of equality are provided.
Value equality:
| [1 2 3] [1 2 3] = [#t]
And identity:
| 'foo' 'foo' == [#f] | 42 42 == [#t]
Symbols are immutable singleton strings that support fast equality checks.
| `foo [`foo] = `foo [#t] | `foo `bar = [#f] | 'baz' sym [`baz] str ['baz']
Unique symbols may be generated by calling
new.
| Sym % new ~ new [`s7 `s8]
Some values are reference counted; strings, stacks, lambdas etc. Reference counted values display the number of references following
r when printed. Doubling the copy operator results in a deep copy where applicable and defaults to regular copy where not.
| [1 2 3] % [[1 2 3] [1 2 3]] | [1 2 3] %% [[1 2 3] [1 2 3]]
References may be created manually, which enables using reference semantics for value types.
| let: r #nil ref; $r [Ref(#nil)] 42 set $r [Ref(42)] deref [42]
Code enclosed in parens is evaluated in a separate scope, remaining values on the stack are returned on scope exit.
| 1 (2 3 stash 4) [1 [2 3] 4]
Variables in the parent scope may be referenced from within, but variables defined inside are not visible from the outside.
| let: foo 1; (let: foo 2; $foo) $foo [2 1]
Strings are null terminated, reference counted sequences of characters.
| 'foo' stack [[@f @o @o]]
Strings may alternatively be iterated by line,
| 'foo@nbar@r@nbaz' lines stack [['foo' 'bar' 'baz']]
or by word.
| 'foo,bar-baz!?' words stack [['foo' 'bar-baz']]
Subtracting strings returns the edit distance.
| 'fooxxxbar' 'foobar' - [3]
Characters are single bytes, a separate unicode type might be added eventually. Literals are preceded by
@, or
@@ for non-printable characters outside of strings.
| 'foo@010bar@nbaz' ['foo bar baz'] 3 get [@@n]
say and
ask may be used to perform basic terminal IO.
| 'Hello' say 'What@'s your name? ' ask Hello What's your name? Sifoo ['Sifoo']
Most values support being written to files and read back in. Calling
write on a value will write it's serialized representation to the specified stream.
| now [Time(2018/0/12 1:25:12.123436182)] #out ~ write [2018 0 12 1 25 12 123436182] time []
While calling
read will parse and evaluate one value at a time from the specified stream.
| #in read [Iter(0x5475950)] next [2018 0 12 1 25 12 123436182] time [Time(2018/0/12 1:25:12.123436182)]
Files may be opened for reading/writing by calling
fopen, the type of the returned file depends on the specified mode. Valid modes are the same as in C, r/w/a(+). Files are closed automatically when the last reference is dropped.
let: f 'test.out' `w fopen; $f [RWFile(0x5361130)] now write []
Any value may be printed to a
WFile using
['foo' 42 @@n] $f print []
Files iterate characters by default, which means that string sequence functions may be used directly.
test.txt
foo, bar baz
let: f 'test.txt' `r fopen; | $f str ['foo, bar baz '] let: f 'test.txt' `r fopen; | $f words stack [['foo' 'bar' 'baz']]
Two kinds of code comments are supported, line comments and block comments.
| 1 // Line comments terminate on line breaks + 2 [3] | 1 /* While block comments may span multiple lines */ + 2 [3]
Besides optionals, Cixl provides basic exceptions. Two functions are provided for signalling errors.
throw may be used to throw any value as an error.
| 'Going down!' throw Error in row 1, col 6: Going down! []
While
check may be used to throw an error when the specified condition doesn't hold.
| 1 2 = check Error in row 1, col 7: Check failed []
Thrown values may be caught using
catch:, the first matching clause is evaluated with the error pushed on stack.
| 42 throw catch: (Int `int) (A `a); ~, [`int Error(42),] y value [42]
Catching
_ executes the specified actions regardless of any errors.
| catch: _ 'Cleaning up...' say; Cleaning up... []
Putting braces around a block of code defines a lambda that is pushed on the stack.
| {1 2 3} [Lambda(0x52d97d0)] call [1 2 3]
Lambdas inherit the defining scope.
| (let: x 42; {$x}) call [42]
Any value may be treated as a boolean; some are always true; integers test true for anything but zero; empty strings test false etc. The
? operator may be used to transform any value to its boolean representation.
| 0? [#f]
While the
! operator negates any value.
| 42! [#f]
if,
else and
if-else may be used to branch on a condition, they call '?' implicitly so you can throw any value at them.
| 'foo' %% &upper if ['FOO'] | #nil { say 'not true' } else not true [] | 42 `not-zero `zero if-else [`not zero]
Values may be chained using
and /
or.
| #t 42 and [42] | 0 42 and [0] | 42 #t or [42] | 0 42 or [42]
Lambdas may be used to to prevent evaluating unused arguments when chaining.
| 42 {say 'Bummer!' #t} or [42]
The
switch: macro may be used to untangle chains of if/-else calls. The first clause which condition returns a value that's conditionally
#t is executed.
((let: n 100 rand ++; { 'Your guess: ' ask % { let: c int $n <=>; switch: (($c `< =) 'Too low!' say #t) (($c `> =) 'Too high!' say #t) (#t 'Correct!' say #nil); } { _ #nil } if-else }) &_ for)
|'examples/guess.cx' load Your guess: 50 Too high! Your guess: 25 Too low! Your guess: 37 Too low! Your guess: 43 Correct!
The
func: macro may be used to define named functions. Several implementations may be defined with the same name as long as they also have the same arity and different argument types. Functions capture their defining environment and open an implicit child scope on evaluation. Function definitions are allowed anywhere, but are processed in order of appearance during compilation.
Functions are required to specify their arguments and results.
func: say-hi(n)() ['Hi ' $n @!] say; | 'stranger' say-hi Hi stranger! []
Function arguments and results may optionally be anonymous and/or typed.
_ may be used in place of a name for anonymous arguments and results.
A may be used to match any type and is used as default when no type is specified.
func: any-add(x y)(_ A) $x $y +; | 7 35 any-add [42]
Previous argument types may be referenced by index, it is substituted for the actual type on evaluation.
func: same-add(x Num y Arg0)(_ Arg0) $x $y +; | 7 34 same-add [42] | 7 'foo' same-add Error in row 1, col 7: Func not applicable: same-add [7 'foo']
Literal values may used instead of types. Anonymous arguments are pushed on the function stack before evaluation.
func: is-fortytwo(_ Int)(#f) _; func: is-fortytwo(42)(#t); | 41 is-fortytwo [#f] | 42 is-fortytwo [#t]
Functions may return multiple results.
func: flip(x y Opt)(_ Arg1 _ Arg0) $y $x; 1 2 flip [2 1]
Overriding existing implementations is as easy as defining a function with the same arguments.
func: +(x y Int)(_ Int) 42; | 1 2 + [42]
recall may be used to call the current function recursively in the same scope. The call may be placed anywhere, but doesn't take place until execution reaches the end of the function.
func: fib-rec(a b n Int)(_ Int) $n? {$b $a $b + $n -- recall} $a if-else; func: fib(n Int)(_ Int) 0 1 $n fib-rec; | 50 fib [12586269025]
Argument types may be specified in angle brackets to select a specific function implementation. Besides documentation and type checking, this allows disambiguating calls and helps the compiler inline in cases where more than one implementation share the same name.
| &+<Int Int> [Fimp(+ Int Int)] | &+<Str Str> Error in row 1, col 4: Fimp not found: +<Str Str> [] | 7 35 +<Int Int> [42]
A stack containing all implementations for a specific function may be retrieved by calling the
imps function.
| &+ imps [[Fimp(+ Float Float) Fimp(+ Int Int)]]
Prefixing a function name with
& pushes a reference on the stack.
| 35 7 &+ [35 7 Func(+)] call [42]
Where conversions to other types make sense, a function named after the target type is provided.
| '42' int [42] str ['42'] 1 get [@2] int [50] 5 + char [@7]
The
#nil value may be used to represent missing values. Since
Nil isn't derived from
A, stray
#nil values never get far before being trapped in a function call;
Opt may be used instead where
#nil is allowed.
func: foo(x A)(); func: bar(x Opt)(_ Int) 42; | #nil foo Error in row 1, col 1: Func not applicable: foo [#nil] | #nil bar [42]
Stacks are one dimensional dynamic arrays that supports efficient pushing, popping and random access.
| [1 2 3 4 +] [[1 2 7]] % 5 push [[1 2 7 5]] % pop [[1 2 7] 5] _ {2 *} for [2 4 14]
Stacks may be sorted in place by calling
sort.
| [3 2 1] % #nil sort [[1 2 3]] | [1 2 3] % {~ <=>} sort [[3 2 1]]
Values may be paired by calling
,. Pairs provide reference semantics and access to parts using
a and
b.
| 1 2, [1 2,] % a ~ b [1 2]
Tables may be used to map
Cmp keys to values, entries are ordered by key.
let: t new Table; $t 2 'bar' put $t 1 'foo' put $t [Table(1 'foo', 2 'bar')] stack [[1 'foo', 2 'bar',]] | $t 1 'baz' put $t 2 delete $t [Table((1 'baz'))]
The
times function may be used to repeat an action N times.
| 10 42 times [42 42 42 42 42 42 42 42 42 42]
| 0 42 &++ times [42]
While
for repeats an action once for each value in any sequence.
| 10 {42 +} for [42 43 44 45 46 47 48 49 50 51]
| 'foo' &upper for [@F @O @O]
Sequences support mapping actions over their values,
map returns an iterator that may be chained further or consumed.
| 'foo' {int ++ char} map [Iter(0x545db40)] #nil join ['gpp']
Sequences may alternatively be filtered, which also results in a new iterator.
| 10 {5 >} filter [Iter<Int>(0x54dfd80)] {} for [6 7 8 9]
Iterators may be created manually by calling
iter on any sequence and consumed manually using
next and
drop.
| [1 2 3] iter [Iter(0x53ec8c0)] % % 2 drop next ~ next [3 #nil]
Functions and lambdas are sequences, calling
iter creates an iterator that keeps returning values until the target returns
#nil.
func: forever(n Int)(_ Lambda) {$n}; | 42 forever iter % next ~ next [42 42]
Cixl provides a single concept to represent points in time and intervals. Internally; time is represented as an absolute, zero-based number of months and nanoseconds. The representation is key to providing dual semantics, since it allows remembering enough information to give sensible answers.
Times may be queried for absolute and relative field values;
| let: t now; $t [Time(2018-00-03 20:14:48.105655092)] % date ~ time [Time(2018-00-03) Time(20:14:48.105655092)] | $t year $t month $t day [2018 0 3] | $t months [24216] 12 / int [2018] | $t hour $t minute $t second $t nsecond [20 14 48 105655092] | $t h $t m $t s $, ms $t us $t ns [93 5591 335485 335485094 335485094756 335485094756404] | $t h 24 / int [3] | $t m 60 / int [93]
manually constructed;
| [2018 0 3 20 14] time [Time(2018-00-03 20:14:0.0)] | 3 days [Time(72:0:0.0)] days [3]
compared, added and subtracted;
| 2m 120s = [#t] | 1 years 2 months + 3 days + 12h - [Time(0001-02-02) 12:0:0.0] now <= [#t] | 10 days 1 years - [Time(-1/0/10)] days [-356]
and scaled.
| 1 months 1 days + 3 * [Time(0/3/3)]
Records map finite sets of typed fields to values. Record definitions are allowed anywhere, but are processed in order of appearance during compilation.
new may be used to create new record instances. Getting and putting field values is accomplished using symbols, uninitialized fields return
#nil.
rec: Node<A> left right Node value Arg0; | let: n Node<Int> new; $n `value 42 put $n [Node<Int>(0x12ffb28)] `value get [42] | $n `left get [#nil]
Record types may specify a list of parent types, duplicate fields are not allowed.
rec: Foo x Int; rec: Bar(Foo) y Str; | Bar new % `x 42 put % `y 'abc' put [Bar(0xb289f8)]
Records provide full deep equality by default, but
= may be implemented to customize the behavior.
rec: Foo x Int y Str; | let: (bar baz) Foo new %%; $bar `x 42 put $bar `y 'bar' put $baz `x 42 put $baz `y 'baz' put $bar $baz = [#f] func: =(a b Foo)(_ Bool) $a `x get $b `x get =; | $bar $baz = [#t]
Besides IO polling with callbacks, Cixl supports two more flavors of cooperative concurrency; tasks and coroutines.
Tasks allow running multiple cooperative threads of execution in parallel.
let: s Sched new; let: out []; $s { $out 1 push resched $out 2 push } push $s { $out 3 push } push $s run $out @, join say 1, 3, 2
Coroutines allow suspending, resuming and restarting the execution of a call.
let: c {1 suspend 3 suspend 5} coro; | $c call $c call $c call [1 3 5] | $c call Error in row 1, col 3: Coro is done | $c reset $c call $c call [1 3]
Coroutines may alternatively be iterated.
let: c {1 suspend 3 suspend 5} coro; [$c {2 *} for] [2 6 10]
A
Bin represents a block of compiled code. The compiler may be invoked from within the language through the
compile function. Binaries may be passed around and called, which simply executes the compiled operations in the current scope.
| Bin new % '1 2 +' compile call [3]
Type checking may be partly disabled for the current scope by calling
unsafe, which allows code to run slightly faster. New scopes inherit their safety level from the parent scope. Calling
safe enables all type checks for the current scope.
| {10000 {50 fib _} times} clock 1000000 / int [317] | unsafe {10000 {50 fib _} times} clock 1000000 / int [282]
There is still plenty of work remaining in the profiling and benchmarking department, but preliminary indications puts compiled Cixl at slightly faster to twice as slow as Python3. Measured time is displayed in milliseconds.
We'll start with a tail-recursive fibonacci to exercise the interpreter loop:
use: cx; func: fib-rec(a b n Int)(_ Int) $n?<Opt> {$b $a $b +<Int Int> $n -- recall} $a if-else; func: fib(n Int)(_ Int) 0 1 $n fib-rec; {10000 {50 fib _} times} clock 1000000 / int say $ cixl -e cixl/perf/bench1.cx -o bench1 $ ./bench1 192
from timeit import timeit def _fib(a, b, n): return _fib(b, a+b, n-1) if n > 0 else a def fib(n): return _fib(0, 1, n) def test(): for i in range(10000): fib(50) print(int(timeit(test, number=1) * 1000)) $ python3 cixl/perf/bench1.py 118
Next up is consing a stack:
use: cx; {let: v []; 10000000 {$v ~ push} for} clock 1000000 / int say $ cixl -e cixl/perf/bench2.cx -o bench2 $ ./bench2 1184
from timeit import timeit def test(): v = [] for i in range(10000000): v.append(i) print(int(timeit(test, number=1) * 1000)) $ python3 cixl/perf/bench2.py 1348
Moving on to instantiating records:
use: cx; rec: Foo x Int y Str; {10000000 {Foo new % `x 42 put<Rec Sym A> `y 'bar' put<Rec Sym A>} times} clock 1000000 / int say $ cixl -e cixl/perf/bench3.cx -o bench3 $ ./bench3 3207
from timeit import timeit class Foo(): pass def test(): for i in range(10000000): foo = Foo() foo.x = 42 foo.y = "bar" print(int(timeit(test, number=1) * 1000)) $ python3 cixl/perf/bench3.py 3213
And last but not least, exception handling:
use: cx; {10000000 { `error throw 'skipped' say catch: A _;} times} clock 1000000 / int say $ ./cixl ../perf/bench4.cx 4771 $ cixl -e cixl/perf/bench4.cx -o bench4 $ ./bench4 3531
from timeit import timeit def test(): for i in range(10000000): try: raise Exception('error') print('skipped') except Exception as e: pass print(int(timeit(test, number=1) * 1000)) $ python3 cixl/perf/bench3.py 3813
Give me a yell if something is unclear, wrong or missing. And please consider helping out with a donation via paypal or liberapay if you find this worthwhile, every contribution counts.
Continue reading on github.com | https://hackerfall.com/story/show-hn-cixl-a-minimal-decently-typed-scripting-l | CC-MAIN-2019-51 | refinedweb | 3,976 | 69.72 |
sequence<byte> ByteSeq;
interface Transceiver {
ByteSeq get();
void put(ByteSeq bs);
};
void getDesktpImage(std::vector<BYTE>& imgBuf)
{
captuer the desktop image into a buffer[n] //use freeImage library
imgBuf.reserve(n);
imgBuf.resize(n);
memcpy(&imgBuf[0], buffer, n);
}
vector result(buffer, buffer + n);
imgBuf.swap(result);
interface ImageGetter
{
["amd"] void getImageData(["cpp:range"] out ByteSeq data);
};
void
ImageGetter::getImageData_async(const AMD_ImageGetter_getImageDataPt& cb, const Ice::Current& current)
{
// read n bytes of data into buffer.
cb->ice_response(pair<const Ice::Byte*, const Ice::Byte*>(buffer, buffer + n));
}
matthew wrote:
Note that vector guarantees that all data is kept in one contiguous segment so you don't need to do the copy one step a time, and on the client side you don't need to copy at all.
Slice byte is an 8-bit byte that is guaranteed not to be tampered with in transit, so it is suitable for sending binary.
Cheers,
Michi.
It equals to 1MB and can be changed to some extent via Ice.MessageSizeMax property.
To transfer really big amount of binary data (e.g. 1GB) you have to invoke the put() method several times.
The transfer of files with data is rather typical task and maybe Ice can provide more help,
e.g. by extending the Slice language with new built-in type 'File' :
interface Transceiver {
File get();
void put(File bs);
};
The semantic of File can be similar to 'sequence<byte>' but implementation can be done via memory mapping ('mmap').
Of course, this approach immediatly rises another question: binary vs text files.
--
Cheers, Nikolai
Transfering binary data with sequence would be in bad performance, is it?
If not, how does ICE solve the issue?
If you are concerned about the overhead for using an std::vector<Ice::Byte>, this really only matters if you have a slow computer with a very fast (gigabit) network. Otherwise the network is the limiting factor, not Ice or std::vector.
if put Ice::byte to std::vector,the vector will use more memory than our data. We can make a bigger data block,put it into vector.
#ifndef _ICE_BINBLOCK_ICE
#define _ICE_BINBLOCK_ICE
module Trans
{
struct BinBlock
{
byte b0;
byte b1;
byte b2;
byte b3;
byte b4;
byte b5;
byte b6;
byte b7;
byte b8;
byte b9;
byte b10;
byte b11;
byte b12;
byte b13;
byte b14;
byte b15;
byte b16;
byte b17;
byte b18;
byte b19;
byte b20;
byte b21;
byte b22;
byte b23;
byte b24;
byte b25;
byte b26;
byte b27;
byte b28;
byte b29;
byte b30;
byte b31;
};
sequence<BinBlock> BinBlockList;
struct BinData
{
BinBlockList datalist;
int size;
};
interface Transceiver {
BinData get();
void put(BinData data);
};
};
#endif _ICE_BINBLOCK_ICE
ICE set up many constrains to programmer to keep things simple, that's always OK. But this time, I think this design is bad.
I developed a applications just like TightVNC, the server can transfer desktop image as JPEG fromat to the client. I encode the image data push_back to a std::vector byte by byte in server side, and decode it to image binary data byte by byte too. When the applications is working, they are not real-time, but feel time delay distinctly.
Can you leave me a interface to transfer binary data as fast as possible?
Also, before we offer you further assistance you must fill in your signature information as detailed in the link contained in my signature.
Server side:
void getDesktpImage(std::vector<BYTE>& imgBuf)
{
captuer the desktop image into a buffer[n] //use freeImage library
imgBuf.reserve(n);
int i=0;
for(i=0; i<n; ++i)
{
imgBuf.push_back(buffer);
}
}
Client side:
std::vector<BYTE> imgBuf;
obj->getDesktpImage(imgBuf);
int i=0;
int n=imgBuf.size();
BYTE* pBuf=new BYTE[n];
for(i=0; i<n; ++i)
{
pBuf=imgBuf);
}
use pBuf to display the remote desktop image
delete []pBuf;
PS.
What are the zero-copy methods?
You could do something more like:
You can make this a little more efficient because this avoids the initial fill of the vector with zeros.
The best solution here is to use AMD and the cpp:range mapping which avoids the additional copy altogether. Something like:
You an look at the IcePatch2 source for a full example (grep for getFileCompressed_async).
Note that as the initial article said you probably don't want to send the entire vector all at once either -- assuming the images are big.
I doubt that Ice has anything to do with your performance problems. A straight copy for all but the most performance and memory intensive applications is no problem -- if your application is implemented correctly. I suggest the use of a good profiler to help isolate the trouble spots.
You can read up on the zero-copy in the Ice manual, or you can look at my latest article in Connections for an example.
I don not know that "vector guarantees that all data is kept in one contiguous segment" at all!
I think my problem has been solved.
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Loops
The other main type of control statement is the loop. Loops allow a statement, or block of statements, to be repeated. Computers are very good at repeating simple tasks many times. The loop is C's way of achieving this.
C gives you a choice of three types of loop, while, do-while and for.
The while Loop
The is not null, the index is incremented and the test is repeated. We’ll go in depth of arrays later. Let us see an example for while loop:
#include <stdio.h>
int main()
{
int count;
count = 0;
while (count < 6)
{
printf("The value of count is %d\n", count);
count = count + 1;
}
return 0;
}
and the result is displayed as follows:
The value of count is 0
The value of count is 1
The value of count is 2
The value of count is 3
The value of count is 4
The value of count is | https://www.datadoctor.biz/data_recovery_programming_book_chapter5-page21.html | CC-MAIN-2019-22 | refinedweb | 175 | 77.77 |
This. Unfortunately, despite its dependence on computers to operate at all, most of the information is only understandable by humans and not by computers. While computers can use the syntax of HTML documents to display them to you in a browser, Web computers can't understand the content—the semantics.
The Semantic Web is Tim Berners-Lee's vision of the future of the Web. Although the dream is not yet realized, enough building blocks are now in place to enable you to take advantage of several Semantic Web technologies on your Web site, including RDF, OWL and SPARQL. The goal of the Semantic Web is to expose the vast information resource of the Web as data that computers can automatically interpret.
The Web was originally all about documents. The simple act of clicking on a link in your Web browser triggers your browser to ask a Web server to send you a document, which it then displays to you. The document might be your calendar for the next seven days, or it might be an e-mail from a friend. The Web browser doesn't really care; it just follows its internal rules for displaying the page. It's up to you to understand the information on the page.
Structuring data adds value to that data. With consistent structure, it can be used in more ways. You can see the demand for structured data today in the proliferation of APIs that have sprung up around Web sites as a part of the Web 2.0 trend—an API is structured data, and structured data from a variety of sources is what powers mashups. The idea behind mashups is that data is pulled from various sources on the Web and, when combined and displayed in a unified manner, this combination of elements adds value over and above the source information alone.
The individual APIs that everyone is busy building are to solve the exact same problem that the Semantic Web is intended to address: Expose the content of the Web as data and then combine disparate data sources in different ways to build new value. Rather than build and maintain your own API, you can build your Web site to take full advantage of the Semantic Web infrastructure which is already in place. If your Web site is your API, you can reduce the overall development and maintenance. Similarly, rather than build custom solutions for every Web site you want to pull data from, you can implement one solution based on Semantic Web technologies and have it work interchangeably across many Web sites—including Web sites you weren't even aware of before you began development.
Semantic Web technology overview
Semantic Web technologies can be considered in terms of layers, each layer resting on and extending the functionality of the layers beneath it. Although the Semantic Web is often talked about as if it were a separate entity, it is an extension and enhancement of the existing Web rather than a replacement of it.
Figure 1. The Semantic Web technology stack
As shown in Figure 1, the base layer of the Semantic Web is HTTP and URIs. These are commonly considered 'Web' rather than 'Semantic Web', but every proposed Semantic Web technology rests upon these Web fundamentals. URIs are the nouns of the semantic Web. HTTP are the verbs:
GET,
PUT and
POST as well as a number of thoroughly tested solutions in the fields of authentication and encryption.
The Resource Description Framework (RDF) is the workhorse of the Semantic Web. It is a grammar for encoding relationships. An RDF triple has three components: a subject, a predicate (or verb), and object. Each can be expressed as a resource on the Web, that is a URI. This is far less ambiguous than encoding data in random XML documents. Compare the different ways of expressing a simple relationship in XML given in Listing 1 with the RDF triple in Listing 2.
Listing 1. Ambiguous relationships in XML
Listing 2 shows the RDF triple.
Listing 2. Expressing relationships in RDF
The relationship expressed in all the examples shown in Listing 1 is 'Rob is the author of page'—a fairly simple statement—yet expressed in several ways in XML. It would be very difficult to build software that can derive that relationship from all the possible ways to express it in XML. But an RDF expresses that relationship in only one way, so it becomes feasible to build generic parsers.
In the early days of the Semantic Web, it was hoped that content producers would make all their content available in RDF and soon make a plethora of data available. Unfortunately, perhaps because the main XML expression of RDF looked unnecessarily complex, uptake was slow. More succinct RDF representations, like Notation3 (N3) and Terse RDF Triple Language (Turtle) are now available but have been unable to overcome the inertia. (For more on N3 and Turtle, see Resources.) A solution to the problem was inspired by the Microformats approach. With Microformats, semantic value is added to existing HTML content by using consistent patterns of standard HTML elements and attributes. Microformats exist for narrow but common items of data such as contact information and calendar items. The W3C equivalent is RDFa, RDF data embedded in XHTML. The implementation is slightly more complex than Microformats but it is far more generic—anything which you can express in RDF, you can add to XHTML documents using RDFa. Through this technique the Semantic Web can be bootstrapped by existing Web content.
Of course, the RDF embedded in XHTML documents as RDFa is no good for all the Semantic Web tools, which require RDF as input. There needs to be an automatic method to recognize the presence of RDFa content and extract the RDF out of it. The W3C solution for this is Gleaning Resource Descriptions from Dialects of Languages (GRDDL). The idea is that you run an existing XHTML document through an XSL transform to generate RDF. You can then link the GRDDL transform either through direct inclusion of references or indirectly through profile and namespace documents.
While unambiguously expressed semantics with RDF are good, even if everyone did that, it is of little use if you have no idea how the RDF from different sites is related. The RDF triple in Listing 2 expressed an author relationship in the predicate, and while the meaning might seem obvious to you, computers still need some help. If you expressed an author relationship in an RDF file on your site, could the computer assume they were the same thing? What if you instead had a writer relationship in your RDF triple? What you need is a way to express a common vocabulary, to be able to say that my author and your author are the same thing, or that 'author' and 'writer' are analogous. On the Semantic Web this problem is solved by ontologies, and the W3C standard for expressing ontologies is the Web Ontology Language (OWL). OWL is a large subject in it's own right, and since you're only interested in applications of it in this article, see Resources for more information about it.
Once you have some sources of data in RDF, and you have ontologies to let you determine the relationships between them, you need a way to get useful information out of them. The Simple Protocol and RDF Query Language (or SPARQL, pronounced 'sparkle') is an SQL-like syntax for expressing queries against RDF data, and the queries themselves look and act like RDF data. The fundamental paradigm for SPARQL is pattern matching and it is designed to work across the Web on data combined from disparate sources and to be flexible. For example, matches can be described as optional, which makes it much better than SQL at querying ragged data. Ragged data has an unpredictable and unreliable structure, which is what you might expect to find if your data is combined from various sources on the Web rather than from a single well-contained SQL database.
Things you need to know when planning a Semantic Web site
As you've already seen, if you build the next great Web 2.0 site, you can save time if you plan from the start to embrace Semantic Web technologies and turn your Web site into an API, rather than create a separate API for your Web site. A Semantic Web approach gives you free API-like functionality. Usually an API is a way to get structured data, in XML or JSON format, out of an otherwise unstructured Web site. This leads to a dual approach: You have Web pages for human consumption and you have an API where computers can pull out structured information for automatic processing. However, this creates extra work for you; if you expect people to make use of your API, then you have to document it and support it and keep it synchronized with new features on your Web site. With a Semantic Web approach, your Web site is the structured data. You don't need a separate implementation. You and your users can take advantage of other Semantic Web tools to do automatic processing.
This does raise some issues for planning. With an API you are free to define your own data format for each item of information you want to deliver, and in the Semantic Web this is analogous to defining your own ontology. Ontology design can be a difficult thing to get right with little experience, so you should consider whether any of the large array of existing ones will be suitable for the types of data you plan to use, which will be discussed in the next section. When you design an API, you also usually consider an object model for conceptual organization so developers can understand when they get collections of items or just items, and which collections their items belong in. On a Semantic Web site this will be partly determined by your ontology choices, but also by your URI scheme. Next, you'll look at approaches to making your URIs usable as part of your API.
Finally, on an existing Web site, you and your users can still benefit from the Semantic Web, if you update your content to take advantage of GRDDL, RDFa and Microformats.
Evaluate your data in the context of existing ontologies
A more complex part of the Semantic Web is to design an ontology that matches up to your data. Arriving at the right ontology is usually a critical element of successful implementation of Semantic Web projects. Fortunately, many ontologies already exist. Table 1 lists some of them.
Table 1. Some ontologies in use on the Web today
In addition, many ontologies are domain specific in fields such as technology, environmental science, chemistry and linguistics. These will apply to fewer Web sites than those listed above, however. A lot of your data is likely to fit into at least one of the areas covered by the ontologies in Table 1, in which case you can incorporate them in your planning.
Choose a Semantic URI scheme
If your Web site is your API, then your URIs are the methods that programmers will access to get data. A sensible, succinct and consistent structure is therefore very important, and you need to think about it in advance because frequent changes after everything is launched will cost the goodwill of your target audience. You should also remember that the components of an RDF triple are usually URIs. To change them will invalidate most existing RDF which refers to your Web site.
In the early days of the Web, the structure of the URI usually reflected the
organization of the files on a Web server. If you sold a particular type of widget among
a collection of products, its URI might be similar to:.
The advantage of this approach is that it is relatively semantically clear; if you also
sold a doodad, then an obvious URI where you might expect to find the product details is:.
The relationship between the widget and the doodad is fairly clear. The main problem is that this approach is inflexible; the categorization hierarchy is fixed.
As the Web advanced, dynamically generated sites became the norm. But while the sites
became more flexible, with structure no longer tied to a particular layout of files, the
amount of semantic information in the URI decreased. The page you are shown is determined by some rather cryptic information in the query string. For instance, the URI of the widget might be: and the URI of the doodad might be:.
Suddenly the URI gives you very little semantic value. It's certainly not clear that these two products might be in the same category. More recently, content management systems and Web development frameworks have started to address this issue. Now it's much easier to have semantically structured URIs yet retain the flexibility of dynamic pages. This is achieved through URIs that refer not to a physical file on the server, but to content which can be delivered from a script or page in a different location. In the trend-setting Ruby on Rails framework. this is achieved through routes (rules that map matching URLs to specific controllers and actions). In CMS packages, the feature usually depends on Apache's mod_rewrite (or equivalent on other Web servers) and is often referred to as "Search Engine Friendly URIs" or something similar. When you choose a CMS or development framework for your site, be sure to investigate what it is capable of in this regard.
One final note: If possible, consider removing file name extensions from your URIs.
The filename extensions (.html and .cgi) provide no semantic information that is relevant to the user and actually cause problems in the long run. If you changed your Web site to use PHP instead of CGI scripts, you suddenly have different URIs but serve exactly the same content. This is bad for the semantic value of your URIs, as well as your Google ranking! A more semantically elegant method is to take advantage of the HTTP headers to do content negotiation. Consider the following URI:.
A Web browser will generally indicate its preferred content type using the Accept HTTP header. When asked for this resource, the Web server can check that header, note that text/html is one of the options, and serve an HTML page. If you have a mashup application that wants RDF, then the Accept header in the HTTP request should contain application/rdf+xml and the Web server, from the same URI, can serve an RDF version of the page.
At present this content negotiation functionality is not available in many off-the-shelf CMS solutions, but in the short term it should be possible for a lot of them to use URIs without file extensions, which means you can add this functionality in the future without upsetting your URI scheme.
Take advantage of existing semantic add tools
Whether you fully embrace the Semantic Web in your Web site infrastructure, or just want to make your existing content more useful, there are probably several opportunities to add structure to existing content on your Web site. This is the domain of Microformats, RDFa and GRDDL. Table 2 lists the more common information types that you can easily mark up as structured data.
Table 2. Opportunities for structured markup and automatic transformation
Adding the structured markup to your page is fairly simple. Listings 3 and 4 below show a fragment of HTML containing contact information without, and then with, the additional markup required for the RDF vCard, respectively.
Listing 3. Unstructured contact information
Listing 4 shows the contact information with additional markup required for the RDF vCard.
Listing 4. Contact Information using vCard
In Listing 4, you can see span elements added to delimit the
semantically significant bits of text, and attributes that indicate what they mean. You
added the namespace "contact" linked to the RDF VCard vocabulary. Next, you indicated
that this element is about the resource represented by the URI. Then, you added metadata using the
rel attribute for link relationships and the property attribute on non-links. The only
slightly complex part is the telephone because you need to specify a type as well as the
number. To achieve this, you nest the type and value elements inside the tel element. Adding this structure allows users to add the contact details to their address book with a single click of the mouse.
Other automatic processing is possible with the other structured forms; for example, Technorati makes use of the rel-tag microformat to categorize its vast aggregation of blog posts. A rel-tag is shown in Listing 5, and as you can see, it is simply a link that makes use of the rel attribute. The significant part is the last bit of the URI, after the final /. This is the tag (using the normal URI encoding conventions where a space is represented by the plus sign).
Listing 5. rel-tag for Technorati for the tag 'semantic web'
If you write a blog post related to the Semantic Web that includes the code from Listing 5 and then ping Technorati to let them know you made a new post (a lot of blog software can be configured to do this automatically), then their crawler will index your post and add a summary of it to the page that your tag element links to, along with any other posts with the same tag (see Figure 2).
Figure 2. The 'semantic web' page on Technorati, generated from rel-tag
In this article, you saw how Semantic Web technologies address the need for structured data on the Web in a standard and consistent manner, in contrast to the currently popular method of each Web site defining their own API. You looked at how the Semantic Web technologies add value in layers on top of the HTTP and URIs of the existing Web, first allowing the unambiguous expression of relationships with RDF, and then allowing for shared meaning with OWL based ontologies and finally querying the distributed Web of knowledge using SPARQL. The article also looked at how you can take advantage of existing ontologies to define what your data is and use a semantic URI scheme to enable your Web site to also be your API. Finally the article looked at how you can upgrade the content of your existing Web site using RDFa and Microformats so that GRDDL services can automatically extract RDF from your pages..
Learn
- The ultimate mashup—Web services and the semantic Web (Nicholas Chase, developerWorks, August 2006): Practice using Semantic Web techniques with this six-part tutorial series.
-.
- Programmable Web: Stay up to date with the latest on mashups and the new Web 2.0 APIs.
- The Structured Web - A Primer: Read a general introduction to the value of structured data.
- The W3C's RDF Primer: Learn the basics of RDF and how to use it effectively.
- A Semantic Web Primer for Object-Oriented Software Developers: Read how to use Ontologies, such as RDF Schema and OWL, in the context of OOP.
- The W3C's OWL Overview: Get an understanding of what OWL can do for apps that process information content instead of just presenting it to humans.
- The SPARQL Query Language for RDF specification: Explore the syntax and semantics of this query language for RDF.
- Notation3: Read about N3, a compact and readable alternative to RDF's XML syntax.
- Terse RDF Triple Language: Check out Turtle, a textual syntax for RDF that writes RDF graphs in a compact and natural text form, with abbreviations for common usage patterns and datatypes. Turtle is compatable with existing N-Triples and Notation 3 formats and the triple pattern syntax of SPARQL.
- Cool URIs for the Semantic Web: Read guidelines for effective URIs as the link between RDF and the semantic Web.
- University of Southampton Department of Electronics and Computer Science: See a semantic Web site in action.
- RDFa or Microformats: Embed semantic information in your Web IBM developerWorks XML zone: Learn more about XML and the Semantic Web.
- The technology bookstore: Browse for books on these and other technical topics.
Get products and technologies
-.
Rob Crowther is a Web Developer from London. He has a keen interest in Web Standards and blogs sporadically at. | http://www.ibm.com/developerworks/xml/library/x-plansemantic/index.html | crawl-002 | refinedweb | 3,402 | 58.21 |
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Chapter 13. Developing an application for the JBoss EAP image
To develop Fuse applications on JBoss EAP, an alternative is to use the S2I source workflow to create an OpenShift project for Red Hat Camel CDI with EAP.
Prerequisites
- Ensure that OpenShift is running correctly and the Fuse image streams are already installed in OpenShift. See Getting Started for Administrators.
- Ensure that Maven Repositories are configured for fuse, see Configuring Maven Repositories.
13.1. Creating a JBoss EAP project using the S2I source workflow
To develop Fuse applications on JBoss EAP, an alternative is to use the S2I source workflow to create an OpenShift project for Red Hat Camel CDI with EAP.
Procedure
Add the
viewrole to the default service account to enable clustering. This grants the user the
viewaccess to the
defaultservice account. Service accounts are required in each project to run builds, deployments, and other pods. Enter the following
occlient commands in a shell prompt:
oc login -u developer -p developer oc policy add-role-to-user view -z default
View the installed Fuse on OpenShift templates.
oc get template -n openshift
Enter the following command to create the resources required for running the Red Hat Fuse 7.10 Camel CDI with EAP quickstart. It creates a deployment config and build config for the quickstart. The information about the quickstart and the resources created is displayed on the terminal.
oc new-app s2i-fuse7-eap-camel-cdi --> Creating resources ... service "s2i-fuse7-eap-camel-cdi" created service "s2i-fuse7-eap-camel-cdi-ping" created route.route.openshift.io "s2i-fuse7-eap-camel-cdi" created imagestream.image.openshift.io "s2i-fuse7-eap-camel-cdi" created buildconfig.build.openshift.io "s2i-fuse7-eap-camel-cdi" created deploymentconfig.apps.openshift.io "s2i-fuse7-eap-camel-cdi" created --> Success Access your application via route 's2i-fuse7-eap-camel-cdi-OPENSHIFT_IP_ADDR' Build scheduled, use 'oc logs -f bc/s2i-fuse7-eap-camel-cdi' to track its progress. Run 'oc status' to view your app.
- Navigate to the OpenShift web console in your browser (, replace
OPENSHIFT_IP_ADDRwith the IP address of the cluster) and log in to the console with your credentials (for example, with username
developerand password,
developer).
- In the left hand side panel, expand
Home. Click
Statusto view the
Project Statuspage. All the existing applications in the selected namespace (for example, openshift) are displayed.
Click
s2i-fuse7-eap-camel-cdito view the
Overviewinformation page for the quickstart.
Click the
Resourcestab and then click the link displayed in the Routes section to access the application.
The link has the form. This shows a message like the following in your browser:
Hello world from 172.17.0.3
You can also specify a name using the name parameter in the URL. For example, if you enter the URL,, in your browser you see the response:
Hello jdoe from 172.17.0.3
- Click
View Logsto view the logs for the application.
To shut down the running pod,
- Click the
Overviewtab to return to the overview information page of the application.
- Click the
icon next to Desired Count. The
Edit Countwindow is displayed.
- Use the down arrow to scale down to zero to stop the pod.
13.2. Structure of the JBoss EAP application
You can find the source code for the Red Hat Fuse 7.10.
13.3. JBoss EAP quickstart templates
The following S2I templates are provided for Fuse on JBoss EAP:
Table 13.1. JBoss EAP S2I templates | https://access.redhat.com/documentation/en-us/red_hat_fuse/7.10/html/fuse_on_openshift_guide/develop-jboss-eap-image-application | CC-MAIN-2022-33 | refinedweb | 577 | 58.28 |
On 05/28/2012 03:41 PM, Fabio M. Di Nitto wrote: > On 05/28/2012 04:55 PM, Digimer wrote: >> > > we already have those lists in place. we just don't use them a lot. > > ; >> >> >> >> If there was to be a merger, I would think that choosing an existing one >> would be best to help avoid this. "Linux-cluster" is pretty generic and >> might fit. > > I generally don't like to go into "politics" but that would be the first > point of friction. linuc-cluster, while i agree it sounds neutral, it is > associated with RHCS and other people are more religious about naming > that others. > >> >> I understand that devs working on project like having a dedicated list >> for their project of interest. For this reason, I decided not to press >> this any more. > > The idea is not bad, don't get me wrong, I am not turning it down. Let's > find a neutral namespace (like ha-wg) and start directing all users of > the new stack there. > > Per project mailing list needs to exist for legacy and they will slowly > fade away naturally. Some project will keep them alive for patch posting > others will do what they. >> > > Yup.. so far, the major players have always been crosslooking at > different mailing lists, so the problem is not that bad as it sounds, > but i still agree (as it was discussed before IIRC) a common "umbrella" > would help the final users. > > Fabio Well then, I will un-abandon my position to not proceed.? -- Digimer Papers and Projects: | https://www.redhat.com/archives/linux-cluster/2012-May/msg00049.html | CC-MAIN-2016-44 | refinedweb | 258 | 81.33 |
Terry J. Reedy <tjreedy at udel.edu> added the comment: As a native speaker, I agree that the sentence, in isolation, is hardly comprehensible. The previous one is also a bit flakey. The situation is that top-level code executes in a module named __main__, which has one joint global/local namespace that is the global namespace for all subsidiary contexts. '__main__':<__main__ module> is added to sys.modules before user code is executed. The name __main__ is not normally in the __main__ (global) namespace, hence the comment about 'anonymous' in the first sentence. (It is not anonymous in sys.modules.) However (1) __main__ or any other module/namespace can 'import __main__' and get the reference to __main__ from sys.modules and (2) __main__ does have name __name__ bound to the *string* '__main__'. Hence a module can discover whether or not it *is* the __main__ module. Part of the quoting confusion is that unquoted names in code become strings in namespace dicts, and hence quoted literals when referring to them as keys. What I did not realize until just now is that the __name__ attribute of a module *is* its name (key) in the module namespace (sys.modules dict). For instance, after 'import x.y' or 'from x import y', x.y.__name__ or y.__name is 'x.y' and that is its name (key) in sys.modules. So it appears that the __name__ of a package (sub)module is never just the filename (which I expected), and "__name__ is the module name" only if one considers the package name as part of the module name (which I did not). The only non-capi reference to module.__name__ in the index is 3.2. The standard type hierarchy Modules "__name__ is the module’s name" But what is the modules name? Its name in sys.modules, which is either __main__ or the full dotted name for modules in packages (as I just learned). Perhaps this could be explained better here. ---------- nosy: +terry.reedy _______________________________________ Python tracker <report at bugs.python.org> <> _______________________________________ | https://mail.python.org/pipermail/docs/2012-June/008984.html | CC-MAIN-2016-36 | refinedweb | 342 | 67.55 |
Node:The flexibility of for, Next:Terminating and speeding loops, Previous:for, Up:Loops
The flexibility of
for
As mentioned above, C's
for construct is quite versatile. You can
use almost any statement you like for its initialization,
condition, and increment parts, including an empty
statement. For example, omitting the initialization and
increment parts creates what is essentially a
while loop:
int my_int = 1; for ( ; my_int <= 20; ) { printf ("%d ", my_int); my_int++; }
Omitting the condition part as well produces an infinite
loop, or loop that never ends:
for ( ; ; ) { printf("Aleph Null bottles of beer on the wall...\n"); }
You can break out of an "infinite loop" with the
break or
return commands. (See Terminating and speeding loops.)
Consider the following loop:
for (my_int = 2; my_int <= 1000; my_int = my_int * my_int) { printf ("%d ", my_int); }
This loop begins with 2, and each time through the loop,
my_int
is squared.
Here's another odd
for loop:
char ch; for (ch = '*'; ch != '\n'; ch = getchar()) { /* do something */ }
This loop starts off by initializing
ch with an asterisk. It
checks that
ch is not a linefeed character (which it isn't, the
first time through), then reads a new value of
ch with the
library function
getchar and executes the code inside the curly
brackets. When it detects a line feed, the loop ends.
It is also possible to combine several increment parts in a
for loop using the comma operator
,. (See The comma operator, for more information.)
#include <stdio.h> int main() { int up, down; for (up = 0, down=10; up < down; up++, down--) { printf("up = %d, down= %d\n",up,down); } return 0; }
The example above will produce the following output:
up = 0, down= 10 up = 1, down= 9 up = 2, down= 8 up = 3, down= 7 up = 4, down= 6
One feature of the
for loop that unnerves some programmers is
that even the value of the loop's conditional expression can be altered
from within the loop itself:
int index, number = 20; for (index = 0; index <= number; index++) { if (index == 9) { number = 30; } }
In many languages, this technique is syntactically forbidden. Not so in the flexible language C. It is rarely a good idea, however, because it can make your code confusing and hard to maintain. | http://crasseux.com/books/ctutorial/The-flexibility-of-for.html | CC-MAIN-2017-43 | refinedweb | 374 | 64.14 |
[CENTER]Array of PHP functions shuffle and popTell us which function we'll study this stop...
pg_insert[/CENTER]
Uhm, no.
Ok, here's the deal, PHP has a LOT of functions floating around, some dating back to PHP 3. Many are useful, some are dubious, and some are outright harmful to use in modern code because there are better options out there. pg_insert and it's brethren in the pg_* family of functions (ah, the days before namespaces) are in that last group.
Use PDO. But rather than flatly give that fiat let me explain what PDO is and why you should use it.
PDO was introduced by PHP 5.2 - maybe a little before that - and was a PECL library for some time before being coopted to the PSL (PHP Standard Library). By itself it provides a uniform interface for access to database systems. An argument for PDO is not an argument against your favorite database engine - the whole point of PDO is that you can use it with your favorite database engine. For central library authors it means they can provide solutions without worrying overmuch about which database the end user decides to deploy.
PDO's most powerful ability is the concept of prepared statements and bound data. Prepared statements help to avoid SQL injection hacks by sending the query data and the variables it is acting on in separate steps. Also prepared statements allow the database engine to preserve and reuse prepared statements.
Can PDO replicate pg_insert? No, but PNL\Database can, and it's built on PDO. I'm going to present it now as a preview to the rest of that framework (Hey what can I say, it's my pet) and as a way of presenting an implementation of PDO and an extension of it.
You may have used database classes before or even wrote one. After all, passing connection resource identifiers and query identifiers is a bit of a pain in the tail. PDO saves us the trouble of doing that, but it's not without a few shortcomings and having some shortcuts to some of its more cryptic commands won't hurt. PDO is divided into a database core class - PDO - and a statement class - PDO_Statement. To have a truly flexible extension of PDO we must address both.
We'll begin with the code that extends PDO. The code that follows is PHP 5.4+ safe, so be careful with the bleeding edge there.
<?php
namespace PNL;
/**
* PNL core database extends the PDO library.
* @author Michael
*
*/
class Database extends \\PDO {
protected $tierCollator = null;
protected $treeCollator = null;
One nice thing about namespaces - we don't have to worry with obscure names for things. PDO is in PHP's core namespace, so it really can't have a straightforward name like Database without backward compatibility breaks. PNL\Database doesn't have this problem. As for the collators and what they do - we'll worry with them for another day or maybe later in the thread but I will say they are kinda awesome.
/**
* CONSTRUCT. Convert the configuration array into a DSN and pass that down to
* PDO.
* @param array $config
*/
public function __construct( array $config ) {
assert (
((isset($config['database']) && $config['database']) ||
(isset($config['dsn']) && $config['dsn'])) &&
isset($config['user']) && isset($config['password'])
);
assert might be the most powerful underused function in PHP. Use it - a well placed assert can avoid hours of bug hunting. Here we are asserting that we have some sort of config.
if (isset($config['dsn'])) {
// If a DSN is set use it without question.
parent::__construct($config['dsn'], $config['user'], $config['password']);
} else {
// Otherwise hash the vars we were given into a DSN and pass that.
$params = array(
'driver' => isset($config['driver']) ? $config['driver'] : 'mysql',
'database' => $config['database'],
'user' => $config['user'],
'password' => $config['password'],
'server' => isset($config['server']) ? $config['server'] : 'localhost',
'port' => isset($config['port']) ? $config['port'] : '3306'
);
try {
// Start underlying PDO library.
parent::__construct("{$params['driver']}:dbname={$params['database']};host={$params['server']};port={$params['port']}",
$params['user'],
$params['password']
);
} catch ( \\PDOException $e ) {
throw new ConnectivityException($e);
}
}
One criticism I have of PDO's design is creating an instance of the class implicitly calls a connect request on the target database. In my mind that should be a separate step to make testing easier even if it makes end use a little harder. Constructors should get the object to a ready for use state, and that's all they should do. Then again, the argument can be made that connecting is part of that ready for use state.
// Set the error mode and the two most frequently used collators.
$this->setAttribute(self::ATTR_ERRMODE, self::ERRMODE_EXCEPTION);
$this->tierCollator = isset($config['tierCollator']) ? $config['tierCollator'] : __NAMESPACE__.'\\\\TierCollator';
$this->treeCollator = isset($config['treeCollator']) ? $config['treeCollator'] : __NAMESPACE__.'\\\\TreeCollator';
PDO allows us to choose whether it kicks errors or throws exceptions when a query doesn't parse. I prefer exceptions so that a try/catch approach can be used to the data handling. Our last statement in the construct is the trickiest.
// Now set the standard behaviors of the PNL Framework
$this->setAttribute(self::ATTR_STATEMENT_CLASS, array(isset($config['statement']) ? $config['statement'] : __NAMESPACE__.'\\\\Statement', array($this)));
}
The statment class PDO uses is a settable attribute. PNL goes further to make it a configurable one ($config ultimately comes from a config.ini file). If a statement isn't specified we default to the framework's own which will be covered later in this post. The final array is the arguments that will be passed to that statement. PNL's Statement object receives a reference to the database that spawned it.
public function __get( $var ) {
if ($var == 'tierCollator') {
return $this->tierCollator;
} else if ($var == 'treeCollator') {
return $this->treeCollator;
} else {
trigger_error( "Database::__get: No Access to {$var} or it does not exist", E_USER_NOTICE);
return null;
}
}
public function __set ( $var, $val ) {
if ($var == 'tierCollator' || $var == 'treeCollator') {
if (!class_exists($val)) {
throw new Exception("Collator must be set to a valid class");
}
$this->$var = $val;
} else {
trigger_error( "Database::__set: No Access to {$var} or it does not exist", E_USER_NOTICE);
return null;
}
}
}
PDO has no public variables. The collators can be fetched or set. Their own public properties and modes are accessed in this manner.
So much for the database class. There isn't much here because PDO already does a lot and there isn't much I can add to it to make it any better. Now to the statement object. Most of what I have to say about it is in the comment text.
<?php
namespace PNL;
/**
* PNL core database extends the PDO library to make it more chaining friendly. The
* result and results methods handle most of the more common fetch cases with PDO.
* That said, all PDO functionality remains exposed.
*
* @author Michael
*
*/
class Statement extends \\PDOStatement {
/**
* The database object that created us.
* @var Database
*/
protected $db = null;
protected $key = null;
/**
* Protected is NOT an error here, the PDOStatement object is a PHP internal
* construct and for whatever reason it is protected instead of being public
* like all other PHP constructors. Thank you Zend Engine team - this makes
* it impossible to test this object without also testing the Database object.
*
* @param PDO $db
*/
protected function __construct( $db ) {
$this->db = $db;
}
/**
* Replacement for the execute statement under most circumstances, but parse
* returns the statement object itself to allow for chaining. Also, the
* input array does not have to have leading colons on the key names. If present
* they are left alone, but any string key without a lead colon will have one
* appended.
*
* @param array input parameters for query.
* @see PDOStatement::execute()
* @return this
*/
public function parse( $params = null ) {
if (is_array($params) && !hasAllNumericKeys($params)) {
$params = $this->prepareArray($params);
}
$this->execute( $params );
return $this;
}
The sharp eyed will not hasAllNumericKeys isn't a PHP core function - it is a PNL core function. This is what is known as a dependency, and tracking these things is what keeps programmers up late at night coding something that mysteriously broke. So, as an aside let's look at that function...
function hasAllNumericKeys( array $array = array() ) {
foreach( array_keys($array) as $key) {
if (!is_numeric($key)) {
return false;
}
}
return true;
}
Tiny little bugger. In a Class based world the trend has been in PHP to move all functions into classes. I believe that in a few corner cases that's a mistake. This little function has nothing to it that calls out "I'm a database function" as opposed to "I'm a controller function". It's task as straightforward as its name, so it exists as a separate function from the class in the \PNL namespace where any class of the framework might reference it. Is this a dependency nightmare waiting to happen?
Answer - it could be. Indeed, that 'call from anywhere approach' that you can see a lot of in PHP 4 programs is what makes them so tangled. But there are ways to ensure testability with a function like this. First - it has no internal state. That is, it doesn't remember anything from one call to the next about what it did. Second, it has no global references. global is the single most evil statement in PHP - and the use of global variables will in short order insure that a program becomes utterly untestable. Third, it returns what it returns and doesn't affect anything else. The array it receives is not altered in any way. The function could perhaps take the array by reference, but even that's a mistake because the PHP engine already preserves memory by deferring copying the value until an alteration will occur, which with this function, will not.
With these guidelines followed universal functions can be used. There won't be a lot of them though - PHP already has most of these straightforward situations covered.
We now return to the statement object
/**
* Prepares an array for use as a query parameter set.
*
* @param array $params
* @return array
*/
protected function prepareArray( $params ) {
$return = array();
// No pass by reference here because key values will be changing.
foreach ( $params as $key => $value ) {
if (!is_numeric($key) && strpos($key, ':') !== 0) {
$key = ':'.$key;
}
if (is_array($value)) {
throw DatabaseException('Array Values not permitted');
}
$return[$key] = $value;
}
return $return;
}
/**
* A chainable #closeCursor.
* @see PDOStatement::closeCursor()
* @return this
*/
public function closeQuery() {
$this->closeCursor();
return $this;
}
/**
* A chainable #bindValue;
* @see PDOStatement::bindValue()
* @return this
*/
public function bindVal($parameter, $value, $data_type = \\PDO::PARAM_STR ) {
parent::bindValue($parameter, $value, $data_type);
return $this;
}
Chainable means you can write code in a sentence form like this
$db->prepare($sql)->bindVal('col1', $col1)->bindVal('col2', $col2)->bindVal('col3', $col3)->results();
You'll see this coding style a lot more often in Java and Java Script than PHP, but I believe that's due to lack of support for the technique in frameworks and core code moreso than in comprehension problems. If anything, I find statement chains much easier to read than statement series.
/**
* Bind an array to the statement. If the keys are named you must use named
* placeholders in your statement. If the keys are not named you must use
* question mark placeholders.
* @param array $array
*/
public function bindArray( $array ) {
$array = $this->prepareArray($array);
foreach ( $array as $key => $value ) {
$this->bindValue( is_numeric($key) ? $key+1 : $key, $value, is_int($value) ? \\PDO::PARAM_INT : \\PDO::PARAM_STR );
}
return $this;
}
This is the function that replicates what pg_insert can do in this manner..
$db->prepare("INSERT INTO myTable ( col1, col2, col3 ) VALUES ( :col1, :col2, col3 )")->bindArray($values)->parse();
And now to a couple of icing functions.
/**
* Return a single value, or a single row, as determined by your query structure.
* @return string
*/
public function result() {
return $this->columnCount() == 1 ?
$this->fetchColumn() :
$this->fetch( \\PDO::FETCH_ASSOC );
}
/**
* The return of this function is influenced by your query structure.
* If your query only has one column of results, that column is returned.
* If your query has two columns of results, the first column is returned as the key
* and the second column is returned as the value.
* If there are three or more columns to your query the results are indexed by the first
* field of the query and then grouped on that field.
*
* @return array
*/
public function results() {
return $this->columnCount() == 1 ?
$this->fetchAll( \\PDO::FETCH_COLUMN ) :
$this->fetchAll(\\PDO::FETCH_GROUP|\\PDO::FETCH_UNIQUE|( $this->columnCount() == 2 ? \\PDO::FETCH_COLUMN : \\PDO::FETCH_ASSOC));
}
}
Results isn't without limitations. For the most part it assumes you're going to be getting keyed results. If this isn't the case then it's appropriate to fall back to PDO's fetch and fetchAll statements.Not that there's anything wrong with PDO's fetch statements - but these aliases are quicker to read and use in most cases. There are two more functions in the class that deal with the collators, but as they are way outside of scope for a forum post, and since they are still buggy (which is the reason the framework hasn't been released yet) I'll omit them.
I hope all of this has been informative and useful.
I don't see anything powerful in prepared statements in most use cases. And the concept of prepared statements doesn't belong to PDO - it only adds a nice little convenience to be able to use named placeholders instead of ? characters.
I have tried prepared statements and to me they only make my code less readable. It's still fairly acceptable when there are few bound parameters but if there are many of them so that the SQL statement takes more than one screen and then it is followed by the binding part which must match then the code becomes segmented. I must admit it is nice to see the clean and neat :vars in SQL but then we have to follow all those :vars with appropriate bindings - why make the code segmented? I find the dirty old-style string concatenation to be easier to maintain in the long run because of the linear nature of code - when I look at my SQL I can immediately see where each field value comes from. However, I don't see anything powerful in binding values - this is messy at worst and an unnecessary alternative way of doing the same thing at best.
I think PDO promotes overuse of prepared statements. Their purpose is to increase performance when the same statement with different parameters needs to be executed many times so that the db server can cache the execution plan and then simply accept only values for that statement. Then binding values also makes sense because PHP doesn't need to pass the values from variables - once they are bound there's no need to pass anything. Other than that I think prepared statements provide no benefit and make the code longer and a little bit more complicated. They are not necessary to guarantee security as there are other ways to do it.
In fact I think pg_insert is a very nice function. I don't mean to say that it should be used because it's experimental but the concept is good: to simplify a very common db task. You can insert all values into a table with a single statement - isn't that great? Technically, PDO is very good but alas it lacks methods to access the db easily and often adds complexity where it is not necessary. Instead, it tries to be like a java-style library where when you want to perform a simple task (like formatting a number) you need to go through instantiating 3 objects... PDO is nice to learn OOP on - but when I'm coding I'd rather send all my data to something like pg_insert and be done with it than prepare my statements and bind values. I would like to see (pg_)insert added to PDO! But I'm 99% certain this won't happen
This is not a criticism of the code samples and explanations you provided - actually it's a nice little tutorial. I"m just sharing my personal opinion on the matter. All this unnecessary hassle only in the name of security. There are so many inconveniences authorities throw on us in saying it's for our 'security'... But I digress :). Just learning to escape properly is all that is needed for security.
I'll be the first to admit, that I was dead set against PDO, then for my latest project I decided I'd bite the bullet and use PDO exclusively to put my money where my mouth is (so to speak). Surprisingly I found that I could abstract 98% of the Database interactions I needed to the point, the developer didn't even know he was generating SQL statements behind the scenes. The OO nature of PDO allowed me to hide all but 2% of the SQL generation (the 2% was rare edge cases that likely won't get used often). It took some time but in the end, I ended up with an API that felt natural and the owner of the project (who isn't a programmer) can even write API calls to get the data he wants.
Now sure, you could do this with the typical mysql_* and mysqli_* functions and hide them within a class, but in essence you just created PDO in doing that. It was actually a very redeeming feeling for me to be able to see PDO in that light, as a way to further abstract your data access and database interaction rather than viewing it in the typical ways I used the mysql_* and mysqli_* functions. It gave me much more clarity as to what could be done when approached with a new mindset versus looking at just putting it in where my calls already exist mimicking what is already happening in a more verbose manner.
Just wanted to share that experience, as I found it enlightening. I kind of wish I could share the end result but the client loved it so much, he bought the rights to it from me, so I can't. I'd have to reproduce it which would take a few months (plus it was heavily developed around their system and its structure -- so it isn't a one fit all solution).
Yeah, abstracting SQL is another thing and I don't doubt you can do great things with PDO. But let's focus on the topic we have here - inserting new rows. Can you share some insight how you made database inserts nicely abstracted and in what respect PDO proved superior over mysqli? Of course, as far as you are allowed to
In my opinion, abstracting PDO and then still forcing people to use SQL is entirely redundant and pointless. You're far, far, better off with a simple ORM that allows you to escape the mess of horribly non-OO inflexible SQL code in your application logic. And whether that ORM uses SQL (or PDO, or MySQLI) is irrelevant. pg_insert. Meh, this is better:
$user = $mapper->create();
$user->name = 'Tom';
$user->website = '';
$mapper->save($user);
Using an abstracted PDO within the mapper is equally pointless, the point of the abstraction of PDO is to make SQL simpler to write, but the mapper prevents you needing to write SQL in the first place.
Yes, I was able to hide the SQL generation for inserts, updates, deletes, and so forth. Inserts were similar to what TomB describes, but not quite the same either.
TomB, you are absolutely correct, a simple ORM is a very good option here and I also don't think it matters in this case which db library is used behind the scenes - that's why I'm wondering what benefits cpradio got from PDO as opposed to Mysqli. If his code for inserts is similar to this then I don't really see any special role of PDO here (unless the goal is to target multiple database types, then it gets a bit easier).
My point is - even when you craft your own db abstraction class then somewhere on a deeper level the code needs to generate SQL. It can be done either by escaping values with a dedicated function or by using prepared statements. I simply have doubts that PDO's prepared statements are powerful in anyway for this usage - just a different way of doing the same thing with more lines of code. And in this case it's most probably used only once when coding the abstraction library and then we forget about it using the ready-made mechanisms.
For one, I got a lot of performance out of it since there was a major need for bulk inserts and bulk updates (where prepared statements helped a lot), then the ability to easily extract the values from the queries and auto bind them later provided a great deal to the abstraction, the user didn't need to know the table structure, the query syntax, the names of the parameters to bind their values to, etc. They simply needed to know the API which hide just about everything. Barely anything was noticeable in a select fashion, as that data was usually cached and only ran once against the database for days up to a week.
I just found it far easier to build upon a library, such as, PDO easier from an abstraction and API standpoint than I ever did with the mysqli OO and procedural implementations (not sure why entirely, but it felt like it was more accessible to me). Sure you can accomplish it with mysqli, but it didn't feel as natural to me to extend upon (that could also be because over the last few years, I've picked up on a lot more techniques I've learned from other languages and how they abstract their data access and so I was able to use those same ideas/implementations). | http://community.sitepoint.com/t/php-function-of-the-week-pg-insert-moreover-a-lesson-on-phps-largest-pitfall/27888 | CC-MAIN-2015-40 | refinedweb | 3,632 | 60.65 |
To continue our example we had uploaded EmpDetails Spreadsheet in our very first post to Google Docs. This spreadsheet has four columns and five rows into it. We will add some blank rows and columns in this spreadsheet using our .NET interface.
To start with, I have following controls on my .NET form. There are two buttons and one listview control. The button "Pull Spreadsheet List" will read all the available Spreadsheets available in my Google Doc account and add it into Listview1 control. For button "Add Blank rows/Columns" the concept is after clicking on this button the .NET code logic will interact with the selected spreadsheet and add blank rows and columns into it.
using Google.GData;using Google.GData.Client;using Google.GData.Extensions;using Google.GData.Spreadsheets;
We need a form level variable so we declared it at form level.
public partial class Form1 : Form { string spreadsheetName;
The .NET code logic on the "Pull Spreadsheet List" button is following. The code will pull the spreadsheet list from Google Doc.
private void button1_Click(object sender, EventArgs e) { listView1.Columns.Add("SpreadSheet Name"); listView1.Columns.Add("Summary"); listView1.Columns.Add("Published Date"); listView1.FullRowSelect = true;) { listView1.Items.Add(new ListViewItem(new string[] { mySpread.Title.Text, mySpread.Summary.Text, mySpread.Updated.ToShortDateString() })); } }
I have following .NET code logic on Listview1 SelectedIndexChanged event to store the Spreadsheet name the user has selected.
private void listView1_SelectedIndexChanged(object sender, EventArgs e) { spreadsheetName = ""; ListView.SelectedListViewItemCollection SpreadsheetList = listView1.SelectedItems; foreach (ListViewItem item in SpreadsheetList) { spreadsheetName = item.SubItems[0].Text.ToString(); }}
The code logic for button "Add Blank rows/Columns" is following. We are adding 10 rows and 8 columns into the spreadsheet.
private void button2_Click(object sender, EventArgs e) { if (spreadsheetName.Length > 0) {) { if (mySpread.Title.Text == spreadsheetName) { WorksheetFeed wfeed = mySpread.Worksheets; foreach (WorksheetEntry wsheet in wfeed.Entries) { //Add Blank rows and columns wsheet.Rows = 10; wsheet.Cols = 8; wsheet.Update(); } } } System.Windows.Forms.MessageBox.Show("Rows and Columns Added Successfully"); } }
After setting up the code, I connected to internet and run the form. The first thing I did was to click on Pull Spreadsheet list. The code logic on this button pulled all the spreadsheet available to my Google Doc. The next thing I did was to select EmpDetails Spreadsheet and click on button Add Blank rows/Columns. The code logic runs successfully and pop-up the message that Blank rows and columns have been added successfully.
I log into my Google Doc account to verify this and blank rows and columns were added successfully.
So our objective to add blank rows and columns was achived.Thanks for reading till this point. | http://beyondrelational.com/modules/24/syndicated/398/Posts/15312/spreadsheet-api-how-to-add-blank-rows-and-columns-to-google-spreadsheet.aspx | CC-MAIN-2013-20 | refinedweb | 439 | 61.53 |
Bring back Error Console to Seamonkey after removal in Bug 1278368.
RESOLVED FIXED in seamonkey2.47
(NeedInfo from
Status
▸
General
People
(Reporter: frg, Assigned: frg, NeedInfo)
Tracking
(Blocks: 1 bug)
SeaMonkey Tracking Flags
(seamonkey2.43 unaffected, seamonkey2.44 unaffected, seamonkey2.45 unaffected, seamonkey2.46 unaffected, seamonkey2.47 fixed)
Details
Attachments
(2 attachments, 4 obsolete attachments)
Bug 1278368 removed the error console. make installer is currently broken because of it. We need to either do this too or fork the code over to suite. I am for forking if feasible. The new one has much more functionality but is clumsy to use if you only want to check things out quick.
+1 for forking. So, the idea is to keep the old error console in parallel to the new devtools? Similar to the DOM Inspector? (though that one is an extension anyway...)
>> So, the idea is to keep the old error console in parallel to the new devtools? That would be my plan. Like it is now in 2.45 and 2.46. FRG
I have started with a fork. Needs some tinkering before a patch is ready. If the decision later is to remove it I will just use it in my private tree :) FRG
Created attachment 8768146 [details] [diff] [review] 1282286-ForkConsole-WIP.patch WIP patch. Works with classic theme. Will likely not work with modern theme. Testing this next. Paths might not be optimal. Took out an ifdef in custom.css for windows. Would need a preprocessor step otherwise and already has a -moz-os-version: windows-xp in it so I think it's not needed. Questions: Where should the icons reside finally. Chrome locations ok?
Assignee: nobody → frgrahl
Status: NEW → ASSIGNED
Attachment #8768146 - Flags: feedback?(philip.chee)
Attachment #8768146 - Flags: feedback?(iann_bugzilla)
Oh I forgot. Should we keep the Ctrl+Shift+J access key as it is taken by the new console?
Bug reports against the old Error Console were recently closed because Firefox's new Browser Console supposedly does not have those problems. With the forking to retain Error Console in SeaMonkey, will those bug reports be reopened? More important, will any of them be fixed?
My guess is we'd have to reopen/refile them as SeaMonkey bugs.
I am against just reopening and assigning them to Seamonkey. When I look at old Seamonkey bugs I see a lot which might no longer be valid. Lets first port it and then new ones can be filed if necessary in followp bugs.
Btw. The devtools browser console will be there too so if you need new functionality please file a bug against it. I just want the old one around for quick checks if something is wrong. The fancy stuff should go in the new console. FRG
Agreed to both points.
Comment on attachment 8768146 [details] [diff] [review] 1282286-ForkConsole-WIP.patch Review of attachment 8768146 [details] [diff] [review]: ----------------------------------------------------------------- shouldn't there be entries in the suite/installer/package-manifests.in? i.e. @RESPATH@/components/jsconsole-clhandler.manifest @RESPATH@/components/jsconsole-clhandler.js or something like that?
Created attachment 8769418 [details] [diff] [review] 1282286-interimfix.patch >> shouldn't there be entries in the suite/installer/package-manifests.in? They are still there. The patch doesn't have them because they were currently not removed. But that also means that make installer will fail right now. How about an interim patch until the console is ready for action again?
Attachment #8769418 - Flags: review?(ewong)
Created attachment 8769446 [details] [diff] [review] 1282286-errorconsole.patch This one works. Set windowtype to suite:console from global:console and changed -jsconsole command line parameter to -oldconsole so that it does not interfere with the Borwser console (which did over ride this starting with 2.45 anyway). Need to test on Linux and Windows XP. Anyone able to do and test an osx build?
Attachment #8768146 - Attachment is obsolete: true
Attachment #8768146 - Flags: feedback?(philip.chee)
Attachment #8768146 - Flags: feedback?(iann_bugzilla)
Attachment #8769446 - Flags: review?(philip.chee)
Attachment #8769446 - Flags: review?(iann_bugzilla)
Created attachment 8769449 [details] [diff] [review] 1282286-errorconsole-V2.patch Minor fix for XP icons. Override for console-toolbar.png was not ok. Tested with Linux and seems to be ok there.
Attachment #8769446 - Attachment is obsolete: true
Attachment #8769446 - Flags: review?(philip.chee)
Attachment #8769446 - Flags: review?(iann_bugzilla)
Attachment #8769449 - Flags: review?(philip.chee)
Attachment #8769449 - Flags: review?(iann_bugzilla)
Installer temporary fix I will put it back into the main patch once I got some feedback on this one.
(In reply to Frank-Rainer Grahl from comment #15) > Installer temporary fix > > > > I will put it back into the main patch once I got some feedback on this one. Why not ifdef?
(In reply to Frank-Rainer Grahl from comment #15) > Installer temporary fix > > > > I will put it back into the main patch once I got some feedback on this one. I have used that since June 29. ;)
>> Why not ifdef? Only two lines which can be put back easily. FRG
Comment on attachment 8769449 [details] [diff] [review] 1282286-errorconsole-V2.patch This looks good to me and certainly works, but I would like to have history imported from the original files. I think Ratty may have done it before but there is also a few guides available on how to do it. f+ for the moment.
Attachment #8769449 - Flags: feedback+
Comment on attachment 8769449 [details] [diff] [review] 1282286-errorconsole-V2.patch Now the pain of file copy/history is over, this patch can be rebased. Thanks.
Attachment #8769449 - Flags: review?(philip.chee)
Attachment #8769449 - Flags: review?(iann_bugzilla)
File copy/history landed as
Comment on attachment 8769449 [details] [diff] [review] 1282286-errorconsole-V2.patch I did flatten the structure so that console/content/ -> console/ but if you prefer to have a content/ folder then that is not an issue. >+++ b/suite/common/console/jsconsole-clhandler.js >@@ -0,0 +1,40 @@ >+/* -*- indent-tabs-mode: nil; js-indent-level: 4 -*- */ >+/* vim:sw=4:sr:sta:et:sts: */ Nit: This line is incomplete, my editor complains that */ is an unknown option for sts >+ if (!cmdLine.handleFlag("oldconsole", false)) Maybe errorconsole instead of oldconsole? >+ wwatch.openWindow(null, "chrome://communicator/content/console/console.xul", "_blank", Nit: bring "_blank", onto the following line. >+ "chrome,dialog=no,all", cmdLine); >+ helpInfo : " --oldconsole Open the Error console.\n", Maybe errorconsole instead of oldconsole? >+++ b/suite/common/console/jsconsole-clhandler.manifest >+category command-line-handler t-jsconsole @mozilla.org/suite/console-clh;1 Should this be changed from "t-jsconsole" to something like "s-errorconsole"? >+++ b/suite/common/console/tests/.eslintrc This didn't make into the file copy, do we actually want it? >+++ b/suite/common/console/tests/chrome.ini >@@ -0,0 +1,4 @@ >+[DEFAULT] >+skip-if = buildapp == 'b2g' Does this make any sense to us? >+++ b/suite/common/console/tests/test_hugeURIs.xul >@@ -0,0 +1,64 @@ >+<?xml version="1.0"?> >+<?xml-stylesheet type="text/css" href="chrome://global/skin"?> global or communicator? Have you tested this test? >+++ b/suite/common/jar.mn >-% overlay chrome://global/content/console.xul chrome://communicator/content/consoleOverlay.xul >+% overlay chrome://communicator/content/console/console.xul chrome://communicator/content/consoleOverlay.xul Could we not merge consoleOverlay.xul into console.xul now? (and associated files) - maybe in a follow-up patch so we can get this landed quickly. > % overlay chrome://help/content/help.xul chrome://communicator/content/helpOverlay.xul Similarly for this in helpviewer?
Created attachment 8775128 [details] [diff] [review] 1282286-errorconsole-V3.patch >> I did flatten the structure so that console/content/ -> console/ but if you I am fine with it. >> Maybe errorconsole instead of oldconsole? I choose option 3 and named it suiteconsole. errorconsole is used in m-c for the devtools console. But the window and menu still say 'Error Console' so you decide if suiteconsole is ok or just use errorconsole. >> Should this be changed from "t-jsconsole" to something like "s-errorconsole"? I left it as it is. Changing the manifest file was educated guesswork anyway and it corresponds to the source name this way:) >> >+++ b/suite/common/console/tests/.eslintrc >> This didn't make into the file copy, do we actually want it? I removed the tests dir. The fix made it a long time ago into the tree and I doubt we will make any further changes to the console unless its broken. >> Could we not merge consoleOverlay.xul into console.xul now? I will do a follow-up patch.
Attachment #8769449 - Attachment is obsolete: true
Attachment #8775128 - Flags: review?(iann_bugzilla)
Summary: Port changes from Bug 1278368 to Seamonkey. Error Console has been replaced by Browser Console. → Bring back Error Console to Seamonkey after removal in Bug 1278368.
Comment on attachment 8775128 [details] [diff] [review] 1282286-errorconsole-V3.patch >+++ b/suite/common/console/console.css >@@ -1,66 +1,66 @@ > /* This Source Code Form is subject to the terms of the Mozilla Public > * License, v. 2.0. If a copy of the MPL was not distributed with this > * file, You can obtain one at. */ > Nit: Extra blank line. > > .console-box { >+++ b/suite/common/console/console.xul >-<?xml-stylesheet >+++ b/suite/themes/classic/jar.mn >+#ifdef XP_WIN >+% override chrome://communicator/skin/console/console-toolbar.png chrome://communicator/skin/console/console-toolbar-XP.png osversion<6 >+#endif >\ No newline at end of file Nit: can this be fixed whilst you're here? r=me with those addressed.
Attachment #8775128 - Flags: review?(iann_bugzilla) → review+
Created attachment 8775155 [details] [diff] [review] 1282286-errorconsole-V3a.patch Lates round of nits taken care of. Review+ from IanN carried forward.
Attachment #8775128 - Attachment is obsolete: true
Attachment #8775155 - Flags: review+
Could someone test next mac nightly build if its ok. If not please reopen.
Status: ASSIGNED → RESOLVED
Last Resolved: 2 years ago
status-seamonkey2.47: affected → fixed
Resolution: --- → FIXED
Fixed for 2.47
Target Milestone: --- → seamonkey2.47
Flags: needinfo?(philip.chee) | https://bugzilla.mozilla.org/show_bug.cgi?id=1282286 | CC-MAIN-2018-17 | refinedweb | 1,636 | 53.58 |
Created on 2012-04-07 00:19 by py.user, last changed 2012-04-29 08:50 by ezio.melotti. This issue is now closed.
0[xX][\dA-Fa-f]+ -> (0[xX])?[\dA-Fa-f]+
The documentation appears to be correct to me. Can you demonstrate your suggestion with some examples?
the prefix "0x" is not necessary for the %x specifier in C
if the pattern will see "ABC", it will not match with it, but it should match
#include <stdio.h>
int main(void)
{
unsigned n;
scanf("%x", &n);
printf("%u\n", n);
return 0;
}
[guest@localhost c]$ .ansi t.c -o t
[guest@localhost c]$ ./t
0xa
10
[guest@localhost c]$ ./t
a
10
[guest@localhost c]$
[guest@localhost c]$ alias .ansi
alias .ansi='gcc -ansi -pedantic -Wall'
[guest@localhost c]$
I checked Standard C by Plauger & Brodie and as I read it, it agrees with py.user and his C compiler. For stdlib strtol() and strtoul(), the 0x/0X prefixes are accepted but optional for explicit base 16. If base is given as 0, they are accepted and set the base to 16 (which is otherwise 10). Except for %i, Xscanf functions apparently call either of the above with an explicit base, which is 16 for the %x specifiers.
the same problem in the %o analog
valid strings for the %x specifier of scanf():
"+0xabc"
"-0xabc"
"+abc"
"-abc"
valid strings for the %o specifier of scanf():
"+0123"
"-0123"
"+123"
"-123"
how to patch
the %x specifier:
0[xX][\dA-Fa-f]+ -> [-+]?(0[xX])?[\dA-Fa-f]+
the %o specifier:
0[0-7]* -> [-+]?[0-7]+
New changeset b26471a2a115 by Ezio Melotti in branch '2.7':
#14519: fix the regex used in the scanf example.
New changeset e317d651ccf8 by Ezio Melotti in branch '3.2':
#14519: fix the regex used in the scanf example.
New changeset 7cc1cddb378d by Ezio Melotti in branch 'default':
#14519: merge with 3.2.
Fixed, thanks for the report and the suggestions! | http://bugs.python.org/issue14519 | CC-MAIN-2013-20 | refinedweb | 327 | 75.91 |
import "gopkg.in/webhelp.v1/whlog"
Package whlog provides functionality to log incoming requests and results.
ListenAndServe creates a TCP listener prior to calling Serve. It also logs the address it listens on, and wraps given handlers in whcompat.DoneNotify. Like the standard library, it sets TCP keepalive semantics on.
LogRequests takes a Handler and makes it log requests (prior to request handling). whlog.Default makes a good default logger.
LogResponses takes a Handler and makes it log responses. LogResponses uses whmon's ResponseWriter to keep track of activity. whfatal.Catch should be placed *inside* if applicable. whlog.Default makes a good default logger.
Package whlog imports 7 packages (graph) and is imported by 6 packages. Updated 2017-06-04. Refresh now. Tools for package owners. | https://godoc.org/gopkg.in/webhelp.v1/whlog | CC-MAIN-2020-40 | refinedweb | 126 | 53.27 |
This Tutorial Explains Static Keyword in Java and its Usage in Variables, Methods, Blocks & Classes. Also States the Difference Between Static & Non-static Members:
Java supports various types of declarations to indicate the scope and behavior of its variables, methods, classes, etc. For Example, the keyword final, sealed, static, etc. All these declarations have some specific meaning when they are used in the Java program.
We will explore all these keywords as we proceed with this tutorial. Here, we will discuss the details of one of the most important keywords in Java i.e. “static”.
What You Will Learn:
- Static Keyword In Java
- Conclusion
Static Keyword In Java
A member in a Java program can be declared as static using the keyword “static” preceding its declaration/definition. When a member is declared static, then it essentially means that the member is shared by all the instances of a class without making copies of per instance.
Thus static is a non-class modifier used in Java and can be applied to the following members:
- Variables
- Methods
- Blocks
- Classes (more specifically, nested classes)
When a member is declared static, then it can be accessed without using an object. This means that before a class is instantiated, the static member is active and accessible. Unlike other non-static class members that cease to exist when the object of the class goes out of scope, the static member is still obviously active.
Static Variable in Java
A member variable of a class that is declared as static is called the Static Variable. It is also called as the “Class variable”. Once the variable is declared as static, memory is allocated only once and not every time when a class is instantiated. Hence you can access the static variable without a reference to an object.
The following Java program depicts the usage of Static variables:
class Main { // static variables a and b static int a = 10; static int b; static void printStatic() { a = a /2; b = a; System.out.println("printStatic::Value of a : "+a + " Value of b : "+b); } public static void main(String[] args) { printStatic(); b = a*5; a++; System.out.println("main::Value of a : "+a + " Value of b : "+b); } }
Output:
In the above program, we have two static variables i.e. a and b. We modify these variables in a function “printStatic” as well as in “main”. Note that the values of these static variables are preserved across the functions even when the scope of the function ends. The output shows the values of variables in two functions.
Why Do We Need Static Variables And Where Are They Useful?
Static variables are most useful in applications that need counters. As you know, counters will give wrong values if declared as normal variables.
For instance, if you have a normal variable set as a counter in an application that has a class say car. Then, whenever we create a car object, the normal counter variable will be initialized with every instance. But if we have a counter variable as a static or class variable then it will initialize only once when the class is created.
Later, with every instance of the class, this counter will be incremented by one. This is unlike the normal variable wherein with each instance the counter will be incremented but the value of the counter will always be 1.
Hence even if you create a hundred objects of the class car, then the counter as a normal variable will always have the value as 1 whereas, with a static variable, it will show the correct count of 100.
Given below is another example of Static counters in Java:
class Counter { static int count=0;//will get memory only once and retain its value Counter() { count++;//incrementing the value of static variable System.out.println(count); } } class Main { public static void main(String args[]) { System.out.println("Values of static counter:"); Counter c1=new Counter(); Counter c2=new Counter(); Counter c3=new Counter(); } }
Output:
The working of the static variable is evident in the above program. We have declared the static variable count with initial value = 0. Then in the constructor of the class, we increment the static variable.
In the main function, we create three objects of the class counter. The output shows the value of the static variable each time when the counter object is created. We see that with every object created the existing static variable value is incremented and not reinitialized.
Java Static Method
A method in Java is static when it is preceded by the keyword “static”.
Some points that you need to remember about the static method include:
- A static method belongs to the class as against other non-static methods that are invoked using the instance of a class.
- To invoke a static method, you don’t need a class object.
- The static data members of the class are accessible to the static method. The static method can even change the values of the static data member.
- A static method cannot have a reference to ‘this’ or ‘super’ members. Even if a static method tries to refer them, it will be a compiler error.
- Just like static data, the static method can also call other static methods.
- A static method cannot refer to non-static data members or variables and cannot call non-static methods too.
The following program shows the implementation of the static method in Java:
class Main { // static method static void static_method() { System.out.println("Static method in Java...called without any object"); } public static void main(String[] args) { static_method(); } }
Output:
This is a simple illustration. We define a static method that simply prints a message. Then in the main function, the static method is called without any object or instance of a class.
Another Example of Static keyword Implementation in Java.
class Main { // static variable static int count_static = 5; // instance variable int b = 10; // static method static void printStatic() { count_static = 20; System.out.println("static method printStatic"); // b = 20; // compilation error "error: non-static variable b cannot be referenced from a static context" //inst_print(); // compilation error "non-static method inst_print() cannot be referenced from a static //context" //System.out.println(super.count_static); // compiler error "non-static variable super cannot be //referenced from a static context" } // instance method void inst_print() { System.out.println("instance method inst_print"); } public static void main(String[] args) { printStatic(); } }
In the above program, as you can see we have two methods. The method printStaticis a static method while inst_print is an instance method. We also have two variables, static_count is a static variable and b is an instance variable.
In the static method – printStatic, first, we display a message and then we try to change the value of the instance variable b and also call the non-static method.
Next, we try to use the ‘super’ keyword.
b = 20;
inst_print();
System.out.println(super.count_static);
When we execute the program with the above lines, we get compilation errors for using instance variables, calling non-static methods and referring super in a static context. These are the limitations of the static method.
When we comment on the above three lines, only then the above program works fine and produces the following output.
Output:
Overloading And Overriding Of Static Method
As you all know, both Overloading and Overriding are the features of OOPS and they aid in polymorphism. Overloading can be classified as compile-time polymorphism wherein you can have methods with the same name but different parameter lists.
Overriding is a feature of run time polymorphism and in this, the base class method is overridden in the derived class so that the method signature or prototype is the same but the definition differs.
Let us discuss how Overloading and Overriding affect the static class in Java.
Overloading
You can overload a static method in Java with different parameter lists but with the same name.
The following program shows Overloading:
public class Main { public static void static_method() { System.out.println("static_method called "); } public static void static_method(String msg) { System.out.println("static_method(string) called with " + msg); } public static void main(String args[]) { static_method(); static_method("Hello, World!!"); } }
Output:
This program has two static methods with the same name ‘static_method’ but a different argument list. The first method does not take any argument and the second method takes a string argument.
One point to note is that you cannot overload the method merely depending on the ‘static’ keyword. For Example, if you have an instance method ‘sum’ and if you define another method “sum” and declare it as static, then it is not going to work. This attempt to overload based on a “static” keyword is going to result in a compilation failure.
Overriding
As static methods are invoked without any object of the class, even if you have a static method with the same signature in the derived class, it will not be overriding. This is because there is no run-time polymorphism without an instance.
Hence you cannot override a static method. But if at all there is a static method with the same signature in the derived class, then the method to call doesn’t depend on the objects at run time but it depends on the compiler.
You have to note that though static methods cannot be overridden, the Java language does not give any compiler errors when you have a method in the derived class with the same signature as a base class method.
The following implementation proves this point.
classBase_Class { // Static method in base class which will be hidden in substatic_displayclass public static void static_display() { System.out.println("Base_Class::static_display"); } } classDerived_Class extends Base_Class { public static void static_display() { System.out.println("Derived_Class::static_display"); } } public class Main { public static void main(String args[ ]) { Base_Class obj1 = new Base_Class(); Base_Class obj2 = new Derived_Class(); Derived_Class obj3 = new Derived_Class(); obj1.static_display(); obj2.static_display(); obj3.static_display(); } }
Output:
In the above program, you can see that the static method that is called does not depend on which object the pointer points to. This is because objects are not at all used with static methods.
Static Block In Java
Just as you have function blocks in programming languages like C++, C#, etc. in Java also, there is a special block called “static” block that usually includes a block of code related to static data.
This static block is executed at the moment when the first object of the class is created (precisely at the time of classloading) or when the static member inside the block is used.
The following program shows the usage of a static block.
class Main { static int sum = 0; static int val1 = 5; static int val2; // static block static { sum = val1 + val2; System.out.println("In static block, val1: " + val1 + " val2: "+ val2 + " sum:" + sum); val2 = val1 * 3; sum = val1 + val2; } public static void main(String[] args) { System.out.println("In main function, val1: " + val1 + " val2: "+ val2 + " sum:" + sum); } }
Output:
Note the order of execution of statements in the above program. The contents of the static block are executed first followed by the main program. The static variables sum and val1 have initial values while val2 is not initialized (it defaults to 0). Then in the static block val2 is still not assigned a value and hence its value is displayed as 0.
The variable val2 is assigned value after printing in the static block and the sum is recalculated. Therefore, in the main function, we get different values of sum and val2.
If you specify a constructor, then the contents of the static block are executed even before the constructor. The static blocks are mostly used to initialize static members of the class and other initialization related to static members.
Java Static Class
In Java, you have static blocks, static methods, and even static variables. Hence it’s obvious that you can also have static classes. In Java, it is possible to have a class inside another class and this is called a Nested class. The class that encloses the nested class is called the Outer class.
In Java, although you can declare a nested class as Static it is not possible to have the outer class as Static.
Let’s now explore the static nested classes in Java.
Static Nested Class In Java
As already mentioned, you can have a nested class in Java declared as static. The static nested class differs from the non-static nested class(inner class) in certain aspects as listed below.
Unlike the non-static nested class, the nested static class doesn’t need an outer class reference.
A static nested class can access only static members of the outer class as against the non-static classes that can access static as well as non-static members of the outer class.
An example of a static nested class is given below.
class Main{ private static String str = "SoftwareTestingHelp"; //Static nested class static class NestedClass{ //non-static method public void display() { System.out.println("Static string in OuterClass: " + str); } } public static void main(String args[]) { Main.NestedClassobj = new Main.NestedClass(); obj.display(); } }
Output:
In the above program, you see that the static nested class can access the static variable (string) from the outer class.
Static Import In Java
As you know, we usually include various packages and predefined functionality in the Java program by using the “import” directive. Using the word static with the import directive allows you to use the class functionality without using the class name.
Example:
import static java.lang.System.*; class Main { public static void main(String[] args) { //here we import System class using static, hence we can directly use functionality out.println("demonstrating static import"); } }
Output:
In this program, we use static import for java.lang.System class.
Note: In the main function, we have just used out.println to display the message.
Although the static import feature makes code more concise and readable, it sometimes creates ambiguity especially when some packages have the same functions. Hence static import should be used only when extremely needed.
Static vs Non-Static
Let us discuss the major differences between Static and Non-Static members of Java.
Enlisted below are the differences between Static and Non-Static variables.
Given below is the difference between Static and Non-Static methods.
Static vs Final
Static and Final are two keywords in Java that can give special meaning to the entity that it is used with. For Example, when a variable is declared as static, it becomes a class variable that can be accessed without a reference to the object.
Similarly, when a variable is declared as final, it becomes immutable i.e. a constant.
Let’s tabularize some of the major differences between Static and Final keywords in Java.
Frequently Asked Questions
Q #1) Can Java Class be Static?
Answer: Yes, a class in Java can be static, provided it is not the outer class. This means that only nested classes in Java can be static.
Q #2) When should I use Static in Java?
Answer: Whenever you want a data member in your program that should keep its value across the objects, then you should use static. For Example, a counter. A method can be declared as static when you do not want to invoke it using an object.
Q #3) Can a Static Class have a Constructor?
Answer: Yes, a static class can have a constructor and its purpose is solely to initialize static data members. It will be invoked only for the first time when the data members are accessed. It will not be invoked for subsequent access.
Q #4) What is the use of Static Constructor?
Answer: In general, the constructor is used to initialize static data members. It is also used to perform operations/actions that need to be carried out only once.
Q #5) Are static methods inherited in Java?
Answer: Yes, static methods in Java are inherited but are not overridden.
Conclusion
In this tutorial, we discussed the static keyword of Java in detail along with its usage in data members, methods, blocks and classes. The static keyword is a keyword that is used to indicate the class level or global scope.
You don’t need to access static members using instances of the class. You can directly access the static data members using the class name. We also discussed the major differences between static and non-static members as well as static and final keywords.
In our subsequent topics, we will explore more keywords and their significance in Java language. | https://www.softwaretestinghelp.com/java/static-in-java/ | CC-MAIN-2021-17 | refinedweb | 2,755 | 54.42 |
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How to remove directories and subdirectories from the path specified using c# winform
Hello all,
I want to remove the directories and subdirectories from the path specified using the c# winforms 2003.
For ex:
I am having the path like:
C:\\Program Files\\Test\\all subdirectories, where, "Test"is my folder name and inside the "Test" folder there are some subdirectories.
So, How do I delete the directories and subdirectories from the path specified?
Please help me out?
Thanks in advance.
Delete the data from the Folder and then delete folder using c# 2003
Hello all,
I have a file path like:
"C:\\Test\\Test1"
"Test1" folder is having some files and folders. So, first I want to delete that files and folders from the "Test1" folder and finally deletes the "Test1" folder from the spcified path.
So, How can I do this using the C#.Net 2003 in winforms.
I am doing like the following
userAppData = "C:\\Test\\Test1";
if (System.IO.Directory.Exists(userAppData))
{
System.IO.Directory.Delete(userAppData);
}
else
{
MessageBox.Show("Directory Does Not Exist");
}
"Test 1 folder is not empty".
Please help me out.
Thanks in advance.
- Join Date
- May 2003
- Location
- Washington, DC
- 10,653
- Mentioned
- 4 Post(s)
- Tagged
- 0 Thread(s)
Please don't double post if you don't get an answer to your original question, it is a violation of forum rules.
As for your question, you should go and look at the methods and classes in the System.IO namespace. Everything you need is there.
Bookmarks | http://www.sitepoint.com/forums/showthread.php?497091-How-to-remove-directories-and-subdirectories-from-the-path-specified-using-c-winform&p=3509925 | CC-MAIN-2016-44 | refinedweb | 265 | 65.62 |
Code. Collaborate. Organize.
No Limits. Try it Today.
When using ASP.NET to process online credit card orders, it is a good idea if you can perform some sort of validation on the credit card number before submitting it to your processor. I recently had to write some code to process credit card orders, and thought I’d share a bit of my code.
Fortunately, credit card numbers are created in a way that allows for some basic verification. This verification does not tell you if funds are available on the account, and it certainly doesn’t tell whether or not the person submitting the order is committing credit card fraud. In fact, it’s possible that the card number is mistyped in such a way that it just happens to pass verification. But, it does catch most typing errors, and reduces bandwidth usage by catching those errors before trying to actually process the credit card.
To validate a credit card number, you start by adding the value of every other digit, starting from the right-most digit and working left. number has passed the validation.
Of course, this would be clearer with a bit of code, and Listing 1 shows my IsCardNumberValid method.
IsCardNumberValid
public static bool IsCardNumberValid(string cardNumber)
{
int i, checkSum = 0;
// Compute checksum of every other digit starting from right-most digit
for (i = cardNumber.Length - 1; i >= 0; i -= 2)
checkSum += (cardNumber[i] - '0');
// Now take digits not included in first checksum, multiple by two,
// and compute checksum of resulting digits
for (i = cardNumber.Length - 2; i >= 0; i -= 2)
{
int val = ((cardNumber[i] - '0') * 2);
while (val > 0)
{
checkSum += (val % 10);
val /= 10;
}
}
// Number is valid if sum of both checksums MOD 10 equals 0
return ((checkSum % 10) == 0);
}
The IsCardNumberValid method assumes that all spaces and other non-digit characters have been stripped from the card number string. This is a straightforward task, but Listing 2 shows the method I use for this.
public static string NormalizeCardNumber(string cardNumber)
{
if (cardNumber == null)
cardNumber = String.Empty;
StringBuilder sb = new StringBuilder();
foreach (char c in cardNumber)
{
if (Char.IsDigit(c))
sb.Append(c);
}
return sb.ToString();
}
You will also be able to reduce bandwidth if you can avoid trying to submit a card that is not supported by the business. So, another task that can be useful is determining the credit card type.
public enum CardType
{
Unknown = 0,
MasterCard = 1,
VISA = 2,
Amex = 3,
Discover = 4,
DinersClub = 5,
JCB = 6,
enRoute = 7
}
// Class to hold credit card type information
private class CardTypeInfo
{
public CardTypeInfo(string regEx, int length, CardType type)
{
RegEx = regEx;
Length = length;
Type = type;
}
public string RegEx { get; set; }
public int Length { get; set; }
public CardType Type { get; set; }
}
// Array of CardTypeInfo objects.
// Used by GetCardType() to identify credit card types.
private static CardTypeInfo[] _cardTypeInfo =
{
new CardTypeInfo("^(51|52|53|54|55)", 16, CardType.MasterCard),
new CardTypeInfo("^(4)", 16, CardType.VISA),
new CardTypeInfo("^(4)", 13, CardType.VISA),
new CardTypeInfo("^(34|37)", 15, CardType.Amex),
new CardTypeInfo("^(6011)", 16, CardType.Discover),
new CardTypeInfo("^(300|301|302|303|304|305|36|38)",
14, CardType.DinersClub),
new CardTypeInfo("^(3)", 16, CardType.JCB),
new CardTypeInfo("^(2131|1800)", 15, CardType.JCB),
new CardTypeInfo("^(2014|2149)", 15, CardType.enRoute),
};
public static CardType GetCardType(string cardNumber)
{
foreach (CardTypeInfo info in _cardTypeInfo)
{
if (cardNumber.Length == info.Length &&
Regex.IsMatch(cardNumber, info.RegEx))
return info.Type;
}
return CardType.Unknown;
}
Listing 3 is my code to determine a credit card’s type. I’m a big fan of table-driven code, when it makes sense, and so I created an array of CardTypeInfo objects. The GetCardType() method simply loops through this array, looking for the first description that would match the credit card number being tested. As before, this routine assumes all non-digit characters have been removed from the credit card number string.
CardTypeInfo
GetCardType()
The main reason I like table-driven code is because it makes the code simpler. This results in code that is easier to read and modify. GetCardType() returns a value from the CardType enum. CardType.Unknown is returned if the card number doesn’t match any card descriptions in the table.
CardType
CardType.Unknown
Writing code to process credit cards involves a number of issues that need to be addressed. Hopefully, this code will give you a leg up on addressing a couple of them.
This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)
public enum ISCCN { Good , Bad , Ugly } ;
public static ISCCN
Isccn
(
string Subject
)
{
if ( System.String.IsNullOrEmpty ( Subject ) )
{
throw ( new System.ArgumentException ( "You didn't provide a value" , "Subject" ) ) ;
}
ISCCN result = ISCCN.Ugly ;
if ( ( Subject.Length == 13 ) || ( Subject.Length == 15 ) || ( Subject.Length == 16 ) )
{
int isodd = 1 ;
int checksum = 0 ;
int runner = Subject.Length - 1 ;
while ( ( runner >= 0 ) && ( char.IsDigit ( Subject [ runner ] ) ) )
{
int temp = isodd * ( Subject [ runner-- ] - '0' ) ;
checksum += temp / 10 + temp % 10 ;
isodd ^= 3 ;
}
if ( runner == -1 )
{
if ( ( checksum % 10 ) == 0 )
{
result = ISCCN.Good ;
}
else
{
result = ISCCN.Bad ;
}
}
}
return ( result ) ;
}
General News Suggestion Question Bug Answer Joke Rant Admin
Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages. | http://www.codeproject.com/Articles/36377/Validating-Credit-Card-Numbers?fid=1540623&df=90&mpp=25&noise=3&prof=True&sort=Position&view=None&spc=None | CC-MAIN-2014-23 | refinedweb | 865 | 57.16 |
# Quantum Computers Without Math and Philosophy
In this article, I will break down all the secrets of quantum computers piece by piece: what superposition (useless) and entanglement (interesting effect) are, whether they can replace classical computers (no) and whether they can crack RSA (no). At the same time, I will not mention the wave function and annoying [Bob and Alice](https://en.wikipedia.org/wiki/Alice_and_Bob) that you might have seen in other articles about quantum machines.
The first and most important thing to know is that quantum computers have nothing to do with conventional ones. Quantum computers are analog in nature, they have no binary operations. You have probably already heard about Qubits that they have a state of 0, 1 and 0-1 at the same time and with the help of this feature calculations are very fast: this is a delusion. A qubit is a [magnet](https://physics.stackexchange.com/questions/204090/understanding-the-bloch-sphere) (usually an atom or an electron) suspended in space, and it can rotate on all three axes. In fact, the rotations of a magnet in space are the operations of a quantum computer. Why can it speed up calculations? It was very difficult to find the answer, but the most patient readers will find it at the end of the article.
Superposition
-------------
Before talking about the magical state 0-1 (superposition), let's first understand how the position of the magnet in 3D generally becomes zero and one. When creating a quantum computer, it can be decided that if the North (N) pole of the magnet (blue in the pictures below) looks up then this value is zero, if down then one. When a quantum program is launched, all qubits are set to zero (up) with the help of an external magnetic field. After the completion of the quantum program (a set of rotations of the qubits) it is necessary to obtain the final value of the qubits (to measure them), but how to do this? Qubits are extremely small and unstable. They are negatively affected by thermal radiation (therefore they are greatly cooled) and cosmic rays. You can't just look at a qubit and tell where its N pole is now. The measurement is performed indirectly. For example, you can bring magnets with N pole to the qubit from below and from above.
If the N pole of the qubit was directed upwards, then the qubit would fly down, and just this fall can be registered. After that, the state of the qubit is measured (Zero) and it is no longer physically suitable for further use in the quantum program. This is just an illustrative example, in each quantum computer the measurement is performed by its own methods, it is very difficult to find a description of how exactly, but the essence remains the same.
Now the most interesting, remember that our magnet can rotate in any direction, let's put it on its side? This is where all quantum algorithms start.
Great, we have put the qubit into a state of superposition, the famous "0-1 at the same time". When you try to measure such a qubit, it will fly up or down with the probability of about 50% (depending on the accuracy of building a quantum computer). As you can see, the state of the qubit is known exactly, we just rotated it 90o. Statements that it is at zero and one at the same time (or rushing between them) look strange, because only one sensor will be triggered during a measurement. Rotating another 90o takes the qubit out of the magical state.
Another important point: if the qubit is rotated from the vertical position not by 90o, but only by a couple of degrees, then during the measurement it will fly to "Sensor 0" with a very high probability, and in rare cases to "Sensor 1". This has been proven by experiments, I also tested it myself (IBM gives free access), a single atom behaves more complicated than an ordinary magnet.
Any deviation from the vertical results in a probability of measuring one instead of zero. Accordingly, the initial initialization of qubits and all rotations of qubits must be done very accurately. It is also necessary to protect qubits from external influence very reliably, otherwise you will receive a calculation error. Modern quantum computers have extremely low accuracy, this is their big problem.
Now consider the very popular but misleading claim that superposition speeds up calculations. All quantum algorithms start by setting a group of qubits (register) into a superposition state (turning the magnets on their side). Starting from this moment, official science tells us that one qubit stores 0-1 at the same time, two qubits store 0-3 at the same time, eight qubits store 0-255, and so on. Any mathematical operation on this group of qubits will be performed immediately for all numbers stored by qubits.
Example: we have two groups of 32 qubits (two memory registers), we want to calculate the sum of numbers from these two registers. Performing addition once, we get absolutely all possible combinations of sums of numbers that can only be placed in these two registers. That is, about 18 quintillion addition operations were performed in one physical operation. It sounds very cool, but there is a catch.
After the completion of the quantum algorithm, we need to somehow pull out the result of the calculation. The problem is that a quantum computer won't give us all 18 quintillion results at once. After measurement, it will return only one of them, and that will be a random one. The measurement process destroys the qubits, which means that to get another result we will have to perform the operation again. To get all 18 quintillion results out of a quantum machine, you must run it at least 18 quintillion times.
What is with password cracking? Similarly, to convert the hash sum into a password you must run a quantum program very, very many times (as on a classical computer). Thus superposition (even if it is real) has no effect on the performance of the quantum machine by itself.
Entanglement
------------
Quantum entanglement is the second whale on which the quantum computer is based. This is a curious effect that modern science cannot yet explain. But we will go a long way. Let's look at a typical piece of source code for a classical computer:
```
if (n > 50) then n = 50
```
This line is difficult to execute on a quantum computer. After the operation (n>50), the qubits of the variable n will be immediately physically destroyed (because they had to be measured for the comparison operation), but we need this variable further in the code. Conditional jumps (and loops) are generally not available for quantum computers. How do they even survive then? One IF operation can still be performed, without taking a measurement: controlled NOT (CNOT), this is an analogue of the classical [XOR](https://en.wikipedia.org/wiki/Exclusive_or) operation. Two qubits participate in this operation, controlling and controlled:
* if the N pole of the controlling qubit is pointing down (value 1), then the controlled qubit rotates 180 degrees
* if the N pole of the controlling qubit is pointing up (value 0), then the controlled qubit does not change
This operation allows you to perform a trivial addition of integers for two qubit registers. To perform this operation, two qubits are briefly [brought closer to each other](https://physics.stackexchange.com/questions/173776/how-is-cnot-operation-realized-physically), after which a series of separate rotations is performed. Measurements are not required, i.e., you can work with qubits further. After this operation the qubits are entangled. How does it show up? Let's start with the commonplace:
After we have entangled the qubits, they become dependent on each other. If the Q1 qubit has been measured as One, then the Q2 qubit will be measured as Zero. But this case is obvious and not interesting, let's put the qubits on their side before CNOT:
If the controlling qubit lies on its side, then the controlled one will either be rotated 180 degrees with a 50% probability or remain in the same state. The exact final position of the qubits in 3D space after such an operation is not known (they are allegedly in many states at once), because qubits cannot be viewed directly. But if entangled qubits are measured, then Q1 will randomly fly to sensor 0 or 1, and Q2 will always fly to the opposite sensor.
Why this happens no one knows. Logically, both qubits lie on their sides after the CNOT operation, which means that both should randomly fly on both sensors, without any dependence. In fact, there is a clear connection during the measurement (with some error, the system is analog). There are two theories on this:
* Official science claims that qubits exchange information with each other (it is not known how, but instantly, more than the speed of light). When the first qubit is measured (hit on the sensor), it tells the second qubit exactly where it fell, and the second qubit remembers it and hits the opposite sensor during the measurement. This theory looks very strange, but here we must understand that official science adheres to the principle of superposition, that qubits are in the 0-1 state at the same time: when measuring the first qubit, the second can no longer remain in 0-1, it must urgently decide on the orientation.
* The theory of hidden variables: it says that when interacting, qubits immediately agree on who will fall on which sensor. This happens due to a change in the physical parameter of the qubit, which is not yet known to science. This theory looks more logical, superluminal interactions are no longer required here. But this theory denies the existence of the superposition principle, which is the Holy Grail for modern science, so this theory is not being seriously studied.
In my opinion, the phenomenon of Entanglement itself is the main proof that Superposition does not exist. But I am not a theoretical physicist, so let's leave this topic. In the end, once official science ridiculed the theory of the movement of lithospheric plates, but in the end the guys figured everything out.
A couple final points about entanglement:
* You can entangle many qubits, and this is a common thing for quantum computers. For this you need to run CNOT in turn for several qubits.
* After the CNOT operation, the controlling qubit also changes its orientation in 3D space. Its N pole does not move up and down, but the qubit itself rotates around the Z axis, this phenomenon is called [Phase Kickback](https://towardsdatascience.com/quantum-phase-kickback-bb83d976a448). It is of great importance for quantum algorithms, this is what gives acceleration of calculations. We will talk about this below.
* If, after entanglement, one of the qubits is transferred to the Zero state with the help of an external magnetic field (repeating the initial initialization), then this will not affect the second qubit in any way, the entanglement state will be broken. That is, the exchange of information at superluminal speed cannot be achieved using entanglement.
* Entangled particles are sometimes compared to socks: I put one on my right foot, the second automatically becomes the left sock. This is an incorrect comparison. Entangled particles are more like two coins standing on their side: if one of them falls on heads, then the second will fall on tails, even if several hours have passed.
What Quantum Computers Cannot Do
--------------------------------
Quantum computers are quite slow with a typical operating frequency of 100 MHz, but this is fixable. They are also quite small, 66 qubit machine is considered very good (you can store a couple of Int in memory), but this is also fixable. At the physical level, quantum computers do not (and may never) support:
* conditional jumps and loops (I mentioned this earlier);
* multiplication and division;
* raising to a power and trigonometry.
All interaction between qubits is limited by the CNOT operation. But if quantum computers are so limited, why is there so much hype around them? When solving the problem head-on, there will be no superiority over classical computers, but there is a very short list of algorithms where a quantum computer can show itself. Let me remind you that each quantum operation is the rotation of one or two qubits, and one short-term pulse is enough to perform it. On the other hand, to simulate the rotation of a magnet on a classical computer, you need to calculate a lot of sines and cosines. Approximately on this feature effective quantum algorithms are built.
Shor's Algorithm
----------------
Shor's algorithm has long been a scare on the Internet, as it can theoretically crack RSA quite quickly. The hacking task itself comes down to finding two prime numbers that make up the RSA public key, i.e., we need to find two divisors for a very large number (about 512 bits for RSA-512). A simple enumeration on a classical or quantum computer will take a very long time, and as we saw above, the superposition principle does not help here.
In fact, there are two Shor Algorithms, classical and with quantum addition, let's start with the first one. Mathematicians have determined that the problem of simple enumeration can be replaced by the following equation:
* **a** - the number 2 or 3 (in fact, any number, but 2 or 3 is exactly right, which one of them is impossible to say in advance);
* **N** - the number for which we are looking for divisors (conditionally this is the RSA public key);
* **mod** is an operation that returns the remainder of an integer division;
* **x** is an auxiliary number, having found it (by simple enumeration) we will quickly find the divisors of the number N. The desired x must be greater than zero, even and the minimum of all possible.
Mathematicians have determined that the number of steps to enumerate the number x will be significantly less than a simple enumeration of the numbers a and b using the formula a\*b=N. I checked how it works, ran the formulas in Excel and found the divisors for the number 15: it is enough to iterate over just two numbers x, ignoring 0 and all odd ones.
This effect should be more pronounced for larger numbers, but there is a catch. An experienced eye, of course, noticed the exponentiation operation, as well as the search for the remainder of the division. There may be fewer enumeration steps, but each step itself has become very complex, and their complexity will grow exponentially for large numbers N. Also, you are probably wondering, what does quantum computers have to do with it, if everything worked out in Excel?
Quantum Shor’s Algorithm
------------------------
Shor's quantum algorithm also starts by calculating the formula axmod(N), but there are a lot of problems here:
* raising to the power, multiplication and division (including integer division with remainder) are not supported at the hardware level;
* the number of qubits is very limited, it is problematic to keep the result ax in memory;
* loops are not supported, which means that iterating over the number x must be done without them.
The guys did not despair and came up with a set of workarounds. The number x at the input of the quantum program is given as qubits in superposition. The formula axmod(N) will supposedly be calculated immediately for all possible numbers x in one operation, but as we saw above, this is useless, because we can measure only one result of all, and it will be for random x.
Further, the formula axmod(N) itself is replaced by a very strange code (a simulation of a quantum computer is shown):
```
X = Register('X', 8)
F = Register('F', 4)
X.H()
F[3].X()
for i in range(8):
for j in range(2**i):
Fredkin(X[i], F[0], F[1])
Fredkin(X[i], F[1], F[2])
Fredkin(X[i], F[2], F[3])
```
* **Register** is a function that initializes the specified number of qubits (8 and 4), it returns the register of qubits with the value 0x0 (all N poles are directed upwards);
* method **H** is [Hadamard gate](https://www.quantum-inspire.com/kbase/hadamard/), puts qubits on their side (sets to superposition);
* method **X** rotates a qubit by 180o (like binary NOT);
* **Fredkin** function is standard for quantum computing, it swaps the values of two qubits if the first parameter (controlling) is set to one (N pole is directed downwards). The function consists of 8 CNOT operations and 9 single qubit rotations;
* register **X** stores the number x;
* register **F** stores the result of axmod(N)
The source code is available in my [repository](https://github.com/zashibis/FastQubit).
You are probably very surprised how this can even work? This is a workaround that allows to calculate the formula axmod(N) for a=2, N=15 and any x. There are several [methods](https://arxiv.org/abs/1207.0511) that allow to create a set of qubit rotations for any numbers **a** and **N**. I have no idea how it works, the documentation for quantum algorithms has low quality, but my own tests have confirmed that the calculations are correct.
Accordingly, if we want to crack some RSA-512 key, then first for this particular key we must create a scheme that will include a lot of rotations. But how many times should we run such the scheme? Did you notice the two nested loops in the source code above? For the number N=15, the circuit is launched 255 times, for N=21 - 511 times, for N=35, which is still unattainable by quantum computers, there will be 2047 launches. The number of operations increases dramatically.
Quantum Phase Estimation
------------------------
Congratulations to all the most patient readers, having gone a long way of misunderstanding, we got to the very essence of quantum computers. When we calculate the formula F= axmod(N) on a classical computer, we wait for the value F=1. But when we work on a quantum machine, it doesn’t really matter to us what is ultimately stored in the register F, the solution to the problem will be stored in the input register X.
In the classical computer XOR operator (CNOT analogue) does not change the value of the controlling variable. But let me remind you that when we perform CNOT operation in the quantum machine, it changes both qubits:
* the N pole of the controlled qubit moves up and down, depending on the state of the controlling one;
* the N pole of the controlling qubit does not move up and down, but the qubit itself rotates along the Z axis.
The deviation of the qubit along the Z axis is called the phase. During the execution of a quantum program, all qubits accumulate some phase change. Mathematicians have proven that by measuring the final phase of all qubits in the input register X, it is possible with a very high probability to find the divisors of the number N (to hack RSA), even if the result in the register F is not 1. RSA-512 requires only about 2000 runs of the algorithm on a quantum computer. But there is a catch. Even two.
The first problem is that one must somehow be able to measure the phase. For this, the QFE ([Quantum Phase Estimation](https://qiskit.org/textbook/ch-algorithms/quantum-phase-estimation.html)) algorithm is used, which requires additional rotations of qubits by very small angles. For N=15 you need to rotate the qubits by 1.4o, for N=35 the rotations will be 0.175o. For RSA-512 you need to rotate the qubit by insignificant 180/21022 degrees and doing this 1022 times. Qubits are an analog system, if you make a mistake with the angle then you will get an error at the output. Modern quantum computers cannot cope with the number N=35, they already lack the accuracy of rotations. But this is not the biggest problem, the most insignificant turns can be simply neglected, almost without losing the accuracy of the entire algorithm.
The second problem is the calculation of axmod(N). For RSA-512 it only needs to be calculated 2000 times. But look again at the two nested loops: one such calculation is more than 21022 consecutive rotations of qubits. This is nonsense. Quantum computers are not capable to hack RSA, even if they grow to a million qubits. There are scientific articles about how they managed to optimize this part and make it hundreds and thousands of times faster, but they always keep silent about exactly how many operations are required when N is about 2511.
Quantum Computer Simulators
---------------------------
Quantum computer simulators are much slower than their real counterparts. This happens because simulators do their job honestly. When you create a register of 8 qubits in the simulator, all possible values for these qubits are stored in memory (an array of 256 values is created). If you create two registers of 8 qubits each and perform the A+B operation, the simulator will calculate and store in memory all possible combinations of additions (it will create an array of 65536 values). This will be significantly longer than a single addition operation, but after that the simulator can return all these values to you without destroying the data on each "measurement". To get all the results on a real quantum computer, you will run it at least 65536 times (the result is returned randomly, there may be repetitions), and in general, it will take even longer than on the simulator.
But if qubits are just magnets in 3D space, is it possible to create a simulator that rotates them in virtual reality? I tried and created the [FastQubit](https://github.com/zashibis/FastQubit) library. Most of the operations work successfully (even [Bell states](https://en.wikipedia.org/wiki/Bell_state)), and such a simulator has a significant advantage over the real quantum computer:
* there can be millions of qubits and they are completely stable, no errors;
* qubits can be viewed at any time, the exact position in 3D can be determined, without destroying them.
But there is a catch. Phase Kickback doesn't work correctly in my library:
```
Q[0].H()
Q[1].X()
Q[0].P_pi(8)
Q[1].P_pi(8)
CNOT(Q[0], Q[1])
Q[1].P_pi(-8)
CNOT(Q[0], Q[1])
```
This chain of operations should eventually shift the Q[0] qubit phase by 45o, but in my case, the shift is performed by 90o. The fact is that the exact position of qubits in 3D after the first CNOT operation is not known to science (but he is known after the second CNOT). Here they usually mention superposition, that qubits are in many states at once. I used the documentation for quantum operations and made the turns exactly as they are described there. But no, in fact [no one knows](https://quantumcomputing.stackexchange.com/questions/26257/rxx-gate-as-a-set-of-rotations) what turns are performed.
If you get this short code to work correctly, you may be eligible for a Nobel Prize. But don't try to use a workaround: of course, you can turn the phase to the desired angle under certain conditions, but this will stop working when entanglement between several qubits is added to the quantum program.
Conclusion
----------
The documentation for quantum computers is as pretentious as possible, even elementary things turn into complex formulas. I have spent weeks trying to figure out what is really hidden in them. Articles in the news and blogs, on the contrary, are extremely superficial, philosophical, and very often contain false information. No one ever publishes the number of how many operations are required to hack RSA-512 (and it is not the most crypto-resistant). Instead, you will be shown several formulas for calculating the complexity of the algorithm, making it as incomprehensible as possible.
I am not calling for an immediate end to all funding for quantum computing research. This is fundamental research that can bring unexpected useful results in other areas. But it is necessary to stop publishing scary stories about the post-quantum era. | https://habr.com/ru/post/664810/ | null | null | 4,186 | 50.97 |
I forgot to copy everyone on my original reply to Doug. Doug provided several good patches that will be incorporated. The unicode/latin-1 problem concerns me, so here is my extended response on the character encoding problem with python 2.0.
---------------
Doug,
I'd thought I'd give you a better explaination about what I think is wrong with the unicode-latin1 issue. While your patches work, I think they are treating the symptom, and not the source of the problem.
All internal strings in gramps should be latin-1 encoded. The fact that you have to translate them to latin indicates that there is a problem somewhere that is allowing non-latin-1 characters to get into the data. There are three sources of input at this time - entry into the interface, gramps input file, and GEDCOM.
The entry into the interface should always return latin-1, since gnome does not currently handle unicode. I think we can probably eliminate this one. The gramps input file under python 2.0 uses an encoded input file, that is supposed to translate from unicode to latin-1 as it data is read in. In ReadXML.py you should see around line 71 the following line:
xml_file = EncodedFile(gzip.open(filename,"rb"),'utf-8','latin-1')
It is possible that this is not doing that I think it should.
The third possiblity is in the GEDCOM import. My bet is on this one. It looks as if under 2.0 I am not decoding unicode properly. My guess is that changing lines 32-36 of latin_utf8.py to:
def utf8_to_latin(s):
return s.encode('latin-1')
def latin_to_utf8(s):
return s.encode('utf-8')
might to the trick. I think this patch probably needs to be made.
A couple of questions:
1. Did you originally import your data from a GEDCOM file?
2. Was the GEDCOM file encoded as ASCII, ANSEL, UNICODE, or UTF-8? (check the CHAR line towards the top of the file)
-- Don
Don Allingham
donaldallingham@home.com | http://sourceforge.net/p/gramps/mailman/attachment/991068180.2047.21.camel%40wallace/1/ | CC-MAIN-2015-06 | refinedweb | 340 | 68.47 |
When I was writing 1st part of this article (to see, click here), I was so sure that this article will get least amount of viewers from web. And the main reason behind this thought was, integration of Quickbooks with .NET is certainly a headache of very small amount of .NET programmers. I’m glad I was wrong. Because what I forgot was, there is not much help on this topic on web too. So almost every programmer who has to do such kind of integration would Google on the topic and eventually come to my article. Thus this topic came out to be my 2nd most popular article (1st most popular is here).
In 1st part of this article, I explained how you can connect your web application with Quickbooks, also I dwelled upon application architecture, after successfully connecting with QB I retrieved some records from Vendor table and at the end I explained some necessary settings you need to do in QB so that you can successfully connect you .NET application with it. In this article, I’ll demonstrate how you can add new records in any of the QB tables. I’ll take Vendor table’s example again. I’ll use the same windows desktop application that I created in part 1, and I’m going to add one more win form into it. I’ll make my new win form as start up form of the project and along with other controls that will help in adding a new Vendor, I’ll add a button that will open the View Vendor List form that I created in part 1.
So, if you have not yet read and understood part 1 yet then it’s time that you do so (click here). Because following contents are completely dependant upon the discussion we had in part 1. And if you haven’t received your FREE copy of source code of the project yet then it’s better that you get it now by requesting me nicely in the comments section of this or part 1 of this article.
Now let’s start coding!
In first step, I opened the project I explained in part 1 and added a new form into it, named it frmVendor.cs. Second step I took was, I opened Program.cs and changed its code as follows:
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new frmVendor());
//Application.Run(new frmViewVendorList());
}
So as I said before, I made my frmVendor class as start up form. Third step is a little bit lengthy to explain, so I’ll act upon the famous adage i.e. a picture is worth thousand words. So in third step made UI of frmVendor and made it look like this:
Okay, now let me explain this form, top to bottom, step by step:
- The File field is to make QB file selection dynamic. In part 1, it was hard coded in app.config; so in this form I made it little easier for my fellow programmers so that they can select their own QB file with whatever name they want rather than using my QB file name or going into the code and changing the hard coded name. I’ve defaulted the value in text box with my Quick Book file path but you can use Browse button to select any other file that you would want to work with. Line of code for Browse button is coming in short.
- After adding File name & Browse button, I added a Group box and added some controls for some mandatory fields of Vendor table namely, Name, Type, Company, Contact, Phone, Fax etc.
- Then I added a row of command buttons to:
- Add Vendor: Adds a new Vendor
- Get List: Gets a complete list of vendors from QB and populates the grid control below
- Search: Searches on a particular Vendor on the basis of Vendor Name criteria entered by the user in text box above. This will get a vendor and populate the text boxes placed on the form.
- Clear: This is a typical clear button, clears the form i.e. the text boxes on the form.
- Complete List: Finally the last button, which simply calls the Show All Vendors form that we created in Part 1.
- After row of command buttons, I added a grid view control. This is the smaller and pretty similar version of the grid view I had in part 1. The main purpose of this grid view is to see if the vendor we add from this control really gets added in the QB.
- In the bottom of the form, I have a multiline text box, which will simply serve the purpose of a gigantic status bas. After any operation, we’ll get either success or failure messages in this text box.
Now let’s start coding this form. Again, I’ll start from top to bottom, so let’s see Browse button first:
private void btnBrowse_Click(object sender, EventArgs e)
{
OpenFileDialog ofdQuickBookSelect = new OpenFileDialog();
if (ofdQuickBookSelect.ShowDialog() == DialogResult.OK)
this.txtFile.Text = ofdQuickBookSelect.FileName;
}
This is 2nd simplest piece of code so I’m not explaining any of its part and going to jump to the 1st simplest piece of code i.e. code behind Complete List button:
private void btnShow_Click(object sender, EventArgs e)
{
new frmViewVendorList().ShowDialog(this);
}
Clicking on this button opens Vendor List form as a dialogue box of our current form. Together the two forms look like this, pretty cool huh?
Well, Okay, not that cool, let’s get back to Vendor Form; next, I choose the 3rd simplest piece of code in this form, Clear button’s code:
private void btnClear_Click(object sender, EventArgs e)
{
this.txtResults.Text = this.txtVendorCompany.Text = this.txtVendorContact.Text =
this.txtVendorFax.Text = this.txtVendorName.Text = this.txtVendorPhone.Text = string.Empty;
this.cmbVendorType.SelectedIndex = 1;
}
So simple, no explanation needed, let’s move forward without wasting our time on trinkets. But before going into some difficult piece of code, let me copy-paste two more code snippets that are quite simple on their own, I’m talking about two methods, GetFormVendor() and SetFormVendor(Vendor vendor). These two methods are basically getter and setter of form’s vendor object. If Vendor class looks unfamiliar to you then I can bet you didn’t understand Part 1 of QB integration series of articles. Hence, last warning to you, please go back to Part 1 (click here) and see how I made Vendor class and what this class is capable of; otherwise you won’t understand any of the following discussion. Let’s see the code of the two methods:
private Vendor GetFormVendor()
{
Vendor vendor = new Vendor();
vendor.Name = this.txtVendorName.Text;
vendor.Type = this.cmbVendorType.Text;
vendor.CompanyName = this.txtVendorCompany.Text;
vendor.PhoneNumber = this.txtVendorPhone.Text;
vendor.FaxNumber = this.txtVendorFax.Text;
vendor.ContactName = this.txtVendorContact.Text;
return vendor;
}
private void SetFormVendor(Vendor vendor)
{
this.txtVendorName.Text = vendor.Name;
this.txtVendorCompany.Text = vendor.CompanyName;
this.txtVendorPhone.Text = vendor.PhoneNumber;
this.txtVendorFax.Text = vendor.FaxNumber;
this.txtVendorContact.Text = vendor.ContactName;
this.cmbVendorType.Text = vendor.Type;
}
First method is very simple one, it simply instantiates Vendor class, populate its properties with the values entered in the text boxes on form and returns the object to the caller method. Second method is even simpler, it accepts a Vendor object as a method parameter and sets corresponding text boxes’ values with object properties. Method returns without any return argument. Now as we are moving forward, we are getting out of simple pieces of code snippets. There is only one method left in this category which is as follows:
private void frmVendor_Load(object sender, EventArgs e)
{
string[] vendorTypes = { "Consultant", "Service", "ServiceProviders", "Suppliers",
"Constructor", "Mover", "Builder" };
for (int i = 0; i < vendorTypes.Length; i++)
this.cmbVendorType.Items.Add(new ComboBoxItem(vendorTypes[i].ToString(), i));
}
Yes, that’s right, form load event; this method simply adds some Vendor Types in the drop down list. I hard coded these vendor types, mainly because I know these types are present in my QB file. You can change them as you want or write your own method to get a list of vendor types from QB. If you add a vendor type in this list which, you already know, is not present in QB file, don’t worry, my code is capable of adding that vendor type in QB file first and then adding the vendor you were trying to add. Now we are truly officially out of simple code snippets and going to code little hard piece of code. However, if you have read and understood part 1, even the hardest piece of code in this article will be kids’ stuff for you. It’s the turn of Search button’s code behind, but before I show that code, let me show the top part of frmVendor.cs, the class frmVendor starts like this:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace prjQuickBookIntegration
{
public partial class frmVendor : Form
{
private RequestBroker broker = new RequestBroker();
public frmVendor()
{
InitializeComponent();
}
private Vendor GetFormVendor()
…
…
…
The frmVendor.cs starts with including some standard namespaces, followed by its own namespace. Then we start frmVendor class which has a class level variable as:
private RequestBroker broker = new RequestBroker();
Recall part 1 and the significance of RequestBroker class in this whole story. This class is Data Access Layer of this project, in other words, classes RequestBroker and Vendor together, make the brain of this application. Let’s see Search button’s code behind (line numbers are given for explanation and are not part of the actual code):
private void btnSearch_Click(object sender, EventArgs e)
{
01 broker = (this.txtFile.Text.Length > 0) ? new RequestBroker(this.txtFile.Text) : new RequestBroker();
02 if (this.txtVendorName.Text.Length > 0)
{
03 Vendor vendor = broker.GetVendorsByName(this.txtVendorName.Text);
04 if (vendor.Name.Length > 0)
{
05 SetFormVendor(vendor);
06 this.txtResults.Text = "Vendor found.";
}
else
07 this.txtResults.Text = "Vendor could not be found.";
}
}
Line 01 checks if there is anything given in txtFile then it instantiates RequestBroker class with the file path of QB file, else it instantiates the class by empty constructor. If you give file path in the constructor then RequestBroker will use that particular file otherwise it will use the file path from app.config. A line 02 check if there is some text entered in txtVendorName, since we are searching on vendor name, this field is important. If both of the above two If statements come out to be true then we are all set for vendor search. Line 03 does the actual job. In this line we call broker’s method, GetVendorsByName() and pass vendor name as parameter. This method will go to QB file and search and return a Vendor object if it finds one. Rest of the lines are all decorations, if broker finds a vendor with that name, it will SetFormVendor() method at line 05 and displays a friend message in our big status bar text box that “Vendor found.”; otherwise, display message “Vendor could not be found.”.
Before we move forward in this, let me explain GetVendorsByName() method in broker class, since I didn’t explain it Part 1.
/// <summary>
/// This method gets an active vendor matching name criteria
/// </summary>
/// <returns></returns>
public Vendor GetVendorsByName(string vendorName)
{
QBOperationStatus opStatus = new QBOperationStatus();
01 QBList<Vendor> qblAllVendors = this.GetVendorList(ref opStatus, true);
02 Vendor searchedVendor = qblAllVendors.GetEntity("Name", vendorName);
03 if (searchedVendor == null)
04 searchedVendor = new Vendor();
return searchedVendor;
}
Logic of this method is little nasty, in line 01, I get the complete list of vendors from QB by calling GetVendorList() method. Code of this method is given and explained in Part 1. After we populate our QBList<Vendor> qblAllVendors, we’ll use its own method GetEntity() to filter on “Name” field. If there exists such a vendor with the given name (checked in line 03), then that vendor object will be returned, else line 04, return an empty vendor object. Let’s see how our form looks like when we search on a vendor name, I entered Sam in vendor name text box and selected search button and got the following screen:
At this point, let me clearly mention that all vendor names and their details in these articles are fake and entered by myself. If there is any match found with a real person, company or contact number, it would be a mere coincidence. Anyways, you have to enter such disclaimers clearly in your articles in US in order to save your rear J
After searching a vendor in QB, now let’s see the code behind Get List button:
private void btnVendorList_Click(object sender, EventArgs e)
{
01 broker = (this.txtFile.Text.Length > 0) ? new RequestBroker(this.txtFile.Text) : new RequestBroker();
02 QBOperationStatus opStatus = new QBOperationStatus();
03 this.grdVendors.DataSource = new QBList<Vendor>();
04 QBList<Vendor> qblVendor = broker.GetVendorList(ref opStatus, true);
05 this.grdVendors.DataSource = qblVendor;
06 if (opStatus.OperationResult == QBOperationResult.Succeeded)
07 this.txtResults.Text = qblVendor.Count.ToString() + " records retrieved successfully.";
else
08 this.txtResults.Text = "Vendors could not be retrieved successfully.\r\n" + opStatus.Message;
}
Logic of this method is exactly the same as you’ve already seen in part 1 of QB integration. Let’s briefly skim through the lines of this method. Line 01 checks if QB file path is given or not. Line 02 instantiates QBOperationStatus class, which will be used in next step when we’ll be getting vendor list from broker object; QBOperationStatus has been explained in detail in Part 1. In line 03, I’m assigning an empty vendor list to gird view control just to clear & clean the grid from previous data. Line 04 gets all the vendors from QB by calling broker’s method GetVendorList(). In line 05, I assign the list returned by broker class to the grid view, so if the list is empty, it will have no effect on the grid; if there is some data in the list, then it will populate the grid view. Rest of the lines are decorative again. Line 06 checks if the recent operation with QB was successful or not; if yes, then show a friendly message in status bar; if no, then show failure message in status bar. Selecting Get list button will give you the following screen:
Now let’s see the crux of this article, Add Vendor. Code behind Add Vendor button is as follows:
private void btnAddVendor_Click(object sender, EventArgs e)
{
01 Vendor vendor = GetFormVendor();
02 broker = (this.txtFile.Text.Length > 0) ? new RequestBroker(this.txtFile.Text) : new RequestBroker();
03 QBOperationStatus opStatus = broker.AddVendor(vendor);
04 if (opStatus.OperationResult == QBOperationResult.Succeeded)
this.txtResults.Text = "Vendor added successfully.";
else
this.txtResults.Text = "Vendor could not be added successfully.\r\n" + opStatus.Message;
}
This method is a clear example of the fact that how easy and convenient, programming becomes if the application is well designed and well architected in multi layers. Line 01 populates a Vendor object from the form text boxes. In this version of the application, there are no required field validation and no data validation checks; so it is advised not to play with the application with the intention to break the code or to crash it; because at this point the application is very fragile. Line 02 instantiates RequestBroker class. Line 03 calls broker’s AddVendor() method and passes Vendor object to it as an input parameter. AddVendor() method either adds the vendor into QB and returns the status successful; or, it fails for some reason and returns the status failed. Depending upon the status, line 04 displays the message in status bar. Broker’s AddVendor() is as follows:
public QBOperationStatus AddVendor(Vendor vendor)
{
QBOperationStatus opStatus = new QBOperationStatus();
try
{
01 opStatus = this.AddVendorType(vendor);
02 if (opStatus.OperationResult == QBOperationResult.Succeeded)
{
03 opStatus = BeginSession();
04 if (opStatus.OperationResult == QBOperationResult.Succeeded)
{
05 IMsgSetRequest requestSet = CreateRequestMsgSet();
06 IVendorAdd vendorAddRequest = requestSet.AppendVendorAddRq();
07 vendor.FillAddRequest(ref vendorAddRequest);
try
{
08 IMsgSetResponse responseSet = this.GetResponse(requestSet);
09 this.sessionManager.CloseConnection();
10 opStatus = GetResponseStatus(responseSet);
}
catch (Exception ex)
{
11 opStatus.OperationResult = QBOperationResult.Failed;
12 opStatus.Message += " Unexpected error " + "\r\n";
}
}
}
}
catch (Exception ex)
{
13 opStatus.Message = ex.Message;
}
finally
{
14 this.sessionManager.EndSession();
}
15 return opStatus;
}
In line 01, I’m calling AddVendorType() method of broker class. I’m passing fully populated vendor object to this method and it will add its type in Quickbooks. If the type is already there, it won’t add a duplicate one; if it’s not there, then vendor type will be added. Code of AddVendorType() is coming shortly. Line 02 checks what is the operation status after adding vendor type. Line 03 begins the session with QB (code of method BeginSession() coming shortly), followed by line 04, which again checks the operation status after beginning session with QB. Line 05 calls CreateRequestMsgSet() method (code coming shortly); the purpose of this method is, while adding a new vendor we need to set a message request of QBSessionManager class which is part of Interop.QBFC7 namespace and explained in Part 1 of this article. CreateRequestMsgSet() method returns an object of IMsgSetRequest which is again a part of Interop.QBFC7. This class is used in line 06, where we call its AppendVendorAddRq() method and get an object of IVendorAdd class. The logic behind getting an object of IVendorAdd is, QB doesn’t know our Vendor business object; it has its own business objects and what you have to do is, before asking QB to add a vendor, you have to populate its IVendorAdd object. Doing so is tantamount to calling an INSERT statement of SQL Server. Thus, when you populate IVendorAdd object, it actually adds a vendor in QB if all validations are successful. In line 06 we just created this object, but in line 07 we call Vendor class’s method FillAddRequest() to populate IVendorAdd object. Code of FillAddRequest() is coming shortly. In line 08, 09 and 10, I’m get the response from QB, closing session and getting operation status respectively. In case of an exception, I’ll set operation status and status message in line 11, 12 and 13. Line 14 ends the session with QB and line 15 returns the status of the above operation to the caller method.
Let’s take a look at AddVendorType() method called in line 01. This method is a public method of broker class and its code is as follows:
public QBOperationStatus AddVendorType(Vendor vendor)
{
QBOperationStatus opStatus = new QBOperationStatus();
try
{
opStatus = BeginSession();
if (opStatus.OperationResult == QBOperationResult.Succeeded)
{
IMsgSetRequest requestSet = CreateRequestMsgSet();
IVendorTypeAdd vendorTypeAddRequest = requestSet.AppendVendorTypeAddRq();
vendor.FillAddTypeRequest(ref vendorTypeAddRequest);
IMsgSetResponse responseSet = this.GetResponse(requestSet);
this.sessionManager.CloseConnection();
opStatus = GetResponseStatus(responseSet);
if (opStatus.Message.IndexOf("the list element is already in use") > -1)
opStatus.OperationResult = QBOperationResult.Succeeded;
}
}
catch (Exception ex)
{
opStatus.Message = ex.Message;
}
finally
{
this.sessionManager.EndSession();
}
return opStatus;
}
The above method adds a vendor type, if it’s not already there. Some other methods that you might need to see are as follows:
private QBOperationStatus BeginSession()
{
QBOperationStatus opResult = new QBOperationStatus();
try
{
this.sessionManager = new QBSessionManagerClass();
this.sessionManager.OpenConnection(string.Empty, RequestBroker.ApplicationName);
opResult.Message = "\r\nConnection opened successfully.";
this.sessionManager.BeginSession(RequestBroker.CompanyFilePath, ENOpenMode.omMultiUser);
opResult.Message += "\r\nSession begin Successfully";
opResult.OperationResult = QBOperationResult.Succeeded;
}
catch (Exception ex)
{
opResult.OperationResult = QBOperationResult.Failed;
opResult.Message += "\r\n" + ex.Message + " App name: " + RequestBroker.ApplicationName + " Company file: " + RequestBroker.CompanyFilePath;
//opResult.Message += "\r\n---" + ex.ToString();
}
return opResult;
}
private IMsgSetRequest CreateRequestMsgSet()
{
IMsgSetRequest requestMsgSet = null;
try
{
requestMsgSet = this.sessionManager.CreateMsgSetRequest(RequestBroker.QBVersion.country,
RequestBroker.QBVersion.majorVersion, RequestBroker.QBVersion.minorVersion);
requestMsgSet.Attributes.OnError = ENRqOnError.roeContinue;
}
catch (Exception ex)
{
}
return requestMsgSet;
}
The above given methods are part of RequestBroker class. After the above two methods now we need to go to Vendor class and add the following two methods:);
}
Remember: All the code given in this article is addition to the code written in Part 1 of the article. So in order to get complete code of your classes you’ll have to merge code from Part 1 and this part. Well, after placing all the code at proper places, my Add Vendor button is ready to roll. I filled in all the fields and selected Add Vendor button, I got a message saying “Vendor added successfully”. To confirm, I clicked on “Get List” button and I got the following screenshot with the newly added vendor in the bottom of the list:
I hope you’ve noticed that previously there were 51 total vendors in the system and now after adding the new one, we’ve got 52.
So all of the folks who have to integrate Quickbooks with .NET applications, I hope I’ve made your lives little easier by posting this article, if I really did then don’t forget to post your feedback.
And yes, don’t forget to request for your FREE copy of the source code; have a great day and happy programming!
🙂
Hi,
Great Article.
I would like to appreciate your affort in writing this article. Great work.
Can you please sent me the project code/files.
I need to develop a mediator application to transfer data from Practice Partners to Quick books.
Just studying he requirements..
It would be of great help.
Here are my emailIds
mallesh.varri@gmail.com
mallesh.varri@hotmail.com
malleshv@convene-tech.com
Thanks in Advance..
Comment by Mallesh — July 10, 2009 @ 11:51 am
Hi,
please send me the code.
KHAN
Comment by Khan — July 22, 2009 @ 10:44 am
This is a great article
Could you please send me the complete code at j4v4jive@yahoo.com
Thanks in advance
Comment by John — August 3, 2009 @ 10:59 pm
Hey there buddy – can I get a copy of that code? I’m running a proof of concept and this would be perfect.
Thanks for the great kickstart!
Comment by William — August 5, 2009 @ 4:25 pm
Dude I’m so sorry my hotmail id is screwed up and i’m unable to send any e-mails to gmail addresses. Give me your hotmail or yahoo id so that I can forward you the zip file with source code.
Comment by Mukarram Mukhtar — August 5, 2009 @ 5:41 pm
Great article (and the first one, too). Could I have a copy of the source for both articles? Thanks!
Comment by Scott — August 9, 2009 @ 2:12 pm
Great article.. Please send me the source code to my email:thanukk@yahoo.com
Comment by Thanu K — January 27, 2010 @ 4:12 am
As you’ll see in the comments, I was unable to get a copy of the source, but looking at this post and his other, I was able to generate all the proof of concepts that I needed. I was able to “fill in the gaps” so to speak. And built a functioning app to connect to QB. You should make this source code downloadable!
Comment by William — January 28, 2010 @ 10:42 pm
Great article (and the first one, also). Can you forward source code of both to my email.bavna14@yahoo.com
Comment by bavna — January 31, 2010 @ 2:47 pm
Hei Mukarram,
Which all are the softwares and tools to be installed for doing QuickBook integration with .Net.If trail/free versions of QuickBook are available,plz give the link for the same.
Thanks,
Binto
Comment by Binto — February 4, 2010 @ 5:36 am
Not much idea buddy, I never intended to use the free version. You can check out their official website ( ), if not the free version, they might be offering big discounts in the begining of the year.
Comment by Mukarram Mukhtar — February 4, 2010 @ 10:10 pm
Great Article regarding quick book integration.I have few more queries regarding this.Can you please clear the following queries:
1)Which all are the file formats supported by Quick Book?
2) Can .qbw files be opened in windows?
3)Using asp.net,can we create a file with .qbw extension?
Thanks in advance
Binto
Comment by Binto — March 11, 2010 @ 11:51 am
Thanks a lot again for such a great article.It would be appreciated,If you could clear my queries.
1)Are .QLX files support QuickBook?
2)Can we able to make any QuickBook supported files using ASP.net and integrate the created files with QuickBook?
Thanks in Advance,
Bavna
Comment by Bavna — March 11, 2010 @ 12:17 pm
@ Binto & Bavna,
I’ll try to do some research on the questions you asked, and will send e-mails to you instead of replying here. These days I’m very busy at my work and studies so I’m sorry if it takes a little long. Secondly I would encourage you to find out a solution of these questions and write your own blog; this might help other novice programmers to share your knowledge.
Comment by Mukarram Mukhtar — March 16, 2010 @ 12:21 pm
Saludos desde Ecuador:
Muy buen artículo me podrías enviar el código fuente de la aplicación a mi correo luisico52@hotmail.com y gracias por este muy buen aporte sigue adelante
Hasta pronto
Javier
Comment by Javierq — May 14, 2010 @ 9:56 pm
This is really Great Article regarding Quick Book Integration. Can you please send the source code to rahulmtc@hotmail.com
Comment by Rahul — July 26, 2010 @ 5:46 am
Hi,
Great artical, only issue i have is that i’m more of a VB.NET developer and it took me a while but i was able to rewrite this code in VB.NET. Also, this code was written for a desktop application, but i’ve had to create a web application. I ended up creating my own base classes instead of using the collectionsBase class i’ve created a base class from the List(Of T) Generics.
This artical was excellent. Good work!!
Comment by Shurland Moore — August 20, 2010 @ 5:02 pm
Great Article for QuickBook Integration. Can you send me the source code for this article.
My e-mail ID is pinky_1863@yahoo.co.in
Comment by Pinky Patel — August 27, 2010 @ 2:32 pm
Hi Mukarram,
Fantastic article! Please can you send me the source code. ty_moodley@yahoo.com
Comment by Tyrone Moodley — September 13, 2010 @ 4:41 am
Hello Mukarram.
Great article.
I would appreciate it if you could send me the code to hazal_29@hotmail.com.
Thank you ver much.
Comment by Axel — September 20, 2010 @ 5:52 pm
Can you send me source coce on anant.radadia@gmail.com.Thank you very much.
Comment by anant — October 21, 2010 @ 8:09 pm
Great artical
can you send me the code to kajal_2811@yahoo.co.in
Comment by kajal — October 27, 2010 @ 6:42 pm
Nice job on the articles! Since I am actually trying to do that now, is there any chance that you could also send me the source code? I am sure it would help me a lot.
Thanks
Comment by J Theonetti — December 5, 2010 @ 8:40 pm
Really great work. It would be appreciated, if you please send me the sample application for generating invoice application to my above mentioned mail id.I hope it would help me a lot. Thanks in advance.
Comment by Aparna Chanda — December 6, 2010 @ 5:57 pm
Aparna, I don’t have a sample application for invoice generation. The one that I have is for vendor read and insert. You can see its code and get help from it and write your own invoice generating app. Let me know if you’re interested in that, I’ll forward the code to you 🙂
Comment by Mukarram Mukhtar — December 6, 2010 @ 6:08 pm
Thanks for the provided information. Can you please send the code files to the below id ?
kabilan.vk@proteam.in
Regards
Kabilan
Comment by KABILAN — December 27, 2010 @ 6:47 am
Hi,
Very useful article. Your explanation for everything is also very good.
I would really appreciate if you could send me the source code.
My email address is: aarti.rukari@gmail.com and aartirukari82@yahoo.com
Many Thanks
Comment by Arti — January 6, 2011 @ 4:57 am
I would like to appreciate your great work, i think this is the only place in internet where i can get this kind of information, can you please send me the code files, am trying to read data from a quick book file and save it to a Mysql database.
Comment by Abdul Fayas — January 24, 2011 @ 7:00 am
Can you plesae send me the zip files to this id, fayas@ymail.com
Comment by Abdul Fayas — January 24, 2011 @ 7:02 am
Great Articles 1 and 2 – I have found them most instructive, would you please send me the code so i can explore further.
Thanks in Advance
Comment by Powder Bird — February 27, 2011 @ 8:07 am
It’s the resource that I was looking for, great job.
I would really appreciate if you could send me the source code.
Here is my email address : transcore_e@hotmail.com
Regards,
Transcore
Comment by Transcore — March 16, 2011 @ 2:02 am
Job well done…I have a similar requirement now…appreciate if you could send me the source code.
Thanks
Comment by Pranay — April 26, 2011 @ 3:19 pm
Very useful article and nice Explanation given by you. I just want to ask you that this code is applicable for only desktop application or can we use it for web application.(ASP.Net Application)
Thanks and Regards,
Dipti Chalke
Comment by Dipti Chalke — May 18, 2011 @ 10:52 am
In the start my team and I tried doing it as an ASP.NET web application but we were having troubles. Maybe it was lack of knowledge at that time, but due to very tight deadline we dropped that idea at pretty early stage and decided to do it as a windows app. Having said that, I would encourage you that if time permits try it in web app and share your findings with us here 🙂
Comment by Mukarram Mukhtar — May 18, 2011 @ 2:08 pm
Sir,
If we need to work with the asp.net with quickbook,Would the asp.net web application also communicate with the .qbw file or it has to communicate with the Quickbook Online edition ? Desperately waiting for your reply..
Comment by Sumit — August 4, 2011 @ 10:00 am
Hello. I have been following both your tutorials on connecting to quickbooks. It’s been very helpful, but i seem to be missing some method definitions. Could you provide the source code? Thank you
Comment by Luis — May 26, 2011 @ 8:23 pm
This is great stuff, can you send me a copy of this code. I need to link a POS with quickbooks. diras.beats@gmail.com
Comment by Ras Demina — June 5, 2011 @ 6:30 am
Thank you for your time and knowledge.
It is always good to see the work of a great programmer.
Please forward your source code. xbmnet@comcast.net
Best Regards
Comment by Henry Z — June 10, 2011 @ 9:32 pm
I have been following both your tutorials on connecting to quickbooks. Please can you send me the source code. Here is my email address thindo@yahoo.com
Comment by thindo — June 13, 2011 @ 4:10 am
hi ,
This is such a nice article.I am also developing on integration tool with Quick book .I am highly thankful to you if u send source code of this demo project.
My mail id is ashu.sajwan@gmail.com
Ashish sajwan
Comment by ashish sajwan — June 20, 2011 @ 3:33 pm
Hi,
My yahoo mail Id is ashu_cool490@yahoo.co.in
Ashish sajwan
Comment by ashish sajwan — June 20, 2011 @ 3:35 pm
hi can you send me code please to edsmith.21@gmail.com. thank you
Comment by ed — July 7, 2011 @ 8:05 pm
Hi ,
Great and neat article….
can you mail the code please….
Comment by sounthariya — August 4, 2011 @ 7:40 am
Mail your code sounthariya@proteam.in…..
Comment by sounthariya — August 4, 2011 @ 7:41 am
Hello sir,
Can you send the code for this application.I desperately need the code as i have to create one such application.
My email id is sumitthapar@hotmail.com
Thanks & Regards
Sumit
Comment by Sumit — August 4, 2011 @ 9:57 am
Hey there,
I appreciate this article. It helped. Can you send me a copy of the source code/project for this application? My email address is kyoungd@hotmail.com.
Thanks.
-Young
Comment by Young K — August 12, 2011 @ 12:33 am
Excellent articles on working with C#.Net and QB data. Would you please send me a copy of the source code? Thanks!
Comment by Leslie Van Parys — August 20, 2011 @ 9:23 pm
I have a need to integrate with quick books and would very much appreciate a copy of the source code. Thank you for your had work and willingness to share.
David
Comment by mcwdgerhartavid — August 22, 2011 @ 3:15 pm
Can you please forward the ziped project files to me as well.
Comment by Mama — August 31, 2011 @ 10:07 am
Could you pls. send me a code at rohit421991@hotmail.com.
I tried to run my intuit Quick book Application in Microsoft Visual studio 2010 using C# but it gives me error
An error requires the application to close:
Logging File: CRITICAL
Log File: c:\ProgramData\Intuit\QBSDK\log\MyTestApplicationLog.txt
Exception Caught:
Cannot create QBXMLRP2 COM component.
Comment by Rohit Kesharwani — September 9, 2011 @ 11:37 am
Source code is on its way 🙂
Comment by Mukarram Mukhtar — September 9, 2011 @ 2:01 pm
This was an amazing article…a great help. Could you send me the source code?
p2lundquist@hotmail.com
Comment by Phillip Lundquist — October 31, 2011 @ 9:02 pm
Really, very important and useful article for a developer. i appreciate your work.
Please send the code on given email id.
ranvir.singh@livialegal.com
ranvirsen@rediffmail.com
Thanks.
Regards,
Ranvir
Comment by Ranvir — November 24, 2011 @ 2:34 pm
Great Work You have done but i am not still getting connected to quick book where to add those reference files and namespaces to the application and i am working on quick book 2011-12 ore edition will this code work with that version or not.could you pls mail me the source code for help.
my email id is
anuj.thakur57@gmail.com
Anuj Thakur
thanks
Comment by Anuj Thakur — November 30, 2011 @ 7:33 am
Really working well, i try it with quickbooks 10.0 edition to add vendor and customer entry form and it working very well.
i try it for Employee entry form but it throws an errors.
Employee could not be added successfully.
There was an error when saving a Employees list, element “”. QuickBooks error message: The name of the list element cannot be blank.
if you have Employee entry form code Please send the code on given email id.
you have solution for web based application.
ranvir.singh@livialegal.com
ranvirsen@rediffmail.com
Thanks.
Regards,
Ranvir
Comment by Ranvir — December 2, 2011 @ 12:46 pm
Great set of articles on QuickBooks integration. I would like to adapt this to a VB version if possible. Could I please have a zip of the source? Much appreciated.
timmy.stephani@gmail.com
Comment by Tim — December 4, 2011 @ 12:55 am
You mistyped your e-mail address, Tim. I’m getting the following message:
Sorry, we were unable to deliver your message to the following address.
timmy.stephani@gmail.com
Comment by Mukarram Mukhtar — December 5, 2011 @ 4:11 pm
Its very good article, could ypu pls pass the sample application source code so that can see the complete workflow.
Comment by Rvai — December 21, 2011 @ 9:14 am
may I please have this code, thanks
nguyenjg AT gmail.com
Comment by jgnguyen — December 22, 2011 @ 3:40 pm
Hi Mukarram,
I try my level best to edit the vendor entry but still i am not getting the proper solution to edit the vendor.
so can you help for it by sending the edit code on given email id.
ranvir.singh@livialegal.com
ranvirkuma@gmail.com
Regards,
Ranvir
Comment by Ranvir — December 26, 2011 @ 12:37 pm
Abe:
Can you please forward that zip file of this application
to my email. I would really appreciate for your help on this
abe@wpsconsultingservices.com
Thank you
Comment by Abe — March 20, 2012 @ 1:13 pm
Very good article. Could you please send me the source for both the: How to integrate Quick Books with .Net application
and Quickbooks (Reloaded)
Thanks
Mike H
Comment by Mike Hammers — April 9, 2012 @ 12:31 pm
Thanks for a very nice article, could you please share your project files.
Thanks,
Purna.
Comment by Purna Gaddam — April 18, 2012 @ 7:01 am
I would be interested in the source if still available. kylermw [at] gmail [dot] com
Comment by Kyler — April 20, 2012 @ 7:22 pm
Kindly send me the code for exporting data into Quickbook on raj111sharp@gmail.com Thanks, – Raj
Comment by Raj — May 3, 2012 @ 4:27 pm
Very nice article. Can you please forward that zip file of this application
to my email. I would really appreciate.
temp@dmhone.com
Thanks
Comment by Mike — July 3, 2012 @ 8:23 pm
Hi Sir,
please provide the sample code for us
my mail is vivek.pal@durlabhcomputers.com
Comment by vivekpal — July 11, 2012 @ 3:21 pm
thanks for sharing your knowledge. Could you please send me the source code to the following email. kajavatana@yahoo.co.uk
thanks in advance
Comment by kaja — August 7, 2012 @ 8:11 pm
Thanks for a very nice article. Could you please send me the source for both the: How to integrate Quick Books with .Net application
and Quick books (Reloaded)
Thank you
John B
laser3g@manx.net
Comment by John B — August 11, 2012 @ 12:27 pm
Hi,this is indeed a good article.Can you send me a copy of the source code to;
stevekaiy@gmail.com
steve@kaiynetconsulting.com
Comment by Steve Kagiri — August 15, 2012 @ 10:00 am
Very interesting and I would like to intergrate with my database. Would you also send this source code? Thank you very much.
Comment by Susette — November 2, 2012 @ 4:52 am
I too need this source code.
Please send it to me on meena01.acs@gmail.com
Thanks in advance
Comment by Meena Trivedi — November 16, 2012 @ 11:33 am
Great Work. I would love to get the source Code. Kindly mail it to hoseki210@gmail.com
Comment by Sunder — December 3, 2012 @ 6:24 pm
Very interesting articles. I am trying to integrate a different language (WInDev) with QuickBooks and I have it working EXCEPT for the authorization parts using AuthPreferences from the InterOp.QBXMLRP2 Nothing makes sense to me there. Do you have any experience with AuthPreferences? If you do I would greatly appreciate it if you would contact me. spudman at wybatap.com thank you very much.
Comment by Bob Roos — December 4, 2012 @ 1:58 am
Great articule. Could you send the source code to jmorelos@softelligence.com.mx.
Thanks!
Comment by jmorelos — December 11, 2012 @ 8:10 pm
Greetings! I’ve been reading your weblog for a while now and finally got the bravery to go ahead and give you a shout out from New Caney Texas! Just wanted to tell you keep up the good job!
Comment by Wayne — December 13, 2012 @ 11:57 pm
Hi, Can you please send the code to access QuickBooks from C# .NET app to: andreizilla@gmail.com
Thank you,
Comment by Andrei — March 27, 2013 @ 6:53 pm
Thank you for your great article. Could you send the code to me?
Comment by Paul — April 20, 2013 @ 12:11 am
hi there,
Trust all is well at your end. Well is it possible for you to share me the source code. Below is my email address
nguyennx@gmail.com
Comment by guruvn — May 8, 2013 @ 1:30 am
Awesome! can you please send me copy of code?
Thank you
Comment by Alex Kay — May 18, 2013 @ 1:38 am
Very nice article and great work. Please send code to me @ nnagasaibabu@live.com
Thanks,
Naga Sai
Comment by Naga Sai Babu — June 10, 2013 @ 12:36 pm | https://mukarrammukhtar.wordpress.com/quickbooks-with-net-reloaded/ | CC-MAIN-2019-30 | refinedweb | 6,746 | 64.3 |
CONNECTIVE HTML is a simple and thin library for creating HTML user interfaces without reliance on (and hence without overhead of) techniques such as Virtual DOM / Change Detection / etc. The idea is that with advent of reactive programming libraries such as RxJS, not only there is no longer any need these techniques, but also relying on them limits our interfaces in terms of performance and capabilities.
The main body of the work on CONNECTIVE HTML is already done and it is already usable for enthusiasts. However there still remains some work to make it widely usable and production-ready. If you are interested, checkout the project's page and contribute, as any help is much appreciated.
Discussion (2)
Looks cool!
const MyComp = ({ name }, renderer) => <div>Hellow {name}!</div>
I don't understand what is happening here ^
It looks like you're passing in the renderer, but not explicitly using it. Why/how?
<div>Hellow {name}!</div>is transpiled (by some JSX transpiler such as Typescript or Babel) to
renderer.create('div', ...). In a library like React, the equivalent would be importing global name
React(
import React from 'react';), however in CONNECTIVE HTML the decision was made to keep this factory object locally scoped to enable/encourage using context-specific renderers (such as one that scopes styles for current scope/component). | https://practicaldev-herokuapp-com.global.ssl.fastly.net/loreanvictor/looking-for-contributors-on-connective-html-ncn | CC-MAIN-2021-17 | refinedweb | 220 | 50.67 |
First of all, if you are thinking Outlook Express, just forget it. The only three ways of integrating with Outlook Express are (and this is just my guessing) by paying Microsoft a lot of money and by giving them a really good reason to why you want to do that, or by hooking in through the encryption-entry, or by creating a proper hook and hacking your way in there. I've done the hacking (due to missing funds) and it's not a pretty sight, it works but it's everything from clean.
So, this is not for Outlook Express, this is only for Outlook from Office.
Ever thought of extending Outlook to add that extra functionality that you so much wished for? Well, look no further. I will try to give you enough information so that you can do that. There are two ways to extend Outlook, one is pure ATL where the other is just about some COM-interfaces in a plain DLL. We could have discussion about what way to do it, and I'm sure there are people who prefer the ATL-version to the COM-version.
Referring to it as COM-version is wrong, well, not really, it is COM, but just for the sake of it, I'll refer to it as the Exchange-way. So why Exchange when we're talking about Outlook? It started with the old Exchange 4.0 client and Microsoft exposed a way to hook in to their mail client, and since Outlook is using the same model as Exchange, that entry point to the client has stayed and we should be grateful for that because its been tested through out all these years and it's 99.9% bug free where as the ATL-version isn't really that well tested.
I guess you've understood by now that this article isn't about the ATL-version,...
Also, I need to notify you that parts of this article are copied from MSDN, but with minor changes to allow people to actually understand what's written. Microsoft have never been really good at explaining their more complicated API's, don't know why but that's the way it is...
I've decided not to start out with code, but with some background information first, once that is covered, we will make a small addin that adds a button to a new toolbar. This addin will not cover the entire architecture, but it will not only give you an idea to what you can do with an addin, but more importantly, it will (hopefully) explain the basics so that you can continue on your own in less time than it took for me...
You need to at least know what a COM-interface is, and no, I'm not talking about that
IDispatch-derived thing that VC generates for you when you create an ATL-project, I'm talking about proper COM, the old one. You will also need to know a bit about MAPI, you don't have to be a guru, but you should at least know what it's all about. If you don't know what you just read, don't worry, you'll get enough information so that you know what you should search for.
Before I get going, when and if you want to debug your addin, select Outlook.exe to be the executable in Dev-studio.
When you want to extend Outlook, what you do is basically create a DLL, export an entry-point, register the addin with Outlook by modifying the registry. But before I start talking about how that is done, let's go through the basics of how an addin is loaded, why and when it is released.
An addin is loaded several times, every time in a different context. Now, Outlook is nice enough to pass you enough information so that you can figure out in what context you've been loaded and by simply identifying the context, you can also figure out what you can do and what you shouldn't do.
In the table above, you can see three bars (five bars in total), each bar represents a different context. Each context has a timeline where the length of the bar is the time that context is loaded.
Before we look at this, its worth mention that Outlook keeps an array of addins, and that each addin has its own map of when it wants to be loaded.
So, if we take them in the load-order.
As soon as you start Outlook, Outlook loads your addin in this context, This context is the one that last the longest, it will keep your addin loaded for as long as Outlook is running.
This context is created as soon as the user has logged on, that is selected a profile to use if multiple profiles exists, and that the user has established a session with MAPI (This could involve setting up a connection to Exchange server but that is not necessarily the case as you can configure Outlook to use Pop3 only, also referred to as Internet mail only)
This is a good place to figure out if you should continue to be loaded, an example could be that you installed your addin but you only want to be loaded in the profile X or if a certain condition is met, like if you can connect to some external resource such as a server)
This context is the context that you will fight with most of the time because this context is created for each item you open in Outlook, but not only items, it can also be a new window you open in Outlook, basically every time you see a new window popup, there is a new VIEWER-context behind it. It's up to you to synchronize your resources here since your addin is not considered as a singleton.
So, how does Outlook know when to load your addin then? The best way to explain this is to look at how you register the addin in the first place.
There are two ways of telling Outlook about your addin and that is either by using an ECF-file or through the registry. I won't describe the ECF-format because that is too long and not the purpose of this article, so open up your registry and browse to HKEY_LOCAL_MACHINE\Software\Microsoft\Exchange\Client\Extensions.
What you see here is, a list of addin's. Each entry in this list is an addin and apart from the name, the entry also tells Outlook when it wants to be loaded, what interfaces the addin implements and some quite uninteresting information (see MSDN: )
Let's take an example:
Exchange Scan - 4.0;C:\Program Files\Network Associates\VirusScan\scanemal.dll;1;11000000000000;1110000;
So, what can we see from this value? Let's break down the value to smaller pieces and I'll try to explain what they mean.
Now the first three items are not very hard to understand, so we'll look into the two items that are interesting instead.
First the context-map, the map that will tell Outlook when to load a given addin :
Next in line is the interface-map, this map tells Outlook what interfaces you implement. If you are unsure (don't know how you can be unsure to what interface you implement, but hey, who am I to judge...) you can always fill this map with 1's, Outlook will then query your base interface for all the interfaces it might need and it's up to you to give the right response to that. This map contains 9 interfaces that you decide if you want to implement (where you can map 7 of these 9) and there is 1 that is mandatory and therefore can't be put in this map.
When you add an addin to the registry, Outlook caches the majority of the settings so that you need to tell him to reload the cache. There are three ways of doing this and I usually end up doing the first and the last, that way I won't have any surprises. Maybe not very clean but it works for me.
The only problem with this is that when you install the addin, you need to have full rights of the machine (or atleast read / write rights to HKEY_LOCAL_MACHINE)
Typical code for this would be:
char szAppPath[MAX_PATH]={0}; SHGetSpecialFolderPath(NULL, szAppPath, CSIDL_LOCAL_APPDATA, FALSE); strcat(szAppPath, "\\Microsoft\\Outlook\\extend.dat");
Ok, so now you know how to register your addin and how the addin is loaded but you still don't know how Outlook loads your addin, so let's talk about that now.
Your DLL needs to export one function, just one tiny function to have your addin up and running. So what does this function look like then?
LPEXCHEXT CALLBACK ExchEntryPoint() { AFX_MANAGE_STATE(AfxGetStaticModuleState()); CMyAddin *pExt = new CMyAddin(); return pExt; }
As you can see, it's a callback that returns an instance of your addin-class. Now that doesn't really look like COM, does it? Well, it is and it is done the hard way. Outlook will actually query your object for different interfaces (see above) later on. What more can you see in this code? Well, to begin with, its a DLL that uses MFC. Now this is totally up to you if you want to use MFC or not, the addin itself doesn't require MFC, it's just me using it because I find it a lot easier to use and a lot less hard work than using AYL (MFC is Buggy, yes, I know, but this is just my personal opinion so please don't flame me for that...)
Start up your Developer Studio now and create a new project, make it a Regular DLL using MFC and call it OutlookAddin.
First of all, open OutlookAddin.cpp and create a function as follows:
LPEXCHEXT CALLBACK ExchEntryPoint() { AFX_MANAGE_STATE(AfxGetStaticModuleState()); CMyAddin *pExt = new CMyAddin(); return pExt; }
Now, open your def-file and add the exported function
ExchEntryPoint @1
Not very hard, so now we have an entry-point to the addin. Now we need to add a class, a generic one called
CMyAddin, let Dev-studio generate it for you, that way you will have it in a new pair of files.
Start by changing the class so that it derives from
IExchExt, also, add the following functions so that your class looks like this :
class CMyAddin : public IExchExt {); ULONG m_ulRefCount; // Basic COM stuff, needed to know when // it's safe to delete ourselves ULONG m_ulContext; // Member to store the current context in. };
It's worth mention that the functions
AddRef,
Release and
QueryInterface comes from the standard
IUnknown.
Now that you have the core of an addin, implementing these functions shouldn't be very hard, so let's do it: (I've skipped everything except the
Install function, for the other functions, see the source-code for this article).
STDMETHODIMP CMyAddin::Install(IExchExtCallback *lpExchangeCallback, ULONG mcontext, ULONG ulFlags) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); HRESULT hRet = S_FALSE; try { m_ulContext = mcontext; switch(m_ulContext) { case EECONTEXT_TASK: { hRet = S_OK; } break; case EECONTEXT_SESSION: { hRet = S_OK; } break; case EECONTEXT_VIEWER: { hRet = S_OK; } break; case EECONTEXT_REMOTEVIEWER: case EECONTEXT_SENDNOTEMESSAGE: case EECONTEXT_SENDPOSTMESSAGE: case EECONTEXT_SEARCHVIEWER: case EECONTEXT_ADDRBOOK: case EECONTEXT_READNOTEMESSAGE: case EECONTEXT_READPOSTMESSAGE: case EECONTEXT_READREPORTMESSAGE: case EECONTEXT_SENDRESENDMESSAGE: case EECONTEXT_PROPERTYSHEETS: case EECONTEXT_ADVANCEDCRITERIA: default: { hRet = S_FALSE; } break; }; } catch(...) { } return hRet; }
You will also need to create a new CPP-file, call it MapiDefines.cpp that looks like this. The reason for this being put in a CPP-file is that these lines should not be compiled more than once.
#include "stdafx.h" #define INITGUID #define USES_IID_IExchExt #define USES_IID_IExchExtAdvancedCriteria #define USES_IID_IExchExtAttachedFileEvents #define USES_IID_IExchExtCommands #define USES_IID_IExchExtMessageEvents #define USES_IID_IExchExtPropertySheets #define USES_IID_IExchExtSessionEvents #define USES_IID_IExchExtUserEvents #define USES_IID_IMessage #define USES_IID_IMAPIContainer #define USES_IID_IMAPIFolder #define USES_IID_IMAPITable #define USES_IID_IMAPIAdviseSink #define USES_IID_IMsgStore #define USES_IID_IMAPIForm #define USES_IID_IPersistMessage #define USES_IID_IMAPIMessageSite #define USES_IID_IMAPIViewContext #define USES_IID_IMAPIViewAdviseSink #define USES_IID_IDistList #define USES_IID_IMailUser #include <mapix.h>
You will also need to add the following includes to your stdafx.h (these files should have been installed when you installed Dev-Studio).
#include <atlbase.h> #include <mapix.h> #include <mapiutil.h> #include <mapitags.h> #include <mapiform.h> #include <initguid.h> #include <mapiguid.h> #include <exchext.h> #include <exchform.h> #include <mapidefs.h> #include <mapispi.h> #include <imessage.h> #include <ocidl.h> #pragma comment(lib,"mapi32") #pragma comment(lib,"Rpcrt4") #pragma comment(lib,"Version")
Ok, so now we have a basic extension that doesn't do anything except that it gets loaded into Outlook at startup and released when Outlook is shutdown.
Now, compile the project and sort any errors or warnings out before you go on to the next part of this article.
You will not find the includes if you are developing in Visual Studio .NET, you will need to find either the Platform SDK for MAPI or the includes from Visual Studio 6.
First, lets extend our class to add a toolbar and a button at startup. For that, we need to ask Outlook for an object called <name>. We will also need to import two DLL's that defines what the "Outlook Object Model"-objects (also referred to as OOM) look like.
// If you have Outlook 2000 installed on your machine, then use the // following lines #import "mso9.dll" #import "msoutl9.olb" // If you have Outlook 2002 installed on your machine, then use the // following lines #import "mso.dll" #import "msoutl.olb" // If you have Outlook 2003 installed on your machine, then use the // following lines #import "mso11.dll" #import "msoutl11.olb"
I have used the outlook 2000 version but it doesn't matter which version you import, (you don't have to have the version you are importing installed on your machine, it's enough to have these DLL's, but it's a lot easier to debug if you have Outlook installed...anyway, I've put the import line in my stdafx.h.
I have not included these files in the ZIP-file, you will have to locate them from your Outlook-installation folder. Apart from Copyright issues, they are big (Msox.dll is about 5.3 Mb).
One thing you have to remember is that if you are using the functionality that only exists in Outlook 2003, then obviously, that won't work in Outlook 2000, but you will still be able to run your addin as long as you don't execute that piece of code. Also, forget about this whole thing if you intend to run under Outlook 97 and Outlook 98. OOM existed back then but wasn't fully implemented. You will though be able to create a toolbar under Outlook 98 but it's not straight forward and there are no events for the buttons (among other things), so you will need to do some hacking (hook's and subclassing) if you want to detect when a button is clicked.
If you still want to be able to run this under Outlook 97 or 98, then look up the
IExchExtCommands- interface and more specifically the function
InstallCommands. (I will write more about this in another article, but only if demanded as this is not the most common thing to do these days as most users are running Outlook 2000 or later).
Before you can obtain the Outlook-object, you need to add another header-file called OutlookInterface.h in which you put the following:
#ifndef _OUTLOOKINTERFACE_H #define _OUTLOOKINTERFACE_H #if defined(WIN32) && !defined(MAC) #ifndef __IOutlookExtCallback_FWD_DEFINED__ #define __IOutlookExtCallback_FWD_DEFINED__ typedef interface IOutlookExtCallback IOutlookExtCallback; #endif /* __IOutlookExtCallback_FWD_DEFINED__ */ // Outlook defines this interface as an alternate to IExchExtCallback. #ifndef __IOutlookExtCallback_INTERFACE_DEFINED__ #define __IOutlookExtCallback_INTERFACE_DEFINED__ EXTERN_C const IID IID_IOutlookExtCallback; interface DECLSPEC_UUID("0006720D-0000-0000-C000-000000000046") IOutlookExtCallback : public IUnknown { public: virtual HRESULT STDMETHODCALLTYPE GetObject( /* [out] */ IUnknown __RPC_FAR *__RPC_FAR *ppunk) = 0; virtual HRESULT STDMETHODCALLTYPE GetOfficeCharacter( /* [out] */ void __RPC_FAR *__RPC_FAR *ppmsotfc) = 0; }; DEFINE_GUID(IID_IOutlookExtCallback, 0x0006720d, 0x0000, 0x0000, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46); #endif /* __IOutlookExtCallback_INTERFACE_DEFINED__ */ #endif // defined(WIN32) && !defined(MAC) #endif // _OUTLOOKINTERFACE_H
So, to obtain that precious Outlook-object, you would add the following to your class:
#include "OutlookInterface.h" class CMyAddin : public IExchExt { public: CMyAddin(); ~CMyAddin(); : : : HRESULT GetOutlookApp(IExchExtCallback *pmecb, Outlook::_ApplicationPtr &rOLAppPtr); Outlook::_ApplicationPtr m_OLAppPtr; };
And implement it as follows:
HRESULT CMyAddin::GetOutlookApp(IExchExtCallback *pmecb, Outlook::_ApplicationPtr &rOLAppPtr) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); try { IOutlookExtCallback *pOutlook = NULL; HRESULT hRes = pmecb->QueryInterface(IID_IOutlookExtCallback, (void **) &pOutlook); if (pOutlook) { IUnknown *pUnk = NULL; pOutlook->GetObject(&pUnk); LPDISPATCH lpMyDispatch; if (pUnk != NULL) { hRes = pUnk->QueryInterface(IID_IDispatch, (void **) &lpMyDispatch); pUnk->Release(); } if (lpMyDispatch) { OLECHAR * szApplication = L"Application"; DISPPARAMS dispparamsNoArgs = {NULL, NULL, 0, 0}; DISPID dspid; VARIANT vtResult; lpMyDispatch->GetIDsOfNames(IID_NULL, &szApplication, 1, LOCALE_SYSTEM_DEFAULT, &dspid); lpMyDispatch->Invoke(dspid, IID_NULL, LOCALE_SYSTEM_DEFAULT, DISPATCH_METHOD, &dispparamsNoArgs, &vtResult, NULL, NULL); lpMyDispatch->Release(); rOLAppPtr= vtResult.pdispVal; return S_OK; } } } catch(...) { } return S_FALSE; }
So, go back to your
Install function, and add the line in bold.
STDMETHODIMP OlemAddin::Install(IExchExtCallback *lpExchangeCallback, ULONG mcontext, ULONG ulFlags) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); HRESULT hRet = S_FALSE; try { m_ulContext = mcontext; GetOutlookApp(lpExchangeCallback, m_OLAppPtr); // <--Add this line here
Ok, so what do we have here? We have an extension, that at 'Install'-time obtains an Outlook-object.
Let's see what we can do with it now and how we can actually create a toolbar and add a button to it.
First step is to create some sort of container-class for the button(s) we are going to add, this class must be derived from
IDispatch. This class will hook in to the
IConnectionPoint of the button itself, and will that way be notified when the button is clicked. Now, this is just an example. So I won't put very much effort to make this look nice or make it very usable, I leave that to you. So, open up the file MyAddin.h and add the following between the line
#include "OutlookInterface.h" and the class
CMyAddin.
class COutlookButton : public IDispatch { public: COutlookButton(CComPtr <Office::CommandBarControl> pButton); virtual ~COutlookButton(); // IUnknown Implementation virtual HRESULT __stdcall QueryInterface(REFIID riid, void ** ppv); virtual ULONG __stdcall AddRef(void); virtual ULONG __stdcall Release(void); // Methods: // IDispatch Implementation virtual HRESULT __stdcall GetTypeInfoCount(UINT* pctinfo); virtual HRESULT __stdcall GetTypeInfo(UINT iTInfo, LCID lcid, ITypeInfo** ppTInfo); virtual HRESULT __stdcall GetIDsOfNames(REFIID riid, LPOLESTR* rgszNames, UINT cNames, LCID lcid, DISPID* rgDispId); virtual); BOOL SetupConnection(IDispatch *pDisp); void ShutDown(); DWORD m_dwCookie; CComPtr <Office::CommandBarControl> m_pButton; IConnectionPoint *m_pCP; ULONG m_cRef; };
Now, to save some space in this article, I will not put the source for that class... it's kind of long, so if you have opened up the workspace for this article, then open the file OutlookButton.cpp and I will try explain the logic.
When we create an object of this type, we pass it a button as parameter. This button will be instantiated and we will hook up to the
IConnectionPoint of that button. This is done in the constructor and in the function
SetupConnection. When the button is clicked, the function
Invoke is invoked (just couldn't resist writing that...) and then it's up to you to decide what to do. In this example, we will just display a message box to indicate that the button has been clicked.
In order to keep the code readable, we'll add a function called
InstallInterface instead of putting the code in the Install function, and the prototype looks like this :
class CMyAddin : public IExchExt { public: CMyAddin(); ~CMyAddin(); : : : HRESULT InstallInterface(IExchExtCallback *lpExchangeCallback);
The function
InstallInterface is a bit long so that you will have to look at the source for this article. I've put in some comments, enough for you to get the idea of how it works.
And all we need to do now is to call that function, and we do that from the
Install function when we are in the context
EECONTEXT_VIEWER.
STDMETHODIMP CMyAddin::Install(IExchExtCallback *lpExchangeCallback, ULONG mcontext, ULONG ulFlags) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); : : case EECONTEXT_VIEWER: { : InstallInterface(lpExchangeCallback); // <--Add this line here } break;
Now compile the whole thing and once again, sort errors (if any) out.
So, the only thing you need to do now is to register the DLL and to do this, in the sources for this article, you have a registry-file. You will need to edit that one and change the path so that it points to this DLL.
In the previous two parts, we've created a basic addin that added a toolbar, and when you clicked it, displayed a message box. So in this article, we will explore some more things you can do with an addin for Outlook. With this article, I will show you how you can log all incoming mails to a file. Not very impressive but it's only to show you some basic MAPI-operations.
If you haven't read the previous articles, then go back to them otherwise you wont understand very much of this.
First, let's extend our class to derive from
IExchExtSessionEvents. This interface only has one method, and that is
OnDelivery. This method is called for each and every mail that is delivered. There might be a slight delay from the moment they come in to that you are called, it all depends on rules and other addin's, but most of the time, you get called the split-second before the mail is actually displayed in the listview.
There is one thing that is extremely important and I can't stress enough about, and that is the return value of this function. If you look in MSDN, you can read the following:
S_OK
The extension object replaced Microsoft Exchange default behavior with its own behavior. Microsoft Exchange will consider the task handled.
S_FALSE
The extension object did nothing or added additional behavior. Microsoft Exchange will continue to call extension objects or complete the work itself.
Now, read the
S_OK again, because if you do decide to return
S_OK, consider the mail as lost unless you store the mail yourself. I'm not joking, the mail is lost if you do return
S_OK.
I think you got the message by now. So let's get going on the code.
First, extend your class so that it looks like this (add the lines in bold)
class CMyAddin : public IExchExt, IExchExtSessionEvents {); STDMETHODIMP OnDelivery(IExchExtCallback *lpExchangeCallback);
Before we implement the
OnDelivery, we need to change the method
QueryInterface. This method will be called with a
REFIID set to
IID_IExchExtSessionEvents, so we need to add some lines to handle that case correct.
Once again, add the lines in bold
STDMETHODIMP CMyAddin::QueryInterface(REFIID riid, void** ppvObj) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); *ppvObj=NULL; IUnknown* punk=NULL; if (riid == IID_IUnknown) { punk = (IExchExt*)this; } else if (riid == IID_IExchExt) { punk = (IExchExt*)this; } else if (riid == IID_IExchExtSessionEvents) { punk = (IExchExtSessionEvents*)this; } else {
We have specified in the registry that we implement the
IExchExt-interface, and also the
IExchExtSessionEvents-interface so that when Outlook loads us, he will query us for the
IExchExtSessionEvents-interface and when he does, we need to give him something back.
So, over to the
OnDelivery. Add this function as follows and remember to return
S_FALSE no matter if you handled the mail or not. It's not a return-code to indicate if your custom code worked or not. It indicates if you took care of the mail or not!
STDMETHODIMP CMyAddin::OnDelivery(IExchExtCallback *lpExchangeCallback) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); try { } catch(...) { } return S_FALSE; }
Now, what we want to do is to get a pointer to the mail, extract some information and log it to a file. So first we'll ask Outlook for the pointer by calling the method
GetObject.
STDMETHODIMP CMyAddin::OnDelivery(IExchExtCallback *lpExchangeCallback) { AFX_MANAGE_STATE(AfxGetStaticModuleState()); try { // The first thing we need to do is to obtain a pointer to the message // that just arrived. // When we do that, we also obtain a pointer to the message-store (see // it as a database) LPMESSAGE lpMessage = NULL; LPMDB lpMdb = NULL; if (SUCCEEDED(lpExchangeCallback->GetObject(&lpMdb, (LPMAPIPROP*)&lpMessage))) {
The method
GetObject returns a pointer to the message-store and the mail that just arrived. The only thing we are interested in is the mail, so just ignore the message-store-pointer.
Before we continue, let's take a look at what a message is and how the data is stored in it. A MAPI-message is nothing like a mime-message. It's a binary blob and not a text-message. The data is stored in something called tags, propertytags. You could compare this to an ini-file where you have keys and values. In this case, the keys are tags.
These tags can either be predefined by MAPI, the most common ones like the subject and the body is a predefined tag, but you can also have something called named tags. Named tags are tags that you define in which you can store data that is private. This does not mean that the data is encrypted or hidden, anyone can extract this data.
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Admin | http://www.codeproject.com/KB/COM/Outlook-addin.aspx | crawl-002 | refinedweb | 4,142 | 59.03 |
Summary: in this tutorial, you’ll learn how to parse HTML webpages and import its data into a
DataFrame.
HTML is the language of the web, created for wrapping web elements into a page.
Sometimes we want to bring a HTML table into Pandas quickly for analysis. In such cases, Pandas offer the
read_html method that can both fetch the webpage and parse HTML tables, then create a DataFrame object out of that data.
Supported URL schemes include http, ftp and file (sadly no https support). The reason for the lack of HTTPS support is because Pandas relies on lxml library to perform its HTML parsing tasks, and lxml cannot access HTTPS URLs (yet).
Install lxml
Before you can perform any operation with HTML tables, you have to install lxml first by running the following command in the terminal.
pip install lxml
If you use Anaconda, lxml is already installed, no manual action required.
Read HTML tables with Pandas
In this example, we’re going to get the FDIC Failed Bank List into Pandas for further analysis.
We will use the built-in
read_html method to fetch and parse the page.
import pandas as pd url = '' df = pd.read_html(url) df[0]
Output:
Please note that
read_html automatically look for
<table> elements inside the webpage and returns a list of DataFrames, even when there’s only one table found.
In the example above, the long DataFrame has been automatically truncated by Pandas for easier viewing. You will also see a note in the lower part of the output that says “563 rows × 7 columns”. | https://monkeybeanonline.com/pandas-read-html/ | CC-MAIN-2022-27 | refinedweb | 264 | 61.26 |
Hi,
On 2016-03-14 20:10:58 -0300, Alvaro Herrera wrote: > diff --git a/src/backend/access/transam/xlogreader.c > b/src/backend/access/transam/xlogreader.c > index fcb0872..7b60b8f 100644 > --- a/src/backend/access/transam/xlogreader.c > +++ b/src/backend/access/transam/xlogreader.c > @@ -10,9 +10,11 @@ > * > * NOTES > * See xlogreader.h for more notes on this facility. > + * > + * This file is compiled as both front-end and backend code, so it > + * may not use ereport, server-defined static variables, etc. > *------------------------------------------------------------------------- > */ > - Huh? > #include "postgres.h" > > #include "access/transam.h" > @@ -116,6 +118,11 @@ XLogReaderAllocate(XLogPageReadCB pagereadfunc, void > *private_data) > return NULL; > } > > +#ifndef FRONTEND > + /* Will be loaded on first read */ > + state->timelineHistory = NIL; > +#endif > + > return state; > } > > @@ -135,6 +142,10 @@ XLogReaderFree(XLogReaderState *state) > pfree(state->errormsg_buf); > if (state->readRecordBuf) > pfree(state->readRecordBuf); > +#ifndef FRONTEND > + if (state->timelineHistory) > + list_free_deep(state->timelineHistory); > +#endif Hm. So we don't support timelines following for frontend code, although it'd be rather helpful for pg_xlogdump. And possibly pg_rewind. > pfree(state->readBuf); > pfree(state); > } > @@ -208,10 +219,11 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr > RecPtr, char **errormsg) > > if (RecPtr == InvalidXLogRecPtr) > { > + /* No explicit start point; read the record after the one we > just read */ > RecPtr = state->EndRecPtr; > > if (state->ReadRecPtr == InvalidXLogRecPtr) > - randAccess = true; > + randAccess = true; /* allow readPageTLI to go > backwards */ randAccess is doing more than that, so I'm doubtful that comment is an improvment. > /* > * RecPtr is pointing to end+1 of the previous WAL record. If > we're > @@ -223,6 +235,8 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, > char **errormsg) > else > { > /* > + * Caller supplied a position to start at. > + * > * In this case, the passed-in record pointer should already be > * pointing to a valid record starting position. > */ > @@ -309,8 +323,10 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr > RecPtr, char **errormsg) > /* XXX: more validation should be done here */ > if (total_len < SizeOfXLogRecord) > { > - report_invalid_record(state, "invalid record length at > %X/%X", > - (uint32) > (RecPtr >> 32), (uint32) RecPtr); > + report_invalid_record(state, > + "invalid record length at > %X/%X: wanted %lu, got %u", > + (uint32) > (RecPtr >> 32), (uint32) RecPtr, > + > SizeOfXLogRecord, total_len); > goto err; > } > gotheader = false; > @@ -466,9 +482,7 @@ err: > * Invalidate the xlog page we've cached. We might read from a different > * source after failure. > */ > - state->readSegNo = 0; > - state->readOff = 0; > - state->readLen = 0; > + XLogReaderInvalCache(state); I don't think that "cache" is the right way to describe this. > #include <unistd.h> > > -#include "miscadmin.h" > - spurious change imo. > /* > - * TODO: This is duplicate code with pg_xlogdump, similar to walsender.c, but > - * we currently don't have the infrastructure (elog!) to share it. > + * Read 'count' bytes from WAL into 'buf', starting at location 'startptr' > + * in timeline 'tli'. > + * > + * Will open, and keep open, one WAL segment stored in the static file > + * descriptor 'sendFile'. This means if XLogRead is used once, there will > + * always be one descriptor left open until the process ends, but never > + * more than one. > + * > + * XXX This is very similar to pg_xlogdump's XLogDumpXLogRead and to XLogRead > + * in walsender.c but for small differences (such as lack of elog() in > + * frontend). Probably these should be merged at some point. > */ > static void > XLogRead(char *buf, TimeLineID tli, XLogRecPtr startptr, Size count) > @@ -648,8 +657,12 @@ XLogRead(char *buf, TimeLineID tli, XLogRecPtr startptr, > Size count) > XLogRecPtr recptr; > Size nbytes; > > + /* > + * Cached state across calls. > + */ One line? > static int sendFile = -1; > static XLogSegNo sendSegNo = 0; > + static TimeLineID sendTLI = 0; > static uint32 sendOff = 0; > > p = buf; > @@ -664,11 +677,12 @@ XLogRead(char *buf, TimeLineID tli, XLogRecPtr > startptr, Size count) > > startoff = recptr % XLogSegSize; > > - if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo)) > + /* Do we need to open a new xlog segment? */ > + if (sendFile < 0 || !XLByteInSeg(recptr, sendSegNo) || > + sendTLI != tli) > { s/open a new/open a different/? New imo has connotations that we don't really want here. > char path[MAXPGPATH]; > > - /* Switch to another logfile segment */ > if (sendFile >= 0) > close(sendFile); E.g. you could just have moved the above comment. > /* Need to seek in the file? */ > if (sendOff != startoff) > { > if (lseek(sendFile, (off_t) startoff, SEEK_SET) < 0) > - { > - char path[MAXPGPATH]; > - > - XLogFilePath(path, tli, sendSegNo); > - > ereport(ERROR, > (errcode_for_file_access(), > errmsg("could not seek in log segment %s to > offset %u: %m", > - path, startoff))); > - } > + XLogFileNameP(tli, sendSegNo), > startoff))); > sendOff = startoff; > } Not a serious issue, more a general remark: I'm doubtful that going for palloc in error situations is good practice. This will be allocated in the current memory context; without access to the emergency error reserves. I'm also getting the feeling that the patch is bordering on doing some relatively random cleanups mixed in with architectural changes. Makes things a bit harder to review. > +static void > +XLogReadDetermineTimeline(XLogReaderState *state) > +{ > + /* Read the history on first time through */ > + if (state->timelineHistory == NIL) > + state->timelineHistory = readTimeLineHistory(ThisTimeLineID); > + > + /* > + * Are we reading the record immediately following the one we read last > + * time? If not, then don't use the cached timeline info. > + */ > + if (state->currRecPtr != state->EndRecPtr) > + { > + state->currTLI = 0; > + state->currTLIValidUntil = InvalidXLogRecPtr; > + } Hm. So we grow essentially a second version of the last end position and the randAccess stuff in XLogReadRecord(). > + if (state->currTLI == 0) > + { > + /* > + * Something changed; work out what timeline this record is on. > We > + * might read it from the segment on this TLI or, if the > segment is > + * also contained by newer timelines, the copy from a newer TLI. > + */ > + state->currTLI = tliOfPointInHistory(state->currRecPtr, > + > state->timelineHistory); > + > + /* > + * Look for the most recent timeline that's on the same xlog > segment > + * as this record, since that's the only one we can assume is > still > + * readable. > + */ > + while (state->currTLI != ThisTimeLineID && > + state->currTLIValidUntil == InvalidXLogRecPtr) > + { > + XLogRecPtr tliSwitch; > + TimeLineID nextTLI; > + > + tliSwitch = tliSwitchPoint(state->currTLI, > state->timelineHistory, > + > &nextTLI); > + > + /* round ValidUntil down to start of seg containing the > switch */ > + state->currTLIValidUntil = > + ((tliSwitch / XLogSegSize) * XLogSegSize); > + > + if (state->currRecPtr >= state->currTLIValidUntil) > + { > + /* > + * The new currTLI ends on this WAL segment so > check the next > + * TLI to see if it's the last one on the > segment. > + * > + * If that's the current TLI we'll stop > searching. I don't really understand how we're stopping searching here? > + */ > + state->currTLI = nextTLI; > + state->currTLIValidUntil = InvalidXLogRecPtr; > + } > + } > +} XLogReadDetermineTimeline() doesn't sit quite right with me, I do wonder whether there's not a simpler way to write this. > +/* > + * XLogPageReadCB callback for reading local xlog files > * > * Public because it would likely be very helpful for someone writing another > * output method outside walsender, e.g. in a bgworker. > * > - * TODO: The walsender has it's own version of this, but it relies on the > + * TODO: The walsender has its own version of this, but it relies on the > * walsender's latch being set whenever WAL is flushed. No such > infrastructure > * exists for normal backends, so we have to do a check/sleep/repeat style of > * loop for now. > @@ -754,46 +897,88 @@ int > read_local_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, > int reqLen, XLogRecPtr targetRecPtr, char *cur_page, TimeLineID > *pageTLI) > { > - XLogRecPtr flushptr, > + XLogRecPtr read_upto, > loc; > int count; > > loc = targetPagePtr + reqLen; > + > + /* Make sure enough xlog is available... */ > while (1) > { > /* > - * TODO: we're going to have to do something more intelligent > about > - * timelines on standbys. Use readTimeLineHistory() and > - * tliOfPointInHistory() to get the proper LSN? For now we'll > catch > - * that case earlier, but the code and TODO is left in here for > when > - * that changes. > + * Check which timeline to get the record from. > + * > + * We have to do it each time through the loop because if we're > in > + * recovery as a cascading standby, the current timeline > might've > + * become historical. > */ > - if (!RecoveryInProgress()) > + XLogReadDetermineTimeline(state); > + > + if (state->currTLI == ThisTimeLineID) > { > - *pageTLI = ThisTimeLineID; > - flushptr = GetFlushRecPtr(); > + /* > + * We're reading from the current timeline so we might > have to > + * wait for the desired record to be generated (or, for > a standby, > + * received & replayed) > + */ > + if (!RecoveryInProgress()) > + { > + *pageTLI = ThisTimeLineID; > + read_upto = GetFlushRecPtr(); > + } > + else > + read_upto = GetXLogReplayRecPtr(pageTLI); > + > + if (loc <= read_upto) > + break; > + > + CHECK_FOR_INTERRUPTS(); > + pg_usleep(1000L); > } > else > - flushptr = GetXLogReplayRecPtr(pageTLI); > + { > + /* > + * We're on a historical timeline, so limit reading to > the switch > + * point where we moved to the next timeline. > + */ > + read_upto = state->currTLIValidUntil; Hm. Is it ok to not check GetFlushRecPtr/GetXLogReplayRecPtr() here? If so, how come? > - if (loc <= flushptr) > + /* > + * Setting pageTLI to our wanted record's TLI is > slightly wrong; > + * the page might begin on an older timeline if it > contains a > + * timeline switch, since its xlog segment will have > been copied > + * from the prior timeline. This is pretty harmless > though, as > + * nothing cares so long as the timeline doesn't go > backwards. We > + * should read the page header instead; FIXME someday. > + */ > + *pageTLI = state->currTLI; > + > + /* No need to wait on a historical timeline */ > break; > - > - CHECK_FOR_INTERRUPTS(); > - pg_usleep(1000L); > + } > } > > - /* more than one block available */ > - if (targetPagePtr + XLOG_BLCKSZ <= flushptr) > + if (targetPagePtr + XLOG_BLCKSZ <= read_upto) > + { > + /* > + * more than one block available; read only that block, have > caller > + * come back if they need more. > + */ > count = XLOG_BLCKSZ; > - /* not enough data there */ > - else if (targetPagePtr + reqLen > flushptr) > + } > + else if (targetPagePtr + reqLen > read_upto) > + { > + /* not enough data there */ > return -1; > - /* part of the page available */ > + } > else > - count = flushptr - targetPagePtr; > + { > + /* enough bytes available to satisfy the request */ > + count = read_upto - targetPagePtr; > + } > > - XLogRead(cur_page, *pageTLI, targetPagePtr, XLOG_BLCKSZ); > + XLogRead(cur_page, *pageTLI, targetPagePtr, count); When are we reading less than a page? That should afaik never be required. > + /* > + * We start reading xlog from the restart lsn, even though in > + * CreateDecodingContext we set the snapshot builder up using > the > + * slot's candidate_restart_lsn. This means we might read xlog > we > + * don't actually decode rows from, but the snapshot builder > might > + * need it to get to a consistent point. The point we start > returning > + * data to *users* at is the candidate restart lsn from the > decoding > + * context. > + */ Uh? Where are we using candidate_restart_lsn that way? I seriously doubt it is - candidate_restart_lsn is about a potential future restart_lsn, which we can set once we get reception confirmation from the client. > @@ -299,6 +312,18 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo > fcinfo, bool confirm, bool bin > CHECK_FOR_INTERRUPTS(); > } > > + /* Make sure timeline lookups use the start of the next record > */ > + startptr = ctx->reader->EndRecPtr; Huh? startptr isn't used after this, so I'm not sure what this even means? > + /* > + * The XLogReader will read a page past the valid end of WAL > because > + * it doesn't know about timelines. When we switch timelines > and ask > + * it for the first page on the new timeline it will think it > has it > + * cached, but it'll have the old partial page and say it can't > find > + * the next record. So flush the cache. > + */ > + XLogReaderInvalCache(ctx->reader); > + dito. > diff --git a/src/test/modules/decoding_failover/decoding_failover.c > b/src/test/modules/decoding_failover/decoding_failover.c > new file mode 100644 > index 0000000..669e6c4 > --- /dev/null > +++ b/src/test/modules/decoding_failover/decoding_failover.c > + > +/* > + * Create a new logical slot, with invalid LSN and xid, directly. This does > not > + * use the snapshot builder or logical decoding machinery. It's only intended > + * for creating a slot on a replica that mirrors the state of a slot on an > + * upstream master. > + * > + * You should immediately decoding_failover_advance_logical_slot(...) it > + * after creation. > + */ Uh. I doubt we want this, even if it's formally located in src/test/modules. These comments make it appear not to be only intended for that, and I have serious doubts about the validity of the concept as is. This seems to need some more polishing. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: | https://www.mail-archive.com/pgsql-hackers@postgresql.org/msg281579.html | CC-MAIN-2018-51 | refinedweb | 1,832 | 54.52 |
Welcome to the Dependency Injection article series. In this series we are explaining various techniques to implement Dependency Injection. In our previous article we saw how to implement Dependency Injection using the constructor injection technique. You can read it here.Understand Dependency Injection: Constructor Injection.In this article we will learn how to implement Dependency Injection using Property Injection. We explained in the previous article how Dependency Injection helps to implement a de-coupled architecture. In this article we will not repeat them, rather we will explain the implementation part directly.The basic idea of Dependency Injection is to reduce the dependency of one component on another. For example, consider that one server class and another client class exists, if they talk directly then we can say that they are tightly coupled but if they communicate via an interface then we can say that they are loosely couple. The scenario is like the following.In this picture we see that the consumer class is not talking to the service class directly. The Caller interface is the connection between them. So, now if we change any implementation of the Service class then it will not affect the Consumer class. Try to understand the following example.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;
namespace Client
{
public interface ICaller
{
void Serve();
}
public class Service : ICaller
public void Serve()
{
Console.WriteLine("Service Started");
}
public class Client
private ICaller s;
public ICaller CallService
set
{
this.s = value;
}
public void Start()
Console.WriteLine("Service is called by client");
this.s.Serve();
class Program
static void Main(string[] args)
//Create object of client Class
Client c = new Client();
//Create object of service class using ICaller interface
ICaller ic = new Service();
//Set property of client class
//Thsi is the main trick. It will define which function need to call
c.CallService = ic;
//Call to service
c.Start();
Console.ReadLine();
}Here is sample output.The example above is very simple to understand. In the client class we are setting the object of the service class to the CallService property. When we call the Start() method from the Main() function the appropriate Service() method is being called that is defined in the Service class.ConclusionIn this example we have learned how to implement the Dependency Injection architectural style using the Property Injection technique. Hope you have understood the concept. In the next article we will learn to implement Dependency Injection using the Function Injection technique. Happy learning.
View All | http://www.c-sharpcorner.com/UploadFile/dacca2/understand-dependency-injection-property-injection/ | CC-MAIN-2017-51 | refinedweb | 417 | 50.94 |
audio_engine_channels(9E)
audio_engine_playahead(9E)
- read data from a device
#include <sys/types.h> #include <sys/errno.h> #include <sys/open.h> #include <sys/uio.h> #include <sys/cred.h> #include <sys/ddi.h> #include <sys/sunddi.h> int prefixread.
The driver read() routine is called indirectly through cb_ops(9S) by the read(2) system call. The read() routine should check the validity of the minor number component of dev and the user credential structure pointed to by cred_p (if pertinent). The read() routine should supervise the data transfer into the user space described by the uio(9S) structure.
The read() routine should return 0 for success, or the appropriate error number.
Example 1 read() routine using physio()
The following is an example of a read() routine using physio(9F) to perform reads from a non-seekable device:
static int xxread(dev_t dev, struct uio *uiop, cred_t *credp) { int rval; offset_t off; int instance; xx_t xx; instance = getminor(dev); xx = ddi_get_soft_state(xxstate, instance); if (xx == NULL) return (ENXIO); off = uiop->uio_loffset; rval = physio(xxstrategy, NULL, dev, B_READ, xxmin, uiop); uiop->uio_loffset = off; return (rval); }
read(2), write(9E), physio(9F), cb_ops(9S), uio(9S) | http://docs.oracle.com/cd/E23824_01/html/821-1476/read-9e.html | CC-MAIN-2015-14 | refinedweb | 193 | 58.89 |
I just downloaded a kde4 program and tried to run cmake to compile. Got this love note: CMake Error at /usr/share/kde4/apps/cmake/modules/FindKDE4Internal.cmake:355 (MESSAGE): NOTE from Debian KDE maintainers: You can not upload KDE 4.2 based packages to Debian unstable yet. I am not really doing anything of the kind, I don't think. Certainly libraries, probably the package including this, are on Sid. All else remains on experimental. I commented out the #if --> #endif involved here and cmake now runs successfully. The compilation can proceed. If I am missing any dependencies, that is my problem. | http://lists.debian.org/debian-kde/2009/03/msg00091.html | CC-MAIN-2013-48 | refinedweb | 103 | 62.04 |
C9 Lectures: Stephan T. Lavavej - Standard Template Library (STL), 8 of n
- Posted: Nov 17, 2010 at 7:19AM
- 96,146 views
- 36 8, Stephan guides us on a journey into the dense forest of Regular Expressions. from STL
!
While I wait for part 9, I'll dig a couple of places in my existing code base for regex replacements
(but, please, don't let me waiting for too long!)
Thank you so much for the content!
9 is coming next week.Stephan recorded 8 and 9 on the same day, so there is no excuse for 9 not posting next week. I'm to blame if it doesn't!
C
Yeah!!
GOOD!!
Thank you, Charles.
Great Lecture and video.
This episode is interesting.
Thanks alot, Stephan!!
thumb up !!
EXCELLENT! Love these. Please keep 'em coming.
Thanks!!!
I downloaded the high quality MP4, and the audio is a few seconds ahead of the video. Anyone else seeing this?
If I match the regular expression "a+" against a sequence of "a" characters, how does the regex determine how many "a" characters to choose? Is there something like a "maximum munch rule" for regular expressions?
@NotFredSafe:If the regex is greedy (default), as many characters as possible are matched. It is explained in the PPT document on page 16.
Great lecture series, thank you.
My question is really about lecture #1 -- I posted this question at the page for lecture # 1 originally: Why does the DOS screen pop up during your Visual Studio builds? I use VS 2010 and my installation does not do this. Thanks again -
Todd
Awesome! Thank you for this video!
[quote]
6 hours ago, Toddintr wrote
Great lecture series, thank you.
My question is really about lecture #1 -- I posted this question at the page for lecture # 1 originally: Why does the DOS screen pop up during your Visual Studio builds? I use VS 2010 and my installation does not do this. Thanks again -
Todd
[/quote]
STL is putting a breakpoint on the last line and is running in debug mode in most videos. This causes his programs to break before closing.
[NotFredSafe]
> If I match the regular expression "a+" against a sequence of "a" characters,
> how does the regex determine how many "a" characters to choose? Is there
> something like a "maximum munch rule" for regular expressions?
[Vaclav]
> @NotFredSafe:If the regex is greedy (default), as many characters as
> possible are matched. It is explained in the PPT document on page 16.
Slight correction: greediness is a property of individual quantifiers, not whole regexes. A regex can contain both greedy quantifiers and non-greedy quantifiers:
Greedy quantifiers want to consume as many characters as possible, while still allowing the regex to match the string (regex_match() versus regex_search() determines whether the whole regex must match the whole string, or just a substring).
Non-greedy quantifiers want to consume as few characters as possible, while still allowing the regex to match the string.
In the example above, ([0-9]+) is greedy, so it'll consume 123456 and two of the 1701s. It can't eat the third, though, because ((?:1701)+) comes next and wants to eat at least one 1701. (This might be confusing because two greedy quantifiers, ([0-9]+) and ((?:1701)+), appear next to each other. You can think of the regex as being matched left to right, so ([0-9]+) comes first and gets to decide what it's going to do. It'll satisfy its own preferences, while being aware of whether the rest of the regex will match the rest of the string.)
Because ([0-9]+?) is non-greedy, it wants to eat as few digits as possible. Ideally, it'd like to eat just the 6. However, that would leave 54321172917291729ghi for ((?:1729)+)ghi to match, which wouldn't work. Therefore, the ([0-9]+?) consumes 654321, and leaves all three 1729s for ((?:1729)+) to eat.
[Toddintr]
> Why does the DOS screen pop up during your Visual Studio builds?
I'm building console programs, so when I compile-and-execute them, the Command Prompt appears. If I were building graphical programs, their GUIs would appear.
I usually run the compiler from the Command Prompt, as in the example above (if you haven't seen this, Start > All Programs > Microsoft Visual Studio 2010 > Visual Studio Tools > Visual Studio Command Prompt (2010) will launch a Command Prompt where you can run cl.exe, the compiler). But I use the Visual Studio IDE in the videos because most people are familiar with that.
@Stephan: thanks for another brilliant lecture.
@Charles: more than three weeks of post-production and no special effects? Not even a lens flare?
Anyway, thank you guys. You've got to love Channel9.
Wouldn't it make sense to link to the PPT above?
I've uploaded my slides to my SkyDrive:
[quote]
Nov 17, 2010 at 1:26 PM, Charles wrote
9 is coming next week.Stephan recorded 8 and 9 on the same day, so there is no excuse for 9 not posting next week. I'm to blame if it doesn't![/quote]
So it's friday, time is up and oh <sarcasm> surprise </sarcasm> Charles failedi saw that coming.Charles, predicable much ?yes Charles there is still time (time zones, sigh) but i couldnt resist being early with the blaming and hating <sarcasm> since i love microsoft employees so much </sarcasm>
well we all have to have a hobby right ? Oh who am i kidding microsoft deserves it :3
Stephan T. Lavavej is an exception of course to the above, love you!
[/quote]
Hoildays changed the plan. Next week!
C
@Charles:So you're not the sharpest one when it comes to planing then, shouldnt you be good at that in your job, anyway, oh well could happen to all of us, although shouldnt you have seen this holidays coming since it's every year at the same date ?
So Mei, would you like some cheese with that whine?
@NotFredSafe: Sure, can i have some biscuits too ?
Note: I was just pointing out the obvious flaws in Charles excuse.What's next excuse ?"Sorry, santa claus came at Christmas so i couldn't ..." "Sorry, the dog ate my to do list"
"Sorry, a butterfly died at the other side of the planet so i couldn't ..."Do i get more cheese now ? with biscuits ? and some tea too ? ooo yummy...
Hi Stephan,
Another great lecture. I was working with boost::regex and didn't know tr1 has it already. I found the interface similar to boost::regex, so i wanted to know if tr1 regex is adopted from boost and i should expect similar interface?
Thanks,
Vikas.
Part 9:
[Vikas]
> i wanted to know if tr1 regex is adopted from boost
Yep, TR1/C++0x <regex> was based on Boost.Regex.
> and i should expect similar interface?
Their interfaces are virtually identical. The biggest differences are in their regular expression grammars. std::regex uses ECMAScript 3's grammar, which was derived from Perl's. boost::regex supports those features, but has recently implemented even more advanced features from Perl (e.g. possessive quantifiers).
Hello,
I am replacing the key_compare() with cmp function in a set
std::set<
long,mycmp<long> >s;
mycmp<long >* p=&s.key_comp();
It looks like this STL version creates a class copy, so the copied class members are hard to reach. p points to the original class instance.
I am not able to find info on how to:
a/Prevent STL copiing the class, so it works with the original.
b/Locate description of some established method to comunicate with the copied class data members.
Thanks Jan
What exactly are you trying to do with the comparator?
@STL:Hello, thanks for quick response!
and for excellent lessons on STL! Without the lessons, I'd awoid STL...
To drill it down to essentials. I'm trying to do what I used to do with quicksort and its callback. I am aware this is -probably- not intended use of STL. I have a lot of strings I have to sort, or rather, I do not want to sort in a set. I'm putting the strings( counted in 1000+) in a vector, numberig them by arrival as en index in the vector, which I sort in a set. Sacrificing some ram, things used to run much faster that way. In the set<long>'s key_compare, I'm comparing strings. I even use set.find to exclude doublets. That means I need 2 ways of comparing strings, one for set.find and another one for set.insert.
In addition, I wish I could hide a lot of data members. Recently, I'm forced to use static/global data(Hm...) So forget about easy concurrency...
Otherwise, the code works.
// compile with: /EHsc#include <stdafx.h>#include <ppl.h>#include <iostream>#include<set>#include<vector>#include<string>#include<algorithm>#include<functional>using std::binary_function;
// the class data members are temporarily referenced as globals because I experience key_comp() // class data member access problems.
// there is one code, so DBG tracks key_comp(), 2 data members sets
// in addition to constructor, operator () adresses the copy as well
std::vector<std::string> v;
// instead of sorting strings, put them in an unsorted // vector and sort corresponding vector indexes in a set// Pros: On most architectures it will outperform string sort.// Cons: extra memory allocation of index values//template<class T> class cmp;// compiles OK without declarationstemplate<class T> class cmp{public:
// forced to global residence#if 0 int st,mxi; std::string stl;#endif cmp(){}; //~cmp();// linker error bool operator () (const T& t1,const T& t2)const{ switch(st){ case 0:// sort vector arrival indexes in a set return v.at(t1)<v.at(t2); case 1:// find index of the string, mxi is max index value+1,not present in the set if (t1==mxi)return stl<v.at(t2); return v.at(t1)<stl; default: // the program is sick
std::cout<<"program error: st,mxi,stl="<<st<<" "<<mxi<<" "<<stl<<std::endl; terminate(); ; }//sw }//op};
Another piece of code:
const std::string str[10]={"1","9","8","6","5","1","9","3","2","1"}; int maxind=0; std::cout<<std::endl<<"Input:"<<std::endl; for(int i=0;i<10;i++){ std::cout<<str[i]<<" "; // find str st=1;mxi=maxind;stl=str[i];if(s.find(maxind)!=s.end())continue;// found v.push_back(str[i]);// not found st=0; s.insert(maxind);maxind++; }
std::cout<<std::endl<<"Output:"<<std::endl; for_each( s.begin(),s.end(),prn); std::cout<<std::endl; // How?? [](int n){std::cout<<std::endl<<v.at(n);} s.clear(); v.clear(); //____________________ std::set<long,cmpo<long> >s1; cmpo<long>* p1=&s1.key_comp();
Thanks Jan
Are you saying that your ultimate goal is to sort a sequence of strings? With VC10, just use sort() on vector<string>. Move semantics will automatically avoid unnecessary dynamic memory allocation/deallocation during the sort.
Here's VC10 sorting 170,000 strings occupying 10 MB in 106 ms on my Q9450:
Attempting to sort the strings indirectly is even slower:
Using set is even worse (#include <set> above):
Hello,
Please, You have not answered my question: how do I access data members of my set's class key_compare() in STL ?
I will not only sort, I will remove about 80% of redundant info, using set.find.
Using a vector, I am out of memory on the destination computer, which will not be upgraded.
Using a set, things will work.
Thanks for taking Your time for the comparations!
Sorting strings of a vector can make life easier later on in an application, so its good thing to optimize it.
The comparations:
Q9450, what an impressing speed! With that power, I would test every case building the containers from scratch for every case, thus re-reading the string file or the like.
a/You do not add the time to build up the first vector, and the build up of the other containers may take longer than You think. It may be missleading.
b/You sort it, and then feed it(sorted) to the pointer and set versions. The sort times can not be compared, its different data. Some sort versions do not like sorted data.
c/ For the vector, You prealocate the final space, but not for the set.
But anyway, the pointer and set versions can be somehow compared. I expect the set perfom worse, it has to rebuild the tree for every new item. But in my app, from the pointer vector version, I would have to compare 100% and delete about 80% of the items, which is already done in the set version. So I expect both methods take about the same time for my app.
Thanks Jan
> You have not answered my question: how do I access data members of my set's class key_compare() in STL ?
That's because I'm trying to understand and solve the overall problem. From what I've seen so far, your current approach is not ideal.
> I will not only sort, I will remove about 80% of redundant info, using set.find.
Ah, you're saying that the data isn't in memory to begin with. In that case, why not use set<string>?
Additionally, set::insert automatically avoids inserting duplicate elements. Calling set::find before set::insert performs *two* lookups instead of one!
> Q9450, what an impressing speed!
It was fast in 2008. I'd call it average for a dev machine now.
> With that power, I would test every case building the containers from scratch for every case, thus re-reading the string file or the like.
Oh, I presented my code in what appears to be a slightly misleading manner in an attempt to save space. The snippets beginning with "const long long start = counter();" are intended to entirely replace the bottom of the original program beginning with that line, forming three independent programs. I believed that this was clear but if it wasn't, I apologize.
> a/You do not add the time to build up the first vector
That was intentional. My understanding at the time was that the data was already in memory.
> b/You sort it, and then feed it(sorted) to the pointer and set versions. The sort times can not be compared, its different data. Some sort versions do not like sorted data.
This was not the case - see above.
> c/ For the vector, You prealocate the final space, but not for the set.
Again, I assumed that the data was already in memory.
(This is why *extremely clear* problem descriptions are vital.)
set<string> should outperform set<const string *, comparator> above due to reduced indirection (but I expect the difference to be slight).
However, there is a performance bug in VC10 RTM that you should be aware of. When inserting lots of duplicate data into a set (which is your scenario), VC10 RTM can perform unnecessary allocations and deallocations which significantly harm performance. (The code allocates a node, tries to insert it in the set, notices that it's a duplicate, and then deallocates the node.) When you insert *const lvalues*, the unnecessary work is avoided. So, T t; s.insert(t); triggers the slow codepath, but s.insert(static_cast<const T&>(t)); triggers the fast codepath.
This problem has been thoroughly fixed in VC11.
Hello,
I understand You are wondering why I use two containers. It will be compared to another software, which is designed that way. This is the only way to sort strings in that design. Its fast, but wery limited and very, very inconvenient to work with. I think it will be abandoned, regardless of STL performance. Later, I will change STL approach to more simple, one container design, for this gentleman who wants it this way. I already did in other simple projects for myself and others, in fact. I have not experienced any STL introduced troubles at all. But my STL experience and knowlege is still very limited.
It is a strange "double container" design that caused me strange troubles.
So thanks on performance hints, if that is so easy to do so why not do it.
I do not expect top performance from STL in this early release, there are so many other countless reasons to use it. Dot.
In a post marked now 4 days ago I posted a small test of "double container software" to show it works with globals. You see if I find an item already in the set, it will not insert it.
If I could not design set.find in few minutes, I would not. I heard other peple discovered the node behavior by insert, but it cannot hart performace significantly I believe.
Now, I can see while debugging, there is a copy of my key_comp class data somewhere.
I understand I have to implement a copy constructor and get a pointer to and work with the copy. But I do not know why the copy is implemented, so I wonder if there is something more I have to do.
Thanks Jan
Hi Stephan,
Awesome video series. Looking forward to the next parts.
One question: Qt's regex engine allows to determine whether a given string is a prefix of something that could match a regex, e.g. for the regext a+b+, it would recognize that "aaaaa" is a valid prefix. This is very useful for validating user input as it comes in. Is there a way to make the std regex engine do this?
On a side note, if you use Start Without Debugging (Ctrl+F5) to start programs, VS will insert keep the console open, so you don't need a dummy line with a breakpoint.
> Is there a way to make the std regex engine do this?
std::regex can't, but boost::regex can. See
Hello,
class set with replaced functor comparator is a frenetic copier of key_comp object.
It creates 3 copies to begin with, later it copies copy #2 to copy #3 at every acess
of its functions. Of course its possible to callback from a class copy creator, but a function using global control variables is maybe better.
Questions:
Is there any rational explanation of the software's behavior?
It is claimed functor object adds a "state". What does that mean in these circumstances?
Thanks Jan
Thank you very much Stephan for such a nice series of STL ;)! I love your talk ^_^
How does the regex implementation compare to RE2?
If I understood correctly Stephan said DO NOT loop incrementally through smatch m[i] results. Would the following code work in context?:
static int i;
if(regex_match(s,m,r))
{
while(i <= m.size())
return foo( m[++i], pf);
}
really talking with this Guy on STL is twice as valuable as reading four books on stl . awesome and looking for a presentation like this on MFC. the presentation is not simply about programming but it include scientific computation which helps understand what is under the hood.
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Remove this threadClose | https://channel9.msdn.com/Series/C9-Lectures-Stephan-T-Lavavej-Standard-Template-Library-STL-/C9-Lectures-Stephan-T-Lavavej-Standard-Template-Library-STL-8-of-n?format=smooth | CC-MAIN-2015-48 | refinedweb | 3,188 | 75 |
Serial
Serial is a generic protocol used by computers and electronic modules to send and receive control information and data. The Serial link has two unidirection channels, one for sending and one for receiving. The link is asynchronous, and so both ends of the serial link must be configured to use the same settings.
One of the Serial connections goes via the mbed USB port, allowing you to easily communicate with your host PC.
Hello World!¶
Import program
API¶
API summary
Interface¶
The Serial Interface can be used on supported pins and USBTX/USBRX
Note that USBTX/USBRX are not DIP pins; they represent the pins that route to the interface USB Serial port so you can communicate with a host PC.
Note
If you want to send data to a host PC, take a look at:
Note that on a windows machine, you will need to install a USB Serial driver, see:
Serial channels have a number of configurable parameters:
- Baud Rate - There are a number of standard baud rates ranging from a few hundred bits per seconds, - An optional parity bit can be added. The parity bit will be automatically set to make the number of 1's in the data either odd or even. Parity settings are Odd, Even or None. The default setting for a Serial connection on the mbed microcontroller is for the parity to be set to None.
- Stop Bits - After data and parity bits have been transmitted, 1 or 2 stop bit is inserted to "frame" the data. The default setting for a Serial connection on the mbed microcontroller is for one stop bit to be added.
The default settings for the mbed microcontroller are described as 9600 8N1, and this is common notation for Serial port settings.
See Also¶
Reference¶
Examples¶
Write a message to a device at a 19200 baud
#include "mbed.h" Serial device(p9, p10); // tx, rx int main() { device.baud(19200); device.printf("Hello World\n"); }
Provide a serial pass-through between the PC and an external UART
#include "mbed.h" Serial pc(USBTX, USBRX); // tx, rx Serial device(p9, p10); // tx, rx int main() { while(1) { if(pc.readable()) { device.putc(pc.getc()); } if(device.readable()) { pc.putc(device.getc()); } } }
Attach to RX Interrupt
#include "mbed.h" DigitalOut led1(LED1); DigitalOut led2(LED2); Serial pc(USBTX, USBRX); void callback() { // Note: you need to actually read from the serial to clear the RX interrupt printf("%c\n", pc.getc()); led2 = !led2; } int main() { pc.attach(&callback); while (1) { led1 = !led1; wait(0.5); } }
- See full attach API | https://developer.mbed.org/handbook/Serial | CC-MAIN-2016-50 | refinedweb | 429 | 60.95 |
Opened 7 years ago
Closed 6 years ago
Last modified 5 years ago
#15237 closed Bug (fixed)
Django generated Atom/RSS feeds don't specify charset=utf8 in their Content-Type
Description
Atom feeds containing UTF8 characters should be served with a Content-Type of "application/atom+xml; charset=utf8". At the moment Django's default behaviour is to serve them without the charset bit, and it's not particularly easy to over-ride this behaviour:
The workaround I'm using at the moment is to wrap the feed in a view function which over-rides the content-type on the generated response object, but it's a bit of a hack:
def feed(request): response = MyFeed()(request) response['Content-Type'] = 'application/atom+xml; charset=utf-8' return response
Attachments (3)
Change History (22)
comment:1 Changed 7 years ago by
comment:2 Changed 7 years ago by
Since the syndication framework actually writes everything in utf-8 in the view (see) this should be a case of just adding "; charset=utf8" to the line simon is referring to?
comment:3 Changed 7 years ago by
comment:4 Changed 7 years ago by
Assertion "Atom feeds containing UTF8 characters should be served with a Content-Type of "application/atom+xml; charset=utf8"." verified here: (mime-type syntax) and here: (recommendation to always set the charset).
Although it does appear that if the charset is set in the XML declaration, i.e. <?xml version="1.0" encoding="utf-8"?> , then the charset in the Content-Type is not required, since everything within that XML document is supposed to be treated as UTF8. However, it is still recommended so will proceed.
Looks like the code in /django/contrib/syndication/views.py does not set the mime-type, it only uses it. It is the util code in /django/utils/feedgenerator.py that sets it, as mentioned above.
Can't find anything in the docs that requires changing due to this small change.
Added regression test to verify the MIME type is still set with encoding in the future.
Changed 7 years ago by
SVN diff
comment:5 Changed 7 years ago by
comment:6 Changed 7 years ago by
comment:7 Changed 6 years ago by
Another workaround for this issue, is extending feed class:
from django.contrib.syndication.views import Feed from django.utils import feedgenerator class FeedUTF8(feedgenerator.DefaultFeed): def __init__(self, *args, **kwargs): super(FeedUTF8, self).__init__(*args, **kwargs) self.mime_type = '%s; charset=utf-8' % self.mime_type
And then specify the feed_type:
class LatestEntriesFeed(Feed): ... feed_type = FeedUTF8
...
$ curl -I HTTP/1.0 200 OK Date: Thu, 31 Mar 2011 16:40:26 GMT Server: WSGIServer/0.1 Python/2.6.1 Content-Type: application/rss+xml; charset=utf-8
comment:8 Changed 6 years ago by
The charset should be “utf-8” rather than “utf8”, since the latter isn't what's registered with IANA. See:.
comment:9 Changed 6 years ago by
comment:10 Changed 6 years ago by
Bug confirmed: (link given in a previous comment) says
'utf-8' and not
'utf8'.
While investigating this problem, I noticed that the codebase consistently uses
<unicode>.encode('utf-8'), except one instance in
tests/regressiontests/signing/tests.py, where the dash is missing. The
codecs module defines
utf8 as an alias of
utf-8, so the code works, but there's no reason to keep this exception. I included that fix in the patch too — feel free to commit it separately or not commit it at all.
PS : you could have opened a new ticket instead of reopening this one, because strictly speaking, it's a different issue.
Changed 6 years ago by
comment:11 Changed 6 years ago by
Acting like another set of eyes. Seems pretty straightforward — RFC.
comment:12 Changed 6 years ago by
comment:13 Changed 6 years ago by
Milestone 1.3 deleted
comment:14 Changed 6 years ago by
This fix only seems to have been applied to Atom feeds, and not RSS feeds.
Is there a reason for this? If not, could it please also be applied to RSS feeds?
One use case is: debugging feeds with Google Chrome, which displays them in text/plain, and therefore doesn't parse the document level encoding attribute (<?xml version="1.0" encoding="utf-8"?>). The result is it uses an incorrect encoding (e.g. country’s, instead of country's).
comment:15 Changed 6 years ago by
Given the previous argument that Feed always writes the content in UTF-*, it sound reasonable to me. And as the original ticket mentions both Atom and RSS, I think it's ok to reopen this ticket.
Changed 6 years ago by
Added charset to RSS feeds
comment:16 Changed 6 years ago by
comment:17 Changed 6 years ago by
comment:18 follow-up: 19 Changed 5 years ago by
Any chance for it to be backported to 1.3?
This seems like a reasonable request. I'm not an expert on the feeds framework, but it doesn't look like it ever produces things which are NOT UTF-8, so hopefully the fix is trivial. | https://code.djangoproject.com/ticket/15237 | CC-MAIN-2017-34 | refinedweb | 859 | 62.88 |
wcrtomb man page
Prolog)
Synopsis
#include <wchar.h> size_t wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict ps);
Description
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard. POSIX.1-2008.
Return Value.
Errors
The wcrtomb() function shall fail if:
- EILSEQ
An invalid wide-character code is detected.
The wcrtomb() function may fail if:
- EINVAL
ps points to an object that contains an invalid conversion state.
The following sections are informative.
Examples
None.
Application Usage
None.
Rationale
None.
Future Directions
None.
See Also
mbsinit(), wcsrtombs()printf(3p), fscanf(3p), fwscanf(3p), mbsinit(3p), wchar.h(0p), wcsrtombs(3p). | https://www.mankier.com/3p/wcrtomb | CC-MAIN-2017-47 | refinedweb | 129 | 52.46 |
Using SqlFileStream with C# to Access SQL Server FILESTREAM Data
FILESTREAM is a powerful feature in SQL Server that stores varbinary(max) column data (BLOBs) in the file system (where BLOBs belongs) rather than in the database’s structured file groups (where BLOBs kill performance). This feature was first introduced in SQL Server 2008, and is now being expanded with the new FileTable feature coming in SQL Server 2012 (code-named “Denali”). This post contains abbreviated updated FILESTREAM coverage that I’ll be adding to Tallan’s new book Programming SQL Server 2012 (to be published, hopefully, shortly after the first quarter of 2012).
If you’re not already familiar with FILESTREAM, you can get the necessary background by reading these two articles: Introducing FILESTREAM and Enabling and Using FILESTREAM. In this post, I’ll show you how to use the SqlFileStream class to achieve high-performance streaming of SQL Server FILESTREAM data in your .NET applications (the code is shown in C#, but can be written in VB .NET as well).
What Is SqlFileStream?
SqlFileStream is a class in the .NET Framework (.NET 3.5 SP1 and higher) that wraps the OpenSqlFilestream function exposed by the SQL Server Native Client API. This lets you stream BLOBs directly between SQL Server and your .NET application (written in C# or VB .NET). SqlFileStream is always used within a transaction. You create a SqlFileStream object when you are ready to store and retrieve BLOBs from varbinary(max) FILESTREAM columns. Just at that point in time, SQL Server will “step aside” and let you stream directly against the server’s file system—a native environment optimized for streaming. This provides you with a streaming “tunnel” between your application and SQL Server’s internally-managed file system. Using SqlFileStream will give your application lightning-fast BLOB performance. Let’s dive in!
Creating the Database
Before getting started, be sure that FILESTREAM is enabled for remote file system access at both the Windows Service and SQL Server instance levels (as explained in Enabling and Using FILESTREAM). Then create a FILESTREAM-enabled database as follows (be sure to create the directory, C:\DB in this example, before creating the database):')
Next, use the database and create a table for BLOB storage as follows:
USE PhotoLibrary GO CREATE TABLE PhotoAlbum( PhotoId int PRIMARY KEY, RowId uniqueidentifier ROWGUIDCOL NOT NULL UNIQUE DEFAULT NEWID(), Description varchar(max), Photo varbinary(max) FILESTREAM DEFAULT(0x))
In this table, the Photo column is declared as varbinary(max) FILESTREAM, and will hold pictures that will be stored in the file system behind the scenes. (Refer to Enabling and Using FILESTREAM for a complete explanation of the varbinary(max) FILESTREAM and ROWGUIDCOL columns.) Notice the default value we’ve established for the BLOB column. The value 0x represents a zero-length binary stream, which is different than NULL. Think of it as the difference between a zero-length string and a null string in .NET; the two are not the same. Similarly, you won’t be able to use SqlFileStream against NULL instances of varbinary(max) FILESTREAM columns, and you’ll soon see why.
Writing SqlFileStream Code
Start Visual Studio, create a new Class Library project, and add a PhotoData class as follows:
using System; using System.Data; using System.Data.SqlClient; using System.Data.SqlTypes; using System.Drawing; using System.IO; using System.Transactions; namespace PhotoLibraryApp { public class PhotoData { private const string ConnStr = "Data Source=.;Integrated Security=True;Initial Catalog=PhotoLibrary;"; public static void InsertPhoto (int photoId, string desc, string filename) { const string InsertTSql = @" INSERT INTO PhotoAlbum(PhotoId, Description) VALUES(@PhotoId, @Description); SELECT Photo.PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT() FROM PhotoAlbum WHERE PhotoId = @PhotoId"; string serverPath; byte[] serverTxn; using (TransactionScope ts = new TransactionScope()) { using (SqlConnection conn = new SqlConnection(ConnStr)) { conn.Open(); using (SqlCommand cmd = new SqlCommand(InsertTSql, conn)) { cmd.Parameters.Add("@PhotoId", SqlDbType.Int).Value = photoId; cmd.Parameters.Add("@Description", SqlDbType.VarChar).Value = desc; using (SqlDataReader rdr = cmd.ExecuteReader()) { rdr.Read(); serverPath = rdr.GetSqlString(0).Value; serverTxn = rdr.GetSqlBinary(1).Value; rdr.Close(); } } SavePhotoFile(filename, serverPath, serverTxn); } ts.Complete(); } } private static void SavePhotoFile (string clientPath, string serverPath, byte[] serverTxn) { const int BlockSize = 1024 * 512; using (FileStream source = new FileStream(clientPath, FileMode.Open, FileAccess.Read)) { using (SqlFileStream dest = new SqlFileStream(serverPath, serverTxn, FileAccess.Write)) { byte[] buffer = new byte[BlockSize]; int bytesRead; while ((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0) { dest.Write(buffer, 0, bytesRead); dest.Flush(); } dest.Close(); } source.Close(); } } public static Image SelectPhoto(int photoId, out string desc) { const string SelectTSql = @" SELECT Description, Photo.PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT() FROM PhotoAlbum WHERE PhotoId = @PhotoId"; Image photo; string serverPath; byte[] serverTxn; using (TransactionScope ts = new TransactionScope()) { using (SqlConnection conn = new SqlConnection(ConnStr)) { conn.Open(); using (SqlCommand cmd = new SqlCommand(SelectTSql, conn)) { cmd.Parameters.Add("@PhotoId", SqlDbType.Int).Value = photoId; using (SqlDataReader rdr = cmd.ExecuteReader()) { rdr.Read(); desc = rdr.GetSqlString(0).Value; serverPath = rdr.GetSqlString(1).Value; serverTxn = rdr.GetSqlBinary(2).Value; rdr.Close(); } } photo = LoadPhotoImage(serverPath, serverTxn); } ts.Complete(); } return photo; } private static Image LoadPhotoImage(string filePath, byte[] txnToken) { Image photo; using (SqlFileStream sfs = new SqlFileStream(filePath, txnToken, FileAccess.Read)) { photo = Image.FromStream(sfs); sfs.Close(); } return photo; } } }
Let’s explain the code in detail. We’ll start at the top with some required namespace inclusions. The two using statements to take notice of are System.Data.SqlTypes and System.Transactions. The System.Data.SqlTypes namespace defines the SqlFileStream class that we’ll be using to stream BLOBs. No special assembly reference is required to use this class, because it is provided by the System.Data.dll assembly that our project is already referencing (Visual Studio set this reference automatically when it created our project). The System.Transactions namespace defines the TransactionScope class that lets us code implicit transactions against the database. This class is provided by the System.Transactions.dll assembly, which is not referenced automatically. You’ll need to add a reference to it now, or the code will not compile. Right-click the project in Solution Explorer and choose Add Reference. In the Add Reference dialog, click the .NET tab, and scroll to find the System.Transactions component. Then double-click it to add the reference.
At the top of the class, we define a connection string as a hard-coded constant named ConnStr. This is just for demonstration purposes; a real-world application would store the connection string elsewhere (such as in a configuration file, possibly encrypted), but we’re keeping our example simple.
Streaming Into SQL Server
The first method defined in the class is InsertPhoto, which accepts a new photo integer ID, string description, and full path to an image file to be saved to the database. Notice that the InsertTSql string constant defined at the top of the method specifies an INSERT statement that includes the PhotoId and Description columns, but not the actual Photo BLOB column itself. Instead, the INSERT statement is followed immediately by a SELECT statement that retrieves two pieces of information we’ll use to stream the BLOB into Photo column much more efficiently than using ordinary T-SQL—namely, a logical UNC path name to the file and the transactional context token. These are the two values needed to use SqlFileStream, and you’re about to see how exactly. But all we’ve done so far is define a constant holding two T-SQL statements. The constant is followed by two variables declarations serverPath and serverTxn that will receive the two special values when we later execute those T-SQL statements.
The method then creates and enters a new TransactionScope block. This does not actually begin the database transaction (we’ve not even connected to the database yet), but rather declares that all data access within the block (and in any code called from within the block) must participate in a database transaction. Inside the TransactionScope block, the code creates and opens a new SqlConnection. Being the first data access code inside the TransactionScope block, this also implicitly begins the database transaction. Next, it creates a SqlCommand object associated with the open connection and prepares its command text to contain our T-SQL statements (the INSERT followed by the SELECT).
Invoking the ExecuteReader method executes the T-SQL statements and returns a reader from which we can retrieve the values returned by the SELECT statement. The transaction is still pending at this time. column—and this is exactly how the default 0x value that we defined earlier for the Photo column comes into play (we said we’d come back to it, and here we are).
Although the row has been added by the INSERT statement, it will rollback (disappear) if a problem occurs before the transaction is committed. Because we didn’t provide a BLOB value for the Photo column in the new row, SQL Server honors the default value 0x that we established for it in the CREATE TABLE statement for PhotoAlbum. This represents a zero-length binary stream, which is completely different than NULL. Being a varbinary(max) column decorated with the FILESTREAM attribute, an empty file gets created in the file system that SQL Server associates with the new row. At the same time, SQL Server initiates an NTFS file system transaction over this new empty file and synchronizes it with the database transaction. So just like the new row, the new file will disappear if the database transaction does not commit successfully.
Immediately following the INSERT statement, the SELECT statement returns Photo.PathName and GET_FILESTREAM_TRANSACTION_CONTEXT. What we’re essentially doing with the WHERE clause in this SELECT statement is reading back the same row we have just added (but not yet committed) to the PhotoAlbum table in order to reference the BLOB stored in the new file that was just created (also not yet committed) in the file system.
The value returned by Photo.PathName is a fabricated path to the BLOB for the selected PhotoId. The path is expressed in UNC format, and points to the network share name established for the server instance when we first enabled FILESTREAM (this is MSSQLSERVER in our example, as shown in Figure 9-1). It is not a path the file’s physical location on the server, but rather contains information SQL Server can use to derive the file’s physical location. For example, you’ll notice that it always contains the GUID value in the uniqueidentifier ROWGUIDCOL column of the BLOB’s corresponding row. We retrieve the path value from the reader’s first column and store it in the serverPath string variable.
We just explained how SQL Server initiated an NTFS file system transaction over the FILESTREAM data in the new row’s Photo column when we started our database transaction. The GET_FILESTREAM_TRANSACTION_CONTEXT function returns a handle to that NTFS transaction (if you’re not inside a transaction, this function will return NULL and your code won’t work). We obtain the transaction context, which is returned by the reader’s second column as a SqlBinary value, and store it in the byte array named serverTxn.
Armed with the BLOB path reference in serverPath and the transaction context in serverTxn, we have what we need to create a SqlFileStream object and perform direct file access to stream our image into the Photo column. We close the reader, terminate its using block, then terminate the enclosing using block for the SqlConnection as well. This would normally close the database connection implicitly, but that gets deferred in this case because the code is still nested inside the outer using block for the TransactionScope object. So the connection is still open at this time, and the transaction is still pending. It is precisely at this point that we call the SavePhotoFile method to stream the specified image file into the Photo column of the newly inserted PhotoAlbum row, overwriting the empty file just created by default. When control returns from SavePhotoFile, the TransactionScope object’s Complete method is invoked and its using block is terminated, signaling the transaction management API that everything worked as expected. This implicitly commits the database transaction (which in turn commits the NTFS file system transaction) and closes the database connection.
The SavePhotoFile method reads from the source file and writes to the database FILESTREAM storage in 512 KB chunks at a time using ordinary .NET streaming techniques. The method begins by defining a BlockSize integer constant that is set to a reasonable value of 512 KB. Picture files larger than this will be streamed to the server in 512 KB blocks at a time. The local source image file (in clientPath) is then opened on an ordinary read-only FileStream object.
Then the destination file is opened by passing the two special values (serverPath and serverTxn), along with a FileAccess.Write enumeration requesting write access, into the SqlFileStream constructor. Like the source FileStream object, SqlFileStream inherits from System.IO.Stream, so it can be treated just like any ordinary stream. Thus, you attain write access to the destination BLOB on the database server’s NTFS file system. Remember that this output file is enlisted in an NTFS transaction and nothing you stream to it will be permanently saved until the database transaction is committed by the terminating TransactionScope block, after SavePhotoFile completes. The rest of the SavePhotoFile method implements a simple loop that reads from the source FileStream and writes to the destination SqlFileStream, one 512 KB block at a time until the entire source file is processed, and then it closes both streams.
Streaming Out From SQL Server
The rest of the code contains methods to retrieve existing photos and stream their content from the file system into an Image object for display. You’ll find that this code follows the same pattern as the last, only now we’re performing read access.
The SelectPhoto method accepts a photo ID and returns the string description from the database in an output parameter. The actual BLOB itself is returned as the method’s return value in a System.Drawing.Image object. We populate the Image object with the BLOB by streaming into it from the database server’s NTFS file system using SqlFileStream. Once again, we start things off by entering a TransactionScope block and opening a connection. We then execute a simple SELECT statement that queries the PhotoAlbum table for the record specified by the photo ID and returns the description and full path to the image BLOB, as well as the FILESTREAM transactional context token. And once again we use the path name and transactional context with SqlFileStream to tie into the server’s file system in the LoadPhotoImage method.
Just as when we were inserting new photos (only this time using FileAccess.Read instead of FileAccess.ReadWrite), we create a new SqlFileStream object from the logical path name and transaction context. We then pull the BLOB content directly from the NTFS file system on the server into a new System.Drawing.Image object using the static Image.FromStream method against the SqlFileStream object. The populated image can then be passed back up to a Windows Forms application, where it can be displayed using the Image property of a PictureBox control.
Or, to stream a photo over HTTP from a simple ASP.NET service:
using System; using System.Data; using System.Data.SqlClient; using System.Data.SqlTypes; using System.IO; using System.Transactions; using System.Web.UI; namespace PhotoLibraryHttpService { public partial class PhotoService : Page { private const string ConnStr = "Data Source=.;Integrated Security=True;Initial Catalog=PhotoLibrary"; protected void Page_Load(object sender, EventArgs e) { int photoId = Convert.ToInt32(Request.QueryString["photoId"]); if (photoId == 0) { return; } const string SelectTSql = @" SELECT Photo.PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT() FROM PhotoAlbum WHERE PhotoId = @PhotoId"; using (TransactionScope ts = new TransactionScope()) { using (SqlConnection conn = new SqlConnection(ConnStr)) { conn.Open(); string serverPath; byte[] serverTxn; using (SqlCommand cmd = new SqlCommand(SelectTSql, conn)) { cmd.Parameters.Add("@PhotoId", SqlDbType.Int).Value = photoId; using (SqlDataReader rdr = cmd.ExecuteReader()) { rdr.Read(); serverPath = rdr.GetSqlString(0).Value; serverTxn = rdr.GetSqlBinary(1).Value; rdr.Close(); } } this.StreamPhotoImage(serverPath, serverTxn); } ts.Complete(); } } private void StreamPhotoImage(string serverPath, byte[] serverTxn) { const int BlockSize = 1024 * 512; const string JpegContentType = "image/jpeg"; using (SqlFileStream sfs = new SqlFileStream(serverPath, serverTxn, FileAccess.Read)) { byte[] buffer = new byte[BlockSize]; int bytesRead; Response.BufferOutput = false; Response.ContentType = JpegContentType; while ((bytesRead = sfs.Read(buffer, 0, buffer.Length)) > 0) { Response.OutputStream.Write(buffer, 0, bytesRead); Response.Flush(); } sfs.Close(); } } } }
Conclusion
The OpenSqlFilestream function provides native file streaming capabilities between FILESTREAM storage in the file system managed by SQL Server and any native-code (e.g., C++) application. SqlFileStream provide a managed code wrapper around OpenSqlFilestream that simplifies direct FILESTREAM access from .NET applications (e.g., C# and VB .NET). This post explained how this API works in detail, and showed the complete data access code that uses SqlFileStream for both reading and writing BLOBs to and from SQL Server. That’s everything you need to know to get the most out of FILESTREAM. I hope you enjoyed it!
Thanks for the useful post. But how can we generate strong typed dataset or use EF model for Filestream Varbinary(max) column of sql server
Glad you found it helpful Russell. Fortunately, FILESTREAM is a total abstraction over the varbinary(max) data type, so you can build a typed DataSet against FILESTREAM by designating the BLOB column in your DataTable as a System.Byte[] type (that is, an ordinary byte array). I’ve done it before, and it works perfectly. The same should be true for the Entity Data Model in EF, though I’ve never tested it.
Thanks for a great article. I have implemented most of this in my current project. I am however having a ‘Parameter is Invalid’ error when i try to read the file from NTFS. The photo = Image.FromStream(sfs) line produces the error. Any Thoughts?
Is there a way I can confirm that the files saved in my FileStream folder are valid?
Does any1 have that code in C# windows appication and a downloadable sample
thank you for you help !
[…] Since EF doesn’t support Filestream for now, I’m handling the “File part” through simple Sql requests. I’ve read a good article on filestream usage here: […]
Great article, very useful for me.
Can we make a step further ? How can I use the binary data read from SQL Server?
For example a Word file. How can I display it in native application (MS Word), modify it and save it back to database ?
You use an int to define the pk for the table that holds the BLOB. How do you guarantee a unique pk when the key is sent in as a parameter?
Hey, Let me thanks to you for the article, it is great. I was implementing it as a practice and I have a question. Why the insert creates two files in the files folder, the first one is a oKB and the other one has the size of the file. I mean, for each row inserted it will create two files. I don’t know if maybe that is normal or not. I hope you can help to me ASAP, because I am studying FileStream and I must decide if it would be the best way to implement in my projects.
Thanks in advance.
I’m having difficulties running this code, specifically saving the file with the following error.
“The process cannot access the file specified because it has been opened in another transaction.”
The exception occurs while newing dest = new SqlFileStream(serverPath, serverTxn, FileAccess.Write)
using (var source = new FileStream(clientPath, FileMode.Open, FileAccess.Read)) {
>>>> using (var dest = new SqlFileStream(serverPath, serverTxn, FileAccess.Write)) {
var buffer = new byte[blockSize];
int bytesRead;
while ((bytesRead = source.Read(buffer, 0, buffer.Length)) > 0) {
dest.Write(buffer, 0, bytesRead);
dest.Flush();
}
dest.Close();
}
source.Close();
}
Any advise?
You write in your article the following about SQLFileStream: ” SqlFileStream is always used within a transaction”. Is this also true if the non-transnational access for FileTables is allowed ?
[…] to get the transaction context token. Lenni Lobel has an excellent blog on how to do that here – the same .NET calls would apply in some custom orchestration or pipeline code, with the […]
If you use the BeginRead, CopyTo, or Read methods on the SqlFileStream object, then you re using the SQL server to read the data, not reading it directly. If you re just using SqlFileStream object, you don t need to worry about the NTFS permissions. If you really are accessing the files directly from disk (maybe by using classes from System.IO), then you do, but I also think that is
By the way! The best essay writing service –
And Happy New Year! | https://blog.tallan.com/2011/08/22/using-sqlfilestream-with-c-to-access-sql-server-filestream-data/ | CC-MAIN-2019-35 | refinedweb | 3,443 | 56.66 |
OpenCV allows you to manipulate images and videos. There are many functions in it that perform it. Suppose you want to implement OpenCV edge detection. Then how you can do so. The answer is here. In this entire tutorial, you will know how to detect edges of an image using the cv2 canny method. All tasks will be implemented step by step.
Steps for OpenCV edge detection through cv2 Canny method
Before going through the steps in detail below is the image file I will implement OpenCV edge detection.
Step 1: Import the necessary library
In this tutorial, I am using the OpenCV package only. Make sure you have installed the OpenCV python library. Then import it using the import statement.
import cv2
Step 2: Read the Image File
The next step is to read the image file. Any image in OpenCV can be read using the cv2.imread() method. Execute the code below to read the image.
img = cv2.imread("dove.jpg")
Step 3: Implement the cv2 Canny method.
Now, after reading the image, let’s detect the image using the cv2.Canny() method. Generally, The Canny() method accepts three arguments. The first argument is your input image. The second and third arguments are aperture_size and L2gradient also know as threshold values. Threshold values allow you to classify the pixel intensities in the image.
Let’s use the cv2.Canny() method on the image.
edges = cv2.Canny(img,100,70)
You can see the I am using 100 and 70 as the aperture size and L2 gradient.
Step 4: Show and Compare the Image
After implementing all the above let’s show and compare the image. In OpenCV, you can show the image using the cv2.imshow() method. After that, if you are using cv2 on windows then you have to use cv2.waitKey(0) to display the image indefinitely until you press the keyboard.
cv2.imshow("Canny Image",edges)
Below is the full code for this tutorial and its output.
import cv2 img = cv2.imread("dove.jpg") cv2.imshow("Original Image",img) edges = cv2.Canny(img,100,70) cv2.imshow("Canny Image",edges) cv2.waitKey(0) cv2.destroyAllWindows()
Output
Hurray! You have successfully detected the edge of a dove bird image. In the same way, you can detect edges for any image you want. Just you have to keep varying the threshold values to detect the best edges on the image.
These are steps to implement cv2.Canny() method and detect edges using it. Hope you have liked this tutorial. If you have any queries regarding this post then you can contact us. We are always ready to help you.
Source:
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Creating our First Window
In order to create windows in Java, we are going to need the components located in javax.swing. Well, java.awt also contains window components although they appear to be unstable especially when it comes to different operating environments.
So we start by creating our first window:
import javax.swing.JFrame; import javax.swing.WindowConstants; public class FrameDemo{ public static void main(String args[]){ JFrame myFrame = new JFrame("This is my frame"); myFrame.setSize(300,400); myFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); myFrame.setVisible(true); } }
which would produce an output like this:
Code Explanation
On our first lines of code, we have just imported the library classes which we will use. First is JFrame and the next is WindowConstants. JFrame is used for creating windows. WindowConstants constants needed in creating windows.
On our main method, we create an instance of the JFrame by giving it an object name and a title as well:
JFrame myFrame = new JFrame("This is my frame");
Then we set what will happens when we close the window(such as clicking on the close button):
myFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
we set this in order to make sure that our window exits the moment we close it. Other constants can be used if preferred which are namely:
- DO_NOTHING_ON_CLOSE - nothing happens when you click the close button.
- HIDE_ON_CLOSE - The window dissapears but it is still there. You may show this using the setVisible() method
- DISPOSE_ON_CLOSE - destroys the object created.
try them by replacing the code with these constants to observe the effects. I suggest you use an Integrated Development Environment (IDE) first when you're going to try this. Most IDE's have a stop tool that lets you terminate a process.
And out last line:
myFrame.setVisible(true);
by default, the frame is set by false. Unless you include this code, you won't be seeing it. You may also use this code for hiding frames. We will be using this on our further examples.
Getting Inside
Inheriting our Class
So far, what we were doing on the previous examples was merely just creating a window. If you really want to manipulate a window, you have to build it from inside. One way to do this is to make your class 'be' the window. This method is called, inheritance-which is making your class inherit all properties as well as behaviors. This can be done with the use of the extends keyword.
But before we start, I would like to first introduce to you some container classes:
- JFrame - the basic java application window. It has a title bar and a provision for adding a menu
- JDialog - This usually appears as a prompt for inputting data as well as displaying them.
- JApplet - This is designed to run embedded in a web page. You can draw and add menu components here
- JPanel - used as a container that can be created within a window. Takes also some behaviors of JApplet where you can also draw and add some components except menu types.
Now let us proceed to our program. First we apply these principles to our previous program. The code should look like this:
import javax.swing.JFrame;
public class FrameDemo2 extends JFrame{ /** * Constructor - This method automatically run whenever an object of FrameDemo2 is created. **/ public FrameDemo2(){ super("Behold, our new frame"); } public static void main(String args[]){ FrameDemo2 myFrame = new FrameDemo2(); myFrame.setSize(300,400); myFrame.setLocationRelativeTo(null); myFrame.setDefaultCloseOperation(myFrame.EXIT_ON_CLOSE); myFrame.setVisible(true); } }
The advantage of this code is encapsulation, and designing modular, reusable, and extensible code For example, we could then extend the MyFrame class to further customize it. And this way, we can also set up the JFrame without cramming all the code into one .java File or class (which an author of a book I read called, "The Giant Objects Syndrome").
The super() function is for calling the constructor of the base class(the class inherited from) which specifies the title. This is just for giving your frame a default title. I almost forgot, you can set the title of the frame by using the setTitle() property:
myFrame.setTitle("This is the customized title");
Reference:
Beginning Java 2 by Ivor Horton
Thinking in Java by Bruce Eckel
You can also find this topic in Squidoo.com(Basic GUI in JAVA) | https://www.dreamincode.net/forums/topic/206344-basic-gui-in-java-using-jframes/ | CC-MAIN-2020-10 | refinedweb | 718 | 56.35 |
I'm building a WSGI web app and I have a MySQL database. I'm using MySQLdb, which provides cursors for executing statements and getting results. What is the standard practice for getting and closing cursors? In particular, how long should my cursors last? Should I get a new cursor for each transaction?
I believe you need to close the cursor before committing the connection. Is there any significant advantage to finding sets of transactions that don't require intermediate commits so that you don't have to get new cursors for each transaction? Is there a lot of overhead for getting new cursors, or is it just not a big deal?
Instead of asking what is standard practice, since that's often unclear and subjective, you might try looking to the module itself for guidance. In general, using the
with keyword as another user suggested is a great idea, but in this specific circumstance it may not give you quite the functionality you expect.
As of version 1.2.5 of the module,
MySQLdb.Connection implements the context manager protocol with the following code (github):
def __enter__(self): if self.get_autocommit(): self.query("BEGIN") return self.cursor() def __exit__(self, exc, value, tb): if exc: self.rollback() else: self.commit()
There are several existing Q&A about
with already, or you can read Understanding Python's "with" statement, but essentially what happens is that
__enter__ executes at the start of the
with block, and
__exit__ executes upon leaving the
with block. You can use the optional syntax
with EXPR as VAR to bind the object returned by
__enter__ to a name if you intend to reference that object later. So, given the above implementation, here's a simple way to query your database:
connection = MySQLdb.connect(...) with connection as cursor: # connection.__enter__ executes at this line cursor.execute('select 1;') result = cursor.fetchall() # connection.__exit__ executes after this line print result # prints "((1L,),)"
The question now is, what are the states of the connection and the cursor after exiting the
with block? The
__exit__ method shown above calls only
self.rollback() or
self.commit(), and neither of those methods go on to call the
close() method. The cursor itself has no
__exit__ method defined – and wouldn't matter if it did, because
with is only managing the connection. Therefore, both the connection and the cursor remain open after exiting the
with block. This is easily confirmed by adding the following code to the above example:
try: cursor.execute('select 1;') print 'cursor is open;', except MySQLdb.ProgrammingError: print 'cursor is closed;', if connection.open: print 'connection is open' else: print 'connection is closed'
You should see the output "cursor is open; connection is open" printed to stdout.
I believe you need to close the cursor before committing the connection.
Why? The MySQL C API, which is the basis for
MySQLdb, does not implement any cursor object, as implied in the module documentation: "MySQL does not support cursors; however, cursors are easily emulated." Indeed, the
MySQLdb.cursors.BaseCursor class inherits directly from
object and imposes no such restriction on cursors with regard to commit/rollback. An Oracle developer had this to say:
cnx.commit() before cur.close() sounds most logical to me. Maybe you can go by the rule: "Close the cursor if you do not need it anymore." Thus commit() before closing the cursor. In the end, for Connector/Python, it does not make much difference, but or other databases it might.
I expect that's as close as you're going to get to "standard practice" on this subject.
Is there any significant advantage to finding sets of transactions that don't require intermediate commits so that you don't have to get new cursors for each transaction?
I very much doubt it, and in trying to do so, you may introduce additional human error. Better to decide on a convention and stick with it.
Is there a lot of overhead for getting new cursors, or is it just not a big deal?
The overhead is negligible, and doesn't touch the database server at all; it's entirely within the implementation of MySQLdb. You can look at
BaseCursor.__init__ on github if you're really curious to know what's happening when you create a new cursor.
Going back to earlier when we were discussing
with, perhaps now you can understand why the
MySQLdb.Connection class
__enter__ and
__exit__ methods give you a brand new cursor object in every
with block and don't bother keeping track of it or closing it at the end of the block. It's fairly lightweight and exists purely for your convenience.
If it's really that important to you to micromanage the cursor object, you can use contextlib.closing to make up for the fact that the cursor object has no defined
__exit__ method. For that matter, you can also use it to force the connection object to close itself upon exiting a
with block. This should output "my_curs is closed; my_conn is closed":
from contextlib import closing import MySQLdb with closing(MySQLdb.connect(...)) as my_conn: with closing(my_conn.cursor()) as my_curs: my_curs.execute('select 1;') result = my_curs.fetchall() try: my_curs.execute('select 1;') print 'my_curs is open;', except MySQLdb.ProgrammingError: print 'my_curs is closed;', if my_conn.open: print 'my_conn is open' else: print 'my_conn is closed'
Note that
with closing(arg_obj) will not call the argument object's
__enter__ and
__exit__ methods; it will only call the argument object's
close method at the end of the
with block. (To see this in action, simply define a class
Foo with
__enter__,
__exit__, and
close methods containing simple
with Foo(): pass to what happens when you do
with closing(Foo()): pass.) This has two significant implications:
First, if autocommit mode is enabled, MySQLdb will
BEGIN an explicit transaction on the server when you use
with connection and commit or rollback the transaction at the end of the block. These are default behaviors of MySQLdb, intended to protect you from MySQL's default behavior of immediately committing any and all DML statements. MySQLdb assumes that when you use a context manager, you want a transaction, and uses the explicit
BEGIN to bypass the autocommit setting on the server. If you're used to using
with connection, you might think autocommit is disabled when actually it was only being bypassed. You might get an unpleasant surprise if you add
closing to your code and lose transactional integrity; you won't be able to rollback changes, you may start seeing concurrency bugs and it may not be immediately obvious why.
Second,
with closing(MySQLdb.connect(user, pass)) as VAR binds the connection object to
VAR, in contrast to
with MySQLdb.connect(user, pass) as VAR, which binds a new cursor object to
VAR. In the latter case you would have no direct access to the connection object! Instead, you would have to use the cursor's
connection attribute, which provides proxy access to the original connection. When the cursor is closed, its
connection attribute is set to
None. This results in an abandoned connection that will stick around until one of the following happens:
You can test this by monitoring open connections (in Workbench or by using
SHOW PROCESSLIST) while executing the following lines one by one:
with MySQLdb.connect(...) as my_curs: pass my_curs.close() my_curs.connection # None my_curs.connection.close() # throws AttributeError, but connection still open del my_curs # connection will close here | https://codedump.io/share/nLQbLP8UQmYv/1/when-to-close-cursors-using-mysqldb | CC-MAIN-2017-04 | refinedweb | 1,250 | 56.66 |
Strange CLI .exit issue
(1) By anonymous on 2021-03-19 17:39:08 [link] [source]
(This is under Win7. It may or may not affect other platforms.)
When reading a script from a pipe and the script contains
.exit followed by many [1] lines, an error is issued like:
c:\temp>sample.sql The process tried to write to a nonexistent pipe.
The setup (from administrator console) is:
ftype sqlite3=cmd /c "type %1 | c:\bins\sqlite3.exe -batch %*" assoc .sql=sqlite3
I'm almost certain this worked forever but I can't tell when it stopped working as I only keep the latest (3.35.2) plus the previous release, and it's present in both.
Has something changed lately with respect to stdin processing?
I'm not sure it's SQLite3's fault but given that Win7 is no longer updated I doubt there is a change Win7.
[1] How many is 'many'? I see the problem with about 120 lines following
.exit while fewer lines make it go away (possibly this is related to the file buffer used by ether Windows or SQLite).
(2) By anonymous on 2021-03-22 21:06:17 in reply to 1 [link] [source]
(OP here) I seem to have solved it this way:
--- src/shell.c.in +++ src/shell.c.in @@ -7845,10 +7845,11 @@ rc = 1; } }else if( c=='e' && strncmp(azArg[0], "exit", n)==0 ){ + while (fgetc(p->in) != EOF); if( nArg>1 && (rc = (int)integerValue(azArg[1]))!=0 ) exit(rc); rc = 2; }else
The line numbers correspond to my modified version so they may not match official source. But it's in that vicinity.
As I have no knowledge of SQLite3 internals, can someone verify if this seems correct solution?
(3) By Larry Brasfield (larrybr) on 2021-03-22 23:06:41 in reply to 2 [link] [source]
Earlier, you wrote:
If you entered that command, literally, the %1 and %* will expand to nothing as seen by ftype. I'm going to pretend below that you escaped the % characters.
When the system shell expands this for the extension you have associated with "sqlite" files, for the command line "sample.sql" the result will be:
cmd /c type sample.sql | c:\bins\sqlite3.exe -batch sample.sql
, which you must admit is strange. As your sqlite3 invocation is written, it will try to open sample.sql as a database, and as the whole pipeline is written/read, the type command will be trying to copy its content to stdout which is piped to sqlite3's stdin. I'm not sure what should happen in this case, but I am far from declaring that what you have reported as happening should not happen and represents a fixable bug in the SQLite3 shell.
Given that I do not see a bug, I see the correct solution as "do nothing". And because your solution is not "do nothing", I suspect it is incorrect.
If you could show a shell usage scenario for which useful behavior should be expected from the ordinary, understandable rules of cmd.exe [a] but cannot happen due to sqlite3.exe's behavior, we may have a bona fide bug. But I'm not there yet.
a. That's not entirely a joke. There are some commonly understood rules, and the interaction of a file being both opened by "type" and opened by another process for exclusive access is not among that rule set.
(4) By Keith Medcalf (kmedcalf) on 2021-03-22 23:32:18 in reply to 3 [link] [source]
Try typing the following command:
help ftype
at a command prompt near you. You will note that %0 and %1 are the object-name (the command filename) and %* are all the parameters to the command-file.
(5.1) By Keith Medcalf (kmedcalf) on 2021-03-22 23:55:53 edited from 5.0 in reply to 2 [link] [source]
Do you get the same result if you do not use the pipe but merely attach the file to stdin?
ftype sqlite3=cmd.exe /c ""C:\Apps\NTUtils\sqlite.exe" -batch < "%1" %*"
Change the specifier for the executable to use your executable. Also, parsing the redirectors is a shell function, so you must have the shell parse the command line -- you cannot start the executable directly.
(6) By Keith Medcalf (kmedcalf) on 2021-03-22 23:41:31 in reply to 5.0 [link] [source]
Note that if I use your pipe then I get an error too on Windows 10 (and probably every other version of DOS / OS/2 / OS/2 New Technology (aka NT) to have ever existed.
(7.1) By Keith Medcalf (kmedcalf) on 2021-03-23 00:28:02 edited from 7.0 in reply to 4 [link] [source]
Note that for austerity %L is also the object-name (command filename) because some people cannot tell the difference between %1 and %l (they use silly fonts or need a new spectacle prescription).
(8) By Keith Medcalf (kmedcalf) on 2021-03-22 23:55:03 in reply to 6 [link] [source]
Modify that because DOS (and other single tasking) Operating Systems process the pipe operator (|) as running the command before the pipe to completion and redirecting stdout to a temp file, then run the command after the pipe with stdin attached to the temp file.
Only Operating Systems which process pipes (|) by running the two processes in parallel with stdout of the first attached to stdin of the latter will experience the first process thowing an error if the consumer closes the pipe before the producer is done producing. Some common examples that this applies to are some versions of Concurrrent DOS, OS/2, OS/2 New Technology (aka Windows NT and its derivatives up to and including Windows 10), Linux, and the Unix and unix-like systems, including Mac OS X (but not MacOS), and QNX.
(9) By anonymous on 2021-03-23 00:20:31 in reply to 2 [link] [source]
The problem I reported is both accurate and real. The setup using FTYPE is also 100% correct as is. It expands to a new CMD running the command:
type sample.sql | c:\bins\sqlite3 --batch
I won't dignify bad-tempered/rude, and above all WRONG answers with a reply. (This is, unfortunately, a recurrent theme in this forum by various members.)
The proposed change I posted I have already tried and it appears to have solved the problem in my limited testing. I'm just not sure if it's correct in the sense it does not have ill side-effects as I don't know SQLite3 source.
What it does (or rather, should do, if there are no side bugs), is simply consume all chars until end-of-file upon
.exit command.
I did not ask for an opinion on the correctness of my setup, only of the 'fix'.
If one can't see the problem in the original - that TYPE feeds SQLite3 with data after SQLite3 has stopped running - I can't help. It's not SQLite3's problem per se (so technically not a bug) as Windows could stop feeding a dead process data, but if it can be solved from within SQLite3 very simply, why not?
(10) By Larry Brasfield (larrybr) on 2021-03-23 00:40:05 in reply to 7.1 [link] [source]
You may consider me now somewhat more educated than before. Thanks.
There are still people around who used typewriters that have no '1' key left of the '2' key because the 'l' (pronounced "el") key was routinely used to produce the smallest non-zero numeral, and nobody saw the folly of it!
(11) By Rowan Worth (sqweek) on 2021-03-23 03:33:23 in reply to 10 [link] [source]
ITYM and nobody saw the fo11y of it!
(12) By Larry Brasfield (larrybr) on 2021-03-23 08:11:01 in reply to 9 [link] [source]
The problem I reported is both accurate and real. The setup using FTYPE is also 100% correct as is. It expands to a new CMD running the command:
type sample.sql | c:binssqlite3 --batch
I can see, from running a cmd.exe session (which I take to be your "administrator console"), that it runs ftype commands differently from most others, in that it does not expand %-preceded words. That's not surprising because cmd.exe is chock-full of quirky exceptions like that. I suppose I should have known, and so I will cop to an error on my absence of quoting comment. I do not accept that that comment was rude, however.
I also accept Keith's corrective point and explanation that argument expansion by the Windows GUI shell is done in a certain way, different from cmd.exe's interpretation of the same argument expressions. I will cop to the additional error of supposing that those expansions occur the same way. However, I do not accept that my erroneous statement of supposed expansion was rude.
... it appears to have solved the problem ... it ... consume all chars until end-of-file upon .exit command.
I did not ask for an opinion on the correctness of my setup, only of the 'fix'.
I stand by my conclusion that there is nothing to fix. The broken pipe message is not something to be avoided by changing potential consumers to read everything in the stream. The message normally indicates either that there has been a mismatch between what a stream producer produces and what a stream consumer expects, or that the consumer terminated prematurely without consuming what was expected to be consumed. The detection of a "broken pipe" and what to say about it are the responsibility of the invoking shell that setup the "pipe" connections. It would be overly presumptuous, IMO, for a consumer to preclude such reports by consuming all input regardless of its content. While some users may dislike seeing broken pipe reports, others value them as indicators that something unexpected is happening.
In this case, the SQLite shell consumes its standard input up to and including the .quit or .exit meta-command and its terminating newline. It should do no more and no less for valid input. It would be a disfavor to those who (arrange to) pipe input into the SQLite shell to deprive them of the useful diagnostic that there is extra garbage in the pipeline. To those who disagree, I would ask what should be the result of doing this on a *Nix system:
cat myValidSQLiteShellInput /dev/zero | sqlite3 -batch
?
(13) By anonymous on 2021-03-23 08:59:44 in reply to 12 [link] [source]
It would be overly presumptuous, IMO, for a consumer to preclude such reports by consuming all input regardless of its content.
Except that upon
.exit there is a guarantee no more input is needed.
While some users may dislike seeing broken pipe reports, others value them as indicators that something unexpected is happening.
The problem also appears from within editors, and it's more serious than just an annoying (possibly useful to some) message. The difference in that case is the editor (PNotepad to be specific for my case) just hangs. And this is very annoying.
In any case, I don't propose SQLite3 to 'fix' this in the official source.
I just care to fix my own copy that gives me trouble.
And to that end, I still don't have an opinion on whether the code I showed seems to be correct in that it does not cause other problems.
(14) By anonymous on 2021-03-23 09:10:23 in reply to 13 [link] [source]
If a program writes to a pipe, it has to watch out for a broken pipe signal (i.e. if the next program in the pipe terminates) and stop writing in this case.
It is the "type" program and the editors that show buggy behaviour and need to be fixed.
(15) By Larry Brasfield (larrybr) on 2021-03-23 09:16:17 in reply to 13 [link] [source]
I see only two improvable aspects to your "fix".
One is that for never-ending stream producers, which keep their output open and keep writing to it sometimes instead of closing it, your fixed shell will never terminate. Whether that is correct depends on expectation, which is a bit vague now.
The other is that the same treatment would logically apply to the .quit meta-command. Unless, of course, that is to differ for some reason.
I cannot see any other problems your "fix" creates, beyond the issue with defeating broken pipe detection already mentioned.
(16) By Keith Medcalf (kmedcalf) on 2021-03-23 09:21:40 in reply to 13 [link] [source]
In the particular case you have described it will solve the issue and not create other problems for that particular case.
How it will behave when some other thing opens uses popen (for example) to sqlite3.exe depends on that other thing and its expectations.
(17) By TripeHound on 2021-03-23 11:07:49 in reply to 13 [link] [source]
A possibly pertinent question is why you sometimes have 120 lines or more in your script file after the
.exit command?.
(18) By anonymous on 2021-03-23 11:09:50 in reply to 12 [link] [source]
While some users may dislike seeing broken pipe reports, others value them as indicators that something unexpected is happening.
And that is exactly why this should be fixed. If people get used to broken pipe errors caused by something like this, they will eventually ignore the real errors.
(19) By anonymous on 2021-03-23 11:10:01 in reply to 16 [link] [source]
Thank you all
(20) By anonymous on 2021-03-23 11:12:29 in reply to 17 [link] [source]
... why you sometimes have 120 lines or more in your script file after the .exit command?
Because I use
.exit for debugging.
During debugging I may want to exit after the part of interest (e.g. some
SELECT) without running additional code that possibly also produces unwanted tons of output.
(21.1) By Richard Hipp (drh) on 2021-03-23 12:30:29 edited from 21.0 in reply to 1 [link] [source]
This is as it should be.
Can you give an example of any other utility or program that continues reading its input after instructed to exit? I can't find one. The most obvious case of a program that does this is the the "head" utility. It also simply stops reading its input and exits once it acquires the requested number of lines. Upstream programs that are concerned about broken pipes will complain. I cannot come up with any other program that behaves differently. Why should SQLite be any different?
What if I have a 1MB script in which ".exit" occurs on the 5th line. You would have SQLite read the entire 1MB just in case the script was piped in? I don't think so.
The ".exit" command means "stop reading input and exit". You are asking to redefine ".exit" to mean "read and ignore all subsequent input and then quit". That is a very different thing, and something I do not want to support.
If you really need to avoid broken pipe errors, I suggest you write a new utility program that does that for you. Here is a TCL script called "shunt.tcl" that transfers content from input to output, but if the output pipe closes, it continues reading the input to avoid complaints from the upstream producers:
while {![eof stdin]} { if {[catch {puts [gets stdin]; flush stdout}]} { while {![eof stdin]} {gets stdin} } }
With this program you could do:
ftype sqlite3=cmd /c "type %1 | tclsh shunt.tcl | c:\bins\sqlite3.exe -batch %*"
The shunt.tcl script will nicely catch and suppress the broken pipe error for you. That would be the proper solution to this problem.
The sqlite3.exe program is currently working as it ought with respect to the .exit command and reading standard input.
(22) By anonymous on 2021-03-23 13:16:13 in reply to 21.1 [link] [source]
The sqlite3.exe program is currently working as it ought with respect to the .exit command and reading standard input.
Let me make clear once again, I never asked for the change to be part of the official SQLite3.
Initially, I was curious how come I never encountered it before (same workflow for years) so maybe something had changed in the CLI, and then if my found solution for my own deviant copy seems correct given I have no clue about SQLite3 source internals.
So, I simply asked if someone could see a problem with the way I did it. That's all.
Can you give an example of any other utility or program that continues reading its input after instructed to exit? I can't find one.
I already mentioned that my editor (PNotepad using just
sqlite3.exe --batch) hangs. Again, this could be a problem with that editor.
What if I have a 1MB script in which ".exit" occurs on the 5th line. You would have SQLite read the entire 1MB just in case the script was piped in? I don't think so.
Sure. Only if one could know when the stdin is redirected, then it could consume only for that case. Again, that's only for own use, so pay no more attention to it.
On the other hand, you could think of all content that follows as wrapped inside a false #ifdef ... #endif block. I believe a compiler would read all the way to find the matching #endif. So, it's a matter of perspective.
(23) By anonymous on 2021-03-24 13:13:23 in reply to 2 [link] [source]
(OP here) Sadly, the previous 'fix' caused a crash when
.exit is given interactively instead of being read from a file (either redirected or by
.read command).
An improved possibility is probably this:
--- src/shell.c.in +++ src/shell.c.in @@ -7845,11 +7845,12 @@ rc = 1; } }else if( c=='e' && strncmp(azArg[0], "exit", n)==0 ){ + if( !stdin_is_interactive && p->in==stdin ) + while (fgetc(p->in) != EOF); if( nArg>1 && (rc = (int)integerValue(azArg[1]))!=0 ) exit(rc); rc = 2; }else
... always pending review from eager SQLite3 insiders ...
(24) By Larry Brasfield (larrybr) on 2021-03-24 14:28:04 in reply to 23 [link] [source]
It was not a "crash". It was a "read stdin to end-of-stream." That condition can be effected by typing control-Z at the beginning of a line on Windows.
No comment on checking for stdin_is_interactive, except this: I dislike programs that act differently depending on whether input or output is redirected. It complicates the mental model, and compromises modularity.
(25) By anonymous on 2021-03-24 15:01:14 in reply to 24 [source]
Actually, it appeared like a "crash"; a Windows popup saying the program has stopped working, and you can no longer interact with the program.
As for using
stdin_is_interactive I found it inside sqlite3 source so I suppose if it's already used for something else why not here too.
(26) By Larry Brasfield (larrybr) on 2021-03-24 17:44:18 in reply to 25 [link] [source]
The code you showed earlier, which read whatever stream was known as stdin until seeing EOF from it, had the behavior I stated and should not have crashed. You claimed that it solved your problem, implying that it read stdin up to getting EOF rather than "crashing". I'm just pointing out that such input sucking is going to go on for a long time when stdin is the console input, presumably coming from a typing person, until they indicate end-of-stream as I indicated.
Of course, I cannot speak to "crashing" for code you have not shown.
My preference for programs acting the same when fed by redirected input as when typed at comes from seeing the complications that ensue and increased trouble-shooting inconvenience. You should suit yourself on that, of course. Once you have many parts of a system acting differently according to how they are connected to each other, and find it difficult to debug and reason about, you may appreciate the point. | https://sqlite.org/forum/info/21cb16739f321784?t=c | CC-MAIN-2022-40 | refinedweb | 3,389 | 72.16 |
Definition at line 2212 of file OptionParser.h.
#include </home/sftnight/build/workspace/root-makedoc-master/rootspi/rdoc/src/master/core/dictgen/res/OptionParser.h>
Constructs a LineWrapper that wraps its output to fit into screen columns
x1 (incl.) to
x2 (excl.).
x1 gives the indentation LineWrapper uses if it needs to indent.
Definition at line 2421 of file OptionParser.h.
Definition at line 2246 of file OptionParser.h.
Definition at line 2251 of file OptionParser.h.
Call BEFORE reading ...buf[tail].
Definition at line 2264 of file OptionParser.h.
Definition at line 2256 of file OptionParser.h.
Writes out all remaining data from the LineWrapper using
write.
Unlike process() this method indents all lines including the first and will output a \n at the end (but only if something has been written).
Definition at line 2308 of file OptionParser.h.
Writes (data,len) into the ring buffer.
If the buffer is full, a single line is flushed out of the buffer into
write.
Definition at line 2273 of file OptionParser.h.
Process, wrap and output the next piece of data.
process() will output at least one line of output. This is not necessarily the
data passed in. It may be data queued from a prior call to process(). If the internal buffer is full, more than 1 line will be output.
process() assumes that the a proper amount of indentation has already been output. It won't write any further indentation before the 1st line. If more than 1 line is written due to buffer constraints, the lines following the first will be indented by this method, though.
No \n is written by this method after the last line that is written.
Definition at line 2338 of file OptionParser.h.
Writes a single line of output from the buffer to
write.
Definition at line 2284 of file OptionParser.h.
Must be a power of 2 minus 1.
Definition at line 2214 of file OptionParser.h.
Ring buffer for data component of pair (data, length).
Definition at line 2222 of file OptionParser.h.
index for next write
Definition at line 2234 of file OptionParser.h.
Ring buffer for length component of pair (data, length).
Definition at line 2218 of file OptionParser.h.
index for next read - 1 (i.e.
increment tail BEFORE read)
Definition at line 2235 of file OptionParser.h.
The width of the column to line wrap.
Definition at line 2233 of file OptionParser.h.
Multiple methods of LineWrapper may decide to flush part of the buffer to free up space.
The contract of process() says that only 1 line is output. So this variable is used to track whether something has output a line. It is reset at the beginning of process() and checked at the end to decide if output has already occurred or is still needed.
Definition at line 2244 of file OptionParser.h.
The indentation of the column to which the LineBuffer outputs.
LineBuffer assumes that the indentation has already been written when process() is called, so this value is only used when a buffer flush requires writing additional lines of output.
Definition at line 2229 of file OptionParser.h. | https://root.cern/doc/master/classROOT_1_1option_1_1PrintUsageImplementation_1_1LineWrapper.html | CC-MAIN-2022-27 | refinedweb | 526 | 69.38 |
I've never seen anything that states arcpy should/must be imported first in order to not override other system modules. I only skimmed this document but didn't see anything specific, although their examples tend to imply it. However if you do a import-from on datetime BEFORE importing arcpy, then you're datetime import will be destroyed:
>>> from datetime import datetime
>>> datetime.now()
datetime.datetime(2016, 7, 14, 12, 10, 12, 433000)
>>> import arcpy
>>> datetime.now()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'now'
>>>
Either import datetime after arcpy or use the import-from-as syntax and give datetime an alias.
People had better scrounge around in their __init__.py files.
Perhaps the import should check for the existence in the namespace at least or use names that are unlikely to occur.
c:\\arcpro\\resources\\arcpy\\arcpy\\__init__.py....
import arcpy.time as time # ????
#how about, _time or thyme or time_ or about_ or tImE
import time, math, sys
from datetime import datetime
map(id, [time, math, sys, datetime])
[48738160, 57747920, 47497264, 1699354320]
import arcpy
map(id, [time, math, sys, datetime])
[48738160, 57747920, 47497264, 57866672]
The only ID that changes is datetime, so I'm not sure if that's actually the case. But we can look further into it as well.
Clinton Dow Was this bug resolved and at what ArcGIS version? It would be great to know. I just ran into it on ArcGIS 10.4.1 and lost a few hours trying to figure out what was happening.
# ---- python 3.10, arcpy 2.6 beta 2
import time, math, sys
from datetime import datetime
list(map(id, [time, math, sys, datetime]))
[1908941284840, 1908942659400, 1908930535160, 1381901040]
import arcpy
list(map(id, [time, math, sys, datetime]))
[1908941284840, 1908942659400, 1908930535160, 1381901040]
# ---- looks good
Thanks for the info! Would you know at what version of ArcGIS this bug was fixed? In any case, I'll endeavor to upgrade to the latest version.
Not sure, but I think shortly after it was discovered. I don't remember it being an issue for a few years
I just experienced this issue on ArcGIS Pro 2.5.2 (i.e. Python v 3). I only discovered it after getting the "now()" error and then manually moving my "from datetime import datetime" statement until i figure out it was the arcpy import that was clobbering it. So maybe not fixed, unless i'm doing something wrong?
hmmmm. I always import arcpy last
from datetime import datetime
n = datetime.now()
n
datetime.datetime(2020, 9, 17, 22, 7, 43, 827042)
import arcpy
n1 = datetime.now()
n1
datetime.datetime(2020, 9, 17, 22, 8, 0, 770167)
So slight wrinkle. It doesn't have the issue when you're using the interactive python window in Pro, but it DOES have the issue when using in a standalone script. I'm using the propy.bat to run the script from a windows scheduled task.
As a suggestion, I rarely import arcpy If I need something from the arcpy stable, I usually narrow down the import to the area that I need. The folder structure can be found in your install base folder
C:\arc_pro\Resources\ArcPy\arcpy where arc_pro is my install folder.
Some things like the arcgis module and the arcgisscripting module can be found in site-packages
C:\arc_pro\bin\Python\envs\arcgispro-py3\Lib\site-packages\arcgisscripting
So a blanket import of arcpy isn't recommended unless you need to access a wide variety of things from it. | https://community.esri.com/t5/python-questions/import-arcpy-tramples-datetime-import/m-p/288339 | CC-MAIN-2021-04 | refinedweb | 594 | 64.1 |
import "github.com/mholt/caddy/caddyhttp/httpserver"
Package httpserver implements an HTTP server on top of Caddy.
condition.go error.go https.go logger.go middleware.go mitm.go path.go plugin.go recorder.go replacer.go responsewriterwrapper.go roller.go server.go siteconfig.go tplcontext.go vhosttrie.go
const ( // ReplacerCtxKey is the context key for a per-request replacer. ReplacerCtxKey caddy.CtxKey = "replacer" //" )
OriginalURLCtxKey is the key for accessing the original, incoming URL on an HTTP request. )
These "soft defaults" are configurable by command line flags, etc..
ErrMaxBytesExceeded is the error returned by MaxBytesReader when the request body exceeds the limit imposed
TemplateFuncs contains user-defined functions for execution in templates..
DefaultErrorFunc responds to an HTTP request with a simple description of the specified HTTP status code.
func IfMatcherKeyword(c *caddy.Controller) bool
IfMatcherKeyword checks if the next value in the dispenser is a keyword for 'if' config block. If true, remaining arguments in the dispenser are cleared to keep the dispenser valid for use..
IsLogRollerSubdirective is true if the subdirective is for the log roller.
ParseRoller parses roller contents out of.
SafePath joins siteRoot and reqPath and converts it to a path that can be used to access a path on the local disk. It ensures the path does not traverse outside of the site root.
If opening a file, use http.Dir instead.
SameNext does a pointer comparison between next1 and next2.
Used primarily for testing but needs to be exported so plugins can use this as a convenience.(w http.ResponseWriter, r *http.Request)
WriteSiteNotFound writes appropriate error code to w, signaling that requested host is not served by Caddy on a given port.
func WriteTextResponse(w http.ResponseWriter, status int, body string)
WriteTextResponse writes body with code status to w. The body will be interpreted as plain text.
Address represents a site address. It contains the original input value, and the component parts of an address. The component parts may be updated to the correct values as setup proceeds, but the original value should never be changed.
The Host field must be in a normalized form.
Key is similar to String, just replaces scheme and host values with modified values. Unlike String it doesn't add anything default (scheme, port, etc)
Normalize normalizes URL: turn scheme and host names into lower case
String returns a human-friendly print of the address.
VHost returns a sensible concatenation of Host:Port/Path from a. It's basically the a.Original but without the scheme.
type ConfigSelector []HandlerConfig
ConfigSelector selects a configuration.
func (c ConfigSelector) Select(r *http.Request) (config HandlerConfig)
Select selects a Config. This chooses the config with the longest length.
type Context struct { Root http.FileSystem Req *http.Request URL *url.URL Args []interface{} // defined by arguments to .Include // contains filtered or unexported fields }
Context is the context with which Caddy templates are executed.
NewContextWithHeader creates a context with given response header.
To plugin developer: The returned context's exported fileds remain empty, you should then initialize them if you want.
AddLink adds a link header in response see
Cookie gets the value of a cookie with name name.
Env gets a map of the environment variables.
Ext returns the suffix beginning at the final dot in the final slash-separated element of the pathStr (or in other words, the file extension).
Files reads and returns a slice of names from the given directory relative to the root of Context c.
Header gets the value of a request header with field name.
Host returns the hostname portion of the Host header from the HTTP request.
Hostname gets the (remote) hostname of the client making the request.
IP gets the (remote) IP address of the client making the request.
Include returns the contents of filename relative to the site root.
IsMITM returns true if it seems likely that the TLS connection is being intercepted.
Join is a pass-through to strings.Join. It will join the first argument slice with the separator in the second argument and return the result.
Map will convert the arguments into a map. It expects alternating string keys and values. This is useful for building more complicated data structures if you are using subtemplates or things like that.
Markdown returns the HTML contents of the markdown contained in filename (relative to the site root).
Method returns the method (GET, POST, etc.) of the request.
Now returns the current timestamp in the specified format.
NowDate returns the current date/time that can be used in other time functions.
PathMatches returns true if the path portion of the request URL matches pattern.
Port returns the port portion of the Host header if specified.
RandomString generates a random string of random length given length bounds. Thanks to for the clever technique that is fairly fast, secure, and maintains proper distributions over the dictionary.
Replace replaces instances of find in input with replacement.
ServerIP gets the (local) IP address of the server. TODO: The bind directive should be honored in this method (see PR #1474).
Slice will convert the given arguments into a slice.
Split is a pass-through to strings.Split. It will split the first argument at each instance of the separator and return a slice of strings.
StripExt returns the input string without the extension, which is the suffix starting with the final '.' character but not before the final path separator ('/') character. If there is no extension, the whole input is returned.
StripHTML returns s without HTML tags. It is fairly naive but works with most valid HTML inputs.
Returns either TLS protocol version if TLS used or empty string otherwise
ToLower will convert the given string to lower case.
ToUpper will convert the given string to upper case.
Truncate truncates the input string to the given length. If length is negative, it returns that many characters starting from the end of the string. If the absolute value of length is greater than len(input), the whole input is returned.
URI returns the raw, unprocessed request URI (including query string and hash) obtained directly from the Request-Line of the HTTP request.
type HTTPInterfaces interface { http.ResponseWriter http.Pusher http.Flusher http.CloseNotifier http.Hijacker }
HTTPInterfaces mix all the interfaces that middleware ResponseWriters need to support. interface { RequestMatcher BasePath() string }
HandlerConfig is a middleware configuration. This makes it possible for middlewares to have a common configuration interface.
TODO The long term plan is to get all middleware implement this interface for configurations.
HandlerFunc is a convenience type like http.HandlerFunc, except ServeHTTP returns a status code and an error. See Handler documentation for more information.
func (f HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error)
ServeHTTP implements the Handler interface.
type IfMatcher struct { Enabled bool // if true, matcher has been configured; otherwise it's no-op // contains filtered or unexported fields }
IfMatcher is a RequestMatcher for 'if' conditions.
And returns true if all conditions in m are true.
Match satisfies RequestMatcher interface. It returns true if the conditions in m are true.
Or returns true if any of the conditions in m is true.
Limits specify size limit of request's header and body.
ListenerMiddleware is similar to the Middleware type, except it chains one net.Listener to the next.
type LogRoller struct { Disabled bool Filename string MaxSize int MaxAge int MaxBackups int Compress bool LocalTime bool }
LogRoller implements a type that provides a rolling logger.
DefaultLogRoller will roll logs by default. struct { Output string *log.Logger Roller *LogRoller V4ipMask net.IPMask V6ipMask net.IPMask IPMaskExists bool Exceptions []string // contains filtered or unexported fields }
Logger is shared between errors and log plugins and supports both logging to a file (with an optional file roller), local and remote syslog servers.
NewTestLogger creates logger suitable for testing purposes
func (l *Logger) Attach(controller *caddy.Controller)
Attach binds logger Start and Close functions to controller's OnStartup and OnShutdown hooks.
Close closes open log files or connections to syslog.
Printf wraps underlying logger with mutex
Println wraps underlying logger with mutex
ShouldLog returns true if the path is not exempted from being logged (i.e. it is not found in l.Exceptions).
Start initializes logger opening files or local/remote syslog connections
Middleware is the middle layer which represents the traditional idea of middleware: it chains one Handler to the next by being passed the next Handler in the chain.
type NonCloseNotifierError struct { // underlying type which doesn't implement CloseNotify Underlying interface{} }
NonCloseNotifierError is more descriptive error caused by a non closeNotifier
func (c NonCloseNotifierError) Error() string
Implement Error
type NonFlusherError struct { // underlying type which doesn't implement Flush Underlying interface{} }
NonFlusherError is more descriptive error caused by a non flusher
func (f NonFlusherError) Error() string
Implement Error
type NonHijackerError struct { // underlying type which doesn't implement Hijack Underlying interface{} }
NonHijackerError is more descriptive error caused by a non hijacker
func (h NonHijackerError) Error() string
Implement Error
type NonPusherError struct { // underlying type which doesn't implement pusher Underlying interface{} }
NonPusherError is more descriptive error caused by a non pusher
func (c NonPusherError) Error() string
Implement Error
Path represents a URI path. It should usually be set to the value of a request path..
PathLimit is a mapping from a site's path to its corresponding maximum request body size (in bytes)
PathMatcher is a Path RequestMatcher.
func (p PathMatcher) Match(r *http.Request) bool
Match satisfies RequestMatcher.).
RequestMatcher checks to see if current request should be handled by underlying handler.
func MergeRequestMatchers(matchers ...RequestMatcher) RequestMatcher
MergeRequestMatchers merges multiple RequestMatchers into one. This allows a middleware to use multiple RequestMatchers.
func SetupIfMatcher(controller *caddy.Controller) (RequestMatcher, error)
SetupIfMatcher parses `if` or `if_op` in the current dispenser block. It returns a RequestMatcher and an error if (rb *ResponseBuffer) Buffered() bool
Buffered returns whether rb has decided to buffer the response.
func (rb *ResponseBuffer) CopyHeader()
CopyHeader copies the buffered header in rb to the ResponseWriter, but it does not write the header out.
func (rb *ResponseBuffer) Header() http.Header
Header returns the response header (rb *ResponseBuffer) StatusCodeWriter(w http.ResponseWriter) http.ResponseWriter
StatusCodeWriter returns an http.ResponseWriter that always writes the status code stored in rb from when a response was buffered to it.
func (rb *ResponseBuffer) Write(buf []byte) (int, error)
Write writes buf to rb.Buffer if buffering, otherwise to the ResponseWriter directly if streaming.
func (rb *ResponseBuffer) WriteHeader(status int)
WriteHeader calls shouldBuffer to decide whether the upcoming body should be buffered, and then writes the header to the response. (r *ResponseRecorder) Size() int
Size returns the size of the recorded response body.
func (r *ResponseRecorder) Status() int
Status returns the recorded response status code.
func (r *ResponseRecorder) Write(buf []byte) (int, error)
Write is a wrapper that records the size of the body that gets written.
func (r *ResponseRecorder) WriteHeader(status int)
WriteHeader records the status code and calls the underlying ResponseWriter's WriteHeader method.
type ResponseWriterWrapper struct { http.ResponseWriter }
ResponseWriterWrapper wrappers underlying ResponseWriter and inherits its Hijacker/Pusher/CloseNotifier/Flusher as well. (rww *ResponseWriterWrapper) Flush()
Flush implements http.Flusher. It simply wraps the underlying ResponseWriter's Flush method if there is one, or panics.
func (rww *ResponseWriterWrapper) Hijack() (net.Conn, *bufio.ReadWriter, error)
Hijack implements http.Hijacker. It simply wraps the underlying ResponseWriter's Hijack method if there is one, or returns an error.
func (rww *ResponseWriterWrapper) Push(target string, opts *http.PushOptions) error
Push implements http.Pusher. It just inherits the underlying ResponseWriter's Push method. It panics if the underlying ResponseWriter is not a Pusher.
Server is the HTTP server implementation.
func NewServer(addr string, group []*SiteConfig) (*Server, error)
NewServer creates a new Server instance that will listen on addr and will serve the sites configured in group.
Address returns the address s was assigned to listen on.
Listen creates an active listener for s that can be used to serve requests.
func (s *Server) ListenPacket() (net.PacketConn, error)
ListenPacket creates udp connection for QUIC if it is enabled,
OnStartupComplete lists the sites served by this server and any relevant information, assuming caddy.Quiet == false.
Serve serves requests on ln. It blocks until ln is closed.
ServeHTTP is the entry point of all HTTP requests.
func (s *Server) ServePacket(pc net.PacketConn) error
ServePacket serves QUIC requests on pc until it is closed.
Stop stops s gracefully (or forcefully after timeout) and closes its listener.
WrapListener wraps ln in the listener middlewares configured for this server.
type SiteConfig struct { // The address of the site Addr Address // The list of viable index page names of the site IndexPages []string // The hostname to bind listener to; // defaults to Addr.Host ListenHost string // TLS configuration TLS *caddytls.Config // If true, the Host header in the HTTP request must // match the SNI value in the TLS handshake (if any). // This should be enabled whenever a site relies on // TLS client authentication, for example; or any time // you want to enforce that THIS site's TLS config // is used and not the TLS config of any other site // on the same listener. TODO: Check how relevant this // is with TLS 1.3. StrictHostMatching bool //(c *caddy.Controller) *SiteConfig
GetConfig gets the SiteConfig that corresponds to c. If none exist (should only happen in tests), then a new, empty one will be created.
func (s *SiteConfig) AddListenerMiddleware(l ListenerMiddleware)
AddListenerMiddleware adds a listener middleware to a site's listenerMiddleware stack.
func (s *SiteConfig) AddMiddleware(m Middleware)
AddMiddleware adds a middleware to a site's middleware stack.
func (s SiteConfig) Host() string
Host returns s.Addr.Host.
func (s SiteConfig) ListenerMiddleware() []ListenerMiddleware
ListenerMiddleware returns s.listenerMiddleware
func (s SiteConfig) Middleware() []Middleware
Middleware returns s.middleware (useful for tests).
func (s SiteConfig) Port() string
Port returns s.Addr.Port.
func (s SiteConfig) TLSConfig() *caddytls.Config
TLSConfig returns s.TLS. associated bool field is true, then the duration value should be treated literally (i.e. a zero-value duration would mean "no timeout"). If false, the duration was left unset, so a zero-value duration would mean to use a default value (even if default is non-zero).
Package httpserver imports 39 packages (graph) and is imported by 2817 packages. Updated 2020-01-18. Refresh now. Tools for package owners. | https://godoc.org/github.com/mholt/caddy/caddyhttp/httpserver | CC-MAIN-2020-10 | refinedweb | 2,362 | 50.63 |
Introduction
There are many tutorials on the web to get one started using D3. Links to some of these works will follow later in this article. While they are all wonderful (and I thank each author for getting me over the steep D3 learning curve), most of these tutorials assume you know what D3 is, know you want to use it, and jump into the heart of D3 (data joins), which is kind of mind blowing and hard to wrap your head around.
Being on the flip-side of the learning curve, I look back at these tutorials and understand why the learning curve was so steep: D3 is not what you think it is (i.e, it’s not an SVG library), but is exactly as its name implies, a tool to drive data through your documents. D3’s heart is a mechanism to bind data to the DOM, including tools for handling deltas in a changing stream of data, which makes it a powerful tool for managing, in particular, visualizations. And that means dynamic, interactive SVG.
But even now I’m getting ahead of myself. I’m going to start from the beginning…
My Assignment
Recently I was assigned a project to build a highly interactive chart. A non-disclosure prevents me from sharing a screen shot, but suffice it to say, there’s lots of lines to plot, any of which can be turned on or off via a complex legend, there’s lots of zooming and panning of time-series data, and alerts appear on the chart, which, when clicked, show popups with detailed data.
A previous phase of the work had a much simpler graph (one line per graph) built with nvd3, a library built on D3. It was assumed I would continue to use nvd3 (or similar library, like rickshaw) for this complex chart, but was allowed time to explore other possibilities, including raw D3.
I took a step even further back…
<canvas> or <svg>
In modern browsers (and by this I mean recent firefox, chrome, safari, and IE9+), there are two standards for drawing on the page:
<canvas> and
<svg>. Did it make sense to consider
<canvas> for this project?
<canvas>
Let’s look at a simple canvas example:
The above is rendered with this HTML:
<body> <div class="title"> <h1>Canvas Example</h1> </div> <canvas id="mycanvas" width="1000" height="300"></canvas> <script src="canvas.js"></script> </body>
You will notice the
<canvas> tag: it has an
id and specifies a width and height, setting the canvas to 1000×300. The canvas tag supports HTML global and event attributes, but otherwise has only two attributes,
width and
height (which default to 300×150). So, where do the circles come from? A canvas specifies a two-dimensional space within the document to draw 2d graphics with a javascript API.
The loaded script draws the circles:
function draw() { /* Canvas example - draw two circles */ // get the canvas element and 2d context var canvas = document.getElementById("mycanvas"); var ctx = canvas.getContext("2d"); // draw a blue circle ctx.fillStyle = "blue"; ctx.beginPath(); ctx.arc(250, 150, 100, 0, Math.PI*2); ctx.fill(); // craw a red circle ctx.fillStyle = "red"; ctx.beginPath(); ctx.arc(750, 150, 100, 0, Math.PI*2); ctx.fill(); } draw();
The Canvas API is very simple to use. The details of the above are beyond the scope of this document, but you can quickly scan the code to see a 2d context is retrieved (by referencing the ID of the canvas), and two arcs are drawn, one blue and one red. See MDN’s wonderful documentation for API details and tutorials.
A few take-aways:
- A canvas creates a bitmap image. There are no objects created or retained. Once drawn, its just bits on the canvas. To create a “circle” as an object, to be later manipulated, a separate data structure would need to be managed.
- Because no object exists, if we wanted to change the red circle to green, we’d have to redraw the canvas.
- Again, because there are no objects within the canvas, interacting with the bitmap is difficult. How do we know if a user clicks on the red circle? We would have to maintain our own mapping of objects to their locations so mouse coordinates could be targeted. Painful!
It would appear we could draw any chart easily with canvas, but manipulating it and interacting with it is very, very difficult.
<svg>
Let’s look at the same graphic, but this time using SVG:
The above is rendered with this HTML:
<body> <div class="title"> <h1>SVG Example</h1> </div> <svg width="1000" height="300"> <circle id="c1" cx="250" cy="150" r="100" fill="blue"></circle> <circle id="c2" cx="750" cy="150" r="100" fill="red"></circle> </svg> </body>
No javascript! The "canvas" and objects within are fully represented within the DOM. Instead of bits within a bitmap, we have actual circle objects with attributes that define the circle. This means we can manipulate and interact with the objects of our chart after they have been drawn…
To change the red circle to green:
var c2 = document.getElementById('c2'); c2.setAttribute('fill', 'green');
To move the (now) green circle to the left:
c2.setAttribute('cx', 500);
To make the circle tiny:
c2.setAttribute('r', 25);
And to add an event listener:
c2.addEventListener('click', function() { alert('Tiny green circle clicked!'); });
Clearly, SVG provides a higher order of abstraction when compared to canvas’ bitmap images. (While I don’t know, one can imagine that SVG is implemented with the underlying canvas technology of a browser.)
At this point of understanding, it was clear to me that SVG was, in fact, the proper technology to use for a complex chart requiring manipulation and interactivity after it was drawn.
A Basic Knowledge of SVG Is Required
As stated above, D3 is not an SVG library, per se. Jumping into D3 (for purposes of creating visualizations) without any prior knowledge of SVG will make the learning curve all the more steeper.
There are many, many fine SVG tutorials on the web. These two are great:
Javascript Libraries
Having decided SVG was the correct technology, which javascript library was I going to use? Searching the web for "javascript svg" you will discover two classes of libraries: 1) libraries that map svg elements to functions (e.g, to create a circle, you call a circle() function), which I think of as literal libraries, and 2) DOM manipulation libraries, lead by D3 and its offspring.
Literal Libraries
For years, the defacto standard for javascript manipulation of SVG has been Raphaël. In no small part, because Raphaël’s higher order functions support older IE browsers (back to IE6), falling back to using VML for those browsers. Write once, run anywhere.
You can see the literalness of SVG in javascript code with this snippet:
// Creates canvas 320 x");
Other libraries of this class include:
- snap. Snap was written entirely from scratch by the author of Raphaël, designed specifically for modern browsers, allowing the library to take advantage of modern features.
- svg.js, jQuery SVG. These libraries (and others) have similar look and feel to Raphaël and snap: map svg elements to objects, manipulating attributes via methods on the objects. Each supports advanced manipulations (animations) and/or graphing via higher-order classes and methods.
D3 and Its Progeny
Unlike the above libraries, D3 does not map svg elements to javascript objects. You will not find anywhere in its API a Circle object you can instantiate with getter and setter methods for its radius. (Also, unlike, say, Raphaël, D3 makes no effort to support older browsers.)
It is, first and foremost, a framework for working with data:
- It augments javascript with objects managing higher order data structures than are presently provided by implementations of ECMAScript 5, such as maps, sets, and nests.
- It provides many functions over many domains (geography, geometry, layouts, scales, time), implementing algorithms useful in visualization.
- Most compellingly, it provides a unique method of binding data to DOM elements, which, when applied to SVG, creates dynamic, interactive charts and visualizations.
Risking sounding like a broken record, I cannot stress enough that D3 is not what you think it is.
Whet Your Appetite
There are many amazing examples of D3 on the web. A rather large collection can be found at the official D3 Gallery. Here are three of my favorites (but I caution you: hours of your life will be lost playing with these!):
- Epicyclic Gearing
- Collision Detection
- Drag and Drop, Zoomable, Panning, Collapsible Tree with auto-sizing
Many, MANY Libraries Based On D3
D3 has a reputation for having a steep learning curve. Whether it’s because of a mismatch of expectations and reality (as this tutorial suggests, at least in part), or it is actually difficult to grok, many projects exist to ease the supposed D3 pain and provide libraries for specialized visualization needs.
This blog post has a long list of projects that package D3 for specific visualization domains, from visualizing data from specific data stores to generalized charting tools.
At the very top of the post is a list of many fine D3 tutorials. My personal favorites were Scott Murray’s tutorials and his book. Each of the listed tutorials is worth a read, but each suffers from the jump-in-head-first perspective I mentioned at the start of this article. They will be great resources after you wrap your head around what D3 is not, and have an idea of what it actually is!
Why, in the end, I did not choose nvd3 or rickshaw…
As mentioned above, both nvd3 and rickshaw are general purpose charting libraries, so why not use one of these tools? In brief: my charting project was just too specialized and complex and I realized I would be fighting the toolkits from beginning to end, and would have to use D3 anyway to get my custom components in their charts. Could it be done? Sure. Would it have saved me time? Doubtful.
While wrestling over the decision, one important factor was the availability of descent documentation. D3 has very good documentation. Both nvd3 and rickshaw have
<rant>NO API DOCUMENTATION AT ALL
</rant>. Even their source code repositories are shockingly absent of any internal comments. Ugh.
So, after writing a simple, sample application in D3, nvd3 and rickshaw, and realized D3’s learning curve was not as steep as I first feared, I willingly plunged in and have been very happy with that decision.
D3 API Tour
One last thing before plunging into a sample application. Take a quick look at the API Documentation. I don’t mean read it (that will come in time), but just scroll down the page to get a sense of the immense scope of the API. That’s a LOT of functionality packed into 151K (minified).
Two things to point out:
- You will notice a lot of functions related to selections. Think jQuery: much of the functionality in jQuery is supplied by D3. Strange? At first, yes! And this is where I think many newbies to D3 stumble, but this is the heart of D3: manipulating data via selections.
- You may notice a number of functions in the
d3.svgnamespace. Do not be fooled! These are not what you think they are!! They do not draw circles or rectangles. They are functions that generate data to be used with your selections and bound data.
Dots! A D3 Sample Application
Finally. Actual D3 code!
There is a live demo of this application hosted over at bl.ocks.org.
At the bottom of
index.html, you will see this javascript code:
dots = d3.sample_dots({width:600, height:300}); d3.select("#dots").call(dots);
The first line creates a function with the specified configuration (setting the width of the svg to 600x300px). This function is then called on the selection
"#dots" (a div in the DOM). The second line is identical to this:
dots(d3.select("#dots"));
Using the
.call() function is idiomatic for D3 and will become obvious why it is so, as you become more familiar with the API.
The application paints puddles of dots: for each iteration, eight to sixty-four randomized dots (color, location, radius) are generated and animated on the canvas. If a previous group of dots already exists, they evaporate and are removed as the new batch forms.
You can interact with the dots: hovering your mouse over a dot while it exists will show a tooltip with details about the color.
At the bottom right of the iframe, there is a link, Open in a new window. If you do this, then open a developer console, you can interact with the dots via javascript:
dots.stop() // stops the animation dots.paint() // paints one iteration, then stops dots.go() // restarts the animation
go() calls
paint() and then sets a timer to call itself in five seconds.
stop() clears the timer. The heart of the application is the
paint() function. Let’s break it down:
dots.paint = function() { /* paint a new set of dots */ var update, data = fetchData(); // get an update selection (probably empty) after binding to new // set of data. See: update = vis.selectAll('circle') .data(data, dataKey);
We declare a few variables.
data holds a randomized selection of dots. Each dot is an object of the form:
{ x: <x-coord of center> y: <y-coord of center> r: <radius> c: <color object> }
Each value is randomized. The color object contains properties of the color, its name, hex, and RGB values. (BTW, kudos to jjdelc for the crayola colors!)
update is set to the selection of all
<circle> elements in the svg. (
vis is set at initialization to a d3.selection of the
<svg> element inserted into the DOM.) And then the data is bound to this selection with the
data() function.
If there is one thing you should spend time grokking, it’s understanding data binding and D3’s concept of a join (not unlike an SQL join). When you call
data() on a selection, it binds the data (an array) to the selection, one datum per element in the selection. Based on the existence of data previously bound to the same selection,
data() creates three selections:
- update – the update selection: those elements that were previously bound to the same data, i.e, for those elements that already exist in the DOM and are bound to the same data. Typically, elements of this selection will have attributes updated.
- enter – the enter selection: those elements that are new, i.e, we have data for elements that do not yet exist in the DOM. Typically, elements will be added to the DOM based on this selection.
- exit – the exit selection: those elements that are old, i.e, we have preexisting elements for which there is no data. Typically, these elements will be removed from the DOM.
The author of D3, Mike Bostock, has written a wonderful article explaining this join process, Thinking with Joins. READ IT. Read it again. Seriously, grokking this pays dividends!
The
data() method returns the update selection. Hanging off the update selection are the enter and exit selections, each returned by a function of the same name.
// new dots update.enter() .append('circle') .attr('r', 0) .attr('opacity', 0.6) .attr('fill', function(d){return d.c.hex;}) .on('mouseover', tip.show) // for mouse hovering over dots .on('mouseout', tip.hide) .transition() // animate radius growing .duration(4500)// over 4.5 seconds .attr('r', function(d) {return d.r;});
The next statement, a long chain of function calls (again, very idiomatic of D3 programming), first calls
enter(), returning a selection of circles that do not exist. For each, we append a circle, setting several attributes. In some cases the attributes values are constant:
.attr('r', 0)
The above sets the radius to zero. Other values are functions:
.attr('fill', function(d){return d.c.hex;})
The above sets the fill based on the data for the current element being added. If you recall, each datum was an object that had a
c property, the color object, and we’re using the hex value to set the fill color of the circle. Dynamic values based on data bound to the element!
After setting attributes we attach a few event handlers to manage the tooltips, then we called:
.transition() // animate radius growing .duration(4500)// over 4.5 seconds .attr('r', function(d) {return d.r;});
This creates a transition (an animation) lasting 4.5 seconds over which radius will increase (from zero) to the value specified by the object bound to this element.
update // place at x,y .attr('cx', function(d) { return d.x; }) .attr('cy', function(d) { return d.y; });
The next statement uses the update selection. It should be noted that when using the
append() method of an enter selection, the newly appended elements are automatically added to the update selection. This has immense impact on the code you write and you will find yourself using the idiomatic update pattern throughout your code. Continuing with the above, the elements added (or already existing) have their center points set, based on the data.
update // for exiting dots, transition radius to zero, then remove // from DOM .exit() .transition() .duration(4500) .attr('r', 0) .remove(); };
The final statement of the function uses the exit selection, and, mirroring the transition of the newly created circles, old circles reduce their radius to zero over 4.5 seconds and then are removed from the DOM.
Even in this simple application, there is a lot to wrap your head around. Focus on understanding data joins and the update pattern. They are the heart and soul of D3 programming.
Not Just SVG
As a final beat-this-point-to-death (that D3 is not strictly an SVG library), I leave you with this demonstration. It creates a table based on data. Not a lick of SVG. It’s fully annotated and I think worth understanding.
This article is not so much a tutorial. More, a missive: what SVG is and is not, and why you might want to use it and, assuming you do, what to pay attention to when you start.
From here, I’d suggest reviewing the tutorials listed above.
Meanwhile, I’ll start working on my next D3 post, exploring some of those mysterious
d3.svg.* functions.
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. | https://artandlogic.com/2015/06/d3-data-driven-documents/?shared=email&msg=fail | CC-MAIN-2021-43 | refinedweb | 3,085 | 64.91 |
Introduction
In this lesson, you will be introduced to some basic math concepts, and their corresponding MATLAB data structures. You will see how these data structures can be 1) created in MATLAB, and how they can be 2) index and 3) used.
MATLAB, the MATrix LABoratory
Three fundamental concepts in MATLAB, and in linear algebra, are scalars, vectors and matrices.
A scalar is simply just a fancy word for a number (a single value).
A vector is an ordered list of numbers (one-dimensional). In MATLAB they can be represented as a row-vector or a column-vector.
A matrix is a rectangular array of numbers (multi-dimensional). In MATLAB, a two-dimensional matrix is defined by its number of rows and columns.
Note: Though matrices can have more than two-dimensions, in this lesson we work only with two-dimensional matrices. If you need to work with matrices that have more than two-dimensions, you can refer to the help information of MATLAB.
In MATLAB, and in linear algebra, numeric objects can be categorized simply as matrix: Both scalars and vectors can be considered a special type of matrix. For example a scalar is a matrix with a row and column dimension of one (1-by-1 matrix). And a vector is a one-dimensional matrix: one row
and n-number of columns, or n-number of rows and one column.
All calculations in MATLAB are done with "matrices". Hence the name MATrix LABoratory.
Creating Matrices in MATLAB
In MATLAB matricies are defined inside a pair of square braces ([]). Punctuation marks of a comma (,), and semicolon (;) are used as a row separator and column separator, respectfully.
Note: you can also use a space as a row separator, and a carriage return (the enter key) as a column separator as well.
Below are examples of how a scalar, and a vector can be created in MATLAB.
my_scalar = 3.1415
my_scalar =
my_vector1 = [1, 5, 7]
my_vector1 =
my_vector2 = [1; 5; 7]
my_vector2 =
You will note that one vector is represented as a row vector (my_vector1), and the other as a column vector (my_vector2).
Now you know how to create scalars and vectors, but what about a two dimensional matrix? For example, how do we create a matrix called my_matrix with the numbers 8, 12, and 19 in the first row, 7, 3, 2 in the second row, 12, 4, 23 in the third row, and 8, 1, 1, in the fourth row?
my_matrix = [8, 12, 19; 7, 3, 2; 12, 4, 23; 8, 1, 1]
my_matrix =
With the above line of code, my_matrix is now defined as the 4-by-3 matrix (4 rows and 3 columns).
You can also combine different vectors and matrices together to define a new matrix. But remember that the output needs to be a valid rectangular matrix. Note that the row separator and column separator function in the same way.
row_vector1 = [1 2 3]
row_vector1 =
row_vector2 = [3 2 1]
row_vector2 =
matrix_from_row_vec = [row_vector1 ; row_vector2]
matrix_from_row_vec =
column_vector1 = [1;3]
column_vector1 =
column_vector2 = [2;8]
column_vector1 =
matrix_from_col_vec = [column_vector1 column_vector2]
matrix_from_col_vec =
combined_matrix = [my_matrix, my_matrix]
combined_matrix =
From these examples you can see how any type of matrix can be created using the square braces, in conjunction with the row and column separators. And with this you can create the data set needed to compute with or visualize with.
More than not, the type of data that you will work with will be vectors. For example you may be given the temperature data for each hour of the day (a vector with 24 elements), and need to plot the data against time. But how would you create the time data? You could create it manually,
time = [0, 100, 200, 300, 400, ..., 1900, 2000, 2100, 2200, 2300];
or you could use the colon operator. The colon operator allows you to create an incremental vector of regularly spaced points by specifying:
start_value:increment:stop_value
In this case,
time = 0:100:2300
Instead of an incremental value you can also specify a decrement as well. The following line of code would create a time vector from 2300 to zero with decrements of a 100.
time_dec = 2300:-100:0
Indexing Into a Matrix
Once a vector or a matrix is created you might needed to extract only a subset of the data, and this is done through indexing.
To index into an ordered list, a vector, you need to know where the order starts. In a row vector the left most element has the index of one. In a column vector the top most element has the index of one.
Let’s look at the example of my_vector1 and my_vector2 and see how we can index into its values.
my_vector1 = [1 5 7]
my_vector1 =
my_vector2 = [1; 5; 7]
my_vector2 =
my_vector1(1)
ans =
my_vector2(2)
ans =
my_vector1(3)
ans =
my_vector2(1)
ans =
my_vector2(3)
ans =
The process is much the same for a two-dimensional matrix. The only difference is that you would specify the row and column index rather than the single index, as we did for the vectors.
To access the value of 4 you would type in
my_matrix(3,2)
ans =
Note: The row number is first, followed by the column number.
You can also extract any contiguous subset of a matrix, by referring to the row range and column range you want. For example, if mat is a matrix with 5 rows and 8 columns, then typing mat(2:4,4:7) would extract all elements in rows 2 to 4 and in columns 4 to 7. Here is
an example:
new_mat = mat(2:4,4:7)
You can change a number in a matrix by assigning to it:
new_mat
new_mat(2,3) = 1999
You should keep in mind that, since vectors are just kinds of matrices, all the operations you learned above for matrices can also be used for vectors. For example, you can change numbers stored in vectors as above. There are many other aspects of matrices and vectors that we have not gone into
here in this introductory lesson. We will go into some more advanced aspects of matrices and vectors in the core lessons, but you should also explore the MATLAB help texts on your own to learn more about how you can use and manipulate matrices in MATLAB.
Element-By-Element Operations and Matrix Operations
Before anything else, let us define what an element is: an element of a matrix is simply one of the numbers stored in the matrix.
For example, if you saw a sentence that said "a row vector of ten elements" or "a ten element row vector", then you would know that this just means a row vector that has ten numbers stored in it. Likewise, if you saw a sentence that said "the 8th element of the vector
V", then you would know that this just means the number stored at the 8th position of V (i.e., V(8)).
When reading MATLAB documentation you will often see the expression "element-by-element", and this has to do with operations that are performed on two matrices of the same size to get another, result vector of the same size. This just means that, to get the value of a particular element
in the result vector, you perform the operation on the corresponding (i.e., same position) elements in the two vectors.
For example, "element-by-element multiplication" of two vectors [1 2 3] and [4 5 6] would give you [4 10 18].
The element-by-element operators in MATLAB are as follows:
element-by-element multiplication: ".*"
element-by-element division: "./"
element-by-element addition: "+"
element-by-element subtraction: "-"
element-by-element exponentiation: ".^"
Here are some examples of using the element-by-element operators (notice that there is an error when trying to perform element-by-element operations when using a row vector and column vector together):
a
a =
b
b =
c
c =
d
d =
a .* b
ans =
a .* c
??? Error using ==> .*
Matrix dimensions must agree.
c .* d
ans =
a .^ b
ans =
c .^ d
ans =
An additional note about element-by-element operators is that you can use them with scalars (remember, that just means numbers!) and vectors together. For example, say you wanted to multiply every element of a vector by two; you could do that by performing element-by-element multiplication of
the number 2 with a vector:
a = [1 2 3 4 5 6]
a =
b = a .* 2
b =
And, you could similarly use ".^", "+", and "-" with a vector and scalar. Here are some examples:
c = a .^ 2
c =
d = a + 2
d =
e = a - 2
e =
You might wonder why the element-by-element multiplication and exponentiation operators have "." appended to the front of them, while the element-by-element addition and subtraction operators do not. The reason is that there are other kinds of multiplication, division, and exponentiation
operators for matrices, which are not element-by-element, that are denoted by "*" , "/"and "^".
This brings us to the other type of operations: matrix operations. Element-by-element operations allow us to compute things on an element-by-element basis, but matrix operations allow us to perform matrix-based computation.
For example, the multiplication of two matrices, represented by "*", performs a dot product of the two matrices. What the dot product does is that it first multiplies the corresponding elements (i.e., same position elements) of the two vectors, similar to what element-by-element multiplication
does, and then adds up all the results of these multiplications to get a single, final number as the answer. A simple example should make this clear:
a = [1 2 3]
a =
b = [4 ; 5 ; 6]
b =
a * b
ans =
To get the answer "32", what MATLAB did was first to perform the multiplications of the corresponding elements of the two vectors: "1*4 = 4", "2*5=10", and "3*6=18". Then, to get the final answer of "32", MATLAB added all these multiplications
together: "4+10+18=32".
Putting It All Together
Having gone through this section, you now know how to create your own matrices (using the square braces or the colon operator), index into the matrices, and compute with the matrices (element-by-element computations, and matrix-based computations).
Let’s now look at an example that uses these concepts. Let’s say that you are given the task of finding the solutions to the equation of a parabola (y=x^2). Where "x" is the range from -100 to 100. Once computed, we want to only look at the data from the range -2 to 2.
With what we know we could do the following:
inc = 1; % you can specify your own value of INC x = -100:inc:100; y =
x.^2; % compute the square of each element separately
inc = 1; % you can specify your own value of INC
x = -100:inc:100;
y =
x.^2; % compute the square of each element separately
Note: The above is an example of one of MATLAB's powerful features, vectorization: using a vector as an input to an equation, similar to how you can use a variable as input, and get another vector as output which has elements that are the values of the equation evaluated
at the numbers in the input vector.
Now, we need to locate the data points from -2 to 2. To do so, we need to know the length of "x", and index into both "x" and "y" at the right locations.
We can either look for a function which will return the length of a vector, or figure it out ourselves. Can you find the function for obtaining a vector’s length? Or are you figuring it out in your head?
len_x = length(x)
len_x =
midpoint_index = round(len_x/2)
midpoint_index =
new_x_range = x(midpoint_index-2:midpoint_index+2)
new_x_range =
new_y_range = y(midpoint_index-2:midpoint_index+2)
new_y_range =
Note: This is not the only way to do this example. You could have also found the range using Boolean indexing. Try searching the Help Browser on "Boolean".
Below is another example of vectorization.
input_points = [-pi : pi/8 : pi]
input_points =
Columns 1 through 7
-3.1416 -2.7489 -2.3562 -1.9635 -1.5708 -1.1781 -0.7854
Columns 8 through 14
-0.3927 0 0.3927 0.7854 1.1781 1.5708 1.9635
Columns 15 through 17
2.3562 2.7489 3.1416
sine_curve = 3*sin(5.*input_points)
sine_curve =
Columns 1 through 7
0.0000 -2.7716 2.1213 1.1481 -3.0000 1.1481 2.1213
Columns 8 through 14
-2.7716 0 2.7716 -2.1213 -1.1481 3.0000 -1.1481
Columns 15 through 17
-2.1213 2.7716 0.0000
Continue on to the next lesson.
See also: Simulink Tutorial | http://www.mathworks.com/academia/student_center/tutorials/performing_calculations.html | crawl-002 | refinedweb | 2,122 | 61.26 |
Ruby variables
In this part of the Ruby tutorial, we will examine variables in more detail.
A variable is a place to store data. Each variable is given a unique name. There are some naming conventions which apply to variable names. Variables hold objects. More precisely, they refer to a specific object located in computer memory. Each object is of certain data type. There are built-in data types and there are custom-built data types. Ruby belongs to the family of dynamic languages. Unlike strongly typed languages like Java, C or Pascal, dynamic languages do not declare a variable to be of certain data type. Instead of that, the interpreter determines the data type at the moment of the assignment. Variables in Ruby can contain different values and different types of values over time.
#!/usr/bin/ruby i = 5 puts i i = 7 puts i
The term variable comes from the fact that variables, unlike constants, can take different values over time. In the example above there is a variable called i. First it is assigned a value 5, later a different value 7.
Naming conventions
Ruby, like any other programming language, has some naming conventions for variable identifiers.
Ruby is a case sensitive language. It means that age and Age are two different variable names. Most languages are case sensitive. BASIC is an exception; it is a case insensitive language. While we can create different names by changing the case of the characters, this practice is not recommended.
#!/usr/bin/ruby i = 5 p i I = 7 p I
The code example defines two variables: I and i. They hold different values.
./case.rb 5 7
Output of the case.rb example.
Variable names in Ruby can be created from alphanumeric characters
and the underscore
_ character. A variable cannot begin with a number.
This makes it easier for the interpreter to distinguish a literal number
from a variable. Variable names cannot begin with a capital letter. If an
identifier begins with a capital letter, it is considered to be a constant in Ruby.
#!/usr/bin/ruby name = "Jane" placeOfBirth = "Bratislava" placeOfBirth = "Kosice" favorite_season = "autumn" n1 = 2 n2 = 4 n3 = 7 p name, placeOfBirth, favorite_season p n1, n2, n3
In this script, we show a few valid variable names.
Variable names should be meaningful. It is a good programming practice to choose descriptive names for variables. The programs are more readable then.
#!/usr/bin/ruby name = "Jane" place_of_birth = "Bratislava" occupation = "student" i = 5 while i > 0 do puts name i -= 1 end
The script shows three descriptive variable names. The place_of_birth is more descriptive to a programmer than e.g. pob. It is generally considered OK to choose simple variable names in loops.
Sigils
Variable identifiers can start with special characters also called sigils.
A sigil is a symbol attached to an identifier. Variable sigils in Ruby denote
variable scope. This is in contrast to Perl, where sigils denote data type.
The Ruby variable sigils are
$ and
@.
#!/usr/bin/ruby tree_name = "pine" $car_name = "Peugeot" @sea_name = "Black sea" @@species = "Cat" p local_variables p global_variables.include? :$car_name p self.instance_variables p Object.class_variables
We have four variables with different scopes. A scope is the range in which a variable can be referenced. We use special built-in methods to determine the scope of the variables.
tree_name = "pine"
A variable without a sigil is a local variable. A local variable is valid only locally: e.g., inside a method, block or a module.
$car_name = "Peugeot"
Global variables start with
$ character. They are valid everywhere.
The use of global variables should be limited in programs.
@sea_name = "Black sea"
A variable name starting with a
@ sigil is an instance variable.
This variable is valid inside an object.
@@species = "Cat"
Finally we have a class variable. This variable is valid for all instances of a specific class.
p local_variables
The
local_variables gives an array of all local variables
defined in a specific context. Our context is Ruby toplevel.
p global_variables.include? :$car_name
Similarly, the
global_variables produces an array of globals.
We do not print all globals to the terminal, because there are many of them.
Each Ruby script starts with a bunch of predefined variables. Instead of that,
we call the
include? method of the array to check
if our global is defined in the array. Also note that we are referencing
variables with their symbols. (Symbols start with a colon character.)
p self.instance_variables
The
self pseudo variable points to the receiver of the
instance_variables method. The receiver in our case is the
main, the Ruby toplevel execution area.
p Object.class_variables
Finally we have an array of class variables. The
main is
an instance of the
Object class.
$ ./sigils.rb [:tree_name] true [:@sea_name] [:@@species]
Output of the example. We see symbolic names of the variables.
Local variables
Local variables are variables that are valid within a local area of a Ruby source code. This area is also referred to as local scope. Local variables exist within the definition of a Ruby module, method, class.
#!/usr/bin/ruby def method1 x = 5 p x end method1 p x
We have a method called
method1, which has one
variable. The variable is local. This means that
it is valid only within the method definition.
We can refer to the
x variable only between the
method name and the
end keyword.
def method1 x = 5 p x end
This is the definition of the
method1 method. Inside the
method, we create a local
x variable. We print the value
of the variable to the terminal.
method1
The method is called.
p x
We try to refer to a local variable outside the definition
of the method. This leads to a
NameError.
The Ruby interpreter cannot find such identifier.
$ ./locals.rb 5 ./locals.rb:11:in `<main>': undefined local variable or method `x' for main:Object (NameError)
Running the example gives the above output.
The following example is a slight modification of a previous example.
#!/usr/bin/ruby x = 5 def method1 x = 10 p x end method1 p x
We have two
x variables. One is defined inside the
method1 and the other one is defined outside. They are two distinct
local variables. They do not clash with each other.
x = 5
We have created a local
x variable, which holds value 5.
The variable is valid in the local scope of the main execution area. It is not
valid inside the
method1.
def method1 x = 10 p x end
Inside the definition of the
method1 a new local variable
x is defined. It has value 10. It exists in the body of
the
method1 method. After the
end keyword it ceases to exist.
$ ./locals2.rb 10 5
Output.
If a method takes parameters, a local variable is created for each of these parameters.
#!/usr/bin/ruby def rectangle_area a, b puts local_variables return a * b end puts rectangle_area 5, 6
We have a method definition, which takes two values. The method returns the area of a rectangle.
def rectangle_area a, b puts local_variables return a * b end
The rectangle_area method takes two parameters. They
are the sides of a rectangle, for which we calculate
the area. Two local variables are automatically created for identifiers a and b.
We call the
local_variables
method to see what local variables we have in the method.
puts rectangle_area 5, 6
Here we pass two values to the method
rectangle_area.
The values will be assigned to two local variables, created
inside the method.
$ ./parameters.rb a b 30
The output shows three things. The first two are the names of the local variables within the rectangle_area method. The third is the calculated area of the given rectangle.
A method may be defined inside another method. The inner methods have their own local variables.
#!/usr/bin/ruby def method1 def method2 def method3 m5, m6 = 3 puts "Level 3" puts local_variables end m3, m4 = 3 puts "Level 2" puts local_variables method3 end m1, m2 = 3 puts "Level 1" puts local_variables method2 end method1
In this Ruby script, we create three methods. The
method2
and
method3 are inner methods. The
method2 is
defined inside the
method1 and the
method3 is defined inside
method2. Each method's local variables are only
accessible in the method in which they were defined.
$ ./lms.rb Level 1 m1 m2 Level 2 m3 m4 Level 3 m5 m6
From the output we can see that method1 has two local variables,
m1 and
m2. The inner
method2 has
local variables
m3 and
m4. The
method3,
the innermost method, has local variables
m5 and
m6.
The last example of this section will present several demonstrations of a local scope.
module ModuleM m1, m2 = 4 puts "Inside module" puts local_variables end def method1 v, w = 3 puts "Inside method" puts local_variables end class Some x, y = 2 puts "Inside class" puts local_variables end method1 t1, t2 = 7 puts "Inside toplevel" puts local_variables
In the code example, we create local variables inside a module,
method, class and toplevel. The
local_variables
is a method of the
Kernel module that returns all
current local variables.
module ModuleM m1, m2 = 4 puts "Inside module" puts local_variables end
A module is a collection of methods and constants.
We create two local variables
m1 and
m2.
def method1 v, w = 3 puts "Inside method" puts local_variables end
Two local variables,
v and
w, are created
in
method1.
class Some x, y = 2 puts "Inside class" puts local_variables end
The
x and
y local variables are created inside the
definition of the
Some class.
t1, t2 = 7
Finally, two local variables that belong to the Ruby toplevel's local scope are created.
$ ./locals3.rb Inside module m1 m2 Inside class x y Inside method v w Inside toplevel t1 t2
The output shows local variables for each local scope.
Global variables
Global variables are valid everywhere in the script. They start
with a
$ sigil in Ruby.
The use of global variables is discouraged. Global variables easily lead to many programming errors. Global variables should be used only when there is a reason to do so. Instead of global variables, programmers are advised to use local variables whenever possible.
#!/usr/bin/ruby $gb = 6 module ModuleM puts "Inside module" puts $gb end def method1 puts "Inside method" puts $gb end class Some puts "Inside class" puts $gb end method1 puts "Inside toplevel" puts $gb puts global_variables.include? :$gb
In the example we have a global variable
$gb. We show
that the variable can be referenced in a module, method, class and
a toplevel. The global variable
$gb is valid in all these entities.
$gb = 6
A global variable
$gb is created; it has value 6.
module ModuleM puts "Inside module" puts $gb end
Inside a module's definition we print the global variable's value.
def method1 puts "Inside method" puts $gb end
Inside the definition of a method we print the value of the global variable.
class Some puts "Inside class" puts $gb end
Inside the definition of a class we print the value of the global variable.
puts $gb puts global_variables.include? :$gb
Finally, in the toplevel execution area we print the global
variable's value and whether the variable is in the array produced
by the
global_variables method.
$ ./globals.rb Inside module 6 Inside class 6 Inside method 6 Inside toplevel 6 true
The output of the example confirms that the global variable is accessible everywhere.
When a Ruby script starts, it has access to multiple predefined global variables. These globals are not considered harmful and help solve common programming jobs.
#!/usr/bin/ruby p $LOAD_PATH p $:
The script shows a
$LOAD_PATH global variable. The
variable lists directories which are searched by
load
and
require methods. The
$: is a short synonym
for the
$LOAD_PATH name.
More global variables will be presented in the Predefined variables section of this chapter.
Instance, class variables
In this section we will briefly cover instance and class variables. They will be described in Object-oriented programming chapter in more detail.
Instance variables are variables that belong to a particular object
instance. Each object has its own object variables. Instance variables start
with a
@ sigil. Class variables belong
to a specific class. All objects created from a particular class share class
variables. Class variables start with
@@ characters.
#!/usr/bin/ruby class Being @@is = true def initialize nm @name = nm end def to_s "This is #{@name}" end def does_exist? @@is end end b1 = Being.new "Being 1" b2 = Being.new "Being 2" b3 = Being.new "Being 3" p b1, b2, b3 p b1.does_exist? p b2.does_exist? p b3.does_exist?
We create a custom
Being class. The
Being class
has one class and one instance variable.
class Being @@is = true
The
@@is is an class variable. This variable is shared by all
instances of the
Being class. The logic of this example is that
Being is and NotBeing is not.
def initialize nm @name = nm end
The
initialize method is a constructor. The method
is called when the object is created. A
@name instance variable is
created. This variable is specific to a concrete object.
def to_s "This is #{@name}" end
The
to_s method is called, when the object is a parameter
of a printing method, like
p or
puts. In our
case, the method gives a short human readable description of the object.
def does_exist? @@is end
The
does_exist? method returns the class variable.
b1 = Being.new "Being 1" b2 = Being.new "Being 2" b3 = Being.new "Being 3"
Three objects from the
Being class are created. Each of the
objects has a different name. The name of the object will
be stored in the instance method, which is unique to each object
instance. This will be used in the
to_s method, which
give a short description of the object.
p b1, b2, b3
The
p method takes the created objects as three parameters.
It calls the
to_s method on each of these objects.
p b1.does_exist? p b2.does_exist? p b3.does_exist?
Finally, we call the
does_exist? method of each of the instances and
print their return values. The output of these three methods is the
same, because each method returns the class variable.
$ ./icvars.rb This is Being 1 This is Being 2 This is Being 3 true true true
Output of the example. The first three messages are unique. The strings are stored in the instance variables of the objects. The true value is the value of the class variable, which is called three times.
Environment & command-line variables
The
ENV constant gives access to environment variables.
It is a Ruby hash. Each environment variable is a key to the
ENV hash.
The
ARGV constant holds command-line argument values.
They are passed by the programmer when the script is launched.
The
ARGV is an array that stores the arguments as
strings. The
$* is an alias to the
ARGV.
Both
ENV and
ARGV are global constants.
#!/usr/bin/ruby ARGV.each do |a| puts "Argument: #{a}" end
In the script we loop through the
ARGV array and
print each of its values.
$ ./commandline.rb 1 2 3 Argument: 1 Argument: 2 Argument: 3
We have given three command-line arguments. They are printed to the console, each on a separate line.
The following example will deal with environment variables.
#!/usr/bin/ruby puts ENV['SHELL'] puts ENV['LANG'] puts ENV['TERM']
The script will print values of three environment variables to the terminal. The values depend on the OS settings of our operating system.
$ ./environment.rb /bin/bash en_US.utf8 xterm
A sample output.
Pseudo variables
Ruby has a few variables which are called pseudo variables. They are different from regular variables. We cannot assign values to pseudo variables.
The
self is the receiver of the current method.
The
nil is the sole instance of the
NilClass.
It represents the absense of a value. The
true is the
sole instance of the
TrueClass. It represents boolean true.
The
false is a sole instance of
FalseClass.
It represents boolean false.
The true and false are values of a boolean datatype. From another point of view, they are instances of specific classes. This is because everything in Ruby is an object. This looks like unnecessarily complicated. But it is the consequence of the aforementioned Ruby idiom.
#!/usr/bin/ruby p self p nil p true p false p self.class p nil.class p true.class p false.class
This is an example of pseudo variables. We print all four
pseudo variables with the
p method. Then we
find out the class name for all of them.
p self
In this context, the
self pseudo variable returns
the main execution context.
$ ./pseudo.rb main nil true false Object NilClass TrueClass FalseClass
Example output.
In the second example of this section, we will further look
at the
self.
#!/usr/bin/ruby class Some puts self end class Other puts self end puts self
As we have said, the
self references the
receiver of the current method. The above example shows
three examples of different receivers.
class Some puts self end
The receiver is the class called
Some.
class Other puts self end
Here is another receiver: a class named
Other.
puts self
And the third receiver is the Ruby toplevel.
$ ./pseudoself.rb Some Other main
Example output.
The last example of the section will present other three pseudo variables.
#!/usr/bin/ruby if true puts "This message is shown" end if false puts "This message is not shown" end p $name p $age
The above example shows
true,
false
and
nil pseudo variables at work.
if true puts "This message is shown" end
The
true is used in boolean expression.
The message is always printed.
if false puts "This message is not shown" end
This message is never printed. The condition is not met. In the boolean expression we always get a negative value.
p $name p $age
If global values are referenced and have not been
initialized, they contain the
nil pseudo variable.
It stands for the absence of a value.
$ ./pseudo2.rb This message is shown nil nil
Output of the pseudo2.rb Ruby script.
Predefined variables
Ruby has plenty of predefined global variables. This is a heritage of Perl language. Ruby was influenced strongly by Perl. They are accessible when the Ruby script starts. We have a few examples for the predefined Ruby variables.
#!/usr/bin/ruby print "Script name: ", $0, "\n" print "Command line arguments: ", $*, "\n" puts "Process number of this script: #{$$}"
Three predefined variables have been used:
$0,
$* and
$$. The
$0 stores the current script name.
The
$* variable stores command-line arguments. And the
$$
stores the PID (process id) of the script.
$ ./predefined.rb 1 2 3 Script name: ./predefined.rb Command line arguments: ["1", "2", "3"] Process number of this script: 3122
Sample output.
The
$? global variable stores the exit status of
the last executed child process.
#!/usr/bin/ruby system 'echo "Ruby"' puts $? %x[exit '1'] puts $?
We run two external child processes and check their
exit status with the
$? variable.
system 'echo "Ruby"' puts $?
With the use of the
system method we start a
child process. It is an echo bash command, which prints a message
to the terminal.
%x[exit '1'] puts $?
In the second case we execute the bash
exit command with status 1.
This time we use the
%x operator which executes a command between
two selected delimiters. We have chosen
[] characters.
$ ./predefined2.rb Ruby pid 3131 exit 0 pid 3133 exit 1
The first child process terminates with status 0, the second with exit status 1.
The
$; variable has the default separator of the
split method of the
String class.
#!/usr/bin/ruby str = "1,2,3,4,5,6,7" p str.split $; = "," p str.split
We use the
$; variable to control how the string is cut with the
split method. The method takes a parameter, which tells
where the string should be split. If the parameter is omitted, than
the value from the
$; is used.
$; = "," p str.split
We specify a delimiter for the
$; variable. The split method does not
take a parameter, so the value of
$; is used.
$ ./predefined3.rb ["1,2,3,4,5,6,7"] ["1", "2", "3", "4", "5", "6", "7"]
In the first case, the string was not split. In the second case, the string was split correctly, as we have intended.
In the final example, we show three global predefined variables that are used with regular expressions.
#!/usr/bin/ruby "Her name is Jane" =~ /name/ p $` p $& p $'
When we apply the
=~ operator on a string, Ruby sets some variables.
The
$& variable has a string that matched the last last regular
expression match. The
$` has a string preceding
$&
and the
$’ has a string following the
$&.
$ ./predefined4.rb "Her " "name" " is Jane"
Example output.
In this part of the Ruby tutorial, we looked more deeply at the Ruby variables. | http://zetcode.com/lang/rubytutorial/variables/ | CC-MAIN-2016-18 | refinedweb | 3,498 | 68.16 |
Prerequisites :
Http Service
Let’s consider a simple service to get data using get method of Http service.
Let’s start with writing a test case for this service.
Configuring Testing Module for Service:
First of all, we need an instance of our service i.e. AppService. We can create one using the get method of TestBed.
let service = TestBed.get(AppService);
But for doing that, we also need to add the service to the providers of this testing environment. We will do that by configuring the testing module, like we do while testing our components.
Let’s do that in the beforeEach block
Notice that we don’t have the compileComponents method. We need that only for components as it converts your html and css urls to inline code. Also, since we don’t need to call it, we don’t need to wrap it in async block.
The first test case I always add is to check if the module is configured properly and the instance of our class is defined or not.
You’ll get an error :
Error: No provider for Http!
Ofcourse, when we look at the AppService, we have an Http object as a dependency. We’ll have to provide that as well. And if you take a look at the Http class, it needs two parameters ConnectionBackend and RequestOptions as dependencies :
constructor(_backend: ConnectionBackend, _defaultOptions: RequestOptions)
So, we need them as well.
Angular makes our job easy by providing mock object for ConnectionBackend. Just import that with the BaseRequestOptions as the second parameter to Http Object :
import {MockBackend} from '@angular/http/testing';
import {Http, BaseRequestOptions} from '@angular/http';
Now we will use useFactory, to provide an instance of Http. If you’re not familiar with that, you can checkout Angular’s documentation on dependency injection here.
So, in the above code, we have configured that whenever an instance of Http will be required, it will look into these providers to figure out how to create that instance. And for that we have provided a method that returns an Http object using the two parameters we imported earlier.
Now, your test case should work, as we should get an instance of AppService.
Testing Http Service:
Now, for testing the getData method, we obviously need to mock the connection that Http creates and makes an http request. But as we have already provided mock object of ConnectionBackend while providing Http instance, the test case won’t create an actual connection.
Also we can configure the response for each http request. We will do that using the connection property of MockBackend.
Let’s create an instance of mockBackend first using TestBed get method :
mockBackend = TestBed.get(MockBackend);
This is our final test case :
In the above test case, for every http request getData method makes, it will get the response that we have provided.
We can also cover the error scenario using the mockError method like this :
You can find the code for this blog here
1 thought on “Testing HTTP services in Angular3 min read”
Reblogged this on Coding, Unix & Other Hackeresque Things. | https://blog.knoldus.com/testing-http-services-in-angular/ | CC-MAIN-2021-04 | refinedweb | 517 | 61.97 |
The Tkinter 3000 RightArrow Widget
May 9, 2001 | Fredrik Lundh
This widget is an enhanced version of the SimpleRightArrow demo widget. This version provides three custom options, and it also precalculates graphics resources and coordinates.
from WCK import Widget, FOREGROUND class RightArrow(Widget): # widget implementation ui_option_foreground = FOREGROUND ui_option_width = 200 ui_option_height = 200 def ui_handle_config(self): # precalculate brush resource self.brush = self.ui_brush(self.ui_option_foreground) return int(self.ui_option_width), int(self.ui_option_height) def ui_handle_resize(self, width, height): # precalculate polygon self.arrow = (0, 0, width, height/2, 0, height) def ui_handle_repair(self, draw, x0, y0, x1, y1): draw.polygon(self.arrow, self.brush)
The ui_option_foreground class attribute provides two things: it tells the WCK that this widget supports an option called foreground, and it also provides a default value for that option (in this case, the default value is taken from the WCK.FOREGROUND variable, which contains a suitable default for the current platform). The ui_option_width and ui_option_height does the same for the width and height options.
The ui_handle_config() method is called when the widget is created, and whenever any of the options are changed. It creates a new brush based on the foreground option, and returns the requested width and height, in pixels. Note that users may use strings also for the size options, so this method uses int() to be on the safe side.
The ui_handle_resize() method is called when the widget is created, and whenever it’s resized (either by a geometry manager, or if ui_handle_config requests a new size). It is used to calculate the arrow outline.
The ui_handle_repair() method, finally, is called when the widget needs to be updated. It draws a polygon using the brush and coordinates set by the other two methods. | http://www.effbot.org/zone/tkinter3000-demo-rightarrow.htm | CC-MAIN-2015-06 | refinedweb | 286 | 54.63 |
Python is a super-popular, open-source, cross-platform programming language. It's commonly used for web applications, data science, and machine learning, and it's well-known in the maker community (especially for Raspberry Pi projects). If you're new to Python or just have a few pressing questions, this FAQ is for you.
Python is a cross-platform, open-source programming language. Its name comes from creator Guido van Rossum who felt inspired while reading scripts from the British comedy series Monty Python's Flying Circus.
Python can be used for a wide variety of both small and large-scale applications. You can use Python to program something simple like a clock display on a Raspberry Pi or something more complicated like a web app. Python can even be useful for calculating statistics or machine learning.
Python can be installed on Windows, Linux, and Mac systems. Python scripts can be written in any basic editor or text application. You can run Python-based applications or develop your own.
Python is available for download on the official Python website. There are different releases available on the downloads page. You can also download Python using a terminal application. The install command varies depending on your OS, terminal application, and edition you want to install.
If you downloaded Python from the Python website, you can install Python by running the installer file. You can also install Python via command line using a terminal application.
If you're using a Mac, check out our guide on how to install Python 3 on macOS.
You can nail the basics of Python in a couple of months. It helps to have a project in mind to help motivate you through the process. If you're feeling stuck, you can always check out our Python guides.
The method for checking your Python version varies between operating systems.
macOS
MacOS users can verify their Python version with the terminal application using the following command.
python --version
Windows
Windows users can check their Python version through Powershell using this command.
python --version
Linux
If you're using Linux, you can use this command in a Terminal window.
python --version
A note on other Python installations
The above commands will check your system Python version. If you have installed another version of Python—Python 3, for instance—you would check the version like this:
python3 --version
To code in Python, you'll need a text editor—preferably one designed for coding in Python. Python scripts can be saved as
.py files. Run the
.py file to run the script.
Python packages can be installed manually. If you're not sure what to run, look for a setup file.
You can also use a terminal or PIP to install packages. Check out our guide on How to install Python packages with PIP.
Functions are defined using
def. See the example below. This code creates a function called
function1 that prints a string.
def function1(): print("function1 has run.")
To call a function in Python, use the name of the function along with a set of parentheses. In this example, a function is defined called
function1 and called with
function1().
def function1(): print("function1 has run.") function1()
# sign. For example:
# This line is a comment. def function1(): print("function1 has run.") function1()
You can reverse a string in Python using one of multiple methods. This guide covers how to reverse a string in Python 3 using the extended slice operator and reverse function. | https://howchoo.com/python/python-faq | CC-MAIN-2020-40 | refinedweb | 583 | 67.04 |
While working with files, you should know which Python directory you are using, where your files are storing so on. If you know them, you can easily change the working directories or even create subfolders to organize your files.
In this programming language, we have an os module, which contains all the necessary functions to work with file directories. So, to work with the methods, you have to import this os module.
Python Directory Examples
The following list of examples helps you to understand the available functions, which helps you to work with Directory. They are getcwd, chdir, listdir, mkdir, rmdir, and rename function.
How to Get a Current Directory?
The getcwd method returns the current working directory. This getcwd function example shows you the same.
import os print(os.getcwd())
/Users/suresh/Documents/Simple Python
The getcwd method helps you to change the current folder to a new location.
import os print(os.getcwd()) os.chdir('/Users/suresh/Documents') print(os.getcwd())
Output of changing current dir
/Users/suresh/Documents/Simple Python /Users/suresh/Documents
Directory and Files list
The listdir method returns all the files and the subfolders available inside that folder.
import os print(os.getcwd()) print(os.listdir())
Create a New Directory in Python
The mkdir method creates a new folder. If you want this dir inside the current working folder, then simply specify the folder name; otherwise, specify the full path.
import os print(os.getcwd()) os.mkdir('NewPython') print(os.listdir())
Let me provide the full path so that I can create a folder in a different location. Here, we first created a folder. Next, we changed the current working folder using the chdir method. Next, list the documents and folders inside that it using listdir.
import os print(os.getcwd()) os.mkdir('/Users/suresh/Documents/NewPython') os.chdir('/Users/suresh/Documents') print(os.listdir())
Rename a Directory
The rename function present in the os module helps us to rename existing files or even renaming folders. Here, we use this rename file function to rename PythonSampleCopy to the Sample1 text.
import os print(os.getcwd()) print(os.listdir()) os.rename("PythonSampleCopy.txt", "Sample1.txt") print(os.listdir())
The rename function that we mentioned above also renames the directory. Let us use this rename folder function to rename FirstFolder to SecondFolder.
import os print(os.getcwd()) print(os.listdir()) os.rename("FirstFolder", "SecondFolder") print(os.listdir())
Delete a File
A remove function is to remove files from a folder. This example uses a sample inside the remove function to delete the CopyFile.txt.
First, we are listing out the files in the current working folder. Next, we removed that particular one and then printed the files.
import os print(os.getcwd()) print(os.listdir()) os.remove("CopyFiles.txt") print(os.listdir())
The rmdir function is to delete a Python directory. Here, we used the rmdir function to delete the existing SecondFolder.
import os print(os.getcwd()) print(os.listdir()) os.rmdir("SecondFolder") print(os.listdir())
| https://www.tutorialgateway.org/python-directory/ | CC-MAIN-2022-40 | refinedweb | 500 | 51.44 |
Implement a chat server nr) mainLoop sock chan
And finally,
runConn will duplicate the channel and read from it.
import Control.Monad import Control.Monad.Fix (fix) [...] runConn :: (Socket, SockAddr) -> Chan Msg -> -> IO () runConn (sock, _) chan = do let broadcast msg = writeChan chan msg hdl <- socketToHandle sock ReadWriteMode hSetBuffering hdl NoBuffering chan' <- dupChan chan -- fork off thread for reading from the duplicated channel forkIO $ fix $ \loop -> do line <- readChan chan' hPutStrLn hdl line loop -- read lines from socket and echo them back to the user fix $ \loop -> do line <- liftM init (hGetLine hdl) broadcast line loop
Note that
runConn now actually forks another worker thread for sending messages to the connected user.
Cleanups and final code
There are two major problems left in the code. First, the code has a memory leak, because the original channel is never read by anyone. This can be fixed by adding another thread just for that purpose.
Secondly, closing connections is not handled gracefully at all. This requires exception handling.
The code below fixes the first issue and mostly fixes the second one, and adds a few cosmetic improvements:
- messages are not echoed back to the user they came from.
- every connection is associated with a name.
-- with apologies for the lack of comments :) import Network.Socket import System.IO import Control.Exception import Control.Concurrent import Control.Concurrent.Chan import Control.Monad import Control.Monad.Fix (fix) type Msg = (Int, String) main :: IO () main = do chan <- newChan sock <- socket AF_INET Stream 0 setSocketOption sock ReuseAddr 1 bindSocket sock (SockAddrInet 4242 iNADDR_ANY) listen sock 2 forkIO $ fix $ \loop -> do (_, msg) <- readChan chan loop mainLoop sock chan 0 mainLoop :: Socket -> Chan Msg -> Int -> IO () mainLoop sock chan nr = do conn <- accept sock forkIO (runConn conn chan nr) mainLoop sock chan $! nr+1 runConn :: (Socket, SockAddr) -> Chan Msg -> Int -> IO () runConn (sock, _) chan nr = do let broadcast msg = writeChan chan (nr, msg) hdl <- socketToHandle sock ReadWriteMode hSetBuffering hdl NoBuffering hPutStrLn hdl "Hi, what's your name?" name <- liftM init (hGetLine hdl) broadcast ("--> " ++ name ++ " entered.") hPutStrLn hdl ("Welcome, " ++ name ++ "!") chan' <- dupChan chan reader <- forkIO $ fix $ \loop -> do (nr', line) <- readChan chan' when (nr /= nr') $ hPutStrLn hdl line loop handle (\_ -> return ()) $ fix $ \loop -> do line <- liftM init (hGetLine hdl) case line of "quit" -> hPutStrLn hdl "Bye!" _ -> do broadcast (name ++ ": " ++ line) loop killThread reader broadcast ("<-- " ++ name ++ " left.") hClose hdl
Have fun chatting! | https://wiki.haskell.org/index.php?title=Implement_a_chat_server&oldid=13113 | CC-MAIN-2019-47 | refinedweb | 397 | 63.7 |
03 December 2013 15:51 [Source: ICIS news]
LONNDON (ICIS)--SABIC’s Innovative Plastics business unit on Tuesday announced two investments to improve the competitiveness of its largest US manufacturing site at ?xml:namespace>
The first investment is for the construction of a cogeneration (cogen) plant that will use natural gas to create most of the steam for the site. Currently, coal boilers power 40% of the site’s steam.
The cogen plant is expected to reduce the site's greenhouse gas intensity while improving energy efficiency, SABIC said.
In the second investment at
SABIC said that the investments would result in up to 200 temporary construction jobs over two and a half years. It did not disclose how much money it expects to invest.
The company has about 1,200 employees | http://www.icis.com/Articles/2013/12/03/9732156/sabic-invests-to-upgrade-mount-vernon-indiana-site.html | CC-MAIN-2014-52 | refinedweb | 132 | 53.31 |
In for loop, we already know how many times code inside loop will be executed based on conditions, but in "while" loop, code inside the loop will be excuted until a particular condition is true.
So While loop can be used when number of iterations of a code is unknown.
Syntax for while loop
while(condition) { //code to be executed }
Example:
using System; public class WhileLoopProgram { public static void Main() { int i; Console.WriteLine("How many times you want to print i?"); i = Convert.ToInt32(Console.ReadLine()); while(i > 0) { Console.WriteLine("Value of i="+i); i--; } } }
Output:
How many times you want to print i? 10 Value of i=10 Value of i=9 Value of i=8 Value of i=7 Value of i=6 Value of i=5 Value of i=4 Value of i=3 Value of i=2 Value of i=1
In the above code, we are getting value of "i" from user, by using
Console.ReadLine() which is used to read value entered by user. But as this value is in string we are converting value to "
int" using
Convert.ToInt32() method.
Using While loop we are printing values of i until the value of "i" is not equal to 0 or you can say it prints until it's value is greater than 0.
Another simple example of while loop
public static void Main() { int num= 1; while (num < 10) { Console.WriteLine(num++); } }
Output:
1 2 3 4 5 6 7 8 9
In while loop we can make loop for infinite by placing true inside the condition
while (true) // Executes forever { Console.WriteLine("Never Stop!"); }
Next example, will never execute
while (false) // Never executes { Console.WriteLine("Never execute"); }
You can place while loop inside another loop, just like for loop, here is the example for it
using System; public class NestedWhileLoopProgram { public static void Main() { int i=1; while(i<=3) { int j = 1; while (j <= 3) { Console.WriteLine(i+" "+j); j++; } Console.WriteLine("End of iteratoin number "+i +" of while loop"); i++; } } }
Output:
1 1 1 2 1 3 End of iteratoin number 1 of while loop 2 1 2 2 2 3 End of iteratoin number 2 of while loop 3 1 3 2 3 3 End of iteratoin number 3 of while loop | https://qawithexperts.com/tutorial/c-sharp/15/c-sharp-while-loop | CC-MAIN-2021-39 | refinedweb | 385 | 57.81 |
Cloud Firestore is a blazing-fast, serverless NoSQL database, perfect for
powering web and mobile apps of any size. Grab the complete guide to learning Firestore, created to show you how to use Firestore as the engine for your own JavaScript projects from front to back.
Table of Contents
Getting Started with Firestore
- What is Firestore? Why Should You Use It?
- Setting Up Firestore in a JavaScript Project
- Firestore Documents and Collections
- Managing our Database with the Firebase Console
Fetching Data with Firestore
- Getting Data from a Collection with .get()
- Subscribing to a Collection with .onSnapshot()
- Difference between .get() and .onSnapshot()
- Unsubscribing from a collection
- Getting individual documents
Changing Data with Firestore
- Adding document to a collection with .add()
- Adding a document to a collection with .set()
- Updating existing data
- Deleting data
Essential Patterns
- Working with subcollections
- Useful methods for Firestore fields
- Querying with .where()
- Ordering and limiting data
Note: you can download a PDF version of this tutorial so you can read it offline!
What is Firestore? Why Should You Use It?
Firestore is a very flexible, easy to use database for mobile, web and server development. If you're familiar with Firebase's realtime database, Firestore has many similarities, but with a different (arguably more declarative) API.
Here are some of the features that Firestore brings to the table:
⚡️Easily get data in realtime
Like the Firebase realtime database, Firestore provides useful methods such as
.onSnapshot() which make it a breeze to listen for updates to your data in
real time. It makes Firestore an ideal choice for projects that place a
premium on displaying and using the most recent data (chat applications, for
instance).
🥞 Flexibility as a NoSQL Database
Firestore is a very flexible option for a backend because it is a NoSQL
database. NoSQL means that the data isn't stored in tables and columns as a
standard SQL database would be. It is structured like a key-value store, as if
it was one big JavaScript object. In other words, there's no schema or need to
describe what data our database will store. As long as we provide valid keys
and values, Firestore will store it.
↕️ Effortlessly scalable
One great benefit of choosing Firestore for your database is the very powerful
infrastructure that it builds upon that enables you to scale your application
very easily. Both vertically and horizontally. No matter whether you have
hundreds or millions of users. Google's servers will be able to handle
whatever load you place upon it.
In short, Firestore is a great option for applications both small and large.
For small applications it's powerful because we can do a lot without much
setup and create projects very quickly with them. Firestore is well-suited for
large projects due to it's scalability.
Setting Up Firestore in a JavaScript Project
We're going to be using the Firestore SDK for JavaScript. Throughout this
cheatsheet, we'll cover how to use Firestore within the context of a
JavaScript project. In spite of this, the concepts we'll cover here are easily
transferable to any of the available Firestore client libraries.
To get started with Firestore, we'll head to the Firebase console. You can
visit that by going to firebase.google.com. You'll
need to have a Google account to sign in.
Once we're signed in, we'll create a new project and give it a name.
Once our project is created, we'll select it. After that, on our project's
dashboard, we'll select the code button.
This will give us the code we need to integrate Firestore with our JavaScript project.
Usually if you're setting this up in any sort of JavaScript application,
you'll want to put this in a dedicated file called firebase.js. If you're
using any JavaScript library that has a package.json file, you'll want to
install the Firebase dependency with npm or yarn.
// with npm npm i firebase // with yarn yarn add firebase
Firestore can be used either on the client or server. If you are using
Firestore with Node, you'll need to use the CommonJS syntax with require.
Otherwise, if you're using JavaScript in the client, you'll import firebase
using ES Modules.
// with Commonjs syntax (if using Node) const firebase = require("firebase/app"); require("firebase/firestore"); // with ES Modules (if using client-side JS, like React) import firebase from 'firebase/app'; import 'firebase/firestore'; var firebaseConfig = { apiKey: "AIzaSyDpLmM79mUqbMDBexFtOQOkSl0glxCW_ds", authDomain: "lfasdfkjkjlkjl.firebaseapp.com", databaseURL: "", projectId: "lfasdlkjkjlkjl", storageBucket: "lfasdlkjkjlkjl.appspot.com", messagingSenderId: "616270824980", appId: "1:616270824990:web:40c8b177c6b9729cb5110f", }; // Initialize Firebase firebase.initializeApp(firebaseConfig);
Firestore Collections and Documents
There are two key terms that are essential in understanding how to work with
Firestore: documents and collections.
Documents are individual pieces of data in our database. You can think of
documents to be much like simple JavaScript objects. They consist of key-value
pairs, which we refer to as fields. The values of these fields can be
strings, numbers, Booleans, objects, arrays, and even binary data.
document -> { key: value }
Sets of these documents of these documents are known as collections.
Collections are very much like arrays of objects. Within a collection, each
document is linked to a given identifier (id).
collection -> [{ id: doc }, { id: doc }]
Managing our database with the Firestore Console
Before we can actually start working with our database we need to create it.
Within our Firebase console, go to the 'Database' tab and create your
Firestore database.
Once you've done that, we will start in test mode and enable all reads and
writes to our database. In other words, we will have open access to get and
change data in our database. If we were to add Firebase authentication, we
could restrict access only to authenticated users.
After that, we'll be taken to our database itself, where we can start creating
collections and documents. The root of our database will be a series of
collections, so let's make our first collection.
We can select 'Start collection' and give it an id. Every collection is going
to have an id or a name. For our project, we're going to keep track of our
users' favorite books. We'll give our first collection the id 'books'.
Next, we'll add our first document with our newly-created 'books' collection.
Each document is going to have an id as well, linking it to the collection in
which it exists.
In most cases we're going to use an option to give it an automatically
generated ID. So we can hit the button 'auto id' to do so, after which we need
to provide a field, give it a type, as well as a value.
For our first book, we'll make a 'title' field of type 'string', with the
value 'The Great Gatsby', and hit save.
After that, we should see our first item in our database.
Getting data from a collection with .get()
To get access Firestore use all of the methods it provides, we use
firebase.firestore(). This method need to be executed every time we want to
interact with our Firestore database.
I would recommend creating a dedicated variable to store a single reference to
Firestore. Doing so helps to cut down on the amount of code you write across
your app.
const db = firebase.firestore();
In this cheatsheet, however, I'm going to stick to using the firestore
method each time to be as clear as possible.
To reference a collection, we use the
.collection() method and provide a
collection's id as an argument. To get a reference to the books collection we
created, just pass in the string 'books'.
const booksRef = firebase.firestore().collection('books');
To get all of the document data from a collection, we can chain on the
.get() method.
.get() returns a promise, which means we can resolve it either using a
.then() callback or we can use the async-await syntax if we're executing our
code within an async function.
Once our promises is resolved in one way or another, we get back what's known
as a snapshot.
For a collection query that snapshot is going to consist of a number of
individual documents. We can access them by saying
snapshot.docs.
From each document, we can get the id as a separate property, and the rest of
the data using the
.data() method.
Here's what our entire query looks like:
const booksRef = firebase .firestore() .collection("books"); booksRef .get() .then((snapshot) => { const data = snapshot.docs.map((doc) => ({ id: doc.id, ...doc.data(), })); console.log("All data in 'books' collection", data); // [ { id: 'glMeZvPpTN1Ah31sKcnj', title: 'The Great Gatsby' } ] });
Subscribing to a collection with .onSnapshot()
The
.get() method simply returns all the data within our collection.
To leverage some of Firestore's realtime capabilities we can subscribe to a
collection, which gives us the current value of the documents in that
collection, whenever they are updated.
Instead of using the
.get() method, which is for querying a single time, we
use the
.onSnapshot() method.
firebase .firestore() .collection("books") .onSnapshot((snapshot) => { const data = snapshot.docs.map((doc) => ({ id: doc.id, ...doc.data(), })); console.log("All data in 'books' collection", data); });
In the code above, we're using what's known as method chaining instead of
creating a separate variable to reference the collection.
What's powerful about using firestore is that we can chain a bunch of methods
one after another, making for more declarative, readable code.
Within onSnapshot's callback, we get direct access to the snapshot of our
collection, both now and whenever it's updated in the future. Try manually
updating our one document and you'll see that
.onSnapshot() is listening for
any changes in this collection.
Difference between .get() and .onSnapshot()
The difference between the get and the snapshot methods is that get returns a
promise, which needs to be resolved, and only then we get the snapshot data.
.onSnapshot, however, utilizes synchronous callback function, which gives us
direct access to the snapshot.
This is important to keep in mind when it comes to these different methods--we
have to know which of them return a promise and which are synchronous.
Unsubscribing from a collection with unsubscribe()
Note additionally that
.onSnapshot() returns a function which we can use to
unsubscribe and stop listening on a given collection.
This is important in cases where the user, for example, goes away from a given
page where we're displaying a collection's data. Here's an example, using the
library React were we are calling unsubscribe within the useEffect hook.
When we do so this is going to make sure that when our component is unmounted
(no longer displayed within the context of our app) that we're no longer
listening on the collection data that we're using in this component.
function App() { const [books, setBooks] = React.useState([]); React.useEffect(() => { const unsubscribe = firebase .firestore() .collection("books") .onSnapshot((snapshot) => { const data = snapshot.docs.map((doc) => ({ id: doc.id, ...doc.data(), })); setBooks(data); }); return () => unsubscribe(); }, []); return books.map(book => <BookList key={book.id} book={book} />) }
Getting Individual Documents with .doc()
When it comes to getting a document within a collection., the process is just
the same as getting an entire collection: we need to first create a reference
to that document, and then use the get method to grab it.
After that, however, we use the
.doc() method chained on to the collection
method. In order to create a reference, we need to grab this id from the
database if it was auto generated. After that, we can chain on
.get() and
resolve the promise.
const bookRef = firebase .firestore() .collection("books") .doc("glMeZvPpTN1Ah31sKcnj"); bookRef.get().then((doc) => { if (!doc.exists) return; console.log("Document data:", doc.data()); // Document data: { title: 'The Great Gatsby' } });
Notice the conditional
if (!doc.exists) return; in the code above.
Once we get the document back, it's essential to check to see whether it
exists.
If we don't, there'll be an error in getting our document data. The way to
check and see if our document exists is by saying, if
doc.exists, which
returns a true or false value.
If this expression returns false, we want to return from the function or maybe
throw an error. If
doc.exists is true, we can get the data from
doc.data.
Adding document to a collection with .add()
Next, let's move on to changing data. The easiest way to add a new document to
a collection is with the
.add() method.
All you need to do is select a collection reference (with
.collection()) and
chain on
.add().
Going back to our definition of documents as being like JavaScript objects, we
need to pass an object to the
.add() method and specify all the fields we
want to be on the document.
Let's say we want to add another book, 'Of Mice and Men':
firebase .firestore() .collection("books") .add({ title: "Of Mice and Men", }) .then((ref) => { console.log("Added doc with ID: ", ref.id); // Added doc with ID: ZzhIgLqELaoE3eSsOazu });
The
.add method returns a promise and from this resolved promise, we get
back a reference to the created document, which gives us information such as
the created id.
The
.add() method auto generates an id for us. Note that we can't use this
ref directly to get data. We can however pass the ref to the doc method to
create another query.
Adding a document to a collection with .set()
Another way to add a document to a collection is with the
.set() method.
Where set differs from add lies in the need to specify our own id upon adding
the data.
This requires chaining on the
.doc() method with the id that you want to
use. Also, note how when the promise is resolved from
.set(), we don't get a
reference to the created document:
firebase .firestore() .collection("books") .doc("another book") .set({ title: "War and Peace", }) .then(() => { console.log("Document created"); });
Additionally, when we use
.set() with an existing document, it will, by
default, overwrite that document.
If we want to merge, an old document with a new document instead of
overwriting it, we need to pass an additional argument to
.set() and provide
the property
merge set to true.
// use .set() to merge data with existing document, not overwrite const bookRef = firebase .firestore() .collection("books") .doc("another book"); bookRef .set({ author: "Lev Nikolaevich Tolstoy" }, { merge: true }) .then(() => { console.log("Document merged"); bookRef .get() .then(doc => { console.log("Merged document: ", doc.data()); // Merged document: { title: 'War and Peace', author: 'Lev Nikolaevich Tolstoy' } }); });
Updating existing data with .update()
When it comes to updating data we use the update method, like
.add() and
.set() it returns a promise.
What's helpful about using
.update() is that, unlike
.set(), it won't
overwrite the entire document. Also like
.set(), we need to reference an
individual document.
When you use
.update(), it's important to use some error handling, such as
the
.catch() callback in the event that the document doesn't exist.
const bookRef = firebase.firestore().collection("books").doc("another book"); bookRef .update({ year: 1869, }) .then(() => { console.log("Document updated"); // Document updated }) .catch((error) => { console.error("Error updating doc", error); });
Deleting data with .delete()
We can delete a given document collection by referencing it by it's id and
executing the
.delete() method, simple as that. It also returns a promise.
Here is a basic example of deleting a book with the id "another book":
firebase .firestore() .collection("books") .doc("another book") .delete() .then(() => console.log("Document deleted")) // Document deleted .catch((error) => console.error("Error deleting document", error));
Note that the official Firestore documentation does not recommend to delete
entire collections, only individual documents.
Working with Subcollections
Let's say that we made a misstep in creating our application, and instead of
just adding books we also want to connect them to the users that made them. T
The way that we want to restructure the data is by making a collection called
'users' in the root of our database, and have 'books' be a subcollection of
'users'. This will allow users to have their own collections of books. How do
we set that up?
References to the subcollection 'books' should look something like this:
const userBooksRef = firebase .firestore() .collection('users') .doc('user-id') .collection('books');
Note additionally that we can write this all within a single
.collection()
The above code is equivalent to the follow, where the collection reference
must have an odd number of segments. If not, Firestore will throw an error.
const userBooksRef = firebase .firestore() .collection('users/user-id/books');
To create the subcollection itself, with one document (another Steinbeck
novel, 'East of Eden') run the following.
firebase.firestore().collection("users/user-1/books").add({ title: "East of Eden", });
Then, getting that newly created subcollection would look like the following
based off of the user's ID.
firebase .firestore() .collection("users/user-1/books") .get() .then((snapshot) => { const data = snapshot.docs.map((doc) => ({ id: doc.id, ...doc.data(), })); console.log(data); // [ { id: 'UO07aqpw13xvlMAfAvTF', title: 'East of Eden' } ] });
Useful methods for Firestore fields
There are some useful tools that we can grab from Firestore that enables us to
work with our field values a little bit easier.
For example, we can generate a timestamp for whenever a given document is
created or updated with the following helper from the
FieldValue property.
We can of course create our own date values using JavaScript, but using a
server timestamp lets us know exactly when data is changed or created from
Firestore itself.
firebase .firestore() .collection("users") .doc("user-2") .set({ created: firebase.firestore.FieldValue.serverTimestamp(), }) .then(() => { console.log("Added user"); // Added user });
Additionally, say we have a field on a document which keeps track of a certain
number, say the number of books a user has created. Whenever a user creates a
new book we want to increment that by one.
An easy way to do this, instead of having to first make a
.get() request, is
to use another field value helper called
.increment():
const userRef = firebase.firestore().collection("users").doc("user-2"); userRef .set({ count: firebase.firestore.FieldValue.increment(1), }) .then(() => { console.log("Updated user"); userRef.get().then((doc) => { console.log("Updated user data: ", doc.data()); }); });
Querying with .where()
What if we want to get data from our collections based on certain conditions?
For example, say we want to get all of the users that have submitted one or
more books?
We can write such a query with the help of the
.where() method. First we
reference a collection and then chain on
.where().
The where method takes three arguments--first, the field that we're searching
on an operation, an operator, and then the value on which we want to filter
our collection.
We can use any of the following operators and the fields we use can be
primitive values as well as arrays.
<,
<=,
==,
>,
>=,
array-contains,
in, or
array-contains-any
To fetch all the users who have submitted more than one book, we can use the
following query.
After
.where() we need to chain on
.get(). Upon resolving our promise we
get back what's known as a querySnapshot.
Just like getting a collection, we can iterate over the querySnapshot with
.map() to get each documents id and data (fields):
firebase .firestore() .collection("users") .where("count", ">=", 1) .get() .then((querySnapshot) => { const data = querySnapshot.docs.map((doc) => ({ id: doc.id, ...doc.data(), })); console.log("Users with > 1 book: ", data); // Users with > 1 book: [ { id: 'user-1', count: 1 } ] });
Note that you can chain on multiple
.where()methods to create compound
queries.
Limiting and ordering queries
Another method for effectively querying our collections is to limit them.
Let's say we want to limit a given query to a certain amount of documents.
If we only want to return a few items from our query, we just need to add on
the
.limit() method, after a given reference.
If we wanted to do that through our query for fetching users that have
submitted at least one book, it would look like the following.
const usersRef = firebase .firestore() .collection("users") .where("count", ">=", 1); usersRef.limit(3)
Another powerful feature is to order our queried data according to document
fields using
.orderBy().
If we want to order our created users by when they were first made, we can use
the
orderBy method with the 'created' field as the first argument. For the
second argument, we specify whether it should be in ascending or descending
order.
To get all of the users ordered by when they were created from newest to
oldest, we can execute the following query:
const usersRef = firebase .firestore() .collection("users") .where("count", ">=", 1); usersRef.orderBy("created", "desc").limit(3);
We can chain
.orderBy() with
.limit(). For this to work properly,
.limit() should be called last and not before
.orderBy().
Want your own copy? 📝
If you would like to have this guide for future reference, download a
cheatsheet of this entire tutorial here.
Click to grab the cheatsheet
Discussion
This is good but in
Unsubscribing from a collection with unsubscribe(), you forgot to return the
unsubscribefunction that should have done the actual unsubscription. It should be:
I mentioned it, but didn't include it. Thanks, fixed.
You are welcome 😉😉😉
Awesome cheatsheet, thanks you
Thanks a lot for the cheatsheet ! | https://practicaldev-herokuapp-com.global.ssl.fastly.net/reedbarger/the-firestore-tutorial-for-2020-learn-by-example-341j | CC-MAIN-2021-04 | refinedweb | 3,570 | 58.28 |
> The. > Argh! In commdlg.h (not ours) there is this code: #ifdef UNICODE #define FindText FindTextW #else #define FindText FindTextA #endif // !UNICODE That is completely rude. That means no one can define a method, class, or variable named 'FindText'! Anyway, this first problem is fixed now (with #undef FindText) I've noticed another problem. the speed-buttons to turn on and off certain OptionFilters work ok, but the complete list in the menus doesn't work. Odd. Anyone have time to figure this one out, it would be appreciated. Also added a README.txt to explain how to checkout and compile. -Troy. >: > > > > _______________________________________________ > sword-devel mailing list: sword-devel at crosswire.org > > Instructions to unsubscribe/change your settings at above page > | http://www.crosswire.org/pipermail/sword-devel/2007-March/025151.html | CC-MAIN-2018-09 | refinedweb | 121 | 68.57 |
# PennyBoki @ puts 'Enter a number' STDOUT.flush string1 = gets.chomp puts 'The factorial of '+string1+' is' y = string1.to_i def factorial(y) if y==0 return 1 else return (y*factorial(y-1)) end end x = factorial(y) puts x.to_s
Factorial By RecursionPage 1 of 1
2 Replies - 1585 Views - Last Post: 29 December 2011 - 04:50 PM
#1
Factorial By Recursion
Posted 21 July 2007 - 01:07 PM
Description: Just copy the code and run it in a Ruby InterpreterFinds the factorial of a number by using a recursive function
Replies To: Factorial By Recursion
#2
Re: Factorial By Recursion
Posted 15 April 2009 - 09:42 AM
thx
#3
Re: Factorial By Recursion
Posted 29 December 2011 - 04:50 PM
Know that factorial in a non-recursive manner is much faster: (1..10000).inject(1){|fact, x| fact *= x}
Page 1 of 1 | https://www.dreamincode.net/forums/topic/365907-Factorial-By-Recursion/ | CC-MAIN-2019-30 | refinedweb | 145 | 50.16 |
In Java, a method is a block of statements that has a name and can be executed by calling (also called invoking) it from some other place in your program. You may not realize it, but you're already very experienced with using methods. For example, to print text to the console, you use the println or print method. To get an integer from the user, you use the nextInt method. And to compare string values, you use either the equals method or the equalsIgnoreCase method. And the granddaddy of all methods, main, is the method that contains the statements that are executed when you run your program.
All the methods you've used so far (with the exception of main) have been methods that are defined by the Java API and that belong to a particular Java class. For example, the nextInt method belongs to the Scanner class, and the equalsIgnoreCase method belongs to the String class.
In contrast, the main method belongs to the class defined by your application. In this chapter, you find out how to create additional methods that are a part of your application's class. You can then call these methods from your main method. As you'll see, this method turns out to be very useful for all but the shortest Java programs.
The use of methods can dramatically improve the quality of your programming life. For example, suppose the problem your program is supposed to solve is complicated and you need at least 1,000 Java statements to get ‘er done. You could put all those 1,000 statements in the main method, but it would go on for pages and pages. It's better to break your program up into a few well-defined sections of code and place each of those sections in a separate method. Then your main method can simply call the other methods in the right sequence.
Or suppose your program needs to perform some calculation, such as how long to let the main rockets burn to make a mid-course correction on a moon flight, and the program needs to perform this calculation in several different places. Without methods, you'd have to duplicate the statements that do this calculation. That's not only error-prone, but makes your programs more difficult to test and debug. But if you put the calculation in a method, you can simply call the method whenever you need to perform the calculation. Thus methods help you cut down on repetitive code.
Another good use for methods is to simplify the structure of your code that uses long loops. For example, suppose you have a while loop that has 500 statements in its body. That makes it pretty hard to track down the closing brace that marks the end of the body. By the time you find it, you probably will have forgotten what the while loop does. You can simplify this while loop by placing the code from its body in a separate method. Then all the while loop has to do is call the new method.
Well, phooey. They're right, but so what? I get to the object-oriented uses for methods in Book III. There, you find out that methods have a far greater purpose than simply breaking a long main method into smaller pieces. But even so, some of the most object-oriented programs I know use methods just to avoid repetitive code or to slice a large method into a couple of smaller ones. So there.
All methods-including the main method-must begin with a method declaration. Here's the basic form for a method declaration, at least for the types of methods I talk about in this chapter:
public static return-type method-name (parameter-list) { statements... }
The following paragraphs describe method declarations piece by piece:
Okay, all that was a little abstract. Now for a concrete example, I offer a version of the Hello, World! program in which the message is displayed not by the main method, but by a method named sayHello that's called by the main method:
public class HelloWorldMethod { public static void main(String[] args) { sayHello(); } public static void sayHello() { System.out.println("Hello, World!"); } }
This program is admittedly trivial, but it illustrates the basics of creating and using methods in Java. Here the statement in the main method calls the sayHello method, which in turn displays a message on the console.
This version of the program works exactly like the previous version.
Okay, the last example was kind of dumb. No one in his (or her) right mind would create a method that has just one line of code, and then call it from another method that also has just one line of code. The Hello, World! program is too trivial to illustrate anything remotely realistic.
For example, a program in Book II, Chapter 5, plays a guessing game. Most of this program's main method is a large while loop that repeats the game as long as the user wants to keep playing. This loop has 41 statements in its body. That's not so bad, but what if the game were 100 times more complicated, so that the while loop needed 4,100 statements to play a single cycle of the game? Do you really want a while loop that has 4,100 statements in its body? I should think not.
Listing 7-1 shows how you can simplify this game a bit just by placing the body of the main while loop into a separate method. I called this method playARound, because its job is to play one round of the guessing game. Now, instead of actually playing a round of the game, the main method of this program delegates that task to the playARound method.
Listing 7-1: A Version of the Guessing Game Program
import java.util.Scanner; public class GuessingGameMethod { static Scanner sc = new Scanner(System.in); static boolean keepPlaying = true; → 7 public static void main(String[] args) { System.out.println("Let's play a quessing game"); while (keepPlaying) → 12 { playARound(); → 14 } System.out.println(" Thank you for playing!"); } public static void playARound() → 19 { boolean validInput; int number, guess; String answer; // Pick a random number number = (int)(Math.random() * 10) + 1; System.out.println(" I'm thinking of a number " + "between 1 and 10."); // Get the guess System.out.print("What do you think it is? "); do { guess = sc.nextInt(); validInput = true; if ((guess < 1) || (guess > 10)) { System.out.print("I said, between 1 " + "and 10. Try again: "); validInput = false; } } while (!validInput); // Check the guess if (guess == number) System.out.println("You're right"); else System.out.println("You're wrong!" + " The number was " + number); // Play again? do { System.out.print(" Play again? (Y or N)"); answer = sc.next(); validInput = true; if (answer.equalsIgnoreCase("Y")) ; else if (answer.equalsIgnoreCase("N")) keepPlaying = false; else validInput = false; } while (!validInput); } }
Here are a few important details to notice about this method:
Methods that just do work without returning any data are useful only in limited situations. The real utility of methods comes when they can perform some mundane task such as a calculation, and then return the value of that calculation to the calling method so the calling method can do something with the value. You find out how to do that in the following sections.
To create a method that returns a value, you simply indicate the type of the value returned by the method on the method declaration in place of the void keyword. For example, here's a method declaration that creates a method that returns an int value:
public static int getRandomNumber()
Here the getRandomNumber method calculates a random number, and then returns the number to the caller.
Alternatively, the return type can be a reference type, including a class defined by the API such as String or a class you create yourself.
When you specify a return type other than void in a method declaration, the body of the method must include a return statement that specifies the value to be returned. The return statement has this form:
return expression;
The expression must evaluate to a value that's the same type as the type listed in the method declaration. In other words, if the method returns an int, the expression in the return statement must evaluate to an int.
For example, here's a program that uses a method that determines a random number between 1 and 10:
public class RandomNumber { public static void main(String[] args) { int number = getRandomNumber(); System.out.println("The number is " + number); } public static int getRandomNumber() { int num = (int)(Math.random() * 10) + 1; return num; } }
In this program, the getRandomNumber method uses the Math.random method to calculate a random number from 1 to 10. (For more information about the Math.random method, see Book II, Chapter 3.) The return statement returns the random number that was calculated.
Because the return statement can specify an expression as well as a simple variable, I could just as easily have written the getRandomNumber method like this:
public static int getRandomNumber() { return (int)(Math.random() * 10) + 1; }
Here the return statement includes the expression that calculates the random number.
You can use a method that returns a value in an assignment statement, like this:
int number = getRandomNumber();
Here the getRandomNumber method is called, and the value it returns is assigned to the variable number.
You can also use methods that return values in expressions-such as
number = getRandomNumber() * 10;
Here the value returned by the getRandomNumber method is multiplied by 10, and the result is assigned to number.
If a method declares a return type other than void, it must use a return statement to return a value. The compiler doesn't let you get away with a method that doesn't have a correct return statement.
Things can sometimes get complicated if your return statements are inside if statements. Sometimes, the compiler can get fooled and refuse to compile your program. To explain this, I offer the following tale of multiple attempts to solve what should be a simple programming problem:
Suppose you want to create a random-number method that returns random numbers between 1 and 20, but never returns 12 (because you have the condition known as duodecaphobia, which-as Lucy from Peanuts would tell you-is the fear of the number 12). Your first thought is to just ignore the 12s, like this:
public static int getRandomNumber() { int num = (int)(Math.random() * 20) + 1; if (num != 12) return num; }
However, the compiler isn't fooled by your trickery here. It knows that if the number is 12, the return statement won't get executed. So it issues the message missing return statement and refuses to compile your program.
Your next thought is to simply substitute 11 whenever 12 comes up:
public static int getRandomNumber() { int num = (int)(Math.random() * 20) + 1; if (num != 12) return num; else return 11; }
However, later that day you realize this solution isn't a good one because the number isn't really random anymore. One of the requirements of a good random-number generator is that any number should be as likely as any other number to come up next. But because you're changing all 12s to 11s, you've made 11 twice as likely to come up as any other number.
To fix this error, you decide to put the random number generator in a loop that ends only when the random number is not 12:
public static int getRandomNumber() { int num; do { num = (int)(Math.random() * 20) + 1; if (num != 12) return num; } while (num == 12); }
But now the compiler refuses to compile the method again. It turns out that the compiler is smart, but not real smart. It doesn't catch the fact that the condition in the do-while loop is the opposite of the condition in the if statement, meaning that the only way out of this loop is through the return statement in the if statement. So the compiler whines missing return statement again.
After thinking about it a while, you come up with this solution:
public static int getRandomNumber() { int num; while (true) { num = (int)(Math.random() * 20) + 1; if (num != 12) return num; } }
Now everyone's happy. The compiler knows the only way out of the loop is through the return statement, your doudecaphobic user doesn't have to worry about seeing the number 12, and you know that the random number isn't twice as likely to be 11 as any other number. Life is good, and you can move on to the next topic.
To illustrate the benefits of using methods that return values, Listing 7-2 presents another version of the guessing game program that uses four methods in addition to main:
Listing 7-2: Another Version of the Guessing Game Program
import java.util.Scanner; public class GuessingGameMethod2 { static Scanner sc = new Scanner(System.in); public static void main(String[] args) { System.out.println("Let's play a quessing game"); do → 11 { playARound(); → 13 } while (askForAnotherRound()); → 14 System.out.println(" Thank you for playing!"); } public static void playARound() → 18 { boolean validInput; int number, guess; String answer; // Pick a random number number = getRandomNumber(); → 25 // Get the guess System.out.println(" I'm thinking of a number " + "between 1 and 10."); System.out.print("What do you think it is? "); guess = getGuess(); → 31 // Check the guess if (guess == number) System.out.println("You're right!"); else System.out.println("You're wrong!" + " The number was " + number); } public static int getRandomNumber() → 41 { return (int)(Math.random() * 10) + 1; → 43 } public static int getGuess() → 46 { while (true) → 48 { int guess = sc.nextInt(); if ((guess < 1) || (guess > 10)) { System.out.print("I said, between 1 and 10. " + "Try again: "); } else return guess; → 57 } } public static boolean askForAnotherRound() → 61 { while (true) → 63 { String answer; System.out.print(" Play again? (Y or N) "); answer = sc.next(); if (answer.equalsIgnoreCase("Y")) return true; → 69 else if (answer.equalsIgnoreCase("N")) return false; → 71 } } }
The following paragraphs point out the key lines of this program:
Open table as spreadsheet
A parameter is a value that you can pass to a method. The method can then use the parameter as if it were a local variable initialized with the value of the variable passed to it by the calling method.
For example, the guessing game application that was shown in Listing 7-2 has a method named getRandomNumber that returns a random number between 1 and 10:
public static int getRandomNumber() { return (int)(Math.random() * 10) + 1; }
This method is useful, but it would be even more useful if you could tell it the range of numbers you want the random number to fall in. For example, it would be nice if you could call it like this to get a random number between 1 and 10:
int number = getRandomNumber(1, 10);
Then, if your program needs to roll dice, you could call the same method:
int number = getRandomNumber(1, 6);
Or, to pick a random card from a deck of 52 cards, you could call it like this:
int number = getRandomNumber(1, 52);
And you wouldn't have to start with 1, either. To get a random number between 50 and 100, you'd call it like this:
int number = getRandomNumber(50, 100);
In the following sections, you write methods that accept parameters.
A method that accepts parameters must list the parameters in the method declaration. The parameters are listed in a parameter list that's in the parentheses that follow the method name. For each parameter used by the method, you list the parameter type followed by the parameter name. If you need more than one parameter, you separate them with commas.
For example, here's a version of the getRandomNumber method that accepts parameters:
public static int getRandomNumber(int min, int max) { return (int)(Math.random() * (max - min + 1)) + min; }
Here the method uses two parameters, both of type int, named min and max. Then, within the body of the method, these parameters can be used as if they were local variables.
Or you could call it like this:
int low = 1; int high = 10; int number = getRandomNumber(low, high);
Or you can dispense with the variables altogether and just pass literal values to the method:
int number = getRandomNumber(1, 10);
You can also specify expressions as the parameter values:
int min = 1; int max = 10; int number = getRandomNumber(min * 10, max * 10);
Here number is assigned a value between 10 and 100.
The scope of a parameter is the method for which the parameter is declared. As a result, a parameter can have the same name as local variables used in other methods without causing any conflict. For example, consider this program:
public class ParameterScope { public static void main(String[] args) { int min = 1; int max = 10; int number = getRandomNumber(min, max); System.out.println(number); } public static int getRandomNumber(int min, int max) { return (int)(Math.random() * (max - min + 1)) + min; } }
Here the main method declares variables named min and max, and the getRandomNumber method uses min and max for its parameter names. This doesn't cause any conflict, because in each case the scope is limited to a single method.
Here a variable named number is set to 1 and then passed to the method named tryToChangeNumber. This method receives the variable as a parameter named i, and then sets the value of i to 2. Meanwhile, back in the main method, println is used to print the value of number after the tryToChangeNumber method returns.
Because tryToChangeNumber only gets a copy of number and not the number variable itself, this program displays the following on the console (drumroll please …): 1.
The key point is this: Even though the tryToChangeNumber method changes the value of its parameter, that change has no effect on the original variable that was passed to the method.
To show off the benefits of methods that accept parameters, Listing 7-3 shows one more version of the Guessing Game program. This version uses the following methods in addition to main:
Listing 7-3: Yet Another Version of the Guessing Game Program
import java.util.Scanner; public class GuessingGameMethod3 { static Scanner sc = new Scanner(System.in); public static void main(String[] args) { System.out.println("Let's play a guessing game!"); do { playARound(1, getRandomNumber(7, 12)); → 13 } while (askForAnotherRound("Try again?")); System.out.println(" Thank you for playing!"); } public static void playARound(int min, int max) { boolean validInput; int number, guess; String answer; // Pick a random number number = getRandomNumber(min, max); → 25 // Get the guess System.out.println(" I'm thinking of a number " + "between " + min + " and " + max + "."); → 29 System.out.print("What do you think it is? "); guess = getGuess(min, max); → 31 // Check the guess if (guess == number) System.out.println("You're right!"); else System.out.println("You're wrong!" + " The number was " + number); } public static int getRandomNumber(int min, int max) → 41 { return (int)(Math.random() → 43 * (max - min + 1)) + min; } public static int getGuess(int min, int max) → 47 { while (true) { int guess = sc.nextInt(); if ((guess < min) || (guess > max)) → 52 { System.out.print("I said, between " + min + " and " + max + ". Try again: "); } else return guess; → 59 } } public static boolean askForAnotherRound(String prompt) → 63 { while (true) { String answer; System.out.print(" " + prompt + " (Y or N) "); answer = sc.next(); if (answer.equalsIgnoreCase("Y")) return true; else if (answer.equalsIgnoreCase("N")) return false; } } }
The following paragraphs point out the key lines | https://flylib.com/books/en/2.706.1/adding_some_methods_to_your_madness.html | CC-MAIN-2020-05 | refinedweb | 3,268 | 63.19 |
27 April 2012 09:16 [Source: ICIS news]
TOKYO (ICIS)--Japanese chemical producer Showa Denko said on Friday its first-quarter net profit doubled to yen (Y) 5.33bn ($65.8m) partly on the back of improved performance in the electronics segment as chemical earnings slumped.
This compares with a net profit of Y2.58bn in the same period a year earlier.
Showa Denko’s sales rose by 6% year on year to Y181.4bn in the first three months of 2012, while operating profit grew by 2% to Y9.54bn, the company said in a statement.
Operating profit at the firm’s petrochemical segment fell by 97% to Y73m in the first quarter, while sales declined by 20% to Y47.1bn, it said.
Earnings at the petrochemical segment were weighed by reduced ethylene output as its plant at ?xml:namespace>
($1 = Y | http://www.icis.com/Articles/2012/04/27/9554260/japans-showa-denkos-q1-net-profit-doubles-to-66m.html | CC-MAIN-2015-22 | refinedweb | 143 | 76.32 |
How to send an SMS from React with Twilio
Phil Nash
Originally published at
twilio.com
on
・9 min read from your React application and send SMS messages without distributing your credentials to the internet.
Our tools
For our application to send text messages using the Twilio REST API we will need the following:
- A Twilio account and phone number that can send SMS messages (you can sign up for a Twilio account for free here)
- Node.js to build our React app and to run our server (you can build the server-side component of this in any language, but in this post we're going to do so in Node so we can keep it all JavaScript)
- React Dev Tools for your browser (optional, but really useful for seeing what goes on in the application
To get started, download or clone the react-express-starter application that I built in my last blog post.
git clone
Change into the directory and install the dependencies.
cd react-express-starternpm install
In the project directory, create a file called
.env:
touch .env
You can now test the project is working by running
npm run dev. The application will load in your browser at localhost:3000.
This starter application is set up to have both a React application and an Express application in the same project that you can run concurrently. If you want to find out how this works, check out this blog post.
Building the server-side
As discussed, we need to make the Twilio API calls from the server. We'll add an endpoint to the Express server that can be called from our React application. Start by installing the Twilio Node.js module. Note: for the purposes of this application I'm saving the server dependencies as development dependencies to separate them from the client-side dependencies.
npm install twilio --save-dev
Next, we need to configure the application with our Twilio credentials. Gather your Twilio Account Sid and Auth Token from the Twilio console along with a Twilio phone number that can send SMS messages. Enter all three into the
.env file you created earlier like so:
TWILIO_ACCOUNT_SID=YOUR_ACCOUNT_SID TWILIO_AUTH_TOKEN=YOUR_AUTH_TOKEN TWILIO_PHONE_NUMBER=YOUR_TWILIO_PHONE_NUMBER
This will set your credentials in the environment. Now, open
server/index.js so that we can get started with the code necessary for sending the message. Under the other module requires at the top of the file, require and initialise the Twilio library with the credentials from the environment.
const express = require('express'); const bodyParser = require('body-parser'); const pino = require('express-pino-logger')(); const client = require('twilio')(process.env.TWILIO_ACCOUT_SID,process.env.TWILIO_AUTH_TOKEN);
We'll be sending the data to the endpoint we're building as JSON, so we'll need to be able to parse the JSON body. Configure the Express app with body parser's JSON parser:
const app = express(); app.use(bodyParser.urlencoded({ extended: false })); app.use(bodyParser.json());app.use(pino);
Make a route for a
POST request. Add the following below the route for
/api/greeting:
app.post('/api/messages', (req, res) => { });
We're going to respond with JSON too, so set the
Content-Type header to
application/json.
app.post('/api/messages', (req, res) => { res.header('Content-Type', 'application/json'); });
We'll then use the Twilio client we initialised earlier to create a message. We'll use our Twilio number as the
from number and get the
to number and
body of the message from the incoming request body. This returns a Promise that will fulfill when the API request succeeds or reject if it fails. In either event we will return a JSON response to tell the client-side whether the request was a success or not.
app.post('/api/messages', (req, res) => { res.header('Content-Type', 'application/json'); client.messages .create({ from: process.env.TWILIO_PHONE_NUMBER, to: req.body.to, body: req.body.body }) .then(() => { res.send(JSON.stringify({ success: true })); }) .catch(err => { console.log(err); res.send(JSON.stringify({ success: false })); }); });
That's all we need on the server, let's get started on the React portion.
Building the client-side
On the client-side, we can encapsulate the form to send our SMS via the server entirely in just one component. So, in the
src directory create a new component called
SMSForm.js and start with the boilerplate for a component:
import React, { Component } from 'react'; class SMSForm extends Component { } export default SMSForm;
We're going to create a form that a user can fill in with a phone number and message. When the form is submitted it will send the details to our server endpoint and send the message as an SMS to the number.
Let's build the
render method for this component first: it will include a form, an input for the phone number, a textarea for the message and a button to submit:
render() { return ( <form> <div> <label htmlFor="to">To:</label> <input type="tel" name="to" id="to" /> </div> <div> <label htmlFor="body">Body:</label> <textarea name="body" id="body"/> </div> <button type="submit"> Send message </button> </form> ); }
We can add some CSS to style this form a bit. Create the file
src/SMSForm.css and add the following:
.sms-form { text-align: left; padding: 1em; } .sms-form label { display: block; } .sms-form input, .sms-form textarea { font-size: 1em; width: 100%; box-sizing: border-box; } .sms-form div { margin-bottom: 0.5em; } .sms-form button { font-size: 1em; width: 100%; } .sms-form.error { outline: 2px solid #f00; }
Import the CSS at the top of the SMSForm component:
import React, { Component } from 'react'; import './SMSForm.css';
Now, import the component into
src/App.js and replace the render method with the following:
import React, { Component } from 'react'; import logo from './logo.svg'; import './App.css'; import SMSForm from './SMSForm'; class App extends Component { render() { return ( <div className="App"> <header className="App-header"> <img src={logo} <SMSForm /> </header> </div> ); } } export default App;
Start your application with
npm run dev and you'll see the form on the page.
The form doesn't do anything yet, so let's fix that.
Making an interactive form in React
To hook the HTML form up with the component we need to do a few things:
- Keep the state of the input and textarea up to date in the state of the component
- Handle submitting the form and sending the data to the server
- Handle the response from the server and clear the form if the message was sent successfully, or show an error if it wasn't
We'll start by setting up some initial state in the constructor. We'll need to store the form inputs, whether the form is currently being submitted (so that we can disable the submit button) and whether there was an error. Create the constructor for the component as follows:
class SMSForm extends Component { constructor(props) { super(props); this.state = { message: { to: '', body: '' }, submitting: false, error: false }; } // rest of the component }
We'll need a method that can handle changes in the form fields and update the state. We could create two methods, one for the input and one for the textarea, but since the names of the form elements and items in the state match up we can build one method to cover both.
onHandleChange(event) { const name = event.target.getAttribute('name'); this.setState({ message: { ...this.state.message, [name]: event.target.value } }); }
Note here that we use ES2015's computed property names to set the right property in the state and the spread operator to fill in the rest of the state.
We'll need to bind this method to the object to ensure that
this is correct when we use it to receive an event. Add the following to the bottom of the constructor:
constructor(props) { super(props); this.state = { message: { to: '', body: '' }, submitting: false, error: false }; this.onHandleChange = this.onHandleChange.bind(this); }
We can now update our rendered JSX to set the value of the form fields using the current state and handle updates with our
onHandleChange method:
render() { return ( ">Send message</button> </form> ); }
Reload the app and you'll be able to update the form fields. If you have the React dev tools for your browser, you'll be able to see the state updating too.
Now we need to handle the form submission. Build another function,
onSubmit, that starts by updating the
submitting state property to true. Then use the
fetch API to make the request to the server. If the response is successful then clear the form and set
submitting to false. If the response is not a success, set
submitting to false but set
error to true.
onSubmit(event) { event.preventDefault(); this.setState({ submitting: true }); fetch('/api/messages', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(this.state.message) }) .then(res => res.json()) .then(data => { if (data.success) { this.setState({ error: false, submitting: false, message: { to: '', body: '' } }); } else { this.setState({ error: true, submitting: false }); } }); }
Like with the
onHandleChange method, we also bind this method in the constructor:
constructor(props) { super(props); this.state = { message: { to: '', body: '' }, submitting: false, error: false }; this.onHandleChange = this.onHandleChange.bind(this); this.onSubmit = this.onSubmit.bind(this); }
Now, in the JSX we add the
onSubmit method as the submit handler on the form. We also set the form's class to "error" if we receive an error from the request. And while the form is submitting we set the button's
disabled property.
render() { return ( <form onSubmit={this.onSubmit} className={this.state.error ? 'error sms-form' : 'sms" disabled={this.state.submitting}> Send message </button> </form> ); }
This is all we need, so refresh the app again and enter your mobile number and a message to send. Submit the form and if the details are correct then your message will be sent, if not, the form will show that the state is in error.
Sending messages and keeping your credentials safe
Sending SMS messages from a web app is cool. Sending SMS messages from your React app without exposing your credentials is even cooler 😎.
You can check out all the code from this example application in the GitHub repo.
Now that you have the basis of a React app that can send SMS messages you could make some improvements. First would likely be better validation and error messages. With a similar design you could add phone number lookups, generate phone calls or implement two factor authentication right from your React app too.
I’d love to hear about the app you’re building with React. Drop me a comment below, hit me up on Twitter at @philnash or send an email my way at philnash@twilio.com.
I'm a frontend developer. Or am I?
As a frontend developer, I've always found it difficult to draw the line betwee...
Hi, I keep on getting this error:
Proxy error: Could not proxy request /api/messages from localhost:3000 to localhost:3001/.
See nodejs.org/api/errors.html#errors_... for more information (ECONNREFUSED).
How to solve?
Oh, that's interesting. Are you running the server with
npm run dev? Are there any other errors in the terminal?
Yes I am. No other errors in the terminal
Have you filled in the
.envfile with your credentials? And ensure you're not using test credentials?
What's the code you have for the
/api/messagesendpoint right now?
Does Twilio support the live broadcast feature? as I am developing an application like BigOlive or Atompark. so before making the purchase, I need to know and view good respond.
I guess you're asking about Twilio Video? If so, it's not built for broadcasting video streams to many watchers. The primary use for it is for 1 on 1 and group conversations over video, with a maximum room size of 50 people.
Hope that helps!
Is Twilio completely free of charge i we use it in production apps
Twilio is not free of charge, no. There is a trial account that you can use to test with, but if you want to run with Twilio in production you will need to pay for it. You only pay for what you use though, check out the pricing here.
What are you using it for? | https://dev.to/twilio/how-to-send-an-sms-from-react-with-twilio-18gn | CC-MAIN-2019-35 | refinedweb | 2,046 | 64.61 |
It works!
Hi, I've had big success with your software. Bought a gps and it works perfectly!
I haven't found anyone else that has posted a picture with a working heat map, feel free to use it if you are unable to make one yourself. Thank you for spending the time developing this awesome free software. I've sent a small donation your way...
Re: It works!
Hi Tobby,
Thanks for posting this, it's interesting to see how this works in the field as I a unable to test it myself.
From your test and others that I've been sent it seems to do the job. I've added some features recently which should make scanning easier; the 'Start' and 'Stop buttons can now be changed to 'Continue' and 'Stop at end' which means you can move to a location make a few sweeps at that point then continue the scan at another location. The more locations you survey will increase the accuracy.
The mapping can't distinguish 'real' signals from reflected paths so I would expect you'd get better results in less built up areas and with higher frequencies where line of sight propagation is dominant. A few users have mapped mobile phone transmitters in their area and it does seem they get better results with the 4G 1.7 - 2.1GHz bands than the GSM bands on 800MHz or thereabouts.
Finally thank you for the donation, they all add up and allow me to spend time on FOSS projects which I really enjoy.
export map gps 600km2... OK
HELLO TOBBY ,
FOR YOUR INFORMATION, I HAVE MADE A CARD HOT POINTS OF MY REGION WITH THE SOFTWARE RTLSCANNER THE FRIEND AL. CARD NOW COVERS AN AREA OF 600 WITH A KM2 SCAN ANY BAND A 55 MHZ 1000 MHZ. WHY I HAVE TO HAVE 4 CAMPAIGNS FIELD MEASUREMENTS WITH A TOTAL OF ABOUT 90 POINTS FOR FIXED MY RECORDS TOGETHER AND THEN THE 4 BACKUP FILES IN ONE ... IT WORKS VERY WELL AND IT IS POSSIBLE FROM FILE BACKUP SCAN TO PUBLISH IN EXPORT MAP GPS MAPS OF ANY RATE OF LOCAL STATIONS WITH A SUITABLE CHOICE FOR MODULATION OF STATION FOR BANDWIDTH. I WANT SOME IMAGES AVAILABLE TO YOU: ... WRITE ME TO MY EMAIL ADDRESS PERSONAL [email protected]
THANKS PASCAL
Problems running rtlsdr_svan.py
Al:
Thanks for this cool tool.
I seem to have a problem, when I run "python rtlsdr_scan" I get an error I cannot solve.
ImportError: No module named tools.list_ports
Can you shed some light on this problem?
I ran "python rtlsdr_scan_diag.py" and it says:
"No problems found"
Thanks,
Freddie
Problems running rtlsdr_svan.py
Al:
Typos problems:
"ImportError: No module named tool.list_ports" should be "ImportError: No module named serial.tools.list_ports"
Thanks,
Freddie
Re: Problems running rtlsdr_scan.py
Hi Freddie,
Can you go to 'Help->System Information' and post the output? Usually this error is due to an out dated version of pySerial.
Thanks
I'm afraid I don't understand
I'm afraid I don't understand this statement:
"go to 'Help->System Information'
This Does not exist on the system I'm working on.
This system is a CubieTruck ARMHFV7i running Ubuntu 12.04 LTS. The window manager is LXDE.
Python version is 2.7.3
I did a locate pySerial and it comes up with nothing.
Have I do something wrong? Do I need to install something else?
Thanks,
Freddie
Re: I'm afraid I don't understand
Hello,
The 'System Information' item is available in the scanners 'Help' menu.
It's possible that PySerial is not installed or an older version, in which case run the following in a terminal:
sudo apt-get install python-serial
Hope that helps.
I'm afraid I don't understand
Al:
I found the problem.
It appears that pip installed to /usr/local/lib/python2.7/site-packages, however the PYTHONPATH was pointing to /usr/lib/python2.7/site-packages. The /usr/lib/python2.7/site-packages version of serial doesn't have the all the pieces of pySerial so I got this error.
I fixed it by removing the PYTHONPATH from my .bashrc file and it works just like it should.
Kinda weird huh?
Thanks,
Freddie
Re I'm afraid I don't understand
Strange, my guess is that somewhere an installation has added that. Full points for finding it!
Multiple peaks?
Is there a way to show multiple peaks. When I scan a range it only shows the highest one. Would be awesome if you could set a threshold in dB and show X's with the specific frequency on anything above that level.
Please let me know if I am missing something. I have to mouseover on all but highest to see what freq. And that isn't very accurate as the default mouse pointer is a fat finger :)
Thanks
Re: Multiple peaks?
Hi Larry,
I'm looking into a way to mark multiple peaks, I'm currently experimenting with a few methods of achieving this and will hopefully have a solution soon.
As for the fat finger, the scanner starts up in mouse panning mode, if you click the 'Pan' button (the 4 joined arrows on the toolbar) it will revert to a pointer.
can't launch.. errors
i keep getting
(python:9007): GLib-CRITICAL **: g_hash_table_insert_internal: assertion 'hash_table != NULL' failed
Traceback (most recent call last):
File "./rtlsdr_scan.py", line 119, in
frame = FrameMain(APP_NAME, pool)
File "/home/gareth/src/RTLSDR-Scanner/src/main_window.py", line 169, in __init__
self.__create_widgets()
File "/home/gareth/src/RTLSDR-Scanner/src/main_window.py", line 195, in __create_widgets
self.graph = PanelGraph(self, self, self.settings, self.status, self.remoteControl)
File "/home/gareth/src/RTLSDR-Scanner/src/panels.py", line 110, in __init__
self.create_plot()
File "/home/gareth/src/RTLSDR-Scanner/src/panels.py", line 263, in create_plot
self.toolbar.set_type(self.settings.display)
File "/home/gareth/src/RTLSDR-Scanner/src/toolbars.py", line 502, in set_type
self.__set_func()
File "/home/gareth/src/RTLSDR-Scanner/src/toolbars.py", line 402, in __set_func
self.ToggleTool(buttons[self.settings.plotFunc - 1], True)
File "/usr/lib/python2.7/dist-packages/wx-2.8-gtk2-unicode/wx/_controls.py", line 3875, in ToggleTool
return _controls_.ToolBarBase_ToggleTool(*args, **kwargs)
TypeError: in method 'ToolBarBase_ToggleTool', expected argument 2 of type 'int'
Re: can't launch.. errors
Hi, this should be fixed in the latest version.
Thanks
--remote option working?
Can you check if the remote option is working correctly? I run rtl_tcp on my Mac and run rtlsdr_scan.py with -r 127.0.0.1:1234 but i get a usb_claim_interface error -3.
Re: --remote option working?
Hello,
Are you seeing the error from rtl_tcp or from the scanner?
ImportError: No module named PIL
I am unable to get rtlsdr_scan.py to run after install. This is a first time install There are no errors from rtlsdr_scan.py. The OS is Windows 7 Professional. The rtlsdr_scan.py command window shows something like the following. Suggestions?
Traceback (most recent call last):
File "C:\Program Files (x86)\RTLSDR Scanner\rtlsdr_scan.py", line 54, in
from cli import Cli
File "C:\Program Files (x86)\RTLSDR Scanner\cli.py", line 36, in
from file import save_plot, export_plot, ScanInfo, File
File "C:\Program Files (x86)\RTLSDR Scanner\file.py", line 37, in
from PIL, import Image
ImportError: No module named PIL
ImportError: No module named PIL
That should have said "...There are no errors from rtlsdr_scan_diag.py..." Sorry, brain got ahead of fingers.
ImportError: No module named PIL
Looks like the Windows installation for rtlsdr-scan failed to install PIL. I installed PIL manually and rtlsdr-scan.py starts up now. Perhaps a check for PIL needs to be added to rtlsdr_scan_diag.py?
I'm looking forward to learning more about your rtlsdr scanner package. Thank you for creating it.
ImportError: No module named PIL
Thanks, I've added check to rtlsdr_scan_diag.py but I'm still trying to work out why PIL wasn't installed in the first place.
Enabling sub 24 MHz on R820T USB tuner
There is a new RTLSDR.dll file that can allow an R820T USB tuner to go down as low as 4 or 5 MHz. Performance may not be as good as a real expensive wideband SDR that low, but it does receive lower frequencies. This works great in SDRSharp but if I put this DLL in the directory with this program, it does not enable low band scanning. I am trying to check the noise floor on CATV return path which is normally 5-42 MHz and without this modified open source DLL, I can only use this application to check 24 MHz and up.
Is there any way to build this application with support for the lower frequencies? Here is the original article I followed to get the new DLL that enables the direct sampling modes for pre 24 MHz tuning in this dongle:
Thank you for your help!
Enabling sub 24 MHz on R820T USB tuner
Thanks for the info, I tried the new DLL with the stock antenna which was very good at picking up my PC but otherwise I didn't have any problems.
As for your problem I wonder if the pyrtlsdr library is looking at a different DLL, I've updated
rtlsdr_scan_diag.pyto show the location of the driver that's being loaded as it may not be the one in the installation directory.
db/√Hz
Hi Al,
Firstly, huge thanks for writing an amazing program - much more intuitive and useful than SDR# as a wideband scanner. My question relates to the calculation of received power. I have been searching for a way to convert this figure to dBm so I can refer data collected in RTLSDR Scanner to another scanner that collects data in dBm. I guess I am showing my lack of technical understanding - but I have been searching for days on the internet and can't find any information - could you possibly point me in the right direction? Also wondering if you would consider re-writing some parts of the program for a commercial arrangement?
db/√Hz
Thanks Fraser glad you find the software useful, in fact I'm surprised at how many people do!
The reason I use dB/√Hz is really to reinforce the fact that this software uses Power Spectral Density analysis to transform the received bandwidth from the time domain (i.e. amplitude vs. time) to the frequency domain (amplitude vs. frequency), as many programs use a standard FFT instead. PSD has a few advantages especially when it comes to stitching frequency ranges together.
The square root can be ignored as the analysis is scaled to 1Hz, basically meaning that the value is the power of a particular frequency per unit frequency.
On top of this the dBm unit is the ratio of power referenced to 1mW (decibels are just a ratio, not a unit) and the gain of dongles is not created equal (even sometimes between identical dongles).
Because of this I decided to use ratios (the decibel) rather than an absolute unit (dBm) because of the variation in tuners.
To sum-up: treat dB/√Hz as just decibels (e.g. a signal which is 6dB lower than another is about half the power); don't worry about it as an absolute value.
It does all what is missing to SRD#
Even it is very long to install and requires also to install PYTHON, this nice software is very useful and does a lot of functions that they are missing to SDR# :
- A large frequency spectrum is displayed
- The mean envelope curve of the spectrum is continuously updated
-...
Like SDR# it is able to work with an upconverter displaying the true tested frequency.
For the hobbyist it opens the door of the frequency spectrum analysis.
It does all what is missing to SRD#
Thanks,
Glad you like it and find it useful, my hope was that hobbyists (like myself) would benefit from a cheap spectrum analyser.
Python does has it's disadvantages and originally I was thinking about using C++ (for speed) but I chose it because:
- I wanted to learn Python
- I didn't envisage that it would be anything more than a simple script
- The matplotlib library greatly simplifies plotting, looks great but only supports Python
- It runs on multiple platforms
In retrospect not the best of reasons but porting it to another language would be a major undertaking.
It's simply great !
I have built a little homebrew noise source to experiment some stuff with an USB dongle and a 125MHz upconverter and with RTL SDR Scanner :
- A video amp salvaged from the trash from 0 to 30MHz : strange no flat BW with several peaks
- An old MFJ all SW bands preamp antenna from 0 to 30MHz : the gain curve is clearly visible, but the frequency dial of the MFJ is not reliable
- The upconverter itself from 0 to 100Mhz : the BW is as expected from 0.5 to 65MHz
- An experimental pass-band filter 2X L=1uH C=270pF coupled with a 10pF : we can see the two peaks like camel bumps
- ...
It is tricky to tune it with the LC circuits, but you can do it with some patience, playing with the gain and attenuation, and having some care in order not to damp the LC circuit
I don't understand all the commands and what sometime it bugs, but I'm really impressed by the offered possibility of this program !
It's simply great !
Thanks a lot! I'm glad you find it useful.
You're experiment sounds interesting, I really should build a wideband noise source and document some results with various filters and oscillators.
When you find bugs you can post a quick description of them in these comments and I'll try and fix them.
A noisy sardines tin
Hi Al,
Find here my modest and noisy experiments under the nick name ALZ, sorry it's in French :
Half of the parts come from recycle i.e. : transistors, shield, epoxy breadboard, battery connector ...
The first transistor in reverse biasing acts as a Zener diode, this is actually the noise source, you may try some NPN transistors to find a noisy one, better with an oscilloscope you can see the starting voltage of noise (Zener bend), the reverse voltage should be about 9V ...
The noise is detected from few KHz to 1GHz upper limit of my USB dongle, sure it's not very flat or calibrated like a professional one but it's not too bad for a one pound source.
I hope it can help someone.
Antoine
Windows 7 and bugs ...
Sorry I forgot about the bugs, I don't know, maybe is my Windows 7 PC :
- When you clear the screen you can restart the program but it display anything on the screen.
- Sometimes after several sweeps the program freezes.
I don't understand what OBW means and what it does when you click on it?
Windows 7 and bugs ...
Thanks,
I'll look into both problems, I'm aware of the freezing issues but have had no luck so far with it.
OBW is an acronym for 'Occupied Bandwidth', it's a measure of the frequency range that contains 99% of the total power.
Select part of the spectrum by dragging the middle mouse button and tick OBW, you may have to alter the range to get a sensible result.
I like your approach to the noise source, especially the reverse biased base-emitter - my junk boxes are always my first port of call when building anything.
HackRF
Al:
I now have a HackRF and I was wondering if the Scanner will work with HackRf? It is part of the osmocom library, but RTLSDR Scanner does not seem to find it.
Thanks,
Freddie
HackRF
I've had quite a few requests for the HackRF and AirSpy support but I simply can't afford to buy either of them, I have had some kind offers of loan devices but I'm not keen on adding support for a device that I won't always have access to.
My software uses the specific Osmocom RTLSDR driver (via the pyrtlsdr driver) which doesn't support the HackRF. I think the library you mention is gr-osomosdr which works with GNU Radio, I chose not to use this as it would make my project dependent on GNU Radio, which in turn can be difficult to set up.
modify the program
Hello,
I am a college student that is trying to have a program to connect to a synthetic aperture radar system like the system done by MIT but slightly modified by using a dongle instead of recording a wave file. (see... for details on the project) I have been combing through the code for weeks and I haven't been able to find a way to add something to your program.
Here's what I want to do: I just want to add an option to the display drop down menu that can calculate ranging and SAR that I will code. The scanner would also have to focus on audio frequencies because of the nature of the device.
If you could just give me some pointers on where I could begin that would be great! And just so you know this is only for educational purposes and will not be mass distributed or sold. Please let me know if you are interested in helping.
Thanks!
modify the program
I'm also fairly new to programming and only know the basics of a few languages. I have resources for help, but because I am somewhat unfamiliar with python I have found this as a difficult challenge. Any tips are greatly appreciated!
modify the program
Hello,
Thanks for the interest, but I think modifying my software to do this will be an uphill struggle. The main reason is that my program is based around spectrum analysis of a radio frequency signal whereas the SAR approach is in the audio range. Furthermore to produce an image the software needs to know where the RADAR module is located to produce the output.
If you don't have access to MATLAB you maybe able to use GNU Octave. I used matplotlib in my software to perform calculations but mainly to produce the graphs and I would definitely recommend it, although you will need to get to grips with Python.
As for learning Python, Google is your best bet. For matplotlib there's a good beginners guide.
Neat Software!
Very nice software. After numerous hoops to jump through, have the scanner working on a HP Elitebook 8440p laptop running Linux Mint.
Being a ham for 35 years+ I'm sure I'll find many uses for the R820 rtlsdr dongle and this great scaninf software. One needs to be very persistant when trying to get the rtlsdr dongle working with various software! However the payback is very good with a $15.00 dongle and the developers fine software out for them. Thanks for this great piece of software and I cant wate to get into the manual.
one good use I can think of already is checking for second harmonics of Amatuer equipment!
Beholding to developers like you
Robert D. Houlihan, N9DH
Neat Software!
Hi, thanks very much but a be warned; the manual is very out of date, but I hope to get it up to speed soon. For the moment I recommend you just play around with it.
If you have any difficulties please post another comment and I'll get back to you.
Stray lines
Hello Al,
I have used RTL SDR SCANNER with an +125MHz upconverter, and I have tested it with two different sinus generators from 0 up to 30MHz, but on the spectrum results, there is always a stray line above each wanted signal lines at exactly +250kHz.
First I suspected my generators (but both with the same symptom doesn't look possible), then the up-converter to do these parasitic lines, but using only the USB dongle (since it starts from 24MHz), the stray lines are still there.
Do you know what could cause that?
Is it due to the program, the sound card or the USB dongle?
Stray lines
Hello Antoine,
The 250kHz lines could be something to do with the way the software attempts to flatten the frequency response. If you click on 'Edit -> Radio devices' the 'Band offset' defaults to 250kHz. You can click this number to change it which may help.
It also might be due to a high input signal overloading either the upconverter or the dongle, either way I'd be interested to hear back if you have any luck with it.
Stray lines
Actually, I wanted to attempt to calibrate the dB/Hz spectrum scale in dBm/Hz with a sine generator, measuring the Vpp output signal on a 50 Ohms resistor load and calculating the dBm power, I found that the spectrum scale is about dBm =dBscale -28dB (with 0dB of gain to have a reference).
Playing with the generator's attenuator (with two levels -16dBm -36dBm), shows that the relative dBLog10 scale works well.
Because I don't have a HF wattmeter to compare, this measurment is not very accurate, I don't know exactly where the 0dBm could be (I suppose it depends on the dongle and the upconverter gains).
I don't know whether -36dBm overload the USB tuner dongle, I haven't found any datas about it; since the upconverter has clipping input diodes I suppose that a 0.01Vpp should not overload it too much, if I'm not wrong it can accept +1dBm before distortion.
One thing is shure is that, except the harmonics, the generator has only one main sine signal, I tested it with my Sony ICFSW7600GR radio in SSB mode, which is selective and accurate enough to hear a parasitic signal.
Thanks for your advices, I will try to play with the "offset" next time, and I'll come back with the results.
Stray lines partially solved
Hello Al,
I'm not completely satisfied with my last experiments :
1- I've tested the USB dongle alone (without the upconverter) at the same levels as before, and the positive result is the stray lines doesn't come from the converter.
2- Reducing the generator level makes disappear these parasitics lines.
3- Turning the generator OFF, and closing the input antenna of the dongle with a 50 ohms plug, and 0dB gain, but with 0KHz offset makes reappear the stray lines with a higher level and regularly at each 250KHz !
4- Putting 1KHz to 200KHz for the offset solve the problem and suppress these lines ...
I have also tested the dongle with SDR# and with a high level signal there is also parasitic lines like AM side bands.
I think you are right, the problem should come from an overloading of the USB tuner.
Could you explain what the offset does?
Has it an effect to the tuner bandwith?
I have read the manual, and honestly I didn't understood very well this function.
Antoine
Stray lines partially solved
Hello,
From your experiments it does sound like there's an issue with interference, probably from the dongle or the USB bus, these dongles are prone to it. Some people have tried shielding them or adding USB filtering to lower the noise.
The software attempts to get a flat frequency response from the dongle by taking 2 regions from the captured spectrum and averaging them.
To set this, go back to the 'Scan Offset' window, disconnect the antenna and replace it with your 50ohm load. Then click refresh and adjust the offset so the green areas cover the flattest parts of the spectrum. Typically there will be a spike in the middle the the response will roll off at the edges, 250kHz was chosen as it seems to work well with most tuners.
My FC0012 has a few spikes in this range so I find a 360KHz offset is better.
Setting the offset has no effect on bandwidth as this stays constant, it only affects which part of the spectrum is used for generating the plot.
Hope that clears things up a bit.
Stray lines pratically solved
Hello Al,
Thanks for your comments and clarifications, and spending time about it; today I have better results and perhaps what causes my problem :
Maybe overloading the USB stick (mine has a R820T) triggers the stray spikes but for me this is not the only cause, I've noticed that adjusting the offset to 0KHz causes lines each 250KHz on the whole swept band, and precisely snapped on the grid (125.000MHz, 125.250, 125.500, 125.750 etc...).
Adjusting the offset to about 200KHz, I've tested these following functions with good results, and reduced the spikes down up to the dongle's noise floor (-48dB) :
- Increasing the time Dwell >131ms
- Increasing the FFT >4000-8000
- Increasing the PSD Overlap (different to 0, about 33%)
- Changing the window function
That makes me think it could be a kind of resonance or oscillation, not electrical but "mathematical" like a repetition in a serie, but where, in the program, in one digital component? I can't explain that, I have not enough knowledge, but maybe a pinch of random or of negative feedback in the calculations could solve that.
Antoine
Stray lines
Good to hear you're results, it's the first time someone has told me of their results, thank you.
I'm a bit wary of using absolute measurements as the gain does vary with the type of tuner in the dongle and it does appear that in some there is a certain amount of AGC even at 0dB gain.
I'm really not sure of input levels as the datasheets* are not available, I'm sure the signal will be clipped way before the input diodes start conducting.
With a suitable signal generator and oscilloscope you could probe the I and Q outputs of the tuner to see when clipping appears. Otherwise use something like SDR#, turning up the input signal and watch for odd harmonics of the input, to give you a rough idea of levels.
*The maximum input level of the E4000 tuner (now obsolete) is 10dBm, but this the maximum rating before destroying the LNA, not the dynamic range.
Is it possible to use this soft with Ettus N210 SDR?
Hi Al,
I install your software on my PC with Linux OS.it was so good and i find it very useful.
how i can use this software with N210 instead of RTLSDR?
Thanks
Ehsan
Is it possible to use this soft with Ettus N210 SDR?
Hi Ehasn,
Unfortunately not. I'd like to get my hands on some of the Ettus kit but my pockets aren't deep enough for that, hence why I got into using cheap dongles.
Pillow missing from windows installer
Hi, tried to install using the windows RTLSDR installer but it fails to install "pillow".
Found the Pillow software but I cant find any instructions on how to install it manually into windows.
Any ideas would be appreciated.
Still problems
Found a windows pillow installer and RTLSDR now runs but stops on a command screen with message
DLL load failed %1 is not a valid win32 application
Error importing libraries
Any ideas would be appreciated
Still problems
Sounds like something is broken! It might be worth running the installer again using the 'Full installation' option. Otherwise try uninstalling Python and it's libraries and starting again. Unfortunately the error message doesn't give any clues about where the problem comes from.
Which version of Windows are you using?
Pages
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Str
Struts Dispatch Action Example
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Use MATLAB Arrays in Python
To use MATLAB® arrays in Python®, you can either install the Python engine before running your packaged application, as described in Install MATLAB Engine API for Python, or use
import mypackage before
import matlab in the following
programs.
The MATLAB Engine API for Python provides a Python package named
matlab that enables you to call MATLAB functions from Python. The
matlab package provides constructors to create MATLAB arrays in Python. It can create arrays of any MATLAB numeric or logical type from Python sequence types. Multidimensional MATLAB arrays are supported. For a list of other supported array types, see Pass Data to MATLAB from Python.
Examples
Create a MATLAB array in Python, and call a MATLAB function on it. Assuming that you have a package named
mypackageand a method called
mysqrtinside the package, you can use
matlab.doubleto create an array of doubles given a Python list that contains numbers. You can call the MATLAB function
mysqrton
x, and the return value is another
matlab.doublearray as shown in the following program:
import matlab import mypackage pkg = mypackage.initialize() x = matlab.double([1,4,9,16,25]) print(pkg.mysqrt(x))
The output is:
[[1.0,2.0,3.0,4.0,5.0]]
Create a multidimensional array. The
magicfunction returns a 2-D array to Python scope. Assuming you have method called
mysqrtinside
mypackage, you can use the following code to call that method:
import matlab import mypackage pkg = mypackage.initialize() x = matlab.double([1,4,9,16,25]) print(pkg.mymagic(6))
The output is:
[]] | https://kr.mathworks.com/help/compiler_sdk/python/use-matlab-arrays-in-python.html | CC-MAIN-2022-21 | refinedweb | 262 | 50.02 |
On 08/30/2013 12:43 PM, Eric Blake wrote: > On 08/30/2013 10:03 AM, Cole Robinson wrote: >> When passing in custom driver XML, allow a block like >> >> <domain xmlns: >> ... >> <test:runstate>5</test:runstate> > > Since the enum virDomainState is part of our public API, I'm not worried > about the numbers ever being tied to the wrong state. But wouldn't it > be nicer for the XML to use a string conversion of a name, rather than > just a raw number? On the other hand, this is just for testing > purposes, so I can live with it. > Yeah I think for something like this the only people who will use it are capable of getting the domain state numbers, and it keeps the code simpler. >> </domain> >> >> This is only read at initial driver start time, and sets the initial >> run state of the object. This is handy for UI testing. >> >> It's only wired up for domains, since that's the only conf/ >> infrastructure that supports namespaces at the moment. >> --- >> src/test/test_driver.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++---- >> 1 file changed, 84 insertions(+), 7 deletions(-) >> > >> + >> + tmp = virXPathUInt("string(./test:runstate)", ctxt, &tmpuint); >> + if (tmp == 0) { >> + if (tmpuint >= VIR_DOMAIN_LAST) { >> + virReportError(VIR_ERR_XML_ERROR, >> + _("runstate '%d' out of range'"), tmpuint); >> + goto error; >> + } >> + nsdata->runstate = tmpuint; > > Should we also reject VIR_DOMAIN_NOSTATE? But isn't it a valid state? I know xen used to return it quite a bit but that was ages ago. But if any libvirt version returned it then it's useful for apps to test. > >> + }; >> + >> + /* All our XML extensions are write only, so we only need to parse */ > > Maybe s/write only/input only/ > > ACK, but not until after the release. > Thanks, pushed now with that change. - Cole | https://www.redhat.com/archives/libvir-list/2013-September/msg01521.html | CC-MAIN-2016-26 | refinedweb | 287 | 70.84 |
Introduction to Flask debug mode
Flask debug mode is defined as a module that ensures insights regarding debug pushed as an extension for Flask during development of Flask application. This capability is incorporated as a part of development tools in developing any Flask application in a development server and option to enable it in production environment as well. the interactive traceback is one of the many great insight which allows any developer to look back into the code and asses what went wrong in order to effectively improve and fix the code. One effective and often known to be a best practice is to use debugger in development environment although one can also choose to use it in production, but only use it temporarily!
Why do we need a flask to debug mode?
In order to effectively find and eliminate errors in the application being developed we need the debug mode the most so that once the errors are fixed the application can qualify to be the most valuable product and bug free application increases its own value immensely. Not only that the debug mode helps to improve the code quality but also helps you reach to a point in the code where there might be a possible break of the code.
Let us know about possible errors through a simple example. In our code there is a mathematical calculation where we divide 2 numbers. Let us say that in some situations the denominator be zero. In this case the integer datatype might be incapable of handling such scenarios. Now, in a code where there are multiple modules, if is nearly impossible to find where the error has been arising from and even at a higher level, what is the error. Now in case of Flask server, if the debug mode is not ON, we would just see an error code like 404 or in some cases be Internal Server error etc. Now, finding out the type of error and where the error has generated is a herculean task! Now, in case of running the code with debug mode ON in Flask we will be able to traceback where the error has occurred and also what the error is.
Flask server also provides an interactive tool to actually know what the value before the error was, has been encountered as it has the utility of executing python code from the browser and using that interactive tool one can easily get into the most granular level to find the issue and then fix it. Now, as a best practice we should never use debug mode in production. The reasons are as follows:
- The main and the foremost reason is performance. When one uses debugging mode, there are chances of significantly slowing down the execution speed as the RAM utilization increases.
- The next reason is a security breach which might be possible in case of using debug mode although there is a PIN attached to tracebacks, but possibility of security breach does exist and that too in production data!
How does Flask debug mode work?
It is now time for us to look into the working of Flask debug mode as by this time we know the need of Flask debug mode. For the reference we will be using excerpts from built-in debugger of Flask application server i.e. Werkzeug development server. The in-built debugger is recommended to be used only in case of development stages. In production environment debugger allows execution of arbitrary python code and though protected by PIN can’t be relied on for security.
First, we would need to set the environment to development by setting the FLASK_ENV variable. this is done by executing:
set FLASK_ENV=development
Once this environment is set the debugger will automatically pop-up, when an error occurs. Another way on how we can enable the debug mode is by passing debug=True in the python code itself. Now when a debugger is running, when an error is encountered, it starts from the line of code tries to trace it back to the main function. In this way we can get a full traceback of the where the error has happened and all the subordinate function under which the piece of the error performing code is lying in.
Apart from the in-build debugger, we do have provision of using eternal debuggers for Flask application as deemed fit in accordance to the utility!
Advantages and disadvantages
Not every concept is perfect and hence consists of pros and cons. Let’s review the pros and cons of Flask debug mode here:
Advantages
- Flask Debug mode allows developers to locate any possible error and as well the location of the error, by logging a traceback of the error.
- The Flask debug mode also enables developers to interactively run arbitrary python codes, so that one can resolve and get to the root cause on why an error happened.
- All the utilities of debug mode allow developers to save time and energy.
- In addition to the traceback, the text which an error points, enables easy interpretations!
Disadvantages
- Flask’s debug mode, if left switched on in production leads to performance issues.
- In production, usage of debug mode can lead to security issues, as one can run some arbitrary python codes to hack into sensitive “production” data.
- Limited usage to development environment only!
Examples
Here are the following examples mention below
Example #1
Running with Environment as development:
Syntax (debugMode.py is a python code that contains a flask application)
In the command line:
set FLASK_ENV=development
python debugMode.py
Output:
Example #2
Running with Environment as production:
Syntax (debugMode.py is a python code that contains a flask application)
In the command line:
set FLASK_ENV=production
python debugMode.py
Output:
Example #3
Running with error in code:
Syntax (debugMode.py is a python code that contains a flask application with deliberate error)
In python code:
from flask import Flask
appFlask = Flask(__name__)
@appFlask.route('/home')
def home():
result = 10/0
return 'We are learning HTTPS @ EduCBA'
if __name__ == "__main__":
appFlask.run(debug=True)
Output:
Conclusion
Herewith this article, we have got an essence of how a debugger works and its advantages and disadvantages owing to the usage of the debugger in the development server. We also looked at a deliberate error to understand the stack trace of the error, particularly pointing out the point of generation of error!
Recommended Articles
This is a guide to Flask debug mode. Here we discuss How does Flask debug mode work along with the examples, advantages, and disadvantages. You may also have a look at the following articles to learn more – | https://www.educba.com/flask-debug-mode/?source=leftnav | CC-MAIN-2022-05 | refinedweb | 1,111 | 50.26 |
This class is a master class for a Tabular input manager.
It has been tought to be used in scenarios where you have a one-to-many relationship.
The interface should present an interface for collect the data of the one, and zero, one or many rows for collect the many.
In the hypothesis that we have to insert a ClassRoom with many Students, we will create a StudentManager by extending Tabular input manager:
class StudentManager extends TabularInputManager { protected $class='Student'; public function getItems() { if (is_array($this->_items)) return ($this->_items); else return array( 'n0'=>new Student, ); } public function deleteOldItems($model, $itemsPk) { $criteria=new CDbCriteria; $criteria->addNotInCondition('id', $itemsPk); $criteria->addCondition("class_id= {$model->primaryKey}"); Student::model()->deleteAll($criteria); } public static function load($model) { $return= new StudentManager; foreach ($model->students as $item) $return->_items[$item->primaryKey]=$item; return $return; } public function setUnsafeAttribute($item, $model) { $item->class_id=$model->primaryKey; } }
In this class we implement all methods needed for manage the primary keys of the students, for load the student of a class, for delete students.
The typical controller code for use this manager is:
~~~ [php] /** * Update a new model. * If creation is successful, the browser will be redirected to the 'view' page. */ public function actionCreate() { $model=new ClassRoom; $studentManager=new studentManager();
// Uncomment the following line if AJAX validation is needed // $this->performAjaxValidation($model); if(isset($_POST['ClassRoom'])) { $model->attributes=$_POST['ClassR
Total 20 comments
I have created a demo at
Is there a git sample for this?
I looked at and it seems partial. What is the contents of _formDetail?
It seems to be an excellent extension, but sadly I cant get it ot work. I am having a problem just at the moment of creating the Manager $students = new StudentManager(); Not a thing is showed (blank page). And the last line of debugging doesnt show anything related (15:56:31.702699 profile system.db.CDbCommand.query
end:system.db.CDbCommand.query(SHOW CREATE TABLE
examen_caso)) Any idea? Really need quickly help luis_alejandrop@hotmail.com thanks in advanced
Hi anilherath.
My php config didn't raise the exception you got, so I never experienced this error.
My suggestion is to make static the load function by adding "static":
In the example is now correct, I am pretty sure that you copied some old example without the static declaration.
Dear Dastra,
Thanks for the reply. But I followed the provided codes in GITHUB which contain the loadmodel function.
In my scenario I have Children and their Families. And this is my family manager:
My php version is 5.2 and I am using GIIx generated models and CRUD s.
@anilherath - there was an error in the documentation - it's now been corrected.
The StudentManager should have the following load function:
with no "static"
Hi,
I tried to implement this solution as exact as you explained. But I am receiving the error;
// Fatal error: Cannot make non static method TabularInputManager::load() static in class FamilyManager in ..............
//
I have updated the extension and added the enhancements described in,
I have also resurrected the code examples from above, and updated the documentation.
You can find it all on github:
Thank you both fran1978 & Zaccaria.
Zaccaria, this is a marvellous extension. I have been digging my mind and tried several things which were not to my satisfaction.
Thank you very much. I tried it and it works when I create the primary model (classroom in the example that Zaccaria gave). I would like to do some additional operations and am trying with some difficulty because I am new to PHP and newer to Yii. I am trying to understand the code but there are some parts that are not too clear. If you can spare some time, could you please guide me to do the following:
I would really appreciate if you could help me. Thanks
Blanca is right, you can place the file wherever you want, just include when you use it.
As it is supposed to be a masterclass, you can avoid to add it to the global imports and simplty include when needed:
Hello Bianca, I am just a user of ztabularinputmanager.php, but I think I can help you. I have placed this file in the folowing path: my_application\protected\extensions\
Then, in the main configuration file (my_application\protected\config\main.php), I have added the TabularInputManager extension to the 'import' array:
@Zaccaria,
Can you please tell me where to place the tabularinputmanager.php?
Hi... First Of all thanks for g8 extension and tutorial... but i would like to say one thing here that it will be so much helpful to users if you add information like in which file u have to add this code or if u need to create new file then where...? it will be so much helpful to users who are bigginer and dont know much about yii classes... share the knowledge it can help others...
In TabularInputManager class definition, last method is:
I got the error:"Static function TabularInputManager::load() should not be abstract". I took out "static" from load method definition and now it works perfectly. I left it like this:
I think that abstract static class methods are not allowed any more. You can see an explanation in this link:
ztabularinputmanager doesn't work in php5.3,php error:"Static function TabularInputManager::load() should not be abstract".Anyone can help me,please?Thanks
The table in question is a pivot for the relationship MANY_MANY. Therefore would not add a primary key autoincrement. This issue was discussed this topic:
With a small change in the code I solved the problem of working with composite primary keys.
This component has not been tought for work with composite primary key, you can simply add a foreign key autoincrement and solve all your problem.
The deleteOldItems has been created for avoid to delete and recreate the records each times. If you want to enhance, you should save all the composite primary keys in an array during the save(), then in the delete old items you should create a query that deletes all items but the just saved.
In a word: add the primary key autoincrement and solve all your problems... :)
To become more flexible, I suggest that the call to $ this->deleteOldItems($model, $itemOk) is made before calling the method $item->save()
As it is I can not let delete all records and then do the insert.
I'm having trouble programming the method deleteOldItems() with a table that has composite primary key. Has anyone done this and can help me, please?
The foreign key field is not supposed to be validate.
You should remove this field from the required field list.
Before saving the students the function setUnsafeAttribute is called, in order to save the foreign key and other eventually values that are not collected from the user.
That's why the function save is called like that: $studentManager->save($model); we pass the main model to the manager for retrive the primary key value (and other eventually needed values)
Suppose the following relationship: a class has many students and a student belongs to a class.
The attribute "id classroom" (fk) in the student model is required and fails validation upon insertion.
How to work around this problem? Open a transaction and validate the student already knowing the id of the classroom?
Please login to leave your comment. | http://www.yiiframework.com/extension/ztabularinputmanager | CC-MAIN-2015-27 | refinedweb | 1,230 | 54.32 |
NAME
Read a single log record from the kernel debuglog.
SYNOPSIS
#include <zircon/syscalls.h> zx_status_t zx_debuglog_read(zx_handle_t handle, uint32_t options, void* buffer, size_t buffer_size);
DESCRIPTION
zx_debuglog_read() attempts to read a single record from the kernel debug
log into the given buffer of size buffer_size bytes.
options must be set to
0.
On success, a single record of type zx_log_record_t is written into buffer. The length of the record in bytes is given in the syscall's return value.
The returned record will have the following format:
typedef struct zx_log_record { uint32_t rollout; uint16_t datalen; uint8_t severity; uint8_t flags; zx_time_t timestamp; uint64_t pid; uint64_t tid; char data[]; } zx_log_record_t;
The fields are defined as follows:
If buffer_size is smaller than the size of the log record, the first buffer_size bytes of the record will be written to the buffer, and the rest discarded. Callers should ensure that their input buffer is at least ZX_LOG_RECORD_MAX bytes to avoid log records from being truncated.
RIGHTS
handle must be of type ZX_OBJ_TYPE_LOG and have ZX_RIGHT_READ.
RETURN VALUE
zx_debuglog_read() returns a non-negative value on success, indicating
the number of bytes written into buffer. On failure, a negative error value
is returned.
ERRORS
ZX_ERR_ACCESS_DENIED handle does not have ZX_RIGHT_READ.
ZX_ERR_BAD_HANDLE handle is not a valid handle.
ZX_ERR_INVALID_ARGS An invalid value to options was given, or buffer was an invalid pointer.
ZX_ERR_SHOULD_WAIT The debuglog contained no records to read.
ZX_ERR_WRONG_TYPE handle is not a debuglog handle.
SEE ALSO
fuchsia.boot.ReadOnlyLog
- [
zx_debuglog_create()]
- [
zx_debuglog_write()] | https://fuchsia.dev/fuchsia-src/reference/syscalls/debuglog_read | CC-MAIN-2021-21 | refinedweb | 246 | 57.98 |
C# to JSON
About
C# to JSON
Convert C# model classes to JSON objects
The rules:
Must supply valid C# code, ideally just classes and structs that expose public properties (methods, statics, and any other application code will be ignored).
If a class references other object types, include those dependency classes or enums too.
If you want your JSON to be populated with sample data, initialize those properties directly (without getters and setters) or create a default constructor and set them there.
Commonly used namespaces (System.Collections.Generic, System.Linq, etc) are automatically included; however, for less commonly used .NET Framework types you may add those namespaces. Example: to use the type
IPAddress
include "
using System.Net;
".
If it doesn't compile in Visual Studio it won't compile here.
See the example below and click the
button to try it out.
Note: This tool is intended to consume reasonably simple C# class hierarchies that have no dependencies on external libraries. Anything too complex may generate errors.
C#
// This will be serialized into a JSON Address object public class Address { public string Street { get; set; } public string City { get; set; } public string State { get; set; } public string PostalCode = "99999"; // initialize properties to generate sample data public Address() { // or set properties in default constructor to generate sample data this.Street = "4627 Sunset Ave"; this.City = "San Diego"; this.State = "CA"; this.PostalCode = "92115"; } } // This will be serialized into a JSON Contact object public class Contact { public int Id { get; set; } public string Name { get; set; } public DateTime? BirthDate { get; set; } public string Phone { get; set; } public Address Address { get; set; } public Contact() { this.Id = 7113; this.Name = "James Norris"; this.BirthDate = new DateTime(1977, 5, 13); this.Phone = "488-555-1212"; this.Address = new Address(); } } // This will be serialized into a JSON array of Contact objects public class ContactsCollection { public ICollection<Contact> Contacts { get; set; } public ContactsCollection() { // initialize array of objects in default constructor to generate sample data this.Contacts = new List<Contact> { new Contact { Id = 7113, Name = "James Norris", BirthDate = new DateTime(1977, 5, 13), Phone = "488-555-1212", Address = new Address { Street = "4627 Sunset Ave", City = "San Diego", State = "CA", PostalCode = "92115" } }, new Contact { Id = 7114, Name = "Mary Lamb", BirthDate = new DateTime(1974, 10, 21), Phone = "337-555-1212", Address = new Address { Street = "1111 Industrial Way", City = "Dallas", State = "TX", PostalCode = "49245" } }, new Contact { Id = 7115, Name = "Robert Shoemaker", BirthDate = new DateTime(1968, 2, 8), Phone ="643-555-1212", Address = null } }; } }
Clear
JSON
Options:
Camel case
Generate comments
Minify | https://csharp2json.io/ | CC-MAIN-2021-31 | refinedweb | 420 | 54.22 |
[EXPL] Xsun (Sparc) Local Exploit (RGB_DB)From: support@securiteam.com
Date: 11/07/02
- Previous message: support@securiteam.com: "[EXPL] QNX Timer Implementation Vulnerable to DoS"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
From: support@securiteam.com To: list@securiteam.com Date: 7 Nov 2002 11:00.
- - - - - - - - -
Xsun (Sparc) Local Exploit (RGB_DB)
------------------------------------------------------------------------
SUMMARY
Xsun is a Solaris server for X version 11. A vulnerability in Sun's
implementation allows attackers to cause it to execute arbitrary code,
allowing them to gain elevated privileges.
DETAILS
Exploit:
/* Xsun(sparc) local exploit
by gloomy (gloomy@root66.org) & eSDee (esdee@netric.org)
------------------------------------------------------------------
Xsun is a Solaris server for X version 11. This program contains
an option that is not really secure nowadays :).
The option is used to determine the color database file. And yeah,
indeed, you guessed it already, it contains a heap overflow.
When we were busy writing this exploit within a multi display
screen, we discovered some weird "unable-to-write-over-stackframe"
problems. We tried everything to just write a few bytes over a
saved program counter, but unfortunatly it was not possible on the
current machine we were using. Then eSDee came up with something
news. In the middle of the night a loud "yippeaaaaaa!" came out
the bedroom of mister Es. He discovered a little section just
below the GOT. It didn't contain \0 bytes and it was writeable.
It's called the ti_jmp_table. I'm sure eSDee will write some
papers about it soon.
Gloomy was busy writing a shellcode that re-opens the STDIN. He
found out that he just could open /dev/tty and then duplicate the
STDERR filedescriptor, so the important descriptors were back
again.
USAGE:
./Xsun-expl [retloc] [ret]
Example:
bash$ gcc -o Xsun-expl Xsun-expl.c -Wall -Werror
bash$ ./Xsun-expl
Couldn't open RGB_DB 'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA.....
...
bash$ id
uid=500(user) gid=0(root)
Greets and kisses:
#netric -
#root66 -
mostlyharmless- [soon]
dB_____ - fijne broer van gloom-ei! :)
squezel - lekker ventje ben jij.
More information available at:
09
[ps. wat een lompe text]
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define PATH"/usr/openwin/bin/Xsun"
#define DISPLAY ":1"
#define SIZE5128
#define RET 0xffbef7bc
#define RETLOC0xfecbea30/* <ti_jmp_table+4> (a pointer to _retu
rn_zero) */
#define DUMMY 0xac1db0ef
struct WORD {
long element;
long dummy;
};
struct TREE {
struct WORDt_s;/* size of this element */
struct WORDt_p;/* parent node */
struct WORDt_l;/* left child */
struct WORDt_r;/* right child */
struct WORDt_n;/* next in link list */
struct WORDt_d;/* dummy to reserve space for self-pointer */
};
char
shellcode[]=
/*
setregid(0,0);setting root permission
s
open("/dev/tty", RD_ONLY);re-open STDIN
dup(2); duplicate STDOUT to STD
ERR
execve("/bin//sh", &argv[0], NULL); start the shell
exit(); exit
*/
"\x90\x1d\x80\x16"// xor%l6, %l6, %o0
"\x92\x1d\x80\x16"// xor%l6, %l6, %o1
"\x82\x18\x40\x01"// xor%g1, %g1, %g1
"\x82\x10\x20\xcb"// mov0x2e, %g1
"\x91\xd0\x20\x08"// ta 8 [setreg
id(0,0)]
"\x21\x0b\xd9\x19"// sethi%hi(0x2f646400), %l0
"\xa0\x14\x21\x76"// or %l0, 0x176, %l0
"\x23\x0b\xdd\x1d"// sethi%hi(0x2f747400), %l1
"\xa2\x14\x60\x79"// or %l1, 0x79, %l1
"\xe0\x3b\xbf\xf8"// std%l0, [ %sp - 0x8 ]
"\x90\x23\xa0\x08"// sub%sp, 8, %o0
"\x92\x1b\x80\x0e"// xor%sp, %sp, %o1
"\x82\x10\x20\x05"// mov0x05, %g1
"\x91\xd0\x20\x08"// ta 8 [open("
/dev/tty",RD_ONLY)]
"\x90\x10\x20\x02"// mov0x02, %o0
"\x82\x10\x20\x29"// mov0x29, %g1
"\x91\xd0\x20\x08"// ta 8 [dup(2)
]
"\x21\x0b\xd8\x9a"// sethi%hi(0x2f626800), %l0
"\xa0\x14\x21\x6e"// or %l0, 0x16e, %l0
"\x23\x0b\xcb\xdc"// sethi%hi(0x2f2f7000), %l1
"\xa2\x14\x63\x68"// or %l1, 0x368, %l1
"\xe0\x3b\xbf\xf0"// std%l0, [ %sp - 0x10 ]
"\xc0\x23\xbf\xf8"// clr[ %sp - 0x8 ]
"\x90\x23\xa0\x10"// sub%sp, 0x10, %o0
"\xc0\x23\xbf\xec"// clr[ %sp - 0x14 ]
"\xd0\x23\xbf\xe8"// st %o0, [ %sp - 0x18 ]
"\x92\x23\xa0\x18"// sub%sp, 0x18, %o1
"\x94\x22\x80\x0a"// sub%o2, %o2, %o2
"\x82\x18\x40\x01"// xor%g1, %g1, %g1
"\x82\x10\x20\x3b"// mov0x3b, %g1
"\x91\xd0\x20\x08"// ta 8 [execve
("/bin/sh","/bin/sh",NULL)]
"\x82\x10\x20\x01"// mov0x01, %g1
"\x91\xd0\x20\x08"// ta 8 [exit(?
)]
"\x10\xbf\xff\xdf"// bshellcode
"\x90\x1d\x80\x16"; // or %o1, %o1, %o1
int
main(int argc, char *argv[])
{
struct TREE faketree; // our friendly little
tree
char buffer[SIZE+sizeof(faketree)+1];
unsigned int ret= RET;
unsigned int retloc = RETLOC;
unsigned int dummy= DUMMY;
if (argc > 1) retloc= strtoul(argv[1], &argv[1], 16);
if (argc > 2) ret = strtoul(argv[2], &argv[2], 16);
faketree.t_s.element = 0xfffffff0;
faketree.t_s.dummy = dummy;
faketree.t_n.element = retloc - 8;
faketree.t_n.dummy = dummy;
faketree.t_l.element = 0xffffffff;
faketree.t_l.dummy = dummy;
faketree.t_r.element = dummy;
faketree.t_r.dummy = dummy;
faketree.t_p.element = ret;
faketree.t_p.dummy = dummy;
faketree.t_d.element = dummy;
faketree.t_d.dummy = dummy;
memset(buffer, 0x41, sizeof(buffer));
memcpy(buffer + 3999 - (strlen(shellcode) - 8), shellcode,
strlen(shell
code));
memcpy(buffer + SIZE, &faketree, sizeof(faketree));
buffer[SIZE + sizeof(faketree)] = 0x0;
fprintf(stdout, "Retloc = 0x%08x\n"
"Ret= 0x%08x\n",
retloc, ret);
execl(PATH, "Xsun", "-co", buffer, DISPLAY, NULL);
return 0;
}
/* [eof] */
ADDITIONAL INFORMATION
The information has been provided by <mailto:gloomy@root66.org> gloomy
and <mailto:esdee@netric.org> eSD] QNX Timer Implementation Vulnerable to DoS"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ] | http://www.derkeiler.com/Mailing-Lists/Securiteam/2002-11/0019.html | CC-MAIN-2015-27 | refinedweb | 903 | 57.87 |
When I run:
curl -D - -X POST -u myuuid:mypass -d '{"access":"private","users":[{"uid":"myuuid","permission":"AdminReadWrite"}]}' \ ''
I get this error:
{"error":"corpus does not exist","url":"/myuuid/corpname"}
Any ideas?
(X-Global-Transaction-ID: 82095273)
Answer by mfrager (76) | Feb 06, 2015 at 01:34 AM
Nevermind...
There's a typo in the docs. I changed "POST" to "PUT" and it worked!
Awesome!
you should mark your own answer as accepted :-P
Answer by Allen.Dean (939) | Feb 06, 2015 at 08:06 AM
Thanks for finding the error. We'll change that example.
Answer by Luis A. Lastras (761) | Feb 06, 2015 at 08:00 PM
@mfrager, have you had success adding documents to a corpus in Concepts Insights? Typically you will want the documents to have enough text so that at least 10 concepts from Wikipedia are successfully detected by Concept Insights. Also in our experience it starts to show useful behavior when the number of documents added is in the hundreds or a few thousands.
Answer by mfrager (76) | Feb 17, 2015 at 01:02 PM
I was able to upload my corpus. I'm pretty happy with how it all turned out and I plan on continuing to work with the Concept Insights API, I think it has great potential.
If you'd like to take a look at the project I'm working on here's some details. This is all in alpha development of course...
I've loaded up the entire congressional record from 2014 and linked it to a page for each representative. Then I'm using the Concept Insights API to do a topic-based search on the record transcripts.
Here's the link:
A few tips, you'll need to select "Congress Records" from the search, and then enter a partial topic and then click on the topic you want from the drop-down menu to search before pressing return (otherwise it won't work).
For an example try doing a search for "Immigration" or try this link for a short cut:⊤ic=Immigration
Once you search you'll get a list of the congressional transcripts that contain a discussion related to the topic, the members who participated in those discussion, and a list of related topics.
Your use case seems extremely interesting, is it still online ? I can't access the website
Answer by Luis A. Lastras (761) | Feb 18, 2015 at 02:21 PM
Awesome, we tried it out. It's good, it feels that it has a clear use case.
Quick suggestion. When you do a semanticSearch, you also get back a list of concepts with the coordinates within which they appear in each of the documents. There is a "score" field that tells you how relevant the concept (within the document) is to the query. You could use this data in order to do some highlighting of the documents when you click them.
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Can I use Concept Insights API for Q&A ? 4 Answers | https://developer.ibm.com/answers/questions/174049/how-do-i-create-a-new-corpus-for-concept-insights.html?sort=votes | CC-MAIN-2019-47 | refinedweb | 546 | 71.24 |
c++ compiler could compile code like this, and it executed correctly
#include <stdio.h>
int main() {
printf("test...\n");
return 0;
}
Nobody can give you a definitive answer without knowing what implementation you're using.
Cheers and hth. - Alf gave one possibility, which is that the
stdio.h that is included by a C++ program may not be the same as the
stdio.h that is included by a C program. Another possibility is that it is the same header, and there is an
extern "C" block, and you just can't see it. For example, I use gcc, and my
/usr/include/stdio.h contains a
__BEGIN_DECLS macro, which expands to
extern "C" { when compiled as C++. See Do I need an extern "C" block to include standard C headers? | https://codedump.io/share/oDWMKTJVC1ZN/1/why-could-c-include-ltstdiohgt-and-invoke-printf-method-which-is-cplatformubuntu-1404-compilergcc-484 | CC-MAIN-2017-17 | refinedweb | 131 | 68.77 |
.
The algorithmThe algorithm I use is a bog-standard recursive walk of the cells in the maze. We start with walls between all the cells, and pick a random cell. Then take each of it's four neighbors in random order. If a neighbor has been visited, we skip it. Otherwise, remove the wall between those two cells, and recursively walk from that neighbor as well.
You can find this algorithm described on rosettacode. This will include implementations in a number of languages, including a more idiomatic Haskell version.
RepresentationA maze is just an array of cells that either have halls or walls between each cell. Each cell needs two walls, one for each direction, and boolean to note that it's been visited. Which gives us the basic data types for a maze:
data Wall = Wall | Hall deriving Eq data Cell = Cell { x, y :: Wall, visited :: Bool } type Board = Array (Int, Int) Cell
xwall is the wall that runs in the
ydirection with the largest
xcoordinate, and vice versa.
To work with the array, we need a few tools from
Data.Array
Data.Array:
import Data.Array (Array, array, bounds, (//), (!))
Arraytype for our type declarations, which we've already seen. The
arrayfunction is used to create the initial array.
boundsgets the bounds of the array so we don't have to pass those around.
//is used to create a new array with a list of changes to an array, and
!is used to reference a
Cellin the array.
Generating the boardSo our initial maze needs to have every cell with both walls, and initially not visited. That's just a
Cell wall wall false.
But our maze is going to have a border around it, for a number of reasons. We can make the walk easier by creating border cells as visited. So the walk won't need to do bounds checking. And the border on the low coordinate sides will have the wall on that side, and no others. That will simplify drawing the maze. And as a final touch, we'll put entry and exit doors in the maze at the diagonally opposite corners on the axis.
So we have a function
makeCellthat looks convoluted, but each part is straightforward. For a
Boardof width
wand height
h, we make the cell at
i, jwith:
makeCell i j = Cell (if j == 0 then Hall else Wall) (if i == 0 || i == 1 && j == h || i == w && j == 0 then Hall else Wall) $ i == 0 || i > w || j == 0 || j > h
Cellwith an
x
Wallexcept for the first element in the
jdirection, and a
yWall except for the first element in the
idirection, as otherwise we'd try and draw those. We also create
Hall's for
1, hand
w, 0, which will be the entry and exit for the maze.
Finally, if either
xor
yis 0 or
xis greater than
wor
ygreater than
h, then mark these border
Cell's as
Visited, so we won't visit them during the walk. All other cells haven't been visited yet.
So now we can create the array with
arrayand
makeCell:
makeBoard w h = array ((0, 0), (w+1, h+1)) [((i, j), makeCell i j) | i <- [0..w+1], j <- [0..h+1]]
arraytakes list of pairs of indices and values and converts it to an array whose bounds are given as the first argument. In this case, bounds are
(0, 0)and
(w+1, h+1). That makes the border the indices that have 0 for either
xor
y, and
w+1for
xand
h+1for
y. A list comprehension generates the indices, and we call
makeCellon them to create the
Cellfor each index.
The walkWe start with helper functions to remove each wall from a cell. Well, since this is a functional language, we can't actually remove the wall, so instead well have functions that return a cell with the appropriate wall removed. And one to return a visited cell.
clearY, clearX, visit :: Cell -> Cell clearY cell = cell {y = Hall} clearX cell = cell {x = Hall} visit cell = cell {visited = True}
xand
ydirections, so we'll want a list of all possible steps,
allSteps:
allSteps = [(0, 1), (0, -1), (1, 0), (-1, 0)]
walkMazefunction is straightforward. Just pick a random cell in the maze, then call the internal helper
walkCellfor
allSteps, that board position and our original
Board:
i <- state $ randomR (1, (fst . snd $ bounds origBoard) - 1) j <- state $ randomR (1, (snd . snd $ bounds origBoard) - 1) walkCell (i, j) allSteps origBoard
walkCellimplements the "in every direction from each cell" part of the algorithm by calling itself recursively, removing a random move from the list of moves it was passed on each recursion, stopping when there are no more moves. It uses
doStepto walk the
Boardafter that step:
walkCell _ [] b = return b walkCell start steps board = do step <- (steps !!) <$> (state . randomR) (0, length steps - 1) walkCell start (delete step steps) =<< doStep start step (board // [(start, visit $ board ! start)])
doStepjust calls
walkCellon
allStepsand the cell it steps to, after removing the wall between the
Cellit's stepping
fromand the new
Celll. The last bit is the hard part, requiring examining the move in detail:
walkMaze :: Board -> State StdGen Board walkMaze origBoard = let clearY cell = cell {y = Hall} clearX cell = cell {x = Hall} visit cell = cell {visited = True} allSteps = [(0, 1), (0, -1), (1, 0), (-1, 0)] walkCell _ [] b = return b walkCell start steps board = do step <- (steps !!) <$> (state . randomR) (0, length steps - 1) walkCell start (delete step steps) =<< doStep start step (board // [(start, visit $ board ! start)]) in do i <- state $ randomR (1, (fst . snd $ bounds origBoard) - 1) j <- state $ randomR (1, (snd . snd $ bounds origBoard) - 1) walkCell (i, j) allSteps origBoard
Boardfor the various recursive calls, rather than mutating a
Boardand just using recursion to keep track of the progress of the walk.
This is liable to create a lot of extra state in each recursion. I haven't made any attempts to minimize that, which you would want to do in a solution for production use. Idiomatic Haskell would use the State monad for the
Boardto hide the extra plumbing, as is done with the random number generator.
Displaying the boardWhile the walk above is the meat of this blog entry, I find the display code interesting, so will cover that as well.
It would be nice to be able to plug in various different types of output to display the maze, so that we can debug with ASCII to a terminal or a Diagram before adding code to generate OpenSCAD code. So we'll use a
Boarddrawing function that takes functions that generate the walls and pastes them together. The type for the function is:
drawBoard :: (Board -> Int -> Int -> a) -- make X-direction cell walls -> (Board -> Int -> Int -> a) -- make Y-direction cell walls -> ([a] -> b) -- combine [walls] into a row -> ([b] -> IO ()) -- Draw the board from [rows] -> Board -- Board to draw -> IO ()
Wall's, one in each direction. Then a function to combine a list of walls into a row, and finally one that takes a list of rows and outputs the final maze. For a larger program, it might be worthwhile to use a
Renderdata type to hold those for functions, but for a simple demo, it's just extra formula.
The wall drawing functions get the
Boardand indices, as the indices may be needed to calculate where the wall needs to go. However, we are also going to generate the rows by generating the walls for the
Cell's in order of increasing
x, then do the same to put the rows together in order of increasing
y.
So the actual
drawBoardcode is:
drawBoard makeX makeY makeRow makeMaze board = makeMaze . concat $ [firstWall]:[drawCells j | j <- [1 .. height]] where height = (snd . snd $ bounds board) - 1 width = (fst . snd $ bounds board) - 1 firstWall = makeRow [makeX board i 0 | i <- [0 .. width]] drawCells j = [makeRow [makeY board i j | i <- [0 .. width]], makeRow [makeX board i j | i <- [0 .. width]]]
firstWall, which is the
xdirection walls for the 0'th
yrow. We don't bother making the
ydirection walls for that row, since they aren't part of the maze proper. That
firstWallis wrapped in a list and consed onto the list output by
drawCells, which outputs a list consisting of a row
xwalls and a row of the
ywalls for the
Cell's in that
ydirection. We draw the 0
Cells in each row to generate the
ydirection
Wallthat forms the boundary of the maze. There are no
xdirection
Walls in those
Cells, but either
makeRowor
DrawXwill be responsible for dealing with any other artifacts that these cells might generate.
That result is passed to
concatto turn it into a list of rows instead of a list of lists of rows, which are passed to
makeMazeto output the maze.
Drawing in ASCIIFor ASCII output, we only need two extra functions:
charX, charY :: Board -> Int -> Int -> String charX board i j = if y (board ! (i, j)) == Wall then "---+" else " +" charY board i j = if x (board ! (i, j)) == Wall then " |" else " "
x
Wallis a horizontal line of dashes, and a
ywall is a vertical bar.
Hall's are just blank spaces, except for a
+at an intersection. Note that an
x
Wallis the
yelement of a
Cell, as the
Cellelement is named for the direction you are facing, but the
Wallrendering is named for the direction the wall runs.
makeRowis simply
drop 3 . concat, to paste the strings together and then remove the extra
Hall's
drawCellscreates for the 0 cells in each row.
makeMazeis just
putStr. unlines.
At this point, if you load the module (available via the fossil repository link on the right) into ghci, you can print square grids. Just use
:main 16 8to print a 16 by 8 maze. Or on a Unix system, you should be able to do
./maze.hs 16 8to generate a maze from the shell.
Graphical outputThat works, but it's not very pretty. So let's do a little graphics. Since I'm not much of a graphics designer, it still won't be very pretty.
Support routinesThis is a bit more complicated, so let's start with a couple of support routines.
diaSpaceis used to create a spacer. It takes an
R2, which is a direction, and a
Doubleindicating how long it is. It outputs a
Diagram B R2, which is something we can draw. Given that it's a spacer, it won't draw anything when drawn.
diaSpace :: R2 -> Double -> Diagram B R2 diaSpace unit size = phantom (fromOffsets [unit # scale size] :: Diagram B R2)
diaCelldoes all the work. It needs to know which
Wallto check in a
Cell, which direction to draw in, any spacer needed, and the cell size. Plus the board and the cell's index:
diaCell :: (Cell -> Wall) -> R2 -> Diagram B R2 -> Double -> Board -> Int -> Int -> Diagram B R2 diaCell side unit space cellSize board i j = space ||| make (side (board ! (i, j))) where make Wall = strokeT (fromOffsets [unit # scale cellSize]) make Hall = diaSpace unit cellSize
diaCellreturns the space in front of the result of calling the internal function
makeon the
Cells'
Wall.
makeis simple - it uses
diaSpaceto return a blank space for a
Hall, and the
Diagramprimitives to create a line of length
cellSizein the given direction.
Drawing cells.Given
diaCell, the two routines for drawing walls are simple:
diaX, diaY :: Double -> Board -> Int -> Int -> Diagram B R2 diaX = diaCell y unitX mempty diaY cellSize = diaCell x unitY (diaSpace unitX cellSize) cellSize
diaXand
diaYmatch the types needed by
drawBoard.
diaXis just
diaCellwith the
y
Wallselector as it's first argument, the
xdirection and an empty spacer, as the wall spans the entire length of the
Cell.
diaYneeds the
cellSizeargument as well, since the spacer it passes to
diaCellis a
cellSizespacer created by
diaSpace.
Drawing the boardThe row creator for
drawBoardis simply the
Diagramfunction
hcat, which accepts a list of diagrams and puts them together horizontally in a new diagram.
The board creator is almost that simply, but is actually long enough to get it's own function:
diaBoard :: Double -> [Diagram B R2] -> IO () diaBoard ww rows = renderCairo "maze.png" Absolute $ vcat rows # centerXY # pad 1.1 # lwO ww
Diagramfunction
vcat, which stacks the diagrams up vertically instead of horizontally. That image is then centered by
centerXY, padded by
pad 1.1, and the line weight is set to the wall width with
lw0 ww. That diagram is passed to
renderCairoalong with some extra arguments so that it creates an appropriately scaled output in the file
maze.png.
Seeing the resultThe version of
maze.hsin the fossil repository has the Diagram (and OpenSCAD) drawing code commented out. Once you install the
diagramspackage and the
diagrams-cairopackage, you can change that. Look for three places where a line starts with
{- Comment out. The first two will need to be moved down to the next blank line. The last one will need to be moved down to beneath
diaBoard. You can now run this in
ghcias
:main 16 8 40 2, or as
./maze.hs 16 8 40 2. The two new arguments are the size of the cell and the width of the walls to draw. The old ASCII invocations will still work as well.
After running it with 4 arguments, the file
maze.pngwill be created in the current directory, and you can display that.
Expanding this to display images from the command line, or to embed it in an app for solving mazes, is left as an exercise for the reader. In which case, it ought to be made pretty as well.
Printing in 3dThe inspiration was a 3d-printed maze, so let's do that. This is very similar to the Diagrams code, so the commentary will be a bit shorter.
To show what using an encapsulating data type would look like, this uses the
SCADCelldata type, consisting of the side selector, a routine to construct the appropriate wall, and a
Vector3dto move the wall to the appropriate place in the cell:
data SCADCell = SCADCell (Cell->Wall) -- Wall extractor (Double -> Double -> Double -> Model3d) -- Wall drawing Vector3d -- translation
scadCell.
scadCelljust creates a the appropriate wall and base, or a 0-sized block if this is a border
Cell. It also need the cell size, wall dimensions and base depth to create those models.
scadXand
scadYjust call
scadCellwith the appropriate
SCADCell.
scadX, scadY :: Double -> Double -> Double -> Double -> Board -> Int -> Int -> Model3d scadX cs = scadCell (SCADCell y (flip box) (0, cs, 0)) cs scadY cs = scadCell (SCADCell x box (cs, 0, 0)) cs scadCell :: SCADCell -> Double -> Double -> Double -> Double -> Board -> Int -> Int -> Model3d scadCell (SCADCell side box' move) cs ww wh bd board i j = make (side $ board ! (i, j)) # translate (cs * fromIntegral (i - 1), cs * fromIntegral (j - 1), 0) where make Wall = box' ww (cs + ww) (bd + wh) # translate move <> base make Hall = base base = if i == 0 || j == 0 then box 0 0 0 else box (cs + ww) (cs + ww) bd
unionfor this. That same function also serves to join the rows into a board, so we just need to compose it with
drawin order to print the maze. However, this prints the maze "upside down" compared to the previous two rendering engines, so we use
mirrorto fix that as well. No real need, but it feels like the right thing.
You'll need to install version 0.2.1.1 or later of my Haskell OpenSCAD library from hackage and uncomment the appropriate code segments to use it. You can then run it as either
:mainor
./main.hs, using arguments like 16 8 20 2 4 10. That's the same four arguments as the Diagram version, with the depth of the base and the height of the walls added.
To see the results, you'll also need the OpenSCAD application. That can generate an STL file, and getting it to a 3d printer from there is up to you.
MainJust for completeness, a brief look at the main routine that ties it together. This is really just a kludge to test the others, but it does the job.
The outline is to get the arguments, map them to integers. Sorry, no fractional sizes here. Then convert those to floats for the things that need them. Switch on the length of the argument list to either raise a usage error or create a
drawBoard'function that's just the
drawBoardinvoked with the functions appropriate to the type of output we want.
Then get a random number generator, and run
mazeWalkusing it on a board of the appropriate size, which we will use the newly created
drawBoard'to output.
main :: IO () main = do args <- map read <$> getArgs let floats = map fromIntegral args drawBoard' = case length args of 2 -> drawBoard charX charY (drop 3 . concat) (putStr . unlines) 4 -> drawBoard (diaX cs) (diaY cs) hcat (diaBoard ww) where [_, _, cs, ww] = floats 6 -> drawBoard (scadX cs ww wh bd) (scadY cs ww wh bd) union (draw . mirror (0, 1, 0) . union) where ([_, _, cs, ww, bd, wh]) = floats {- Comment out drawing argument handling -} _ -> error "Width Height [CellSize WallWidth | CellSize WallWidth WallHeight BaseDepth]" gen <- newStdGen drawBoard' $ evalState (walkMaze $ makeBoard (head args) (args !! 1)) gen | http://blog.mired.org/2015/04/functional-mazes.html | CC-MAIN-2018-09 | refinedweb | 2,873 | 70.02 |
A Cullen Number is a number of the form is 2n * n + 1 where n is an integer. The first few Cullen numbers are 1, 3, 9, 25, 65, 161, 385, 897, 2049, 4609 . . . . . .
Examples:
Input : n = 4 Output :65 Input : n = 0 Output : 1 Input : n = 6 Output : 161
Below is C++ implementation of formula. We use bitwise left-shift operator to find 2n, then multiply the result with n and finally returns (1 << n)*n + 1.
// C++ program to find Cullen number #include<bits/stdc++.h> using namespace std; // function to find n'th cullen number unsigned findCullen(unsigned n) { return (1 << n) * n + 1; } // Driver code int main() { int n = 2; cout << findCullen(n); return 0; }
Output:
9
Properties of Cullen Numbers:
- Most of the Cullen Numbers are composite numbers.
- n’th Cullen number is divisible by p = 2n – 1 if p is a prime number of the form 8k – 3.
Reference:. | https://www.geeksforgeeks.org/program-find-cullen-number/ | CC-MAIN-2018-09 | refinedweb | 155 | 67.18 |
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