Subset (2)

default · 235k rows

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train · 223k rows

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
My First GreaseMonkey Script For Full As A Goog I just authored my first every GreaseMonkey script. In the past I complained about the fact that Full As A Goog opens up links in the same window. To remedy this, I have created a GreaseMonkey script that grabs all the feed links and sets the TARGET attribute of their links to be "_blank". And just like that, the links work perfectly. I have never done a GreaseMonkey script before and I have to say, it was really easy and fun. This might be something that I start doing for any site that bugs me. Here is the simple script: - // ==UserScript== - // @name Full As A Goog - Blank Window - // @namespace - // @description This forces the RSS links in fullasagoog.com to open up in a new window. - // @include* - // @include* - // ==/UserScript== - // Get all of the links in the page. - var arrLinks = document.getElementsByTagName( "a" ); - // Loo over the links so we can check the value for the url. - // We only care about links that are being routed through - // "go.cfm" but we have to get all of them from the DOM first. - for (var i = 0 ; i < arrLinks.length ; i++){ - // Check to see if the link is one that redirects to an - // RSS feed blog entry. - if ( - arrLinks[ i ].getAttribute( "href" ) && - (arrLinks[ i ].getAttribute( "href" ).indexOf( "go.cfm" ) >= 0) - ){ - // This is a link that points to a site. Set the target - // to open up in a new window. - arrLinks[ i ].setAttribute( "target", "_blank" ); - } - }	http://www.bennadel.com/blog/349-my-first-greasemonkey-script-for-full-as-a-goog.htm	CC-MAIN-2016-07	refinedweb	248	84.47
Mobile Corner Set up and use create a simple Windows Phone program that connects to Azure Mobile Services. Recently, Microsoft announced the Windows Azure Mobile Services (WAMS), a set of cloud services designed to jump start mobile application development. Currently, all that's shipped is an SDK for Windows 8 application development. However, as the service is exposed via an Odata-like feed, it's possible to get started using these services in your Windows Phone applications today. This article will show how to set up and get started with your first WAMS, before jumping into accessing it from an application. A Windows Azure Mobile Service accelerates a normal mobile application development cycle by providing some of the backend services that most applications require. Currently, these are focused around data storage and push notifications. Data storage is provided via a SQL Azure database, which is exposed to the mobile applications via a REST API. The push notifications are currently limited to Windows 8, and as such won't be covered in this article. The first thing you'll need is a Windows Azure account with the Mobile Services preview feature enabled. Microsoft's provided a quick tutorial that will step you through the process of creaing a Windows Azure account and enabling preview features (in step 3, three make sure you select the Mobile Services feature to try it out). The next step is to set up a mobile service to work with. Open and sign into the Windows Azure management portal, then select the Mobile Services tab from the left menu to view the list of Mobile Services (shown in Figure 1). From the action bar at the bottom of the screen click the New button, followed by the Create button, to begin creating a new Mobile Service. The New Mobile Service wizard will step you through specifying a URL (think of this as the name of your service) and the details of the SQL Azure database you're going to use. In this case we're going to specify a new database sitting on a new database server. If you have existing SQL Azure databases you may decide to use one of those, or reuse an existing database server. After you've entered all the information and hit the Complete (tick) button, the management portal will take a couple of minutes to finish setting up your service. Once your service is ready to go, it will appear in the Mobile Services area with a status of Ready. Click on your new mobile service to start interacting with it. On the welcome page for your new mobile service, you'll see a number of steps to help you start building a Windows 8 application against this service. These steps include a couple of important pieces of information needed to access your mobile service from a Windows Phone application. Click the "Connect an existing Windows Store app" link to expand out the instructions. From Step 2, record both the URL and application key from the example code displayed (as illustrated by the comments): public static MobileServiceClient MobileService = new MobileServiceClient( "", // This is the URL for your mobile service "QEoycHPhsULrrqnrHBVKydvlPugspY77" // This is the application Key ); In this example, we're going to have a single table which records a list of articles written for the this column. Each article will have two properties: a title and the URL of the article itself. From the top of the management portal for your new mobile service, select the Data tab, and then click the Add a Table button in the middle of the screen (or hit the Create button from the action bar). Give the table a name, Article, and hit the Complete button. There are other options you can tweak to adjust permissions for the table, but for the purposes of this example we'll go with the default values. You'll notice that the newly-created table appears in the Data tab, and that if you click through to the table, then select the Columns tab, it consists of a single column, id. There is currently no way to add columns via the management portal. Initially, all mobile services are setup with the Dynamic Schema option enabled. This means that the schema will update to automatically accommodate additional properties dynamically. Of course, you'll probably want to disable this option before you make your application widely available to prevent abuse. Let's flip over to Visual Studio and create a new Windows Phone application, which we'll use to add and view the list of articles. The interface will be relatively straight forward, consisting of two TextBlocks, two TextBoxes and a Button. <StackPanel x: <TextBlock Text="Title" /> <TextBox x: <TextBlock Text="Url" /> <TextBox x: <Button Content="Submit" Click="SubmitClick" /> </StackPanel> We'll start with the code for the SubmitClick method and the Article class, which we'll use to send and receive data with the mobile service (note we're accessing the XAML elements directly to keep the example simple; in production, you'd want to use model-view/view-model (MVVM) and data binding to separate the view from the logic of your application). In this code, we're using asynchronous programming to make the code more readable. public class Article { public int? Id { get; set; } public string Title { get; set; } public string Url { get; set; } } private async void SubmitClick(object sender, RoutedEventArgs e) { var article = new Article {Title = TB_Title.Text, Url = TB_Url.Text}; article = await Insert(article); MessageBox.Show("Article inserted: " + article.Id); } The code in the Insert method (Listing 1) is where all the heavy lifting happens, via communication with the mobile service. Essentialy, the Article object is serialized to JSON to be sent to the mobile service via a POST operation. Note that because we don't want the id property to be sent when inserting a new object, we've used Json.net rather than the built-in DataContractJsonSerializer (it's also significantly quicker). If you now check back in the management portal, you'll see that a record has been added to the Article table, and both Title and URL columns have been added. The code in Listing 2 illustrates how you can read the articles from the mobile service. It uses a GET operation to retrieve articles. To do an update, use the PATCH verb, and the DELETE verb to delete an item (both these require you to add "/<id>" to the end of the URL, where <id> is the id of the item you wish to update or delete). In this article you've seen an example of how you can setup and start calling a Windows Azure Mobile Service from within your Windows Phone application. This information was put together based on an analysis of the Windows 8 client library, and by monitoring the calls to the mobile service using Fiddler.	https://visualstudiomagazine.com/Articles/2012/09/24/win-azure-mobile.aspx?Page=1	CC-MAIN-2016-22	refinedweb	1,148	58.32
Created on 2012-05-25 10:59 by jens.jaehrig, last changed 2015-02-13 23:41 by berker.peksag. This issue is now closed. argparse uses per default abbreviation in unambiguous cases. I don't want abbreviation and i'd like to disable it. But theres no option to do this. Only to override the Handler like suggested here: ################ # Example # ################ import argparse parser = argparse.ArgumentParser() parser.add_argument('--send', action='store_true') parser.parse_args(['--se']) # returns Namespace(send=True) But i want it only to be true when the full parameter is supplied. To prevent user errors. I am dubious as to the use of this: I think resolving partial args is one of the best thing since invented since sliced bread. However, it's a good project to get my feet wet, so I'll take it on. I should have a patch later today--I'm working on test-cases just now. I created a patch that exibhts the requested behavior. I added tests, and updated the documentation. I ran the test-suite against a build of Python 3.3.0a3+, and all tests check out. This changes the public API of argparse.ArgumentParser and of its parse_args() method. I think it makes a lot of sense to allow people to disable abbreviations, so +1 on the feature request. The patch looked good. There was one typo - using "accept_abbrev" in the docstring instead of "allow_abbrev" as in the implementation, and I fixed that and uploaded a new patch. To be complete, the patch also needs to add some documentation, edit Misc/NEWS, etc. See: Sorry, my mistake, the doc changes were already in the patch. I just checked them and they look good too. So everything's ready to commit. Thanks for your contribution! Jonathan: we are in feature freeze right now preparing 3.3 for release, so you might want to ping the issue once 3.3 is out to remind us to do the checkin. Ping :) For a programmer who needs to turn off this abbreviation matching now, a simple solution is to subclass ArgumentParser: class MyParser(ArgumentParser): def _get_option_tuples(self, option_string): return [] This could be the place to implement more specialized matching (e.g. do not match on strings like '--sync'). Update the patch - test_argparse.py - cleanup spaces argparse.rst - merging conflicts Update the patch - issue_14910_3.diff argparse.rst - merging conflicts Daniel, I left some comments in Rietveld. Also it doesn't seem that you addressed the previously left comments when you fixed up the patch. Oh, completely missed comments there too! I hope I got them all in a good way! Sorry for a new patch this close, but just tripple checked the documentation and noticed a word to much. Made it more clear hopefully No worries, Daniel. You should have received an email when comments were posted to the review, did you? If you you may want to check your settings in the bug tracker. I left a couple of additional comments on the documentation file, but other than that this LGTM. Eli, will look into those tomorrow morning, so a final patch will come during tomorrow. Checked my spam folder - and there they where, fixed the settings now so I get it faster. Fixed documentation issues Updated patch Ezio, could you see if your comments were addressed? Steven, do you want to take another look, or is this OK to commit? This breaks custom actions. e.g.: class dict_action(argparse.Action): def __init__(self, a, k): argparse.Action.__init__(self, a, **k) TypeError: __init__() got an unexpected keyword argument 'allow_abbrev' Ignore previous comment, I wish I could delete it. I simply provided the allow_abbrev to the wrong function and spent zero time investigating the error. It looks like the previous comments were addressed in the latest patch. Is this still planned for 3.5? Alpha 1 is next week according to PEP478. The patch LGTM. In Doc/library/argparse.rst: - add_help=True) + allow_abbrev=True, add_help=True) should be add_help=True, allow_abbrev=True) I'll add a release note and commit it. Thanks! New changeset 99302634d756 by Berker Peksag in branch 'default': Issue #14910: Add allow_abbrev parameter to argparse.ArgumentParser. Committed. Thank you all for patches and reviews :)	https://bugs.python.org/issue14910	CC-MAIN-2018-26	refinedweb	704	68.77
Include external library - xingelxangel Hello together, I'm very new to the whole QT area. At this point I'm using an ubuntu and I installed the QT creator. For my work I have to develop a project which is using CUDD (). So I downloaded CUDD and made a "make" command to build it. After that I tried to add the libs to the QT creator. I added a new SubProject and then a new C++ project. Then I tried to implement a simple example. I added the libs with the help of the gui and the "Add external lib" stuff of the QT creator. My ".pro" file contains the path extensions, the lib extensiona and so on. (see "compliling and linking under) Then I had a lot of problems: - I was not able to use: #include "util.h" #include "cudd.h" I had to provide the whole path here (/home/...... etc.). What am I doing wrong here? - I tried to initiate this CUDD stuff from within my test code and I was told: "undefined reference to ....." What am I doing wrong here? I can go into the cudd code by typing F4 but it wouldn't build my test project. Can you please help me? Thanks in advance. Best regards, Eric - SGaist Lifetime Qt Champion Hi and welcome to devnet, Can you post your pro file ? Did you also add @DEPENDPATH += Path/To/CUDD/includes@ To your pro file ? - Salvatello undefined reference to imp_zn5……….Ev Your mistake is this?	https://forum.qt.io/topic/48766/include-external-library	CC-MAIN-2017-34	refinedweb	250	85.69
I2C Get Byte, Print over UARTvkaiser_1860311 Nov 8, 2016 1:19 PM Hello, I seem to be having some trouble setting up I2C, and/or formatting the data to view it over the UART. I'm hoping someone can please identify my error(s) and help me to correct them. I am using the PSoC4 Pioneer kit. I have connected to the SCL/SDA the corresponding pins of an MCP9808 breakout board (and +5V/GND). MCP9808 I2C Address: 0x18 MCP9808 Temperature Register: 0x05 (2 Byte data output) I have confirmed with a different MCU/FW setup that the MCP9808 is working correctly over I2C. The output I2C data out (Address and Register seem to be sending correctly) I see on the scope is not data I would expect - which leads me to believe that my I2C protocol is incorrect. The scope data is also not what I'm seeing reported in TeraTerm - so I may have data formatting issues too. I am seeing my UART test reported in TeraTerm, so that seems to be fine. Any guidance would be greatly appreciated! Thank you. #include <MCP9808.h> #include <stdio.h> #define MCP_I2C_ADDRESS 0x18 #define MCP_REGISTER 0x05 uint32 MCP_temp[2]; void Get_Temp(void); int main() { /* Initialization of Variables / char OutputString[2]; / Initialization / Startup / I2C_Start(); UART_Start(); / Enabling the Global Interrupt / CyGlobalIntEnable; / Application code / UART_UartPutString("\r\nGet Temp: CONNECTED \r\n"); //Check UART/Terminal connection for(;;) { / Call the function to get the current temp via I2C / Get_Temp(); / Store formatted data as string / sprintf(OutputString, "%lu", MCP_temp); / Print the received temp to Hyperterminal / UART_UartPutString(OutputString); UART_UartPutString("\r\n"); CyDelay(1000); } } / END MAIN() / /****************************************************************************** * Function Name : Get_Temp ******************************************************************************** * Summary: * It receives the current temp from the MCP9808 in the Current_temp array. * * Parameters: * None * * Return Value: * None ******************************************************************************/ void Get_Temp(void) { //Initialize Transaction for Writing I2C_I2CMasterSendStart(MCP_I2C_ADDRESS, I2C_I2C_WRITE_XFER_MODE); //Indicate Register to Write to I2C_I2CMasterWriteByte(MCP_REGISTER); I2C_I2CMasterSendRestart(MCP_I2C_ADDRESS, I2C_I2C_READ_XFER_MODE); //Read from Register (2 Bytes, last byte NAKed) MCP_temp[0] = I2C_I2CMasterReadByte(I2C_I2C_ACK_DATA); MCP_temp[1] = I2C_I2CMasterReadByte(I2C_I2C_NAK_DATA); //End Transaction I2C_I2CMasterSendStop(); } / END GET_TEMP / / END FILE */ 1. Re: I2C Get Byte, Print over UARTuser_1377889 Nov 9, 2016 1:51 AM (in response to vkaiser_1860311) Welcome in the forum. At first sight: You are overwriting your OutputString which is only 2 bytes in length when you call sprintf(). Next time better post your complete project, so that we all can have a look at all of your settings. To do so, use Creator->File->Create Workspace Bundle (minimal) and attach the resulting file. Bob 2. Re: I2C Get Byte, Print over UARTvkaiser_1860311 Nov 9, 2016 6:40 AM (in response to user_1377889) Hi Bob, Thank you for that. I have attached the bundle as requested. I apologize - I don't think I'm clear on what you mean though regarding the sprintf function. My intent was to convert the two-byte read from the sensor (MCP_temp) into characters (OutputString) to output into TeraTerm. I see that it is throwing warnings. My interpretation was that the format is sprintf(output_buffer, "%format", data_to_convert), is that incorrect? Thank you for helping me to understand, I appreciate your assistance. 3. Re: I2C Get Byte, Print over UARTuser_1377889 Nov 9, 2016 7:59 AM (in response to vkaiser_1860311) Archive is not compilable, lots(!!) of projects and missing .h-files. uint32 MCP_temp[2]; This makes MCP_temp an array, thus the reference to MCP_temp is the address of that array. char OutputString[2]; This is a two-byte array. As a string, the last byte needs to carry the string terminator 0x00. sprintf(OutputString, "%lu", MCP_temp); This will fill OutputString with more than one character(!!!) thus clobbering your stack I2C: set byte mode. See attaced project. Take care not to overwrite your original. Bob 4. Re: I2C Get Byte, Print over UARTvkaiser_1860311 Nov 9, 2016 11:01 AM (in response to vkaiser_1860311) Bob, Thank you - I see that's a much more efficient way to get multiple bytes out. Thank you also for your help and comments in the data types for the variables, and the functions. I did try to use pointers while I was trying to figure this out, piecing together different examples. I'm happy to share that thanks to your help and explanations, I am reporting correct temperatures. I look forward to expanding the project (and also possibly not putting as many projects into a workspace?) Cheers! 5. Re: I2C Get Byte, Print over UARTuser_1377889 Nov 10, 2016 12:29 AM (in response to vkaiser_1860311) You are always welcome! Bob 6. Re: I2C Get Byte, Print over UARTmfarkas_1728531 Nov 16, 2016 9:58 AM (in response to vkaiser_1860311) okeee, i downloaded the code and copied it and it worked once, after i powered on and off the slave i'm trying to talk to... but once i stop the program (Psoc creator 4) and restart i get strange errors of "master not ready" from the sendstart command; upon trying it again, sometimes get a 1 ("master lost arbitration")... i don't understand how the "master" can not be ready when the only commands are: I2C_2_Start(); CyGlobalIntEnable; errStat = I2C_2_I2CMasterSendStart(0x77,I2C_2_I2C_WRITE_XFER_MODE); // this is where i get a 4 or a 1 for errStat errStat = I2C_2_I2CMasterWriteByte(0xE0); // register with device ID errStat = I2C_2_I2CMasterSendRestart(0x77,I2C_2_I2C_READ_XFER_MODE); byteRead = I2C_2_I2CMasterReadByte(I2C_2_I2C_ACK_DATA) & 0x00ff; byteRead \|= (I2C_2_I2CMasterReadByte(I2C_2_I2C_NAK_DATA) <<8) & 0x00ff; thanks for your posts 7. Re: I2C Get Byte, Print over UARTuser_1377889 Nov 16, 2016 10:17 AM (in response to vkaiser_1860311) @mfarkas: Welcome in the forum. Can you please post your complete project, so that we all can have a look at all of your settings. To do so, use Creator->File->Create Workspace Bundle (minimal) and attach the resulting file. Additionally a link to the datasheet of the device you want to talk to. Bob 8. Re: I2C Get Byte, Print over UARTmfarkas_1728531 Nov 16, 2016 11:49 AM (in response to vkaiser_1860311) wow... fast response... the data sheet has a watermark that reads "confidential", so i reckon i shouldn't attach it... btb, i re-ran it again, and even after resetting the device i got the "master lost arbitration" (a 1) error when trying to execute the restart thanks for your help 9. Re: I2C Get Byte, Print over UARTmfarkas_1728531 Nov 16, 2016 12:25 PM (in response to vkaiser_1860311) it mentions this to perform a read: 1. Write the slave address followed by the Write flag 1’b0 2. Write the register address followed by a Stop instruction 3. Write the slave address followed by the Read flag 1’b1 4. Read as many data bytes while the internal sub-address is auto-incremented i assume 1. is sendstart, 2. is writebyte, sendrestart (have tried a stop as well here) 3. is readbyte 10. Re: I2C Get Byte, Print over UARTuser_1377889 Nov 16, 2016 12:39 PM (in response to vkaiser_1860311) Set I2C to byte mode. Insert an infinite loop at end of main() to hinder a restart of the project. The error can be caused by bad hardware / pullup resistors / wrong I2C address. Best is to use a logic analyzer to watch the communication. Bob 11. Re: I2C Get Byte, Print over UARTmfarkas_1728531 Nov 16, 2016 1:38 PM (in response to vkaiser_1860311) thanks very much... i checked byte mode; i'll investigate the hardware... if i reset (unplug and plug) the psoc and power off and on the slave, the thing seems to read from it, but not expected data... thanks again matt	https://community.cypress.com/thread/12277	CC-MAIN-2017-39	refinedweb	1,233	70.02
IRC log of wot-td on 2017-07-28 Timestamps are in UTC. 06:31:17 [RRSAgent] RRSAgent has joined #wot-td 06:31:17 [RRSAgent] logging to 06:31:43 [dape] dape has joined #wot-td 06:32:03 [kaz] Meeting: WoT WG - TD-TF 06:32:14 [kaz] present+ Kaz, Dave, Koster, Uday 06:32:49 [kaz] present+ Daniel 06:33:24 [kaz] Agenda: 06:33:34 [kaz] present+ Sebastian 06:34:29 [sebastian] sebastian has joined #wot-td 06:34:39 [dsr] dsr has joined #wot-td 06:35:02 [mjkoster] mjkoster has joined #wot-td 06:35:09 [dsr] present+ 06:35:44 [kaz] scribenick: mjkoster 06:35:51 [kaz] regrets: Maria, Soumya 06:36:01 [uday] uday has joined #wot-td 06:36:25 [kaz] regrets+ Benjamin 06:36:51 [mjkoster] sebastian: invited Mozilla to talk about their TD proposal 06:36:58 [DarkoAnicic] DarkoAnicic has joined #wot-td 06:37:04 [DarkoAnicic] present+ DarkoAnicic 06:37:15 [kaz] -> July 26 main call minutes 06:37:43 [mjkoster] ...topics: what is our feedback on the Mozilla proposal? 06:38:02 [mjkoster] ...what is needed in the TD update? 06:38:06 [kaz] i\|invited Mozilla\|topic: Summary of Wednesday's call about the member submission of Mozilla --> what are the next steps?\| 06:38:10 [mjkoster] ... vocabulary 06:38:43 [mjkoster] ... issues and current status 06:38:54 [mjkoster] .. any other topics? 06:39:23 [mjkoster] ...1st point, what was the outcome? 06:39:26 [kaz] s\|topic: Summary of Wednesday's call about the member submission of Mozilla --> what are the next steps?\|topic: Agenda bashing\| 06:39:39 [kaz] topic: Summary of Wednesday's call about the member submission of Mozilla --> what are the next steps? 06:39:41 [mjkoster] s/outcome/outcome of the Mozilla discussion 06:40:05 [kaz] -> July 26 minutes 06:40:18 [kaz] q+ 06:40:58 [kaz] -> Ben's blog 06:41:25 [mjkoster] dsr: Mozilla prefer to contribute to the IG, since the approach is still being developed 06:41:30 [kaz] -> Ben's proposal 06:42:46 [mjkoster] sebastian: the Mozilla proposal is similar to Dave's proposal 06:45:39 [DarkoAnicic] q+ 06:45:39 [kaz] present+ Achille_Zappa 06:45:45 [dape] q+ 06:45:46 [mjkoster] mkoster: Mozilla produced an example with @context and @type used as an extension 06:46:07 [kaz] q? 06:47:19 [mjkoster] sebastian: seems like syntactic sugar 06:47:30 [kaz] ack darko 06:47:34 [mjkoster] dsr: syntactic sugar is important to developers 06:48:27 [mjkoster] darko: the reason for using RDF is extension to the harder use cases 06:48:44 [dsr] [We’ve seen the importance of notations with the dominance of Turtle vs RDF/XML and JSON vs XML 06:49:08 [mjkoster] darko: RDF is needed to process the data in the more complex applications 06:49:29 [yongjing] yongjing has joined #wot-td 06:49:44 [kaz] q- 06:49:45 [kaz] q+ 06:50:05 [dsr] +q to note that it is very easy to formally convert JSON to triples using default context and a simple algorthm - we can easily apply validation and semantic processing 06:50:10 [mjkoster] darko: the usefulness for industry applications is more important than the way the file looks 06:51:04 [mjkoster] sebastian: there should be a default mapping to RDF from the simple json 06:51:16 [kaz] present+ Yongjing 06:52:37 [kaz] w? 06:52:39 [kaz] q? 06:52:41 [kaz] s/w?/ 06:53:28 [mjkoster] dape: same comment as darko, the difference is marginal and potential large impact 06:54:08 [mjkoster] dape: can JSON-LD 1.1 and shape languages work together? 06:54:39 [mjkoster] dsr: shape constraints work on triples, so yes 06:55:16 [dape] ack dape 06:55:33 [mjkoster] sebastian: would like to hear from schema.org 06:56:17 [mjkoster] darko: they use rdfa on web pages 06:56:36 [kaz] q? 06:57:04 [kaz] ack k 06:57:13 [mjkoster] sebastian: the Mozilla proposal doesn't focus on mapping to RDF 06:57:27 [dsr] q- 06:58:10 [mjkoster] kaz: to summarize, Mozilla was not interested in scripting API but is interested in TD serialization and protocol binding 06:58:12 [dsr] q+ 06:59:07 [kaz] kaz: @@2 06:59:15 [mjkoster] ... Matthias asked Mozilla to bring specific proposals to the IG, we can evaluate them at that time 06:59:47 [kaz] s/kaz: @@2// 07:00:30 [kaz] q? 07:00:33 [kaz] ack d 07:00:34 [victor] victor has joined #wot-td 07:00:55 [mjkoster] q+ 07:01:16 [kaz] s/at that time/at that time. I also asked him to join the IG officially and he's now checking within Mozilla for the procedure./ 07:01:28 [kaz] ack m 07:02:04 [achille_zappa] achille_zappa has joined #wot-td 07:03:08 [kaz] present+ Victor 07:04:21 [mjkoster] sebastian: also having the serialization discussion JSON-LD vs. ttl in iotschema 07:04:23 [achille_zappa] achille_zappa has joined #wot-td 07:04:29 [mjkoster] s/ttl/turtle 07:04:54 [mjkoster] topic: next TD deliverables 07:05:38 [mjkoster] ...dsr proposal for organizing deliverables; issue 19 07:06:15 [kaz] -> issue 19 07:06:19 [mjkoster] dsr: follow best practices for vocabularies 07:07:41 [mjkoster] dsr: specification document describing the vocabulary and serialization 07:10:13 [mjkoster] victor: wrote a script to generate tables from the vocabulary files 07:10:21 [kaz] -> @@@ victor's write-up tbd 07:10:31 [kaz] q+ 07:11:41 [mjkoster] victor: update the turtle file and automatically generate the HTML 07:12:22 [dape] q+ mention primer info 07:12:28 [dape] q+ 07:12:48 [kaz] ack k 07:13:29 [mjkoster] kaz: would victor send the information to the member list? 07:13:44 [victor] 07:14:07 [mjkoster] kaz: also send email 07:14:41 [dsr] q+ to ask if we should put the script into the HTML for autogeneration of the vocab entries 07:14:54 [mjkoster] kaz: to clarify, the Mozilla document is not a member submission 07:15:05 [kaz] s/to clarify/btw, to clarify/ 07:15:36 [mjkoster] dape: should there be a quick start in the beginning of the document, or a separate document? 07:16:01 [kaz] s/not a member submission/not an official W3C Member submission though it used the specific CSS and had a title of "member submission"./ 07:16:04 [mjkoster] dsr: agree on separate primer document 07:16:54 [mjkoster] sebastian: JSON-LD has a good example of a primer 07:19:18 [dape] ack dape 07:19:47 [mjkoster] kaz: editor meeting doodle in progress, waiting for all of the responses 07:20:14 [mjkoster] ...so far August 2nd, 1pm Europe time 07:21:05 [mjkoster] topic: vocabularies in the TD name space 07:21:37 [kaz] -> TD namespace file 07:22:45 [mjkoster] issues around how to organize the HTML, htaccess, etc 07:23:56 [mjkoster] victor: we need to decide on content negotiation for a set of media types 07:24:48 [mjkoster] s/types/types and directories 07:25:53 [mjkoster] kaz: clarify our requirements and talk with the W3C system team 07:26:32 [dsr] Best practice recipes for publishing RDF vocabularies 07:27:43 [dsr] which talks about apache .htaccess files 07:27:44 [DarkoAnicic] q+ 07:27:48 [dsr] q- 07:29:05 [DarkoAnicic] WoT Onotolgy (current location): already serves few formats, e.g., turtle, XML... 07:32:11 [mjkoster] topic: iotschema vocabulary 07:32:39 [kaz] -> issue 18 07:32:59 [victor] q+ 07:33:07 [mjkoster] sebastian: organize a plan of action so we can track the activity 07:33:11 [dsr] ack Dar 07:33:59 [kaz] s/clarify our requirements/let's clarify our requirements, e.g., on the Member list (member-wot-wg@w3.org)/ 07:34:05 [mjkoster] ...including milestones 07:34:44 [mjkoster] ...also report/tracking of the protocol binding activity 07:35:04 [kaz] s/Europe time/Europe time is the best candidate because all the responded Editors can make it./ 07:35:15 [kaz] q? 07:35:18 [mjkoster] ...also would like to set up the same for TD serialization 07:36:00 [mjkoster] ...metadata for protocol bindings and dynamic URIs - discussion for 3 weeks from now 07:36:30 [mjkoster] ...JSON-schema to RDF 07:37:05 [mjkoster] ...use github milestones 07:37:51 [kaz] q? 07:38:06 [kaz] ack v 07:38:58 [kaz] [ adjourned ] 07:39:13 [kaz] rrsagent, make log public 07:39:17 [kaz] rrsagent, draft minutes 07:39:17 [RRSAgent] I have made the request to generate kaz 07:48:52 [naka] naka has joined #wot-td	http://www.w3.org/2017/07/28-wot-td-irc	CC-MAIN-2021-43	refinedweb	1,483	60.89
This action might not be possible to undo. Are you sure you want to continue? Introduction to Natural Language Processing 1.1 The Language Challenge Today, people from all walks of life including professionals, students, and the general population are confronted by unprecedented volumes of information, the vast bulk of which is stored as unstructured text. In 2003, it was estimated that the annual production of books amounted to 8 Terabytes. (A Terabyte is 1,000 Gigabytes, i.e., equivalent to 1,000 pickup trucks ﬁlled with books.) It would take a human being about ﬁve years to read the new scientiﬁc material that is produced every 24 hours. Although these estimates are based on printed materials, increasingly the information is also available electronically. Indeed, there has been an explosion of text and multimedia content on the World Wide Web. For many people, a large and growing fraction of work and leisure time is spent navigating and accessing this universe of information. The presence of so much text in electronic form is a huge challenge to NLP. Arguably, the only way for humans to cope with the information explosion is to exploit computational techniques that can sift through huge bodies of text. Although existing search engines have been crucial to the growth and popularity of the Web, humans require skill, knowledge, and some luck, to extract answers to such questions as What tourist sites can I visit between Philadelphia and Pittsburgh on a limited budget? What do expert critics say about digital SLR cameras? What predictions about the steel market were made by credible commentators in the past week? Getting a computer to answer them automatically is a realistic longterm goal, but would involve a range of language processing tasks, including information extraction, inference, and summarization, and would need to be carried out on a scale and with a level of robustness that is still beyond our current capabilities. 1.1.1 The Richness of Language Language is the chief manifestation of human intelligence. Through language we express basic needs and lofty aspirations, technical know-how and ﬂights of fantasy. Ideas are shared over great separations of distance and time. The following samples from English illustrate the richness of language: (1) a. Overhead the day drives level and grey, hiding the sun by a ﬂight of grey spears. (William Faulkner, As I Lay Dying, 1935) 1 1.1. The Language Challenge b. When using the toaster please ensure that the exhaust fan is turned on. (sign in dormitory kitchen) c. Amiodarone weakly inhibited CYP2C9, CYP2D6, and CYP3A4-mediated activities with Ki values of 45.1-271.6 ¼M (Medline, PMID: 10718780) d. Iraqi Head Seeks Arms (spoof news headline) e. The earnest prayer of a righteous man has great power and wonderful results. (James 5:16b) f. Twas brillig, and the slithy toves did gyre and gimble in the wabe (Lewis Carroll, Jabberwocky, 1872) g. There are two ways to do this, AFAIK :smile: (internet discussion archive) Thanks to this richness, the study of language is part of many disciplines outside of linguistics, including translation, literary criticism, philosophy, anthropology and psychology. Many less obvious disciplines investigate language use, such as law, hermeneutics, forensics, telephony, pedagogy, archaeology, cryptanalysis and speech pathology. Each applies distinct methodologies to gather observations, develop theories and test hypotheses. Yet all serve to deepen our understanding of language and of the intellect that is manifested in language. The importance of language to science and the arts is matched in signiﬁcance by the cultural treasure embodied in language. Each of the world’s ~7,000 human languages is rich in unique respects, in its oral histories and creation legends, down to its grammatical constructions and its very words and their nuances of meaning. Threatened remnant cultures have words to distinguish plant subspecies according to therapeutic uses that are unknown to science. Languages evolve over time as they come into contact with each other and they provide a unique window onto human pre-history. Technological change gives rise to new words like blog and new morphemes like e- and cyber-. In many parts of the world, small linguistic variations from one town to the next add up to a completely different language in the space of a half-hour drive. For its breathtaking complexity and diversity, human language is as a colorful tapestry stretching through time and space. 1.1.2 The Promise of NLP As we have seen, NLP is important for scientiﬁc, economic, social, and cultural reasons. NLP is experiencing rapid growth as its theories and methods are deployed in a variety of new language technologies. For this reason it is important for a wide range of people to have a working knowledge of NLP. Within industry, it includes people in human-computer interaction, business information analysis, and Web software development. Within academia, this includes people in areas from humanities computing and corpus linguistics through to computer science and artiﬁcial intelligence. We hope that you, a member of this diverse audience reading these materials, will come to appreciate the workings of this rapidly growing ﬁeld of NLP and will apply its techniques in the solution of real-world problems. The following chapters present a carefully-balanced selection of theoretical foundations and practical applications, and equips readers to work with large datasets, to create robust models of linguistic phenomena, and to deploy them in working language technologies. By integrating all of this into the Natural Language Toolkit (NLTK), we hope this book opens up the exciting endeavor of practical natural language processing to a broader audience than ever before. January 24, 2008 2 Bird, Klein & Loper 1. Introduction to Natural Language Processing Introduction to Natural Language Processing (DRAFT) 1.2 1.2.1 Language and Computation NLP and Intelligence A long-standing challenge within computer science has been to build intelligent machines. The chief measure of machine intelligence has been a linguistic one, namely the Turing Test: can a dialogue system, responding to a user’s typed input with its own textual output, perform so naturally that users cannot distinguish it from a human interlocutor using the same interface? Today, there is substantial ongoing research and development in such areas as machine translation and spoken dialogue, and signiﬁcant commercial systems are in widespread use. The following dialogue illustrates a typical application: (2) S: How may I help you? U: When is Saving Private Ryan playing? S: For what theater? U: The Paramount theater. S: Saving Private Ryan is not playing at the Paramount theater, but it’s playing at the Madison theater at 3:00, 5:30, 8:00, and 10:30. Today’s commercial dialogue systems are strictly limited to narrowly-deﬁned domains. We could not ask the above system to provide driving instructions or details of nearby restaurants unless the requisite information had already been stored and suitable question and answer sentences had been incorporated into the language processing system. Observe that the above system appears to understand the user’s goals: the user asks when a movie is showing and the system correctly determines from this that the user wants to see the movie. This inference seems so obvious to humans that we usually do not even notice it has been made, yet a natural language system needs to be endowed with this capability in order to interact naturally. Without it, when asked Do you know when Saving Private Ryan is playing, a system might simply and unhelpfully respond with a cold Yes. While it appears that this dialogue system can perform simple inferences, such sophistication is only found in cutting edge research prototypes. Instead, the developers of. This is sufﬁcient for the system to provide a useful service. As NLP technologies become more mature, and robust methods for analysing unrestricted text become more widespread, the prospect of natural language ’understanding’ has re-emerged as a plausible goal. This has been brought into focus in recent years by a public ’shared task’ called Recognizing Textual Entailment (RTE) [Quinonero-Candela et al, 2006]. The basic scenario is simple. Let’s suppose we are interested in whether we can ﬁnd evidence to support a hypothesis such as Sandra Goudie was defeated by Max Purnell. We are given another short text that appears to be relevant, for example, Sandra Goudie was ﬁrst elected to Parliament in the 2002 elections, narrowly winning the seat of Coromandel by defeating Labour candidate Max Purnell and pushing incumbent Green MP Jeanette Fitzsimons into third place. The question now is whether the text provides sufﬁcient evidence for us to accept the hypothesis as true. In this particular case, the answer is No. This is a conclusion that we can draw quite easily as humans, but it is very hard to come up with automated methods for making the right classiﬁcation. The RTE Challenges provide data which allow competitors to develop their systems, but Bird, Klein & Loper 3 January 24, 2008 1.2. Language and Computation not enough data to allow statistical classiﬁers to be trained using standard machine learning techniques. Consequently, some linguistic analysis is crucial. In the above example, it is important for the system to note that Sandra Goudie names the person being defeated in the hypothesis, but the person doing the defeating in the text. As another illustration of the difﬁculty of the task, consider the following text/hypothesis pair: David Golinkin is the editor or author of eighteen books, and over 150 responsa, articles, sermons and books Golinkin has written eighteen books In order to determine whether or not the hypothesis is supported by the text, the system needs at least the following background knowledge: (i) if someone is an author of a book, then he/she has written that book; (ii) if someone is an editor of a book, then he/she has not written that book; (iii) if someone is editor or author of eighteen books, then he/she is not author of eighteen books. Despite the research-led advances in tasks like RTE, natural language systems that have been deployed for real-world applications still cannot perform common-sense reasoning or draw on world knowledge in a general and robust manner. We can wait for these difﬁcult artiﬁcial intelligence problems to be solved, but in the meantime it is necessary to live with some severe limitations on the reasoning and knowledge capabilities of natural language systems. Accordingly, right from the beginning, an important goal of NLP research has been to make progress on the holy grail of natural linguistic interaction without recourse to this unrestricted knowledge and reasoning capability. This is an old challenge, and so it is instructive to review the history of the ﬁeld. 1.2.2 Language and Symbol Processing ﬁrst was formal language theory. This deﬁned-deﬁned syntax and semantics, it becomes possible to associate meanings with expressions of natural language by translating them into expressions of the formal calculus. For example, if we translate John saw Mary into a formula saw(j,m), we (implicitly or explicitly) intepret the English verb saw as a binary relation, and John and Mary as denoting individuals. More general statements like All birds ﬂy require quantiﬁers, in this case , meaning for all: x(bird(x) ’ f ly. This principle provided a useful correspondence between syntax and semantics, namely that the meaning of a complex expression could be computed recursively. Consider the sentence It is not true that p, where January 24, 2008 4 Bird, Klein & Loper 1. Introduction to Natural Language Processing Introduction to Natural Language Processing (DRAFT) above practioners of NLP, leading to a family of grammar formalisms known as uniﬁcation-based (or feature-based) grammar, and to NLP applications implemented in the Prolog programming language. Although grammar-based NLP is still a signiﬁcant area of research, it has become somewhat eclipsed in the last 15 20 years due to a variety of factors. One signiﬁcant inﬂuence came from automatic speech recognition. Although early work in speech processing adopted a model that emulated the kind of rulebased phonological processing typiﬁed by the Sound Pattern of English [Chomsky & Halle, 1968], this turned out to be hopelessly inadequate in dealing with the hard problem of recognizing actual speech in anything like real time. By contrast, systems which involved learning patterns from large bodies of speech data were signiﬁcantly more accurate, efﬁcient. 1.2.3 Philosophical Divides seventeenth and eighteenth centuries, philosophers argued that human reason or sensory experience has priority over revelation. Descartes and Leibniz, amongst reﬂecting on that experience. Prototypical matter surfaces as differences in the priority of corpus data versus linguistic introspection in the construction of computational models. We will return to this issue later in the book. Bird, Klein & Loper 5 January 24, 2008 1.3. The Architecture of Linguistic and NLP Systems ﬁctions. The way linguists write about theories often betrays a realist position,iﬁcations, and scientiﬁc vs to use these methods to identify meaningful patterns in their sensory language experience (empiricism). For a more concrete illustration, consider the way in which statistics from large corpora may serve as evidence for binary choices in a symbolic grammar. For instance, dictionaries describe the words absolutely and deﬁnitely as nearly synonymous, yet their patterns of usage are quite distinct when combined with a following verb, as shown in Table 1.1. Google hits absolutely deﬁnitely ratio adore love like prefer 289,000 905,000 16,200 644 1,460 51,000 158,000 62,600 198:1 18:1 1:10 1:97 Table 1.1: Absolutely vs Deﬁnitely (Liberman 2005, LanguageLog.org) As you will see, absolutely adore is about 200 times as popular as deﬁnitely adore, while absolutely prefer is about 100 times rarer then deﬁnitely prefer. This information is used by statistical language models, but it also counts as evidence for a symbolic account of word combination in which absolutely can only modify extreme actions or attributes, a property that could be represented as a binary-valued feature of certain lexical items. Thus, we see statistical data informing symbolic models. Once this information has been codiﬁed symbolically, it is available to be exploited as a contextual feature for statistical language modeling, alongside many other rich sources of symbolic information, like handconstructed parse trees and semantic representations. Now the circle is closed, and we see symbolic information informing statistical models. This new rapprochement is giving rise to many exciting new developments. We will touch on some of these in the ensuing pages. We too will perform this balancing act, employing approaches to NLP that integrate these historically-opposed philosophies and methodologies. 1.3 1.3.1 The Architecture of Linguistic and NLP Systems Generative Grammar and Modularity One of the intellectual descendants of formal language theory was the linguistic framework known as generative grammar. Such a grammar contains a set of rules that recursively specify (or generate) the set of well-formed strings in a language. While there is a wide spectrum of models that owe some allegiance to this core, Chomsky’s transformational grammar, in its various incarnations, is probably the best known. In the Chomskyan tradition, it is claimed that humans have distinct kinds of linguistic knowledge, organized into different modules: for example, knowledge of a language’s sound structure January 24, 2008 6 Bird, Klein & Loper 1. Introduction to Natural Language Processing Introduction to Natural Language Processing (DRAFT) (phonology), knowledge of word structure (morphology), knowledge of phrase structure (syntax), and knowledge of meaning (semantics). In a formal linguistic theory, each kind of linguistic knowledge is made explicit as different module of the theory, consisting of a collection of basic elements together with a way of combining them into complex structures. For example, deﬁning complex elements, is often called a level of representation. As well as deﬁning modules, a generative grammar will prescribe how the modules interact. For example, well-formed phonological strings will provide the phonological content of words, and words will provide the terminal elements of syntax trees. Well-formed syntactic trees will be mapped to semantic representations, and contextual or pragmatic information will ground these semantic representations in some real-world situation. As we indicated above, an important aspect of theories of generative grammar is that they are intended to model the linguistic knowledge of speakers and hearers; they are not intended to explain how humans actually process linguistic information. This is, in part, reﬂected in the claim that a generative grammar encodes the competence of an idealized native speaker, rather than the speaker’s performance. A closely related distinction is to say that a generative grammar encodes declarative rather than procedural knowledge. Declarative knowledge can be glossed as “knowing what”, whereas procedural knowledge is “knowing how”. As you might expect, computational linguistics has the crucial role of proposing procedural models of language. A central example is parsing, where we have to develop computational mechanisms that convert strings of words into structural representations such as syntax trees. Nevertheless, it is widely accepted that well-engineered computational models of language contain both declarative and procedural aspects. Thus, a full account of parsing will say how declarative knowledge in the form of a grammar and lexicon combines with procedural knowledge that determines how a syntactic analysis should be assigned to a given string of words. This procedural knowledge will be expressed as an algorithm: that is, an explicit recipe for mapping some input into an appropriate output in a ﬁnite number of steps. A simple parsing algorithm for context-free grammars, for instance, looks ﬁrst for a rule of the form S ’ X1 ... Xn , and builds a partial tree structure. It then steps through the grammar rules one-by-one, looking for a rule of the form X1 ’ Y1 ... Y j that will expand the leftmost daughter introduced by the S rule, and further extends the partial tree. This process continues, for example by looking for a rule of the form Y1 ’ Z1 ... Zk and expanding the partial tree appropriately, until the leftmost node label in the partial tree is a lexical category; the parser then checks to see if the ﬁrst word of the input can belong to the category. To illustrate, let’s suppose that the ﬁrst grammar rule chosen by the parser is S ’ NP VP and the second rule chosen is NP ’ Det N; then the partial tree will be as follows: (3) If we assume that the input string we are trying to parse is the cat slept, we will succeed in identifying the as a word that can belong to the category D ET. In this case, the parser goes on to the next node of the tree, N, and next input word, cat. However, if we had built the same partial tree with an input string did the cat sleep, the parse would fail at this point, since did is not of category D ET. Bird, Klein & Loper 7 January 24, 2008 1.3. The Architecture of Linguistic and NLP Systems The parser would throw away the structure built so far and look for an alternative way of going from the S node down to a leftmost lexical category (e.g., using a rule S ’ V NP VP). The important point for now is not the details of this or other parsing algorithms; we discuss this topic much more fully in the chapter on parsing. Rather, we just want to illustrate the idea that an algorithm can be broken down into a ﬁxed number of steps that produce a deﬁnite result at the end. In Figure 1.1 we further illustrate some of these points in the context of a spoken dialogue system, such as our earlier example of an application that offers the user information about movies currently on show. Figure 1.1: Simple Pipeline Architecture for a Spoken Dialogue System Along the top of the diagram, moving from left to right, is a “pipeline” of some representative speech understanding components. These map from speech input via syntactic parsing to some kind of meaning representation. Along the middle, moving from right to left, is an inverse pipeline of components for concept-to-speech generation. These components constitute the dynamic or procedural aspect of the system’s natural language processing. At the bottom of the diagram are some representative bodies of static information: the repositories of language-related data that are called upon by the processing components. The diagram illustrates that linguistically-motivated ways of modularizing linguistic knowledge are often reﬂected in computational systems. That is, the various components are organized so that the data which they exchange corresponds roughly to different levels of representation. For example, the output of the speech analysis component will contain sequences of phonological representations of words, and the output of the parser will be a semantic representation. Of course the parallel is not precise, in part because it is often a matter of practical expedience where to place the boundaries between different processing components. For example, we can assume that within the parsing component there is a level of syntactic representation, although we have chosen not to expose this at the level of the system diagram. Despite such idiosyncrasies, most NLP systems break down their work into a series of discrete steps. In the process of natural language understanding, these steps go from more concrete levels to more abstract ones, while in natural language production, the direction is reversed. January 24, 2008 8 Bird, Klein & Loper 1. Introduction to Natural Language Processing Introduction to Natural Language Processing (DRAFT) 1.4 Before Proceeding Further... An important aspect of learning NLP using these materials is to experience both the challenge and we hope the satisfaction of creating software to process natural language. The accompanying software, NLTK, is available for free and runs on most operating systems including Linux/Unix, Mac OSX and Microsoft Windows. You can download NLTK from, along with extensive documentation. We encourage you to install Python and NLTK on your machine before reading beyond the end of this chapter. 1.5 Further Reading Several websites have useful information about NLP, including conferences, resources, and specialinterest groups, e.g.,,. The website of the Association for Computational Linguistics, at, contains an overview of computational linguistics, including copies of introductory chapters from recent textbooks. Wikipedia has entries for NLP and its subﬁelds (but don’t confuse natural language processing with the other NLP: neuro-linguistic programming.) Three books provide comprehensive surveys of the ﬁeld: [Cole, 1997], [Dale, Moisl, & Somers, 2000], [Mitkov, 2002]. Several NLP systems have online interfaces that you might like to experiment with, e.g.: WordNet: Translation: ChatterBots: Question Answering: Summarization: Bird, Klein & Loper 9 January 24, 2008 Chapter 2 Programming Fundamentals and Python This chapter provides a non-technical overview of Python and will cover the basic programming knowledge needed for the rest of the chapters in Part 1. It contains many examples and exercises; there is no better way to learn to program than to dive in and try these yourself. You should then feel conﬁdent in adapting the example for your own purposes. Before you know it you will be programming! 2.1 Getting Started One of the friendly things about Python is that it allows you to type directly into the interactive interpreter the program that will be running your Python programs. You can run the Python interpreter using a simple graphical interface called the Interactive DeveLopment Environment (IDLE). On a Mac you can ﬁnd this under Applications -> MacPython, and on Windows under All Programs -> Python. Under Unix you can run Python from the shell by typing python. The interpreter will print a blurb about your Python version; simply check that you are running Python 2.4 or greater (here it is 2.5): Python 2.5 (r25:51918, Sep 19 2006, 08:49:13) [GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> Note If you are unable to run the Python interpreter, you probably don’t have Python installed correctly. Please visit for detailed instructions. The >>> prompt indicates that the Python interpreter is now waiting for input. Let’s begin by using the Python prompt as a calculator: >>> 3 + 2 * 5 - 1 12 >>> There are several things to notice here. First, once the interpreter has ﬁnished calculating the answer and displaying it, the prompt reappears. This means the Python interpreter is waiting for another instruction. Second, notice that Python deals with the order of operations correctly (unlike some older calculators), so the multiplication 2 * 5 is calculated before it is added to 3. 1 2.2. Understanding the Basics: Strings and Variables Try a few more expressions of your own. You can use asterisk () for multiplication and slash (/) for division, and parentheses for bracketing expressions. One strange thing you might come across is that division doesn’t always behave how you expect: >>> 3/3 1 >>> 1/3 0 >>> The second case is surprising because we would expect the answer to be 0.333333. We will come back to why that is the case later on in this chapter. For now, let’s simply observe that these examples demonstrate how you can work interactively with the interpreter, allowing you to experiment and explore. Also, as you will see later, your intuitions about numerical expressions will be useful for manipulating other kinds of data in Python. You should also try nonsensical expressions to see how the interpreter handles it: >>> 1 + Traceback (most recent call last): File "<stdin>", line 1 1 + ^ SyntaxError: invalid syntax >>> Here we have produced a syntax error. It doesn’t make sense to end an instruction with a plus sign. The Python interpreter indicates the line where the problem occurred. 2.2 2.2.1 Understanding the Basics: Strings and Variables Representing text We can’t simply type text directly into the interpreter because it would try to interpret the text as part of the Python language: >>> Hello World Traceback (most recent call last): File "<stdin>", line 1 Hello World ^ SyntaxError: invalid syntax >>> Here we see an error message. Note that the interpreter is confused about the position of the error, and points to the end of the string rather than the start. Python represents a piece of text using a string. Strings are delimited or separated from the rest of the program by quotation marks: >>> ’Hello World’ ’Hello World’ >>> "Hello World" ’Hello World’ >>> January 24, 2008 2 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) We can use either single or double quotation marks, as long as we use the same ones on either end of the string. Now we can perform calculator-like operations on strings. For example, adding two strings together seems intuitive enough that you could guess the result: >>> ’Hello’ + ’World’ ’HelloWorld’ >>> When applied to strings, the + operation is called concatenation. It produces a new string that is a copy of the two original strings pasted together end-to-end. Notice that concatenation doesn’t do anything clever like insert a space between the words. The Python interpreter has no way of knowing that you want a space; it does exactly what it is told. Given the example of +, you might be able guess what multiplication will do: >>> ’Hi’ + ’Hi’ + ’Hi’ ’HiHiHi’ >>> ’Hi’ 3 ’HiHiHi’ >>> The point to take from this (apart from learning about strings) is that in Python, intuition about what should work gets you a long way, so it is worth just trying things to see what happens. You are very unlikely to break anything, so just give it a go. 2.2.2 Storing and Reusing Values After a while, it can get quite tiresome to keep retyping Python statements over and over again. It would be nice to be able to store the value of an expression like ’Hi’ + ’Hi’ + ’Hi’ so that we can use it again. We do this by saving results to a location in the computer’s memory, and giving the location a name. Such a named place is called a variable. In Python we create variables by assignment, which involves putting a value into the variable: >>> msg = ’Hello World’ >>> msg ’Hello World’ >>> ` a b In line ` we have created a variable called msg (short for ’message’) and set it to have the string value ’Hello World’. We used the = operation, which assigns the value of the expression on the right to the variable on the left. Notice the Python interpreter does not print any output; it only prints output when the statement returns a value, and an assignment statement returns no value. In line a we inspect the contents of the variable by naming it on the command line: that is, we use the name msg. The interpreter prints out the contents of the variable in line b. Variables stand in for values, so instead of writing ’Hi’ * 3 we could assign variable msg the value ’Hi’, and num the value 3, then perform the multiplication using the variable names: >>> msg = ’Hi’ >>> num = 3 >>> msg * num ’HiHiHi’ >>> Bird, Klein & Loper 3 January 24, 2008 2.2. Understanding the Basics: Strings and Variables The names we choose for the variables are up to us. Instead of msg and num, we could have used any names we like: >>> marta = ’Hi’ >>> foo123 = 3 >>> marta * foo123 ’HiHiHi’ >>> Thus, the reason for choosing meaningful variable names is to help you and anyone who reads your code to understand what it is meant to do. Python does not try to make sense of the names; it blindly follows your instructions, and does not object if you do something potentially confusing such as assigning a variable two the value 3, with the assignment statement: two = 3. Note that we can also assign a new value to a variable just by using assignment again: >>> msg = msg * num >>> msg ’HiHiHi’ >>> Here we have taken the value of msg, multiplied it by 3 and then stored that new string (HiHiHi) back into the variable msg. 2.2.3 Printing and Inspecting Strings So far, when we have wanted to look at the contents of a variable or see the result of a calculation, we have just typed the variable name into the interpreter. We can also see the contents of msg using print msg: >>> msg = ’Hello World’ >>> msg ’Hello World’ >>> print msg Hello World >>> On close inspection, you will see that the quotation marks that indicate that Hello World is a string are missing in the second case. That is because inspecting a variable, by typing its name into the interactive interpreter, prints out the Python representation of a value. In contrast, the print statement only prints out the value itself, which in this case is just the text contained in the string. In fact, you can use a sequence of comma-separated expressions in a print statement: >>> msg2 = ’Goodbye’ >>> print msg, msg2 Hello World Goodbye >>> Note If you have created some variable v and want to ﬁnd out about it, then type help (v) to read the help entry for this kind of object. Type dir(v) to see a list of operations that are deﬁned on the object. January 24, 2008 4 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) You need to be a little bit careful in your choice of names (or identiﬁers) for Python variables. Some of the things you might try will cause an error. First, you should start the name with a letter, optionally followed by digits (0 to 9) or letters. Thus, abc23 is ﬁne, but 23abc will cause a syntax error. You can use underscores (both within and at the start of the variable name), but not a hyphen, since this gets interpreted as an arithmetic operator. A second problem is shown in the following snippet. >>> not = "don’t do this" File "<stdin>", line 1 not = "don’t do this" ^ SyntaxError: invalid syntax Why is there an error here? Because not is reserved as one of Python’s 30 odd keywords. These are special identiﬁers that are used in speciﬁc syntactic contexts, and cannot be used as variables. It is easy to tell which words are keywords if you use IDLE, since they are helpfully highlighted in orange. 2.2.4 Creating Programs with a Text Editor The Python interative: msg = ’Hello World’ Save this program in a ﬁle called test.py, then go to the Run menu, and select the command Run Module. The result in the main IDLE window should look like this: >>> ================================ RESTART ================================ >>> >>> Now, where is the output showing the value of msg? The answer is that the program in test.py will show a value only if you explicitly tell it to, using the print command. So add another line to test.py so that it looks as follows: msg = ’Hello World’ print msg Select Run Module again, and this time you should get output that looks like this: >>> ================================ RESTART ================================ >>> Hello World >>> From now on, you have a choice of using the interactive interpreter or a text editor to create your programs. It is often convenient to test your ideas using the interpreter, revising a line of code until it does what you expect, and consulting the interactive help facility. Once you’re ready, you can paste the code (minus any >>> prompts) into the text editor, continue to expand it, and ﬁnally save the program in a ﬁle so that you don’t have to retype it in again later. Bird, Klein & Loper 5 January 24, 2008 2.3. Slicing and Dicing 2.2.5 Exercises 1. < Start up the Python interpreter (e.g. by running IDLE). Try the examples in section 2.1, then experiment with using Python as a calculator. 2. < Try the examples in this section, then try the following. a) Create a variable called msg and put a message of your own in this variable. Remember that strings need to be quoted, so you will need to type something like: >>> msg = "I like NLP!" b) Now print the contents of this variable in two ways, ﬁrst by simply typing the variable name and pressing enter, then by using the print command. c) Try various arithmetic expressions using this string, e.g. msg + msg, and 5 * msg. d) Deﬁne a new string hello, and then try hello + msg. Change the hello string so that it ends with a space character, and then try hello + msg again. 2.3 Slicing and Dicing Strings are so important that we will spend some more time on them. Here we will learn how to access the individual characters that make up a string, how to pull out arbitrary substrings, and how to reverse strings. 2.3.1 Accessing Individual Characters The positions within a string are numbered, starting from zero. To access a position within a string, we specify the position inside square brackets: >>> >>> ’H’ >>> ’l’ >>> ’ ’ >>> msg = ’Hello World’ msg[0] msg[3] msg[5] This is called indexing or subscripting the string. The position we specify inside the square brackets is called the index. We can retrieve not only letters but any character, such as the space at index 5. Note Be careful to distinguish between the string ’ ’, which is a single whitespace character, and ’’, which is the empty string. The fact that strings are indexed from zero may seem counter-intuitive. You might just want to think of indexes as giving you the position in a string immediately before a character, as indicated in Figure 2.1. Now, what happens when we try to access an index that is outside of the string? January 24, 2008 6 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) Figure 2.1: String Indexing >>> msg[11] Traceback (most recent call last): File "<stdin>", line 1, in ? IndexError: string index out of range >>> The index of 11 is outside of the range of valid indices (i.e., 0 to 10) for the string ’Hello World’. This results in an error message. This time it is not a syntax error; the program fragment is syntactically correct. Instead, the error occurred while the program was running. The Traceback message indicates which line the error occurred on (line 1 of “standard input”). It is followed by the name of the error, IndexError, and a brief explanation. In general, how do we know what we can index up to? If we know the length of the string is n, the highest valid index will be n − 1. We can get access to the length of the string using the built-in len( ) function. >>> len(msg) 11 >>> Informally, a function is a named snippet of code that provides a service to our program when we call or execute it by name. We call the len() function by putting parentheses after the name and giving it the string msg we want to know the length of. Because len() is built into the Python interpreter, IDLE colors it purple. We have seen what happens when the index is too large. What about when it is too small? Let’s see what happens when we use values less than zero: >>> msg[-1] ’d’ >>> This does not generate an error. Instead, negative indices work from the end of the string, so -1 indexes the last character, which is ’d’. >>> msg[-3] ’r’ >>> msg[-6] ’ ’ >>> Now the computer works out the location in memory relative to the string’s address plus its length, subtracting the index, e.g. 3136 + 11 - 1 = 3146. We can also visualize negative indices as shown in Figure 2.2. Thus we have two ways to access the characters in a string, from the start or the end. For example, we can access the space in the middle of Hello and World with either msg[5] or msg[-6]; these refer to the same location, because 5 = len(msg) - 6. Bird, Klein & Loper 7 January 24, 2008 2.3. Slicing and Dicing Figure 2.2: Negative Indices 2.3.2 Accessing Substrings In NLP we usually want to access more than one character at a time. This is also pretty simple; we just need to specify a start and end index. For example, the following code accesses the substring starting at index 1, up to (but not including) index 4: >>> msg[1:4] ’ell’ >>> The notation :4 is known as a slice. Here we see the characters are ’e’, ’l’ and ’l’ which correspond to msg[1], msg[2] and msg[3], but not msg[4]. This is because a slice starts at the ﬁrst index but ﬁnishes one before the end index. This is consistent with indexing: indexing also starts from zero and goes up to one before the length of the string. We can see this by slicing with the value of len(): >>> len(msg) 11 >>> msg[0:11] ’Hello World’ >>> We can also slice with negative indices the same basic rule of starting from the start index and stopping one before the end index applies; here we stop before the space character: >>> msg[0:-6] ’Hello’ >>> Python provides two shortcuts for commonly used slice values. If the start index is 0 then you can leave it out, and if the end index is the length of the string then you can leave it out: >>> msg[:3] ’Hel’ >>> msg[6:] ’World’ >>> The ﬁrst example above selects the ﬁrst three characters from the string, and the second example selects from the character with index 6, namely ’W’, to the end of the string. January 24, 2008 8 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) 2.3.3 Exercises 1. < Deﬁne a string s = ’colorless’. Write a Python statement that changes this to “colourless” using only the slice and concatenation operations. 2. < Try the slice examples from this section using the interactive interpreter. Then try some more of your own. Guess what the result will be before executing the command. 3. < We can use the slice notation to remove morphological endings on words. For example, ’dogs’[:-1] removes the last character of dogs, leaving dog. Use slice notation to remove the afﬁxes from these words (we’ve inserted a hyphen to indicate the afﬁx boundary, but omit this from your strings): dish-es, run-ning, nation-ality, un-do, pre-heat. 4. < We saw how we can generate an IndexError by indexing beyond the end of a string. Is it possible to construct an index that goes too far to the left, before the start of the string? 5. < We can also specify a “step” size for the slice. The following returns every second character within the slice, in a forward or reverse direction: >>> msg[6:11:2] ’Wrd’ >>> msg[10:5:-2] ’drW’ >>> Experiment with different step values. 6. < What happens if you ask the interpreter to evaluate msg[::-1]? Explain why this is a reasonable result. 2.4 Strings, Sequences, and Sentences We have seen how words like Hello can be stored as a string ’Hello’. Whole sentences can also be stored in strings, and manipulated as before, as we can see here for Chomsky’s famous nonsense sentence: >>> sent = ’colorless green ideas sleep furiously’ >>> sent[16:21] ’ideas’ >>> len(sent) 37 >>> However, it turns out to be a bad idea to treat a sentence as a sequence of its characters, because this makes it too inconvenient to access the words. Instead, we would prefer to represent a sentence as a sequence of its words; as a result, indexing a sentence accesses the words, rather than characters. We will see how to do this now. Bird, Klein & Loper 9 January 24, 2008 2.4. Strings, Sequences, and Sentences 2.4.1 Lists A list is designed to store a sequence of values. A list is similar to a string in many ways except that individual items don’t have to be just characters; they can be arbitrary strings, integers or even other lists. A Python list is represented as a sequence of comma-separated items, delimited by square brackets. Here are some lists: >>> squares = [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] >>> shopping_list = [’juice’, ’muffins’, ’bleach’, ’shampoo’] We can also store sentences and phrases using lists. Let’s create part of Chomsky’s sentence as a list and put it in a variable cgi: >>> cgi = [’colorless’, ’green’, ’ideas’] >>> cgi [’colorless’, ’green’, ’ideas’] >>> Because lists and strings are both kinds of sequence, they can be processed in similar ways; just as strings support len(), indexing and slicing, so do lists. The following example applies these familiar operations to the list cgi: >>> len(cgi) 3 >>> cgi[0] ’colorless’ >>> cgi[-1] ’ideas’ >>> cgi[-5] Traceback (most recent call last): File "<stdin>", line 1, in ? IndexError: list index out of range >>> Here, cgi[-5] generates an error, because the ﬁfth-last item in a three item list would occur before the list started, i.e., it is undeﬁned. We can also slice lists in exactly the same way as strings: >>> cgi[1:3] [’green’, ’ideas’] >>> cgi[-2:] [’green’, ’ideas’] >>> Lists can be concatenated just like strings. Here we will put the resulting list into a new variable chomsky. The original variable cgi is not changed in the process: >>> chomsky = cgi + [’sleep’, ’furiously’] >>> chomsky [’colorless’, ’green’, ’ideas’, ’sleep’, ’furiously’] >>> cgi [’colorless’, ’green’, ’ideas’] >>> January 24, 2008 10 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) Now, lists and strings do not have exactly the same functionality. Lists have the added power that you can change their elements. Let’s imagine that we want to change the 0th element of cgi to ’ colorful’, we can do that by assigning the new value to the index cgi[0]: >>> cgi[0] = ’colorful’ >>> cgi [’colorful’, ’green’, ’ideas’] >>> On the other hand if we try to do that with a string get: changing the 0th character in msg to ’J’ we >>> msg[0] = ’J’ Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: object does not support item assignment >>> This is because strings are immutable you can’t change a string once you have created it. However, lists are mutable, and their contents can be modiﬁed at any time. As a result, lists support a number of operations, or methods, that modify the original value rather than returning a new value. A method is a function that is associated with a particular object. A method is called on the object by giving the object’s name, then a period, then the name of the method, and ﬁnally the parentheses containing any arguments. For example, in the following code we use the sort() and reverse() methods: >>> chomsky.sort() >>> chomsky.reverse() >>> chomsky [’sleep’, ’ideas’, ’green’, ’furiously’, ’colorless’] >>> As you will see, the prompt reappears immediately on the line after chomsky.sort() and chomsky.reverse(). That is because these methods do not produce a new list, but instead modify the original list stored in the variable chomsky. Lists also have an append() method for adding items to the end of the list and an index() method for ﬁnding the index of particular items in the list: >>> chomsky.append(’said’) >>> chomsky.append(’Chomsky’) >>> chomsky [’sleep’, ’ideas’, ’green’, ’furiously’, ’colorless’, ’said’, ’Chomsky’] >>> chomsky.index(’green’) 2 >>> Finally, just as a reminder, you can create lists of any values you like. As you can see in the following example for a lexical entry, the values in a list do not even have to have the same type (though this is usually not a good idea, as we will explain in Section 6.2). >>> bat = [’bat’, [[1, ’n’, ’flying mammal’], [2, ’n’, ’striking instrument’]]] >>> Bird, Klein & Loper 11 January 24, 2008 2.4. Strings, Sequences, and Sentences 2.4.2 Working on Sequences One Item at a Time We have shown you how to create lists, and how to index and manipulate them in various ways. Often it is useful to step through a list and process each item in some way. We do this using a for loop. This is our ﬁrst example of a control structure in Python, a statement that controls how other statements are run: >>> ... ... The The The for num in [1, 2, 3]: print ’The number is’, num number is 1 number is 2 number is 3 The interactive interpreter changes the prompt from >>> to ... after encountering the colon at the end of the ﬁrst line. This prompt indicates that the interpreter is expecting an indented block of code to appear next. However, it is up to you to do the indentation. To ﬁnish the indented block just enter a blank line. The for loop has the general form: for variable in sequence followed by a colon, then an indented block of code. The ﬁrst time through the loop, the variable is assigned to the ﬁrst item in the sequence, i.e. num has the value 1. This program runs the statement print ’The number is’, num for this value of num, before returning to the top of the loop and assigning the second item to the variable. Once all items in the sequence have been processed, the loop ﬁnishes. Now let’s try the same idea with a list of words: >>> >>> ... ... 9 s 5 n 5 s 5 p 9 y chomsky = [’colorless’, ’green’, ’ideas’, ’sleep’, ’furiously’] for word in chomsky: print len(word), word[-1], word colorless green ideas sleep furiously The ﬁrst time through this loop, the variable is assigned the value ’colorless’. This program runs the statement print len(word), word[-1], word for this value, to produce the output line: 9 s colorless. This process is known as iteration. Each iteration of the for loop starts by assigning the next item of the list chomsky to the loop variable word. Then the indented body of the loop is run. Here the body consists of a single command, but in general the body can contain as many lines of code as you want, so long as they are all indented by the same amount. (We recommend that you always use exactly 4 spaces for indentation, and that you never use tabs.) We can run another for loop over the Chomsky nonsense sentence, and calculate the average word length. As you will see, this program uses the len() function in two ways: to count the number of characters in a word, and to count the number of words in a phrase. Note that x += y is shorthand for x = x + y; this idiom allows us to increment the total variable each time the loop is run. >>> total = 0 >>> for word in chomsky: ... total += len(word) ... January 24, 2008 12 Bird, Klein & Loper 2. Programming Fundamentals and Python >>> total / len(chomsky) 6 >>> Introduction to Natural Language Processing (DRAFT) We can also write for loops to iterate over the characters in strings. This print statement ends with a trailing comma, which is how we tell Python not to print a newline at the end. >>> sent = ’colorless green ideas sleep furiously’ >>> for char in sent: ... print char, ... c o l o r l e s s g r e e n i d e a s s l e e p >>> f u r i o u s l y A note of caution: we have now iterated over words and characters, using expressions like for word in sent: and for char in sent:. Remember that, to Python, word and char are meaningless variable names, and we could just as well have written for foo123 in sent:. The interpreter simply iterates over the items in the sequence, quite oblivious to what kind of object they represent, e.g.: >>> for foo123 in ’colorless green ideas sleep furiously’: ... print foo123, ... c o l o r l e s s g r e e n i d e a s s l e e p f u r i o u s l y >>> for foo123 in [’colorless’, ’green’, ’ideas’, ’sleep’, ’furiously’]: ... print foo123, ... colorless green ideas sleep furiously >>> However, you should try to choose ’sensible’ names for loop variables because it will make your code more readable. 2.4.3 String Formatting The output of a program is usually structured to make the information easily digestible by a reader. Instead of running some code and then manually inspecting the contents of a variable, we would like the code to tabulate some output. We already saw this above in the ﬁrst for loop example that used a list of words, where each line of output was similar to 5 p sleep, consisting of a word length, the last character of the word, then the word itself. There are many ways we might want to format such output. For instance, we might want to place the length value in parentheses after the word, and print all the output on a single line: >>> for word in chomsky: ... print word, ’(’, len(word), ’),’, colorless ( 9 ), green ( 5 ), ideas ( 5 ), sleep ( 5 ), furiously ( 9 ), >>> However, this approach has a couple of problems. First, the print statement intermingles variables and punctuation, making it a little difﬁcult to read. Second, the output has spaces around every item that was printed. A cleaner way to produce structured output uses Python’s string formatting expressions. Before diving into clever formatting tricks, however, let’s look at a really simple example. Bird, Klein & Loper 13 January 24, 2008 2.4. Strings, Sequences, and Sentences We are going to use a special symbol, %s, as a placeholder in strings. Once we have a string containing this placeholder, we follow it with a single % and then a value v. Python then returns a new string where v has been slotted in to replace %s: >>> "I want a %s right now" % "coffee" ’I want a coffee right now’ >>> In fact, we can have a number of placeholders, but following the % operator we need to put in a tuple with exactly the same number of values: >>> "%s wants a %s %s" % ("Lee", "sandwich", "for lunch") ’Lee wants a sandwich for lunch’ >>> We can also provide the values for the placeholders indirectly. Here’s an example using a for loop: >>> menu = [’sandwich’, ’spam fritter’, ’pancake’] >>> for snack in menu: ... "Lee wants a %s right now" % snack ... ’Lee wants a sandwich right now’ ’Lee wants a spam fritter right now’ ’Lee wants a pancake right now’ >>> We oversimpliﬁed things when we said that placeholders were of the form %s; in fact, this is a complex object, called a conversion speciﬁer. This has to start with the % character, and ends with conversion character such as s‘ or ‘‘d. The %s speciﬁer tells Python that the corresponding variable is a string (or should be converted into a string), while the %d speciﬁer indicates that the corresponding variable should be converted into a decimal representation. The string containing conversion speciﬁers is called a format string. Picking up on the print example that we opened this section with, here’s how we can use two different kinds of conversion speciﬁer: >>> for word in chomsky: ... print "%s (%d)," % (word, len(word)), colorless (9), green (5), ideas (5), sleep (5), furiously (9), >>> To summarize, string formatting is accomplished with a three-part object having the syntax: format % values. The format section is a string containing format speciﬁers such as %s and %d that Python will replace with the supplied values. The values section of a formatting string is a tuple containing exactly as many items as there are format speciﬁers in the format section. In the case that there is just one item, the parentheses can be left out. (We will discuss Python’s string-formatting expressions in more detail in Section 6.3.2). In the above example, we used a trailing comma to suppress the printing of a newline. Suppose, on the other hand, that we want to introduce some additional newlines in our output. We can accomplish this by inserting the “special” character \n into the print string: January 24, 2008 14 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) >>> for word in chomsky: ... print "Word = %s\nIndex = %s\n***" % (word, chomsky.index(word)) ... Word = colorless Index = 0 * Word = green Index = 1 * Word = ideas Index = 2 * Word = sleep Index = 3 * Word = furiously Index = 4 *** >>> 2.4.4 Converting Between Strings and Lists Often we want to convert between a string containing a space-separated list of words and a list of strings. Let’s ﬁrst consider turning a list into a string. One way of doing this is as follows: >>> s = ’’ >>> for word in chomsky: ... s += ’ ’ + word ... >>> s ’ colorless green ideas sleep furiously’ >>> One drawback of this approach is that we have an unwanted space at the start of s. It is more convenient to use the join() method. We specify the string to be used as the “glue”, followed by a period, followed by the join() function. >>> sent = ’ ’.join(chomsky) >>> sent ’colorless green ideas sleep furiously’ >>> So ’ ’.join(chomsky) means: take all the items in chomsky and concatenate them as one big string, using ’ ’ as a spacer between the items. Now let’s try to reverse the process: that is, we want to convert a string into a list. Again, we could start off with an empty list [] and append() to it within a for loop. But as before, there is a more succinct way of achieving the same goal. This time, we will split the new string sent on whitespace: To consolidate your understanding of joining and splitting strings, let’s try the same thing using a semicolon as the separator: >>> sent = ’;’.join(chomsky) >>> sent ’colorless;green;ideas;sleep;furiously’ Bird, Klein & Loper 15 January 24, 2008 2.4. Strings, Sequences, and Sentences >>> sent.split(’;’) [’colorless’, ’green’, ’ideas’, ’sleep’, ’furiously’] >>> To be honest, many people ﬁnd the notation for join() rather unintuitive. There is another function for converting lists to strings, again called join() which is called directly on the list. It uses whitespace by default as the “glue”. However, we need to explicitly import this function into our code. One way of doing this is as follows: >>> import string >>> string.join(chomsky) ’colorless green ideas sleep furiously’ >>> Here, we imported something called string, and then called the function string.join(). In passing, if we want to use something other than whitespace as “glue”, we just specify this as a second parameter: >>> string.join(chomsky, ’;’) ’colorless;green;ideas;sleep;furiously’ >>> We will see other examples of statements with import later in this chapter. In general, we use import statements when we want to get access to Python code that doesn’t already come as part of core Python. This code will exist somewhere as one or more ﬁles. Each such ﬁle corresponds to a Python module this is a way of grouping together code and data that we regard as reusable. When you write down some Python statements in a ﬁle, you are in effect creating a new Python module. And you can make your code depend on another module by using the import statement. In our example earlier, we imported the module string and then used the join() function from that module. By adding string. to the beginning of join(), we make it clear to the Python interpreter that the deﬁnition of join() is given in the string module. An alternative, and equally valid, approach is to use the from module import identiﬁer statement, as shown in the next example: >>> from string import join >>> join(chomsky) ’colorless green ideas sleep furiously’ >>> In this case, the name join is added to all the other identiﬁer that we have deﬁned in the body of our programme, and we can use it to call a function like any other. Note If you are creating a ﬁle to contain some of your Python code, do not name your ﬁle nltk.py: it may get imported in place of the “real” NLTK package. (When it imports modules, Python ﬁrst looks in the current folder / directory.) 2.4.5 Mini-Review Strings and lists are both kind of sequence. As such, they can both be indexed and sliced: January 24, 2008 16 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) >>> query = ’Who knows?’ >>> beatles = [’john’, ’paul’, ’george’, ’ringo’] >>> query[2] ’o’ >>> beatles[2] ’george’ >>> query[:2] ’Wh’ >>> beatles[:2] [’john’, ’paul’] >>> Similarly, strings can be concatenated and so can lists (though not with each other!): >>> newstring = query + " I don’t" >>> newlist = beatles + [’brian’, ’george’] What’s the difference between strings and lists as far as NLP is concerned? As we will see in Chapter 3, when we open a ﬁle for reading into a Python program, what we get initially is a string, corresponding to the contents of the whole ﬁle. If we try to use a for loop to process the elements of this string, all we can pick out are the individual characters in the string we don’t get to choose the granularity. By contrast, the elements of a list can be as big or small as we like: for example, they could be paragraphs, sentence, phrases, words, characters. So lists have this huge advantage, that we can be really ﬂexible about the elements they contain, and correspondingly ﬂexible about what the downstream processing will act on. So one of the ﬁrst things we are likely to do in a piece of NLP code is convert a string into a list (of strings). Conversely, when we want to write our results to a ﬁle, or to a terminal, we will usually convert them to a string. 2.4.6 Exercises 1. < Using the Python interactive interpreter, experiment with the examples in this section. Think of a sentence and represent it as a list of strings, e.g. [’Hello’, ’world’]. Try the various operations for indexing, slicing and sorting the elements of your list. Extract individual items (strings), and perform some of the string operations on them. 2. < Split sent on some other character, such as ’s’. 3. < We pointed out that when phrase is a list, phrase.reverse() returns a modiﬁed version of phrase rather than a new list. On the other hand, we can use the slice trick mentioned in the exercises for the previous section, [::-1] to create a new reversed list without changing phrase. Show how you can conﬁrm this difference in behavior. 4. < We have seen how to represent a sentence as a list of words, where each word is a sequence of characters. What does phrase1[2][2] do? Why? Experiment with other index values. 5. < Write a for loop to print out the characters of a string, one per line. 6. <.) Bird, Klein & Loper 17 January 24, 2008 2.4. Strings, Sequences, and Sentences 7. < Create a variable words containing a list of words. Experiment with words.sort( ) and sorted(words). What is the difference? 8. < Earlier, we asked you to use a text editor to create a ﬁle called test.py, containing the single line msg = ’Hello World’. If you haven’t already done this (or can’t ﬁnd the ﬁle), go ahead and do it now. Next, start up a new session with the Python interpreter, and enter the expression msg at the prompt. You will get an error from the interpreter. Now, try the following (note that you have to leave off the .py part of the ﬁlename): >>> from test import msg >>> msg This time, Python should return with a value. You can also try import test, in which case Python should be able to evaluate the expression test.msg at the prompt. 9. Ñ Process the list chomsky using a for loop, and store the result in a new list lengths. Hint: begin by assigning the empty list to lengths, using lengths = []. Then each time through the loop, use append() to add another length value to the list. 10. Ñ Deﬁne a variable silly to contain the string: ’newly formed bland ideas are inexpressible in an infuriating way’. (This happens to be the legitimate interpretation that bilingual English-Spanish speakers can assign to Chomsky’s famous phrase, according to Wikipedia). Now write code to perform the following tasks: a) Split silly into a list of strings, one per word, using Python’s split() operation, and save this to a variable called bland. b) Extract the second letter of each word in silly and join them into a string, to get ’eoldrnnnna’. c) Combine the words in bland back into a single string, using join(). Make sure the words in the resulting string are separated with whitespace. d) Print the words of silly in alphabetical order, one per line. 11. Ñ The index() function can be used to look up items in sequences. For example, ’ inexpressible’.index(’e’) tells us the index of the ﬁrst position of the letter e. a) What happens when you look up a substring, e.g. ’inexpressible’. index(’re’)? b) Deﬁne a variable words containing a list of words. Now use words.index () to look up the position of an individual word. c) Deﬁne a variable silly as in the exercise above. Use the index() function in combination with list slicing to build a list phrase consisting of all the words up to (but not including) in in silly. January 24, 2008 18 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) 2.5 Making Decisions So far, our simple programs have been able to manipulate sequences of words, and perform some operation on each one. We applied this to lists consisting of a few words, but the approach works the same for lists of arbitrary size, containing thousands of items. Thus, such programs have some interesting qualities: (i) the ability to work with language, and (ii) the potential to save human effort through automation. Another useful feature of programs is their ability to make decisions on our behalf; this is our focus in this section. 2.5.1 Making Simple Decisions Most programming languages permit us to execute a block of code when a conditional expression, or if statement, is satisﬁed. In the following program, we have created a variable called word containing the string value ’cat’. The if statement then checks whether the condition len(word) < 5 is true. Because the conditional expression is true, the body of the if statement is invoked and the print statement is executed. >>>>> if len(word) < 5: ... print ’word length is less than 5’ ... word length is less than 5 >>> If we change the conditional expression to len(word) >= 5, to check that the length of word is greater than or equal to 5, then the conditional expression will no longer be true, and the body of the if statement will not be run: >>> if len(word) >= 5: ... print ’word length is greater than or equal to 5’ ... >>> The if statement, just like the for statement above is a control structure. An if statement is a control structure because it controls whether the code in the body will be run. You will notice that both if and for have a colon at the end of the line, before the indentation begins. That’s because all Python control structures end with a colon. What if we want to do something when the conditional expression is not true? The answer is to add an else clause to the if statement: >>> if len(word) >= 5: ... print ’word length is greater than or equal to 5’ ... else: ... print ’word length is less than 5’ ... word length is less than 5 >>> Finally, if we want to test multiple conditions in one go, we can use an elif clause that acts like an else and an if combined: Bird, Klein & Loper 19 January 24, 2008 2.5. Making Decisions >>> if len(word) < 3: ... print ’word length is less than three’ ... elif len(word) == 3: ... print ’word length is equal to three’ ... else: ... print ’word length is greater than three’ ... word length is equal to three >>> It’s worth noting that in the condition part of an if statement, a nonempty string or list is evaluated as true, while an empty string or list evaluates as false. >>> mixed = [’cat’, ’’, [’dog’], []] >>> for element in mixed: ... if element: ... print element ... cat [’dog’] That is, we don’t need to say if element is True: in the condition. What’s the difference between using if...elif as opposed to using a couple of if statements in a row? Well, consider the following situation: >>> animals = [’cat’, ’dog’] >>> if ’cat’ in animals: ... print 1 ... elif ’dog’ in animals: ... print 2 ... 1 >>> Since the if clause of the statement is satisﬁed, satisﬁed, but also that the condition of the main if clause was not satisﬁed. 2.5.2 Conditional Expressions Python supports a wide range of operators like < and >= for testing the relationship between values. The full set of these relational operators are shown in Table inequalities. Operator < <= == != > >= Relationship less than less than or equal to equal to (note this is two not one = sign) not equal to greater than greater than or equal to Table 2.1: 20 Bird, Klein & Loper January 24, 2008 2. Programming Fundamentals and Python Conditional Expressions Introduction to Natural Language Processing (DRAFT) Normally we use conditional expressions as part of an if statement. However, we can test these relational operators directly at the prompt: >>> 3 < 5 True >>> 5 < 3 False >>> not 5 < 3 True >>> Here we see that these expressions have Boolean values, namely True or False. not is a Boolean operator, and ﬂips the truth value of Boolean statement. Strings and lists also support conditional operators: >>> word = ’sovereignty’ >>> ’sovereign’ in word True >>> ’gnt’ in word True >>> ’pre’ not in word True >>> ’Hello’ in [’Hello’, ’World’] True >>> ’Hell’ in [’Hello’, ’World’] False >>> Strings also have methods for testing what appears at the beginning and the end of a string (as opposed to just anywhere in the string: >>> word.startswith(’sovereign’) True >>> word.endswith(’ty’) True >>> 2.5.3 Iteration, Items, and if Now it is time to put some of the pieces together. We are going to take the string ’how now brown cow’ and print out all of the words ending in ’ow’. Let’s build the program up in stages. The ﬁrst step is to split the string into a list of words: >>> sentence = ’how now brown cow’ >>> words = sentence.split() >>> words [’how’, ’now’, ’brown’, ’cow’] >>> Next, we need to iterate over the words in the list. Just so we don’t get ahead of ourselves, let’s print each word, one per line: Bird, Klein & Loper 21 January 24, 2008 2.5. Making Decisions >>> for word in words: ... print word ... how now brown cow The next stage is to only print out the words if they end in the string ’ow’. Let’s check that we know how to do this ﬁrst: >>> ’how’.endswith(’ow’) True >>> ’brown’.endswith(’ow’) False >>> Now we are ready to put an if statement inside the for loop. Here is the complete program: >>> sentence = ’how now brown cow’ >>> words = sentence.split() >>> for word in words: ... if word.endswith(’ow’): ... print word ... how now cow >>> As you can see, even with this small amount of Python knowledge it is possible to develop useful programs. The key idea is to develop the program in pieces, testing that each one does what you expect, and then combining them to produce whole programs. This is why the Python interactive interpreter is so invaluable, and why you should get comfortable using it. 2.5.4 A Taster of Data Types Integers, strings and lists are all kinds of data types in Python, and have types int, str and list respectively. In fact, every value in Python has a type. Python’s type() function will tell you what an object’s type is: >>> oddments = [’cat’, ’cat’.index(’a’), ’cat’.split()] >>> for e in oddments: ... type(e) ... <type ’str’> <type ’int’> <type ’list’> >>> The type determines what operations you can perform on the data value. So, for example, we have seen that we can index strings and lists, but we can’t index integers: January 24, 2008 22 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) >>> one = ’cat’ >>> one[0] ’c’ >>> two = [1, 2, 3] >>> two[1] 2 >>> three = 1234 >>> three[2] Traceback (most recent call last): File "<pyshell#95>", line 1, in -toplevelthree[2] TypeError: ’int’ object is unsubscriptable >>> The fact that this is a problem with types is signalled by the class of error, i.e., TypeError; an object being “unscriptable” means we can’t index into it. Similarly, we can concatenate strings with strings, and lists with lists, but we cannot concatenate strings with lists: >>> query = ’Who knows?’ >>> beatles = [’john’, ’paul’, ’george’, ’ringo’] >>> query + beatles Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: cannot concatenate ’str’ and ’list’ objects You may also have noticed that our analogy between operations on strings and numbers at the beginning of this chapter broke down pretty soon: >>> ’Hi’ * 3 ’HiHiHi’ >>> ’Hi’ - ’i’ Traceback (most recent File "<stdin>", line TypeError: unsupported >>> 6 / 2 3 >>> ’Hi’ / 2 Traceback (most recent File "<stdin>", line TypeError: unsupported >>> call last): 1, in <module> operand type(s) for -: ’str’ and ’str’ call last): 1, in <module> operand type(s) for /: ’str’ and ’int’ These error messages are another example of Python telling us that we have got our data types in a muddle. In the ﬁrst case, we are told that the operation of substraction (i.e., -) cannot apply to objects of type str, while in the second, we are told that division cannot take str and int as its two operands. 2.5.5 Exercises 1. < Assign a new value to sentence, namely the string ’she sells sea shells by the sea shore’, then write code to perform the following tasks: Bird, Klein & Loper 23 January 24, 2008 2.6. Getting Organized a) Print all words beginning with ’sh’: b) Print all words longer than 4 characters. c) Generate a new sentence that adds the popular hedge word ’like’ before every word beginning with ’se’. Your result should be a single string. 2. < Write code to abbreviate text by removing all the vowels. Deﬁne sentence to hold any string you like, then initialize a new string result to hold the empty string ’’. Now write a for loop to process the string, one character at a time, and append any non-vowel characters to the result string. 3. < We pointed out that when empty strings and empty lists occur in the condition part of an if clause, they evaluate to false. In this case, they are said to be occuring in a Boolean context. Experiment with different kind of non-Boolean expressions in Boolean contexts, and see whether they evaluate as true or false. 4. < Review conditional expressions, such as ’row’ in ’brown’ and ’row’ in [’ brown’, ’cow’]. a) Deﬁne sent to be the string ’colorless green ideas sleep furiously ’, and use conditional expressions to test for the presence of particular words or substrings. b) Now deﬁne words to be a list of words contained in the sentence, using sent. split(), and use conditional expressions to test for the presence of particular words or substrings. 5. Ñ Write code to convert text into hAck3r, where characters are mapped according to the following table: Input: Output: e 3 i 1 o 0 l \| Table 2.2: s 5 . 5w33t! ate 8 2.6 Getting Organized Strings and lists are a simple way to organize data. In particular, they map from integers to values. We can “look up” a character in a string using an integer, and we can look up a word in a list of words using an integer. These cases are shown in Figure 2.3. However, we need a more ﬂexible way to organize and access our data. Consider the examples in Figure 2.4. In the case of a phone book, we look up an entry using a name, and get back a number. When we type a domain name in a web browser, the computer looks this up to get back an IP address. A word frequency table allows us to look up a word and ﬁnd its frequency in a text collection. In all these cases, we are mapping from names to numbers, rather than the other way round as with indexing into sequences. In general, we would like to be able to map between arbitrary types of information. Table linguistic-objects lists a variety of linguistic objects, along with what they map. January 24, 2008 24 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) Figure 2.3: Sequence Look-up Figure 2.4: Dictionary Look-up Linguistic Object Document Index Thesaurus Dictionary Comparative Wordlist Morph Analyzer to List of pages (where word is found) List of synonyms Entry (part of speech, sense deﬁnitions, etymology) Gloss term Cognates (list of words, one per language) Surface form Morphological analysis (list of component morphemes) Table 2.3: Maps from Word Word sense Headword Linguistic Objects as Mappings from Keys to Values Most often, we are mapping from a string to some structured object. For example, a document index maps from a word (which we can represent as a string), to a list of pages (represented as a list of integers). In this section, we will see how to represent such mappings in Python. 2.6.1 Accessing Data with Data Note A Python dictionary is somewhat like a linguistic dictionary they both give you a systematic means of looking things up, and so there is some potential for confusion. However, we hope that it will usually be clear from the context which kind of dictionary we are talking about. Python provides a dictionary data type that can be used for mapping between arbitrary types. Here we deﬁne pos to be an empty dictionary and then add three entries to it, specifying the partof-speech of some words. We add entries to a dictionary using the familiar square bracket notation: Bird, Klein & Loper 25 January 24, 2008 >>> pos = {} >>> pos[’colorless’] = ’adj’ >>> pos[’furiously’] = ’adv’ >>> pos[’ideas’] = ’n’ >>> So, for example, pos[’colorless’] = ’adj’ says that the look-up value of ’colorless ’ in pos is the string ’adj’. 2.6. Getting Organized >>> pos[’missing’] Traceback (most recent call last): File "<stdin>", line 1, in ? KeyError: ’missing’ >>> This raises an important question. Unlike lists and strings, where we can use len() to work out which integers will be legal indices, how do we work out the legal keys for a dictionary? Fortunately, we can check whether a key exists in a dictionary using the in operator: >>> ’colorless’ in pos True >>> ’missing’ in pos False >>> ’missing’ not in pos True >>> Notice that we can use not in to check if a key is missing. Be careful with the in operator for dictionaries: it only applies to the keys and not their values. If we check for a value, e.g. ’adj’ in pos, the result is False, since ’adj’ is not a key. We can loop over all the entries in a dictionary using a for loop. >>> for word in pos: ... print "%s (%s)" % (word, pos[word]) ... colorless (adj) furiously (adv) ideas (n) >>> We can see what the contents of the dictionary look like by inspecting the variable pos. Note the presence of the colon character to separate each key from its corresponding value: >>> pos {’furiously’: ’adv’, ’ideas’: ’n’, ’colorless’: ’adj’} >>> Here, the contents of the dictionary are shown as key-value pairs. As you can see, the order of the key-value pairs is different from the order in which they were originally entered. This is because dictionaries are not sequences but mappings. The keys in a mapping are not inherently ordered, and any ordering that we might want to impose on the keys exists independently of the mapping. As we shall see later, this gives us a lot of ﬂexibility. We can use the same key-value pair format to create a dictionary: >>> pos = {’furiously’: ’adv’, ’ideas’: ’n’, ’colorless’: ’adj’} >>> Using the dictionary methods keys(), values() and items(), we can access the keys and values as separate lists, and also the key-value pairs: >>> pos.keys() [’colorless’, ’furiously’, ’ideas’] >>> pos.values() January 24, 2008 26 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) [’adj’, ’adv’, ’n’] >>> pos.items() [(’colorless’, ’adj’), (’furiously’, ’adv’), (’ideas’, ’n’)] >>> for (key, val) in pos.items(): ... print "%s ==> %s" % (key, val) ... colorless ==> adj furiously ==> adv ideas ==> n >>> Note that keys are forced to be unique. Suppose we try to use a dictionary to store the fact that the word content is both a noun and a verb: >>> pos[’content’] = ’n’ >>> pos[’content’] = ’v’ >>> pos {’content’: ’v’, ’furiously’: ’adv’, ’ideas’: ’n’, ’colorless’: ’adj’} >>> Initially, pos[’content’] is given the value ’n’, and this is immediately overwritten with the new value ’v’. In other words, there is only one entry for ’content’. If we wanted to store multiple values in that entry, we could use a list, e.g. pos[’content’] = [’n’, ’v’]. 2.6.2 Counting with Dictionaries The values stored in a dictionary can be any kind of object, not just a string the values can even be dictionaries. The most common kind is actually an integer. It turns out that we can use a dictionary to store counters for many kinds of data. For instance, we can have a counter for all the letters of the alphabet; each time we get a certain letter we increment its corresponding counter: >>> phrase = ’colorless green ideas sleep furiously’ >>> count = {} >>> for letter in phrase: ... if letter not in count: ... count[letter] = 0 ... count[letter] += 1 >>> count {’a’: 1, ’ ’: 4, ’c’: 1, ’e’: 6, ’d’: 1, ’g’: 1, ’f’: 1, ’i’: 2, ’l’: 4, ’o’: 3, ’n’: 1, ’p’: 1, ’s’: 5, ’r’: 3, ’u’: 2, ’y’: 1} >>> Observe that in is used here in two different ways: for letter in phrase iterates over every letter, running the body of the for loop. Inside this loop, the conditional expression if letter not in count checks whether the letter is missing from the dictionary. If it is missing, we create a new entry and set its value to zero: count[letter] = 0. Now we are sure that the entry exists, and it may have a zero or non-zero value. We ﬁnish the body of the for loop by incrementing this particular counter using the += assignment operator. Finally, we print the dictionary, to see the letters and their counts. This method of maintaining many counters will ﬁnd many uses, and you will become very familiar with it. To make counting much easier, we can use defaultdict, a special kind of container introduced in Python 2.5. This is also included in NLTK for the beneﬁt of readers who are using Python 2.4, and can be imported as shown below. Bird, Klein & Loper 27 January 24, 2008 2.6. Getting Organized >>> phrase = ’colorless green ideas sleep furiously’ >>> from nltk import defaultdict >>> count = defaultdict(int) >>> for letter in phrase: ... count[letter] += 1 >>> count {’a’: 1, ’ ’: 4, ’c’: 1, ’e’: 6, ’d’: 1, ’g’: 1, ’f’: 1, ’i’: 2, ’l’: 4, ’o’: 3, ’n’: 1, ’p’: 1, ’s’: 5, ’r’: 3, ’u’: 2, ’y’: 1} >>> Note Calling defaultdict(int) creates a special kind of dictionary. When that dictionary is accessed with a non-existent key i.e. the ﬁrst time a particular letter is encountered then int() is called to produce the initial value for this key (i.e. 0). You can test this by running the above code, then typing count[’X’] and seeing that it returns a zero value (and not a KeyError as in the case of normal Python dictionaries). The function defaultdict is very handy and will be used in many places later on. There are other useful ways to display the result, such as sorting alphabetically by the letter: >>> sorted(count.items()) [(’ ’, 4), (’a’, 1), (’c’, 1), (’d’, 1), (’e’, 6), (’f’, 1), ..., ...(’y’, 1)] >>> Note The function sorted() is similar to the sort() method on sequences, but rather than sorting in-place, it produces a new sorted copy of its argument. Moreover, as we will see very soon, sorted() will work on a wider variety of data types, including dictionaries. 2.6.3 Getting Unique Entries Sometimes, we don’t want to count at all, but just want to make a record of the items that we have seen, regardless of repeats. For example, we might want to compile a vocabulary from a document. This is a sorted list of the words that appeared, regardless of frequency. At this stage we have two ways to do this. The ﬁrst uses lists. >>> sentence = "she sells sea shells by the sea shore".split() >>> words = [] >>> for word in sentence: ... if word not in words: ... words.append(word) ... >>> sorted(words) [’by’, ’sea’, ’sells’, ’she’, ’shells’, ’shore’, ’the’] >>> There is a better way to do this task using Python’s set data type. We can convert sentence into a set, using set(sentence): January 24, 2008 28 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) >>> set(sentence) set([’shells’, ’sells’, ’shore’, ’she’, ’sea’, ’the’, ’by’]) >>> The order of items in a set is not signiﬁcant, and they will usually appear in a different order to the one they were entered in. The main point here is that converting a list to a set removes any duplicates. We convert it back into a list, sort it, and print. Here is the complete program: >>> sentence = "she sells sea shells by the sea shore".split() >>> sorted(set(sentence)) [’by’, ’sea’, ’sells’, ’she’, ’shells’, ’shore’, ’the’] Here we have seen that there is sometimes more than one way to solve a problem with a program. In this case, we used three different built-in data types, a list, a dictionary, and a set. The set data type mostly closely modeled our task, so it required the least amount of work. 2.6.4 Scaling Up We can use dictionaries to count word occurrences. For example, the following code uses NLTK’s corpus reader to load Macbeth and count the frequency of each word. Before we can use NLTK we need to tell Python to load it, using the statement import nltk. >>> import nltk >>> count = nltk.defaultdict(int) # initialize a dictionary >>> for word in nltk.corpus.gutenberg.words(’shakespeare-macbeth.txt’): # tokenize Macbeth ... word = word.lower() # normalize to lowercase ... count[word] += 1 # increment the counter ... >>> You will learn more about accessing corpora in Section 3.2.3. For now, you just need to know that gutenberg.words() returns a list of words, in this case from Shakespeare’s play Macbeth, and we are iterating over this list using a for loop. We convert each word to lowercase using the string method word.lower(), and use a dictionary to maintain a set of counters, one per word. Now we can inspect the contents of the dictionary to get counts for particular words: >>> count[’scotland’] 12 >>> count[’the’] 692 >>> 2.6.5 Exercises 1. < Using the Python interpreter in interactive mode, experiment with the examples in this section. Create a dictionary d, and add some entries. What happens if you try to access a non-existent entry, e.g. d[’xyz’]? 2. < Try deleting an element from a dictionary, using the syntax del d[’abc’]. Check that the item was deleted. Bird, Klein & Loper 29 January 24, 2008 2.7. Regular Expressions 3. < Create a dictionary e, to represent a single lexical entry for some word of your choice. Deﬁne keys like headword, part-of-speech, sense, and example, and assign them suitable values. 4. < Create two dictionaries, d1 and d2, and add some entries to each. Now issue the command d1.update(d2). What did this do? What might it be useful for? 5. Ñ Write a program that takes a sentence expressed as a single string, splits it and counts up the words. Get it to print out each word and the word’s frequency, one per line, in alphabetical order. 2.7 Regular Expressions For a moment, imagine that you are editing a large text, and you have strong dislike of repeated occurrences of the word very. How could you ﬁnd all such cases in the text? To be concrete, let’s suppose that we assign the following text to the variable. """ Python’s triple quotes """ are used here since they allow us to break a string across lines. One approach to our task would be to convert the string into a list, and look for adjacent items that are both equal to the string ’very’. We use the range(n) function in this example to create a list of consecutive integers from 0 up to, but not including, n: >>> text = s.split() >>> for n in range(len(text)): ... if text[n] == ’very’ and text[n+1] == ’very’: ... print n, n+1 ... 3 4 4 5 >>> However, such an approach is not very ﬂexible or convenient. In this section, we will present Python’s regular expression module re, which supports powerful search and substitution inside strings. As a gentle introduction, we will start out using a utility function re_show() to illustrate how regular expressions match against substrings. re_show() takes two arguments, a pattern that it is looking for, and a string in which the pattern might occur. >>> import nltk >>> nltk.re_show(’very very’, s) Google Analytics is {very very} very nice (now) ... >>> January 24, 2008 30 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) (We have only displayed the ﬁrst part of s that is returned, since the rest is irrelevant for the moment.) As you can see, re_show places curly braces around the ﬁrst occurrence it has found of the string ’ very very’. So an important part of what re_show is doing is searching for any substring of s that matches the pattern in its ﬁrst argument. Now we might want to modify the example so that re_show highlights cases where there are two or more adjacent sequences of ’very’. To do this, we need to use a regular expression operator, namely ’+’. If s is a string, then s+ means: ’match one or more occurrences of s’. Let’s ﬁrst look at the case where s is a single character, namely the letter ’o’: >>> nltk.re_show(’o+’, s) G{oo}gle Analytics is very very very nice (n{o}w) ... >>> ’o+’ is our ﬁrst proper regular expression. You can think of it as matching an inﬁnite set of strings, namely the set {’o’, ’oo’, ’ooo’, ...}. But we would really like to match sequences of least two ’o’s; for this, we need the regular expression ’oo+’, which matches any string consisting of ’o’ followed by one or more occurrences of o. >>> nltk.re_show(’oo+’, s) G{oo}gle Analytics is very very very nice (now) ... >>> Let’s return to the task of identifying multiple occurrences of ’very’. Some initially plausible candidates won’t do what we want. For example, ’very+’ would match ’veryyy’ (but not ’very very’), since the + scopes over the immediately preceding expression, in this case ’y’. To widen the scope of +, we need to use parentheses, as in ’(very)+’. Will this match ’very very’? No, because we’ve forgotten about the whitespace between the two words; instead, it will match strings like ’veryvery’. However, the following does work: >>> nltk.re_show(’(very\s)+’, s) Google Analytics is {very very very }nice (now) >>> Characters preceded by a \, such as ’\s’, have a special interpretation inside regular expressions; thus, ’\s’ matches a whitespace character. We could have used ’ ’ in our pattern, but ’\s’ is better practice in general. One reason is that the sense of “whitespace” we are using is more general than you might have imagined; it includes not just inter-word spaces, but also tabs and newlines. If you try to inspect the variable s, you might initially get a shock: >>> s "Google Analytics is very very very nice (now)\nBy Jason Hoffman 18 August 06\nGoogle ... >>> You might recall that ’\n’ is a special character that corresponds to a newline in a string. The following example shows how newline is matched by ’\s’. >>>>> nltk.re_show(’very\s’, s2) I’m {very }{very }{very }happy >>> Bird, Klein & Loper 31 January 24, 2008 2.7. Regular Expressions Python’s re.findall(patt, s) function is a useful way to ﬁnd all the substrings in s that are matched by patt. Before illustrating, let’s introduce two further special characters, ’\d’ and ’\w ’: the ﬁrst will match any digit, and the second will match any alphanumeric character. Before we can use re.findall() we have to load Python’s regular expression module, using import re. >>> import re >>> re.findall(’\d\d’, s) [’18’, ’06’, ’10’] >>> re.findall(’\s\w\w\w\s’, s) [’ the ’, ’ the ’, ’ its\n’, ’ the ’, ’ and ’, ’ you ’] >>> As you will see, the second example matches three-letter words. However, this regular expression is not quite what we want. First, the leading and trailing spaces are extraneous. Second, it will fail to match against strings such as ’the San’, where two three-letter words are adjacent. To solve this problem, we can use another special character, namely ’\b’. This is sometimes called a “zero-width” character; it matches against the empty string, but only at the beginning and end of words: >>> re.findall(r’\b\w\w\w\b’, s) [’now’, ’the’, ’the’, ’San’, ’its’, ’the’, ’ago’, ’and’, ’you’] Note This example uses a Python raw string: r’\b\w\w\w\b’. The speciﬁc justiﬁcation here is that in an ordinary string, \b is interpreted as a backspace character. Python will convert it to a backspace in a regular expression unless you use the r preﬁx to create a raw string as shown above. Another use for raw strings is to match strings that include backslashes. Suppose we want to match ’either\or’. In order to create a regular expression, the backslash needs to be escaped, since it is a special character; so we want to pass the pattern \\ to the regular expression interpreter. But to express this as a Python string literal, each backslash must be escaped again, yielding the string ’\\\\’. However, with a raw string, this reduces down to r’\\’. Returning to the case of repeated words, we might want to look for cases involving ’very’ or ’ really’, and for this we use the disjunction operator \|. >>> nltk.re_show(’((very\|really). >>> In addition to the matches just illustrated, the regular expression ’((very\|really)\s)+’ will also match cases where the two disjuncts occur with each other, such as the string ’really very really ’. Let’s now look at how to perform substitutions, using the re.sub() function. In the ﬁrst instance we replace all instances of l with s. Note that this generates a string as output, and doesn’t modify the original string. Then we replace any instances of green with red. January 24, 2008 32 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) >>>>> re.sub(’l’, ’s’, sent) ’cosorsess green ideas sseep furioussy’ >>> re.sub(’green’, ’red’, sent) ’colorless red ideas sleep furiously’ >>> We can also disjoin individual characters using a square bracket notation. For example, [aeiou ] matches any of a, e, i, o, or u, that is, any vowel. The expression [^aeiou] matches any single character that is not a vowel. In the following example, we match sequences consisting of a non-vowel followed by a vowel. >>> nltk.re_show(’[^aeiou][aeiou]’, sent) {co}{lo}r{le}ss g{re}en{ i}{de}as s{le}ep {fu}{ri}ously >>> Using the same regular expression, the function re.findall() returns a list of all the substrings in sent that are matched: >>> re.findall(’[^aeiou][aeiou]’, sent) [’co’, ’lo’, ’le’, ’re’, ’ i’, ’de’, ’le’, ’fu’, ’ri’] >>> 2.7.1 Groupings Returning brieﬂy to our earlier problem with unwanted whitespace around three-letter words, we note that re.findall() behaves slightly differently if we create groups in the regular expression using parentheses; it only returns strings that occur within the groups: >>> re.findall(’\s(\w\w\w)\s’, s) [’the’, ’the’, ’its’, ’the’, ’and’, ’you’] >>> The same device allows us to select only the non-vowel characters that appear before a vowel: >>> re.findall(’([^aeiou])[aeiou]’, sent) [’c’, ’l’, ’l’, ’r’, ’ ’, ’d’, ’l’, ’f’, ’r’] >>> By delimiting a second group in the regular expression, we can even generate pairs (or tuples) that we may then go on and tabulate. >>> re.findall(’([^aeiou])([aeiou])’, sent) [(’c’, ’o’), (’l’, ’o’), (’l’, ’e’), (’r’, ’e’), (’ ’, ’i’), (’d’, ’e’), (’l’, ’e’), (’f’, ’u’), (’r’, ’i’)] >>> Our next example also makes use of groups. One further special character is the so-called wildcard element, ’.’; this has the distinction of matching any single character (except ’\n’). Given the string s3, our task is to pick out login names and email domains: >>> ... ... ... ... s3 = """ <hart@vmd.cso.uiuc.edu> Final editing was done by Martin Ward <Martin.Ward@uk.ac.durham> Michael S. Hart <hart@pobox.com> Prepared by David Price, email <ccx074@coventry.ac.uk>""" Bird, Klein & Loper 33 January 24, 2008 2.7. Regular Expressions The task is made much easier by the fact that all the email addresses in the example are delimited by angle brackets, and we can exploit this feature in our regular expression: >>> re.findall(r’<(.+)@(.+)>’, s3) [(’hart’, ’vmd.cso.uiuc.edu’), (’Martin.Ward’, ’uk.ac.durham’), (’hart’, ’pobox.com’), (’ccx074’, ’coventry.ac.uk’)] >>> Since ’.’ matches any single character, ’.+’ will match any non-empty string of characters, including punctuation symbols such as the period. One question that might occur to you is how do we specify a match against a period? The answer is that we have to place a ’\’ immediately before the ’.’ in order to escape its special interpretation. >>> re.findall(r’(\w+\.)’, s3) [’vmd.’, ’cso.’, ’uiuc.’, ’Martin.’, ’uk.’, ’ac.’, ’S.’, ’pobox.’, ’coventry.’, ’ac.’] >>> Now, let’s suppose that we wanted to match occurrences of both ’Google’ and ’google’ in our sample text. If you have been following up till now, you would reasonably expect that this regular expression with a disjunction would do the trick: ’(G\|g)oogle’. But look what happens when we try this with re.findall(): >>> re.findall(’(G\|g)oogle’, s) [’G’, ’G’, ’G’, ’g’] >>> What is going wrong? We innocently used the parentheses to indicate the scope of the operator ’\| ’, but re.findall() has interpreted them as marking a group. In order to tell re.findall() “don’t try to do anything special with these parentheses”, we need an extra piece of notation: >>> re.findall(’(?:G\|g)oogle’, s) [’Google’, ’Google’, ’Google’, ’google’] >>> Placing ’?:’ immediately after the opening parenthesis makes it explicit that the parentheses are just being used for scoping. 2.7.2 Practice Makes Perfect Regular expressions are very ﬂexible and very powerful. However, they often don’t do what you expect. For this reason, you are strongly encouraged to try out a variety of tasks using re_show() and re .findall() in order to develop your intuitions further; the exercises below should help get you started. We suggest that you build up a regular expression in small pieces, rather than trying to get it completely right ﬁrst time. Here are some operators and sequences that are commonly used in natural language processing. Commonly-used Operators and Sequences Zero or more, e.g. a, [a-z] * + One or more, e.g. a+, [a-z]+ ? Zero or one (i.e. optional), e.g. a?, [a-z]? January 24, 2008 34 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) [..] (..) \b \d \s \w \t \n A set or range of characters, e.g. [aeiou], [a-z0-9] Grouping parentheses, e.g. (the\|a\|an) Word boundary (zero width) Any decimal digit (\D is any non-digit) Any whitespace character (\S is any non-whitespace character) Any alphanumeric character (\W is any non-alphanumeric character The tab character The newline character Table 2.4: 2.7.3 Exercises 1. < Describe the class of strings matched by the following regular expressions. Note that ’ ’ means: match zero or more occurrences of the preceding regular expression. a) [a-zA-Z]+ b) [A-Z][a-z] c) \d+(\.\d+)? d) ([bcdfghjklmnpqrstvwxyz][aeiou][bcdfghjklmnpqrstvwxyz ])* e) \w+\|[^\w\s]+ Test your answers using re_show(). 2. < Write regular expressions to match the following classes of strings: a) A single determiner (assume that a, an, and the are the only determiners). b) An arithmetic expression using integers, addition, and multiplication, such as 23+8. 3. Ñ The above example of extracting (name, domain) pairs from text does not work when there is more than one email address on a line, because the + operator is “greedy” and consumes too much of the input. a) Experiment with input text containing more than one email address per line, such as that shown below. What happens? b) Using re.findall(), write another regular expression to extract email addresses, replacing the period character with a range or negated range, such as [ a-z]+ or [^ >]+. c) Now try to match email addresses by changing the regular expression .+ to its “non-greedy” counterpart, .+? Bird, Klein & Loper 35 January 24, 2008 2.8. Summary >>> ... ... ... ... ... s = """ austen-emma.txt:hart@vmd.cso.uiuc.edu (internet) hart@uiucvmd (bitnet) austen-emma.txt:Internet (72600.2026@compuserve.com); TEL: (212-254-5093) austen-persuasion.txt:Editing by Martin Ward (Martin.Ward@uk.ac.durham) blake-songs.txt:Prepared by David Price, email ccx074@coventry.ac.uk """ 4. Ñ Write code to convert text into Pig Latin. This involves two steps: move any consonant (or consonant cluster) that appears at the start of the word to the end, then append ay, e.g. string ’ ingstray, idle ’ idleay. Pig_Latin 5. Ñ Write code to convert text into hAck3r again, this time using regular expressions and substitution, where e ’ 3, i ’ 1, o ’ 0, l ’ \|, s ’ 5, . ’ 5w33t!, ate ’ 8. Normalize the text to lowercase before converting it. Add more substitutions of your own. Now try to map s to two different values: $ for word-initial s, and 5 for word-internal s. 6. Read the Wikipedia entry on Soundex. Implement this algorithm in Python. 2.8 Summary Text is represented in Python using strings, and we type these with single or double quotes: ’ Hello’, "World". The characters of a string are accessed using indexes, counting from zero: ’Hello World’[ 1] gives the value e. The length of a string is found using len(). Substrings are accessed using slice notation: ’Hello World’[1:5] gives the value ello. If the start index is omitted, the substring begins at the start of the string; if the end index is omitted, the slice continues to the end of the string. Sequences of words are represented in Python using lists of strings: [’colorless’, ’ green’, ’ideas’]. We can use indexing, slicing and the len() function on lists. Strings can be split into lists: ’Hello World’.split() gives [’Hello’, ’World ’]. Lists can be joined into strings: ’/’.join([’Hello’, ’World’]) gives ’Hello/ World’. Lists can be sorted in-place: words.sort(). To produce a separate, sorted copy, use: sorted(words). We process each item in a string or list using a for statement: for word in phrase. dictionary is used to map between arbitrary types of information, such as a string and a number: freq[’cat’] = 12. We create dictionaries using the brace notation: pos = {}, pos = {’furiously’: ’adv’, ’ideas’: ’n’, ’colorless’: ’adj’}. January 24, 2008 36 Bird, Klein & Loper 2. Programming Fundamentals and Python Introduction to Natural Language Processing (DRAFT) Some functions are not available by default, but must be accessed using Python’s import statement. Regular expressions are a powerful and ﬂexible method of specifying patterns. Once we have imported the re module, we can use re.findall() to ﬁnd all substrings in a string that match a pattern, and we can use re.sub() to replace substrings of one sort with another. 2.9 2.9.1 Further Reading Python Two freely available online texts are the following: Josh Cogliati, Non-Programmer’s Tutorial for Python,’s_Tutorial_for_Py Allen B. Downey, Jeffrey Elkner and Chris Meyers, How to Think Like a Computer Scientist: Learning with Python, [Rossum & Jr., 2006] is a tutorial introduction to Python by Guido van Rossum, the inventor of Python and Fred L. Drake, Jr., the ofﬁcial editor of the Python documentation. It is available online at. A more detailed but still introductory text is [Lutz & Ascher, 2003], which covers the essential features of Python, and also provides an overview of the standard libraries. [Beazley, 2006] is a succinct reference book; although not suitable as an introduction to Python, it is an excellent resource for intermediate and advanced programmers. Finally, it is always worth checking the ofﬁcial Python Documentation at. 2.9.2 Regular Expressions There are many references for regular expressions, both practical and theoretical. [Friedl, 2002] is a comprehensive and detailed manual in using regular expressions, covering their syntax in most major programming languages, including Python. For an introductory tutorial to using regular expressions in Python with the re module, see A. M. Kuchling, Regular Expression HOWTO,. Chapter 3 of [Mertz, 2003] provides a more extended tutorial on Python’s facilities for text processing with regular expressions. is a useful online resource, providing a tutorial and references to tools and other sources of information. 2.9.3!), Bird, Klein & Loper 37 January 24, 2008 2.9. Further Reading 38 Bird, Klein & Loper Chapter 3 Words: The Building Blocks of Language 3.1 Introduction Language can be divided up into pieces of varying sizes, ranging from morphemes to paragraphs. In this chapter we will focus on words, the most fundamental level for NLP. Just what are words, and how should we represent them in a machine? These questions may seem trivial, but we’ll see that there are some important issues involved in deﬁning and representing words. Once we’ve tackled them, we’re in a good position to do further processing, such as ﬁnd related words and analyze the style of a text (this chapter), to categorize words (Chapter 4), to group them into phrases (Chapter 7 and Part II), and to do a variety of language engineering tasks (Chapter 5). In the following sections, we will explore the division of text into words; the distinction between types and tokens; sources of text data including ﬁles, the web, and linguistic corpora; accessing these sources using Python and NLTK; stemming and normalization; the WordNet lexical database; and a variety of useful programming tasks involving words. Note From this chapter onwards, our program samples will assume you begin your interactive session or your program with: import nltk, re, pprint 3.2 Tokens, Types and Texts In Chapter 1, we showed how a string could be split into a list of words. Once we have derived a list, the len() function will count the number of words it contains: >>>>> words = sentence.split() >>> len(words) 13 This process of segmenting a string of characters into words is known as tokenization. Tokenization is a prelude to pretty much everything else we might want to do in NLP, since it tells our processing software what our basic units are. We will discuss tokenization in more detail shortly. We also pointed out that we could compile a list of the unique vocabulary items in a string by using set() to eliminate duplicates: 1 3.2. Tokens, Types and Texts >>> len(set(words)) 10 So if we ask how many words there are in sentence, we get different answers depending on whether we count duplicates. Clearly we are using different senses of “word” here. To help distinguish between them, let’s introduce two terms: token and type. A word token is an individual occurrence of a word in a concrete context; it exists in time and space. A word type is a more abstract; it’s what we’re talking about when we say that the three occurrences of the in sentence are “the same word.” Something similar to a type-token distinction is reﬂected in the following snippet of Python: >>> words[2] ’the’ >>> words[2] == words[8] True >>> words[2] is words[8] False >>> words[2] is words[2] True The operator == tests whether two expressions are equal, and in this case, it is testing for stringidentity. This is the notion of identity that was assumed by our use of set() above. By contrast, the is operator tests whether two objects are stored in the same location of memory, and is therefore analogous to token-identity. When we used split() to turn a string into a list of words, our tokenization method was to say that any strings that are delimited by whitespace count as a word token. But this simple approach doesn’t always give the desired results. Also, testing string-identity isn’t a very useful criterion for assigning tokens to types. We therefore need to address two questions in more detail: Tokenization: Which substrings of the original text should be treated as word tokens? Type deﬁnition: How do we decide whether two tokens have the same type? To see the problems with our ﬁrst stab at deﬁning tokens and types in sentence, let’s look at the actual tokens we found: >>> set(words) set([’and’, ’this’, ’record’, ’This’, ’of’, ’is’, ’--’, ’time.’, ’time’, ’the’]) Observe that ’time’ and ’time.’ are incorrectly treated as distinct types since the trailing period has been bundled with the rest of the word. Although ’--’ is some kind of token, it’s not a word token. Additionally, ’This’ and ’this’ are incorrectly distinguished from each other, because of a difference in capitalization that should be ignored. If we turn to languages other than English, tokenizing text is even more challenging. In Chinese text there is no visual representation of word boundaries. Consider the following three-character string: 1ýº (in pinyin plus tones: ai4 “love” (verb), guo3 “country”, ren2 “person”). This could either be segmented as [1ý]º, “country-loving person” or as 1[ýº], “love country-person.” The terms token and type can also be applied to other linguistic entities. For example, a sentence token is an individual occurrence of a sentence; but a sentence type is an abstract sentence, without context. If I say the same sentence twice, I have uttered two sentence tokens but only used one sentence type. When the kind of token or type is obvious from context, we will simply use the terms token and type. To summarize, we cannot just say that two word tokens have the same type if they are the same string of characters. We need to consider a variety of factors in determining what counts as the same word, and we need to be careful in how we identify tokens in the ﬁrst place. January 24, 2008 2 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) Up till now, we have relied on getting our source texts by deﬁning a string in a fragment of Python code. However, this is impractical for all but the simplest of texts, and makes it hard to present realistic examples. So how do we get larger chunks of text into our programs? In the rest of this section, we will see how to extract text from ﬁles, from the web, and from the corpora distributed with NLTK. 3.2.1 Extracting Text from Files It is easy to access local ﬁles in Python. As an exercise, create a ﬁle called corpus.txt using a text editor, and enter the following text: Hello World! This is a test file. Be sure to save the ﬁle as plain text. You also need to make sure that you have saved the ﬁle in the same directory or folder in which you are running the Python interactive interpreter. Note If you are using IDLE, you can easily create this ﬁle by selecting the New Window command in the File menu, typing the required text into this window, and then saving the ﬁle as corpus.txt in the ﬁrst directory that IDLE offers in the pop-up dialogue box. The next step is to open a ﬁle using the built-in function open() which takes two arguments, the name of the ﬁle, here corpus.txt, and the mode to open the ﬁle with (’r’ means to open the ﬁle for reading, and ’U’ stands for “Universal”, which lets us ignore the different conventions used for marking newlines). >>> f = open(’corpus.txt’, ’rU’) Note If the interpreter cannot ﬁnd your ﬁle, it will give an error like this: >>> f = open(’corpus.txt’, ’rU’) Traceback (most recent call last): File "<pyshell#7>", line 1, in -toplevelf = open(’corpus.txt’, ’rU’) IOError: [Errno 2] No such file or directory: ’corpus.txt’ To check that the ﬁle that you are trying to open is really in the right directory, use IDLE’s Open command in the File menu; this will display a list of all the ﬁles in the directory where IDLE is running. An alternative is to examine the current directory from within Python: >>> import os >>> os.listdir(’.’) There are several methods for reading the ﬁle. The following uses the method read() on the ﬁle object f; this reads the entire contents of a ﬁle into a string. >>> f.read() ’Hello World!\nThis is a test file.\n’ Bird, Klein & Loper 3 January 24, 2008 3.2. Tokens, Types and Texts Recall that the ’\n’ characters are newlines; this is equivalent to pressing Enter on a keyboard and starting a new line. Note that we can open and read a ﬁle in one step: >>> text = open(’corpus.txt’, ’rU’).read() We can also read a ﬁle one line at a time using the for loop construct: >>> f = open(’corpus.txt’, ’rU’) >>> for line in f: ... print line[:-1] Hello world! This is a test file. Here we use the slice [:-1] to remove the newline character at the end of the input line. 3.2.2 Extracting Text from the Web Opening a web page is not much different to opening a ﬁle, except that we use urlopen(): >>> from urllib import urlopen >>> page = urlopen("").read() >>> print page[:60] <!doctype html public "-//W3C//DTD HTML 4.0 Transitional//EN Web pages are usually in HTML format. To extract the text, we need to strip out the HTML markup, i.e. remove all material enclosed in angle brackets. Let’s digress brieﬂy to consider how to carry out this task using regular expressions. Our ﬁrst attempt might look as follows: >>> line = ’<title>BBC NEWS \| News Front Page</title>’ >>> new = re.sub(r’<.>’, ’’, line) So the regular expression ’<.>’ is intended to match a pair of left and right angle brackets, with a string of any characters intervening. However, look at what the result is: >>> new ’’. January 24, 2008 4 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) You will probably ﬁnd sufﬁciently common task that NLTK provides a helper function nltk.clean_html(), which takes an HTML string and returns text. 3.2.3 Extracting Text from NLTK Corpora NLTK is distributed with several corpora and corpus samples and many are supported by the corpus package. Here we use a selection of texts from the Project Gutenberg electronic text archive, and list the ﬁles The Brown Corpus was the ﬁrst million-word, part-of-speech tagged electronic corpus of English, created in 1961 at Brown University. Each of the sections a through r represents a different genre, as shown in Table 3.1. Sec a d g k m Genre Press: Reportage Religion Belles-Lettres Fiction: General Fiction: Science Sec b e h k n Genre Press: Editorial Skill and Hobbies Government Fiction: General Fiction: Adventure Sec c f j l p Genre Press: Reviews Popular Lore Learned Fiction: Mystery Fiction: Romance Bird, Klein & Loper 5 January 24, 2008 3.2. Tokens, Types and Texts Sec r Genre Humor Sec Genre Sec Genre Table 3.1: Before concluding this section, we return to the original topic of distinguishing tokens and types. Now that we can access substantial quantities of text, we will give a preview of the interesting computations we will be learning how to do (without yet explaining all the details). Listing 3.1 computes vocabulary growth curves for US Presidents, shown in Figure 3.1 (a color ﬁgure in the online version). These curves show the number of word types seen after n word tokens have been read. Note Listing 3.1 uses the PyLab package which supports sophisticated plotting functions with a MATLAB-style interface. For more information about this package please see. The listing also uses the yield statement, which will be explained in Chapter 6. 3.2.4 Exercises 1. < Create a small text ﬁle, and write a program to read it and print it with a line number at the start of each line. (Make sure you don’t introduce an extra blank line between each line.) 2. < Use the corpus module to read austen-persuasion.txt. How many word tokens does this book have? How many word types? January 24, 2008 6 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) Listing 3.1 Vocabulary Growth in State-of-the-Union Addresses def vocab_growth(text):() Figure 3.1: Vocabulary Growth in State-of-the-Union Addresses Bird, Klein & Loper 7 January 24, 2008 3.3. Text Processing with Unicode 3. < Use the Brown corpus reader nltk.corpus.brown.words() or the Web text corpus reader nltk.corpus.webtext.words() to access some sample text in two different genres. 4. < Use the Brown corpus reader nltk.corpus.brown.sents() to ﬁnd sentenceinitial examples of the word however. Check whether these conform to Strunk and White’s prohibition against sentence-initial however used to mean “although”. 5. < Read in the texts of the State of the Union addresses, using the state_union corpus reader. Count occurrences of men, women, and people in each document. What has happened to the usage of these words over time? 6. Ñ Write code to read a ﬁle and print the lines in reverse order, so that the last line is listed ﬁrst. 7. Ñ? 8. Ñ Write code to access a favorite webpage and extract some text from it. For example, access a weather site and extract the forecast top temperature for your town or city today. 9. Ñ Examine the results of processing the URL using the regular expressions suggested above. You will see that there is still a fair amount of nontextual data there, particularly Javascript commands. You may also ﬁnd that sentence breaks have not been properly preserved. Deﬁne further regular expressions that improve the extraction of text from this web page. 10. Ñ Take a copy of the over three different days, say at two-day intervals. This should give you three different ﬁles, bbc1.txt, bbc2.txt and bbc3.txt, each corresponding to a different snapshot of world events. Collect the 100 most frequent word tokens for each ﬁle. What can you tell from the changes in frequency? 11. Ñ Deﬁne a function ghits() that takes a word as its argument and builds a Google query string of the form. Strip the HTML markup and normalize whitespace. Search for a substring of the form Results 1 10 of about, followed by some number n, and extract n. Convert this to an integer and return it. 12. Ñ Try running the various chatbots included with NLTK, using nltk.chat.demo(). How intelligent are these programs? Take a look at the program code and see if you can discover how it works. You can ﬁnd the code online at: chat/. 3.3 Text Processing with Unicode Our programs will often need to deal with different languages, and different character sets. The concept of “plain text” is a ﬁction. If you live in the English-speaking world you probably use ASCII, possibly January 24, 2008 8 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) without realizing it. If you live in Europe you might use one of the extended Latin character sets, containing such characters as “ø” for Danish and Norwegian, “Q” for Hungarian, “ñ” for Spanish and Breton, and “H” for Czech and Slovak. In this section, we will give an overview of how to use Unicode for processing texts that use non-ASCII character sets. 3.3.1 What is Unicode? Unicode supports over a million characters. Each of these characters is assigned a number, called a code point. In Python, code points are written in the form \uXXXX, where XXXX is the number in 4-digit hexadecimal form. Within a program, Unicode code points can be manipulated directly, but when Unicode characters are stored in ﬁles ﬁles will be in a particular encoding, so we need some mechanism for translating it into Unicode translation into Unicode is called decoding. Conversely, to write out Unicode to a ﬁle or a terminal, we ﬁrst need to translate it into a suitable encoding this translation out of Unicode is called encoding. The following diagram illustrates. From a Unicode perspective, characters are abstract entities which can be realized as one or more glyphs. Only glyphs can appear on a screen or be printed on paper. A font is a mapping from characters to glyphs. 3.3.2 Extracting encoded text from ﬁles Let’s assume that we have a small text ﬁle, ﬁle ﬁle being read or written. So let’s import the codecs module, and call it with the encoding ’latin2’ to open our Polish ﬁle as Unicode. >>> import codecs >>> f = codecs.open(path, encoding=’latin2’) Bird, Klein & Loper 9 January 24, 2008 3.3. Text Processing with Unicode For a list of encoding parameters allowed by codecs, see. Text read from the ﬁle object f will be returned in Unicode. As we pointed out earlier, in order to view this text on a terminal, we need to encode it, using a suitable encoding. The Python-speciﬁc encoding unicode_escape is a dummy encoding that converts all non-ASCII characters into their \uXXXX representations. Code points above the ASCII 0-127 range but below 256 are represented in the two-digit form \xXX. >>> ﬁrst line above illustrates a Unicode escape string, namely preceded by the \u escape string, namely \u0144 . The relevant Unicode character will be dislayed on the screen as the glyph D. In the third line of the preceding example, we see \xf3, which corresponds to the glyph ó, and is within the 128-255 range. In Python, a Unicode string literal can be speciﬁed by preceding an ordinary string literal with a u, as in u’hello’. Arbitrary Unicode characters are deﬁned using the \uXXXX escape sequence inside a Unicode string literal. We ﬁnd the integer ordinal of a character using ord(). For example: >>> ord(’a’) 97 The hexadecimal 4 digit notation for 97 is 0061, so we can deﬁne a Unicode string literal with the appropriate escape sequence: >>> a = u’\u0061’ >>> a u’a’ >>> print a a Notice that the Python print statement is assuming a default encoding of the Unicode character, namely ASCII. However, D is outside the ASCII range, so cannot be printed unless we specify an encoding. In the following example, we have speciﬁed that print should use the repr() of the string, which outputs the UTF-8 escape sequences (of the form \xXX) rather than trying to render the glyphs. >>> nacute = u’\u0144’ >>> nacute u’\u0144’ >>> nacute_utf = nacute.encode(’utf8’) >>> print repr(nacute_utf) ’\xc5\x84’ January 24, 2008 10 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) If your operating system and locale are set up to render UTF-8 encoded characters, you ought to be able to give the Python command print nacute_utf and see D., preﬁx U+00f3 LATIN SMALL LETTER O WITH ACUTE [ U+015b LATIN SMALL LETTER S WITH ACUTE Z U+015a LATIN CAPITAL LETTER S WITH ACUTE U+0105 LATIN SMALL LETTER A WITH OGONEK B Bird, Klein & Loper 11 January 24, 2008 3.3. Text Processing with Unicode >>>’] 3.3.3 Using your local encoding in Python If you are used to working with characters in a particular local encoding, you probably want to be able to use your standard methods for inputting and editing strings in a Python ﬁle. In order to do this, you need to include the string ’# -- coding: <coding> --’ as the ﬁrst or second line of your ﬁle. Note that <coding> has to be a string like ’latin-1’, ’big5’ or ’utf-8’. Note If you are using Emacs as your editor, the coding speciﬁcation will also be interpreted as a speciﬁcation of the editor’s coding for the ﬁle. Not all of the valid Python names for codings are accepted by Emacs. The following screenshot illustrates the use of UTF-8 encoded string literals within the IDLE editor: Note The above example requires that an appropriate font is set in IDLE’s preferences. In this case, we chose Courier CE. The above example also illustrates how regular expressions can use encoded strings. 3.3.4 Chinese and XML Codecs for processing Chinese text have been incorporated into Python (since version 2.4). January 24, 2008 12 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) >>>: ó+åº5. We can also read in the contents of an XML ﬁle using the etree package (at least, if the ﬁle is encoded as UTF-8 as of writing, there seems to be a problem reading GB2312-encoded ﬁles’ 3.3.5 Exercises 1. < Using the Python interactive interpreter, experiment with applying some of the techniques for list and string processing to Unicode strings. 3.4 Tokenization and Normalization Tokenization, as we saw, is the task of extracting a sequence of elementary tokens that constitute a piece of language data. In our ﬁrst. 3.4.1 Tokenization with Regular Expressions The function nltk.tokenize.regexp_tokenize() takes a text string and a regular expression, and returns the list of substrings that match the regular expression. To deﬁne a tokenizer that includes punctuation as separate tokens, we could do the following: Bird, Klein & Loper 13 January 24, 2008 3.4. Tokenization and Normalization >>> text = ’’’Hello. Isn’t this fun?’’’ >>> pattern = r’\w+\|[^\w\s]+’ >>> nltk.tokenize.regexp_tokenize(text, pattern) [’Hello’, ’.’, ’Isn’, "’", ’t’, ’this’, ’fun’, ’?’] ﬂag” deﬁne, deﬁned on strings: text.split().) 3.4.2 Lemmatization and Normalization Earlier we talked about counting word tokens, and completely ignored the rest of the sentence in which these tokens appeared. Thus, for an example like I saw the saw, we would have treated both saw tokens as instances of the same type. However, one is a form of the verb see, and the other is the name of a cutting instrument. How do we know that these two forms of saw will occur immediately after determiners such as the. Distinct words that have the same written form are called homographs. We can distinguish homographs with the help of context; often the previous word sufﬁces. We will explore this idea of context brieﬂy, before addressing the main topic of this section. January 24, 2008 14 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) As a ﬁrst approximation to discovering the distribution of a word, we can look at all the bigrams it occurs in. A bigram is simply a pair of words. For example, in the sentence She sells sea shells by the sea shore, the bigrams are She sells, sells sea, sea shells, shells by, by the, the sea, sea shore. Let’s consider all bigrams from the Brown Corpus that have the word often as ﬁrst element. Here is a small selection, ordered by their counts: often often often often often often often often often often often often often often often often , a in than the been do called appear were appeared are did is appears call 16 10 8 7 7 6 5 4 3 3 2 2 2 2 1 1 In the topmost entry, we see that often is frequently followed by a comma. This suggests that often is common at the end of phrases. We also see that often precedes verbs, presumably as an adverbial modiﬁer. We might conclude that when saw appears in the context often saw, then saw is being used as a verb. You will also see that this list includes different grammatical forms of the same verb. We can form separate groups consisting of appear ~ appears ~ appeared; call ~ called; do ~ did; and been ~ were ~ are ~ is. It is common in linguistics to say that two forms such as appear and appeared belong to a more abstract notion of a word called a lexeme; by contrast, appeared and called belong to different lexemes. You can think of a lexeme as corresponding to an entry in a dictionary, and a lemma as the headword for that entry. By convention, small capitals are used when referring to a lexeme or lemma: APPEAR . Although appeared and called belong to different lexemes, they do have something in common: they are both past tense forms. This is signaled by the segment -ed, which we call a morphological sufﬁx. We also say that such morphologically complex forms are inﬂected. If we strip off the sufﬁx, we get something called the stem, namely appear and call respectively. While appeared, appears and appearing are all morphologically inﬂected, appear lacks any morphological inﬂection and is therefore termed the base form. In English, the base form is conventionally used as the lemma for a word. Our notion of context would be more compact if we could group different forms of the various verbs into their lemmas; then we could study which verb lexemes are typically modiﬁed by a particular adverb. Lemmatization the process of mapping words to their lemmas would yield the following picture of the distribution of often. Here, the counts for often appear (3), often appeared (2) and often appears (1) are combined into a single line. often often often often , a be in 16 10 13 8 Bird, Klein & Loper 15 January 24, 2008 3.4. Tokenization and Normalization often often often often often than the do appear call 7 7 7 6 5 Lemmatization is a rather sophisticated process that uses rules for the regular word patterns, and table look-up for the irregular patterns. Within NLTK, we can use off-the-shelf stemmers, such as the Porter Stemmer, the Lancaster Stemmer,’ A ﬁnal issue for normalization is the presence of contractions, such as didn’t. If we are analyzing the meaning of a sentence, it would probably be more useful to normalize this form to two separate forms: did and n’t (or not). 3.4.3 Transforming Lists Lemmatization and normalization involve applying the same operation to each word token in a text. List comprehensions are a convenient Python construct for doing this. Here we lowercase each word: >>> sent = [’The’, ’dog’, ’gave’, ’John’, ’the’, ’newspaper’] >>> [word.lower() for word in sent] [’the’, ’dog’, ’gave’, ’john’, ’the’, ’newspaper’]’] January 24, 2008 16 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) Now we can eliminate repeats using set(), by passing the list comprehension as an argument. We can actually leave out the square brackets, as will be explained further in Chapter 10. >>> set(stemmer.stem(verb) for verb in verbs) set([’call’, ’appear’]) This syntax might be reminiscent of the notation used for building sets, e.g. {(x,y) \| x2 + y2 = 1}. (We will return to sets later in Section 10.6). Just as this set deﬁnition’), (’‘‘’, ’‘‘’), (’no’, ’no’), (’evidence’, ’evid’), ("’’", "’’"), (’that’, ’that’), (’any’, ’ani’), (’irregularities’, ’irregular’), (’took’, ’took’), (’place’, ’place’), (’.’, ’.’)] 3.4.4 Exercises 1. < Regular expression tokenizers: Save some text into a ﬁle corpus.txt. Deﬁne a function load(f) that reads from the ﬁle named in its sole argument, and returns a string containing the text of the ﬁle. a) Use nltk.tokenize.regexp_tokenize() to create a tokenizer that tokenizes the various kinds of punctuation in this text. Use a single regular expression, with inline comments using the re.VERBOSE ﬂag. b) Use nltk.tokenize.regexp_tokenize() to create a tokenizer that tokenizes the following kinds of expression: monetary amounts; dates; names of people and companies. 2. < Rewrite the following loop as a list comprehension: >>> sent = [’The’, ’dog’, ’gave’, ’John’, ’the’, ’newspaper’] >>> result = [] Bird, Klein & Loper 17 January 24, 2008 3.4. Tokenization and Normalization >>> for word in sent: ... word_len = (word, len(word)) ... result.append(word_len) >>> result [(’The’, 3), (’dog’, 3), (’gave’, 4), (’John’, 4), (’the’, 3), (’newspaper’, 9) 3. Ñ Use the Porter Stemmer to normalize some tokenized text, calling the stemmer on each word. Do the same thing with the Lancaster Stemmer and see if you observe any differences. 4. Ñ ﬁve three, plus or minus ﬁfteen percent”? Or should we say that it’s not a “real” word at all, since it wouldn’t appear in any dictionary? Discuss these different possibilities. Can you think of application domains that motivate at least two of these answers? 5. Ñ Readability measures are used to score the reading difﬁculty of a text, for the purposes of selecting texts of appropriate difﬁculty for language learners. Let us deﬁne ¼w to be the average number of letters per word, and ¼ s to be the average number of words per sentence, in a given text. The Automated Readability Index (ARI) of the text is deﬁned to be: 4.71 ‘‘ \|mu\|\ :subscript:‘w‘ ‘‘+ 0.5 * ‘‘ \|mu\|\ :subscript:‘s‘ ‘‘-. 6. Obtain raw texts from two or more genres and compute their respective reading difﬁculty scores as in the previous exercise. E.g. compare ABC Rural News and ABC Science News (nltk.corpus.abc). Use nltk.tokenize.punkt() to perform sentence segmentation.’] 7. January 24, 2008 18 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) 3.5) ` >>> sec_a = nltk.corpus.brown.words(categories=’a’) >>> for token in sec_a: ... counts[token] += 1 a >>> for token in sorted(counts)[:5]: b ... print counts[token], token 38 ! 5 $1 2 $1,000 1 $1,000,000,000 3 $1,500 In line ` we initialize the dictionary. Then for each word in each sentence we increment a counter (line a). To view the contents of the dictionary, we can iterate over its keys and print each entry (here just for the ﬁrst 5 entries, line b). 3.5.1 Frequency Distributions This style of output and our counts object are just different forms of the same abstract structure a collection of items and their frequencies known as a frequency distribution. deﬁned on NLTK frequency distributions are shown in Table 3.2. Name Count Frequency N Samples Max Sample fd[’the’] fd.freq(’the’) fd.N() list(fd) fd.max() Table 3.2: Description number of times a given sample occurred frequency of a given sample number of samples list of distinct samples recorded (also fd.keys()) sample with the greatest number of outcomes Frequency Distribution Module Bird, Klein & Loper 19 January 24, 2008 3.5. Counting Words: Several Interesting Applications This output isn’t very interesting. Perhaps it would be more informative to list the most frequent word tokens ﬁrst. Now a FreqDist object is just a kind of dictionary, so we can easily get its key-value pairs and sort them by decreasing values, as follows: >>> from operator import itemgetter >>> sorted_word_counts = sorted(fd.items(), key=itemgetter(1), reverse=True) >>> [token for (token, freq) in sorted_word_counts[:20]] [’the’, ’,’, ’.’, ’of’, ’and’, ’to’, ’a’, ’in’, ’for’, ’The’, ’that’, ’‘‘’, ’is’, ’was’, "’’", ’on’, ’at’, ’with’, ’be’, ’by’] ` Note the arguments of the sorted() function (line `): itemgetter(1) returns a function that can be called on any sequence object to return the item at position 1; reverse=True performs the sort in reverse order. Together, these ensure that the word with the highest frequency is listed ﬁrst. This reversed sort by frequency is such a common requirement that it is built into the FreqDist object. Listing 3.2 demonstrates this, and also prints rank and cumulative frequency. Unfortunately the output in Listing 3.2 is surprisingly dull. A mere handful of tokens account for a third of the text. They just represent the plumbing of English text, and are completely uninformative! How can we ﬁnd words that are more indicative of a text? As we will see in the exercises for this section, we can modify the program to discard the non-content words. In the next section we see another approach. 3.5.2 Stylistics Stylistics is a broad term covering literary genres and varieties of language use. Here we will look at a document collection that is categorized by genre, and try to learn something about the patterns of word usage. For example, Table 3.3 was constructed by counting the number of times various modal words appear in different sections of the corpus: Genre can could may might must will 259 13 16 387 43 64 skill and hobbies 273 59 130 22 83 humor 17 33 8 8 9 ﬁction: science 16 49 4 12 8 press: reportage 94 86 66 36 50 ﬁction: romance 79 195 11 51 46 religion 84 59 79 12 54 Table 3.3: Use of Modals in Brown Corpus, by Genre Observe that the most frequent modal in the reportage genre is will, suggesting a focus on the future, while the most frequent modal in the romance genre is could, suggesting a focus on possibilities. We can also measure the lexical diversity of a genre, by calculating the ratio of word types and word tokens, as shown in Table 3.4. Genres with lower diversity have a higher number of tokens per type, thus we see that humorous prose is almost twice as lexically diverse as romance prose. Genre skill and hobbies Token Count 82345 Type Count 11935 Ratio 6.9 January 24, 2008 20 Bird, Klein & Loper 3. Words: The Building Blocks of Language Genre Introduction to Natural Language Processing (DRAFT) Token Count Type Count Ratio 4.3 4.5 7.0 8.3 6.2 Brown humor 21695 5017 ﬁction: science 14470 3233 press: reportage 100554 14394 ﬁction: romance 70022 8452 religion 39399 6373 Table 3.4: Lexical Diversity of Various Genres in the Corpus We can carry out a variety of interesting explorations simply by counting words. In fact, the ﬁeld of Corpus Linguistics focuses heavily on creating and interpreting such tables of word counts. 3.5.3 Aside: Deﬁning efﬁcient (and reliable) to localize this work inside a function. A function is a programming construct that can be called with one or more inputs and which returns an output. We deﬁne 3.3 takes a singular noun as input, and generates a plural form as output. (There is much more to be said about ways of deﬁning functions, but we will defer this until Section 6.4.) 3.5.4 3.2: Lexical Dispersion Plot for the Main Characters in Sense and Sensibility As you can see, Elinor and Marianne appear rather uniformly throughout the text, while Edward and Willoughby tend to appear separately. Here is the program that generated the above plot. Bird, Klein & Loper 21 January 24, 2008 3.5. Counting Words: Several Interesting Applications Listing 3.2% ‘‘ 13 29% is 14 30% was 15 31% ’’ 16 31% on 17 32% at 18 32% with 19 33% be 20 33% by Listing 3.3’ January 24, 2008 22 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) 3.5.5 Comparing Word Lengths in Different Languages We can use a frequency distribution to examine the distribution of word lengths in a corpus. For each word, we ﬁnd 3.4 we look at it on a larger scale using the Universal Declaration of Human Rights corpus, which has text samples from over 300 languages. (Note that the names of the ﬁles in this corpus include information about character encoding; here we will use texts in ISO Latin-1.) The output is shown in Figure 3.3 (a color ﬁgure in the online version). Listing 3.4() 3.5.6 Generating Random Text with Style We have used frequency distributions to count the number of occurrences of each word in a text. Here we will generalize this idea to look at the distribution of words in a given context. A conditional frequency distribution is a collection of frequency distributions, each one for a different condition. Here the condition will be the preceding word. In Listing 3.5, we’ve deﬁned a function train_model() that uses ConditionalFreqDist () to count words as they appear relative to the context deﬁned by the preceding word (stored in Bird, Klein & Loper 23 January 24, 2008 3.5. Counting Words: Several Interesting Applications Figure 3.3: Cumulative Word Length Distributions for Several Languages. 3.5.7 Collocations Collocations are pairs of content words that occur together more often than one would expect if the words of a document were scattered randomly. We can ﬁnd collocations by counting how many times a pair of words w1 , w2 occurs together, compared to the overall counts of these words (this program uses a heuristic related to the mutual information measure,) In Listing 3.6 we try this for the ﬁles in the webtext corpus. 3.5.8 Exercises 1. < Pick a text, and explore the dispersion of particular words. What does this tell you about the words, or the text? 2. < The program in Listing 3.2 used a dictionary of word counts. Modify the code that creates these word counts so that it ignores non-content words. You can easily get a list of words to ignore with: >>> ignored_words = nltk.corpus.stopwords.words(’english’) 3. < Modify the generate_model() function in Listing 3.5 to use Python’s random. choose() method to randomly pick the next word from the available set of words. January 24, 2008 24 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) Listing 3.5 4. < 3.2 to ﬁnd out how many word types account for a third of all word tokens, for a variety of text sources. What do you conclude about this statistic? Read more about this on LanguageLog, at archives/003993.html. 5. Ñ Write a program to generate a table of token/type ratios, as we saw in Table 3.4. Include the full set of Brown Corpus genres (nltk.corpus.brown.categories ()). Which genre has the lowest diversity (greatest number of tokens per type)? Is this what you would have expected? 6. Ñ Modify the text generation program in Listing 3.5. Bird, Klein & Loper 25 January 24, 2008 3.5. Counting Words: Several Interesting Applications Listing 3.6(wo ...’] January 24, 2008 26 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) 7. Ñ Write a program to print the most frequent bigrams (pairs of adjacent words) of a text, omitting non-content words, in order of decreasing frequency. 8. Ñ Write a program to create a table of word frequencies by genre, like the one given above for modals. Choose your own words and try to ﬁnd words whose presence (or absence) is typical of a genre. Discuss your ﬁndings. 9. Ñ Zipf’s Law: Let f(w) be the frequency of a word w in free text. Suppose that all the words of a text are ranked according to their frequency, with the most frequent word ﬁrst. conﬁrm Zipf’s law? (Hint: it helps to use a logarithmic scale). What is going on at the extreme ends of the plotted line? b) Generate random text, e.g. using random.choice("abcdefg "), taking care to include the space character. You will need to import random ﬁrst. Use the string concatenation operator to accumulate characters into a (very) long string. Then tokenize this string, and generate the Zipf plot as before, and compare the two plots. What do you make of Zipf’s Law in the light of this? 10. Ñ Exploring text genres: Investigate the table of modal distributions and look for other patterns. Try to explain them in terms of your own impressionistic understanding of the different genres. Can you ﬁnd other closed classes of words that exhibit signiﬁcant differences across different genres? 11. 12. Authorship identiﬁcation: Reproduce some of the results of [Zhao & Zobel, 2007]. Gender-speciﬁc lexical choice: Reproduce some of the results of. clintoneast.com/articles/words.php 3.6 WordNet: An English Lexical Database WordNet is a semantically-oriented dictionary of English, similar to a traditional thesaurus but with a richer structure. WordNet groups words into synonym sets, or synsets, each with its own deﬁnition. 3.6.1 Senses and Synonyms Consider the following sentence: (1) Benz is credited with the invention of the motorcar. If we replace motorcar in (1) by automobile, the meaning of the sentence stays pretty much the same: Bird, Klein & Loper 27 January 24, 2008 3.6. WordNet: An English Lexical Database (2) Benz is credited with the invention of the automobile. Since everything else in the sentence has remained unchanged, we can conclude that the words motorcar and automobile have the same meaning, i.e. they are synonyms. only has one sense in WordNet, as we can discover using len(). We can then ﬁnd deﬁnes Synsets. Let’s look at a word which is polysemous;’ 3.6.2 The WordNet Hierarchy WordNet synsets correspond to abstract concepts, which may or may not have corresponding words in English. These concepts are linked together in a hierarchy. Some are very general, such as Entity, State, Event these are called unique beginners. Others, such as gas guzzler and hatchback, are much more speciﬁc. A small portion of a concept hierarchy is illustrated in Figure 3.4. The edges between nodes indicate the hypernym/hyponym relation; the dotted line at the top is intended to indicate that artifact is a non-immediate hypernym of motorcar. WordNet makes it easy to navigate between concepts. For example, given a concept like motorcar, we can look at the concepts that are more speciﬁc; the (immediate) hyponyms. Here is one way to carry out this navigation: January 24, 2008 28 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) Figure 3.4: Fragment of WordNet Concept Hierarchy >>>} We can also move up the hierarchy, by looking at broader concepts than motorcar, e.g. the immediate hyperny}, Bird, Klein & Loper 29 January 24, 2008 3.6. WordNet: An English Lexical Database [{noun: artifact, artefact}, [{noun: whole, unit}, [{noun: object, physical_object}, [{noun: physical_entity}, [{noun: entity}]]]]]]]], [{noun: container}, [{noun: instrumentality, instrumentation}, [{noun: artifact, artefact}, [{noun: whole, unit}, [{noun: object, physical_object}, [{noun: physical_entity}, [{noun: entity}]]]]]]]]]]] A related method closure() produces a ﬂat version of this structure, with repeats eliminated. Both of these functions take an optional depth argument that permits us to limit the number of steps to take. (This is important when using unbounded relations like SIMILAR.) Table 3.5 lists the most important lexical relations supported by WordNet; see dir(wordnet) for a full list. Hypernym Hyponym Meronym Holonym Synonym Antonym Entailment more general animal is a hypernym of dog more speciﬁc dog is a hyponym of animal part of door is a meronym of house has part house is a holonym of door similar meaning car is a synonym of automobile opposite meaning like is an antonym of dislike necessary action step is an entailment of walk Table 3.5: ﬁnd ’] 3.6.3 WordNet Similarity We would expect that the semantic similarity of two concepts would correlate with the length of the path between them in WordNet. The wordnet package includes a variety of measures that incorporate this basic insight. For example, path_similarity assigns a score in the range 0]) January 24, 2008 30 Bird, Klein & Loper 3. Words: The Building Blocks of Language Introduction to Natural Language Processing (DRAFT) & Hirst, 2006]. 3.6.4 Exercises 1. < Familiarize yourself with the WordNet interface, by reading the documentation available via help(wordnet). Try out the text-based browser, wordnet.browse(). 2. < Investigate the holonym / meronym relations for some nouns. Note that there are three kinds (member, part, substance), so access is more speciﬁc, e.g., wordnet. MEMBER_MERONYM, wordnet.SUBSTANCE_HOLONYM. 3. Ñ Deﬁne a function supergloss(s) that takes a synset s as its argument and returns a string consisting of the concatenation of the glosses of s, all hypernyms of s, and all hyponyms of s. 4. Ñ Write a program to score the similarity of two nouns as the depth of their ﬁrst common hypernym. 5. Use one of the predeﬁned similarity measures to score the similarity of each of the following pairs of words. Rank the pairs in order of decreasing similarity. How close is your ranking to the order given here? (Note that this order was established experimentally by [Miller & Charles, 1998].) :: car-automobile, gem-jewel, journey-voyage, boy-lad, coast-shore, asylum-madhouse, magicianwizard, midday-noon, furnace-stove, food-fruit, bird-cock, bird-crane, tool-implement, brothermonk, lad-brother, crane-implement, journey-car, monk-oracle, cemetery-woodland, food-rooster, coast-hill, forest-graveyard, shore-woodland, monk-slave, coast-forest, lad-wizard, chord-smile, glass-magician, rooster-voyage, noon-string. 3.7 Conclusion In this chapter we saw that we can do a variety of interesting language processing tasks that focus solely on words. Tokenization turns out to be far more difﬁcult. Bird, Klein & Loper 31 January 24, 2008 3.8. Summary 3.8 Summary we can read text from a ﬁle punctuation. or tokens such as words and tokenization based on whitespace is inadequate for many applications because it bundles punctuation together with words lemmatization is a process that maps the various forms of a word (such as appeared, appears) to the canonical or citation form of the word, also known as the lexeme or lemma (e.g. APPEAR). a frequency distribution is a collection of items along with their frequency counts (e.g. the words of a text and their frequency of appearance). WordNet is a semantically-oriented dictionary of English, consisting of synonym sets synsets and organized into a hierarchical network. or 3.9 Further Reading For more examples of processing words with NLTK, please see the guides at. org/doc/guides/tokenize.html,, and. A guide on accessing NLTK corpora is available at:. 32 Bird, Klein & Loper This action might not be possible to undo. Are you sure you want to continue? We've moved you to where you read on your other device. Get the full title to continue reading from where you left off, or restart the preview.	https://www.scribd.com/document/98669964/NLP-Python-Intro-1-3	CC-MAIN-2017-04	refinedweb	24,896	62.58
In Progress import csv dropship files to website scpirt requires adaptation Budget £20-100 GBP We have an open cart site with approx 200 products we have 2 files from a drop shipper puckator one with categories and one with products, we want to put these into our store and be able to choose which products and categories to insert. We bought a module for inputting products from a cvs file but is not compatible, apparently the "script" needs changing. We have just inserted the files into excel files that we have included along with the module we bought. If possible we want to deal with other droppshippers so need something that will work for others also if possible. We are complete noobs at this so hope have explained things write.	https://www.freelancer.com/projects/XML-Script-Install/import-csv-dropship-files-website/	CC-MAIN-2017-47	refinedweb	131	62.01
In js/src/Makefile.in the jit_test.py script is called with "--valgrind" which causes some tests to timeout because running an ASan binary under valgrind doesn't work. I'm writing a patch that only passes --valgrind in the Makefile when MOZ_ASAN is not set. Created attachment 619528 [details] [diff] [review] Patch Comment on attachment 619528 [details] [diff] [review] Patch Review of attachment 619528 [details] [diff] [review]: ----------------------------------------------------------------- ::: js/src/Makefile.in @@ +605,5 @@ > ifneq ($(OS_ARCH),WINNT) # FIXME: this should be made work on Windows too. > #check:: check-malloc-function-usage FIXME: disable on JM until closer to merge time. > endif > > +ifneq ($(MOZ_ASAN),1) ifndef MOZ_ASAN Created attachment 619535 [details] [diff] [review] Updated patch Updated patch, addresses review comment. Keeping r+ from previous patch version. Marking also as a build blocker because this causes "make check" to run for the maximum allowed time per test using valgrind, rendering the builds very slow. Comment on attachment 619535 [details] [diff] [review] Updated patch	https://bugzilla.mozilla.org/show_bug.cgi?id=749768	CC-MAIN-2017-34	refinedweb	161	56.66
Adding a map to a web page has never been easier. All that’s required is a basic HTML document, the TomTom Maps SDK for Web, and a few simple lines of JavaScript code. In this article, my colleague, dev advocate Jose Rojas, will show you how! Adding a Map to a Web App With TomTom’s Maps SDK for Web, adding a map to a web page has never been easier. All that’s required is a basic HTML document, the SDK itself, and a few simple lines of JavaScript code. In this article, we’ll quickly show you how to do the following: - Register for a developer account. - Obtain an API key so you can use the SDK. - Create a simple application that displays a map centered at a hardcoded latitude and longitude. - Make a small change to the application to find the latitude and longitude for a desired location. You’ll find the full source for both versions of the application at. Getting the API Key In order to use the SDK, you need to obtain a developer account and an API key. The API key is free and authenticates you with TomTom so you can use all of the great features available in the SDK. If you haven’t already registered for a TomTom account, visit. There you’ll find a very short form, similar to the one below, that requests only basic information. When you click the “Register” button, you’ll be asked to solve a “captcha” to prove you’re human. After this, you’ll receive an email that allows you to activate your account. When you click the “Activate Account” button in that email, you’ll be brought back to a page like this: Click on “My Dashboard” to see the dashboard for your account, where you’ll find your first API Key. This is the key you’ll include in your application so you can use the SDK. The Web Page We’ll start with a simple web page that displays a map of the Golden Gate Bridge in San Francisco. At first, to keep things easy, we’ll hardcode the latitude (37.80776) and longitude (-122.47483) for this location. Referencing the SDK To use the SDK, we must first include a reference to it. TomTom offers three distribution channels: - Content Distribution Network (CDN)— the SDK is hosted on TomTom’s CDN. - Node.js Package Manager (NPM)— the SDK is hosted locally following installation by the Node.js package manager. - ZIP Files— the SDK is first downloaded, and unzipped, then locally hosted copies of these files are referenced in the application. The most straightforward approach is to use TomTom’s CDN, which is as simple as adding a few lines of code to the HEAD element of our HTML. That’s what we’ll use in our application. To include the CSS styling and the JavaScript necessary to display maps, add the following lines: <link rel="stylesheet" type="text/css" href=""> <script src=""></script> The SDK also includes services like the fuzzy search service, which allows us to search for information about a location (such as “Golden Gate Bridge”). To include the JavaScript necessary for these services, add the following: <script src=""></script> Notice that the URLs in these lines reference a specific version of the SDK(v.5.41.0). To find the URLs for the latest version, as well as information for other distribution options, visit. Once you’ve added the JavaScript, a global object named “tt” (TomTom) becomes available. You then reference map functions and objects via the “tt.map” namespace, and service functions and objects via the “tt.service” namespace. Placing the Map If we want to display a map, we need to set aside some space on our web page where the map will go. The easiest way to do this is to add a DIV element into the BODY of the HTML: <div id="map-div"></div> Notice that we include an identity (map-div) for the division to make it easy to reference later. We also want to size the division so there’s room to display the map. In this case, we’ll make the map covers 100% of the web page. We can accomplish this by adding the following CSS styling to the HEAD element of the HTML: <style> body, html { margin: 0; padding: 0; } #map-div { width: 100vw; height: 100vh; } </style> The Code Now that we’ve included the SDK and set aside a place to display our map, there’s only one step left: We need to add a little bit of JavaScript code to actually use the SDK. Since this is a simple application, we’ll include the code in-line, inside a SCRIPT element, within the BODY element of our HTML. If the application were to become more complex, we’d want to move this code in its own separate JavaScript file. Identifying the Application We’ll start by setting the product information for our application. While this isn’t strictly required, it allows TomTom to gather usage statistics for the application. const API_KEY = 'YOUR_API_KEY'; const APPLICATION_NAME = 'My Application'; const APPLICATION_VERSION = '1.0'; tt.setProductInfo(APPLICATION_NAME, APPLICATION_VERSION); You should edit this information to reflect your own product’s information. Where “YOUR_API_KEY” appears, replace it with the API key you obtained earlier in this article. Displaying the Map Next, we’ll create the map, associate it with the DIV element that will contain it, and center/zoom the map to the location we want (the Golden Gate Bridge). For simplicity, we hardcode the latitude and longitude of the location in a constant: const GOLDEN_GATE_BRIDGE = {lng: -122.47483, lat: 37.80776}; var map = tt.map({ key: API_KEY, container: 'map-div', center: GOLDEN_GATE_BRIDGE, zoom: 12 }); Notice that we choose a zoom level of 12, to display both the bridge and some of the surrounding city of San Francisco. Valid zoom levels range from 0 through 22. Higher zoom levels provide maps with greater detail, but covering a smaller area. With this code in place, our application to display a map of the Golden Gate Bridge is complete. It’s that easy! Finding a Location to Display In the real world, it’s unlikely we’ll know the latitude and longitude of our desired location. A common way of finding this information is to use the fuzzy search service provided by the SDK. Thankfully, we don’t have to do much to use this service. Changing our previous example is as simple as this: var map = ... tt.services.fuzzySearch({ key: API_KEY, query: 'Golden Gate Bridge' }) .go() .then(function(response) { map = tt.map({ key: API_KEY, container: 'map-div', center: response.results[0].position, zoom: 12 }); }); Most of the services in the SDK, including fuzzy search, execute asynchronously. They generally return a JavaScript Promise. To wait for the search to complete, we use the JavaScript Promise’s “then” function. There, we pass an anonymous callback function that displays a map of a location from the search results. In this callback function, we use code similar to what was presented earlier to display the map. The search response may include multiple matching results. In our code, we reference the position (latitude/longitude) of the first (and best) matching result. This result is contained in array element zero. Conclusion With very little code, we quickly created an application that can be used to display a map of any desired location. With no additional code, the map is also responsive, allowing the user to easily zoom and pan the map. Using the same SDK, you can easily enhance the application to allow users to search for their own locations, display routes between locations, and add a host of other features. - For complete documentation of TomTom’s Maps SDK for Web, visit: - For a list of additional tutorials on how to use the SDK, visit: Looking for another resource to build your map? Then check out our video on how to add your map to your website: I'm Ruanna, a content writer for TomTom Developers. This article originally appeared on developer.tomtom.com. The original author is Jose Rojas.	https://dev.to/tomtomdevs/how-to-add-a-map-to-your-website-in-30-seconds-edj	CC-MAIN-2020-40	refinedweb	1,362	63.19
How to set the working or current directory in the notebook? If I start sage in my directory ~/Sage/ then !pwd returns that directory. If I start a notebook though, the directory, given with import os os.getcwd() is a temporary directory within the /tmp tree. And if I try to change that directory with os.chdir("/home/me/Sage") then that change doesn't seem to "stick", in that the second time I call os.getcwd() it gives me the /tmpdirectory again. What I want to do is to run the Sage notebook in such a way that I can load files from its current working directory. I tried starting the notebook with notebook("/home/me/Sage") but it seems to make no difference. Unless of course the results of os are wrong. How can I fix the working directory for use within the notebook?	https://ask.sagemath.org/question/34537/how-to-set-the-working-or-current-directory-in-the-notebook/	CC-MAIN-2017-04	refinedweb	146	76.93
In this tutorial, we’ll see how you can use dotMemory to locate and fix memory leaks in your apps. But before moving on, let’s agree on what a memory leak is. What Is a Memory Leak? According to Wikipedia, impossible. Contents Sample App Step 1. Run Profiler Step 2. Get Snapshots Step 3. Compare Snapshots Step 4. Analyze Snapshot Step 5. Check for Other Leaks Sample App Once again, the app we’ll use for our tutorial is Conway’s Game of Life. Please download and unpack the archive before proceeding any further. Let’s assume we want to return some money spent on the Game of Life development and decide to add a couple of windows* that show various ads to users. Following worst practices, we show our ad windows windows use a timer (based on the DispatcherTimer class). You can see the implementation of the AdWindow class in the AdWindow.cs file. So, the feature is added and now is the best time to test it. Let’s run dotMemory and ensure that the ad window doesn't affect the app’s memory usage (in other words, it is correctly allocated and collected). Step 1. Run Profiler - Open the Game of Life solution in Visual Studio. - Run dotMemory using the menu ReSharper \| Profile \| Profile Startup Project (Memory). This will open the Profiler Configuration window. - In the Profiler Configuration window, turn on Start collecting allocation data immediately. windows will appear. - Click the Get Snapshot button in dotMemory. This will capture the data and add the snapshot to the snapshot area. Getting a snapshot doesn’t interrupt the profiling process, thus allowing us to get another snapshot. - Close the ad windows in our app. - Get a snapshot one more time by clicking the Get Snapshot button in dotMemory. - End the profiling session by closing the Game of Life app. The main page now contains two snapshots. Step 3. Compare Snapshots Now, we’ll compare and contrast the two collected snapshots. What do we want to see? If everything works fine, the ad windows Group by Namespace in the list of views. - Open the GameOfLifenamespace. What’s that? Two GameOfLife.AdWindowobjects are in the Survived objects column, which means that the ad windows are still alive. After we closed the windows, the objects should have been removed from the heap. Nevertheless, something prevented them from being collected. It’s time to start our investigation and find out why our windows were not removed! Step 4. Analyze Snapshot As mentioned in Tutorial 1 - Getting Started with dotMemory,object set consisting of two objects. To do this, click the number 2 in the Survived objects column next to the GameOfLife.AdWindowclass. As the object exists in both snapshots, dotMemory will prompt you to specify in which snapshot the object should be shown. Of course, we’re interested in the last snapshot where the windows should have been collected. - Select Open “Survived Objects” in the newer snapshot and click OK. This will show the object set “All objects of the AdWindow class that exist both in snapshot #1 and #2” in the Type List view. According to the view, the object set contains 2 instances with the shallow size of 952 B. These instances exclusively retain other objects with the total size of 10,676 B. We’re interested not in the AdWindowobjects themselves, but in those that retain our ad windows in memory. To figure this out, we should look at the selected object set using the Group by Dominators view. This will show us dominators---the objects that exclusively retain our ad windows in memory. - To view the list of dominators for the object set, click Group by Dominators in the list of views. As you can see, ad windows are retained in memory by event handlers, which, in turn, are referenced by instances of the DispatcherTimerclass. Let’s continue our investigation and try to find more details about those timer objects. - Right click the DispatcherTimer object set in the list and select Open this object set. This will open the DispatcherTimerobject set in the Type List view. Now, our goal is to understand how these timers relate to the AdWindowobjects. In other words, how the timers reference our ad windows. To get this info, we should dive deeper and take a look at the specific instance of the DispatcherTimerclass. - Open the Instances view and double click any instance of the DispatcherTimerclass. It doesn't really matter which one you choose, as they obviously have the same relationship with our ad windows. By default, the instance is shown using the Outgoing References view. This view is used to get the details on the instance’s fields and references. As you remember, the ad windows are retained by event handlers, which, in turn, are referenced by the DispatcherTimerinstances. The Outgoing References view shows how exactly this is happening---the ad window is referenced through the Tickevent handler. It appears that the AdWindowinstances are subscribed to the Tickevent of the timers. Let’s look at this in the code. - To quickly find the required call in the code, let’s use dotMemory. Simply switch to the Creation Stack Traces view. Here it is! The latest call in the stack that actually creates the timer is the AdWindow constructor. Let’s find it in the code. - Switch to Visual Studio with the GameOfLife solution and locate the AdWindow constructor: - Now, to make sure the leak is fixed, let’s build our solution and run the profiling again. Click the Profile item in dotMemory’s menu and repeat Step 2. Get Snapshots and Step 3. Compare Snapshots. That’s it! The AdWindowinstances are now in the Dead objects column which means they were area on the Snapshot Overview page, you’ll notice that dotMemory has an Event handlers leak check that already contains our AdWindow objects. Step 5. Check for Other Leaks We've fixed the event handler leak, and the ad windows are now successfully collected by GC. But what about the timers that caused our problems? If everything works fine, the timers should be collected as well and should be absent in the second snapshot. Let’s take a look. - Open the second snapshot in dotMemory. To do this, click the GameOfLife.exe step (the beginning of your investigation) 8 DispatcherTimerobjects in the heap. - Open the DispatcherTimerobject set by double clicking it. This will open the set in the Type List view. Now, we need to ensure that this set doesn’t contain the timers created by the ad windows. As the timers were created in the AdWindow constructor, the easiest way to do this is to look at the set using the Group by Creation Stack Trace view. - timers created by this call were not collected. They exist in the snapshot regardless of the fact that the ad windows were closed and removed from memory. This looks like one more memory leak that we should analyze. - Double click the AdWindow.ctor(Window owner) call. dotMemory will show us the object set (consisting of two timers) in the Type List view. To figure out what retains the timers in memory, let’s look at the Group by Dominators view. - Click Group by Dominators in the list of views. The list of dominators contains just one row, Not exclusively retained objects, which means that each timer is retained in memory by more than one object. In such cases, the best solution is to look at main retention paths of such 'not exclusively retained' object. For this purpose, dotMemory has a view called Group by Similar Retention. - Click Group by Similar Retention in the list of views. The Group by Similar Retention view groups objects in a set by similarity of their retention paths. In addition, this view shows the two most dissimilar retention paths for each group. Typically, this is enough to understand what prevents your object from being collected. - Click any timer in the list. As you can see, our timers have slightly different retention paths. In fact, they differ only in one additional PriorityItemobject; therefore, in our example there's no big difference which of the timer instances to analyze. The first retention path of our timers leads us to the DispatcherTimerlist, which is global and stores all timers in the app.: - Rebuild the solution. - Click the Profile item in the dotMemory’s menu and repeat Step 2. Get Snapshots and Step 3. Compare Snapshots. - Open the second snapshot in the Type List view. As you can see, there are only 6 DispatcherTimerobjects instead of 8 in the snapshot where we determined the leak. To ensure that GC collected the timers used by the ad windows, let’s look at these timers from the Group by Creation Stack Trace view. - Double click the DispatcherTimer objects and then click the Back Traces link in the list of views. Great! There is no AdWindow constructor in the list, which means that the leak has been successfully fixed. Of course, this type of leak doesn’t seem critical, especially for our app. If we didn’t use dotMemory, we may have never even noticed the issue. Nevertheless, in other apps (for example, server-side ones working 24/7) this leak could manifest itself after some time by causing an OutOfMemory exception.	http://confluence.jetbrains.com/display/NETCOM/Tutorial+2+-+How+to+Find+a+Memory+Leak+with+dotMemory	CC-MAIN-2016-07	refinedweb	1,557	66.33
I don't know what causes this. I have a function that looks something like this: def browse(self, args): win = GtkFileSelection("Select File to Export") win.connect("delete_event", win.hide) def file_selection_ok(_button, fs=win): self.file.set_text(fs.get_filename()) win.ok_button.connect("clicked", file_selection_ok) win.cancel_button.connect("clicked", win.hide) win.show() The * is a breakpoint. As you can tell,this shows a file selection box. The breakpoint should invoke when the user selects a file. It does, but when it happens, WingIDE and my whole X server freeze. I have to ctrl+alt+backspace out of it. As you can tell, that line would generate an error because self is out of scope. On the command line it gracefully tracebacks. In Wing, with or without the breakpoint, it crashes the X server. There's probably a conflict or something. BTW, if you can offer a suggestion on how to get self in scope I would love that. I'm not too experienced with GUI programming in Python. :) -- Ken Kinder	http://wingware.com/pipermail/wingide-users/2001-September/000834.html	CC-MAIN-2015-22	refinedweb	172	69.99
I was doing some research on common challenges developers face while building their Ionic apps, and one of the things that kept coming up was Deeplinking. For those not familiar, Deeplinking makes it possible to direct a user to content hidden deep in a native app, whether that’s from another app or a web browser. As web developers we live and breathe deep-linking because that was the major innovation of the web. Native apps are only just catching up, and so it hasn’t always been obvious how to link into an app the way we link into a webpage. Deeplinking as a concept has evolved heavily over the last few years, with mobile devices going from supporting custom URL schemes (like instagram://) to now opening native apps in response to navigation to URLs (like amazon.com). Additionally, OS’s now support powerful ways to index and search data inside of native apps. Each evolution in the deeplinking feature set has caused churn in both what mobile devices support and what they no longer support, making it a tall order to keep up. To help Ionic developers deeplink more easily, we are excited to announce a new, official way to deeplink into both Ionic 1 and Ionic 2 apps (and non-ionic Cordova apps): the Ionic Deeplinks Plugin along with Ionic Native 1.3.0. Let’s take a look at how it works: Choosing a Deeplink The first thing we need to do is figure out what kind of deeplink we want our app to respond to. Let’s say we run a Hat Shop and we have a website version of our store where we display our many fancy Hats. A URL to one of those Hats might look like. We can actually launch our app when someone navigates to this URL on Android or iOS and display the app version of the Hat product page. Additionally, let’s say we want to enable a custom URL scheme of the form ionichats://app/hats/very-nice-hat. Now that we have our URL scheme, website, and deeplinking path decided, let’s install the Deeplinks Plugin: Installing Ionic Deeplinks The Ionic Deeplinks plugin requires some variables in order to get set up properly: cordova plugin add ionic-plugin-deeplinks --variable URL_SCHEME=ionichats --variable DEEPLINK_SCHEME=https --variable DEEPLINK_HOST=ionic-hats.com In the install command, we provide the custom URL scheme we want to handle ( ionichats), the host domain we will respond to ( ionic-hats.com) and the host protocol we will listen for, which 99% of the time will be https as it’s required on iOS and Android. We’re almost ready to handle deeplinks, we just need to configure Universal Links on iOS and App Links on Android 6.0 so our app can open when navigating to ionic-hats.com. Configuring Universal Links (iOS) and App Links (Android) To configure iOS and Android, we need to enable Universal Links for iOS, and App Links for Android (6.0+). This process is primarily done on the server side of your website. You’ll publish a specific json file for iOS and one for Android, ensure your site is using HTTPS, and then configure your app to open in response to links to that domain. For Android, it pretty much Just Works from the plugin install above. However, for iOS, you’ll then enable the domain in the Associated Domains section of your entitlements, with the form applinks:yourdomain.com: You may also need to enable the entitlement from the Developer center for your app. Testing Deeplinks Assuming we have everything set up correctly (or at least we think we do), it’s time to start testing Deeplinks. On Android, this process is a snap. We can boot up our emulator or device, and send a deeplink intent directly to the app from the command line: adb shell am start -a android.intent.action.VIEW -d "ionichats://app/hats/very-nice-hat" io.ionic.hats Replacing the custom URL scheme and package name with your respective values. If everything was configured properly, our app will open, regardless of whether it was running or not! On iOS, I find it’s easier to test on the simulator. Start your app from X Code, go into the Contacts app and add a URL for one of the fake contacts so it looks like this: Tap on the link and our app should open! To test Universal Links on iOS, we can’t use the simulator (as far as I know, I couldn’t get it to work). Instead, we run our app on our iOS device, open safari and navigate to our URL. In Safari, when open on a page that has Universal Links enabled, we can swipe down to expose this bar: Universal Links on iOS are finicky. If you adjust the manifest, you’ll need to uninstall and reinstall the app in order for iOS to fetch it again, otherwise it’ll cache for 24 hours. If you are sure you’ve got everything configured properly but it’s still not working, double check your bundle identifer matches up with the manifest, you have the proper entitlements, you’re using HTTPS, you are sending application/pkcs7-mime as the content type for the manifest file, and try removing/installing the app again. (Here’s an example express.js route for serving the manifest for iOS) Responding to Deeplinks Getting the app configured is by far hardest part, and Universal Links is particularly finicky. Now that we (hopefully) have everything configured, it’s time to actually respond to our deeplinks! I’m going to assume you’re using Ionic 2 with Ionic Native which comes with convenient wrappers around many Cordova plugins to add Observable, Promise, and TypeScript support. Ionic Native works in any Cordova project regardless of whether it’s using Ionic 1/2, Angular 1/2, or TypeScript. See the Deeplinks README for examples for Ionic 1 and non-Ionic projects. To start, we define a set of deeplink routes we want to listen for. If one matches against an incoming deeplink, we can automatically navigate in our app to display the appropriate content. In Ionic 2, we can conveniently navigate with a specific instance of a Nav Controller, though we can also use the plain route method to handle the navigation ourselves (for example, if we want to do a very custom deeplink navigation). import {Component, ViewChild} from [email protected]/core'; import {Platform, Nav, ionicBootstrap} from 'ionic-angular'; import {Deeplinks} from 'ionic-native'; import {AboutPage} from './pages/about/about'; import {HatDetailPage} from './pages/hat/hat'; @Component({ template: '<ion-nav [root]="rootPage"></ion-nav>', }) class MyApp { @ViewChild(Nav) nav:Nav; constructor(private _platform: Platform) {} ngAfterViewInit() { this._platform.ready().then(() => { Deeplinks.routeWithNavController(this.nav, { '/about-us': AboutPage, '/hats/:hatId': HatDetailPage }); }); } }); ionicBootstrap(MyApp); Inside of our HatDetailPage, we can grab the hatId from the route: export class HatDetailPage { hatId: string; constructor(public nav: NavController, private _params: NavParams) { this.hatId = _params.get('hatId'); } } Take a look at a simple demo for Ionic 2 and one for Ionic 1 to see how the two differ. Conclusion That’s pretty much it! A lot of the work happens behind the scenes to make sure our app opens from both custom URL schemes and Universal Links, and that it functions from a cold boot (a deeplink received while the app is not running) as well as while running. Many people often confuse deeplinking with routing. The two are similar but subtly different. Routing helps an app navigate within itself while it’s running, as well as possibly from external links (especially in a traditional web app). Deeplinking, by contrast, is not used within the app for its own navigation, it’s only used to display a specific piece of content triggered from an external request. In that sense, you would not use the Deeplinks class for your own routing, only to enable the app to be launched from elsewhere on a user’s device. If you give the new plugin a try, let us know what you think. We are looking for feedback on how to make this easier, and plan to make Deeplinking a major feature in Ionic apps going forward.	https://blog.ionic.io/deeplinking-in-ionic-apps/	CC-MAIN-2017-26	refinedweb	1,381	58.21
- How to use "File" library in Console C++? - "Press any key to continue" Error on console - Question about getting an info class from another Form - New to this forum and C# - Need some help - namespace location? - Getting an embedded resource - Comparing values of generic types - Programmatically creating nodes in a treeview problem - Using 'new' to replace GetType() when using generics - Draw dot by dot? - Which DLL - lock - how to change a random variable to double ? - Generic and Iterator - Generic Operator Overloading - Events - textButton array using Microsoft Visual Designer - ConfigurationSettings.GetConfig() always returns null - Overrriding - Equals() - Running Command Prompt Functions - system("pause") in C#? (warning: noob question) - My options for Directx - Make a mirror program. - Back buffering with GDI and System.Drawing.Graphics - A question... - Master Mind - Random -	http://cboard.cprogramming.com/sitemap/f-13-p-31.html?s=0fc33af3ba553727c4caa2e032a78d91	CC-MAIN-2015-22	refinedweb	127	50.53
Calculate process time in Java Calculate process time in Java ... the process time of the completion of the operation through the Java program... for the best illustration of the procedure of calculating the process time in which any Java Util Examples List program. Calculate process time in Java This section provides the facility to calculate the process time of the completion... examples that demonstrate the syntax and example code of java util package Java example to calculate the execution time Java example to calculate the execution time get execution time This example program... of the program or method by the ending time of the method. In our example java calculate the time .. calculate the time .. [CODE] Elapsed Time Example...() { startTime = new Date(); alert("Time Started...(); alert("Time Stopped"); } function calculateTimeElapsed Lang and Util Base Libraries Lang and Util Base Libraries The Base libraries provides us the fundamental features and functionality of the Java platform. Lang and Util Packages Lang and Util package provides the fundamental classes and Object of primitive type to calculate the difference between two dates in java - Java Beginners to calculate the difference between two dates in java to write a function which calculates the difference between 2 different dates 1.The function should accept 2 different dates (in the format dd/mm/yyyy hh:mm:ss AM/PM) 2.The java util date - Time Zone throwing illegal argument exception java util date - Time Zone throwing illegal argument exception ...()); The date object is not getting created for IST time zone. Java... an exception ? This piece of code is running on app servers on machines in different time util util Write a programe such as whenever any user enter the name of a country it displays the current date and time and ist also calculate difference between two time in jsp calculate difference between two time in jsp How to calculate difference between two dates count occourance no of time no between 0 to 9 given by user in java count occourance no of time no between 0 to 9 given by user in java ...++; } else if(no==2...); }catch(Exception e){} } } Here is a java time time how to find the current system time between the user login and logout using java Calculate sum and Average in java Calculate sum and Average in java How to calculate sum and average in java program? Example:- import java.io.BufferedReader; import.... Description:- In this example we are calculating sum and average of n numbers java - Development process java What is the difference between j2sdk1.4 version and j2sdk1.5... Collection framework better. Many additions for jdk1.5 than jdk1.4 For example : 1. import static 2. generic type 3. assertion 4. enum The base of JDK1.4 Java Time Zone Example Java Time Zone Example Converting time between time zones In this section we have written a java program which will take two Time Zone IDs as its argument and then convert util date Java util date ... date and time. It's no arguments constructor creates date object specifying current date and time. It can be created specifying year, month, date. Years Examples Chapter 2. Design, build and test web components chain.doFilter(req, resp); // Calculate the difference between the start... Chapter 2. Design, build and test web... between client and server. Filters are Web components that typically Struts 2 Tutorial on Struts 2 framework. Writing Jsp, Java... function in Struts 2. We have provided fully tested example code to illustrate the concepts. Struts 2 datepicker Example Java get Elapsed Time Java get Elapsed Time .... As you all know that the Elapsed time is the time taken to complete the process... time and the end time of the defined process. Here we are calculating the sum Thread and Process - Java Beginners Thread and Process Dear Deepak Sir, What is the diffrence between Thread and Process.Give an example with explanation. Thnaks & Regards, VijayaBabu.M Hi vijayaBabu A process can contain multiple threads Struts 2 datetimepicker Example Struts 2 datetimepicker Example ... to create date time picker. The <s:datetimepicker .../> tag The Struts 2 <s...;Struts 2 Format Date Example!</title> <link href="<s Java Program - Development process Java Program Assume that the bank maintains two kinds of accounts.... - Customer type which is of character type and can have only 2 values C or S. C... calculateBalance( ) ; This method is overridden in the two subclasses. 2. Curr-accnt class mapping between java class and more than 2 tables mapping between java class and more than 2 tables Association mapping of table in hibernate Hi Friend, Please visit the following link: Hibernate Tutorial Thanks Java - Development process the sum of geometric series?a+ar+ar^2+ar^3+??+ar^n-1 Q 6- write a program in java... in java to sum series?x+x^2+x^3+x^4+ ??..+x^n Q12 write a program in java...+2+4+7+14 ) Q13 - write a program in java using loops and switch statements Java Interview Questions - Page 2 Java Interview Questions - Page 2 .... Question: What is the main difference between Java platform and other... Virtual Machine (Java VM) 2. The Java Application Programming Interface Decreasing process time by caching through the Hash Table in Java Decreasing process time by caching through the Hash Table in Java... illustrates you how to improve the process time of any type of the operation performed by your java program. You can easily improve the process completion time Write a program to calculate area and perimeter of a circle example will teach you the method for preparing a program to calculate the area... Write a program to calculate area and perimeter of a circle...; under Java I/O package and define and integer r=o, which is the radius Time validation Time validation Hi. I have a text box in html to get time... box is in the correct format or not using java script. Please help me for doing project. Here is a code that accepts the time in the format hh:mm core java - Development process core java Hi i want core java code for this problem.its urgent... is divided up into a grid to simplify navigation. An example position might.... INPUT AND OUTPUT Test Input: 5 5 1 2 N LMLMLMLMM 3 3 E MMRMMRMRRM Week calculate start from friday Week calculate start from friday My problem is to calculate how many... number of weeks for the selected month. example: if i select year in 2010 Java Programming: Chapter 2 Quiz Quiz Questions For Chapter 2 THIS PAGE CONTAINS A SAMPLE quiz on material from Chapter 2 of this on-line Java textbook. You should be able... an example to illustrate the difference between a syntax error and a semantics error How to calculate area of rectangle How to Calculate Area of Rectangle In this section we will learn how to calculate area... with the complete java source code. Description of this program In this program Struts 2 Login Form Example Struts 2 Login Form Example tutorial - Learn how to develop Login form in Struts 2 though this video tutorial In this video tutorial I will explain you how.... Let's start developing the Struts 2 Login Form Example Step 1 Adding time span example Adding time span example In this example java program we have added the two time spans... with the date 10 October 2008. Now suppose we want to add 2 Months in this time span Calculate Company's Sale using Java Calculate Company's Sales Using Java In this section, you will learn how to calculate Company's sale. A company sales 3 items at different rates and details..."); System.out.println("2. Tuesday"); System.out.println("3. Wednesday Java Programming: Chapter 2 Exercises Programming Exercises For Chapter 2 THIS PAGE CONTAINS programming exercises based on material from Chapter 2 of this on-line Java textbook... be made up of a bunch of 's. For example, if your initials were "DJE Find in Array - Calculate Occurrences of Elements in Array Find in Array - Calculate Occurrences of Elements in Array... to calculate occurrences of elements in an array. Occurrences means, the how many...;javac OccurancesInArray.java C:\chandan>java OccurancesInArray How many task 2 - Java Beginners task 2 Write a time server that follows the time protocol outlined in RFC 868. When a client connects, the server sends a 4-byte, big-endian, unsigned integer specifying the number of seconds that have passed since 12:00 A.M. Java Get Example to calculate the execution time This example program will describe you the way that how one can calculate or get the execution time of a method or program in java... by the ending time of the method. Java example to get call by reference - Development process call by reference Hello , Is thre callbyvalue in java or not? can any one also say the difference between callbyvalue and callbyreference... to. In Java, you cannot pass objects as parameters, only references to objects calculate size of array calculate size of array Is it possible to calculate the size of array using pointers in Java Core Java Interview Questions Page 2, Core Java QuestionQ Core Java Interview Questions -2 ...: The process of converting one datatype to another in Java language is called Casting... classes and it is highest-level class in the Java class hierarchy. Instances Javascript calculate number of days between two dates Javascript calculate number of days between two dates In this tutorial, you will learn how to calculate number of days between two dates.For this, you need... by the corresponding number of milliseconds. Example: <html> <head> <script Custom Annotation - Development process , Custom Annotation 1)Annotations are metadata of a data. 2)Annotations to annotate a Java element. 3)An annotation show the declared element... compile time. 7)It can be used before compile time mainly to generate Flex 3 data binding process and example object to another object and is a process to pass data between different layer... control with this value. Output:- Running example: 2. Data... and destination properties for bind data between objects. In this example user Java Subtracting Time Span Java Subtracting Time Span In this example java program we have subtracted the two... suppose we want to subtract 2 Months in this time span with the use of add() method Difference between error and exception ???????? Difference between error and exception ? Can we handle a error in java if yes than give an code of an example? Difference between error... yourself or that might be thrown because of an obvious run-time error such as trying Calculate the Sum of three Numbers Calculate the Sum of Three Numbers This is simple java programming tutorial . In this section you will learn how to calculate the sum of three numbers by using three java time - Java Beginners java time Hi, Iam created a desktop login application using...()); pstmt.setDate(2, sqlDate); java.sql.Time sqlTime = new java.sql.Time(new...(2, sqlDate);/ pstmt.executeUpdate(); pstmt.close(); conn.close Date & TIme - Development process Date & TIme Hi, I asked to insert Date and Time to database with am... with time. Hi Friend, To insert the date,use the following code in your...() that will insert date with time into database. So to use this method, you have core java - Development process . The process is known instantiation For example : class... to : Time Picker in struts 2 - Struts ;head> <title>Struts 2 Time Picker Example!</title>...Time Picker in struts 2 How to create Time Picker in Struts 2 ? ...;</ul>2. struts.xml (Add the following code)<action name=" Java Project - Development process Java Project Hello Sir I want Java Project for Time Table of Buses.that helps to search specific Bus Time and also add ,Update,Delete the Bus Routes. Back End MS Access Plz Give Me Java process Java process How will you invoke any external process in Java java code - Development process java code to setup echo server and echo client. Hi Friend, Please visit the following links: Hope - Development process java Could you please explain me how to use composite primary key in the java persistent api with example How to calculate area of triangle .style1 { margin-right: 0px; } How to Calculate...; In this section we will learn how to calculate area of triangle. We... of triangle. Description of this program This is very java programming Difference between Encapsulation and Abstraction in Java In this section we will discuss about the difference between Encapsulation and Abstraction in Java. Encapsulation is a process of hiding all the data.... Encapsulation in Java is represented using private, package-private Calculate sum of even and odd numbers in Java Calculate sum of even and odd numbers In this section, you will learn how to read the file that contains even and odd numbers and calculate their sum... numbers from the file and then calculate their sum. Here is the code Struts 2 Guide example of Struts 2 in this Complete application development tutorial series...;Hello World" example. So, work hard to learn the process of development and deployment of "Hello World" quick Struts 2 guided tutorial. Example java - Development process Using Array in Java What is Array ..and when should i use it in my application? Java Array Program CodeDeclaration of an array :int arr...++ ){ System.out.print(" " + arr[i]); } } }Java Array time decrement time decrement i want to know calculate the time for 2 minutes(from current time started),after that the button in the page will be disable Hi, Here is the complete code example. Button will be disabled after 1 Java - Development process to integrate two java program. u can integrate java pro with other software or tool. To integrate 2 java programs use "is a relationship" and "has a relationship" ie... to integrate the two or more class in java language.please send the message difference between servletconfig and servletcontext in java difference between servletconfig and servletcontext in java difference between servletconfig and servletcontext in java ServletContext... to communicate with its servlet container, for example, to get the MIME type of a file Comparison between the types of sorting in java Comparison between the types of sorting in java welcome all i wanna program in java compare between selection,insertion,bubble,merge,quick sort In terms of timer and put all types in frame and find the timer for example array What is difference between the java and javascript? What is difference between the java and javascript? What is the difference beteen the java and javascript? Hello Friend, Difference: 1) Java is a Object Oriented programming language developed by Sun Microsystems java collection - Development process . Comparing and Creating new list in Java Java Example code for creating... Example code for creating and comparing lists using Java. import java.util....java collection - creating and comparing lists using Java How Process in Java Process in Java how can I execute a java program as a process which i can monitor it in the task manager to see the cpu usage java programming - Development process a program in java to generate the following pattern 1=1 1+2=3... a program in java to sum series?x+x^2+x^3+x^4+ ??..+x^n Q12 write a program... itself i.e 28=1+2+4+7+14 ) Q13 - write a program in java using loops and switch code in java - Development process :// Hope java - Development process java hi, can u send an example code in MVC Architecture for gym process i just want to get register id from database for citizen .then he will add... some links where u can find appropriate example regarding your problem. http java programming - Development process java programming Implement Lisp-like list in Java. Write basic operations such as 'car', 'cdr', and 'cons'. If L is a list [3, 0, 2, 5], L.car...); l.add(2); l.add(5); Lisp L=new Lisp(); int val=L.car(l); System.out.println calculate difference between two dates calculate difference between two dates hi, I was actually working on to calculate the number of days between two dates of dd/mm/yyyy format... the difference between the two dates java - Development process java sir, i need Implement Lisp-like list in Java. Write basic operations such as 'car', 'cdr', and 'cons'. If L is a list [3, 0, 2, 5], L.car...); l.add(0); l.add(2); l.add(5); Lisp L=new Lisp(); int val=L.car(l java algm - Development process java algm tell me below program algorithm sir. PROGRAM: import java.util.*; class Lisp { public int car(List l){ Object ob=l.get(0... ArrayList(); l.add(3); l.add(0); l.add(2); l.add(5); Lisp L=new Lisp(); int Programming: Chapter 2 Quiz Answers Sample Quiz Answers For Chapter 2 THIS PAGE CONTAINS SAMPLE ANSWERS to the Quiz on Chapter 2 of this on-line Java textbook. Note... of a programming language. Give an example to illustrate the difference between a syntax Core-Java - Development process =str+"Dixit"; if my application excute above line 100 times then some time it append second part some time it is not appending. how i can solve this problem.i m.../java Introduction to Struts 2 Framework , Java Beans, ResourceBundles, XML etc. Struts 2 Framework is very... size. Comparison between Struts 1 and Struts 2 frameworks...Introduction to Struts 2 Framework - Video tutorial of Struts 2 In this video Java - Development process = in.readLine(); str += ", This is the example of SringBuffer class...()); } } } ------------------------------------------------- Read for more information, java - Development process java Design a Vehicle class hierarchy in Java. Write a test program to demonstrate polymorphism.and output.please reply must sir. Hi...){ Vehicle[] v = new Vehicle[3]; v[0]= new Bus(); v[1]=new Car(); v[2 core java - Development process core java Hi i want core java code for this problem.its urgent... bar at 0.85 Input 2: 1 imported box of chocolates at 10.00 1 imported bottle... bar: 0.85 Sales Taxes: 1.50 Total: 29.83 Output 2: 1 imported box java - Development process _no= 'R2' and tow_no = 2 " it should show flat availabilty .the above query... where sec_no= 'R2' and tow_no = 2 " Do some changes for working of query..._no = 2 " For any more problem give details and full code to solve Difference between Struts and Spring To know the difference between Struts and Spring, we must first explain and understand both the frameworks a little. Spring framework is a Java platform that is used to develop modular, portable and testable Java applications java program - Development process java program hi, i need a simple program for converting given infix...(ch, 2); break; case '(': stack.push(ch...; else prec2 = 2; if (prec2 < prec1 JAVA - Development process Internationalization in JAVA Please explain the concept of Internationalization and internationalization in java with example? ... internationalization.Here is the example of Internationalization in JAVA Core JAVA - Development process ); } } ------------------------------------------------------ Read for more information with Example. Thanks & regards Amardeep java script - Development process java script Hi guys, can anybody tell me how to create menu box using DHTML i want source code please help me its very urgent ... Menu Item3 2)Menu.js: function createMenu	http://roseindia.net/tutorialhelp/comment/81995	CC-MAIN-2014-15	refinedweb	3,211	56.05
Welcome to WindowsClient.net \| \| Join > Learn > Windows Forms FAQs Here are some frequently asked questions about Windows Forms and their answers. For a single row select DataGrid, you can get both these behaviors by using a custom column style and overriding its Edit method. In your override, handle unselecting and selecting the current row, and DO NOT call the base class. Not calling the base class keeps the cell from becoming active. Here is a code snippet suggesting how this might be done. You can download a full working project (CS, VB). public class DataGridNoActiveCellColumn : DataGridTextBoxColumn { private int SelectedRow = -1; protected override void Edit(System.Windows.Forms.CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible) { //make sure previous selection is valid if(SelectedRow > -1 && SelectedRow < source.List.Count + 1) this.DataGridTableStyle.DataGrid.UnSelect(SelectedRow); SelectedRow = rowNum; this.DataGridTableStyle.DataGrid.Select(SelectedRow); } } If you want to handle multi-selections, then there is more work to be done. One solution is to still override Edit as above, but have an empty implementation. Do not have the code the handles the selected row and do not call the base class. To handle the selections in this case, subclass the DataGrid and override its OnMouseDown virtual method to change all cell clicks into row header clicks. Also override OnCurrentCellChanged to handle moving the current cell with the keyboard. You can download a sample (C#, VB) that implements this functionality. Contributed from George Shepherd's Windows Forms FAQ Contact \| Advertise \| Issue Management by Axosoft's OnTime \| Running IIS7All Rights Reserved. \| Terms of Use \| Trademarks \| Privacy Statement© 2012 Microsoft Corporation.	http://windowsclient.net/blogs/faqs/archive/2006/05/30/how-do-i-make-a-datagrid-never-have-an-active-edit-cell-and-always-select-whole-rows-as-in-a-browser-style-grid.aspx	crawl-003	refinedweb	270	50.33
Hello, fellow Developers! Have you heard about that challenge called Advent of Code:? “Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.” as its author Eric Wastl explains. While it is nothing SAP-specific, my teammates from SAP Developer Advocates team DJ Adams, Marius Obert, Maximilian Streifeneder, Rich Heilman and people from our SAP community (Nabheet Madan, Christian Drumm, Gregor Brett, Leo van Hengel, Hendrik Neumann to mention those I am aware of) joined it. Because the requirements are simple: you love to code, you love to have fun, you love to learn. Do you feel like all these are close to your heart? Then join and let us know in comment! Already participating, but not listed above? Please let us know in the comments as well! You can use whatever programming language or tool you know or you want to learn. Maxi is using Java, Nabheet is using ABAP, Gregor is using Elixir, Rich used HANA SQLScript, while I am using Python and … SAP Data Hub, dev edition. Why SAP Data Hub? Because … why not. Yes, it is overkill. But — as I mentioned — the idea is to learn and to have fun. If you watch that great talk of Eric from two weeks ago (and it is must-watch for many reasons), then you hear about people using Excel, Google Sheets, Minecraft and even paper to solve those puzzles. 🙂 So, here is my solution of the first puzzle from day 2 using Data Hub: …with the following code for the Python3 operator def on_input(data_in): data= data_in intcode_str = data.rstrip().split(',') intcode_str[1:3]=['12','2'] intcode_int = list(map (int, intcode_str)) result = intcode_int cursor = 0 while result[cursor] != 99: result[result[cursor+3]] = result[result[cursor+1]] + result[result[cursor+2]] if result[cursor]==1 else result[result[cursor+1]] * result[result[cursor+2]] cursor += 4 api.send("result", result[0]) api.set_port_callback("input", on_input) You can import the complete data pipeline code from my GitHub repo: Let’s start the pipeline. Open the Terminal’s UI once the pipeline is running. Provide the input from the puzzle, which for me was: 1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,13,1,19,1,5,19,23,2,10,23,27,1,27,5,31,2,9,31,35,1,35,5,39,2,6,39,43,1,43,5,47,2,47,10,51,2,51,6,55,1,5,55,59,2,10,59,63,1,63,6,67,2,67,6,71,1,71,5,75,1,13,75,79,1,6,79,83,2,83,13,87,1,87,6,91,1,10,91,95,1,95,9,99,2,99,13,103,1,103,6,107,2,107,6,111,1,111,2,115,1,115,13,0,99,2,0,14,0 …and get the result 4714701 received from the Python operator and displayed in the Terminal. Are you in? Should you be joining that challenge (not necessarily for the sake of leaderboard, but for the sake of knowledge, fun and support) or already joined — let us know in the comment. And do not forget to include links to your code, to your blog posts, or other online resources you created for this year’s Advent of Code, no matter languages or tools you are using! Happy coding ⌨️ -Vitaliy (aka @Sygyzmundovych) Nice one Witalij. I just wanted to highlight a couple of things for folks here: Happy hacking!	https://blogs.sap.com/2019/12/04/adventofcode-challenge-2019.-are-you-in/	CC-MAIN-2020-05	refinedweb	605	72.87
Mission8_Servo_Motor In this mission, you will use another kind of motor, the servo motor. The angle of its arm will change with the potentiometer. What you need The parts you will need are all included in the Maker kit. - SwiftIO board - Shield - Servo - Potentiometer module - 4-pin cable Circuit Place the shield on top of your SwiftIO board. Connect the potentiometer module to pin A0 using a 4-pin cable. Connect the servo to the pin PWM4A. The servo has three wires: the ground wire is brown, the power wire is red, and the signal wire is orange. Example code // Import the SwiftIO library to use everything in it. import SwiftIO // Import the board library to use the Id of the specific board. import MadBoard // Initialize the analog pin and PWM pin. let a0 = AnalogIn(Id.A0) let servo = PWMOut(Id.PWM4A) while true { // Read the analog value and return a value between 0.0 and 1.0. let value = a0.readPercent() // Calculate the value to get the pulse duration. let pulse = Int(500 + 2000 * value) // Set the servo position according to the pulse. servo.set(period: 20000, pulse: pulse) sleep(ms: 20) } Background Servo motor The servo motor can adjust its arm's position according to the signal. You can set PWM output to control it. This servo requires a pulse every 20ms. And the duration of each pulse determines the position of the arm: - If the high voltage lasts for 0.5ms, the arm will be at 0 degrees. - If the high voltage lasts for 1.5ms, the arm will be at 90 degrees. - If the high voltage lasts for 2.5ms, the arm will be at 180 degrees. note This servo needs the pulse to be in the range of 0.5 to 2.5ms. You may also meet other servos that need a pulse in 1 to 2ms. Code analysis import SwiftIO import MadBoard Import the two libraries: SwiftIO and SwiftIOBoard. SwiftIO is used to control the input and output of the SwiftIO board. SwiftIOBoard defines the pin name of the board. let a0 = AnalogIn(Id.A0) let servo = PWMOut(Id.PWM4A) Initialize the analog pin A0 for the potentiometer and the PWM pin PWM4A for the motor. let value = a0.readPercent() let pulse = Int(500 + 2000 * value) servo.set(period: 20000, pulse: pulse) sleep(ms: 20) In the dead loop, read the input value in percentage, so you get a value between 0 and 1. You will use this method set(period:pulse:) to set the PWM. The period is in microseconds, so it is 20000us. The pulse should be the number between 0.5ms to 2.5ms. So the value will be matched into this range by doing some calculations. Reference PWMOut - set the PWM signal. AnalogIn - read the voltage from an analog pin. SwiftIOBoard - find the corresponding pin id of SwiftIO board.	https://docs.madmachine.io/tutorials/swiftio-maker-kit/mission8	CC-MAIN-2022-21	refinedweb	479	78.55
One reason why it is difficult to develop software for mobile devices is that the hardware is not the best compared to deploying to a console or a “real” computer. Resources are limited. One particularly sparse resource is RAM. Out of memory exceptions are common on both Android and iOS if you’re dealing with large files. Recently, when building a Google VR 360 video player, we went over the 1GB of RAM available on older iOS devices pretty quickly. What Not to Do One of my big complaints about the Unity manual and many tutorials is they usually just show you how to do something really quickly and don’t always tell you the exact use case or how it can just flat out fail. For example, using the relatively new UnityWebRequest, you can download a file over HTTP like this: private IEnumerator loadAsset(string path) { using (UnityWebRequest webRequest = new UnityWebRequest(path)) { webRequest.downloadHandler = new DownloadHandlerBuffer(); webRequest.Send(); while (!webRequest.isDone) { yield return null; } if (string.IsNullOrEmpty(webRequest.error)) { FileComplete(this, new FileLoaderCompleteEventArgs( webRequest.downloadHandler.data)); } else { Debug.Log("error! message: " + webRequest.error); } } } These are all off the shelf parts from Unity, with the exception of the FileLoaderCompleteEventArg but just assume that we use that to pass off the downloaded bytes as an array eg: byte[]. Notice this returns an IEnumerator and utilizes yield statements so it should be run in a Coroutine. What happens here is that the UnityWebRequest will open up a connection to the given path, download everything into a byte array contained within the DownloadHandlerBuffer. The FileComplete event will fire if there are no errors, sending the entire byte array to the subscribing class. Easy, right? For small files, sure. But we were making a 360 Video player. Our max resolution was 1440p. The first sample files we got for testing were bigger than 400MB. The iPhone 7, with 2GB of RAM, took it like a champ. The iPhone 6, with 1GB of RAM, crashed like a piano dropped from a helicopter. Why Did my App Just Crash? Let’s look at the guts of these components. The main focus is on the DownloadHandlerBuffer object. When it is first created, it will start by preallocating memory for a small byte array where it will store all the downloaded bytes. As the bytes come in, it will periodically expand the size of the array. In our test case, it was expanding the array until it could hold 400MB. And because each additional allocation is a guess, it will most likely overshot that amount. Note, I am speculating here because I have not looked at the source code for the DownloadBufferHandler. There is a chance it allocates space based on the Content-Length header returned with the HTTP Response. But, the result is the same; it will use up at least 400MB of RAM. That’s 40% of the 1GB that the iPhone 6 has! We’re already in dangerous territory. I know what you’re saying, “Steff, why did it crash if we only used 40% of the RAM?” There are two ways to find the answer. One (and give Unity credit here) is in the documentation for DownloadHandlerBuffer. Note: When accessing DownloadHandler.data or DownloadHandler.text on this subclass, a new byte array or string will be allocated each time the property is accessed. So, by accessing the data property, Unity allocates an additional 400MB of memory to pass off the byte array into the EventArg. Now we have used 800MB of RAM just on handling this one file. The OS has other services running plus you very likely have RAM allocated for bitmaps and UI and logic. You’re doomed! Profiling Memory Allocations If you didn’t read the docs, and they’re long: I get it, you could have found this memory leak by running the application in Unity while using the Profiler AND by running the application on an iOS device while using a valuable free tool from Apple: Instruments. The Allocations instrument captures information about memory allocation for an application. I recommend using the Unity Profiler heavily for testing in the Editor and then continuing performance testing on device for each platform. They all act differently. Using the Profiler in the Editor is only your first line of defense. In this case I only properly understood what was happening when I watched it unfold in a recording using the Allocations instrument. Streams to the Rescue There is a way to download large files and save them without using unnecessary RAM. Streams! Since we plan on immediately saving these large video files in local storage on device to be ready for offline viewing, we need to send the downloaded bytes right into a File as they are received. When doing that, we can reuse the same byte array and never have to allocate more space. Unity outlines how to do that here, but below is an expanded example that includes a FileStream: public class ToFileDownloadHandler : DownloadHandlerScript { private int expected = -1; private int received = 0; private string filepath; private FileStream fileStream; private bool canceled = false; public ToFileDownloadHandler(byte[] buffer, string filepath) : base(buffer) { this.filepath = filepath; fileStream = new FileStream(filepath, FileMode.Create, FileAccess.Write); } protected override byte[] GetData() { return null; } protected override bool ReceiveData(byte[] data, int dataLength) { if (data == null \|\| data.Length < 1) { return false; } received += dataLength; if (!canceled) fileStream.Write(data, 0, dataLength); return true; } protected override float GetProgress() { if (expected < 0) return 0; return (float)received / expected; } protected override void CompleteContent() { fileStream.Close(); } protected override void ReceiveContentLength(int contentLength) { expected = contentLength; } public void Cancel() { canceled = true; fileStream.Close(); File.Delete(filepath); } } And to use the above in our coroutine: private IEnumerator loadAsset(string path, string savePath) { using (UnityWebRequest webRequest = new UnityWebRequest(path)) { webRequest.downloadHandler = new ToFileDownloadHandler(new byte[64 * 1024], savePath); webRequest.Send(); ... ... } } Looking first at our new ToFileDownloadHandler, we extended Unity’s DownloadHandlerScript and have overridden the required methods. The magic happens in two places. First, we pass in a byte array to the base class via the constructor. This let’s Unity know that we want to re-use that byte array on each ReceiveData callback where we only allocate a small amount of RAM once. Second, we use a FileStream object to write the bytes directly to our desired file. The rest of the code is there to handle canceling the request. Whenever you deal with FileStream objects, you must remember to close them out when you’re done. Looking at the loadAsset method, we added a parameter for the path to where the file will be saved locally and we defined the size of the buffer at 64MB. This size is dependent on your network speeds. We were focussed on WiFi connections, so a larger buffer made sense. Too small and you will make the download take longer than necessary to complete. Where to Go from Here Now you have an understanding of one way that your application can eat up RAM. If you only take away one thing from reading this post it’s this: for managing memory allocations, streams are your friends. And you should be constantly performance testing as you develop your application, unless you’re trying to maximize one-star reviews in the App Store. Gotchyas One final note on the code above: we did not end up going to production using UnityWebRequest on iOS. When we tried using a similar streaming solution as above, we found that the request was not clearing from memory if it was canceled due to the user sending the application to the background. Using the Time Profiler Instrument showed that NSURLSession objects were not being cleaned up when the application paused and resumed, so eventually the CPU would max out and crash. We had to seek an alternative solution for iOS using a native plugin. However, in the final code we still used HTTP streaming directly into a file via FileStream. Just not wrapped up in UnityWebRequest objects.	https://thoughtbot.com/blog/avoiding-out-of-memory-crashes-on-mobile	CC-MAIN-2020-45	refinedweb	1,332	55.03
I have a large numpy 1-d containing about 700,000 classes. In addition, I have another similar sized array which contains the new values of the classes. Example arrays original_classes = np.array([0,1,2,3,4,5,6,7,8,9,10,10]) new_classes = np.array([1,0,1,2,2,10,1,6,6,9,5,12]) >>> reclassify_function(original_classes, new_classes) array([ 1, 1, 1, 1, 1, 12, 1, 1, 9, 12, 12]) You could use scipy.sparse.csgraph.connected_components to relabel your classes. For your example data: from scipy.sparse import csr_matrix from scipy.sparse.csgraph import connected_components A = np.array([0,1,2,3,4,5, 6,7,8,9,10,10]) B = np.array([1,0,1,2,2,10,1,6,6,9,5 ,12]) N = max(A.max(), B.max()) + 1 weights = np.ones(len(A), int) graph = csr_matrix((weights, (A, B)), shape=(N, N)) n_remaining, mapping = connected_components(graph, directed=False) print mapping[A] Gives: [0 0 0 0 0 1 0 0 0 2 1 1] These are the relabeled classes. I'm sure you can figure out how to express these in terms of the input data. Note for best performance the "original" and "new" classes should be a single range of consecutive integers without gaps.	https://codedump.io/share/aXiqGW67Bs8s/1/vectorized-numpy-1-d-reclassification	CC-MAIN-2017-13	refinedweb	215	53.27
This is a tip about how I use Morris Pratt string searching algorithm in byte arrays to get the same efficient result. I'm assuming that you've understood the basic concept of this algorithm so it won't be repeated in this topic. Also, you should already know extension methods before you get started with this topic. In 2013, I built an extension method of Morris Pratt searching algorithm to search specific string in text file. But later, I had an idea and tried to apply it on every enumerable-related type if each element in it is equatable. So I expanded my method and then get the same efficient result if I search it in byte array, which means I can directly search string in raw text file and don't have to use ASCII or Unicode to decode it at first. The program became more efficient in text searching. It's easy to use these extensions. First of all, let's take a look of their prototypes: public static int MorrisPrattSearchFirst<T>(this T[] t, T[] p) where T : IEquatable<T> { } public static int MorrisPrattSearchFirst<T>(this T[] t, T[] p, int startIndex) where T : IEquatable<T> { } where t is the parent array and p is the specified array for searching. The second method allows users to search p in t starting at non-zero index. Constraint on type parameter T makes sure that each element in both arrays is equatable. Returned value represents the index of first matched result (-1 if not found). Both of them are defined under the CollectionAssistant.IEnumerableExtentions class. t p T -1 CollectionAssistant.IEnumerableExtentions Here's a complete example of using them. First, we search key word "Ishmael" in character arrays from the text file MobyDick.txt. And next search it in ASCII-encoded byte arrays. Then compare the efficiency. Ishmael using System; using System.Diagnostics; using System.IO; using System.Text; namespace CollectionAssistant.Demo { class Program { static void Main(string[] args) { // This is a example which demonstrates the differences // between searching text in characters and in raw byte-array. string keyWord = "Ishmael"; // Searching key word in character array. char[] originalCharArray = File.ReadAllText("MobyDick.txt").ToCharArray(); char[] keyWordCharArray = keyWord.ToCharArray(); int index = -1; int pos = 0; Console.WriteLine("Start searching key word in character array."); Stopwatch watch = Stopwatch.StartNew(); do { // Using the extension method. index = originalCharArray.MorrisPrattSearchFirst(keyWordCharArray, pos); if (index >= 0) { Console.WriteLine("Key word \"{0}\" found. Index: {1}", keyWord, index); pos += (index + keyWordCharArray.Length); } } while (index >= 0 && pos < originalCharArray.Length); watch.Stop(); Console.WriteLine("Elapsed ticks: {0}", watch.ElapsedTicks); Console.ReadKey(true); pos = 0; Console.WriteLine("Start searching key word in byte array."); // Searching key word in byte array. byte[] originalByteArray = File.ReadAllBytes("MobyDick.txt"); byte[] keyWordByteArray = Encoding.Default.GetBytes(keyWord); watch.Restart(); do { // Using the extension method. index = originalByteArray.MorrisPrattSearchFirst(keyWordByteArray, pos); if (index >= 0) { Console.WriteLine("Key word \"{0}\" found. Index: {1}", keyWord, index); pos += (index + keyWordByteArray.Length); } } while (index >= 0 && pos < originalByteArray.Length); watch.Stop(); Console.WriteLine("Elapsed ticks: {0}", watch.ElapsedTicks); Console.ReadKey(true); } } } The result shows that both of them performed almost same efficiently: about 3000 ~ 8000 ticks in this case. Searching text in character arrays and in byte arrays are both efficient while using Morris Pratt algorithm. But sometimes, it's better in byte arrays especially for some situations such as text file or multipart/form-data - which means parent byte array possibly contains both text and non-text data and can't be decoded into character array or string. You can obtain the complete source code from here. This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)	https://www.codeproject.com/Tips/729239/Using-Morris-Pratt-String-Searching-In-Byte-Arrays	CC-MAIN-2017-22	refinedweb	615	52.15
The classy prelude July 12, 2012 Michael Snoyman tl;dr: Announcing the beginning of classy-prelude, an alternate prelude which makes it easier to use conflicting names via typeclasses, and thereby encourages usage of more powerful libraries like text and unordered-containers. I'll release the code to Hackage, as soon as Hackage comes back up. A few months ago, Max Cantor braved the treacherous journey into the barren wastelands of northern Israel to pay me a visit /melodrama. We discussed a number of different ideas then, one of which being an alternate prelude. There have been a number of different alternate preludes attempted before, trying to do such things as fix the numeric type classes or automatically generate Javascript code. Our goal was entirely different. For me, it's based around a very simple idea: programmers are lazy. Let me give a practical motivating case. Suppose you're on line 247 of the file you're currently editing, and you need to modify some value wrapped in a Functor. You'd ideally like to write f <$> x. But have you imported Control.Applicative yet? If you want to write that "correct" code, you'll need to: - Scroll up to your import list. - Look for Control.Applicative. - If it's not there, type in import Control.Applicative ((<$>)). - Try to find where you were in the code. - Try to remember what you were doing. I'm sure I'm not the only Haskeller who has simply written fmap f x in this situation, even if we'd prefer the former. The solution to this is pretty simple: just export more common functions and operators. (While we're at it, we'll export common datatypes like ByteString.) But this is a relatively mundane problem. Let's look at some other very common cases: - Do you represent textual data with Stringor Text? The former lets you use ++, concat, and a bunch of other functions in the Prelude. The latter forces you to import qualified Data.Text as T, and then use T.appendand T.concat. - You need to build up a lookup table. Do you use Data.Mapor a simple associated list? This has important ramifications on program correctness, as the associated list approach doesn't promise you the same invariants as Data.Map. - If you want to start using conduit(or enumerator), you'll likely end up importing about 3 modules: the core module, one providing list-like primitives, another providing binary functions... and so on. Solution: type classes To sum up the problem more succinctly: we have too many name collissions. We deal with this via qualified imports, but this introduces a large number of import statements and tedious usage of module prefixes. So Max and I came up with a simple solution: just create typeclasses for these common, shared functions, and export them from a modified prelude. This means that your standard 20-odd line set of imports turns into: {-# LANGUAGE NoImplicitPrelude #-} import ClassyPrelude Wherever possible, we reuse existing typeclasses. For example, ++ is just an alias for Data.Monoid.mappend, and concat for Data.Monoid.mconcat. Since most of our common types ( String, Text, ByteString, Map, ...) provide Monoid instances, we immediately get a much more useful operator. In other cases, such as the length function, no such typeclass exists. For those cases, we define a new typeclass. The implementation is pretty simple in this case: class CanLength c i \| c -> i where length :: c -> i instance CanLength [a] Prelude.Int where length = Prelude.length instance CanLength ByteString Prelude.Int where length = S.length instance CanLength LByteString Int64 where length = L.length instance CanLength Text Prelude.Int where length = T.length instance CanLength (Map k v) Prelude.Int where length = Map.size instance CanLength (Set x) Prelude.Int where length = Set.size Notice the use of functional dependencies to state the datatype used to represent the length. I considered using type families, but believe that for our purposes here, the brevity of fundeps really pays off. This really shows in giving us relatively short error messages. Downsides There are of course some downsides to this approach. - As just mentioned: error messages are less helpful. - In some cases, explicit type signatures are necessary. For example, length . pack . "hello"is ambiguous, since lengthand packcould be working on either strict or lazy text, or a string, or possibly something else entirely. - Some seemingly simple functions (like map) need a bit more type machinery around them, as depending on the data structure in question, mapcan be more or less polymorphic. As a result of these, we think that classy-prelude is a good choice for experienced Haskellers looking to speed up their development time, not for beginners. It's best to get accustomed to the types available monomorphically first. A harder example To give an idea of some of the more complicated aspects here, let's take a complicated example: filter. We want to support filter for lists, ByteStrings, Maps, and even conduits. To see the problem, we need to look at the different type signatures: filter :: (a -> Bool) -> [a] -> [a] filter :: (Word8 -> Bool) -> ByteString -> ByteString filter :: (a -> Bool) -> Map k a -> Map k a filter :: Monad m => (a -> Bool) -> Conduit a m a To sum up: - For lists, Maps, and Conduits, the type of the predicate is polymorphic. For ByteString, it is always Word8. - For lists and Conduits, the input type and predicate type are the same. For Map, we have an extra type variable ( k). - For lists, ByteStrings, and Maps, there are two arguments, while for Conduits, there is only one. Said another way, the first three return a function, while the Conduitcase returns a Conduitvalue. So how do we represent these four different functions with a single typeclass? Firstly, we break it down into the part which is similar: each function takes a predicate a -> Bool and returns some value. So let's represent that with a typeclass: class CanFilter f a where filter :: (a -> Bool) -> f We don't want to get into undecidable or overloaded instances, so in order to handle lists, ByteStrings and Maps, we'll create another helper class that represents the case when filter returns a function: class CanFilterFunc c i \| c -> i where filterFunc :: (i -> Bool) -> c -> c Our functional dependency is essentially say "we have some container c which holds i, and only i." In theory we might want to get rid of that fundep, and then we could express things like "you can filter a ByteString like a collection of Word8s or a collection of Chars." However, I've opted to avoid such expressions for now. Next we need to provide an instance of CanFilter for instances of CanFilterFunc: instance (b ~ c, CanFilterFunc b a) => CanFilter (b -> c) a where filter = filterFunc This might be a bit surprising: why do we use b -> c instead of c -> c, and what's the purpose of b ~ c? The answer is that we're trying to help GHC with type inference. If we used c -> c, it would mean "here's an instance for when you want a function that takes c and returns c. What we're defining instead is an instance for any unary function, and then with the b ~ c equality constraint we're saying, "oh, and we only allow this to work if the input matches the output." This means that if GHC is only able to identify the type of either the input or the output, type inference still succeeds. Instances of CanFilterFunc are pretty simple; here are the three mentioned above. instance CanFilterFunc [a] a where filterFunc = Prelude.filter instance CanFilterFunc ByteString Word8 where filterFunc = S.filter instance Ord k => CanFilterFunc (Map k v) (k, v) where filterFunc = Map.filterWithKey . Prelude.curry Finally, our conduit instance: instance (Monad m, r ~ r') => CanFilter (Pipe l i i r m r') i where filter = CL.filter Again, we use the equality constraint trick to force the upstream and downstream result types to match. (If you haven't been following the recent conduit changes, don't worry about it.) Future changes I wrote the library so far by porting a project at work over to it, and adding in functionality as needed. I think this is the best approach to building up a useful prelude, and I'd like to ask others to help out in this as well. For now, it might be best to just copy in the ClassyPrelude module to your project and add things as necessary, and afterwards send a pull request. For immediate upcoming features, I'm planning on adding support for vector and unordered-containers datatypes, as well as aeson for JSON parsing. (Edit: I already added vector and unordered-containers support.) Max and I have also been discussing reversing the conduit/classy-prelude dependency, and providing instances in conduit itself. (Edit: For now, we have a separate classy-prelude-conduit package.) I'd like to hold off on that till classy-prelude stabilizes.	http://www.yesodweb.com/blog/2012/07/classy-prelude	CC-MAIN-2014-42	refinedweb	1,497	64.71
Welcome to part 3 of the the Flask 101 Series. - Flask 101: Create a Basic Python Web App - Flask 101: Add JSON to your Python Web App - Flask 101: Use HTML templates & send variables – This tutorial For this tutorial, we will create a random funny image + quote generator that you can refresh at will to lighten up your day. For a preview of the end result check the end of this tutorial 🙂 Also the full code for this project is available on my GitHub repo. 1 – Setup If you want to use a Python 3 virtual environment, you can follow this post for example. But all you really need is to install Flask # Install flask pip install flask Create the following directories and files, leave them empty for now. We fill fill them later. static/ templates/ myapp.py runapp.sh First things first, you will need to download some funny images into the static/ directory. I took mine from these 2 sites – businessinsider and honesttopaws – but of course feel free to use your own. For simplicity you can just download the ones on my GitHub repo here. 2 – Create a basic web page Inside the templates/ directory, create a file named index.html, with the contents below. This is a basic HTML web page that displays an h3 title and an image, with the exception of 2 things: - The content inside the <h3></h3> tags will be filled with a variable called random_quote, to be sent via your Flask app - The image inside img src is going to be a file under the ‘static’ directory you have created above, and the image filename will be specified by a variable called random_image, that is also going to be provided by your Flask app <!DOCTYPE html> <html> <body> <center> <h3>{{ random_quote }}</h3> <img src="{{url_for('static', filename=random_image)}}" /> </center> </body> </html> Now let’s see how your Flask application will send these variables to index.html. 3 – Create your basic flask application So far your directory structure should look like this static/ img1.jpg .. more images ... templates/ index.html myapp.py runapp.sh Now open the file named myapp.py that you have created above, and add the content below. We are basically doing 3 things there: - def random_jaden_quote() this function returns a random quote from Jaden Smith. I am not particularly a fan of Will Smith’s son, but during his teenage years, he published a series of quotes and tweets that are famous for making very little sense. I got mine from here. - def random_image() this one is in charge for returning one of the images inside your static/ directory at random - @app.route(‘/’) this is the main – and only – route of this app. It takes a random image, a random quote, and uses Flask’s render_template() function to send them to your index.html page from flask import Flask, render_template import os import random app = Flask(__name__) def random_jaden_quote(): """ return a random quote from Jaden Smith """ quotes = [ "Instagram is not the answer.", "You can discover everything you need to know about everything by looking at your hands", "Being born was the most influential thing that’s ever happened to me, for myself.", "When Life Gives You Big Problems, Just Be Happy You Forgot All Your Little Problems.", "The Lack Of Emotion In My Face Doesn't Mean I'm Unhappy.", "When The First Animal Went Extinct That Should've Been A Sign.", "How Can Mirrors Be Real If Our Eyes Aren't Real." ] quote = "%s -- Jaden Smith" % random.choice(quotes) return quote def random_image(): """ Return a random image from the ones in the static/ directory """ img_dir = "./static" img_list = os.listdir(img_dir) return random.choice(img_list) @app.route('/') def myapp(): quote = random_jaden_quote() image = random_image() return render_template('index.html', random_quote=quote, random_image=image) 5 – Test your app	https://naysan.ca/2020/11/28/flask-101-use-html-templates-send-variables/	CC-MAIN-2021-04	refinedweb	636	62.48
I got an error block in initialize: undefined method `SIGN' for Mineral:Class (NoMethodError) require "./mineral" . . . @map[x][y] = Mineral.SIGN class Mineral attr_accessor :x, :y, :cost, :SIGN @@SIGN = "s" def initialize(x, y) @x,@y = x,y @cost = rand 10 end end You need to define a getter method to access the class variables in class Mineral. The attr_accessor method does automatically define the getter and setter method for x, y, cost instance variables but there is no such facility for class variable. Besides, if @@SIGN is not a constant (expected to change at run-time), then I suggest that you use @@SIGN. Because, all capital named variables are constants in ruby - will raise error if attempted to change at run-time. class Mineral attr_accessor :x, :y, :cost @@sign = "s" def initialize(x, y) @x,@y = x,y @cost = rand 10 end def self.get_sign @@sign end end Further, you can access the @@sign as: require "./mineral" . . . @map[x][y] = Mineral.get_sign From your question it feels that you will benefit by clearing concepts of class and instance variables and methods in ruby. A good starting point is this. Comment if you still have doubt or confusion, will be glad to clear it. Hope it helps : )	https://codedump.io/share/BV88V4ZoW7bD/1/ruby---block-in-initialize39-undefined-method	CC-MAIN-2017-39	refinedweb	207	62.27
I have a WCF service defined as the following: namespace M1.FileUploader.Web { // NOTE: You can use the "Rename" command on the "Refactor" menu to change the class name "UploadService" in code, svc and config file together. public class UploadService : IUploadService { public void UploadFile(Stream uploadStream) { string filePath = Path.Combine(@"C:\Temp\Uploads", Guid.NewGuid().ToString()); FileStream fileStream = File.Open(filePath, FileMode.Create, FileAccess.Write); byte[] buffer = new byte[1024]; int bytesRead = 0; while (true) { bytesRead = uploadStream.Read(buffer, 0, buffer.Length); if (bytesRead == 0) { break; } fileStream.Write(buffer, 0, byte View Complete Post View Complete Post This month's column answers frequently asked questions about implementing REST. Jon Flanders MSDN Magazine July I am working on my company's intranet which runs on sharepoint. Right now, very few people have uploaded their pics into their MYSITE. I know this can be done by logging in into the SSP, but I need a HR representative to upload the photo and they should not have access to the SharePoint server. Are there any free web parts that I can install, that will give the HR rep to upload the photo..and then..it will automatically appear in the staff's MYSITE The REST Starter Kit was targeted at WCF 3.5. I am wondering if it is still needed with WCF 4? Hall of Fame Twitter Terms of Service Privacy Policy Contact Us Archives Tell A Friend	http://www.dotnetspark.com/links/26739-uploading-via-rest.aspx	CC-MAIN-2017-13	refinedweb	236	65.62
On Tue, 2017-10-03 at 12:40 -0500, Eric W. Biederman wrote:> Jürg Billeter <j@bitron.ch> writes:> > What's actually the reason that CLONE_NEWPID requires CAP_SYS_ADMIN? > > Does CLONE_NEWPID pose any risks that don't exist for> > CLONE_NEWUSER\|CLONE_NEWPID? Assuming we can't simply drop the> > CAP_SYS_ADMIN requirement, do you see a better solution for this use> > case?> > CLONE_NEWPID without a permission check would allow runing a setuid root> application in a pid namespace. Off the top of my head I can't think of> a really good exploit. But when you mess up pid files, and hide> information from a privileged application I can completely imagine> forcing that application to misbehave in ways the attacker can control.> Leading to bad things.Could we allow unprivileged CLONE_NEWPID if the no_new_privs bit isset?Jürg	http://lkml.org/lkml/2017/10/3/773	CC-MAIN-2018-13	refinedweb	134	67.55
Python sys Module – Important Functions Stay updated with the latest technology trends while you're on the move - Join DataFlair's Telegram Channel 1. Objective In our last Python tutorial, we discussed Python Subprocess. Today, we will discuss Python sys Module. Moreover, we learn about functions like version, displayhook, stderr, and more. Also, we will see how to import sys in Python. So, let’s start the Python sys Module tutorial. 2. What is Python sys Module? Let’s get to know it first. The sys module in Python lets us access system-specific parameters and functions. It gives us information about constants, functions, and methods of the interpreter. To find out more about it, you can try one of two functions: - Summarized information- constants, functions, methods: >>> dir(sys) - Detailed information- >>> help(sys) Some things you can do with it are: You must take a look of Python os Module >>> import sys #Get version information >>> sys.version ‘3.7.0 (v3.7.0:1bf9cc5093, Jun 27 2018, 04:06:47) [MSC v.1914 32 bit (Intel)]’ >>> sys.version_info sys.version_info(major=3, minor=7, micro=0, releaselevel=’final’, serial=0) >>> sys.getrecursionlimit() #Get maximal recursion depth 1000 >>> sys.setrecursionlimit(1500) #Set maximal recursion depth >>> sys.getrecursionlimit() 1500 Let’s revise CGI Programming in Python with functions 3. Command-line Arguments in Python sys Module We can store the command-line arguments we pass to a script in a list we call sys.argv. The first item of this is the name of the script; the arguments are next. Save the following code in a script: import sys print(sys.argv) for i in range(len(sys.argv)): if i==0: print("The function is",sys.argv[0]) else: print("Argument:",sys.argv[i]) C:\Users\Ayushi\Desktop>py sysdemo.py 2 3 [‘sysdemo.py’,’2’,’3’] The function is sysdemo.py Argument:2 Argument:3 4. Changing the Output Behavior of the Shell We’ve so often used the Python shell interactively and even as a calculator. But what if we wanted to change how it delivers the output? Well, we can; we simply rebind sys.displayhook to a callable object. Let’s revise Python Zipfile >>> import sys >>> x=42 >>> x 42 >>> print(x) 42 >>> def show(x): print("Output:",x) >>> sys.displayhook=show >>> x Output: 42 >>> print(x) 42 Output: None 5. Ways to Read and Write in Python sys Module We can also use the readline() method to get input from the user: Do you know about Python array Module >>> print("Type in value: ",sys.stdin.readline()[:-1]) 23 Type in value: 23 The following piece of code lets us print to the screen: >>> sys.stdout.write('Way to write') Way to write12 >>> sys.stdout.write('Way to write\n') Way to write 13 Notice that it gives us the number of characters, which is why it gives us 13 instead of 12 when we give it a \n newline character too at the end. 6. Getting Names of Modules sys.modules in Python gives us a dictionary of the names of the modules existing in the current shell. >>> import sys >>> sys.modules 7. Investigating the Path in Python sys Module sys.path in Python will give you a list of paths it will search in whenever you make an import. You must read about Python Packages >>> sys.path [”, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\Lib\\idlelib’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\python37.zip’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\DLLs’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\lib’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\lib\\site-packages’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\lib\\site-packages\\scrapy-1.5.1-py3.7.egg’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\lib\\site-packages\\service_identity-17.0.0-py3.7.egg’, ‘C:\\Users\\Ayushi\\AppData\\Local\\Programs\\Python\\Python37-32\\lib\\site-packages\\parsel-1.5.0-py3.7.egg’] You can add a path to this with the append() method- >>> sys.path.append('C:\\Users\\Ayushi\\Desktop') Now, when you make a call to sys.path in Python, you can see this location in the list. Have a look at Python Modules vs Packages 8. Getting the Copyrights in Python sys Module sys.copyright in Python displays the copyright information on the currently-installed version of Python. >>> print(sys.copyright) Let’s revise the Python Datetime Module 9. Exiting Current Flow of Execution in Python sys Module sys.exit in Python lets the interpreter abruptly exit the current flow of execution. >>> sys.exit You can use a try-except block to catch this call- >>> try: sys.exit(1) except SystemExit: pass 10. Getting Reference Count and Platform The getrefcount function gives us the count of references to an object where used. When in a program, this value drops to 0, Python cleans up the memory for this variable. Let’s take an example. Have a look at the Python Multiprocessing Module >>> a=7 >>> sys.getrefcount(a) 37 To get the name of the platform we’re running Python on, we make a call to sys.platform in Python: >>> sys.platform ‘win32’ 11. Redirecting Output in Python sys Module Instead of delivering the output to the console, you can log into a text file. >>> import sys >>> print('Hello') #Prints normally Hello Let’s revise deep and shallow copy in Python >>> saveout=sys.stdout >>> fsock=open('out.log','w') >>> sys.stdout=fsock >>> print('Message to log') >>> sys.stdout=saveout >>> fsock.close() 12. Redirecting Error Information in Python sys Module Using sys.stderr and a text file in Python, we can log error information to the text file. See how: >>> import sys >>> fsock=open('error.log','w') #Opening the file >>> sys.stderr=fsock #Redirecting standard error by assigning file object of file to stderr >>> raise Exception('this is an error') >>> fsock.close() Note that this traceback doesn’t show up in the log file until we close its file object in Python (which, in this case, is fsock). Read – Python Assert Statements Another way we use sys.stderr is as follows: >>> for i in range(3): sys.stderr.write('Hello') Hello5 Hello5 Hello5 Unlike stdout, stderr does not add carriage returns. A similar function flush() lets us flush write buffers. 13. More Functions in Python sys Module The purpose of this tutorial is to get you started with the sys module; there is so much more to it. Let’s discuss Python Unit Testing To get a list of all the built-in functions and methods we have for sys, try the calling the dir() function on it. Try them out, won’t you? So, this was all in Python sys Module. Hope you like our explanation. 14. Conclusion – sys Module in Python Hence, today in this Python sys module tutorial, we took a brief look at various functions and methods available with the Python sys module, including argv, stdin, stdout, stderr, setrecursionlimit, and exit. We also discussed the meaning of import sys in Python. Still, if you have any doubt regarding Python sys Module, ask in the comment tab. See also – Python Collection Module For reference	https://data-flair.training/blogs/python-sys-module/	CC-MAIN-2019-51	refinedweb	1,216	59.9
A Simple Extractive Summarisation System This post talks you through the code of a simple extractive summarisation system written in Python. There was a bit of interest in a summariser posted to reddit a few days ago, which inspired me to do some tinkering. I’ve never really engaged with the extensive summarisation literature, and I doubt I’ll be publishing in it anytime soon. I mostly built this for fun, and to teach myself a little about publishing an application with django and Google App Engine. The system can be found at (at least while I’m within my free quota). The version at app engine is slightly different from the one described below, as I’ve added a few optimisations to fit within the memory limit and make my CPU time stretch a little further. You can find a version of the GAE ready code here, under the FreeBSD license. Overview We can divide the system into three basic components: - Text pre-processor. This handles things like dividing the document into sentences, dividing the sentences into words, normalising away suffixes, eliminating common words, etc. - The sentence selector. This is the engine of the system. We will base our selection criteria on word frequencies. This is a common starting point for many NLP tasks. - Sentence sorter. This sorts the selected sentences to produce a pleasing summary. We will simply order the sentences by their position in the document. The Summariser Class class Summariser(object): def __call__(self, doc, n): """ Return the N most pertinent sentences of a document, in the order in which they occur """ # A 'bag-of-words' is a sparse vector # of token frequencies. docBow = doc.bagOfWords # Get N most similar. topN = sorted(doc, key=lambda s: self.similarity(docBow, s.bagOfWords))[-n:] # Sort back into document order. return sorted(topN, key=lambda s: s.position) def similarity(self, docBow, sentBow): # Sum the frequencies of each token in the sentence # in the rest of the document return sum((docBow[t]-f)f for t, f in sentBow.items()) The Summariser.__call__ function takes the processed document and performs two sorts, trimming the document down to N sentences after the first sort by similarity. The similarity score for each sentence is defined as the sum of the frequency of its words in other sentences of the document. We exclude the sentence itself, so that we avoid selecting long sentences that contain terms not in the rest of the document. The idea here is to find sentences that are prototypical of the document — that is, the most like the rest of the document, in terms of their word frequency distribution. Pre-processing with nltk The summariser expects the document to have the text divided into sentences, the sentences divided into words, and word frequencies counted within both. To do this, we call some functions from nltk The pre-processing stage takes the document from a raw string to a list of sentences, each of which contains a list of tokens. We will also index the tokens in the document into a “bag-of-words”: a sparse vector that stores each word’s frequency. This is implemented as a defaultdictionary. The Document and Sentence classes look like this: from collections import defaultdict from nltk.tokenize import sent_tokenize as sent_tokenise from nltk.tokenize import word_tokenize as word_tokenise class Document(list): def __init__(self, kwargs): """ Build a list of sentences and a bag of words """ list.__init__(self) if 'text' in kwargs: text = kwargs.pop('text') elif 'url' in kwargs: text = self._urlToText(kwargs.pop('url')) else: raise StandardError, "Document requires text or url" assert not kwargs bow = defaultdict(int) for i, sentenceStr in enumerate(sent_tokenise(text)): sentence = Sentence(sentenceStr, i) self.append(sentence) for k, v in sentence.bagOfWords.items(): bow[k] += v self.bagOfWords = bow class Sentence(list): def __init__(self, sentenceStr, position): self.string = cgi.escape(sentenceStr) # Lowercase the first word if sentenceStr[0].isupper(): letters = list(sentenceStr) letters[0] = letters[0].lower() sentenceStr = ''.join(letters) tokens = word_tokenise(sentenceStr) bow = defaultdict(int) for token in tokens: # Normalise for morphology and case, # and exclude common words term = standardise(token) if term: bow[term] += 1 self.append(term) self.bagOfWords = bow self.position = position All the real work here is done by the nltk Punkt sentence boundary detector, and the tokeniser. These tasks aren’t that interesting, but they’re surprisingly hard to get just right. Sentence boundary detection is a good example of this: good solutions are much more complicated than you might think. I would advise against rolling your own sentence boundary detector with a regular expression, for the same reason regular expressions are a poor choice for parsing html: it’s an error-prone strategy that’s fundamentally not powerful enough for the task. Use the good solutions that work right out of the box. Speaking of html parsing, the process that extracts text from web pages is, in my opinion, the weakest part of the system. I’d really appreciate feedback on a better way to do this. The function looks like this: whiteRE = re.compile(r'\s+') constraintsRE = re.compile(u'^[^\u2022]\|[.!?]$') def _urlToText(self, url): """ (Terrible) text extraction using that ugly swamp BeautifulSoup """ page = urllib2.urlopen(url) soup = BeautifulSoup(page) body = soup.findAll('body') body = body[0] if body else soup parElements = [p for p in body('p') if not p.attrs] brPars = [p for p in body(True) \ if p('br', recursive=False)] for node in brPars: for par in node.fetchText(True, recursive=False): parElements.append(par) paragraphs = [] for paragraph in parElements: if isinstance(paragraph, unicode): text = paragraph else: text = ' '.join(paragraph.fetchText(True)) text = self.whiteRE.sub(' ', text.strip()) if self.constraintsRE.search(text): paragraphs.append(text) title = soup.find('title').string return title, '\n'.join(paragraphs) This method looks for text under p elements, and text that is the sibling of br elements. A few ad hoc constraints were added from manual testing. This is the part of the program I’m least happy with, and I’d love to hear about a more principled solution to finding the body text of an arbitrary page. I’m also quite unhappy with the implementation. Initially I wrote this with pyquery instead of BeautifulSoup, but Google App Engine does not support lxml. Boo and hiss by starring this issue. I really don’t like BeautifulSoup. It’s slow, and I find the maze of aliases in the interface incredibly annoying. Addressing Zipf’s Law The pre-processing and summarisation code presented so far is enough to do the job. However, we can improve the accuracy of the summariser by writing in just a touch more linguistic sensitivity. Most words in a language are rare, which can be problematic when your application works by counting word frequencies. To be more precise, word frequencies follow a power law distribution, an observation known as Zipf’s law. This means that our frequency distributions will generally be quite sparse, making lexical frequencies less meaningful. There are a few standard tactics we can deploy to address this. Standardising Word Forms The first set of tweaks are stemming, stopping and case normalisation — processes I collectively refer to as “standardisation”. Stemming is the removal of inflexional and derivational suffixes. For instance, both archeologist and archeology would get stemmed to archeolog. This might look weird, but it means the terms will match, allowing us to count them together as one term. Stemming loses some precision, but on the whole it’s often beneficial when you’re trying to model the document’s topic. I used the nltk implementation of Porter‘s algorithm. The (ugly) source for this can be viewed here. Stopping addresses the other side of the problem caused by the unbalanced frequency distribution of words. Grammatical terms, such as “the” and “of”, are far more frequent than the interesting content words. It is therefore useful to discard them from our counts. I do this with the stop list provided with nltk. Finally, another possibility is to normalise away case variation. I’ve chosen not to do this, because I don’t want to confuse proper nouns with common nouns. Instead I just lower case the first word of the sentence. This will be wrong for sentences that start with proper nouns, but I didn’t want to use a more complicated process, such as part-of-speech tagging. I implement the standardise processes as a private class inside a module, with only an instance made public.. This centralises them, so that I can be sure all tokens are being standardised in the same way. import _stops import nltk.stem.porter as _porter class _Standardise(object): def __init__(self): self.stemmer = lambda word: word self.stopWords = {} self.lower = False def __call__(self, string): if string.lower() in self.stopWords: return None if self.lower: string = string.lower() stemmed = self.stemmer(string) return stemmed def config(self, kwargs): stemmer = kwargs.pop('stemming') if stemmer == 'porter': self.stemmer = _porter.PorterStemmer().stem_word else: raise StandardError, "Unknown stemmer", stemmer if kwargs.pop('stopping'): self.stopWords = _stops.nltkStops self.lower = bool(kwargs.pop('lower')) standardise = _Standardise() TF-IDF Weighting There’s actually a way that we can use the imbalanced frequency distribution of word occurrences to our advantage, to discover what a document is really about more reliably. Imagine we have a document where two words occur 5 times each: professional and archeologist. It seems reasonable to assume that archeologist is a much stronger clue about the document’s topic, and we should weight sentences that contain this word higher so that hopefully they make it into the summary. The reason archeologist is a better indication is that we are more surprised to see it. What we want, then, are statistics about how often a word appears in the language as a whole. Word which are rare overall will be weighted highly; words which are common will receive a low weight. This is called TF-IDF weighting, for term frequencyinverse document frequency. The weight is calculated by taking the log of the inverse percentage of documents in a sample that the word has occurred in. I used a sample of 800,000 pages from the English Wikipedia to determine the document frequencies. The log is taken to avoid having the IDF part dominate the term frequency part. Consider that we would be weighting single occurrence words by 800,000 if we used a linear weight. Apart from some boring code to read in the document frequencies and turn them into IDF weights, the TF-IDF weighted summariser simply overrides the similarity method of the Summariser: class TFIDFSummariser(Summariser): """ Scores sentences by TF-IDF weighted token frequencies """ def __init__(self): Summariser.__init__(self) # The number of documents the frequencies were drawn from. n = 818741.0 self.idfs = self._loadIDFs(n) def _loadIDFs(self, n): dfLoc = localPath('wiki_doc_freqs.txt') dfs = collections.defaultdict(int) # Convenience for codecs.open. lines = utf8open(dfLoc).read().strip().split('\n') # Read in the document freqs. # Have to do this first because we collapse some freqs # through standardisation. for line in lines: token, freq = line.split('\t') token = standardise(token) if token: dfs[token] += int(freq) # Turn the frequencies into IDF weights. idfs = collections.defaultdict(float) for token, freq in dfs.items(): idf = log(n/freq, 10) idfs[token] = idf return idfs def similarity(self, docBow, sentBow): idfs = self.idfs # Apply the IDF weight to each term. return sum([f(docBow[t]-f)idfs[t] for t, f in sentBow.items()]) This is a little less efficient than applying the IDF weights to the document vector directly, since we may have to weigh the same term multiple times for different sentences. However, I doubt this will make much difference to overall running time, and it allows a design I think is a little nicer, as the variation is confined to the similarity method. That’s it for now… Well, that’s the simple extractive summariser, and a tweaked one with TF-IDF. If there’s sufficient interest, I’ll follow this up with a little evaluation experiment. Summarisation is difficult to evaluate, because quality is subjective, but I have a plan for what seems to me to be a reasonable approximation. 8 Comments » Recent Links Archives - September 2013 (1) - November 2009 (1) Categories RSSEntries RSS excellent article! Hi, I just want to let you know that it doesn’t work for It outputs the url 1 char per line. However congratulations on this excellent article Thanks. I was passing the wrong arguments to the template on parse errors. Wonderful! Perhaps there’s a good metric of summarization quality somewhere [...] A Simple Extractive Summarisation System « Computational Linguistics (tags: language programming) [...] Pingback by Knowtu » links for 2009-11-23 \| 2009/11/24 \| Nice article! As a possible solution for _urlToText(), you can use: pageText = soup.findAll(text=True) Honnibal thank you for taking time to write for us. Here’s a possibly interesting alternative to _urlToText() that I have been using: You will probably need BeautifulSoup 3.0.4 as later version break soup2text.py but it’s well worth it as the success rate is very decent! Once I have my text soup, I find paragraphs by splitting a string using the delimiter “\n\n” (as created by soup2text.py) and then find lines which are longer than 15 characters and compare them against a list of nonos, here’s the actual code: Cheers! Nice Article. Keep up the gud work. Looking for more such informative article.	http://honnibal.wordpress.com/2009/11/18/a-simple-extractive-summarisation-system/	CC-MAIN-2014-10	refinedweb	2,253	57.67
How to create closure in Groovy Closure is an amazingly powerful programming tool, most tricks you can do in a functional language based on closure. To put it simple, closure is a function without name. Its a value, just like normal variable, can be associate with any valid variable name. You can assign it to local variable name, pass it as parameter, return it from a function. myClosure = { arg1 , arg2 -> println arg1 println arg2 } A closure is the same as any normal function except the way of the parameter declaration. In Groovy , parameter list and function body divided by "->" operator. It looks like an arrow, means send the parameter to function body. There are a lot of ways to call the closure. myClosure 'hello', 'world' myClosure.call('hello', 'world') myClosure('hello', 'world') myClosure.doCall('hello', 'world') Pass closure as parameter or return from function. def foo( closure ) { closure('hello','world') closure } foo(myClosure) foo(myClosure)('return', 'value') But the most used form is the following. foo { arg1 , arg2 -> println arg1 println arg2 } list = [3,4,5] list.each { it -> println it } In Javascript, the inner function can reference the variable that defined in its parent function. Groovy closure is just like that. def bar () { local = 'I am local' localClosure = { it -> println it println local } localClosure } bar()('hello')	http://makble.com/how-to-create-closure-in-groovy	CC-MAIN-2022-40	refinedweb	217	58.58
noqiflush, qiflush - enable/disable queue flushing #include <curses.h> void noqiflush(void); void qiflush(void); The qiflush() function causes all output in the display driver queue to be flushed whenever an interrupt key (interrupt, suspend, or quit) is pressed. The noqiflush() causes no such flushing to occur. The default for the option is inherited from the display driver settings. These functions do not return a value. No errors are defined. Calling qiflush() provides faster response to interrupts, but causes Curses to have the wrong idea of what is on the screen. The same effect is achieved outside Curses using the NOFLSH local mode flag specified in the XBD specification (General Terminal Interface). Input Processing, intrflush(), <curses.h>, XBD specification, Parameters that Can be Set (NOFLSH flag).	http://pubs.opengroup.org/onlinepubs/007908775/xcurses/noqiflush.html	CC-MAIN-2015-22	refinedweb	126	50.73
Chanukah is coming soon! So I thought it would be a great idea to make a project relating to the holiday. I made this cool Chanukah Menorah with an Arduino that plays a different song each time you change the night by pressing the button. The LEDs flicker similar to a flame on a candle. I found the songs for the Menorah by finding MIDI files of the song and using an online tool to convert it to an Arduino tone code. Step 1: Parts/Materials Switch to each picture to see what part it is. Hover your mouse over each object. Step 2: Cut the LEDs Cut 8 of the 9 LEDs about half way leaving one LED uncut. The uncut LED be the Shamash (The taller candle in the middle). Step 3: Put the LEDs Into the Breadboard Next, put the LEDs into the breadboard and place them equidistance from each other(every LED should have the same amount of distance between each other). I placed each LED 2 pins/holes between each other. Each side should have 4 LEDs with the Shamash (tallest LED) In the middle separating the two sides. Step 4: Place a Short Piece of Wire Connecting Each Ground Pin to the Ground Bar Place a short piece of wire connecting each ground pin of every LED to the Ground Bar (Usually marked in Blue). Step 5: Connect the Ground and Positive Rails to 5v (5 Volts) and GND (Ground) Take two wires and connect the bar marked in red to the 5v Pin and the Ground rail to the ground pin (GND) on the Arduino. Step 6: Connect Each LED to Their Proper Pin Connect each LED to their specific numbered pin on the Arduino. This time your connecting the LED's other pin (NOT GROUND) to the corresponding pins on the Arduino. NOTE as you go from right to left the pin numbers decrease. The first LED (It starts on the right side) goes to pin 13 the next to pin 12, then 11, 10 ,9 8, 7, 6 and 5 should be the last pin for the last LED (All the way at the end of the left side) Your LED Menorah should look something like the last image of this step with all of the wires connected up. Step 7: Next Place the Button on the Breadboard Next, place the button on the breadboard making sure that one side of the pins is on one side of the breadboard while the other pins are on the other side of it. Step 8: Connect a Resistor Up to the Button Connect a resistor up to the lower right side of the button with the other leg of the resistor going to another column on the breadboard. Step 9: Connect the Resistor to 5v and the Button to Ground Take a wire (The red wire in the image) and connect it to the same column as the other side of the resistor. Connect the other side of that wire (The red wire in the image) to the 5v rail (The red one). Then take another wire (It is the black wire in the photo) and connect it to the top left side of the button and connect the other side of that wire to the ground rail (The blue one). Step 10: Connect Button to Pin 2 on the Arduino Now, connect a wire between the top right pin of the button (The green wire in the photo) to pin 2 on the Arduino Step 11: Connect the Speaker Next, connect one wire of the the speaker to pin 4 and the other to ground on the Arduino. NOTE if you are building this with a piezo buzzer and not a speaker, then you must take note of which wire goes to ground and which goes to pin 4. Step 12: Time to Program the Arduino After you completed all the previous steps your Menorah should look something similar to this. Now to program the Arduino you must make sure you have Arduino installed on your computer. If you don't have it you can download Arduino from their website Next download the code file Menorah2.ino from the download button bellow and open it on Arduino. Upload the code to the Arduino and test out your Menorah! Step 13: Conclusion Now you can power your Musical Menorah using batteries or over a usb port. Enjoy your new Musical Menorah 14 Discussions 13 days ago Very cool idea! How do I change the music to diffrent songs? Question 21 days ago on Introduction is it safe to connect a led directly to digital output without a resistor ? Answer 19 days ago I think you'll burn them out. I used a 220-ohm resistor for each light. Reply 19 days ago Hi Elen - I agree with you , yet Jercool didn’t use any resistor ... I guess Arduino May have a current limiter in the digital outputs ... Reply 19 days ago Without a resistor you can burn out LEDs with Arduino. Best to use a resistor. 25 days ago Thanks so much! I love this. I changed the code a little so that the next song only goes on when you push the button. I may try to figure out how to add an interrupt so I can skip to the next song if I want. I'm going to wire it into a 3D printed menorah. 26 days ago I might be doing something wrong but I can't get it to go to any number of counts besides 1. Any ideas? 11 months ago Very slick! Now I just want to make one out of LEGOs... Reply 10 months ago That is posible. There are many ways to integrate electronic projects with Legos. 1 year ago Thank you so much! One of my colleagues at work is Jewish and doesn't have anything with which to decorate his desk this season. I decided I would make him a arduino menorah and, while searching for ideas, came across your instructable. I made some minor code tweaks I thought I'd share. I'm by no means an expert programmer so just my 2c. I added in pRNG to flicker the Shamash: #include "pRNG.h" pRNG prng; I made an array of the LED pins: const int ledPins[] = {13, 12, 11, 10, 8, 7, 6, 5}; and streamlined the loop: void loop() { buttonState = digitalRead(buttonPin); byte flick1 = prng.getRndByte(); analogWrite(9, flick1); if (buttonState == LOW) { count++; digitalWrite(ledPins[count-1], HIGH); midi(count); } if (count == 9) { count = 0; for (int i = 0; i <= 7; i++){ digitalWrite(ledPins[i], LOW); } } } As you can tell with the song call, I combined all the songs into one midi sub and passed it the count. Within that function, I check the integer and play the required song. I'll try to post a pic of my finished design after this weekend. It's just breadboarded right now. I'm also hoping to migrate to a smaller chip to save my Uno, haha. YOU SAVED ME HOURS ON THOSE MIDIS! 1 year ago Top level instructable very clear Reply 1 year ago Thanks 1 year ago Fun idea. And you don't have to worry about fire hazards. Reply 1 year ago True i didn't think about that lol.	https://www.instructables.com/id/Musical-Menorah-made-With-Arduino/	CC-MAIN-2018-51	refinedweb	1,232	78.38
Now in section Inheritance mainly in Hiding And Overriding Methods can we predict the output of the following program? also read: class HidePoint { int x = 0, y = 0; void move(int dx, int dy) { x += dx; y += dy; } int getX() { return x; } int getY() { return y; } int color; } class HideRealPoint extends HidePoint { float x = 0.0f, y = 0.0f; void move(int dx, int dy) { move((float)dx, (float)dy); } void move(float dx, float dy) { x += dx; y += dy; } int getX() { return (int)Math.floor(x); } int getY() { return (int)Math.floor(y); } } public class HidingOverridingExample { public static void main(String[] args) { HideRealPoint rp = new HideRealPoint(); HidePoint p = rp; rp.move(1.71828f, 4.14159f); p.move(1, -1); show(p.x, p.y); show(rp.x, rp.y); show(p.getX(), p.getY()); show(rp.getX(), rp.getY()); } static void show(int x, int y) { System.out.println("(" + x + ", " + y + ")"); } static void show(float x, float y) { System.out.println("(" + x + ", " + y + ")"); } } It Prints: (0, 0) (2.7182798, 3.14159) (2, 3) (2, 3) Here the overriding methods getX and getY in class RealPoint have the same return types as the methods of class Point that they override, so this code can be successfully compiled. The first line of output illustrates the fact that an instance of RealPoint actually contains the two integer fields declared in class Point; it is just that their names are hidden from code that occurs within the declaration of class RealPoint (and those of any subclasses it might have). When a reference to an instance of class RealPoint in a variable of type Point is used to access the field x, the integer field x declared in class Point is accessed. The fact that its value is zero indicates that the method invocation p.move(1, -1) did not invoke the method move of class Point; instead, it invoked the overriding method move of.	http://javabeat.net/hiding-and-overriding-methods-in-java/	CC-MAIN-2017-04	refinedweb	321	69.62
JVM Internals: Memory Overview Stephen O'Brien Updated on ・12 min read Introduction This was originally posted on my own blog a few years back, but I'd rather continue the series here, so, re-posting. What is this post about? The goal of this post is to give an overview of the heap and non-heap memory regions of the JVM - with some small introduction to both - and also to show what happens in the event of a heap/non-heap memory issue within a docker container. I assume some basic knowledge of Java, the JVM, docker and linux. You will need docker and openjdk 8 installed on a linux system (I used ubuntu 16.04 to write this post). Containerizing a java app To start I'm going to keep things super simple. Let's build a program which prints "Hello world!" and waits forever: // HelloWorld.java public class HelloWorld { public static void main(String[] args) throws Exception { System.out.println("Hello world!"); System.in.read(); } } Now, a simple Dockerfile: FROM openjdk:8-jdk ADD HelloWorld.java . RUN javac HelloWorld.java ENTRYPOINT java HelloWorld With that we can build and launch our application in a container: $ docker build --tag jvm-test . $ docker run -ti --rm --name hello-jvm jvm-test Hello world! You can use CTRL-C to kill the container when you are done. Right, now we have a simple program running, what can we do? Let's analyze the JVM. Basic JVM analysis Lets get a list what objects we have on the heap within our application. First, get into the container (assuming it's still running from above) and get the JVM processes PID. $ docker exec -ti hello-jvm bash root@5f20ae043968:/ $ ps aux\|grep [j]ava root 1 0.1 0.0 4292 708 pts/0 Ss+ 12:27 0:00 /bin/sh -c java HelloWorld root 7 0.2 0.1 6877428 23756 pts/0 Sl+ 12:27 0:00 java HelloWorld From the above, we see the PID is 7. For analysis, the openjdk comes with a number of tools. jmap is one such tool which allows us to view heap information about a JVM process. To get a list of objects, their number of instances and the space they take up in the heap you can use jmap -histo <JVM_PID>. root@5f20ae043968:/ $ jmap -histo 7 num #instances #bytes class name ---------------------------------------------- 1: 422 2256744 [I 2: 1600 141520 [C 3: 364 58560 [B 4: 470 53544 java.lang.Class 5: 1204 28896 java.lang.String 6: 551 28152 [Ljava.lang.Object; 7: 110 7920 java.lang.reflect.Field 8: 258 4128 java.lang.Integer 9: 97 3880 java.lang.ref.SoftReference 10: 111 3552 java.util.Hashtable$Entry 11: 133 3192 java.lang.StringBuilder 12: 8 3008 java.lang.Thread 13: 75 2400 java.io.File 14: 54 2080 [Ljava.lang.String; 15: 38 1824 sun.util.locale.LocaleObjectCache$CacheEntry 16: 12 1760 [Ljava.util.Hashtable$Entry; 17: 55 1760 java.util.concurrent.ConcurrentHashMap$Node 18: 27 1728 java.net.URL 19: 20 1600 [S ... 222: 1 16 sun.reflect.ReflectionFactory Total 6583 2642792 As you can see above there are 6583 instances of a mixture of 222 different classes, taking up over 2.6MB of the heap, for our simple HelloWorld program! When I first saw this it raised a lot of questions - what is [I, why is there a java.lang.String and a [Ljava.lang.String? What are all these classes? The single letter class names you see above are all documented under Class.getName(). If you look back to the jmap output, the first few instances all have [ prefixing them - e.g. [I. [ denotes a 1 dimensional array of the type proceeding it - [I denotes an array of int e.g. new int[3]. [[I denotes a 2D array, new int[2][3] and so on. Also in the jmap output above were instances of [L.java.lang.String which is just an array of String's - new String[3]. To see this for yourself: // InstanceName.java public class InstanceName { public static void main(String[] args) throws Exception { int[] is = new int[3]; System.out.println(is.getClass().getName()); boolean[][][] bs = new boolean[2][5][4]; System.out.println(bs.getClass().getName()); String[] ss = new String[3]; System.out.println(ss.getClass().getName()); } } Compiling and running this we get: $ javac InstanceName.java $ java InstanceName [I [[[Z [Ljava.lang.String; That's a quick overview of one way to look at what's loaded on the heap. I mentioned other memory regions in the JVM earlier, what are these? Heap and Non-Heap memory The JVM can be divided into many different memory segments (segments/regions/areas, I'll use these words interchangeably, but generally they mean the same thing), if we take a high level view first we have two segments - memory used for objects on the heap and non-heap memory. If we zoom in, the heap has different areas within which we can talk about, depending on what we want to discuss - there is the Eden space, where most new objects are initially created, the Survivor space, where objects go if they survive an Eden space garbage collection (GC) and the Old Generation which contains objects that have lived in Survivor space for a while. Specifically, it contains objects that have been initialized - e.g. List<String> s = new ArrayList<String>(); will create an ArrayList object on the heap, and s will point to this. In the previous section I ran through what objects are loaded into the heap for our HelloWorld program, so what about non-heap memory? Non-Heap Memory If you have ever written a non-trivial java application with jdk8 you have probably heard of Metaspace. This is an example of non-heap memory. It's where the JVM will store class definitions, static variables, methods, classloaders and other metadata. But there are many other non-heap memory regions the JVM will use. Let's list them! To do so, first we need to enable native memory tracking in our java app: FROM openjdk:8-jdk ADD HelloWorld.java . RUN cat HelloWorld.java RUN javac HelloWorld.java ENTRYPOINT java -XX:NativeMemoryTracking=detail HelloWorld Now build and re-run: $ docker build --tag jvm-test . $ docker run -ti --rm --name hello-jvm jvm-test Hello world! In another terminal, exec into the container and get a summary of overall memory usage with jcmd's VM.native_memory command: $ docker exec --privileged -ti hello-jvm bash root@aa5ae77e1305:/ $ jcmd 33 sun.tools.jcmd.JCmd 7 HelloWorld root@aa5ae77e1305:/ $ jcmd 7 VM.native_memory summary 7: Native Memory Tracking: Total: reserved=5576143KB, committed=1117747KB - Java Heap (reserved=4069376KB, committed=920064KB) (mmap: reserved=4069376KB, committed=920064KB) - Class (reserved=1066121KB, committed=14217KB) (classes #405) (malloc=9353KB #178) (mmap: reserved=1056768KB, committed=4864KB) - Thread (reserved=20646KB, committed=20646KB) (thread #21) (stack: reserved=20560KB, committed=20560KB) (malloc=62KB #110) (arena=23KB #40) - Code (reserved=249655KB, committed=2591KB) (malloc=55KB #346) (mmap: reserved=249600KB, committed=2536KB) - GC (reserved=159063KB, committed=148947KB) (malloc=10383KB #129) (mmap: reserved=148680KB, committed=138564KB) - Compiler (reserved=134KB, committed=134KB) (malloc=3KB #37) (arena=131KB #3) - Internal (reserved=9455KB, committed=9455KB) (malloc=9423KB #1417) (mmap: reserved=32KB, committed=32KB) - Symbol (reserved=1358KB, committed=1358KB) (malloc=902KB #85) (arena=456KB #1) - Native Memory Tracking (reserved=161KB, committed=161KB) (malloc=99KB #1559) (tracking overhead=61KB) - Arena Chunk (reserved=175KB, committed=175KB) (malloc=175KB) A lot more regions than just the heap! Our hello world program just got even more complex... What does all this mean? 1 - Java Heap : heap memory. - Class : is the Metaspace region we previously spoke about. - Thread : is the space taken up by threads on this JVM's. - Code : is the code cache - this is used by the JIT to cache compiled code. - GC : space used by the garbage collector. - Compiler : space used by the JIT when generating code. - Symbols : this is for symbols, by which I believe field names, method signatures fall under. 2 - Native Memory Tracking : memory used by the native memory tracker itself. - Arena Chunk : not entirely sure what this gets used for. 3 Practical memory issues Ok, so why should you care about any of the above? Let's create an app that eats a tonne of memory. // MemEater.java import java.util.Vector; public class MemEater { public static final void main(String[] args) throws Exception { Vector<byte[]> v = new Vector<byte[]>(); for (int i = 0; i < 400; i++) { byte[] b = new byte[1048576]; // allocate 1 MiB v.add(b); } System.out.println(v.size()); Thread.sleep(10000); } } This will create a Vector which contains 400 byte arrays of size 1 MiB 4, so this will use ~400MiB memory on the heap. It will then sleep for 10 seconds so we can get the memory usage easily while it runs. Let's constrain the heap to 450MiB and run this locally we can see the actual memory usage of the process. RSS Resident Set Size 5 is how this is measured, note that this value also contains pages mapped from shared memory, but we can gloss over that for this post. So, lets compile our app, run in the background and get its RSS: $ javac MemEater.java $ nohup java -Xms450M -Xmx450M MemEater & $ ps aux \| awk 'NR==1; /[M]emEater/' USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND chaospie 18019 10.5 3.0 3138368 494448 pts/19 Sl 16:06 0:00 java -Xms450M -Xmx450M MemEater In total, the JVM process needs about 500 MiB to run (RSS is 494448 KiB). What happens if we set the heap to a size lower than it needs? $ java -Xms400M -Xmx400M MemEater Exception in thread "main" java.lang.OutOfMemoryError: Java heap space at MemEater.main(MemEater.java:7) If you have used java (or any JVM language) before, you have more than likely come across this. It means that the JVM ran out of heap space to allocate objects. There are quite a few other types of OutOfMemoryError the JVM can throw in certain situations 6, but I won't go into more detail right now. Now we know what happens if the JVM does not have enough heap space, what about the case where you are running in a container and hit the overall memory limit for that container? The simplest way to reproduce this is to package up our MemEater program into a docker image and run it with less memory than it needs. FROM openjdk:8-jdk ADD MemEater.java . RUN cat MemEater.java RUN javac MemEater.java ENTRYPOINT java -Xms450M -Xmx450M MemEater Again, we need to build the image. However this time when we are running we limit the memory the container is allowed to use to 5M: $ docker build --tag jvm-test . $ docker run -ti --rm --memory 5M --memory-swappiness 0 --name memeater jvm-test WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. Killed After a few seconds you should see the output above, Killed. What happened? Before we dive into that, lets have a look at the --memory and --memory-swappiness flags used by docker. Limiting memory with docker Lets digress for a second, and look at the two docker flags I used above for controlling memory settings 7. First, for these flags to work, your kernel will need to have cgroup support enabled and the following boot parameters set (assuming grub): $ cat /etc/default/grub ... GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1" ... --memory sets an upper bound on the sum of all processes memory usage within a container, the smallest this can go is 4MiB, above we set it to 5m which is 5MiB. When this is set, the containers cgroup memory.limit_in_bytes is set to the value. I can't find the code that does this in docker, however we can see it as follows: $ docker run -d --rm --memory 500M --memory-swappiness 0 --name memeater jvm-test WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. 812dbc3417eacdaf221c2f0c93ceab41f7626dca17f959298a5700358f931897 $ CONTAINER_ID=`docker ps --no-trunc \| awk '{if (NR!=1) print $1}'` $ echo $CONTAINER_ID 812dbc3417eacdaf221c2f0c93ceab41f7626dca17f959298a5700358f931897 $ cat /sys/fs/cgroup/memory/docker/${CONTAINER_ID}/memory.swappiness 0 $ cat /sys/fs/cgroup/memory/docker/${CONTAINER_ID}/memory.limit_in_bytes 524288000 # Again, this time without limits to see the difference $ docker run -d --rm --name memeater jvm-test d3e25423814ee1d79759aa87a83d416d63bdb316a305e390c2b8b98777484822 $ CONTAINER_ID=`docker ps --no-trunc \| awk '{if (NR!=1) print $1}'` $ echo $CONTAINER_ID d3e25423814ee1d79759aa87a83d416d63bdb316a305e390c2b8b98777484822 $ cat /sys/fs/cgroup/memory/docker/${CONTAINER_ID}/memory.swappiness 60 $ cat /sys/fs/cgroup/memory/docker/${CONTAINER_ID}/memory.limit_in_bytes 9223372036854771712 Note the WARNING, I'm not entirely sure why this appears as swap support is enabled, and seems to work. You can ignore this for now. --memory-swappiness sets the swappiness level of the cgroup herarchy the container runs in. This maps directly to the cgroup setting memory.swappiness (at least in version 17.12 of docker 8 ) as seen above. Setting this to 0 disables swap for the container. What kills the container? So, why was the container killed? Lets run it again: $ docker run -ti --rm --memory 5M --memory-swappiness 0 --name memeater jvm-test WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap. Killed To see the cause of this kill, run journalctl -k and search for oom-killer, you should see logs like the following: $ journalctl -k ... Feb 18 17:34:47 kernel: java invoked oom-killer: gfp_mask=0x14000c0(GFP_KERNEL), nodemask=(null), order=0, oom_score_adj=0 Feb 18 17:34:47 kernel: java cpuset=35f18c48d432510c76e76f2e7a962e64a1372de1dc4abd830417263907bea6e0 mems_allowed=0 Feb 18 17:34:47 kernel: CPU: 0 PID: 16432 Comm: java Tainted: G OE 4.13.0-32-generic #35~16.04.1-Ubuntu Feb 18 17:34:47 kernel: Hardware name: Dell Inc. Precision 5520/0R6JFH, BIOS 1.3.3 05/08/2017 Feb 18 17:34:47 kernel: Call Trace: Feb 18 17:34:47 kernel: dump_stack+0x63/0x8b Feb 18 17:34:47 kernel: dump_header+0x97/0x225 Feb 18 17:34:47 kernel: ? mem_cgroup_scan_tasks+0xc4/0xf0 Feb 18 17:34:47 kernel: oom_kill_process+0x219/0x420 Feb 18 17:34:47 kernel: out_of_memory+0x11d/0x4b0 Feb 18 17:34:47 kernel: mem_cgroup_out_of_memory+0x4b/0x80 Feb 18 17:34:47 kernel: mem_cgroup_oom_synchronize+0x325/0x340 Feb 18 17:34:47 kernel: ? get_mem_cgroup_from_mm+0xa0/0xa0 Feb 18 17:34:47 kernel: pagefault_out_of_memory+0x36/0x7b Feb 18 17:34:47 kernel: mm_fault_error+0x8f/0x190 Feb 18 17:34:47 kernel: ? handle_mm_fault+0xcc/0x1c0 Feb 18 17:34:47 kernel: __do_page_fault+0x4c3/0x4f0 Feb 18 17:34:47 kernel: do_page_fault+0x22/0x30 Feb 18 17:34:47 kernel: ? page_fault+0x36/0x60 Feb 18 17:34:47 kernel: page_fault+0x4c/0x60 Feb 18 17:34:47 kernel: RIP: 0033:0x7fdeafb0fe2f Feb 18 17:34:47 kernel: RSP: 002b:00007fdeb0e1db80 EFLAGS: 00010206 Feb 18 17:34:47 kernel: RAX: 000000000001dff0 RBX: 00007fdea802d490 RCX: 00007fdeac17b010 Feb 18 17:34:47 kernel: RDX: 0000000000003bff RSI: 0000000000075368 RDI: 00007fdeac17b010 Feb 18 17:34:47 kernel: RBP: 00007fdeb0e1dc20 R08: 0000000000000000 R09: 0000000000000000 Feb 18 17:34:47 kernel: R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000000000 Feb 18 17:34:47 kernel: R13: 00007fdeb0e1db90 R14: 00007fdeafff851b R15: 0000000000075368 Feb 18 17:34:47 kernel: Task in /docker/35f18c48d432510c76e76f2e7a962e64a1372de1dc4abd830417263907bea6e0 killed as a result of limit of /docker/35f18c48d432510c76e76f2e7a962e64a137 Feb 18 17:34:47 kernel: memory: usage 5120kB, limit 5120kB, failcnt 69 Feb 18 17:34:47 kernel: memory+swap: usage 0kB, limit 9007199254740988kB, failcnt 0 Feb 18 17:34:47 kernel: kmem: usage 1560kB, limit 9007199254740988kB, failcnt 0 Feb 18 17:34:47 kernel: Memory cgroup stats for /docker/35f18c48d432510c76e76f2e7a962e64a1372de1dc4abd830417263907bea6e0: cache:176KB rss:3384KB rss_huge:0KB shmem:144KB mapped_fil Feb 18 17:34:47 kernel: [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name Feb 18 17:34:47 kernel: [16360] 0 16360 1073 178 8 3 0 0 sh Feb 18 17:34:47 kernel: [16426] 0 16426 609544 3160 47 4 0 0 java Feb 18 17:34:47 kernel: Memory cgroup out of memory: Kill process 16426 (java) score 2508 or sacrifice child Feb 18 17:34:47 kernel: Killed process 16426 (java) total-vm:2438176kB, anon-rss:3200kB, file-rss:9440kB, shmem-rss:0kB ... The kernels OOM killer killed the application because it violated it's cgroup memory limit. From the logs above: memory: usage 5120kB, limit 5120kB, failcnt 69 shows it hit the limit, Killed process 16426 (java) total-vm:2438176kB, anon-rss:3200kB, file-rss:9440kB, shmem-rss:0kB shows that it decided to kill process 16426 which was our java process. There is a lot more information in the logs which can help identify the reason why the OOM killer killed your process, however in our case we know why - we violated the container memory limit. With a heap issue, if we hit an out of memory error with Java Heap Space as the cause, we know immediately that the cause is the heap and we are either allocating too much, or we need to increase the heap (actually identifying the underlying cause of this overallocation in the code is another issue...). When the OOM killer kills our process, it's not so straightforward - it could be direct buffers, unconstrained non-heap memory areas (Metaspace, Code cache etc...) or even another process within the container. There is quite a bit to cover when investigating. On that note, I'll finish this post. Conclusion There is quite a lot more that could be said about heap/non-heap memory in the JVM, docker and the oom-killer - but I want to keep this initial post short, it's just meant to be a basic intro to JVM memory usage. Hopefully, if you took anything away from this post, it's that there is much more to think about than just the heap when using the JVM, especially in memory bound containers. See NMT details. ↩ This one I need to look up more in-depth, as I have not been able to find solid information on it. ↩ Arena Chunk seems to be related to malloc arenas, will definitely look into this in-depth. ↩ 1 MiB = 1024 KiB = 1048576 bytes. Why use MiB? Because MB is ambiguous and can mean 1000 KB or 1024 KB, whereas MiB is always 1024 KiB. ↩ See this great answer for a description of RSS. ↩ A detailed description of them can be found here. ↩ The dockerdocumentation on this subject is excellent - see resource constraints. ↩ See docker memory swappiness. ↩ The software industry moves fast. But if you keep up, you can have an incredible career. Join DEV. 100% Free Forever.	https://practicaldev-herokuapp-com.global.ssl.fastly.net/wayofthepie/jvm-basic-memory-overview-535m	CC-MAIN-2020-16	refinedweb	3,116	64.51
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. But this will only cover extension methods that are already pulled into scope, right? It would be helpful to be able to discover extension methods whose namespaces haven't been imported. This would be similar behavior to the rather-useful feature that discovers namespaces for types and offers to import or prepend them. "It would be helpful to be able to discover extension methods whose namespaces haven't been imported." That would clutter up intellisense. I don't want to be bothered with details about a namespace i didn't import. If you are interested in the future of VB, or .NET in general because this is equally true for C#, you I was just reading Rocky's blog entry and thought I'd clarify something Rocky said : Running a LINQ query Nice to hear from you again Scott!! Nate In my previous post I gave a high level overview of some of the benefits of using Extension Methods in kfarmer, Thanks for the feature idea. I can't guarantee that we will be able to include your feature in Orcas, but I will forward your request over to the UI team for consieration in a future version of the product. One things to consider is that although extension methods are only visible if they are in scope, if you define an extension method in a module in the top level namespace of your of your project (or solution), then you can use these extension methods without having to explictly import them in every file in your project. This won't help with discoverability of extension methods written by third party class library authors, but it will help with extension methods that you or other people on your projects write. -Scott Will it be ever possible to replace not-virtual private and protected methods/properties in compiled assemblies? Thanks. In my previous 2 posts I talked about some of the benefits of extension methods and then delved into Hex, Thank you for your suggestion. At the momenet we have no plans to support allowing extension methods to override eixsting instance methods. In fact the feature is specifically designed to not allow extension methods to replace the definition of instance methods (instance methods hide extension methods by name, so an extension mehtod can never be called if an instance method with the same name exists on the class). Hower, I will forward your suggestion over to our langauge design team so that they can consider it for a future version of the product. Thanks, Here is a list of links to posts on this blog that talk about extension methods: Extension Methods Part L'avvento di .NET 3.5 porterà ai linguaggi che usiamo di più (C# e VB) una serie di novità che sono principalmente	http://blogs.msdn.com/b/vbteam/archive/2007/01/05/extension-methods-part-1.aspx?Redirected=true	CC-MAIN-2015-22	refinedweb	465	55.78
On Friday, 27 July 2012 at 19:01:39 UTC, Namespace wrote: > I also get null references (and every time I hate D a bit > more), but mostly my classmates and other friends whom I've > shown D. And most of them are already back to C++ or C#. And I > can understand them. > If you want that D is sometimes taken seriously (and it reached > only if you win more people for D), then perhaps you should do > something for more usability. > Such small handy shorthands are easy to implement and even more > understandable as a stacktrace. I've noticed when debugging the 'segfault' is rather vague, but it depends on if you have something to catch it. In some of my code I end up surrounding the main function in a try/catch wrapper that prints the appropriate data; Like using VisualD. void main() { try { someFunc(null); } catch (Throwable x) { writeln(x); } } void someInnerFunc(Object o) in { assert(o, "Yo! my object's NULL!"); } body { //something } void someFunc(Object o) { someInnerFunc(o); //for stacktrace } core.exception.AssertError@test.d(111): Yo! my object's NULL! ---------------- c:\Users\Era\My Documents\progs\d\test.d(119): void test.someFunc(Object) c:\Users\Era\My Documents\progs\d\test.d(103): _Dmain change inner function to: void someInnerFunc(Object o) { o.toHash; //something } object.Error: Access Violation ---------------- c:\Users\Era\My Documents\progs\d\test.d(116): void test.someFunc(Object) c:\Users\Era\My Documents\progs\d\test.d(103): _Dmain On Windows, an access violation (from a null pointer or other causes) is an exception that is thrown and can even be caught. On Linux, a segfault is a signal that just kills the program, it doesn't work like a regular exception. The Windows exceptions can do pretty stack traces, including on null derefs, if you have some debugging library installed... and I've done it before, but I don't remember the link right now. It's something from Microsoft. On Friday, 27 July 2012 at 19:48:33 UTC,. Linux also dumps the state into a file. So I'd have to wonder what the problem was, you would have all the information at hand. On Friday, 27 July 2012 at 19:50:46 UTC, Era Scarecrow wrote: > Linux also dumps the state into a file. Only if core dumps are enabled... but I think someone did a Linux stack trace signal handler somewhere for D, but it never got merged into druntime. (What it'd do is print out some info before exiting, instead of just saying "segmentation fault". Still not an exception, but a little more immediately helpful). And that is the explicit way with pre- and postconditions of Java, which i want to avoid. I see, the most of you prefer to write "try and catch" or use the java principle with explicit pre- and post conditions. The time will show, if D get therewith enough members to get serious. But this is what Java and C# have already. On 07/27/12 21:48,. It's not a regular D exception, but it is a signal that /can/ be caught and used to print stacktraces, file names, line numbers etc, not to mention you optionally get a snapshot of the program as it failed (the "core" file). The only non-trivial part is getting at the debug info to map the addresses to symbols. Simple quick and dirty example below, which will not only print the address of the instruction that caused the fault, but also the address that it tried to access, and may even sometimes succeed in letting the program continue to run. Making it work with a non-gdc compiler, non-x86 ISA, hooking up w/ a library to get all the symbol names and properly handling all the required cases is left as an exercise for the reader. :) But, no, special handling for null dereferencing in the language is not needed. Some more runtime support, maybe. artur import std.stdio; template Seq(alias A, alias B, S...) { static if(S.length==0) alias Seq!(A, B, A) Seq; else static if (S[$-1]!=B) alias Seq!(A, B, S, S[$-1]+1) Seq; else alias S Seq; } struct hack { import core.sys.posix.ucontext, core.sys.posix.signal; alias int c_int; static: void* av; ubyte* violator; void[4] trace; extern (C) void handler(c_int signum, siginfo_t si, void* _ctx ) { auto ctx = cast(ucontext_t)_ctx; av = si._sifields._sigfault.si_addr; version (X86) enum REG_RIP = 14; violator = cast(ubyte)ctx.uc_mcontext.gregs[REG_RIP]; ctx.uc_mcontext.gregs[REG_RIP] += inslen(violator); // scan and store backtrace etc. version (GNU) { import gcc.builtins; foreach (uint i; Seq!(0, trace.length-1)) trace[i] = __builtin_return_address(i); } checkav(); // Not something you wanna do from a signal handler... } void register() { sigaction_t sa; sa.sa_sigaction = &handler; sa.sa_flags = SA_SIGINFO; if (sigaction(SIGSEGV, &sa, null)) throw new Error("sigaction failed"); } version (X86) size_t inslen(in ubyte* c) { if (c[0]==0xc6 && c[1]==0x05) return 7; if (c[0]==0x0f && c[1]==0xb6 && c[2]==0x4b) return 4; if (c[0]==0x0f && c[1]==0xb6 && c[2]==0x43) return 4; if (c[0]==0x0f && c[1]==0xb6) return 7; if (c[0]==0xa2) return 5; if (c[0]==0x65 && c[1]==0xc7) return 11; if (c[0]==0x88 && c[1]==0x4b) return 3; // ... return 1; } auto checkav() { if (av) { writefln(" 0x%08x tried to access 0x%08x", violator, av); foreach(t; trace) writef(" 0x%08x\n", t); av = null; } } } __gshared ubyte* p = null; int main() { hack.register(); p[1] = 1; hack.checkav(); p[2] = 2; hack.checkav(); p[3] = 3; hack.checkav(); p[5] = p[4]; hack.checkav(); return p[42]; } Me again. What's the matter if i write something for that shorthand and dmd has only to switch to it before the compiling begins? My little test program works with VisualD. I goto the build events and there i write into "Pre-Build Command": [quote]not_null main.d #t[/quote] and into "Post-Build Command": [quote]del main.d rename clone_main.d main.d[/quote] Of course i have to find a way to generate this for all included files and not do this manually as not_null a.d #t not_null b.d #t But if dmd would do this e.g. with a compiler flag like "-notnull" it would lighten my workload a lot. Here is my current example code: It replace Class? obj statements and generate two files. The normal file changes to valid D code which can compile. The "original" code with Class? obj statements will copied into clone_filename.d I know it isn't perfect, but maybe it is a beginning. On Saturday, July 28, 2012 01:00:22 Namespace wrote: > Me again. > What's the matter if i write something for that shorthand and dmd > has only to switch to it before the compiling begins? Doing stuff like that makes your code completely unportable. It's _bad_ practice. Don't go and try to redesign the language if you want to be playing nice with other people. If you can do something completely within the language, then that's different (other people may still hate what you're up to, but at least they can compile it), but don't use a preprocessor unless you really don't care about anyone else ever using your code but you, and even then, I'd argue against it, because if you get into the habit of doing that, you're screwed when you actually have to interact with other D programmers. - Jonathan M Davis Therefore i hope that it will be official added into D. Otherwise of course i use it only for projects between me and my other students. I don't know what is wrong with this shorthand. So why don't give it a try? I'm absolutely sure that Walter will _never_ add real non-nullable references. All what will maybe come are further structs in std.alghorithm which blows up your code as assertions even do. I started a not null struct for phobos but then had to move, added another job, and other real life stuff that meant I haven't finished it yet. Fairly usable though. Look for struct NotNull: (also a pull request, but for some reason, my changes to never updated here, so the pull request is out of date and temporarily closed )	http://forum.dlang.org/thread/gajrorlwnrriljxnxfmt@forum.dlang.org?page=3	CC-MAIN-2015-06	refinedweb	1,409	66.84
tag:blogger.com,1999:blog-76243946861487119902009-07-06T07:05:03.109+10:00dave^2 = -1A software development blog by some bloke called Dave.David Live Template for Dependency Properties (C#)<p>The syntax for declaring WPF dependency properties can get a little tedious to type. I ended up creating a ReSharper Live Template which has been working nicely for me:</p> <pre class="brush:csharp"> public static readonly DependencyProperty $PropertyName$Property = DependencyProperty.Register("$PropertyName$", typeof($PropertyType$), typeof($PropertyOwner$)); public $PropertyType$ $PropertyName$ { get { return ($PropertyType$) GetValue($PropertyName$Property); } set { SetValue($PropertyName$Property, value); } } </pre> <p>Then configure the substitutable variables as follows:</p> <ul> <li>PropertyName, no macro, #3 editable</li> <li>PropertyType, Guess type expected at this point, #2 editable</li> <li>PropertyOwner, Containing type name, not editable</li> </ul> <p>This lets me type in <code>dp</code> and fill in the blanks. trouble mocking generic methods<p>I've seen a few people get bitten by an edge case of using generics with mocking frameworks. Let's look at a contrived example and see what's going on. We're using Rhino Mocks 3.5 in this case, but the symptoms described here are not specific to that mocking framework, but rather are related to how generics work in .NET.</p> <pre class="brush:csharp"> public interface IFish{} public class Eric : IFish{} public interface IAquarium { IEnumerable<T> FindEverythingLike<T>(T thisThing); } [Test] public void LookingForALicenceForMyPetFishEric() { var petFish = new Eric(); var expectedErics = new[] {petFish}; IAquarium stubAquarium = MockRepository.GenerateStub<IAquarium>(); stubAquarium .Stub(aquarium => aquarium.FindEverythingLike(Arg<IFish>.Is.Anything)) .Return(expectedErics); var actualErics = stubAquarium.FindEverythingLike(petFish); Assert.That(actualErics, Is.EqualTo(expectedErics)); } </pre> <p>Here we're asking our stubbed <code>IAquarium</code> to return an <code>expectedErics</code> array whenever it gets any <code>IFish</code> as an argument to the generic <code>FindEverythingLike<T>()</code> method. We then pass our <code>petFish</code> to the method and get the actual enumerable returned from our stub. So what does this assertion give us?</p> <pre> MockingGenerics.LookingForALicenceForMyPetFishEric : FailedNUnit.Framework.AssertionException: Expected: < <Workshop.Tests.Eric> > But was: null </pre> <p>Oops, our stubbed value hasn't been returned. Our <code>petFish</code> is an instance of class <code>Eric</code>, which implements <code>IFish</code>, so why isn't our stub returning our <code>expectedErics</code>?</p> <p>The reason for this is that we are actually stubbing out <code>FindEverythingLike<IFish>()</code>, but are calling <code>FindEverythingLike<Eric>()</code>. While we declare this as a single generic method, the CLR actually calls these as two completely different method instances. This is obscured a bit by the fact that type inference is used to determine which method instance is called. If we don't rely on type inference we can get the test to pass:</p> <pre class="brush:csharp"> var actualErics = stubAquarium.FindEverythingLike<IFish>(petFish); Assert.That(actualErics, Is.EqualTo(expectedErics)); </pre> <p>In the real examples where I've seen errors like this we generally have more collaborators involved and the problem becomes harder to detect. It's not a common case, requiring us passing different static types to a generic method where at first glance it looks reasonable to expect our call to resolve to the one method.</p> <p>Just to belabour the point for one more example, let's just confirm that it is the static type of our reference that determines which method instance is called, rather than the actual instance type:</p> <pre class="brush:csharp"> [Test] public void GenericsAndMockingCanBeTroublesome() { IAquarium mockAquarium = MockRepository.GenerateMock<IAquarium>(); Eric petFish = new Eric(); IFish sameFish = petFish; mockAquarium.FindEverythingLike(petFish); mockAquarium.AssertWasCalled(aquarium => aquarium.FindEverythingLike(sameFish)); } </pre> <p>This case fails, as we are calling <code>mockAquarium.FindEverythingLike<Eric>()</code>, but asserting that <code>FindEverythingLike<IFish>()</code> was called. Even though it is the same instance, the declared types of each reference at compile time are the ones that are used to dispatch to our generic method instance.</p> <p>Hope this helps save someone a couple of minutes of frustration. :)< unit testing post in PDF format<p>My last post on <a href="">Moving to scenario-based unit testing in .NET</a> was pretty long, even for me. I've just gone and done a rough conversion of it to PDF, so if you felt the topic was vaguely interesting but were put off by having to scroll through loads of my aesthetically-challenged blog screens, then feel free to give the PDF a go. I feel it would have really helped me had I read it a year or so ago, so I thought I'd put it in a more readable format to try and encourage someone else to actually read it. :)</p> <p to scenario-based unit testing in .NET<div class="note"><p>This post is pretty long, even for me. You can download it as a <a href="">PDF file</a> (roughly converted) which might be a bit easier to read.> <p>From my observations most developers (myself included) start writing tests using <a href="">one testcase class per class under test</a>. Due to an unfortunate attribute naming choice, NUnit users may know this as "fixture per class", and implement it as one class marked <code>[TestFixture]</code> holding all the tests that relate to one production class.</p> <p Life<sup>TM</sup> ends in pain, frustration, nausea, alcoholism and, in rare cases, spontaneous human combustion. Even worse, it may cause developers to abandon writing unit tests altogether!</p> <p>There are many alternatives for organising tests (testcase class per fixture, feature, method, etc.), but the one I've found easiest to adopt and use is a testcase class per <i>scenario</i>..</p> <p>The aim of this post is to describe what on earth I'm talking about, as well as how to move from testcase class per class to scenario-based testcase classes, and also outline some of the unresolved problems we've run into with this approach.</p> <h2>A note on terminology</h2> <p>I'm probably drastically misusing terminology here when I talk about scenario-based testing. The way I'm using the term "scenario" seems quite different to <a href="">scenario-based testing</a> as described in Wikipedia, but I don't know a better name for it. The word "scenario" is used a lot when talking about <a href="">Behaviour Driven Development (BDD)</a>! :)</p> <h2>The example</h2> <p:</p> <ul> <li>The screen should display a welcome message to the agent using the Doomsday Device.</li> <li>The user can click a button to fire the Doomsday Device</li> <li>After firing, the user cannot click the button again until the Doomsday Device has finished its firing sequence</li> </ul> <p!".</p> <h2>Testcase class per class</h2> <p>We start off by creating a <code>DoomsDayDevicePresenterFixture</code>, and then begin writing tests and filling in passing implementations. Here is what our fixture looks like when we're done:</p> <pre class="brush:csharp"> /); } } </pre> <p>Our tests all pass. Hooray!</p> <h2>What's wrong with this?</h2> ).</p> <p>The main source of the cohesion problem is the setup used for each test. The testcase class has its own setup method, but the first few lines of each test performs some additional setup. In somes cases, such as the <code>ShouldDisableFireButtonWhileFiring()</code> and <code>FireButtonShouldFireDoomsDayDevice()</code>,.</p> <p.</p> <p.</p> <h2>Testcase class per fixture?</h2> <p>The setup required for a series of tests is generally called the <i>test fixture</i> --.</p> <p>All the tests start with a call to <code>RaiseLoadedEventOnView()</code>, so we could just whack that in the setup and have a fixture for all our tests the rely on the loaded view. Except for the <code>ShouldWelcomeEvilAgentWhenLoaded()</code>,.</p> <p.</p> <p <a href="">people</a> <a href="">much</a> <a href="">smarter</a> than me (although less bloggish :)) got together and came up with a better solution that everything started to click into place.</p> <h2>Testcase class per scenario</h2> <p.</p> .</p> <p.</p> <h2>Refactoring toward scenario-based tests</h2> <p <i>when the view is loaded</i> (<code>ShouldWelcomeEvilAgentWhenLoaded()</code> and <code>ShouldEnableFireButtonWhenViewLoaded()</code>). We also have <code>ShouldDisableFireButtonWhileFiring()</code>. When is the device firing? Looking at the code in that test, it is <i>when the fire button is pressed</i>. The <code>FireButtonShouldFireDoomsDayDevice()</code> also seems to relate to this scenario. And lastly we have <code>ShouldEnableFireButtonWhenFiringCompleted()</code> -- so <i>when firing completed</i> sounds like a good scenario for that one. (You don't have to identify all the scenarios up front, just enough to get you started.)</p> <p.</p> <p.</p> <p>Let's have a look at the <i>when view is loaded</i> scenario. I'll create a new subfolder in our test project called <code>DoomsDayDevicePresenterScenarios</code>, then create a <code>WhenViewLoaded.cs</code> class. I'm quite a fan of underscore-overload (cue <a href="">shameless post plug</a>), so I'd prefer to use <code>When_view_loaded</code>, but I'll try and skip potentially heated debates for now. :)</p> <p>The code below is how it looks after refactoring out some duplication:</p> <pre class="brush:csharp">); } } } } </pre> <p.</p> <div class="note">You may have noticed a weird partial class thingoe happening here. This was suggested by a <a href="">colleague</a> to make scenarios more discoverable from within Resharper. If all scenarios related to our presenter are inner classes of the <code>DoomsDayDevicePresenterScenario</code> partial class, then Resharper's "go to type" command (<code>Ctrl + T</code> on my configuration) will let us select the partial class, then list all the scenarios for us to jump to. It adds some code noise, and isn't strictly necessary, but does make navigating around your tests easier.</div> <p>Let's move on to our next scenario.</p> <pre class="brush:csharp">); } } } </pre> <p>Compare this to how one of these tests used to look.</p> <pre class="brush:csharp"> / plus [SetUp] method code / [Test] public void FireButtonShouldFireDoomsDayDevice() { RaiseLoadedEventOnView(); RaiseFireButtonPressedOnView(); stubDoomsDayDevice.AssertWasCalled(device => device.Fire()); } </pre> <p.</p> <p>Let's look at the final scenario, and at our base class which we have used to keep duplication in check (although not eliminated, as we'll discuss later).</p> <pre class="brush:csharp"> ); } } </pre> <pre class="brush:csharp">); } } </pre> <h2>Issues with this approach</h2> <h3>Duplication in setup methods</h3> <p>All the <code>[SetUp]</code> <a href="">Reuse: Friend or Foe</a> in an article on BDD for CoDe Magazine:</p> <blockquote> " </blockquote> <p).</p> <p <a href="">JP Boodhoo's developwithpassion.bdd approach</a>, which has the downside of looking completely foreign to people who speak C#, but has the upside of being really nice once you get used to it.</p> <p>If the duplication bothers you, you can have a general context base class with an existing <code>[SetUp]</code> method that provides hooks like <code>BeforeSetup()</code>, <code>AfterDependenciesCreated()</code> etc. This lets your scenarios hook into whichever parts of the setup chain it needs to and do things like stub out calls. The real trick comes when you want to chain together contexts, which is something <a href="">JP's</a> approach gives you, and something which you get for free with tools like rspec (using <a href="">nested blocks</a>).</p> <p.</p> <h3>What goes into the base class?</h3> <p.</p> <h3>Tests that apply to multiple scenarios</h3> <p <code>Always</code>, or if you like the when-convention, <code>WhenEver</code> :).</p> <p.</p> <p>We've used all three approaches, with my preference being for isolating the behaviour properly. The <code>WhenEver</code> style approach feels a bit dirty but hasn't caused much grief. The inherited test thing has had mixed results.</p> <h3>Using in conjunction with other organisational methods</h3> <p.</p> <h2>Conclusion</h2> <p.</p> <p disappointment<p>I've been eagerly awaiting .NET 4 and the new <code>dynamic</code> feature in C#, but after taking the beta for a spin I've run in to a major disappointment. Let's take <code>dynamic</code> for a quick spin and see what's got me so devastated.</p> <pre class="brush:csharp">)); } } </pre> <p>Here we've created a sub-class of <code>DynamicObject</code>, which lets us play in the world of dynamic lookups from C#. We override <code>TrySetMember(...)</code> and <code>TryGetMember(...)</code> to use a dictionary as a backing store for members. Our test assigns a method called <code>AMethod</code> to a dynamic object at run time, then executes it. It passes! Awesome!</p> <h2>If it walks and quacks like a duck, too bad!</h2> <p>Let's declare an <code>ICanAdd</code> interface, as well as a class that uses objects that support the <code>ICanAdd</code> interface to, well, add stuff.</p> <pre class="brush:csharp">); } } </pre> <p>We can add this method to our dynamic object so that it supports the same operations as the <code>ICanAdd</code> interface:</p> <pre class="brush:csharp"> [Test] public void CanCreateADynamicAdder() { dynamic adder = new Dynamic(); adder.Add = new Func<int, int, int>((first, second) => first + second); Assert.That(adder.Add(1, 3), Is.EqualTo(4)); } </pre> <p>This works fine, but when we try to combine static and dynamic worlds we run into problems:</p> <pre class="brush:csharp"> )); } </pre> <p>This compiles, but at runtime we get the test failing with the following <code>RuntimeBinderException</code>:</p> <pre>() ... </pre> <p>The exception is fairly clear -- the C# <code>RuntimeBinder</code> is trying to call the <code>SomethingThatAdds(ICanAdd)</code> constructor, but we've given it a <code>dynamic</code> instance instead. Based on my fairly primitive understanding of this stuff, in order to integrate dynamic lookups into the statically typed CLR, <code>dynamic</code> is actually implemented as a static type. So even though we're using dynamic member lookups at runtime, we still need to abide by the type system and pass methods the static types they expect.</p> <p>If we modify our original <code>SomethingThatAdds</code> class to explicitly accept the <code>dynamic</code> type then our last test passes:</p> <pre class="brush:csharp"> public class SomethingThatAdds { private dynamic adder; public SomethingThatAdds(dynamic adder) { this.adder = adder; } / ... snip ... / } </pre> <p>I'm aware I'm probably expecting too much, but having to explicitly modify our code in order to make this kind of use of the dynamic feature for <a href="">duck typing</a> is, well, disappointing. It would be great to see something like <a href="">Jon Skeet's <code>dynamic<T></code> idea</a> get into the final release so we can get the best of both worlds. :)< up Git difftool on Windows<p>After installing Windows 7 I had trouble getting <a href=""><code>git diff</code> to work properly with diffmerge</a>. In fact, any external tool I tried to define would hang PowerShell once it exited. Unfortunately in the time I had to look at it I couldn't figure out if this was due to a new version of PowerShell with Windows 7, the new version of <a href="">MSys Git</a> I had installed, or something strange after switching to x64 architecture. What I did have time for was to find a workaround using <code>git difftool</code>, which is a new command added to Git as of version 1.6.3.</p> <p>The workaround is essential just a tweak of <a href="">the steps we used previously to get <code>git diff</code> working</a>, so its probably easiest to have a quick skim through that before going through this.</p> <h2>Configuration tweaks</h2> <p>First alteration to the previous approach was to create a difftool wrapper for Diffmerge. I called this <code>git-diff-diffmerge-wrapper.sh</code> and put it in my <code>Git/cmd</code> directory (which is also on my PATH).</p> <pre> #!/bin/sh "C:/Program Files (x86)/SourceGear/DiffMerge/DiffMerge.exe" "$1" "$2" \| cat </pre> <p>Next step was to update <code>.gitconfig</code> to disable the previously added external tool setup for <code>git diff</code>, and configure <code>git difftool</code> in its place.</p> <pre> [diff] #external = git-diff-wrapper.sh tool = diffmerge [difftool "diffmerge"] cmd = git-diff-diffmerge-wrapper.sh "$LOCAL" "$REMOTE" # ... snipping rest of .gitconfig ... # </pre> <p>I've left the external tool commented out (prefixed by #). This syntax is more in line with the way the we configured the <code>git mergetool</code> <a href="">last time</a>.</p> <h2>Using <code>git difftool</code></h2> <p>Now whenever we type <code>git diff</code> we will get the standard, textual git difference listing. If we want to use the externally configured tool, we need to type <code>git difftool</code> (followed by the usual range of <a href="">diff options</a>) (<code>git mergetool</code>).</p> <p>I wish I knew what caused my original issue, but at least I've got my graphical diff tools back for Git. :)< .NET builds using Rake<p>I was starting up a new hobby project the other night and thought I'd try using <a href="">Rake</a> to script my build (instead of pure MSBuild, Nant, or just plain VS). Now Ruby and I generally don't get on too well, so I was really surprised with how easy I found it to setup, and even more surprised with how much I enjoyed it. :)</p> <h2>Prerequisites</h2> <p>Um, <a href="">Ruby</a>. The installer I used gave me Ruby with Rake included. We'll also need a simple .NET solution. I created one with a structure that looked a bit like this:</p> <ul> <li class="folder-icon">DaveSquared.SampleProject</li> <ul> <li class="folder-icon">build</li> <ul><li class="file-icon"><b>rakefile.rb</b></li></ul> <li class="folder-icon">src</li> <ul> <li class="folder-icon">DaveSquared.SampleProject.Tests</li> <li class="folder-icon">DaveSquared.SampleProject.Web</li> <li class="file-icon">DaveSquared.SampleProject.sln</li> </ul> <li class="folder-icon">tools</li> <ul> <li class="folder-icon">NUnit</li> </ul> </ul> </ul> <p>The SLN file contains two projects, <code>DaveSquared.SampleProject.Tests</code> and <code>.Web</code>. The <code>.Tests</code> project references the <code>.Web</code> project, as well as the NUnit framework buried somewhere in the <code>tools/NUnit</code> directory. Both projects where configured to build to the <code>build/output</code> directory (so <code>.Tests</code> will build to <code>build/output/DaveSquared.SampleProject.Tests</code>).</p> <p>We can now setup our <code>rakefile.rb</code>, which I've plonked into the <code>build</code> directory. We'll run the build from this directory, so we can specify all our paths relative to this build file.</p> <h2>Basic build and test run</h2> <p>After reading Dave Laribee's post on <a href="">OMG Rake!</a>, and Mark Guzman's excellent post on <a href="">Building .NET projects with rake</a>, I then proceeded to ruin all their good work by patching bits and pieces of their posts together and got this:</p> <pre> require 'rake/clean' DOT_NET_PATH = "#{ENV["SystemRoot"]}\\Microsoft.NET\\Framework\\v3.5" NUNIT_EXE = "../tools/Nunit/bin/nunit-console.exe" SOURCE_PATH = "../src" OUTPUT_PATH = "output" CONFIG = "Debug" <b>CLEAN.include(OUTPUT_PATH)</b> <b>task :default => ["clean", "build:all"]</b> namespace :build do <b>task :all => [:compile, :test]</b> desc "Build solutions using MSBuild" <b>task :compile do</b> solutions = FileList["#{SOURCE_PATH}//.sln"] solutions.each do \|solution\| sh "#{DOT_NET_PATH}/msbuild.exe /p:Configuration=#{CONFIG} #{solution}" end end desc "Runs tests with NUnit" <b>task :test => [:compile] do</b> tests = FileList["#{OUTPUT_PATH}/*/.Tests.dll"].exclude(/obj\//) sh "#{NUNIT_EXE} #{tests} /nologo /xml=#{OUTPUT_PATH}/TestResults.xml" end end </pre> <p>Now the good thing about this is that I don't think you need to know much (any? I know virtually none) Ruby to understand what is going on here, or even to make basic modifications to the tasks (although it might be a struggle if you haven't used build tools like <code>make</code> or </code>nant</code> before). But you can bring the full power of the language to bear when you need it. Let's have a quick step through the main parts of the file.</p> <p>The first line imports <code>rake/clean</code>, which lets us use <code>CLEAN.include(OUTPUT_PATH)</code> to tidy up for us. We've then got loads of constants to specify various paths: the location of .NET tools like <code>msbuild</code>, and the relative paths to NUnit, our source, and our output. Our <code>:default</code> task is set to run <code>clean</code>, then <code>build:all</code> (the => syntax translates to <i>depends on</i> in <code>make</code> terms, so to run the default task rake will make sure its dependencies are run).</p> <p>If we drop into the <code>:build</code> namespace, we have <code>:all</code>, <code>:compile</code> and <code>:test</code> tasks defined. To <code>:compile</code>, we use the wonderful <code>FileList</code> class built into rake to get all <code>.sln</code> files in our source directory, then shell out to <code>msbuild</code> to take care of the hardwork of compiling everything. The <code>:test</code> task relies on convention, by finding all <code>.Tests.dll</code> files and running them through NUnit. We also make sure that <code>:test</code> won't run until <code>:compile</code> has run by setting <code>:compile</code> as a dependency.</p> <p>Finally, our <code>:all</code> task compiles and tests the build.</p> <h2>Running our rake build</h2> <p>By dropping into our build directory from the command line, just typing <code>rake</code> will pickup our <code>rakefile.rb</code> and execute our default task, which will clean, compile and test our build. We can also run a task at a time, say <code>rake clean</code>, or <code>rake build:test</code> (the <code>:test</code> task is prefixed by <code>build</code> because of its namespace).</p> <p>There's obviously tonnes we could do to make this nicer (like using <a href="">Mark's .NET tasks</a>, and/or removing the hard-coded Debug configuration), but hopefully this gives people a quick way to start getting into rake and ruby for building .NET projects.< test what you are trying to test<p>Had a problem today that initially took me by surprise. The problem was that this test passed:</p> <pre> [Test] public void EmptyBlocksShouldBeEqual() { var first = new Block(); var second = new Block(); Assert.That(first, Is.EqualTo(second)); } </pre> <p>Why was this a problem? Because <code>Block</code> is a reference type and I had not overridden <code>Equals(Object o)</code>, so we should fall back to the default <code>Object.Equals(Object o)</code> method which compares object references. The references are clearly different, so this test should fail.</p> <p>To figure out why this test passes we need two pieces of information. First we need to know how <code>Block</code> is defined:</p> <pre> public class Block : IEnumerable<FrameParameters> { /* ... snip ... / } </pre> <p>Second, we need to know that the NUnit <code>EqualConstraint</code> implementation has specific handling for <code>IEnumerable</code> classes. So when I called <code>Assert.That(first, Is.EqualTo(second));</code>, this was just comparing the values returned via enumerating both <code>Block</code> instances. This really wasn't what I wanted -- I was trying to test the <code>Equals()</code> implementation. Here's the corrected test:</p> <pre> [Test] public void EmptyBlocksShouldBeEqual() { var first = new Block(); var second = new Block(); Assert.That(<b>first.Equals(second)</b>); } </pre> <p>The moral of the story: make sure you explicitly test what you are trying to test. :)< LINQy?<p>This post contains a tale of two methods. Well, more precisely, a tale of one method implemented in two different ways -- once using LINQ-based functional-fu, and once using old school procedural code.</p> <p>Recently I was pairing on a task that required us to keep a running average of multiple sets of samples that came through our app. Unfortunately it was more than likely that some sets of samples would be different lengths (depending on exactly when sampling stopped). In these situations where we were missing samples the requirements were to leave the averages for the missing samples unchanged. When we had extra samples, we should use them as the new average at that position. Here's some tests that hopefully show what we were trying to do:</p> <pre> [Test] public void ShouldAverageFirstTwoLotsOfSamples() { var firstSamples = new float[] { 1, 2, 3 }; var secondSamples = new float[] { 3, 4, 5 }; var expectedAverages = new float[] {2, 3, 4}; _averager.AddSamples(firstSamples); _averager.AddSamples(secondSamples); Assert.That(_averager.GetAverages(), Is.EqualTo(expectedAverages)); } [Test] public void ShouldAddExtraSamplesToAverages() { var firstSamples = new float[] { 1, 2, 3 }; var secondSamples = new float[] { 3, 4, 5, 2 }; var expectedAverages = new float[] { 2, 3, 4, 2 }; / ... snip ... / } [Test] public void ShouldHandleShorterNumberOfSamples() { var firstSamples = new float[] { 1, 2, 3 }; var secondSamples = new float[] { 3, 4 }; var expectedAverages = new float[] { 2, 3, 3}; / ... snip ... / } </pre> <h2>A LINQ implementation</h2> <p>After a brief flurry of <code>for</code> looping, we decided to muck around with LINQ to filter and transform the sets of data in a pseudo-functional kind of way.</p> <pre> public class AverageCalculator { private float[] _averages = new float[0]; private uint _numberOfAverages; public void AddSamples(float[] samples) { _numberOfAverages++; var numberOfNewSamples = samples.Length; var numberOfSamplesInLastAverage = _averages.Length; var leftOverSamples = samples.Skip(numberOfSamplesInLastAverage); var leftOverAverages = _averages.Skip(numberOfNewSamples); <b>_averages = _averages .Take(numberOfNewSamples) .Select( (average, sampleIndex) => CalculateNewAverage(average, samples[sampleIndex], _numberOfAverages) ) .Concat(leftOverAverages) .Concat(leftOverSamples) .ToArray();</b> } private float CalculateNewAverage(float oldAverage, float newSample, uint totalSamples) { return oldAverage + (newSample - oldAverage) / totalSamples; } public float[] GetAverages() { return _averages; } } </pre> <p>Stepping through the logic, we take a maximum of <code>numberOfNewSamples</code> from the running <code>_averages</code>, then calculate the new averages based on each new sample. To handle the possibility of mismatched array sizes, we concatenate any left over items from each array. In reality, one of these arrays of left overs will be empty (depending on which array is larger).</p> <p>My first thought once the tests went green was "wow that's evil!", but compared with the procedural approach we started with, this one really began to grow on me. It was surprisingly easy to write, but I was concerned about its readability (initially we had the local variables in <code>AddSamples(...)</code> inlined, but we extracted them out to try and make it more readable). We decided to test out the procedural equivalent and see if that was any clearer.</p> <h2>A procedural implementation</h2> <pre> public void AddSamples(float[] samples) { _numberOfAverages++; var largestArray = (samples.Length >= _averages.Length) ? samples : _averages; var smallestArray = (samples.Length >= _averages.Length) ? _averages : samples; var newAverages = new float[largestArray.Length]; for (int i = 0; i < newAverages.Length; i++) { newAverages[i] = (i < smallestArray.Length) ? CalculateNewAverage(_averages[i], samples[i], _numberOfAverages) : largestArray[i]; } _averages = newAverages; } </pre> <p>The logic used here is to find which array is largest, and to create a new array of that size. We loop through every possible index, calculating the average until all of the smallest array is used, then append the left overs from the largest array. This seems quite neat to me, although I should mention that this is a refactored, sanitised version (as is the LINQ version). The initial implementation was more verbose and the logic less clear, and it somehow managed to take longer to get it to a state where the tests all passed.</p> <h2>Who's right?</h2> <p>Which approach do you like best? It probably comes down to how much <a href="">imperative</a> vs. <a href="">functional</a> programming you've done. (Or you hate both versions of the method, in which case please leave a comment with the correct approach. :)). Imperative programming concentrates on telling the computer <i>how</i> to do something, while functional is more about telling the computer <i>what</i> to do. For example, our LINQ version starts with some data and specifies what transformations we want to make to it. Our second version of the code focuses more on the mechanics -- create an array, loop, check the bounds etc.</p> <p>The second version's focus on implementation makes it fairly easy to mentally trace through how it works, but how clear is the intention behind the implementation? The LINQ version probably takes a bit more effort to understand how it works (especially as the first exposure most people have to programming tends to be to imperative-style control structures like <code>IF</code>, <code>FOR</code>, <code>WHILE</code> and even <CODE>GOTO</CODE>), but what it is doing might be a little clearer.</p> <p>Overall, I kind of prefer the LINQ version for its faint hint of functional elegance, but on the other hand the procedural version is just so darn familiar and comfortable to read for a C#/Java/C person like me. I'd love to hear any thoughts you have on these approaches, and how you are handling the encroachment of functional concepts into our formerly purely-procedural C# language.< Race Pt 3: It's GUI time!<p><i>This post is <a href="">part of a series</a> exploring the (very) basics of iterative development using the example of a simple <a href="">Snakes and Ladders</a>-like game. Links to each post in the series will be added to the <a href="">index page</a>.</i></p> <p>After having a think about <a href="">top-down and bottom-up design</a>, I concluded that delivering complete vertical slices was more important than whether you started at the top or bottom of the slice. As most of the work in previous iterations has been closer to the bottom of our design, it now seems a good time to start writing some tests around the GUI. This work will form the basis of this iteration.</p> <div class="note"><b><i>Confession</i></b>: I had about 3 attempts at this installment of the series over the last year or so, each time having something crop up that stopped me working on it. Some of this post may be biased by previous attempts, although with my poor memory there shouldn't be too much chance of that. :) </div> <h2>Project status and work for iteration 3</h2> <p>Based on the previous two iterations, all we have left from the original list is the "feature squares" (the snakes and ladders style squares):</p> <ol> <li><strike>A player can roll the die, and then move that many spaces along the board.</strike></li> <li>A player that ends his or her turn on a "feature square" (a square containing a creature or obstacle), will be moved to the square connected with that feature.</li> <li><strike>There can be 1-4 players, and each player has their turn in sequence.</strike></li> <li><strike>A player that reaches the final square wins the game.</strike></li> </ol> <p>We'll leave the pending story on hold for now so we can get to the GUI bits. One thing to notice is that none of these stories, strictly speaking, demand a GUI. So let's add one, in consultation with our customers (i.e. firstborn and I):</p> <ol start="5"> <li>Each player's position will be displayed on an 8 x 8 grid of squares.</li> </ol> <p>This should give us enough to get rid of the command line demo code and give the customer something closer to a usable product. It will probably be enough to fill the whole iteration as well, as we may have to revisit some of the original stories and make sure we have exposed them all through our GUI (story 1 for example). I've also managed to miss a fairly major part of story 3 -- there is currently no way to choose how many players there are in the game.</p> <p>I think this indicates a problem with the approach so far. Imagine having to revisit every story after implementing 50 or so due to a change to the front end. One big thing we are missing that could help us avoid this are acceptance tests. If we had those, the relevant ones would fail and we could test drive out our way back to green. It could also be an indication that we have too much logic in the untested demo app. We were aware of this when we wrote the demo app though, and never intended to keep it around long enough for it to become a problem, so manually rechecking our 3 finished stories shouldn't be too big a deal.</p> <p>Let's start off using WPF for this, as it's shiny and new (well, compared with standard WinForms), and comes standard with our current .NET 3.5 platform. We'd obviously want to do some more research if doing this for real. I've done practically nothing with WPF to date, so I'm looking forward to publicly humiliating myself throughout the remainder of this post. (Why don't my regular readers look surprised? ;))</p> <h2>Where to start?</h2> <p>I'd like to replace our untested demo code with tested, production code that we can use as a foundation for a GUI. We need to make sure the functionality of our original stories are exposed via the GUI, rather than the demo app. The two things that jump out at me is that we need a way for a player to roll a die, and we also need some way to indicate the end of the game. The actual rules of the game are hopefully captured in our <code>Game</code> class, so with a bit of luck we'll only need to verify our UI's interaction with that class. Then to complete our story we'll need to make sure each player's position is displayed on the game board.</p> <p>I'd love to avoid jumping straight to an MVP-style pattern here, in favour of starting from first principles and refactoring to patterns like that when it becomes painfully obvious we need to. However I have absolutely no idea how to do that test-first, so let's try the standard route of creating a <code>GamePresenter</code> that will mediate between our <code>Game</code> model and our UI. We'll start off with the basics of rolling the die and move on from there.</p> <h2>Rollin', rollin', rollin'</h2> <p>What should happen when a player interacts with the view to roll the die? Well for starters our model class, <code>Game</code>, should probably be updated to reflect the fact the player is having their turn. We don't have an actual GUI button to press, but we know that we can fire off an event when a GUI button is clicked. If we add this event to a view interface, and our real GUI implements that interface, then we'll be able to write automated tests for large number of interactions with our GUI via its interface. Our GUI implementation itself should be fairly basic and concentrate on rendering and widgets rather than application logic (see the <a href="">Humble Dialog Box</a> [PDF]).</p> <pre> public class GamePresenterSpec { [Fact] public void Game_should_update_when_roll_die_is_clicked() { var fakeGameView = MockRepository.GenerateStub<IGameView>(); var fakeGame = MockRepository.GenerateMock<IGame>(); var gamePresenter = new GamePresenter(fakeGameView, fakeGame); fakeGameView.Raise(view => view.RollClicked += null, this, EventArgs.Empty); fakeGame.AssertWasCalled(game => game.Roll(Arg<int>.Is.Anything)); } } </pre> <p>This test isn't really saying much, just that <code>game.Roll(...)</code> should be called with any argument, which is how a player currently has their turn in our model. We need to extract an <code>IGame</code> interface for this, and also create an <code>IGameView</code> and a <code>GamePresenter</code>.</p> <pre> public class GamePresenter { public GamePresenter(IGameView view, IGame game){} } public interface IGameView { event EventHandler RollClicked; } public interface IGame { void Roll(int dieValue); } </pre> <p>Our test compiles, but fails. We'll fix that now.</p> <pre> public class GamePresenter { private readonly IGame _game; public GamePresenter(IGameView view, IGame game) { _game = game; view.RollClicked += view_RollClicked; } void view_RollClicked(object sender, EventArgs e) { _game.Roll(1); } } </pre> <p>Our test now passes, and as I can't see much refactoring to do, let's try the next test. Looking at what we have so far, the most obvious deficiency to me seems to be that we are just rolling 1 in the game. We really need a die roll here (1d6 :)), but that would involve random numbers running around our tests causing havoc. So let's fake a <code>DieRoller</code> that we can use to get known values during tests, and random values during the actual game.</p> <pre> public class GamePresenterSpec { private IGameView fakeGameView; private IGame fakeGame; private IDieRoller fakeDieRoller; private GamePresenter CreateGamePresenterAndDependencies() { fakeGameView = MockRepository.GenerateStub<IGameView>(); fakeGame = MockRepository.GenerateMock<IGame>(); fakeDieRoller = MockRepository.GenerateStub<IDieRoller>(); return new GamePresenter(fakeGameView, fakeGame, fakeDieRoller); } / ... snip ... / [Fact] public void Game_should_roll_value_from_die_when_roll_die_is_clicked() { CreateGamePresenterAndDependencies(); int dieFace = 3; fakeDieRoller.Stub(die => die.Roll()).Return(dieFace); RaiseRollClickedEventOnView(); fakeGame.AssertWasCalled(game => game.Roll(dieFace)); } private void RaiseRollClickedEventOnView() { fakeGameView.Raise(view => view.RollClicked += null, this, EventArgs.Empty); } } </pre> <p>The new test stubs out a known value for <code>IDieRoller.Roll()</code>, then makes sure that will get passed to our <code>Game</code>. I've also shown that we've extracted the common fixture setup code into a <code>CreateGamePresenterAndDependencies()</code> method, although we'd normally do this refactoring after all the tests get to green (unfortunately this stuff is surprisingly difficult to get into blog-form, so please excuse me taking some licence with presentation).</p> <pre> public class GamePresenter { private readonly IGame game; private readonly IDieRoller roller; public GamePresenter(IGameView view, IGame game, <b>IDieRoller roller</b>) { this.game = game; this.roller = roller; view.RollClicked += view_RollClicked; } void view_RollClicked(object sender, EventArgs e) { <b>game.Roll(roller.Roll());</b> } } public interface IDieRoller { int Roll(); } </pre> <p>And we're back at green. What else can we look at? Well we should probably display the result of the roll to the player. Like our <code>view.RollClicked</code> event, we'll just make our view interface have a method for setting the result of a die roll (say, <code>ShowRollResult(dieFace)</code>), and we'll let our actual GUI implementation worry about translating this message to the display.</p> <pre> [Fact] public void View_should_show_result_of_roll() { CreateGamePresenterAndDependencies(); int dieFace = 2; fakeDieRoller.Stub(die => die.Roll()).Return(dieFace); RaiseRollClickedEventOnView(); fakeGameView.AssertWasCalled(view => view.ShowRollResult(dieFace)); } </pre> <pre> public class GamePresenter { private readonly IGameView view; / ... snip ... / void view_RollClicked(object sender, EventArgs e) { <b>var dieValue = roller.Roll();</b> game.Roll(dieValue); <b>view.ShowRollResult(dieValue);</b> } } </pre> <h2>Whose turn is it anyway?</h2> <p>Tests pass, and can't see any refactoring to do. It is probably important to show whose turn it is, so let's try that now. First up, we need to show the current player when the game is first started.</p> <pre> [Fact] public void View_should_show_current_player_when_game_is_created() { CreateGamePresenterAndDependencies(); var currentPlayer = 1; fakeGame.Stub(game => game.CurrentPlayer).Return(currentPlayer); fakeGameView.AssertWasCalled(view => view.SetCurrentPlayer(currentPlayer)); } </pre> <p>Oops, this won't work. We are using <code>CreateGamePresenterAndDependencies()</code> to create everything in one step, but then we go on to stub out the <code>game.CurrentPlayer</code> call. Let's separate the dependency creation from the creation of the subject under test.</p> <pre> [Fact] public void View_should_show_current_player_when_game_is_created() { <b>CreateGameDependencies();</b> var currentPlayer = 1; fakeGame.Stub(game => game.CurrentPlayer).Return(currentPlayer); <b>new GamePresenter(fakeGameView, fakeGame, fakeDieRoller);</b> fakeGameView.AssertWasCalled(view => view.SetCurrentPlayer(currentPlayer)); } </pre> <div class="note"><b>Note:</b> this kind of mucking around with the fixture is a drawback of using a fixture-per-class style of test organisation. This seems to be how most people start TDD (myself included), but I think using a fixture-per-scenario approach (more of a BDD style) is easier to use and probably to learn from. I'm using a more BDD-like approach for my real code now, and am finding it generally makes TDD much easier. I still haven't got it right yet though, so both for that reason and for consistency I'll stick with fixture-per-class for this post.</div> <p>To get this passing we'll need to pull up <code>Game.CurrentPlayer</code> to the <code>IGame</code> interface, then update the <code>GamePresenter</code> constructor to pass this information to the view.</p> <pre> public GamePresenter(IGameView view, IGame game, IDieRoller roller) { this.view = view; this.game = game; this.roller = roller; view.RollClicked += view_RollClicked; <b>view.SetCurrentPlayer(game.CurrentPlayer);</b> } </pre> <p>That handles the start of the game, but we also need to change whose turn it is after each roll.</p> <pre> [Fact] public void View_should_show_current_player_after_a_roll() { CreateGamePresenterAndDependencies(); var player = 2; fakeGame.Stub(game => game.CurrentPlayer).Return(player); RaiseRollClickedEventOnView(); fakeGameView.AssertWasCalled(view => view.SetCurrentPlayer(player)); } / In GamePresenter: / void view_RollClicked(object sender, EventArgs e) { var dieValue = roller.Roll(); game.Roll(dieValue); view.ShowRollResult(dieValue); <b>view.SetCurrentPlayer(game.CurrentPlayer);</b> } </pre> <div class="note"><b>Ugh:</b> Looking back through my notes while I'm typing this up, I have something to the effect of "Seems ugly. Using WPF, shouldn't I be binding to the ViewModel/PresentationModel?". This is fairly important -- I'm going to blatantly end up misusing WPF in this case because I'm not taking advantage of any of the nice databinding features it has. Let's press on though, if for no reason other than to point at the author and laugh at his incompetence. Maybe we can salvage what we have later on.</div> <h2>Where am I?</h2> <p>Ostensibly the story we are working on is to display each player's position on the grid. It should not be too hard to update each player's position after they take their turn. Because I haven't done enough of a spike to see how our view should work, let's just assume we have a <code>MovePlayerMarker(...)</code> method on the view that will handle any animation or display stuff we need.</p> <pre> [Fact] public void Should_update_players_position_after_roll() { CreateGamePresenterAndDependencies(); var player = 1; var newSquare = 10; var oldSquare = 5; fakeGame.Stub(game => game.CurrentPlayer).Return(player); fakeGame.Stub(game => game.GetSquareFor(player)).Return(oldSquare); fakeGame.Stub(game => game.GetSquareFor(player)).Return(newSquare); RaiseRollClickedEventOnView(); fakeGameView.AssertWasCalled(view => view.MovePlayerMarker(player, oldSquare, newSquare)); } / In GamePresenter: / void view_RollClicked(object sender, EventArgs e) { var dieValue = roller.Roll(); <b>var player = game.CurrentPlayer;</b> <b>var startingSquare = game.GetSquareFor(player);</b> game.Roll(dieValue); view.ShowRollResult(dieValue); view.SetCurrentPlayer(player); <b>view.MovePlayerMarker(player, startingSquare, game.GetSquareFor(player));</b> } </pre> <p>We are really starting to run into some of the limitations of our <code>Game</code> class now. As soon as a player rolls the die in the game, the positions and current player changed, so we need to save this information prior to calling <code>game.Roll(...)</code>. This may indicate we may have an overly intimate implementation. We need to know all kinds of stuff about the <code>Game</code> implementation to use it, which is making our <code>view_RollClicked(...)</code> code fairly ugly as it steps through the procedure of running the game. Maybe we should instead expose a list of player positions that we could bind to instead?</p> <p>It looks like we are due for some refactoring, but I'm not really sure how to proceed with that. Instead of letting that hold us up as we worry about all the potential solutions we could pick, let's put that off and whack up a quick view implementation and see if that helps at all.</p> <h2>This time I'm playing to win!</h2> <p>Before we make that final step to the GUI implementation we still need to handle one more case from our original console app -- winning the game. Here's two tests and an implementation that passes them both (although written one at a time, of course!).</p> <pre> [Fact] public void Should_show_winner_when_game_is_finished() { CreateGamePresenterAndDependencies(); int player = 3; fakeGame.Stub(game => game.CurrentPlayer).Return(player); fakeGame.Stub(game => game.IsFinished).Return(true); RaiseRollClickedEventOnView(); fakeGameView.AssertWasCalled(view => view.ShowWinner(player)); } [Fact] public void Should_disable_die_roll_when_game_is_finished() { CreateGamePresenterAndDependencies(); fakeGame.Stub(game => game.IsFinished).Return(true); RaiseRollClickedEventOnView(); fakeGameView.AssertWasCalled(view => view.DisableDieRolls()); } / In GamePresenter: / void view_RollClicked(object sender, EventArgs e) { var dieValue = roller.Roll(); var player = game.CurrentPlayer; var startingSquare = game.GetSquareFor(player); game.Roll(dieValue); view.ShowRollResult(dieValue); view.SetCurrentPlayer(player); view.MovePlayerMarker(player, startingSquare, game.GetSquareFor(player)); <b>if (game.IsFinished) { view.DisableDieRolls(); view.ShowWinner(player); }</b> } </pre> <h2>The worst, most blatant misuse of WPF in history!!!1!</h2> <p>I'm not proud of what you are about to see. In fact, I'm rarely proud of any of the crud I write on this blog, but if my normal stuff is a 2 out of 10, this is about a -30 10<sup>12</sup>. My local check-in comment for this stuff is "Embarrassingly bad GUI using WPF controls", which is pretty accurate. I'm using WPF controls, but saying this is WPF is like wrapping a 1000 line main method in a class declaration and calling it OO. But I did promise a GUI of sorts, so let's try and get something graphical working.</p> <div class="note"><b>Don't do this!</b> In case you missed my subtle hints throughout this post, don't repeat what you are about to see. It would be pure evil if it weren't for its lack of competence. Don't bother donning the goggles, they'll do nothing.</div> <p>First, I've created a new <code>DaveSquared.GardenRace.Gui</code> WPF project to house this hideous monstrosity. I've created a new WPF form called <code>GardenRaceView</code>. Here's the XAML.</p> <pre> <Window x: <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="528" /> <ColumnDefinition Width="166" /> </Grid.ColumnDefinitions> <UniformGrid Name="gameBoard" Rows="8" Columns="8" /> <Label Grid.currentPlayer</Label> <Button Grid.Roll</Button> <Label Grid.rollResult</Label> <Ellipse Visibility="Hidden" Name="player1Marker" Stroke="Black" Height="30" Margin="5, 0, 0, 0" HorizontalAlignment="Left" VerticalAlignment="Top" Fill="Red" Width="30" /> <Ellipse Visibility="Hidden" Height="30" HorizontalAlignment="Left" Name="player2Marker" Stroke="Black" Fill="Blue" VerticalAlignment="Top" Width="30" /> </Grid> </Window> </pre> <div class="separator" style="clear: both; text-align: center;"> <a href="" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="" style="cursor: move;" alt="The game screen in VS 2008's design view. It looks even worse when running for real!" title="The game screen in VS 2008's design view. It looks even worse when running for real!" /></a> </div> <p>This gives us two columns to work with: The left hand column to hold the board, and the right hand column for status and game controls. Let's wire this thing up. Here is the xaml.cs file. This was originally wired up piece by piece, manually testing in between (we don't have automated tests for the view remember).</p> <pre> public partial class GardenRaceView : Window, <b>IGameView</b> { public GardenRaceView() { InitializeComponent(); FillSquares(); MoveToStartingPositions(); <b>var gameModel = new Game(64, 2); new GamePresenter(this, gameModel, new DieRoller());</b> } private void MoveToStartingPositions() { MovePlayerMarker(1, 0, 0); MovePlayerMarker(2, 0, 0); } private void FillSquares() { for (var squareNumber=1; squareNumber <= 64; squareNumber++) { var square = new StackPanel(); var squareLabel = new Label(); squareLabel.Content = squareNumber; square.Children.Add(squareLabel); gameBoard.Children.Add(square); } } public event EventHandler RollClicked; private void OnRollClicked() { EventHandler rollClickedHandler = RollClicked; if (rollClickedHandler != null) <b>rollClickedHandler(this, EventArgs.Empty)</b>; } <b>public void ShowRollResult(int dieFace) { rollResult. <a href="" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="292" src="" style="cursor: move;" width="400" alt="Screen shot from the game." title="Screen shot from the game. While WPF is meant to make beautiful GUIs easier to make than ever before, it's great to see some people still manage to produce complete garbage. On the positive side, I think this one is still better than Lotus Notes. :)" /></a></div> <h2>On what poor, pitiful, defenseless customers has my monstrosity been unleashed?</h2> <p>So what have we done? Besides unsubscribing from Dave's blog, we also managed to test drive a presenter and unleash a hideous GUI on our unsuspecting customers. We've done a very rough job on this story (my fault, not yours), but we are now displaying players' positions on a grid. The grid is not in the correct order for a snakes and ladders-style game (it is meant to snake around, starting at the bottom of the board and winding its way up to the top), but we can refine this later. We've also replaced our untested, console-only demo app with a tested, hideous bastardisation of WPF.</p> <p>We've also found lots of new tasks to do. First, learn WPF. Next, refactor this to have a more useful <code>Game</code> class, and maybe change the presenter into more of a presentation model approach so we can use some WPF goodness. We also need to do something about our incomplete story about being able to play with 1 - 4 players -- at present we have 2 players hard coded in. And we also should put in some snake and/or ladder-like squares.</p> <p>Despite the obvious problems with the current code, I'd like to try and salvage some small glimmer of positivity from this post. We managed to test drive a whole host of GUI-specific functionality, before we even had a forms project. We managed to hook in a thin view on top of that foundation that, despite being ugly, just worked. (Really it did! If I was going to start lieing to you it would have been in an attempt to hide my incompetence during the rest of the post, not for something trivial like this ;)). And last but not least -- um, no, actually they're the only positives I can think of. :)</p> <p>I hope you can get some value from this post, even if its just a laugh or two at my expense. :) I'd love to hear your thoughts as to whether what we've got here is salvageable, and if so then how you would start evolving it in the right direction. In the meantime, I'm off to <a href="">read up on WPF< a class for making asynchronous calls<p>In my <a href="">last post</a> I looked at doing all kinds of evil things to get some legacy code under test. The code in question launched a new thread to do some work, and I ended up wrapping this asynchronous call in a <code>ThreadDispatcher</code> class for testing.</p> <pre> public class <b>ThreadDispatcher</b> { public AsyncCall Dispach(Action function) { var thread = new Thread(() => function()); thread.Start(); <b>return new AsyncCall(thread);</b> } } public class AsyncCall { private readonly Thread _thread; public AsyncCall(Thread thread) { _thread = thread; } public void WaitUntilCallFinishes() { _thread.Join(); } } </pre> <p>I could then test the dispatcher like this:</p> <pre> [Test] public void RunsFunctionFromDifferentThread() { var dispatcher = new ThreadDispatcher(); int callingThreadId = Thread.CurrentThread.ManagedThreadId; int dispatchedThreadId = callingThreadId; var asyncCall = dispatcher.Dispach(() => dispatchedThreadId = Thread.CurrentThread.ManagedThreadId); <b>asyncCall.WaitUntilCallFinishes();</b> Assert.That(dispatchedThreadId, Is.Not.EqualTo(callingThreadId)); } </pre> <p>There's (at least) two problems with this. First, the return value of this function is a complete contrivance for the sake of testability (so our tests can call <code>asyncCall.WaitUntilCallFinishes()</code> <code>ThreadPool</code> to run the work in the background then we don't get a reference to a <code>Thread</code>, and therefore can't wait on it.</p> <h2>A neater approach</h2> <p:</p> <pre> public class AsynchronousDispatcher { public void Execute(Action action) { ThreadPool.QueueUserWorkItem(state => action()); } } </pre> <p>The fun part is the tests. Seeing as we've removed the concept of waiting from our implementation, this has to be handled from our tests instead. Which is fine, because the tests are the only place we need this functionality.</p> <pre> ) { <b>var resetEvent = new AutoResetEvent(false);</b> var dispatcher = new AsynchronousDispatcher(); dispatcher.Execute(() => { action(); <b>resetEvent.Set();</b> }); <b>resetEvent.WaitOne();</b> } </pre> <p>You'll see that the tests themselves are almost identical to the ones from last time, as most of the hard work is done in the <code>DispatchToThreadAndWaitUntilDone(Action action)</code> function. This uses an <code>AutoResetEvent</code> to handle synchronisation, and signals (<code>resetEvent.Set()</code>) as part of the work being done on our new thread. While the new thread is busy doing its asynchronous thang, the thread running our test uses <code>WaitOne()</code>.</p> <p>So now we've got a trivial and tested implementation we can use to make asynchronous calls. If we extract an interface (or make <code>Execute(...)</code> virtual) we can easily mock this or replace it with a synchronous implementation to test classes that need to use <code>AsynchronousDispatcher</code>.</p> <p>Apologies if this is all a bit simplistic, but I thought the tests looked kinda neat so I thought I'd share. Feel free to rip gigantic holes in it legacy code when simple threading's involved<p>A good friend and "former colleague in (an) archaic dev team" (his words :)) recently sent me a problem he was having testing some code he inherited. The code seemed to work during manual testing, but threw exceptions when being tested using NUnit under certain conditions. Let's look at a drastically modified example of the code:</p> <pre> [TestFixture] public class BigImportantClassFixture { [Test] public void CanGetKnownEmployee() { var existingEmployeeId = Guid.Empty var importantClass = new BigImportantClass(); var employee = importantClass.GetEmployee(existingEmployeeId); Assert.That(employee.Name, Is.EqualTo("Bilbo")); } } public class BigImportantClass { <b>public Employee GetEmployee(Guid employeeID) { Employee employee = EmployeeRepository.GetEmployeeByID(employeeID); Logging.AsyncLog("Called GetEmployeeByID"); return employee; }</b> } public static class Logging { public static void AsyncLog(string message) { <b>var thread = new Thread(Log); thread.Start(message);</b> } private static void Log(object message) { //Write line to log. This op may take some time Thread.Sleep(1000); Console.WriteLine(message); } } </pre> <p>Can you guess the exception that cropped up? The unit test runner tears down the app domain it uses to run the fixtures when it is finished. Because the code spawns a new thread, this means that if that thread is still running it gets aborted as the app domain exits, so we get a <code>ThreadAbortException</code>. So how can we get this under test?</p> <h2>Questioning the approach</h2> <p>I think it would be remiss of us not to spend some time considering why we are using this approach. Is <code>GetEmployee()</code> called a lot and so needs to be fast? Will the added burden of spinning up another thread per call help, or will it hinder overall performance due to the increased load on the system? Would we be better off with a synchronous call? Do we even need logging here? Have we looked at using <a href="">AOP for logging</a>? Can libraries like <a href="">log4net</a> handle asynchronous logging for us? Or should we implement our own queue and have that serviced by threads that can work on processing the logs in batches? Should we be using background threads from the <code>ThreadPool</code>? Should we look at message queuing? Are static methods and opaque dependencies like this a work of pure evil? And if you were a tree, what tree would you be?</p> <p>These are all good questions to ask and something my mate is looking into (I think he's leaning toward the larch). For the rest of this post however, I'd like to concentrate on how we could get this code under test. The code currently seems to work, but we don't have automated tests covering it, so we'll try and keep code changes small to give us confidence we aren't breaking anything during the process. This means we'll try and avoid changes ripping out the dependencies and using constructor injection. <a href="">Once it's under test, we can worry about making it purdy</a> and move on to more complex refactorings, and maybe even change the whole logging implementation once we decide which approach to use.</p> <h2>Isolating the logging behaviour in <code>GetEmployee()</code></h2> <p>Our <code>GetEmployee</code> method does two things: looks up an <code>Employee</code> and does some logging. We already have the beginning of a test for the employee lookup part, but the coupling to the logging functionality is causing some problems. It is also untested. Let's write a test that isolates the behaviour.</p> <pre> [Test] public void GetEmployeeCallIsLogged() { var mockLogger = MockRepository.GenerateMock<ILogger>(); Logging.SetLogger(mockLogger); var importantClass = new BigImportantClass(); importantClass.GetEmployee(Guid.Empty); mockLogger.AssertWasCalled(mock => mock.AsyncLog(Arg<String>.Is.Anything)); } </pre> <p>Normally I'd look at constructor injection for this sort of thing, but we're aiming for minimal modifications to the original code. Logging is also a bit of a special case — you potentially need it everywhere and so you may not want to explicitly put <code>ILogger</code> objects into every single object you have.</p> <p>To pass this test, we'll need to extract an <code>ILogger</code> interface from our static <code>Logger</code> class, and change the implementation to use a Singleton approach (so we can override the behaviour by changing the instance).</p> <pre> public interface ILogger { void AsyncLog(string message); } public class Logging : ILogger { <b>private static ILogger instance = new Logging(); public static void SetLogger(ILogger logger) { instance = logger; }</b> public static void AsyncLog(string message) { <b>instance.AsyncLog(message);</b> } private static void Log(object message) { //Write line to log. This op may take some time Thread.Sleep(1000); Console.WriteLine(message); } void ILogger.AsyncLog(string message) { var thread = new Thread(Log); thread.Start(message); } } </pre> <p>This passes our test. Notice we've made virtually no changes to the pre-existing code and only a few minor additions. We've added a singleton instance and a trivial <code>SetLogger()</code> method, and moved the code previously in the static <code>AsyncLog()</code> method into the <code>ILogger.AsyncLog()</code> instance method, with the static methods delegating to the instance one. We haven't had to change the <code>GetEmployee()</code> method at all. Hopefully this means we haven't broken anything. A quick manual test verifies that everything is working as before.</p> <p>I'm a bit worried that we might replace the singleton instance with something evil during one test and inadvertently cause another test to break, but I guess that's a price of using singletons. At this point we just want to get the code under test before we go trying to make it all purdy. On the positive side, we can now test the employee lookup functionality independently of the logging, including testing that <code>GetEmployee()</code> invokes the logging call as required.</p> <h2>An integration test for logging</h2> <p>We've isolated our logging behaviour and tested it is called correctly from <code>GetEmployee()</code>, which means we can now write a test to make sure our logging works when it is called.</p> <pre> [TestFixture] public class LoggingFixture { [Test] public void AsyncLogShouldDoFunkyLoggingStuff() { ILogger logging = new Logging(); logging.AsyncLog("some message"); Thread.Sleep(2000); //AssertDesiredSideEffectOccurred(); } } </pre> <p>Because of our previous efforts we can work directly with a <code>Logging</code> instance, rather than through the static methods. We still have a problem though. We want to check that whatever effect <code>AsyncLog()</code> has occurred properly, but because it is called asynchronously we have to put in a hacky <code>Thread.Sleep()</code> to make sure it is done. There are a few problems with this approach. Firstly, how do we know 2000 ms is enough? We might have our test intermittently breaking, which is a huge no-no. Secondly, it will make our tests run slow.</p> <h2>Isolating our threading problem</h2> <p>We'd really like the option of using <code>Thread.Join()</code> or similar so our test can wait on the asynchronous operation to finish. But we currently don't have any way to access the threading part of the operation.</p> <p>One way to solve this problem is to implement the <a href="">Asynchronous Programming Model</a>. This lets the operation to be called asynchronously and waited on using polling/spin loop, call back or wait handle. Unfortunately it also looks like quite a lot of work, and a large amount of change to make without tests.</p> <p>Another possible solution is to isolate the threading behaviour from the logging operation, just as we did for separating the employee lookup from the logging. Let's try that — we'll write a class that specialises in running a function in a new thread.</p> <pre> [TestFixture] public class ThreadDispatcherFixture { [Test] public void CanRunFunctionCall() { var dispatcher = new ThreadDispatcher(); bool wasRun = false; dispatcher.Dispach(() => wasRun = true); Assert.That(wasRun); } } public class ThreadDispatcher { public void Dispach(Action function) { function(); } } </pre> <p>This passes. Let's expand our test fixture, and try a naive implementation:</p> <pre> [Test] public void RunsFunctionFromDifferentThread() { var dispatcher = new ThreadDispatcher(); int callingThreadId = Thread.CurrentThread.ManagedThreadId; int dispatchedThreadId = -1; dispatcher.Dispach(() => dispatchedThreadId = Thread.CurrentThread.ManagedThreadId); Assert.That(dispatchedThreadId, Is.Not.EqualTo(callingThreadId)); } //... public class ThreadDispatcher { public void Dispach(Action function) { var thread = new Thread(() => function()); thread.Start(); } } </pre> <p>This passes the new <code>RunsFunctionFromDifferentThread()</code> test, but luckily fails the original <code>CanRunFuctionCall()</code> test when run on my machine. I say luckily because it is timing dependent — the thread has not completed by the time the <code>Assert.That(wasRun)</code> executes. If you slip in a <code>Thread.Sleep(...)</code> for a few milliseconds you'll see both tests pass as the async thread starts to win our race condition.</p> <p>This is a really good illustration that test coverage does not equal correctness, nor is it an excuse to avoid thinking :). Given we've thought about the problem though, TDD can help lead us to a solution. We need to make sure our async thread has run before we call our assert, so let's ammend our tests to show this:</p> <pre> [Test] public void CanRunFunctionCall() { var dispatcher = new ThreadDispatcher(); bool wasRun = false; var dispatchedThread = dispatcher.Dispach(() => wasRun = true); <b>dispatchedThread.Join();</b> Assert.That(wasRun); } [Test] public void RunsFunctionFromDifferentThread() { var dispatcher = new ThreadDispatcher(); int callingThreadId = Thread.CurrentThread.ManagedThreadId; int dispatchedThreadId = callingThreadId; var dispatchedThread = dispatcher.Dispach(() => dispatchedThreadId = Thread.CurrentThread.ManagedThreadId); <b>dispatchedThread.Join();</b> Assert.That(dispatchedThreadId, Is.Not.EqualTo(callingThreadId)); } </pre> <p>And a reliably passing implementation (I hope):</p> <pre> public <b>Thread</b> Dispach(Action function) { var thread = new Thread(() => function()); thread.Start(); <b>return thread;</b> } </pre> <p>It may not be a good idea to pass a reference to the <code>Thread</code> back, so it might be neater to wrap the <code>Join()</code> functionality in a new class (with tests updated accordingly).</p> <pre>(); } } </pre> <p>This is all new code, so we shouldn't have broken anything that was working in our original implementation.</p> <h2>Bringing logging and threading back together</h2> <p>Now we've separated logging and threading, we need to bring them back together so this thing actually works as required. Let's jump into our <code>LoggingFixture</code>:</p> <pre> [TestFixture] public class LoggingFixture { [Test] public void AsyncLogShouldDoFunkyLoggingStuff() { ILogger logging = new Logging(new ThreadDispatcher()); logging.AsyncLog("some message"); Thread.Sleep(2000); //AssertDesiredSideEffectOccurred(); } [Test] public void AsyncLogShouldUseThreadDispatcher() { var dispatcher = MockRepository.GenerateMock<ThreadDispatcher>(); ILogger logging = new Logging(dispatcher); logging.AsyncLog("some message"); dispatcher.AssertWasCalled(x => x.Dispach(null), options => options.IgnoreArguments()); } } public class Logging : ILogger { private readonly ThreadDispatcher dispatcher; private static ILogger instance = new Logging(new ThreadDispatcher()); <b>public Logging(ThreadDispatcher dispatcher) { this.dispatcher = dispatcher; }</b> public static void SetLogger(ILogger logger) { instance = logger; } public static void AsyncLog(string message) { instance.AsyncLog(message); } private static void Log(object message) { //Write line to log. This op may take some time Thread.Sleep(1000); Console.WriteLine(message); } void ILogger.AsyncLog(string message) { <b>dispatcher.Dispach(() => Log(message));</b> } } </pre> <p>This has probably been the most radical change to our code. We've changed the implementation of <code>AsyncLog</code> to delegate the threading to our new <code>ThreadDispatcher</code>. We've also added some dependency injection, using the <code>Logging</code> constructor to pass in our <code>ThreadDispatcher</code>. Everything is green. Even better, we can now update the original <code>AsyncLogShouldDoFunkyLoggingStuff()</code> and test the logging behaviour in isolation.</p> <pre> [TestFixture] public class LoggingFixture { private class FakeThreadDispatcher : ThreadDispatcher { public override AsyncCall Dispach(Action function) { function(); return new AsyncCall(null); } } [Test] public void AsyncLogShouldDoFunkyLoggingStuff() { ILogger logging = new Logging(new FakeThreadDispatcher()); logging.AsyncLog("some message"); //No more Thread.Sleep(...) here. Our FakeThreadDispatcher will do a synchronous call. //AssertDesiredSideEffectOccurred(); } //... } </pre> <p>You could also do some fancy mockFu for this, but in this case I think it's easier to hand code a <code>FakeThreadDispatcher</code> (if changes to the base class cascade down to our fake and it starts getting painful we can switch a generated mock or stub).</p> <h2>Conclusion</h2> <p>Our <code>Logging</code> implementation only calls <code>Console.WriteLine()</code>, so for our <code>AssertDesiredSideEffectOccurred()</code> we would need to fake that out. We won't go that far down the rabbit hole though, as the real logging implementation would be probably do all kinds of exciting things that we could test. The point is that we can now test the logging in isolation from our threading. Our threading code is also tested, and we can test our original employee look up too (by setting a stub <code>ILogger</code> when testing <code>BigImportantClass</code>).</p> <p>Best of all, the only really changes of any consequence we made to our original code is implementing a singleton <code>Logging</code> instance and extracting the thread launching code to a new class. So, from a unit testing point of view, we have gained a lot for very little risk.</p> <p>This was a very simple bunch of refactorings to perform. I hope that came across during the post, but sometimes these things don't translate well to post format. If that's the case then try picking up the code from the start of this post and go through the process of getting it under test.</p> <p>As always feel free to pick holes in this post and let me know via comment or email. PowerShell prompt<p>Today a <a href="">colleague</a> sent around an interesting link on how to put your <a href="">git status in your bash prompt</a>. I thought I'd spend a few minutes trying to get a similar effect in PowerShell (v2 CTP3). It's not particularly useful, but I found it an interesting exercise. Here's what I came up with, saved in <code>GitAwarePrompt.ps1</code>. <b>Disclaimer:</b> I know nothing about PowerShell so use anything from this post at your own risk. :) </p> <pre> function Get-GitBranchNameWithStatusIndicator { $statusOutput = Invoke-Expression 'git status 2>$null' <b>#1</b> if (!$statusOutput) { return } <b>#2</b> $branch = $statusOutput[0] <b>#3</b> if ($branch -eq "# Not currently on any branch.") { $") -nonewline return " " } </pre> <p>I've put some numbered comments on a couple of lines so we can go through the main parts of the script, or you can skip to the next heading if you just want to try out the script.</p> <p>Line #1 uses the <code>Invoke-Expression</code> commandlet to run the <code>git status</code> command and store the output in the local <code>$statusOutput</code> variable. We are using <code>2>$null</code> to drop any output written to standard error, otherwise whenever we try and write a prompt in a non-git directory we'll get a git error message appearing. You'll also notice we have the <code>git status 2>$null</code> command surrounded by single quotes ('), rather than double quotes ("). The reason is that PowerShell automatically performs variable substitution within double quoted strings. So if we used double quotes the <code>$null</code> would be replaced by with nothing (it's current value), which will cause us no end of problems (go on, ask me how I know! :)). </p> <p>If the <code>git status</code> command errors out (say, if the current directory is not in a git repo), then <code>$gitStatus</code> will be null. Line #2 checks for this and returns void if <code>$statusOutput</code> is undefined. Otherwise <code>$statusOutput</code> will an array of objects, with an item for each line of the command output. Line #3 grabs the first line of output, which contains a string which contains our branch name, and stores it in a variable. The <code>if/else</code> that follow checks first to make sure we are actually on a branch, and parses the branch name from the line.</p> <p>Line #4 was a nice surprise for me -- PowerShell supports wrapped array indexing! Using an index of <code>-1</code> grabs the last item in the array. Very pythonesque :). Line #5 then compares this with the output <code>git status</code> gives when there are no changes, and the rest of the <code>if/else</code> block sets the <code>$statusIndicator</code> based on this result. (No <a href="">built in ternary operator</a> apparently.)</p> <p>Finally, line #6 defines a <code>prompt</code> function, which PowerShell uses to write it's prompt.</p> <h2>Using the script</h2> <p>If we just run this script from within PowerShell it will do absolutely nothing. The reason is because any functions or variables defined will be cleaned up when the script exits. To change the scope and affect the current environment we need to <a href="">dot-source</a> the script, like this (depending on where you saved the script):</p> <pre> PS > . $HOME/Documents/WindowsPowerShell/GitAwarePrompt.ps1 </pre> <p>Without the dot and space, you get nothing. With the dot-sourced script, we have created a <code>prompt</code> function for PowerShell to call, and we get the status of our Git working directory from our command line:</p> <pre> PS C:\Development\git\HelloWorld <b>[helloGit]</b>> "Modify hello.txt" > hello.txt PS C:\Development\git\HelloWorld <b>[helloGit]</b>> git commit -a -m "Commit change" [helloGit]: created 8a7947c: "Commit change" 1 files changed, 0 insertions(+), 0 deletions(-) PS C:\Development\git\HelloWorld <b>[helloGit]</b>> git checkout master Switched to branch "master" PS C:\Development\git\HelloWorld <b>[master]</b>> "Change hello.txt again" > hello.txt PS C:\Development\git\HelloWorld <b>[master]</b>> PS C:\Development\git\HelloWorld <b>[master]</b>> cd .. PS C:\Development\Git> </pre> <h2>Setting the default prompt</h2> <p>You can also more permanently modify your PowerShell prompt by putting the script in your PowerShell profile, which is set to something like <code>~\Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1</code> by default (if it doesn't exist, you can create it from PowerShell using <code> New-Item $PROFILE -ItemType file -Force</code>). This can be something like the Git-aware prompt shown here, or something <a href="">more interesting</a>. Be careful you don't slow down your shell too much though: <code>prompt</code> is obviously called on every new up diff and merge tools for Git on Windows<p>I <a href="">Git on MSys</a> to get Git working on Windows via a PowerShell command line, but a similar setup might work via Cygwin or via the <code>cmd.exe</code> command line.</p> <h2>Setting up a diff tool</h2> <div class="note"><b>Update 2009-05-20:</b> This approach stopped working for me when I upgraded to Windows 7 and Git 1.6.3. I had to <a href="">switch to using <code>git difftool</code> instead</a>.</div> <p>The easiest way I found to do this was to create a shell script wrapper for your diff tool of choice. To make things easy on me I put the script, <code>git-diff-wrapper.sh</code> in <code>C:\Program Files\Git\cmd</code>, which is in my <code>Path</code> environment variable. The file contents looks like this:</p> <pre> #!/bin/sh # diff is called by git with 7 parameters: # path old-file old-hex old-mode new-file new-hex new-mode <b>"C:/Program Files/SourceGear/DiffMerge/DiffMerge.exe" "$2" "$5" \| cat</b> #"C:/Program Files/WinMerge/WinMergeU.exe" "$2" "$5" \| cat #"C:/Program Files/KDiff3/kdiff3.exe" "$2" "$5" \| cat </pre> <p>The basic format of this is stolen directly from <a href="">this post</a> on the Msysgit site. Provided your diff tool can be called from the command line, you'll be able to set it up to work with Git using this template. In this case I've used it to setup a call to <a href="">Sourcefear's DiffMerge</a>, a nice free (as in beer) diff and merge tool. </p> <p>You'll also see I've commented out calls to <a href="">WinMerge</a> and <a href="">KDiff3</a>, which are both free as in beer and speech. I ended up settling on DiffMerge because it is purdy (unlike KDiff3 -- sorry), and also does 3-way merges (unlike WinMerge, which was my previous diff tool of choice).</p> <p>The next step is telling Git about your wrapper. In your home directory (<code>C:\Users\(username)</code> or the corresponding Documents and Settings equivalent) Git will normally have created a <code>.gitconfig</code> file. If not then go ahead and create one. You'll need to have the following section in there:</p> <pre> [diff] external = C:/Program Files/git/cmd/git-diff-wrapper.sh </pre> <p>We can now use <code>git diff</code> and it will fire up our diff tool of choice.</p> <h2>Setting up a merge tool</h2> <p>I had more trouble getting a merge tool working, largely because putting references to paths like <code>C:/Program Files/...</code> in <code>.gitconfig</code> seems to bork when used here. Again I ended up using the wrapper approach, creating <code>git-merge-diffmerge-wrapper.sh</code> at <code>C:\Program Files\Git\cmd</code> to call DiffMerge. This file ended up looking like this:</p> <pre> #!/bin/sh # Passing the following parameters to mergetool: # local base remote merge_result "C:/Program Files/SourceGear/DiffMerge/DiffMerge.exe" "$1" "$2" "$3" --Alexander Groß's post on getting DiffMerge running on Cygwin-based Git</a> (with slight modifications, any faults are mine :)). We can then wire this up in <code>.gitconfig</code> again:</p> </pre> <p>Now remember that <code>C:\Program Files\Git\cmd</code> is on my <code>PATH</code>, so I can set the command to call <code>git-merge-diffmerge-wrapper.sh</code> without fully qualifying the path. The details on the arguments are available from the <a href="">git-mergetool(1) man page</a>. I've also left in a KDiff3 version that seems to work too (Git has some built in support for KDiff3 I think, which is why you can get away with only specifying the path).</p> <h2>Time for a test drive</h2> <p <code>cmd.exe</code> command line).</p> <pre>. </pre> <div class="note">Because I've used <code>echo</code> to stream data into <code>hello.txt</code> the files have ended up in binary mode. Let's ignore that as it is just to get an easy demo going. The important thing is we now have a merge conflict to resolve.</div> <p>If we now type in <code>git mergetool</code> Git ask's us if we'd like to run our merge tool. We can hit enter and up pops DiffMerge. If you wanted KDiff3, we could have called <code>git mergetool -t kdiff3</code>, or any other merge tool in our <code>.gitconfig</code> (by default the tool specified in the <code>merge.tool</code> config option is used).</p> <pre> PS> git mergetool Merging the files: hello.txt Normal merge conflict for 'hello.txt': {local}: modified {remote}: modified Hit return to start merge resolution tool (diffmerge): </pre> <div class="separator" style="clear: both; text-align: center;"> <a href=""><img src="" /></a></div> <p>Resolve the merge conflict however you like and then try this:</p> <pre> PS> echo Wow, it worked! > hello.txt PS> git diff </pre> <div class="separator" style="clear: both; text-align: center;"> <a href=""><img src="" /></a> </div> <p>Hooray, we have our diff tool working! We can also run commands like <code>git diff HEAD~ HEAD</code> and <code>git diff helloGit master</code> and get the output via our diff tool.</p> <h2>Conclusion</h2> <p>This setup earns the coveted <a href="">Works on My Machine</a> certification, but even if that's the only place it works then hopefully it still gives you enough information to configure your Windows diff and merge tools for use with Git.</p> <div class="separator" style="clear: both; text-align: center;"> <a href="" style="margin-left: 1em; margin-right: 1em;"><img src="" /></a></div> <p>If you hunt down the relevant command line options you should be able to get pretty much any tool working: <a href="">Beyond Compare</a>, <a href="">p4merge</a>, <a href="">TortoiseMerge</a> etc.</p> <p introduction to the SOLID principles of OO design<p>I would be very hard pressed to go passed Robert "Uncle Bob" Martin's <a href="">SOLID principles</a> as the single most useful tool for helping me with OO design. Some people seem to have a natural talent for OO design and thinking, and have an innate understanding of these principles without requiring the SOLID formalism. I, on the other hand, find them indispensable.</p> <p>Unfortunately the names used in the somewhat-cryptic "acronym of acronyms"[1] don't exactly lend themselves to being easily learned (Bob Martin and Scott discussed how this came about on a <a href="">Hanselminutes episode on SOLID</a>, which is well worth a listen). I thought I'd post my interpretation of the principles as a refresher for myself, and as an introduction for anyone trying the learn the terminology.</p> <p>I should point out I am far from a guru on this stuff, so if there's any misinformation in here please point it out in a comment or email, so I can correct the post and learn me some OO :).</p> <h2>Single Responsibility Principle</h2> <blockquote> <p><i>"There should never be more than one reason for a class to change." — Robert Martin, SRP paper linked from <a href="">The Principles of OOD</a></i></p> <p>My translation: A class should concentrate on doing one thing</p> </blockquote> <p>The SRP says a class should focus on doing one thing, or have one <i>responsibility</i>. This doesn't mean it should only have one method, but instead all the methods should relate to a single purpose (i.e. should be cohesive).</p> <p>For example, an <code>Invoice</code> class might have the responsibility of calculating various amounts based on it's data. In that case it probably shouldn't know about how to retrieve this data from a database, or how to format an invoice for print or display.</p> <p).</p> <p>Violations of the SRP are pretty easy to notice: the class seems to be doing too much, is too big and too complicated. The easiest way to fix this is to split the class.</p> <p".</p> <h2>Open Closed Principle</h2> <blockquote> <p><i>"Software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification." — Robert Martin paraphrasing Bertrand Meyer, OCP paper linked from <a href="">The Principles of OOD</a></i></p> <p>My translation: Change a class' behaviour using inheritance and composition</p> </blockquote> <p>Bob Martin's initial paper on the OCP linked from <a href="">The Principles of OOD</a> attributes the idea to Bertrand Meyer, who wrote that classes should be "open for extension, but closed for modification"[2]. The idea is that we can use OO techniques like inheritance and composition to change (or <i>extend</i>) the behaviour of a class, without modifying the class itself.</p> <p>Say we have an <code>OrderValidation</code> class with one big <code>Validate(Order order)</code> method that contains all rules required to validate an order. If the rules change, we need to change or <code>OrderValidation</code> class, so we are violating the OCP. If the <code>OrderValidation</code> contained a collection of <code>IValidationRule</code> objects that contained the rules, then we could write <code>Validate(Order order)</code> to iterate through those to validate the order. Now if the rules change then we can just create a new <code>IValidationRule</code> and add it to an <code>OrderValidation</code> instance at run time (rather than to the class definition itself).</p> <p.</p> <p <a href="">healthy dose of polymorphism</a> is generally the best treatment. :) I generally think of the OCP as an advertisement for the <i>Template Method</i> and <i>Strategy</i> design patterns.</p> <h2>Liskov Substitution Principle</h2> <blockquote> <p><i>"Functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it." — Robert Martin, LSP paper linked from <a href="">The Principles of OOD</a><br/></i></p> <p>My translation: Subclasses should behave nicely when used in place of their base class</p> </blockquote> <p>The LSP sounds deceptively straightforward — we should be able to substitute an instance of a subclass for its parent class and everything should continue to work. Easy right? Well, actually, no it's not, which is probably why we are often advised to <a href="">favour composition over inheritance</a>. Ensuring a base class works in any situation the parent does is really hard work, and whenever you use inheritance its a good idea to keep the LSP firmly in mind.</p> <p>The canonical example of an LSP violation (in fact, the one used in the <a href="">Hanselminutes episode on SOLID</a> mentioned earlier) is the <code>Square</code> IS-A <code>Rectangle</code> relationship. Mathematically a square is a special case of a rectangle with all sides of equal length, but this breaks the LSP when modelled in code. What should <code>SetWidth(int width)</code> do when called on a <code>Square</code>? Should it set the height as well? What if you have a reference to it via its base class, <code>Rectangle</code>? If you have code that expects one behaviour but gets another depending on which subtype it has, you can wind up with some very hard to find bugs.</p> <p>LSP violations can be easy to miss until you actually hit the condition where your inheritance hierarchy breaks down (I mean, a <a href="">square IS-A rectangle</a>, right?). The best way to reduce violations is to keep very aware of the LSP whenever using inheritance, including considering avoiding the problem using composition where appropriate.</p> <h2>Interface Segregation Principle</h2> <blockquote> <p><i>"Clients should not be forced to depend upon interfaces that they do not use." — Robert Martin, ISP paper linked from <a href="">The Principles of OOD</a></i></p> <p>My translation: Keep interfaces small and cohesive</p> </blockquote> <p>The ISP is about keeping interfaces (both <code>interface</code>, and <code>abstract class</code>).</p> <p>The first time I recognised a violation of the ISP was writing a minimal implementation of an ASP.NET <code><a href="">RoleProvider</a></code>, which required an implementation of the following methods:</p> <pre>) { ... } } </pre> <p>In my case I just wanted to use ASP.NET's built in facility for securing pages by role in the <code>web.config</code>, which means I needed to implement <code>GetRolesForUser(...)</code> and <code>Initialize(...)</code>. Can you guess what the other implementations were? That's right, <code>throw new NotImplementedException();</code>. This is very bad — if we have a <code>RoleProvider</code> instance we have no idea what sub-features it will support. On top of that we also have a lot of useless noise in our class. (If you like the <code>RoleProvider</code>, you might also enjoy the <code><a href="">MembershipProvider</a></code>.)</p> <p>The way to fix violations like this is to break down interfaces along the lines of responsibilities and apply the SRP. For the <code>RoleProvider</code> case, even if we just split it into <code>IRolesForUserLookup</code> and <code>IRoleManagement</code> (yuk), that would let us only implement what we need. If we need all the features then we can implement both interfaces, but we should not be forcing clients to fake or throw in implementations that are meaningless to them.</p> <h2>Dependency Inversion Principle</h2> <blockquote> <p><i>"A. High level modules should not depend upon low level modules. Both should depend upon abstractions.<br/> B. Abstractions should not depend upon details. Details should depend upon abstractions." — Robert Martin, DIP paper linked from <a href="">The Principles of OOD</a></i></p> <p>My translation: Use lots of interfaces and abstractions</p> </blockquote> .</p> <p>At its simplest, this can just be the difference between referencing an <code>EmployeeFinder</code> class or an <code>IEmployeeFinder</code> interface. The concrete <code>EmployeeFinder</code> class can access a database or a file, but the client class only cares that it meets the <code>IEmployeeFinder</code> contract. Better yet, our client class doesn't have to be tied in any way to the <code>EmployeeFinder</code> class. It could instead use <code>SqlEmployeeFinder</code>, <code>XmlEmployeeFinder</code>, <code>WebServiceEmployeeFinder</code> or <code>MockEmployeeFinder</code>.</p> <p>Where the DIP starts to become really useful and a bit more profound is in a related concept, <i>Dependency Injection</i>. Dependency Injection is about getting other code to insert the actual dependency instances into our class, so we don't even have the client class <code>new</code>ing up any of the concrete instances. This completely isolates our class and makes change and reuse much easier. (I've covered some introductory stuff in a <a href="">previous ramble on dependency injection</a>).</p> <p, <a href="">onions</a> and <a href="">hexagons</a> these days, so I tend to think about the DIP entirely from the point of view of abstracting dependencies.</p> <h2>SOLID principles as a whole</h2> <p'm.</p> <p.</p> <p>This is what people mean when they say that TDD and "testability" is not about testing, it is about design. Scott Bellware recently published a good post on <a href="">design, SOLID and testability</a> that goes into this in more detail.</p> <h2>Conclusion</h2> <p>This has been a quick introduction to the SOLID principles. Hopefully it will make it easier for people to jump into the <a href="">gory details of all the principles</a>. Even if you have an innate grasp on these principles, I think it is worth going to the trouble to learn them, if only to help get a common language with which to discuss these principles.</p> <h2>Recommended reading and listening</h2> <ul> <li>Robert Martin's original SOLID papers from <a href="">The Principles of OOD</a></li> <li><a href="">Hanselminutes episode on SOLID</a></li> <li>Scott Bellware's post on <a href="">Good Design is Easily-Learned</a></li> <li>Laila Bougria's post on <a href="">Design Principles</a>, including SOLID</li> </ul> <h2>References</h2> <p> [1] Yammer exchange with <a href="">Xerxes</a> <br/> [2] Bertrand Meyer, <a href="">Object-Oriented Software Construction</a> <br/> [3] Gene Shadrin, <a href="">Three Sources of a Solid Object-Oriented Design</a>, SYS-CON Media 2nd Blogoversary<p>In a couple of days I will have been <a href="">blogging for two years</a>. Please excuse a little self-indulgence on my part while I go through the usual blogoversary formalities.</p> <h2>Some random statistics</h2> <p>Most of this is from Google Analytics, which should be a semi-decent approximation to reality.</p> <ul> <li>264 posts</li> <li>Around 130 valued feed subscribers (including some which aren't just me subscibing from different PCs). :)</li> <li>Over 30,000 visits and over 40,000 page views since August 2007. Most recently there's been about 3,000 visits a month. Not a huge amount, but probably more than this little blog warrants. :)</li> <li>Busiest day: 768 visits on 3rd April 2008, thanks to a <a href="">Reddited Python post</a>. <li>Browser usage: Firefox 50%, IE 42%, Opera, Chrome and Safari around 2% each.</li> <li>OS usage: Windows 92%, Mac 4%, Linux ~4%</li> <li>17 visits from iPhones. Apparently one from an HPUX :)</li> <li>262 visits from Microsoft.</li> <li>Visits from 141 countries, with most from US, UK, India, Australia and Canada. Slightly less visits from Gibraltar, Maldives, Liechtenstein, and Madagascar :)</li> <li>Search engine stats: Google 99.36%. Yahoo came second. I'm guessing Blogger.com bias. :)</li> </ul> <h2>Most visited posts</h2> <p>The Python and ORM posts were due to unsolicited Redditing and DotNetKicking. The others care of Google.</p> <ul> <li><a href="">99 problems with Python (1-10)</a></li> <li><a href="">Confirm delete for GridView's CommandField using JavaScript</a></li> <li><a href="">Viewing the SQL generated by NHibernate</a></li> <li><a href="">Messing around with various ORMs (series)</a></li> </ul> <h2>Posts I like but no one visited :)</h2> <p>Proving once and for all that just because you build it doesn't mean that they will come.</p> <ul> <li><a href="">Explaining good code to non-geeks</a>. After reading this interested family members started to grok what I do for a living :)</li> <li><a href="">Implementing Python-like Range in C#</a></li> <li><a href="">Fluently constructing test objects</a></li> <li><a href="">BDD test naming with AutoHotKey</a>. Picked up by the legendary <a href="">JP Boodhoo</a>. Yes, I'm blushing :)</li> <li><a href="">Yet another way of raising events from mocks</a>, which ended up getting into Rhino Mocks 3.5.</li> <li><a href="">NHibernate mappings using xml, attributes, and Fluent NHibernate</a></li> <li><a href="">Attempting to understand dependency injection</a></li> <li><a href="">An assortment of basic TDD tips</a></li> <li><a href="">Getting to grips with ReSharper</a>. Bit old but still reasonably relevant.</li> <li><a href="">Learning C# lambda syntax from delegates</a></li> </ul> <h2>Where to from here?</h2> <p>The purpose of my blog remains the <a href="">same as last year</a>: a way of helping me learn stuff. I still find blogging to be one of the best ways for me to solidify a concept in my mind.</p> <p>I've found with my new job (~5 months) I've been doing tonnes of coding in an Agile, TDD-toting team, and so a lot of my time and learning goes on there. My work also has an enormous library of text books which I've been working through, and I'm also tending (with the exception of this post :)) to be a bit more selective about what I post, so a lot of my Frankenstein-like learning experiments never see the light of a browser. All this has made my blog a bit quieter of late, but hopefully this has meant a higher signal-to-noise ratio over the last couple of months.</p> <p>Thanks to everyone that's subscribed, commented, or visited my little patch of the intraweb -- it's great to think that my ramblings occasionally help on 64-bit OS<p>I got the following exception when running the unit tests as part of a local build of our .NET project today:</p> <pre>System.BadImageFormatException : Could not load file or assembly '<i>(assembly name)</i>' or one of its dependencies. An attempt was made to load a program with an incorrect format.</pre> <p>This seemed a bit odd, because the build was working on every other machine. Even odder, the build and tests ran fine within Visual Studio.</p> <p <a href="">WoW64</a>.</p> <p").</p> <p>Hope this saves someone some hair-tearing. :)</p> <p><b>Update:</b> I have found the <a href="">Corflags</a> tool invaluable for flagging a DLL as needing to run under the 32 bit CLR. This is useful when you don't have the source to recompile the app, and has been put to good use getting the old, free version of <a href="">NCover to run on a 64-bit bit OS</a>. A good write up on Corflags is <a href="">here</a>.</p> <p><b>References:</b> <ul> <li><a href="">MSDN thread on this error with an EF pre-release</a></li> </ul> to get commit message for JIRA integration<p>At my work we use JIRA for issue tracking, and the <a href="">FishEye</a> plugin to integrate with our source control system. This means that for each commit against an issue we need to start our commit message with details of the issue so that JIRA/FishEye can pick it up. For example:</p> <pre>DAVE-1234 (Pairing with Dave is annoying) Updated code to crash while Dave is around, so pairing can finish. </pre> <p. :)</p> <p>The title of the JIRA page for an issue has all the information we need:</p> <pre>[#DAVE-1234] Pairing with Dave is annoying - Your JIRA Instance Name</pre> <p>You can hackily parse this using javascript:</p> <pre> + ")"); </pre> <p>If you prefix that with <code>javascript:</code>. :)</p> <p>FireFox reformats the bookmark location automatically, but here is what you end up with for completeness' sake:</p> <pre>")"); </pre> <p <a href="">works on my machine</a> -- hope it works on yours too! :)< formatting with test-first extension method abuse<p>My pair and I were looking at performing some unusual string formatting today. We kept finding that the extension methods in <code>System.Linq.Enumerable</code> were pretty helpful, but they often seemed to <a href="">fall just short</a> of what we needed to make the code really readable. Once I got home I thought I'd see how far I'd get by dumping some functionality into extension methods with blatant disregard for the potential consequences. (Unfortunately I had to miss the <a href="">Sydney ALT.NET</a> meeting tonight, so I had a bit of time to play around.)</p> <h2>Formatting arrays for acceptance tests</h2> <p>Here is the basic behaviour we're after. Given an array or other enumerable of integers (or of any type with a sensible <code>ToString()</code> method really), we want to return the items as a single, comma separated string. The strange part of it is that if every value in the enumeration is the same, we just want to return that one value as a single string. The reason for this unusual behaviour is to help get some easily usable output for the acceptance test framework we are using.</p> <p>As this is just a helper for acceptance tests (i.e. we won't be polluting namespaces in production code) I'll dump this functionality onto any <code>IEnumerable<T></code> using an extension method. </p> <h2>Starting test first</h2> <p>Let's start with an easy case: what should happen when we have an empty enumerable?</p> <pre> [TestFixture] public class FixtureFormatterTests { [Test] public void Empty_array_should_format_as_empty_string() { var emptyArray = new int[0]; Assert.That(emptyArray.ToFixtureString(), Is.EqualTo(string.Empty)); } } public static class HelperExtensions { public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { return string.Empty; } } </pre> <p>After that monumentally brilliant piece of code, let's add the comma-separated string part of the requirement.</p> <pre> [Test] public void Array_with_different_values_should_give_comma_separated_string() { var ints = new[] {1, 2, 3, 4}; Assert.That(ints.ToFixtureString(), Is.EqualTo("1,2,3,4")); } </pre> <p>Now we'll get it to pass. We'll lean heavily on the built-in <code><a href="">String.Join(String, String[])</a></code> method to do the work for us.</p> <pre> public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { if (enumerable.Count() == 0) return string.Empty; return string.Join(",", enumerable.Select(item => item.ToString()).ToArray()); } </pre> <p>This passes, but it's a bit ugly. Let's look at refactoring.</p> <h2>First refactoring</h2> <p>First, I've got a feeling that if our enumerable is empty, <code>String.Join(...)</code> won't concatenate anything, and so will just return an empty string. This would render our first line redundant.</p> <pre>public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { return string.Join(",", enumerable.Select(item => item.ToString()).ToArray()); }</pre> <p>It still passes both our tests so we are safe (I love unit tests :)). We also have that ugly bit of code where we are translating our <code>IEnumerable<T></code> into an array of strings, using the <code>Select()</code> extension method. As I'm keen to start over using extensions methods, let's hide all that away in a Python-like <code>join()</code> method. Python's <code>join()</code> works like this:</p> <pre> >>> ints = [1,2,3,4] >>> ",".join(str(i) for i in ints) '1,2,3,4' </pre> <p>I'd like to do that, but abstract away the sequence/enumerable to string conversion. Let's do this using an extension method to <code>char</code>:</p> <pre> public static string Join<T>(this char separator, IEnumerable<T> enumerable) { return string.Join(separator.ToString(), enumerable.Select(item => item.ToString()).ToArray()); } public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { <b>return ','.Join(enumerable);</b> } </pre> <p>Assuming you know the whole "Join" concept, our <code>ToFixtureString()</code> method is now pretty darned clean :). The original ugliness is now moved to the <code>Join()</code> method, but at least it is all directly related to the purpose of that method. In its original spot I think it obscured the intention behind the <code>ToFixtureString()</code> method.</p> <h2>Completing our <code>ToFixtureString()</code> requirements</h2> <p>The last requirement we have for this is to only show one value if all the items in the enumerable are the same.</p> <pre> [Test] public void Array_with_the_same_values_should_return_that_value_as_a_single_string() { const int value = 2; var ints = new[] {value, value, value}; Assert.That(ints.ToFixtureString(), Is.EqualTo(value.ToString())); } </pre> <p>Here's an attempt at get this to pass.</p> <pre> public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { <b>var firstItem = enumerable.First(); if (enumerable.All(item => item.Equals(firstItem))) { return firstItem.ToString(); }</b> return ','.Join(enumerable); } </pre> <p>This fails our <code>Empty_array_should_format_as_empty_string</code> test because the <code>enumerable.First()</code> call throws with <code>InvalidOperationException: Sequence contains no elements</code>. So we're back to that <code>enumerable.Count() == 0</code> line, which gets all our tests passing again.</p> <pre> public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { <b>if (enumerable.Count() == 0) return string.Empty;</b> var firstItem = enumerable.First(); if (enumerable.All(item => item.Equals(firstItem))) { return firstItem.ToString(); } return ','.Join(enumerable); } </pre> <h2>Refactoring out the empty enumerable check</h2> <p>I don't like <code>enumerable.Count()</code>. It needs to go through the entire enumerator to get the count, when we really only care if the enumerable is empty. Sounds like time for some more extension method abuse. Here's some tests that require adding an <code>IsEmpty()</code> extension method to <code>IEnumerable<T></code>:</p> <pre> [TestFixture] public class IsEmptyEnumerableTests { [Test] public void Empty_enumerable() { Assert.That(new int[0].IsEmpty()); } [Test] public void Non_empty_enumerable() { Assert.That(new[]{1,2,3}.IsEmpty(), Is.False); } } public static class HelperExtensions { //... <b>public static bool IsEmpty<T>(this IEnumerable<T> enumerable) { return !enumerable.GetEnumerator().MoveNext(); }</b> } </pre> <p>This is a bit hacky, but means we only need to to see if our enumerator has a single item to determine whether it is empty, and we can make our <code>ToFixtureString()</code> method a bit more expressive as a result:</p> <pre> public static string ToFixtureString<T>(this IEnumerable<T> enumerable) { <b>if (enumerable.IsEmpty()) return string.Empty;</b> var firstItem = enumerable.First(); if (enumerable.All(item => item.Equals(firstItem))) { return firstItem.ToString(); } return ','.Join(enumerable); } </pre> <h2>Vague semblance of a conclusion</h2> <p>We now have our unusual formatting covered, and <code>IsEmpty()</code> and <code>Join()</code> extension methods to help make our code a bit cleaner. I'm not advocating this kind of thing for every day use, but I think it shows how useful extension methods can be to make your code more expressive. It comes at the cost of changing classes that most .NET developers are familiar with, so it's definitely something to be careful C# lambda syntax from delegates<p>As a sweeping generalisation, I've found that developers who are really proficient with delegates / anonymous delegates seem to have a bit of an adverse reaction to seeing the <a href="">lambda syntax in C# .NET 3.5</a>. Luckily I'm proficient with very little, so the transition was easy for me :). This is a post to try and make the transition easier for people more competent than me :).</p> <h2>From delegates to lambdas</h2> <p>Say I have a <code>Widget</code> class, which just contains a <code>Name</code> and a <code>WeightInGrams</code>.</p> <pre> public class Widget { public Widget(string name, int weightInGrams) { Name = name; WeightInGrams = weightInGrams; } public string Name { get; set; } public int WeightInGrams { get; set; } } }</pre> <p>Now we want to search through an array of these and find how many are under 300 grams. Why? Er, why not? We'll use <code>Array.FindAll</code> to do this old skool (as opposed to fancy LINQy stuff like using <code>Where()</code>). <code>FindAll</code> takes an array of type <code>T</code> and a <code>Predicate<T></code>, which is a delegate that takes a <code>T</code> and returns a <code>bool</code> indicating whether the predicate has been matched.</p> <pre> [TestFixture] public class LambdaTests { [Test] public void SearchArrayUsingDelegate() { var widgets = SixWidgetsFrom100GramsTo600Grams(); var widgets300GramsOrLess = Array.FindAll(widgets, <b>Weighs300GramsOrLess</b>); Assert.That(widgets300GramsOrLess.Length, Is.EqualTo(NumberOfWidgets300GramsOrLess)); } <b>private bool Weighs300GramsOrLess(Widget widget) { return widget.WeightInGrams <= 300; }</b> private const int NumberOfWidgets300GramsOrLess = 3; static Widget[] SixWidgetsFrom100GramsTo600Grams() { return new[] { new Widget("W1", 100), new Widget("W2", 200), new Widget("W3", 300), new Widget("W4", 400), new Widget("W5", 500), new Widget("W6", 600) }; } } </pre> <p>As of .NET 2.0 we can use an anonymous delegate to do this inline:</p> <pre> [Test] public void SearchArrayUsingAnonymousDelegate() { var widgets = SixWidgetsFrom100GramsTo600Grams(); var widgets300GramsOrLess = Array.FindAll(widgets, <b>delegate(Widget widget) { return widget.WeightInGrams <= 300; }</b>); Assert.That(widgets300GramsOrLess.Length, Is.EqualTo(NumberOfWidgets300GramsOrLess)); } </pre> <p>As of .NET 3.5 we have lambda syntax, which provides a terser way of expressing our predicate function:</p> <pre> [Test] public void SearchArrayUsingLambda() { var widgets = SixWidgetsFrom100GramsTo600Grams(); var widgets300GramsOrLess = Array.FindAll(widgets, <b>widget => widget.WeightInGrams <= 300</b>); Assert.That(widgets300GramsOrLess.Length, Is.EqualTo(NumberOfWidgets300GramsOrLess)); } </pre> <p>Clear as mud? Let's have a closer look at how we convert from delegate to a lambda expression.</p> <pre> //Original delegate: delegate(Widget widget) { return widget.WeightInGrams <= 300; } //Drop the "delegate" keyword, and add a funky "=>" operator, which goes by all sorts of creative names :) (Widget widget) => { return widget.WeightInGrams <= 300; } //The C# 3.0 compiler has type inference, so we can also drop the argument type and let the compiler figure it out. //If we have a single statement to the right of the "=>" operator, this will be returned from the function, //so we can also drop the braces, end-of-statement semicolon and the explicit return. widget => widget.WeightInGrams <= 300 </pre> <p>So what's the difference between our anonymous delegate and our lambda expression? In this example, absolutely nothing other than a terser (and somewhat addictive IMO) syntax. Let's compare the generated code for both just to prove this:</p> <pre> [CompilerGenerated] private static bool <SearchArrayUsingAnonymousDelegate>b__0(Widget widget) { return (widget.WeightInGrams <= 300); } [CompilerGenerated] private static bool <SearchArrayUsingLambda>b__2(Widget widget) { return (widget.WeightInGrams <= 300); } </pre> <p>So based on this example anonymous delegates and lambdas are exactly the same, it's just a matter of getting used to writing a bit less noise code. :)</p> <h2>Exactly the same, except when they're different...</h2> <p>Of course there's a catch. Actually, I can think of two, and they both relate to <a href="">expression trees</a>. To support a lot of LINQ magic, lambda expressions can be converted to expression trees at compile time. An expression tree is basically just a bunch of objects representing each part of the lambda expression. A query provider, like the one provided by LINQ to SQL, can then process the expression tree and execute the expression in a different way, say, by converting it to TSQL and running it against database.</p> <p>To get the compiler to generate an expression tree from a lambda expression we just need to specify the type differently:</p> <pre> Predicate<Widget> lambda = widget => widget.WeightInGrams <= 300; Expression<Predicate<Widget>> expressionTree = widget => widget.WeightInGrams <= 300; </pre> <p>So how does this relate to differentiating anonymous delegates and lambdas?</p> <pre> //Compiles fine: Expression<Predicate<Widget>> expressionTree = <b>widget => widget.WeightInGrams <= 300</b>; //WON'T COMPILE: Expression<Predicate<Widget>> expressionTree = <b>delegate(Widget widget) { return widget.WeightInGrams <= 300; }</b>; <b>/* error CS1946: An anonymous method expression cannot be converted to an expression tree /</b> </pre> <p>As you can see from the code sample above, the compiler will simply refuse to convert the delegate form to an expression tree. So the way the compiler handles the two are quite different as soon as you introduce expression trees. I also mentioned a second catch. Take a look at this modification of the previous example:</p> <pre> //WON'T COMPILE: Expression<Predicate<Widget>> expressionTree = <b>widget => { return widget.WeightInGrams <= 300; }</b>; <b>/ error CS0834: A lambda expression with a statement body cannot be converted to an expression tree /</b> </pre> <p>This second catch is that there is actually a <a href="">difference between lambda <b>expressions</b> and lambda <b>statements</b></a>. A lambda statement contains braces and a function body, and can potentially have multiple lines like a standard delegate. A lambda expression is the single line with an implicit return. So in our original, Array-searching example, the following two statements are actually are different if you are trying to assign them to expression trees.</p> <pre> //Lambda statement widget => { return widget.WeightInGrams <= 300; } //Lambda expression widget => widget.WeightInGrams <= 300 </pre> <div class="note"> <p><b>Aside:</b> In case you were wondering, here is the expression tree generated by the compiler for the <code>widget => widget.WeightInGrams <= 300</code> lambda expression, care of Reflector:</p> <pre> ParameterExpression CS$0$0000; Expression<Predicate<Widget>> expressionTree = Expression.Lambda<Predicate<Widget>>( Expression.LessThanOrEqual( Expression.Property( CS$0$0000 = Expression.Parameter(typeof(Widget), "widget"), (MethodInfo) methodof(Widget.get_WeightInGrams)), Expression.Constant(300, typeof(int))), new ParameterExpression[] { CS$0$0000 } ); </pre> </div> <h2>Conclusion</h2> <p>So in conclusion, lambdas are simply, for most intents and purposes, a neater syntax for defining delegates.</p> <pre> //Delegate: delegate(Widget widget) { return widget.WeightInGrams <= 300; } //Drop the delegate and add the "=>" operator to get a lambda statement (Widget widget) => { return widget.WeightInGrams <= 300; } //Use type inference and implicit return to get a lambda expression widget => widget.WeightInGrams <= 300 </pre> <p>The only differences that can bite you are when you are dealing with expression trees, either explicitly via the <code>Expression<></code> type, or implicitly by using the LINQ operators. Hope this helps, or at least has caused no significant damage to your understanding of lambd (very) basics of AAA with Rhino Mocks 3.5<p>A small contingent from my work made the trek out to the first <a href="">Sydney ALT.NET</a> meeting last night. It was great to be in a room full of people all intent on finding better ways to develop software. Afterward I was dragged kicking and screaming (<code></sarcasm></code> :)) by my colleagues to a local pub for debriefing over beers and a laptop. One topic discussed was the Arrange, Act, Assert (AAA) style of mocking using <a href="">Rhino Mocks 3.5</a>.</p> <p.</p> <h2>Record / Replay semantics</h2> <p>The traditional way of mocking has been to use record/replay. This means you <i>record</i> a number of expectations against a mock object, then change the mock to <i>replay</i> mode and exercise the subject under test (SUT). In replay mode, the mock will throw an exception if an unexpected method is called (for strict mocks). The final step is to <i>verify</i> the expectations you recorded, which will throw an exception if one of the expected methods was not called.</p> <p>Let's have a look at one of my dodgy-as-usual examples (probably even worse than normal, as it was written in a pub around 11 pm after a long day :))</p> <pre> public interface IEmailService { void Send(MailMessage msg); } public class InvoiceSender { private readonly IEmailService emailService; public InvoiceSender(IEmailService emailService) { this.emailService = emailService; } <b>public void SendInvoice(float amount, string to) { var msg = new MailMessage("me@me.com", to, "Invoice", string.Format("Please pay {0}", amount)); emailService.Send(msg); }</b> } </pre> <p>Our subject under test is <code>InvoiceSender</code>, and we want to verify that the <code>IEmailService.Send(MailMessage)</code> method is being called from <code>SendInvoice(float, string)</code>.</p> <pre> , "me@me.com"); //Verify expectations mockRepo.VerifyAll(); } </pre> <p>Here we've used Rhino Mocks to generate a mock implementation of the <code>IEmailService</code> interface. We have recorded a single expectation against it: it is expecting to have its <code>Send(...)</code> method called with any argument (hence the <code>IgnoreArguments()</code> call -- for non-pub code we would probably want to check the argument).</p> <p>We then use <code>ReplayAll()</code> to switch to replay mode, which tells our mocks that we have finished recording expectations and are ready to see what is really called on our mock. We then exercise the SUT, and verify that our expectations were met (i.e. <code>Send()</code> was called on our mock). The test passes -- victory is ours!</p> <h2>Writing the test using AAA</h2> <p>There's nothing really wrong with the record/replay approach. If you like it that's great! Some people find it confusing (or at least <a href="">unnatural</a>), probably because it doesn't quite fit the <a href="">four phase test</a> structure used for state-based testing (Setup, Exercise, Verify, Teardown).</p> <p>The AAA approach lets us use a more state-based testing approach with our mocks. Let's rewrite our previous test using AAA:</p> <pre> , "me@me.com"); //Assert mockEmail.AssertWasCalled(service => service.Send(Arg<MailMessage>.Is.Anything)); } </pre> <p>Here we are creating our mock using the new static <code>GenerateMock<T>()</code> method introduced in Rhino Mocks 3.5. We then exercise the SUT with an identical line of code to the one used in the first test. Finally, we assert that the <code>Send()</code> method on our mock was called as we expected. The test passes -- again we are victorious!</p> <p.</p> <p>Under the hood Rhino Mocks is still going off and doing pretty much the same thing as its always done. The static <code>GenerateMock<T>()</code> method simply creates a dynamic mock already in <i>replay</i> mode. The mock remembers all calls against it, and we can then use <code>AssertWasCalled()</code> and other methods to check these calls and make sure the ones we want are there.</p> <div class="note"><b>Aside:</b> One of the issues raised during the Sydney ALT.NET meeting was <a href="">mocks vs. stubs</a>. I think AAA makes the distinction a bit more apparent. You'll tend to use a stub during the <i>Arrange</i> part of your test to provide indirect inputs to the SUT, whereas you will use mocks to verify behaviour and indirect outputs of the SUT during the <i>Assert</i> phase. From the <a href="">Rhino Mocks wiki page on 3.5</a> (<a href="">rev. 40</a>), "A stub will never cause a test to fail", whereas mocks will fail if the expectations on them aren't met.</div> <p>This is only a very simplistic example to illustrate the basic differences for each approach. For more realistic cases the benefits of AAA become more apparent (see <a href="">Jimmy Bogard's post on AAA with BDD tests</a> for a good example).</p> <p>These couple of lines of code are available from my Google Code repository if you want run the tests and have a bit of a play around: <a href="">DaveSquared.MockSample.zip< ALT.NET group<p>Just wanted to quickly pass on the <a href="">announcement</a> that a <a href="">Sydney ALT.NET group</a> is starting up. <a href="">First meeting</a> is at the Thoughtworks office in the city on 30th September.</p> <p>Hopefully this will do well -- I'd love a group in Sydney where we can focus on software development practices in .NET, with specific tools and technologies taking a bit of a back seat.< mappings using xml, attributes, and Fluent NHibernate<p>A <code>.hbm.xml</code>.</p> <p>That said, there are alternatives hand coding the <code>.hbm.xml</code> mapping files. I thought I'd cover a few of the options here: NHibernate Mapping Attributes, and Fluent NHibernate.</p> <h2>Getting started</h2> <p>I decided to reuse the extra-simple scenario from my <a href="">ORM roundup</a>:</p> <p><a href=""><img id="BLOGGER_PHOTO_ID_5145922358406504498" style="cursor: pointer" alt="" src="" border="0"></a></p> <p>Now let's create some POCOs for to model our suppliers and states. I've added these to an Entities folder in an otherwise blank C# Class Library project.</p> <pre> /; } } } } </pre> <p>These are nice ordinary classes, with no consideration given as to how they will be persisted. The only concession we have made is making everything <code>virtual</code> by default, so that it is easy for NHibernate to create proxies from these classes.</p> <p>I'll also throw in an App.config so NHibernate knows which database to talk to. This time around I'm using NHibernate 2.0, which has a <a href="">new configuration format</a> from the last time I looked at this example.</p> <h2>Hand coding Hibernate Mapping Files</h2> <p>Time to map our entity classes to our database. Let's start off with the standard, hand coded <code>.hbm.xml</code> approach. We'll create a <code>State.hbm.xml</code> file and a <code>Supplier.hbm.xml</code>).</p> <pre> <!--> </pre> <p <code>bag</code> collection). These files are explained in more detail in my <a href="">Messing around with NHibernate</a> post. </p> <h2>Testing our mappings</h2> <p.</p> <pre> public class NHibernateTests { protected static readonly ISessionFactory SessionFactory = getSessionFactory(); <b>private static ISessionFactory getSessionFactory() { Configuration config = new Configuration(); config.AddAssembly(Assembly.GetExecutingAssembly()); return config.BuildSessionFactory(); }</b> ); } } } </pre> <p>This code intialises a new <code>ISessionFactory</code> using the configuration settings in the <code>App.config</code>, and the <code>config.AddAssembly(Assembly.GetExecutingAssembly());</code> line adds the <code>.hbm.xml</code> mappings embedded in our DLL.</p> <p>I've also used the <code>Get_suppliers_servicing_NSW()</code>.</p> <h2>NHibernate Mapping Attributes</h2> <p><a href="">NHibernate Mapping Attributes</a> <code>Supplier</code> and <code>State</code> classes.</p> <pre> /; } } } </pre> <p>We no longer need our <code>.hbm.xml</code> files, and have instead translated the relevant mapping information to attributes on the classes themselves. By using attributes NHMA can infer some of the mapping information we previously had to enter explicitly (for example, <code><property name="Name" type="String" /></code> just becomes <code>[Property] public virtual String Name {...}</code>), and we have traded our angle brackets for square ones :). There are also a few strange things going on here. Look at this extract from Supplier.cs:</p> <pre> [Id(<b>0</b>,Fluent NHibernate< <code>.hbm.xml</code> <a href="">project's SVN repository</a>, so much of this will probably change before it hits version 1.0.</p> <p>I've reverted our <code>Supplier</code> and <code>State</code> classes back to Plain Old CLR Objects (removed all the NHMA attributes) and also taken out the <code>.hbm.xml</code> files. The first thing we need to do is create some Fluent Nhibernate <code>ClassMap</code> classes.</p> <pre>"); } } </pre> :</p> <pre> private static ISessionFactory getSessionFactory() { var config = new Configuration(); config.AddMappingsFromAssembly(Assembly.GetExecutingAssembly()); return config.BuildSessionFactory(); } </pre> <p>Looks pretty good to me. :) But it gets better -- say I always name my identifiers in the form <code><i>EntityName</i>Id</code>. If Fluent NHibernate knew that, then I could reduce my supplier class map to this:</p> <pre> public class SupplierMap : ClassMap<Supplier> { public SupplierMap() { Id(x => x.SupplierId); Map(x => x.Name); <b>HasManyToMany<State>(x => x.StatesServiced) .AsBag() .WithTableName("Supplier_StatesServiced");</b> } } </pre> <p>After all, we know the keys used to map suppliers and states are going to be <code>SupplierId</code> and <code>StateId</code>, so the many-to-many mapping becomes trivial. Fluent NHibernate currently assumes the names will in the form <code>supplier_id</code>, but that's no big deal, because it also let's me change the conventions used:</p> <pre> private static ISessionFactory getSessionFactory() { var config = new Configuration(); var model = <b>getFluentNhibernatePersistenceModel()</b>; model.Configure(config); return config.BuildSessionFactory(); } private static PersistenceModel getFluentNhibernatePersistenceModel() { var model = new PersistenceModel(); <b>model.Conventions.GetForeignKeyName = prop => prop.Name + "Id";</b> //By default assumes prop.Name + "_id" <b>model.Conventions.GetForeignKeyNameOfParent = type => type.Name + "Id";</b> model.addMappingsFromAssembly(Assembly.GetExecutingAssembly()); return model; } </pre> <p>Pretty neat, huh? You can imagine how trivial you could get the mappings if you set your conventions correctly.</p> <p>There is work under way to make this even easier using <a href="">AutoMap</a> functionality, which will be used to auto-magically infer mappings for your entities. You can then customise any special cases (like the many-to-many relationship we have in this case -- it will probably assume the more common one-to-many case by default).</p> <h2>Tools not covered here</h2> <p>I also had a quick look at <a href="">ActiveWriter</a>,.</p> </p> <p>There are a number of <a href="">other tools mentioned in the NHibernate 1.2 docs</a>, including <code>hbm2net</code> (generate classes from HBM), as well as generation tools like CodeSmith and MyGeneration, but most of these seem to focus on generating the C# classes or SQL scripts for creating the database schema from the <code>.hbm.xml</code>. I think I'd prefer to control my entity and database creation, and instead try and make the mapping itself easier.</p> <h2>Conclusion</h2> <p>Fluent NHibernate looks absolutely fantastic, but is still in very early stages of development. If you don't like living on the bleeding edge, then the standard <code>.hbm.xml</code> files really aren't that bad once you've set up a couple of them. The good thing is you can switch between all these mapping methods without changing anything but the <code>ISessionFactory</code> initialisation code, which only occurs in one place within your application. All these changes were made with a continuously green test both item and index during C# enumerations<p>I recently got an <a href="">interesting comment</a> on an older post of mine about implementing a <a href="">Python-like range() function in C#</a>. The commenter posed a solution to the slight feeling of disappointment experienced when you have a <code>foreach</code> loop and then realise you need to access the loop index, forcing a conversion to a <code>for</code> loop or manually incrementing a counter. The solution ended up with a syntax like this:</p> <pre> //From <a href="">this comment</a>: int[] a = new int[] { 1, 2, 3, 4, 5 }; foreach (int i in Range.Array(a)) { // do something with i or a[i] } </pre> <p>Great concept! :) Let's take it a step further by drawing some more inspiration from Python. Here's a Python list comprehension that uses the <code>enumerate()</code> function to loop over tuples of both index and item:</p> <pre> >>> sampleList = ['a','b','c','d'] >>> [(index,item) for index, item in enumerate(sampleList)] [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')] </pre> <p>Or in a more C#-like format:</p> <pre> >>> for index, value in enumerate(sampleList): print(index, value) (0, 'a') (1, 'b') (2, 'c') (3, 'd') </pre> <p>Let's see how this could work in C#. As usual, I'll start with a test:</p> <pre> [Fact] public void Can_enumerate_index_and_item() { String[] strings = {"a", "b", "c", "d"}; int expectedIndex = 0; <b>foreach (var tuple in Enumerate.Over(strings)) {</b> Assert.Equal(expectedIndex, tuple.Index); Assert.Equal(strings[tuple.Index], tuple.Item); expectedIndex++; } } </pre> <p>To pass this we'll need a simple <code>Tuple</code> class (<a href="">better versions available</a>) and an <code>Enumerate</code> class (not entirely happy with the names, but we're just mucking around here). I'm going to violate <a href="">YAGNI</a> guidelines here and not restrict us to just arrays of Strings.</p> <pre> public class Tuple<T> { public int Index { get; private set; } public T Item { get; private set; } public Tuple(int index, T item) { Index = index; Item = item; } } public class Enumerate { public static IEnumerable<Tuple<T>> Over<T>(IEnumerable<T> items) { int index = 0; foreach (T item in items) { yield return new Tuple<T>(index++, item); } } } </pre> <div class="note"><b>Note added 2008-10-03:</b> As a colleague of mine pointed out, this is a bit evil as it is implying <code>foreach</code> will return items in the same order as indexed. This isn't actually guaranteed at all, so you might get cases where the returned index isn't the actual index of an item.</div> <p>The original test passes (along with a couple of others omitted for brevity), and we can now write a C# version of the Python <code>enumerate()</code> sample at the start of this post:</p> <pre> String[] strings = { "a", "b", "c", "d" }; foreach (var tuple in Enumerate.Over(strings)) { Console.WriteLine(tuple.Index + ", " + tuple.Item); } / Outputs: 0, a 1, b 2, c 3, d */ </pre> <p>I'm fairly sure there's a better (LINQ-y?) way of doing this, but this is all my Googling and I can come up with right the SQL generated by NHibernate<p>Is it possible to modify the SQL generated by NHibernate? Yes:</p> <pre>public class BadInterceptor : EmptyInterceptor, IInterceptor { SqlString IInterceptor.<b>OnPrepareStatement(SqlString sql)</b> { return doHorribleThingsToSqlString(sql); } private SqlString doHorribleThingsToSqlString(SqlString sql) { ... } } protected static readonly ISessionFactory SessionFactory = initialiseSessionFactory(); private static ISessionFactory initialiseSessionFactory() { var config = new Configuration(); config.AddAssembly(Assembly.GetExecutingAssembly()); <b>config.SetInterceptor(new BadInterceptor())</b>; return config.BuildSessionFactory(); } </pre> <p>Now don't! :) Seriously, it's evil.</p> <p>If anyone knows a nice way to get NHibernate to add some custom SQL as part of it's SQL generation process, rather than this brute-force approach, then please let me know. I was initially playing around with this code to add some calls to SQL Server's <code><a href="">binary_checksum()</a></code> function when loading and saving entities, and I'd be interested if this is possible to do in a reasonably robust	http://feeds.feedburner.com/davesquared	crawl-002	refinedweb	20,943	55.03
Compute the length of a string, to a maximum number of bytes #include <string.h> size_t strnlen( const char * s, size_t maxlen ); libc Use the -l c option to qcc to link against this library. This library is usually included automatically. The strnlen() function computes the length of the string pointed to by s, not including the terminating null character, up to a maximum of maxlen bytes. The function doesn't check any more than the first maxlen bytes. The minimum of maxlen and the number of characters that precede the terminating null character. #include <stdio.h> #include <stdlib.h> #include <string.h> int main( void ) { printf( "%d\n", strnlen( "Howdy", 10 ) ); printf( "%d\n", strnlen( "Hello world\n", 5 ) ); printf( "%d\n", strnlen( "", 10 ) ); return EXIT_SUCCESS; } produces the output: 5 5 0	http://www.qnx.com/developers/docs/6.6.0_anm11_wf10/com.qnx.doc.neutrino.lib_ref/topic/s/strnlen.html	CC-MAIN-2018-43	refinedweb	133	74.39
The basics of the Python Enterprise Application Kit (PEAK) are covered in two previous installments of this column, "The Python Enterprise Application Kit" and "Scaling a new PEAK." In short, PEAK is a powerful framework for rapid component development and code reuse in Python. This installment covers the setuptools framework, a PEAK side project that provides easier package management and distribution than distutils. The setuptools module does a really good job of "getting out of the way." For example, if you download a package that was built using setuptools rather than distutils, installation should work just as you expect: the usual dance of python setup.py install. In order to accomplish this, a package bundled using setuptools includes the small bootstrap module ez_setup.py in the archive. The only caveat here is that ez_setup.py tries to download and install the necessary setuptools package in the background -- which depends, of course, on having a networked machine. If setuptools is already installed on the local machine, this background step is not necessary; but if it needs to be installed manually, much of the transparency is lost. Still, most systems nowadays have an Internet connection; taking a few special steps for non-networked machines is not especially burdensome. The real benefit of setuptools is not in doing roughly what distutils does -- even though it does enhance the capabilities of distutils and simplify what goes into a setup.py script. The greatest gain is setuptools' enhancement of package management capabilities. In a rather transparent way, you can find, download, and install dependencies; you can switch between multiple versions of a package, all of which are installed on the same system; you can declare requirements for specific versions of packages; and you can update to the latest versions of packages you use with a simple command. The most impressive part of all this is perhaps that fact that you can even utilize packages whose developers have done nothing whatsoever to consider setuptools compatibility. Let's take a closer look. The utility ez_setup.py is a simple script that bootstraps the rest of setuptools. Slightly confusingly, the easy_install script that comes with the full setuptools package does the same thing as ez_setup.py. The former assumes setuptools is already installed, however, so it skips the behind-the-scenes installation. Both versions accept the same arguments and switches. The first step in the process is simply downloading the small script ez_setup.py: Listing 1. Downloading the bootstrap script From there, you can run the script without any arguments to install the rest of setuptools (if you do not do this as a separate step, it will still get done the first time you install some other package). You should see something similar to this (depending, of course, on the version you are using): Listing 2. Bootstrapping setuptools All done. That's all you need to do to make sure setuptools is installed on your system. For many Python packages, all you need to do to install them is pass their name as a parameter to ez_setup.py or easy_install. Now that you've bootstrap loaded setuptools, you might as well use the internally simpler easy_install (though in practice it makes little difference which you choose). For example, let's say you want to install the package SQLObject. This can be as simple as Listing 3. Notice in the messages that SQLObject turned out to depend on a package called FormEncode; luckily, it is all taken care of for us: Listing 3. Installing a typical package As you can see from the messages, easy_install looks for metadata information about the package at, then finds the location for the actual download (in this case the egg archive lives right at cheeseshop.python.org; more on eggs soon). You can do more than just install the latest version of a package, as is the default. If you like, you can give easy_install specific version requirements. Let's try to install a post-beta version of SQLObject: Listing 4. Installing a minimum version of a package If (as is the case at the time of this writing) the latest version of SQLObject is less than 1.0, there is nothing to install. Installing "naive" packages The package SQLObject is already "setuptools aware"; but what if you want to install a package whose author has not given thought to setuptools? For example, before this article, I never used setuptools with my "Gnosis Utilities." Still, let's try installing the package, knowing only the HTTP (or FTP, SVN, CVS) location where it lives ( setuptools knows all these protocols). My download Web site has archives of the various Gnosis Utilities versions, named in a usual versioning fashion: Listing 5. Installing a setuptools-unaware package Happily for us, easy_install figured everything out. It looked in the given download directory, identified the highest available version number, unpackaged the archive, and repackaged it as an "egg" that was then installed. Importing gnosis now works fine in a script. But suppose you now need to test a script against a specific earlier version of Gnosis Utilities? Easy enough: Listing 6. Installing a particular version of a "naive" package There are actually two versions of Gnosis Utilities installed now, with 1.2.0 the active version. Switching the active version back to 1.2.1 is also easy: Listing 7. Changing the "active" version system-wide Of course, this makes only one version active at a time. But, by putting two lines at the top of an individual script like so, you can let the script choose the version it wants to use: Listing 8. Using a package version within a script With this stated requirement, setuptools will add the specific version (or the latest available, if the greater-than comparison is specified) when an import statement is run. Making a package more aware of setuptools I might like to let users install Gnosis Utilities without even knowing its download directory. This almost works, simply because Gnosis Utilities has an information listing at the Python Cheeseshop. Unfortunately, not having considered setuptools, I had created a slight "impedance mismatch" in my entry for Gnosis Utilities at python.org,. Specifically, the archives are named on a pattern like Gnosis_Utils-N.N.N.tar.gz. (The utilities are also archived as .zip and .tar.bz2, and the last few versions as win32.exe installers, all of which setuptools is equally happy with). But the project name on Cheeseshop is spelled slightly differently as "Gnosis Utilities." Oh well, a quick administrative version change at Cheeseshop created as a post-release version. Nothing was changed in the distribution archives themselves, just a little bit of metadata at Cheeseshop. With the slight tweak, we might use an even simpler install (note that for testing purposes, I ran an intervening easy_install -m to remove the installed package). Listing 9. Easy addition of setuptools awareness I omit the completion of the process, since it's identical to what you've already seen. The only change is that easy_install looks on Cheeseshop (in other words,) for metadata about a package matching the name specified, and uses that to look for an actual download location. In this case, the listed .ANNOUNCE file does not contain anything helpful, but easy_install is happy to keep looking at the other listed URL as well, which proves to be a download directory. An egg is a bundle that contains all the package data. In the ideal case, an egg is a zip-compressed file with all the necessary package files. But in some cases, setuptools decides (or is told by switches) that a package should not be zip-compressed. In those cases, an egg is simply an uncompressed subdirectory, but with the same contents. The single file version is handy for transporting, and saves a little bit of disk space, but an egg directory is functionally and organizationally identical. Java™ technology users who have worked with JAR files will find eggs very familiar.ools or ez_setup.py at all. For example, I put an egg for the PyYAML package in a working directory that I used for this article. I can use the package as easily as this: Listing 10. Eggs on the PYTHONPATH However, this sort of manipulation of the PYTHONPATH (or of sys.path within a script or Python shell session) is a bit fragile. Discovery of eggs is probably best handled within some newish magic .pth files. Any .pth files found in site-packages/ or on the PYTHONPATH are parsed for additional imports to perform, in a very similar manner to the way directories in those locations that might contain packages are examined. If you handle package management with setuptools, a file called easy-install.pth is modified when packages are installed, upgraded, removed, etc. But you may call your .pth files whatever you like (as long as they have the .pth extension). For example, here is my easy-install.pth: Listing 11. .pth files as configuration of egg locations The format is a bit peculiar: it is almost, but not quite, a Python script. Suffice it to say that you may add additional listed eggs in there; or better yet, easy_install will do it for you when it runs. You may also create as many other .pth files as you like under site-packages/, and each may simply list which eggs to make available. The above magic of installing a setuptools naive package (see Listing 6) worked only partially. That is, the package Gnosis_Utils got installed, but not quite completely. All the general functionality works, but a variety of supporting files were omitted when the egg was automatically generated -- mostly documentation files with a .txt extension and test files with .xml extensions (but also some miscellaneous README, .rnc, .rng, .xsl, and whatnot scattered around the subpackages). As it happens, all of these supporting files are "nice to have" and not strictly required. Still, we would like to include all the supporting files. The setup.py script for Gnosis_Utils is quite complex, actually. Besides listing basic metadata, in 467 lines of code, it performs a whole bunch of testing for Python version capabilities and bugs; works around glitches in old versions of distutils; falls back to skipping installation of non-supported parts (for example, if pyexpat is not included in your Python distribution); handles OS line-ending convention conversion; creates multiple archive/installer types; and rebuilds the MANIFEST file in response to these tests. The capability to do all this work is mostly thanks to the package co-maintainer, Frank McIngvale; and it lets Gnosis_Utils successfully install as far back as Python 1.5.1, if necessary (with reduced capabilities in earlier versions). The quick moral here is that what I am about to show you does not do as much as the complex distutils script: it simply assumes that a "normal"-looking and recent version of Python is installed. That said, it is still impressive just how easy setuptools can make an installation script. As a first try, let's create a setup.py script borrowing from the setuptools manual, and try creating an egg using it: Listing 12. setuptools setup.py script This little effort works; or at least it sort of works. It really does create an egg with these few lines, but the egg has the same shortcoming as the version easy_install created: it lacks the support files that are not named .py. So let's try again, only a little harder: Listing 13. Adding the missing package_data It turns out that is all you need to do. Of course, in practice you'll often want to fine tune this a bit. For example, more realistically, this might list the following: Listing 14. Packaging specific file types Which translates as, include the .txt files under the doc/ subpackage, all the .xml files under the xml/ subpackage, and all the .rnc files under the xml/relax/ subpackage. I really just scratched the surface of the customization you can perform with setuptools-aware distributions. For example, once you have a distribution (either in the preferred egg format or another archive type), you can automatically upload the archive and metadata to Cheeseshop with a single command. Obviously, a complete setup.py script should contain the same detailed metadata that your old distutils scripts contained; I skipped that for ease of presentation, but the argument names are compatible with distutils. It takes a little while to get fully comfortable with setuptools' large set of capabilities, but it really makes both maintaining your own packages and installing outside packages much easier than the distutils baseline. And if all you care about is installing packages, pretty much everything you need to know is contained in this introduction; the complexity only comes with describing your own packages, and that complexity is still less than required to grok distutils. Learn - Read David's previous columns on PEAK: "The Python Enterprise Application Kit" (developerWorks, May 2004) and "Scaling a new PEAK" (developerWorks, September 2005). - The PEAK home page is the place to start for an introduction to the library as a whole. - The full manual for setuptoolsis available online. - In the developerWorks Linux zone, find more resources for Linux developers. - Stay current with developerWorks technical events and Webcasts. Get products and technologies - At the Python Cheese Shop, get the latest version of setuptools. - Gnosis Utilities, David's handy set of Python libraries, are available from the Cheese Shop. -.	http://www.ibm.com/developerworks/linux/library/l-cppeak3.html	crawl-002	refinedweb	2,244	63.49
Logging in Browser Using a structured logger in your frontend project You will not find a Node.js application that does not use some level of logging to communicate program progress. However, when we look at the frontend applications, we rarely see any logging. This is primarily because: - Frontend developers already get a lot of feedback through the UI. consoleobject has a bad history of cross-browser compatibility (e.g. in IE8 console object was only available when the DevTools panel was open. Needless to say – this caused a lot of confusion.) I guess for the reasons above, it didn’t surprise me when another frontend developer asked me how are we going to log errors in our React project: I’m wondering about the best practices of logging in a browser. Should logs be freely used everywhere and leave it up to the bundler to handle removal of those? To reduce the size footprint perhaps? I read that some older browsers do not have consoledefined. So it’s advisable to remove them or handle its presence. A summary of our conversation is as follows: - Log statements are not going to measurably affect the bundle size. - It is true that consoleobject has not been standardised to this day. However, all current JavaScript environments implement console.log. console.logis enough for all in-browser logging. - We must log all events that describe important application state changes, e.g. API error. - Log volume is irrelevant*. - Logs must be namespaced and have an assigned severity level (e.g. trace, debug, info, warn, error, fatal). - Logs must be serializable. - Logs must be available in production. Given all of the above, what is the best way to log in a frontend application? Writing your Logger The first thing to know is that outside of ad-hoc logging for debugging purposes, you mustn’t use console.log directly. Lack of a console standard aside (there is a living draft), using console.log restricts you from pre-processing and aggregating logs, i.e. everything that you log goes straight to console.log. You want to have control over what gets logged and when it gets logged because once the logs are in your browser’s devtools, your capability to filter and format logs is limited to the toolset provided by the browser. Furthermore, logging does come at a performance cost. In short, you need an abstraction that enables you to establish conventions and control logs. That abstraction can be as simple as: const MyLogger = (...args) => { console.log(...args); }; You would pass-around and use MyLogger function everywhere in your application. Having this abstraction already allows you to control exactly what/ when gets logged, e.g. you may want to enforce that all log messages must describe log severity: type LogLevelType = 'debug' \| 'error' \| 'info' \| 'log' \| 'trace' \| 'warn';const MyLogger = (logLevel: LogLevelType, ...args) => { console[logLevel](...args); }; You may even opt-in to disable all logs by default and print them only when a specific global function is present, e.g. type LogLevelType = 'debug' \| 'error' \| 'info' \| 'log' \| 'trace' \| 'warn';const Logger = (logLevel: LogLevelType, ...args) => { if (globalThis.myLoggerWriteLog) { globalThis.myLoggerWriteLog(logLevel, ...args); } }; The advantage of this pattern is that nothing gets written by default to console (no performance cost; no unnecessary noise), but you can inject custom logic for filtering/ printing logs at a runtime, i.e., you can access your minimized production site, open devtools and inject custom to log writer to access logs. globalThis.myLoggerWriteLog = (logLevel, ...args) => { console[logLevel](...args); }; Earlier I mentioned that log volume is irrelevant (with an asterisk). How much you log is indeed irrelevant (calling a mock function does not have a measurable cost). However, how much gets printed and stored has a very real performance cost and processing/ storage cost. This is true for frontend and for backend programs. Having such an abstraction enables you to selectively filter, buffer and record a relevant subset of logs. At the end of the day, however you implement your logger, having some abstraction is going to be better than using console.log directly. My advice is to restrict Logger interface to as little as makes it useable: smaller interface means consistent use of the API and enables smarter transformations, e.g. all my loggers require log level, a single text message, and a single, serializable object describing all supporting variables. Using a Logging framework Finally, before you head out to implement your own abstraction, I suggest to evaluate if Roarr logger (about which I have blogged earlier) meets your requirements. Roarr requires no initialisation, it works in Node.js and browser, it allows structured logs and it decouples transports. Starting to use Roarr is simple and it comes with several nifty features, including a variation of those described in this article. import log from 'roarr';log('Hello, I am your first structured log.'); Proceed to Roarr documentation to learn my motivation for creating Roarr and how to get started.	https://gajus.medium.com/logging-in-browser-2f053dbe69df?source=post_page-----2f053dbe69df--------------------------------	CC-MAIN-2021-04	refinedweb	822	56.55
Today’s clients seem to be getting more and more demanding regarding the flexibility of their applications and the speed in which modifications can be made. In this article, I will show you how to design applications with extensibility points so that they will grow with the clients’ needs as well as provide a way to “swap” functionality in and out as needed. Throughout my years in software development, there have been many concepts and paradigms introduced in writing code as well as many methodologies for defining how software should be developed. For the most part, each has built on the previous, enhancing the development process each time. Object-oriented programming redefined how we think of entities within an application and communicate with them. SOA showed us how to expose object-oriented entities in a way that they can service similar and dissimilar clients. Several years ago, the design-pattern craze hit the industry with the publishing of the famous GoF book (see sidebar “Additional References”). All these things put together have inspired the creativity of many developers, including me. I’m going to show you how to use your existing OOP and pattern knowledge to develop applications in a way that they can be changed and/or enhanced with minimum effort and in a clean, elegant, and efficient manner. Extensibility Patterns Throughout the course of this article, I’m going talk about three different patterns that I use to make my applications extensible. None of these is absolutely defined in any patterns manual, though each bears resemblance to one or more patterns in the GoF catalog. Providers This pattern has its roots in the Strategy pattern and it lets you design your data and behavior in an abstraction so that you can swap out implementation at any time. Plug-Ins This builds on the same abstraction design I’ll use in writing providers and lets you build sections of your site in swappable modules. In a way they are similar to providers but where you generally use providers to obtain information, you use plug-ins typically to perform tasks; though many will argue quite successfully that their definitions can be interchangeable. Modules Modules have their roots in the Chain of Responsibility pattern and take plug-ins to the next level by allowing you to define many plug-ins within one class, thus centralizing your extensibility capability in your application. To better illustrate how the three patterns I’m going to show you evolve, I’ll start by describing a very trivial 3-step process that I’ll build on as the article progresses. I’ll code this process concretely first, and then start applying my three patterns to it. The 3-step process will involve obtaining the name of a text file, reading in string data from it, and logging that data to another file. Doing it Concretely I’ll first start by writing a class that will house the functionality I want for my 3-step process. I’ll call this class FileReader. Here’s the interface for the FileReader class. You can find the complete code in Listing 1. In VB: Public Function GetFileName() As String Public Function GetFileData(ByVal file As String) As String Public Sub LogTextData(ByVal data As String) In C#: public string GetFileName() public string GetFileData(string file) public void LogTextData(string data) From what this code shows, the GetFileName method is returning the name of a file, which FileReader then sends into the GetFileData method to retrieve a string of data, which it then sends into the LogTextData method. Now, say you were building an application that was going to run this little 3-step process. Integrating this into a form or a controller class of some kind would not be difficult at all and quite well accepted by most developers in the industry. Unfortunately, if anything ever changes with the way the application obtains a file name or the data, it would involve coming back into this code and changing it appropriately. A client can use my FileReader class like so: In VB: Dim o_FileReader As FileReader = New FileReader() Dim s_File As String = o_FileReader.GetFileName() Dim s_Data As String = _ o_FileReader.GetFileData(s_File) If s_Data <> "" Then o_FileReader.LogTextData(s_Data) End If In C#: FileReader o_FileReader = new FileReader(); string s_File = o_FileReader.GetFileName(); string s_Data = o_FileReader.GetFileData(s_File); if (s_Data != "") { o_FileReader.LogTextData(s_Data); } So what I’m going to do is abstract the interface and separate it from the implementation. A client application, be it a class or a form, will then communicate only through the abstraction I’m about to design. In the interest of even greater flexibility, I’m going to generalize this process even further. I’m going to go from: - GetFileName - GetFileData - LogTextData to: - GetSource - GetData - LogData Notice the “from” can fit easily into the “to”, though not vice-versa. I came up with this by pretending to be the client, and asking myself exactly what do I need; then coming up with a more generic process that still has the capability of feeding me exactly what I needed. Now all I need to do is turn this into a provider model. Providers The provider model will allow me to define my three steps in an abstraction, be it an interface or an abstract class. In the interest of simplicity, I’m going to use an interface, so let’s start with that. In VB: Public Interface IDataProvider Function GetSource() As String Function GetData(ByVal source As String) As String Sub LogData(ByVal data As String) End Interface In C#: public interface IDataProvider { string GetSource(); string GetData(string source); void LogData(string data); } Now I have an interface to which I can apply any implementation I want; so long as it meets the signature and return types defined-basic polymorphism. It is pretty customary to have a project set up for these abstractions. Then, later when you or somebody else wants to write a different implementation class, they need only to reference this one assembly. When I first wrote my little 3-step process, I did so for a reason; my application had a need and that process filled it; that has not gone away. Only now, I want to accomplish it in a way that I can change it later and not touch my client application. Initially I’ll have to change my client code, which currently instantiates and uses the FileReader class, but that should be the last time I have to touch that class. Remember I designed the interface in such a way that in the future, the “source” can change; it doesn’t necessarily have to be a file name. And the data obtained does not always necessarily have to come from a file. If this ever changes in the future, my design can accommodate it. The only requirement is that you must represent the “source” as a string and that you must use it to obtain string data, which you will later log. So now that I have an interface that serves as my abstraction, I’m going to write my first provider based on it. Appropriately, I will call this class TextFileProvider and it will reside in its own project, producing its own assembly. I’m going to include the method signatures for my class here, but you can find the full listing in Listing 2. In VB: Namespace Providers Public Class TextFileProvider Implements IDataProvider Protected Function GetSource() As String Implements _ Core.IDataProvider.GetSource Protected Function GetData( _ ByVal source As String) As String Implements _ Core.IDataProvider.GetData Protected Sub LogData( _ ByVal data As String) _ Implements Core.IDataProvider. LogData End Class End Namespace In C#: namespace Providers { public class TextFileProvider : IDataProvider { string IDataProvider.GetSource() string IDataProvider.GetData( string source) void IDataProvider. LogData(string data) } } The implementation for these methods in this class is identical to my original FileReader class. Because the signatures are also the same, it can plug quite nicely into my client application. So now I have to change my client for what will be the only time. Instead of directly instantiating a class like FileReader, the client will only communicate through the IDataProvider interface. I’ll take advantage of the app.config file to determine which implementation of IDataProvider I will use; of which so far I only have one: TextFileProvider. I’ll keep the additions to the app.config file simple for this first example, so I’ll just use the <appSettings> section. For the later examples, I’ll use custom configuration sections though I will not explain how they work in detail; that is the subject of another article. <add key="dataProvider" value="Providers.TextFileProvider, Providers"/> The text in the value attribute is called standard .NET type notation. It is the fully qualified class (namespaces and all), a comma, and the assembly in which it resides. If the class is in the current assembly, that is the one hosting the app.config file, you can leave out the assembly name here. However that will be contrary to what I’m trying to solve here, and that is to NOT have to adjust the client application if I want to modify the behavior defined in the provider. The assembly in which the provider class resides will NOT be added to the client in the conventional manner, by “Adding a Reference”. This assembly needs only to be “accessible” to the client. This means all I have to do is drop it into the client’s Bin folder. Now that I have a place to go looking for what implementation of my provider interface I need to use, I’m going to remove the client’s usage of FileReader and insert my new code. I’ll do this in a couple of steps for clarity. In VB: Dim s_Provider As String = _ ConfigurationManager. AppSettings("dataProvider") Dim o As Object = _ Activator.CreateInstance( _ Type.GetType(s_Provider)) Dim o_Provider As IDataProvider = _ DirectCast(o, IDataProvider) In C#: string s_Provider = ConfigurationManager. AppSettings["dataProvider"]; Object o = Activator.CreateInstance( Type.GetType(s_Provider)); IDataProvider o_Provider = o as IDataProvider; The first line obtains the value from the app.config file, the type notation I described earlier. The second line creates an instance of the class described in the string variable using a technique similar to the old CreateObject you used to use in Visual Basic 6.0. The CreateInstance method in the Activator class lets you instantiate an object when the object type is in string form. However, since the CreateInstance method does not know what it’s instantiating (since it’s in a string) it returns a standard object type. The last task now is to get a type with which I can actually work. However, I don’t want to do this by referencing a concrete class; that would defeat my whole purpose. But since the client just needs a “source” in string form and “data” in string form, it should not care how it gets it; that’s why I created an interface, and it’s through that interface that I’m going to communicate. That’s what the third line of code accomplishes; it casts the object variable to the interface type. I now have a variable, “o_Provider”, which I can use to obtain a source, obtain data, and log data. Since the type on which I ran the CreateInstance against is “Providers.TextFileProvider”, the interface methods will use the implementation I defined there. In VB: Dim s_Source As String = o_Provider.GetSource() Dim s_Data As String = _ o_Provider.GetData(s_Source) If s_Data <> "" Then o_Provider.LogData(s_Data) End If In C#: string s_Source = o_Provider.GetSource(); string s_Data = o_Provider.GetData(s_Source); if (s_Data != "") { o_Provider.LogData(s_Data); } So now, I’ve still met my application’s original requirements but can change the behavior easily and can even swap it out. Let me prove that to you. Fast forward the clock six months. The company for which I wrote this application has decided that the data store that housed the data my little application is processing is now going to come from a database as opposed to from a text file. However, it will still be string data and my application will still need to log it. Well, thanks to my provider model, all I need to do is to write a new provider class that implements my same interface and replace the entry in the app.config. The new provider, appropriately named TableDataProvider, is listed in full in Listing 3. So that I don’t have to prolong this article with unnecessary details, I won’t describe the layout of the database in use here, but if you read through the code, you’ll see that my “source” now went from the name of a file to a string used in a table. I use that string to return data from another table, so you see I still maintain the contract between the interface and the client, though the implementation is now very different. By replacing the line in the app.config to look like this: <add key="dataProvider" value="Providers.TableDataProvider, Providers"/> The client can now continue to run without ever knowing that the source of the data changed. Wrapping It in a Factory As an added bonus, let me show you a really cool way you can wrap all the code that determines what provider to use, instantiates it, casts it, and accesses the interface members into a static (shared) factory class. This is the same pattern that ASP.NET uses with the Membership, Roles, and Profile classes. Let me describe the Membership class so you can get an idea about what I’m going to do for the application. In ASP.NET, you can create a user using the Membership class by saying: Membership.CreateUser( all arguments here… ASP.NET uses a provider model behind the Membership class in order to determine how it will create a user. When you execute a statement like the one above, you execute the static constructor of the Membership class. It is in here that the application reads the app.config and makes the decision as to what provider to use. By the time you call the CreateUser method, the class has a member variable that you’ve declared as the membership abstraction (in this case, a base class called MembershipProvider) and instantiated as the appropriate provider class as defined in the app.config. The CreateUser method will delegate the call to the CreateUser method of said variable, and then it executes the appropriate implementation. This is what I’m going to do with the provider model. So here are the steps in my plan: - Create a class that will contain static (shared) members only. - Declare a class-level private static variable of type IDataProvider. - In the static constructor, execute the code that will fill the static IDataProvider variable. - Set up static methods that mimic those of the IDataProvider interface. - In each of the methods, call the corresponding method in the IDataProvider variable. If I call my class, AcmeFactory, it would look like this (note that Visual Basic modules behave like C# static classes): In VB: Public Module AcmeFactory Sub New() o_Provider = GetDataProvider() End Sub Private o_Provider As IDataProvider = Nothing Public Function GetDataProvider() As _ IDataProvider Dim s_Provider As String = _ ConfigurationManager. AppSettings(_ "dataProvider") Dim o As Object = _ Activator. CreateInstance( _ Type.GetType( S_Provider)) o_Provider = DirectCast(o, IDataProvider) Return o_Provider End Function Public Function GetSource() As String Return o_Provider.GetSource() End Function Public Function GetData() As String Dim s_Source As String = _ o_Provider.GetSource() Dim s_Data As String = _ o_Provider.GetData(s_Source) Return s_Data End Function Public Sub LogData(ByVal data As String) o_Provider.LogData(data) End Sub End Module In C#: public static class AcmeFactory { static AcmeFactory() { o_Provider = GetDataProvider(); } private static IDataProvider o_Provider = null; public static IDataProvider GetDataProvider() { string s_Provider = ConfigurationManager.AppSettings[ "dataProvider"]; Object o = Activator.CreateInstance( Type.GetType(s_Provider)); o_Provider = o as IDataProvider; return o_Provider; } public static string GetSource() { return o_Provider.GetSource(); } public static string GetData() { string s_Source = o_Provider.GetSource(); string s_Data = o_Provider.GetData(s_Source); return s_Data; } public static void LogData(string data) { o_Provider.LogData(data); } } Now in order to actually use the provider, the client simply has to do the following: In VB: Dim s_Data As String = AcmeFactory.GetData() If s_Data <> "" Then AcmeFactory.LogData(s_Data) End If In C#: string s_Data = AcmeFactory.GetData(); if (s_Data != "") { AcmeFactory.LogData(s_Data); } Notice that I’m not even calling the GetSource method here; instead I’ve programmed the GetData to do that for me in the factory class. You can inject the provider model in many places throughout an application. If you ever find yourself looking at a piece of code and wondering if it ever may be subject to change, think about using this pattern there. If you ever find yourself looking at a process and wondering if it may be one day swapped out, removed, or enhanced, you may want to look at a plug-in model. Plug-Ins Plug-ins are very similar to the provider model and, in fact, can be considered the same model; just used in a different way. Whereas you can use a provider to determine what implementation to use for a certain process, you can use plug-ins to inject functionality into a process that may be either swapped out later, removed, or be made to grow. It’s a little difficult to explain without showing you some code so let’s jump right in. Suppose the need has arisen for me to further enhance my 3-step process with the ability to send out an e-mail to some managers regarding the data my process handled. I can very easily just place that functionality in the client just after I “log the data”, but what if I want to make that subject to change in the future? Or even better, what if I can anticipate that a manager will later ask me to do something else with the data even after I’ve sent out an e-mail, like archive it somewhere? Instead of adding this and any other functionality to my client, I’m going to inject a plug-in model and have the client interact with that. The path I’ll take to do this is very similar to that of the providers, but remember that earlier I did say that each of the patterns would be building on the previous. The first step is to define an abstraction for my plug-in. I’m going to be calling this plug-in after I “log my data” so I’m going to call the interface appropriately, IPostLogPlugin. And I don’t really know what each plug in will do; however, I do know that it will do something with the data I just finished logging, so the interface will define a single method that receives string data in an argument. In VB: Public Interface IPostLogPlugin Sub PerformProcess(ByVal data As String) End Interface In C#: public interface IPostLogPlugin { void PerformProcess(string data); } Now, before I actually write any classes that use this interface, I’m going to inject the client with code that run these potential plug-ins. Where I put this code is called a “point of extensibility”. And I’m going to put a point of extensibility directly after my logging code. Also, the code I’m going to insert will account for the possibility of more than one such plug-in being installed. Plug-ins that are written to my new interface get installed in the app.config just like the provider was, but these will go in their own configuration section called “postProcessing” and be read into a collection of objects that adheres to the details in the configuration section. Details on writing a custom configuration section is way beyond the scope of this article, but the code I’ll put here should be pretty self-explanatory. In VB: Dim s_Data As String = AcmeFactory.GetData() If s_Data <> "" Then AcmeFactory.LogData(s_Data) End If Dim section As Object = _ ConfigurationManager.GetSection(" _ postProcessing") Dim o_PlugIns As List(Of PluginInfo) = _ DirectCast(section, List(Of PluginInfo)) For Each o_PluginInfo As PluginInfo In o_Plugins Dim o As Object = Activator.CreateInstance( _ Type.GetType(o_PluginInfo. PluginType)) Dim o_PlugIn As IPostLogPlugin = _ DirectCast(o, IPostLogPlugin) o_Plugin.PerformProcess(s_Data) Next In C#: string s_Data = AcmeFactory.GetData(); if (s_Data != "") { AcmeFactory.LogData(s_Data); } object section = ConfigurationManager.GetSection(" postProcessing"); List<PluginInfo> o_Plugins = section as List<PluginInfo>; foreach (PluginInfo o_PluginInfo in o_Plugins) { object o = Activator. CreateInstance( Type.GetType(o_PluginInfo. PluginType)); IPostLogPlugin o_Plugin = o as IPostLogPlugin; o_Plugin.PerformProcess(s_Data); } As you can see, I’m reading the collection of plug-ins into a variable called “o_PlugIns”. I’m going to write two plug-in classes called EmailProcessing and ArchiveProcessing, and they’ll go into the app.config file like this: <postProcessing> <process name="email" description="Send notification emails" type="PlugIns. EmailProcessing, PlugIns" /> <process name="archive" description="Check for archive needs" type="PlugIns. ArchiveProcessing, PlugIns" /> </postProcessing> Given the contents of this app.config section and the previous code, I’m looping through each plug-in definition, creating the class stored in the “type” attribute, and then casting it to the IPostLogPlugin interface. After which I simply call the PerformProcess method, sending in my string data. What the plug-in classes do is unknown to the client, as is how many plug-ins are installed. All I have left to do is write my plug-in classes. I’m not going to actually show any implementation details for sending e-mails or archiving data but you’ll certainly get the idea of what’s going on. In VB: Public Class EmailProcessing Implements IPostLogPlugin Protected Sub PerformProcess( _ ByVal data As String) Implements _ Core.IPostLogPlugin. PerformProcess ' take data and e-mail it ' somewhere End Sub End Class Public Class ArchiveProcessing Implements IPostLogPlugin Protected Sub PerformProcess( _ ByVal data As String) Implements _ Core.IPostLogPlugin. PerformProcess ' take data and archive it End Sub End Class In C#: public class EmailProcessing : IPostLogPlugin { void IPostLogPlugin. PerformProcess( string data) { // take data and e-mail it // somewhere } } public class ArchiveProcessing : IPostLogPlugin { void IPostLogPlugin. PerformProcess( string data) { // take data and archive it } } As in the case of providers, the assembly in which the plug-in classes reside is not directly referenced by the client but merely has to be accessible (meaning just dropped into its Bin folder). Though I’m not going to do it here, with a little creativity you can probably wrap some of the client’s work into a factory or helper class as I did in the provider model. The plug-in model is great and you can use it to inject as many “points of extensibility” in your application as you want. And you can do this even if you don’t have any plans to write an immediate plug-in that you call at a specific point-just securing your application for the future. The drawback comes when you have more than one type of plug-in, which may each require its own interface. At this point, you may be giving your developers too many interfaces to try to remember. That’s where extensibility modules come in handy. Extensibility Modules Extensibility modules let you consolidate your plug-ins into a centralized class, giving all your developers one place to go to in order to figure out what kind of extensibility is available to them for a given application. If you’re familiar with the concept of HttpModules, you’re going to feel right at home with what I’m about to talk about. In writing plug-ins, I showed you how to write an interface for each type of plug-in; with the signature of the interface member(s) identifying the data that the plug-in class needed for its processing. In extensibility modules, there’s a little more work but it’s a lot more organized. I’m going to show you how to do this by writing what would otherwise be three different plug-ins. One serves the same purpose as the one in our plug-ins example, a “post log” plug-in, which I’m actually calling “post processing”. Another will be a “pre-processing” plug-in, and a third is a “check data source” plug-in. The points of extensibility I’ll insert into my client will be as follows: - The “Check Data Source” plug-in process will run immediately following the “GetSource” method in my provider. This execution will also determine if you should continue or not. - The “Pre-Process” plug-in process will run just before you “log” the data. - The “Post-Process” plug-in process will run immediately after you “log” the data. The cool thing here is that I’m going to do this using just one interface. But because of that, I’m going to need an EventArgs-based class for each of my three plug-in scenarios. Like any conventional EventArgs-based class, each one will contain the data that I need to get from my client app into the “plug-in” process code and back. In VB: Public Class CheckDataSourceEventArgs Inherits CancelEventArgs Public Sub New(ByVal source As String) _Source = source End Sub Protected _Source As String Public Property Source() As String Get Return _Source End Get Set(ByVal value As String) _Source = value End Set End Property End Class Public Class PreProcessDataEventArgs Inherits EventArgs Public Sub New(ByVal data As String) _Data = data End Sub Protected _Data As String Public Property Data() As String Get Return _Data End Get Set(ByVal value As String) _Data = value End Set End Property End Class Public Class PostProcessDataEventArgs Inherits PreProcessDataEventArgs Public Sub New(ByVal data As String) MyBase.New(data) End Sub End Class In C#: public class CheckDataSourceEventArgs : CancelEventArgs { public CheckDataSourceEventArgs( string source) { _Source = source; } protected string _Source; public string Source { get { return _Source; } set { _Source = value; } } } public class PreProcessDataEventArgs : EventArgs { public PreProcessDataEventArgs( string data) { _Data = data; } protected string _Data; public string Data { get { return _Data; } set { _Data = value; } } } public class PostProcessDataEventArgs : PreProcessDataEventArgs { public PostProcessDataEventArgs( string data) : base(data) { } } As you can see, the PostProcessDataEventArgs is going to need the same data as the PreProcessDataEventArgs. To make things simpler, I’m just inheriting one from the other. Now that I have an EventArgs class to carry information to and from each plug-in process, I’m going to create a class that will use these EventArgs classes. Basically this class, called ModuleEvents, will contain a set of properties, one for each plug-in process I want to define. The type for each property will be a delegate that defines a signature of the corresponding EventArgs-based class. The member variables that each property will wrap will be of the same delegate type. Does that sound confusing enough? Take a look at the code and it should clear things up. The first thing I need is my delegate types, but in actuality I only need one, thanks to the wonderful world of .NET Generics: In VB: Public Delegate Sub AcmeModuleDelegate(Of T) _ (ByVal e As T) In C#: public delegate void AcmeModuleDelegate<T>(T e); Now the property types can all use the same delegate type, but each with their own value for the generic. Let’s first create the member variables: In VB: Private _CheckDataSource As AcmeModuleDelegate( _ Of CheckDataSourceEventArgs) Private _PreProcessData As AcmeModuleDelegate( _ Of PreProcessDataEventArgs) Private _PostProcessData As AcmeModuleDelegate( _ Of PostProcessDataEventArgs) In C#: private AcmeModuleDelegate <CheckDataSourceEventArgs> _CheckDataSource; private AcmeModuleDelegate <PreProcessDataEventArgs> _PreProcessData; private AcmeModuleDelegate <PostProcessDataEventArgs> _PostProcessData; Now for the public properties that expose the member variables: In VB: Public Property CheckDataSource() As _ AcmeModuleDelegate(Of CheckDataSourceEventArgs) Get Return _CheckDataSource End Get Set(ByVal value As AcmeModuleDelegate( _ Of CheckDataSourceEventArgs)) _CheckDataSource = Value End Set End Property Public Property PreProcessData() As _ AcmeModuleDelegate(Of PreProcessDataEventArgs) Get Return _PreProcessData End Get Set(ByVal value As AcmeModuleDelegate( _ Of PreProcessDataEventArgs)) _PreProcessData = Value End Set End Property Public Property PostProcessData() As _ AcmeModuleDelegate(Of PostProcessDataEventArgs) Get Return _PostProcessData End Get Set(ByVal value As AcmeModuleDelegate( _ Of PostProcessDataEventArgs)) _PostProcessData = Value End Set End Property In C#: public AcmeModuleDelegate <CheckDataSourceEventArgs> CheckDataSource { get { return _CheckDataSource; } set { _CheckDataSource = value; } } public AcmeModuleDelegate <PreProcessDataEventArgs> PreProcessData { get { return _PreProcessData; } set { _PreProcessData = value; } } public AcmeModuleDelegate <PostProcessDataEventArgs> PostProcessData { get { return _PostProcessData; } set { _PostProcessData = value; } } Now, an instance of ModuleEvents will contain properties that are delegates. As you know, a delegate can have one or more function pointers in its invocation list. Now it’s time to write the interface that I’ll use to write plug-ins later. As I said earlier, instead of having a different interface for each plug-in, I’m going to have only one, which looks like this: In VB: Public Interface IAcmeModule Sub Initialize(ByVal events As ModuleEvents) End Interface In C#: public interface IAcmeModule { void Initialize(ModuleEvents events); } Notice that I have only one method, Initialize, and it receives an argument of the type ModuleEvents, which I just created. Now, the best way to continue is to write a plug-in using this new model. From what you see so far, developers only have one interface they need to know about to extend this application. So I’m going write a new class in a new project called NotificationModule. Note that this class will perform the same process as the EmailProcessing plug-in I coded earlier. The class will implement the IAcmeModule interface and implement the Initialize method. In this method, I’ll access the events argument, whose properties are delegates. The IntelliSense itself will tell me what my possible extensibility points are. Since each one is a delegate, I can just wire a method in this class to that delegate, effectively adding to its invocation list. In VB: Public Class NotificationModule Implements IAcmeModule Public Sub Initialize(ByVal _ events As _ Core.ModuleEvents) Implements _ Core.IAcmeModule.Initialize events.PostProcessData = _ New AcmeModuleDelegate( _ Of PostProcessDataEventArgs)( _ AddressOf events_PostProcessData) End Sub Private Sub events_PostProcessData( _ ByVal e As PostProcessDataEventArgs) ' perform e-mail functionality ' with processed data End Sub End Class In C#: public class NotificationModule : IAcmeModule { void IAcmeModule.Initialize( ModuleEvents events) { events.PostProcessData += events_PostProcessData; } void events_PostProcessData( PostProcessDataEventArgs e) { // perform e-mailing of processed data } } As you can see, within the module class itself, I made the decision as to what extensibility point I want to tap into. The client will also have to be changed. As opposed to having the client look for a specific plug-in type to instantiate, it will read in ALL modules and immediately loop through them and call their Initialize method. This will have built the invocation lists of any delegates I’ve wired in any of the modules. In VB: Dim section As Object = _ ConfigurationManager.GetSection( _ "dataProcessingModules") Dim o_Modules As List(Of String) = _ DirectCast(section, List(Of String)) Dim o_FilterEvents As New ModuleEvents() For Each s_ModuleType As String In o_Modules Dim o As Object = _ Activator.CreateInstance( _ _Type.GetType(s_ModuleType)) Dim o_Module As IAcmeModule = _ DirectCast(o, IAcmeModule) o_Module.Initialize(o_FilterEvents) Next In C#: object section = ConfigurationManager.GetSection( "dataProcessingModules"); List<string> o_Modules = section as List<string>; ModuleEvents o_FilterEvents = new ModuleEvents(); foreach (string s_ModuleType in o_Modules) { object o = Activator.CreateInstance( Type.GetType(s_ModuleType)); IAcmeModule o_Module = o as IAcmeModule; o_Module.Initialize(o_FilterEvents); } Notice in this code that I declared the ModuleEvents object, o_FilterEvents, outside the loop. And that I sent the same object into each module. This way, by the end of the loop, the delegate properties in the object may contain zero or more method pointers. All this happens somewhere at the beginning of my application. I still have to decide where within the body of the application I am going to insert extensibility points, just like I called my IPostLogPlugin-based classes from a specific point in the application. Upon making these decisions, I’ll check for the appropriate property in o_FilterEvents that corresponds to the extensibility point I am in within my application. Checking said property for a value other than null (nothing) is enough to determine if there are items in the invocation list for the delegate. At that point, it simply becomes a matter of invoking the delegate. The following is the extensibility point I am inserting just after I obtained a “data source” (remember the GetSource method). In VB: Dim b_Cancel As Boolean = False If Not o_FilterEvents. CheckDataSource _ Is Nothing Then Dim o_EventArgs As _ CheckDataSourceEventArgs = _ New CheckDataSourceEventArgs( s_Source) o_FilterEvents. CheckDataSource.Invoke( _ o_EventArgs) b_Cancel = o_EventArgs.Cancel End If In C#: bool b_Cancel = false; if (o_FilterEvents.CheckDataSource != null) { CheckDataSourceEventArgs o_EventArgs = new CheckDataSourceEventArgs( s_Source); o_FilterEvents. CheckDataSource.Invoke( o_EventArgs); b_Cancel = o_EventArgs.Cancel; } Take notice of the Boolean variable I’m declaring before I fire off this event and setting to the Cancel value that comes back from my EventArgs class. I’ve designed this event so that the code you can inject has the option to set the Cancel property to true or false. An example of code that taps into this event would look like this: In VB: Public Class ProfanityFilter Implements IAcmeModule Public Sub Initialize(ByVal events As _ Core.ModuleEvents) _ Implements Core.IAcmeModule.Initialize events.CheckDataSource = New AcmeModuleDelegate(Of CheckDataSourceEventArgs) (AddressOf events_CheckDataSource) End Sub Private Sub events_CheckDataSource( _ ByVal e As CheckDataSourceEventArgs) If e.Source.ToUpper(). IndexOf("BAD") _ > -1 Then e.Cancel = True End If End Sub End Class In C#: public class ProfanityFilter : IAcmeModule { void IAcmeModule.Initialize( ModuleEvents events) { events.CheckDataSource += events_CheckDataSource; } void events_CheckDataSource( CheckDataSourceEventArgs e) { if (e.Source.ToUpper(). IndexOf("BAD") > -1) e.Cancel = true; } } This module taps into the CheckDataSource event and checks to see if the data source coming in contains the word “BAD”. If it does, it sets the Cancel property to true. Now this will make more sense if you go back to the code I added to the client (the one that worked with the b_Cancel variable). The code that would follow will check the value of the b_Cancel variable to determine if I should continue any further with any kind of processing. Where it gets a little more complicated is in the case of more than one module tapping into this event. With the code that executes the Invoke method, it will fire all the modules that are wired to the CheckDataSource events, one after the other. Remember, this happens because my initialization routine sent and received the same ModuleEvents object to each module’s Initialize method. Now think of the order of events here (no pun intended). If I have three modules that tap into this event, each checking the data source for something different, the first one that gets executed will receive the initial value of the Cancel property, which is false. If the code in any module changes that value, the next module that the code executes will contain that new value, since the Invoke method is getting called once with the one EventArgs object. This means that it is up to me to code the module event to check the “e.Cancel” before I execute any of the logic in the event. In this case, a properly written module that taps into the CheckDataSource event should look like this: In VB: Private Sub events_CheckDataSource( _ ByVal e As CheckDataSourceEventArgs) If Not e.Cancel Then If e.Source.ToUpper(). IndexOf("BAD") _ > -1 Then e.Cancel = True End If End If End Sub In C#: void events_CheckDataSource( CheckDataSourceEventArgs e) { if (!e.Cancel) { if (e.Source.ToUpper().IndexOf("BAD") > -1) e.Cancel = true; } } If you code all the modules this way, as soon as any module that intercepts this event sets the e.Cancel property to true, no other module’s CheckDataSource event will process any code. I do have another choice for this kind of logic, which is probably a bit safer. The previous examples put the responsibility of check for “cancel” in the module’s code. But not all your modules may necessarily be written by the same developer so it may not be reliable to do that. If I’m willing to write a little more code on the client, I can iterate through the invocation list of the delegate (in this case, CheckDataSource) and fire each one separately, checking the value of the Cancel property after each one and deciding whether to continue. In VB: Dim o_InvocationList() As _ [Delegate] = _ o_FilterEvents.CheckDataSource. _ GetInvocationList() For Each o_Filter As AcmeModuleDelegate( _ Of CheckDataSourceEventArgs) In o_InvocationList If o_Filter IsNot Nothing Then Dim o_EventArgs As New _ CheckDataSourceEventArgs( s_Source) o_Filter.Invoke(o_EventArgs) If o_EventArgs.Cancel Then b_Cancel = True Exit For End If End If Next In C#: Delegate[] o_InvocationList = o_FilterEvents.CheckDataSource. GetInvocationList(); foreach ( AcmeModuleDelegate <CheckDataSourceEventArgs> o_Filter in o_InvocationList) { if (o_Filter != null) { CheckDataSourceEventArgs o_EventArgs = new CheckDataSourceEventArgs( s_Source); o_Filter.Invoke(o_EventArgs); if (o_EventArgs.Cancel) { b_Cancel = true; break; } } } In this technique, as soon as one module sets its e.Cancel property to true, I break out of the loop and stop further processing. At this point, in either of the two techniques, the b_Cancel variable will determine if I should continue processing all additional code. You can insert all additional extensibility points in either of the two methods: the one that calls all module events in one Invoke execution or the one that iterates through the invocation list of the corresponding delegate and invokes one event at a time. Extensibility modules are a great way to put multiple points of extensibility in your client and, at the same time, centralize how you write the extensibility plug-ins. You can choose to develop a class for each event you are going to tap into or you can group several together. If you’re going to choose the latter, you should do so because the interception code you’re placing into the various events is somehow logically related from one event to another. An example of this would be in writing a Profanity Filter. Such a filter may want to check for profanity at different points in your application. Since I created an extensibility point called CheckDataSource and another called PreProcessData, I can check for profanity at both of these points by writing one module class that taps into both of these events. The events will still be called from their appropriate extensibility points within the client, but they will be housed in one class, logically grouping them together. You can see the entire code of such a module in Listing 4. Conclusion These patterns can help you design and code applications that are easier and more elegant to enhance or modify. They also introduce a style of programming that’s based on the ability to interchange functionality easily. However, don’t feel that you have to spend too much time on deciding where to insert points of extensibility in your application-just keep it all in mind. As you design and develop applications, you will more than likely have points that will snap out at you. Try to resist over abstracting at the beginning and don’t be afraid to refactor into it later; but beware, once you get the hang of using these patterns, you will be addicted.	http://www.codemag.com/article/0801041	CC-MAIN-2016-40	refinedweb	6,524	52.6
Conventions for Recursive Makefiles and Directories Conventions for Recursive Makefiles and Directories This chapter includes: - Structure of a multiplatform source tree - Specifying options - Using the standard macros and include files - Advanced topics - Examples of creating Makefiles In this chapter, we'll take a look at the supplementary files used in the. Structure of a multiplatform source tree. Macros The example given above uses the LATE_DIRS macro. Here are the macros that you can place within a makefile: - EARLY_DIRS - LATE_DIRS - LIST - MAKEFILE - CHECKFORCE The EARLY_DIRS and LATE_DIRS macros: - VARIANT - CPU - OS. Directory levels.). Project level. Section level (optional) You use the section-level directory to contain the source base relevant to a part of the project. You can omit it if you don't need it; see “Collapsing unnecessary directory levels,” later in this chapter. OS level. CPU level. Variant level Finally, the variant level contains object, library, or executable files specific to a particular variant of the processor. For example, a MIPS processor could operate in big-endian or little-endian mode. In that case, we'd have to generate two different sets of output modules. On the other hand, an x86 processor is a little-endian machine only, so we need to build only one set of output modules. Specifying options file: - the last component is assigned to the VARIANT1 macro - the next previous component is assigned to the CPU macro - the next previous component is assigned to the OS macro - the next previous component is assigned to the SECTION macro - the next previous component is assigned to the PROJECT macro For example, if we have a pathname of /source/factory/robot_plc/driver/nto/ppc/o.be, then the macros are set as follows: The variant-level makefile. Recognized variant names You can combine variant names into a compound variant, using a period (.), dash (-), or slash (/) between the variants. The common makefiles are triggered by a number of distinguished variant names: - a - The image being built is an object library. - so - The image being built is a shared object. - dll - The image being built is a DLL; it's linked with the -Bsymbolic option (see ld in the Utilities Reference). If the compound variant doesn't include a, so, or dll, an executable is being built. - shared - Compile the object files for .so use, but don't create an actual shared object. You typically use this name in an a.shared variant to create a static link archive that can be linked into a shared object. - g - Compile and link the source with the debugging flag set. - be, le - Compile and link the source to generate big- (if be) or little- (if le) endian code. - gcc - Use the GCC (gcc) compiler to compile the source. If you don't specify a compiler, the makefiles provide a default. - o - This is the NULL variant name. It's used when building an image that doesn't really have any variant components to it (e.g. an executable for an x86 CPU, which doesn't support bi-endian operation).: - VARIANT_so - VARIANT_403 - VARIANT_be. Using the standard macros and include files We've described the pieces you'll provide when building your system, including the common.mk include file. Now let's look at some other include files: We'll also look at some of the macros that these files set or use. The qconfig.mk include file Since the common makefiles have a lot of defaults based on the names of various directories, you can simplify your life enormously in the common.mk include file if you choose your directory names to match what the common makefiles want. For example, if the name of the project directory is the same as the name of the image, you don't have to set the NAME macro in common.mk. The prototypical common.mk file looks like this: ifndef QCONFIG QCONFIG=qconfig.mk endif include $(QCONFIG) # Preset make macros go here include $(MKFILES_ROOT)/qtargets.mk # Post-set make macros go here The qconfig.mk include file provides the root paths to various install, and usage trees on the system, along with macros that define the compilers and some utility commands that the makefiles use. The purpose of the qconfig.mk include file is to let you tailor the root directories, compilers, and commands used at your site, if they differ from the standard ones that we use and ship. Therefore, nothing in a project's makefiles should refer to a compiler name, absolute path, or command name directly. Always use the qconfig.mk macros. The qconfig.mk file resides in $QNX_TARGET/usr/include/mk as qconf-os.mk (where os is the host OS, e.g. nto, qnx4, linux, win32), which is a symbolic link from the place where make wants to find it (namely $QNX_TARGET/usr/include/qconfig.mk). You can override the location of the include file by specifying a value for the QCONFIG macro. If you wish to override the values of some of the macros defined in qconfig.mk without modifying the contents of the file, set the QCONF_OVERRIDE environment variable (or make macro) to be the name of a file to include at the end of the main qconfig.mk file. Preset macros. Postset macros Following the inclusion of qtargets.mk, you can override or (more likely) add to the macros set by qtargets.mk. Do this in the area tagged as “Post-set make macros go here” in the sample above. qconfig.mk macros Here's a summary of the macros available from qconfig.mk: - CP_HOST - Copy files from one spot to another. - LN_HOST - Create a symbolic link from one file to another. - RM_HOST - Remove files from the filesystem. - TOUCH_HOST - Update a file's access and modification times. - PWD_HOST - Print the full path of the current working directory. - CL_which - Compile and link. - CC_which - Compile C/C++ source to an object file. - AS_which - Assemble something to an object file. - AR_which - Generate an object file library (archive). - LR_which - Link a list of objects/libraries to a relocatable object file. - LD_which - Link a list of objects/libraries to a executable/shared object. - UM_which - Add a usage message to an executable. compilation tool - a Neutrino target system - an x86 platform - the GNU GCC compiler: - CLPOST_which - CCPOST_which - ASPOST_which - ARPOST_which - LRPOST_which - LDPOST_which - UMPOST_which qrules.mk include file The qrules.mk include file defines the macros used for compiling. You can inspect — and in some cases, also set — the following macros when you use qrules.mk. Since the qtargets.mk file includes qrules.mk, these are available there as well. Don't modify those that are marked “(read-only).” - VARIANT_LIST (read-only) - A space-separated list of the variant names macro. Useful with the $(filter ...) make function for picking out individual variant names. - CPU - The name of the target CPU. Defaults to the name of the next directory up with all parent directories stripped off. - CPU_ROOT (read-only) - The full pathname of the directory tree up to and including the OS level. - OS - The name of the target OS. Defaults to the name of the directory two levels up with all parent directories stripped off. - OS_ROOT (read-only) - The full pathname of the directory tree up to and including the OS level. - SECTION - The name of the section. This is set only if there's a section level in the tree. - SECTION_ROOT (read-only) - The full pathname of the directory tree up to and including the section level. - PROJECT (read-only) - The basename() of the directory containing the common.mk file. - PROJECT_ROOT (read-only) - The full pathname of the directory tree up to and including the project level. - PRODUCT (read-only) - The basename() of the directory above the project level. - PRODUCT_ROOT (read-only) - The full pathname of the directory tree up to and including the product level. - NAME - The basename() of the executable or library being built. Defaults to $(PROJECT). - SRCVPATH - A space-separated list of directories to search for source files. Defaults to all the directories from the current working directory up to and including the project root directory. You'd almost never want to set this; use EXTRA_SRCVPATH to add paths instead. - EXTRA_SRCVPATH - Added to the end of SRCVPATH. Defaults to none. - INCVPATH - A space-separated list of directories to search for include files. Defaults to $(SRCVPATH) plus $(USE_ROOT_INCLUDE). You'd almost never want to set this; use EXTRA_INCVPATH to add paths instead. - EXTRA_INCVPATH - Added to INCVPATH just before the $(USE_ROOT_INCLUDE). Default is none. - LIBVPATH - A space-separated list of directories to search for library files. Defaults to: . $(INSTALL_ROOT_support)/$(OS)/$(CPUDIR)/lib $(USE_ROOT_LIB). You'll almost never want to use this; use EXTRA_LIBVPATH to add paths instead. - EXTRA_LIBVPATH - Added to LIBVPATH just before $(INSTALL_ROOT_support)/$(OS)/$(CPUDIR)/lib. Default is none. - DEFFILE - The name of an assembler define file created by mkasmoff. Default is none. - SRCS - A space-separated list of source files to be compiled. Defaults to all .s, .S, .c, and .cc files in SRCVPATH. - EXCLUDE_OBJS - A space-separated list of object files not to be included in the link/archive step. Defaults to none. - EXTRA_OBJS - A space-separated list of object files to be added to the link/archive step even though they don't have corresponding source files (or have been excluded by EXCLUDE_OBJS). Default is none. - OBJPREF_object, OBJPOST_object - Options to add before or after the specified object: OBJPREF_object = options OBJPOST_object = options The options string is inserted verbatim. Here's an example: OBJPREF_libc_cut.a = -Wl,--whole-archive OBJPOST_libc_cut.a = -Wl,--no-whole-archive - LIBS - A space-separated list of library stems to be included in the link. Default is none. - LIBPREF_library, LIBPOST_library - Options to add before or after the specified library: LIBPREF_library = options LIBPOST_library = options The options string is inserted verbatim. You can use these macros to link some libraries statically and others dynamically. For example, here's how to bind libmystat.a and libmydyn.so to the same program: LIBS += mystat mydyn LIBPREF_mystat = -Bstatic LIBPOST_mystat = -Bdynamic This places the -Bstatic option just before -lmystat, and -Bdynamic right after it, so that only that library is linked statically. - CCFLAGS - Flags to add to the C compiler command line. - ASFLAGS - Flags to add to the assembler command line. - LDFLAGS - Flags to add to the linker command line. - VFLAG_which - Flags to add to the command line for C compiles, assemblies, and links; see below. - CCVFLAG_which - Flags to add to C compiles; see below. - ASVFLAG_which - Flags to add to assemblies; see below. - LDVFLAG_which - Flags to add to links; see below. - OPTIMIZE_TYPE - The optimization type; one of: - OPTIMIZE_TYPE=TIME — optimize for execution speed - OPTIMIZE_TYPE=SIZE — optimize for executable size (the default) - OPTIMIZE_TYPE=NONE — turn off optimization Note that for the VFLAG_which, CCVFLAG_which, ASVFLAG_which, and LDVFLAG_which macros, the which part is the name of a variant. This combined macro is passed to the appropriate command line. For example, if there were a variant called “403,” then the macro VFLAG_403 would be passed to the C compiler, assembler, and linker. The qtargets.mk include file The qtargets.mk include file has the linking and installation rules. You can inspect and/or set the following macros when you use qtargets.mk: - INSTALLDIR - The subdirectory where the executable or library is to be installed. Defaults to bin for executables, and lib/dll for DLLs. If you set it to /dev/null, then no installation is done. - USEFILE - The file containing the usage message for the application. Defaults to none for archives and shared objects and to $(PROJECT_ROOT)/$(NAME).use for executables. The application-specific makefile can set the macro to a null string, in which case nothing is added to the executable. - LINKS - A space-separated list of symbolic link names that are aliases for the image being installed. They're placed in the same directory as the image. The default is none. - PRE_TARGET, POST_TARGET - Extra steps to do before/after the main target. - PRE_CLEAN, POST_CLEAN - Extra steps to do before/after the clean target. - PRE_ICLEAN, POST_ICLEAN - Extra steps to do before/after the iclean target. - PRE_HINSTALL, POST_HINSTALL - Extra steps to do before/after the hinstall target. - PRE_CINSTALL, POST_CINSTALL - Extra steps to do before/after the cinstall target. - PRE_INSTALL, POST_INSTALL - Extra steps to do before/after the install target. - PRE_BUILD, POST_BUILD - Extra steps to do before/after building the image. - SO_VERSION - The SONAME version number to use when building a shared object (the default is 1). - PINFO - Information to go into the .pinfo file.. Advanced topics In this section, we'll discuss how to: - collapse unnecessary directory levels - perform partial builds - perform parallel builds - use GNU configure Collapsing unnecessary directory levels. Performing partial builds By: - recurse into only the specified tagged directories Or: - recurse into all of the directories except for the specified tagged ones: - LIST=CPU - CPULIST - EXCLUDE_CPULIST Performing parallel builds. More uses for LIST GNU configure it hasn't, build-cfg invokes the hook_preconfigure() function, then the project's configure, and then the hook_postconfigure() function. - If the configure has already been done, or we just did it successfully, build-cfg invokes the hook_premake(), then does a make -fMakefile, then hook_postmake(), then hook_pinfo(). If a function isn't defined in build-hooks, build-cfg doesn't bother trying to invoke it. Within the build-hooks script, the following variables are available: - SYSNAME - The host OS (e.g. nto, linux) that we're running on. This is automatically set by build-cfg, based on the results of uname. - TARGET_SYSNAME - The target OS (e.g. nto, win32) that we're going to be generating executables for. It's set automatically by build-cfg, based on the directory that you're in. - make_CC - This variable is used to set the CC make variable when we invoke make. This typically sets the compiler that make uses. It's set automatically by build-cfg, based on the directory that you're in. - make_opts - Any additional options that you want to pass to make (the default is ""). - make_cmds - The command goals passed to make (e.g. all). It's set automatically by build-cfg what you passed on the original make command line. - configure_opts - The list of options that should be passed to configure. The default is "", but --srcdir=.. is automatically added just before configure is called. hook_preconfigure() } hook_postconfigure().$$ } hook_premake() This function is invoked just before the make. You don't usually need it. hook_postmake() This function is invoked just after the make. We haven't found a use for this one yet, but included it for completeness. hook_pinfo() This function is invoked after hook_postmake(). Theoretically, we don't need this hook at all and we could do all its work in hook_postmake(), but we're keeping it separate in case we get fancier in the future. This function is responsible for generating all the .pinfo files in the project. It does this by invoking the gen_pinfo() function that's defined in build-cfg, which generates one .pinfo. The command line for gen_pinfo() is: gen_pinfo [-nsrc_name ] install_name install_dir pinfo_line... The arguments are: - src_name - The name of the pinfo file (minus the .pinfo suffix). If it's not specified, gen_pinfo() uses install_name. - install_name - The basename of the executable when it's installed. - install_dir - The directory the executable should be installed in. If it doesn't begin with a /, the target CPU directory is prepended to it. For example, if install_dir is usr/bin and you're generating an x86 executable, the true installation directory is /x86/usr/bin. - pinfo_line - Any additional pinfo lines that you want to add. You can repeat this argument as many times as required. Favorites include: - DESCRIPTION="This executable performs no useful purpose" - SYMLINK=foobar.so Here's an example from the nasm project: function hook_pinfo { gen_pinfo nasm usr/bin LIC=NASM DESCRIPTION="Netwide X86 Assembler" gen_pinfo ndisasm usr/bin LIC=NASM DESCRIPTION="Netwide X86 Disassembler" } Examples of creating Makefiles As mentioned earlier, if you use our directory structure, you should use the addvariant command to create it. This section gives some examples of creating Makefiles for a single application, as well as for a library and an application. A single: - Since x86 only has little endian-ness, it doesn't have an extension. - If there's a choice, the variant level directory name would have a .be or .le at the end (e.g. o.le). - If we're building shared libraries, we'd replace the o variant with a so variant. - If we were building shared objects that aren't meant to be linked directly with applications, we'd use a dll variant. - If we were building static libraries, we'd use an a variant.. A library and an application	http://www.qnx.com/developers/docs/6.4.1/neutrino/prog/make_convent.html	CC-MAIN-2014-15	refinedweb	2,761	58.79
Heyyy everyone! xD here is a tutorial for adding the time of multiple cities in your programs, using datetime and pytz. I have included two versions; one of them where you have to manually change it in the code, and another where you ask the user! 1st method: from datetime import datetime import pytz tz_city = pytz.timezone('country/city') # replace 'country' and 'city' with your choice # for cities with two words, add an underscore in between them datetime_city = datetime.now(tz_city) # prints the time, in hours, minutes, and seconds. print("Time:", datetime_city.strftime("%H:%M:%S")) 2nd method the second method is a bit more complex, its the repl attached below. there are many comments to guide you. it includes: - a input to ask the user the continent/city of their choice - tells you if its PMor AM - has an error message if the user puts a typo/not existing/etc. (using tryand except) anyways, if you have any questions, please ask them and I will try to answer them. feel free to comment suggestions, tips, chatter, etc. And if it helped you, Upvoting is Caring! ;) Have a super-duper day! disclaimer: not all cities are displayed, but many are (major cities, capitals, high population, etc.) and oceania doesnt work :/ also i didnt know of time.time(), but can it find the time of many different cities? @johnstev111 Incredible! Only 0.5~ seconds delay! well first of all, you can look at my code, the comments will tell you exactly what to do. then, you can try to incorporate it into one of your own projects. ;) @eddyth0420 Nice! I have never really needed time in my program, but now I might add it to my programs! Hey bookie! Nice post! I do have one small complaint though, could you calm down on the y's a tiny bit? Its a little troublesome when AllAwesome497's bot auto reports this for spam when you do that. Thanks in advance! (Also interesting use of datetime) AWESOME thanks! =) @BobTheTomatoPie	https://repl.it/talk/learn/How-To-Get-The-Time-alarm-clock-python/43965	CC-MAIN-2020-34	refinedweb	336	74.39
In this tutorial, you will learn to make a physics-based platform game in the quickest way possible with the World Construction Kit. Final Result Preview Let's take a look at the final result we will be working towards: It's a little wonky, but that can be fixed -- and wait until you see how quick and easy it was to make! Step 1: Download Download the Box2D Alchemy Port and WCK libraries. Get the source from github and for more information, see. Step 2: New FlashDevelop Project Click on 'Project' and select 'New Project' from the list. Select AS3 Project as your project template, name your project, point it to an empty directory and click OK. Locate the Box2D/WCK libraries that you downloaded in Step 1 and place the following folders in your new project's 'lib' folder: Box2D, Box2DAS, extras, gravity, misc, shapes, and wck. Click on 'Project' again and select Properties. Click on the 'Classpaths' tab and add your lib folder. Open Main.as in the source file and add the highlighted code. FlashDevelop should have auto-generated the rest. public class Main extends WCK { public function Main():void { if (stage) init(); else addEventListener(Event.ADDED_TO_STAGE, init); } private function init(e:Event = null):void { removeEventListener(Event.ADDED_TO_STAGE, init); // entry point } } Step 3: Set Up the Flash IDE Open Flash Professional. Press Ctrl+Shift+F12 to open Publish Settings. Click the Flash tab. Select the option 'Export SWC' ....and then click the Settings button next to the ActionScript 3.0 combobox. In the Source Path tab, click on the 'browse to path' icon and select your lib folder. Then click on the Library Path tab and select the 'browse to SWC' icon. Select the file lib/Box2DAS/Box2D.swc. Click OK in Advanced Actionscript 3 Settings and again on the Publish Settings window. Save your FLA in the \src\ folder of your FlashDevelop project (the same folder with Main.as). Finally, press Ctrl+F3 to open the document properties and set the Document Class to Main. Step 4: Your First World Object Start by using the rectangle tool to draw a rectangle on the stage. Convert the rectangle to a symbol by selecting it and pressing F8. Set the registration point to the center. Note: It is very important that you register all of the game symbols this way. Failure to do so will affect how your object responds to gravity and collisions. Click 'export for Actionscript' and set the Base Class to shapes.Box Step 5: Create the World This may seem counter-intuitive, that you made a world object before you made your world. You could do it either way, but you'll see that it's quicker to do it this way. Select your Static Box object on the stage and press F8. Just like you did with the Static Box, set the World's registration point to the center and check Export for ActionScript. Set the base class to wck.World Step 6: Define World Component Right click on your newly created World symbol in the library. Select "Component Definition..." In the Class field, type wck.World This is a major selling-point for the World Construction Kit. If you now click on the World object on the stage and open the properties panel by pressing Ctrl + F3, you can edit a bunch of the World component's inspectable properties under the heading 'Component Parameters'. Step 7: Define Static Object Component Ok, now we're going to do the same thing with our static object. Right click on your Static Box symbol in the library. Select "Component Definition..." In the Class field, type wck.BodyShape Open the properties panel by selecting the Static Box object on the stage and pressing Ctrl + F3. Scroll the Component Parameters window to the bottom and change the 'type' from dynamic to static. If you forget to do this, your static components (walls, floors, platforms) will become subject to gravity and fall off the screen at runtime. Step 8: Build the Floor and Walls Select your Static Object inside of the World. Copy and paste it a couple times. Select each instance of Static Object and, using 'Free Transform', stretch, skew, and move your static objects around to form walls and a floor. You do not need to keep the boundaries on the stage. Here is an example of one of my attempts: Clearly, 'being an artist' is not a prerequisite for this tutorial.. Step 9: Build Your Hero! What's a good platformer without a compelling protagonist? While inside of the World object, draw a rectangle. Feel free to get creative here. This is the best I was able to do: Convert your character to a symbol, but don't declare a Base Class just yet. Right click your new Hero symbol in the library. Select "Component Definition..." In the Class field, type wck.BodyShape Step 10: Create the Player Class Open FlashDevelop. Make sure your project is open. In the \src\ folder, make a new folder called 'View.' In 'View' create a new folder called 'Characters.' Right click 'View' and Add New Class. Name your class something like HeroCharacter.as and set the base class to shapes.Box. Your folder structure should now look like this: Step 11: Override the Create Method This is the entry point for adding functionality to your characters. Add the following code to our new class: public class HeroCharacter extends Box { private var contacts:ContactList; public override function create():void { reportBeginContact = true; reportEndContact = true; contacts = new ContactList(); contacts.listenTo(this); fixedRotation = true; listenWhileVisible(world, StepEvent.STEP, world_stepEventHandler, false, 0, true); listenWhileVisible(this, ContactEvent.BEGIN_CONTACT, this_beginContactHandler, false, 0, true); super.create(); } } By setting reportBeginContact and reportEndContact to true, we are setting properties on the BodyShape class. We are indicating that we would like the BodyShape to dispatch ContactEvents when collisions begin and when collisions end. We then instantiate a ContactList and ask it to " listenTo this". ContactList.listenTo(this) creates listeners for ContactEvent.BEGIN_CONTACT and ContactEvent.END_CONTACT. It then creates handlers for each that store the collision information. You can see all of this by putting your cursor on ContactList and pressing Ctrl+F4 in FlashDevelop. By setting fixedRotation to true, we ensure that our hero will not rotate forwards or backwards when colliding with objects. listenWhileVisible is another way of adding event listeners. We could have used addEventListener(StepEvent.STEP, parseInput, false, 0, true); but the added functionality here is that listenWhileVisible will remove the event listeners and designate them for garbage collection when the Entity has been removed from the game. For our purposes, listenWhileVisible is a more optimized version of addEventListener. Note: As with addEventListener, always use weak references so that unused objects are eligible for garbage collection. By using super.create() we call the create() method on BodyShape. This lets us extend the functionality of the create() method instead of replacing it. Step 12: Handle Player Input Let's start by creating our StepEvent handler for player input. private function world_stepEventHandler(e:StepEvent):void { } At every time interval, a StepEvent will be dispatched from the b2World class in Box2D. The default time step is .05 seconds. You can change the timeStep parameter easily by going back to Flash Professional and opening the World component parameters. Next, we will use the Input utility to determine what keys are currently being pressed by the user. private function world_stepEventHandler(e:StepEvent):void { var left:Boolean = Input.kd('LEFT'); var right:Boolean = Input.kd('RIGHT'); var jump:Boolean = Input.kp('UP'); } The Input.kd method can accept multiple arguments. So, if we wanted to let the user to be able to control the HeroCharacter with WASD and the spacebar, we could amend the code as follows: private function world_stepEventHandler(e:StepEvent):void { var left:Boolean = Input.kd('LEFT', 'A'); var right:Boolean = Input.kd('RIGHT', 'D'); var jump:Boolean = Input.kp('UP', ' ', 'W'); } Input.kd() listens for when a key is down, while Input.kp() listens for the instant a key is pressed. Step 13: Apply Impulse to Move the Player When impulse is applied to a rigid body, the momentum of the body is changed. Momentum is the product of mass and velocity. So when we want to change the velocity (speed and direction) of our player, we will use a method on b2body called ApplyImpulse(). private function world_stepEventHandler(e:StepEvent):void { var left:Boolean = Input.kd('LEFT', 'A'); var right:Boolean = Input.kd('RIGHT', 'D'); var jump:Boolean = Input.kp('UP', ' ', 'W'); if (jump) { b2body.ApplyImpulse(new V2(0, -2), b2body.GetWorldCenter()); } else if(left) { b2body.ApplyImpulse(new V2(-2, 0), b2body.GetWorldCenter()); } else if(right) { b2body.ApplyImpulse(new V2(2, 0), b2body.GetWorldCenter()); } } ApplyImpulse() accepts two parameters: the world impulse vector and the point of application of the impulse. For now, we'll pass a new 2D vector as the first parameter for jumping, moving left and right (we'll have to make an adjustment to how we handle jumping a little later). The second parameter for each ApplyImpulse method is b2body.GetWorldCenter(). This method returns the world position of the center mass of our hero. This is important because ApplyImpulse will change our hero's angular velocity if it doesn't act upon his center mass (this is also why we used center registration on the hero in Flash). Step 14: Deal with Normal Force Go back into Flash Professional and set the Hero symbol's Class to "view.characters.HeroCharacter" and leave the Base Class blank. Next, set the instance name of your Hero instance to 'hero.' In the component parameters of the World component, deselect 'allowDragging' and select 'scrolling.' This way, the user won't be able to drag your character around with the mouse and the camera will follow your player when he moves. Finally, in the 'focusOn' field, type in 'hero,' your Hero's instance name. Press Ctrl+Enter to test the movie. You'll notice that you can move your character around by pressing left and right and can jump with space. But if you keep pressing space, you will keep jumping up indefinitely. The reason we can't keep jumping up indefinitely is that once we're airborne, there is nothing for our feet to push on to thrust us up. There is no equal force at our feet pushing back. When we are planted firmly on the ground, the force that aids us in jumping upward and keeps us from falling through the floor is called normal force. What we need to do is determine what the normal force is on our players feet. If there is no normal force, then he cannot take a jump. We'll do that by making use of our ContactList. Go back into FlashDevelop. Let's amend our step event handler once more: private function world_stepEventHandler(e:StepEvent ):void { var manifold:b2WorldManifold = null; if(!contacts.isEmpty()) { manifold = getNormalForce(); } var left:Boolean = Input.kd('LEFT', 'A'); var right:Boolean = Input.kd('RIGHT', 'D'); var jump:Boolean = Input.kp('UP', ' ', 'W'); if (jump && manifold) { var v:V2 = manifold.normal.multiplyN( -3); b2body.ApplyImpulse(v, b2body.GetWorldCenter()); } else if(left) { b2body.ApplyImpulse(new V2(-.5, 0), b2body.GetWorldCenter()); } else if(right) { b2body.ApplyImpulse(new V2(.5, 0), b2body.GetWorldCenter()); } } We'll write the code for the getNormalForce() method in just a second. What we want to do here is look for contacts (is our player touching anything?) get a manifold describing where our player is touching a contact (on the side or bottom) and accelerate the player upward if he is making contact with the ground. If there are no contacts, our hero must be in mid-air. In that case, the manifold would be null and the player would be unable to jump. Now let's write the getNormalForce() method. private function getNormalForce():b2WorldManifold { var manifold:b2WorldManifold = null; contacts.forEach(function(keys:Array, contactEvent:ContactEvent) { var tempManifold:b2WorldManifold = contactEvent.getWorldManifold(); if (tempManifold.normal.y > 0) { tempManifold.normal = new V2(0, tempManifold.normal.y); manifold = tempManifold; } }); contacts.clean(); return manifold; } Before calling getNormalForce(), we check to see if our player is in contact with anything. If he isn't, then we know he is airborne. The whole reason this function exists is to prevent the player from taking a second jump off of a wall or the side of a platform. First we declare a local variable called manifold and set it to null. This is the parameter we will be returning. If the hero character is in contact with something on his right left or top (but not the ground) this function will return a null manifold. Using the method contacts.forEach(), we can check each ContactEvent in our ContactList. All ContactEvents have a worldManifold property. So we create another local variable called tempManifold and set it to the value returned by each contactEvent.GetWorldManifold. Next, we check to see if temp.normal.y is greater than zero. Here we are asking, is there y-axis normal force? If the hero is on the ground or a platform, we zero out any x-axis normal force. Failure to do this results in buggy jumping when the player is pushed up against a wall. Feel free to experiment with this. If you don't zero the x, the player gets a cool (yet unreliable) kind of Metroid wall-jump ability. Finally, clean the ContactList. We don't want to handle the same contacts more than once. Step 15: Add Coins Now that we have a protagonist that can run around and jump, let's add some items that he can pick up. Go back into Flash Professional, draw a circle or ellipse for a coin and convert it to a symbol. Set the Class and Base class as shown: Put as many instances of the Coin Class as you want on the Stage. In Component Parameters, I set each Coin's type to static so that they are unaffected by gravity and can float in place like in Mario, but it's up to you. Step 16: Handle Collisions With Coins Right now, the coins are immovable, static objects. We'd like to change that. Go back to FlashDevelop and open the HeroCharacter class. Add an event handler for collisions like this: private function this_beginContactHandler(e:ContactEvent):void { } This is the handler for the listener that we created in Step 11. Add the following code: private function this_beginContactHandler(e:ContactEvent):void { var coin:Coin = e.other.m_userData as Coin; if(coin) { coin.remove(); } } First we create a local var called coin that is the same type as the Coin Class you created in Flash. ContactEvent keeps track of the other Box2D fixture involved in the collision. If it is Coin, we remove it from the Stage, giving the illusion that it has been collected. Step 17: Keep Score Create a folder inside the \src\ directory called 'model'. Inside 'model' make a folder called 'scoreboard' and make a new class called ScoreBoard that extends EventDispatcher. Since we only want to ever have one instance of the scoreboard around at one time, we're going to follow the Singleton design pattern. There was a Quick Tip about the Singleton pattern on Activetuts+ earlier this year if you want a reference. Write the following code in the ScoreBoard Class: package model.scoreboard { import flash.errors.IllegalOperationError; import flash.events.Event; import flash.events.EventDispatcher; public class ScoreKeeper extends EventDispatcher { private static var _instance:ScoreKeeper; public function ScoreKeeper() { if (_instance != null) { throw new IllegalOperationError("Use ScoreBoard.getInstance() to get a reference to the Singleton ScoreKeeper."); } else { initialize(); } } private function initialize():void { } public static function getInstance():ScoreKeeper { if (_instance == null) _instance = new ScoreKeeper(); return _instance; } } } This is the Singleton pattern. We expect any Class that wants to access the ScoreKeeper to use the static function getInstance(). If an instance already exists and someone (another developer on your team, for example) tries to instantiate the ScoreKeeper through its constructor, they will receive our error message telling them that the ScoreKeeper should only be accessed through getInstance(). The ScoreKeeper extends EventDispatcher so that it can dispatch Events when the score changes. We will build a score board as a view component that will subscribe to the ScoreKeeper events. Now we need the ScoreKeeper to actually begin keeping score. We need a variable to hold the score, a method that increments the score, a getter for the score so that other classes can access it and a public static const to store our Event type. package model.scoreboard { import flash.errors.IllegalOperationError; import flash.events.Event; import flash.events.EventDispatcher; public class ScoreKeeper extends EventDispatcher { public static const SCORE_CHANGED:String = "SCORE_CHANGED"; private var _score:uint; private static var _instance:ScoreKeeper; public function ScoreKeeper() { if (_instance != null) { throw new IllegalOperationError("Use ScoreBoard.getInstance() to get a reference to the Singleton ScoreKeeper."); } else { initialize(); } } private function initialize():void { _score = 0; } public function incrementScore():void { _score++; dispatchEvent(new Event("SCORE_CHANGED")); } public static function getInstance():ScoreKeeper { if (_instance == null) _instance = new ScoreKeeper(); return _instance; } public function get score():uint { return _score; } } } And that's all we need for our ScoreKeeper. Now let's make a view component to display the score number. Go into Flash and on the stage (not inside of the World symbol) draw out a scoreboard. The only important thing here is that you use the Text Tool to draw a TextField with the instance name ' score'. Convert the TextField to a movie clip symbol called ScoreBoard. Back in FlashDevelop, in the world folder, create a Class called 'ScoreDisplay' that extends MovieClip. All we need to do here is get an instance of ScoreKeeper and subscribe to its events. It should look like this: package view.world { import flash.display.MovieClip; import flash.events.Event; import flash.text.TextField; import model.scoreboard.ScoreKeeper; public class ScoreDisplay extends MovieClip { private var _scoreKeeper:ScoreKeeper = ScoreKeeper.getInstance(); public function ScoreDisplay() { this.score.text = "0"; _scoreKeeper.addEventListener(ScoreKeeper.SCORE_CHANGED, scoreBoard_ScoreChangedHandler, false, 0, true); } private function scoreBoard_ScoreChangedHandler(e:Event):void { this.score.text = _scoreKeeper.score.toString(); } } } Go back to Flash and open the properties of the ScoreBoard symbol in the library. Change the Class to view.world.ScoreDisplay. You have one last step. Go back to the HeroCharacter class and add two lines of code: private function this_beginContactHandler(e:ContactEvent):void { var coin:Coin = e.other.m_userData as Coin; if(coin) { coin.remove(); scoreBoard.incrementScore(); } } public class HeroCharacter extends Box { private var contacts:ContactList; private var scoreKeeper:ScoreKeeper = ScoreKeeper.getInstance(); Step 18: Add Static Platforms Go into Flash Professsional and place an instance of StaticBox (the same one we used to make walls and the floor) inside the World instance. Make sure that you set its type to static in the Component Parameters and that the platform is low enough that your player can jump to it. Step 19: Add Suspended Platforms With Box2D Joints WCK makes creating swinging platforms very easy. We can do the whole thing in the Flash IDE without writing any code. Start by drawing a circle. Convert the circle to a symbol called Joint and set the Base Class to wck.Joint. Next, right-click the Joint symbol in the library and go to Component Definition. Set the Class as wck.Joint. In the Properties panel, set the instance name as anchor and in Component Parameters, change the type to Revolute. This is the joint that will give our platform a pendulum action. Draw a platform with the Rectangle tool. Select it and convert it to a symbol. Set the Base Class to extras.Platform. Right click on the symbol in the library and in Component Definition, set the Class to extras.Platform. Drag out two more instances of the Joint Class into World and place each one at either end of the Platform. The layout should look like this: For each new Joint instance, go into Component Parameters and change type to ' Distance' and in the target2Name field write ' anchor'. Test your movie and you should have a swinging platform. Step 20: Add Enemies In FlashDevelop, add a new class to the \characters\ folder called EnemyCharacter. Here's the code we're going to write (this will look very familiar): package view.characters { import Box2DAS.Common.V2; import Box2DAS.Dynamics.ContactEvent; import Box2DAS.Dynamics.StepEvent; import shapes.Box; import wck.ContactList; public class EnemyCharacter extends Box { private var contacts:ContactList; private var left:Boolean = true; private var right:Boolean; public override function create():void { fixedRotation = true; reportBeginContact = true; super.create(); contacts = new ContactList(); contacts.listenTo(this); listenWhileVisible(world, StepEvent.STEP, world_stepEventHandler, false, 0, true); listenWhileVisible(this, ContactEvent.BEGIN_CONTACT, this_beginContactHandler, false, 0, true); } private function world_stepEventHandler(e:StepEvent ):void { if(left) { b2body.ApplyImpulse(new V2(-.1, 0), b2body.GetWorldCenter()); } else if(right) { b2body.ApplyImpulse(new V2(.1, 0), b2body.GetWorldCenter()); } } private function this_beginContactHandler(e:ContactEvent):void { var wall:StaticBox = e.other.m_userData as StaticBox; if(wall) { left = !left; right = !right; } } } } The only new thing here is that every time the object collides with a wall, it changes direction. And every step event, the enemy character is going to have an impulse applied in the direction he is facing. Go back into Flash and draw an enemy character, and convert it to a symbol with the Base Class set to view.characters.EnemyCharacter and Class set to Enemy. The last thing we need to do is handle contact between the player character and the enemy character. In the HeroCharacter class, add the following code: private function this_beginContactHandler(e:ContactEvent):void { var coin:Coin = e.other.m_userData as Coin; trace(coin); if(coin) { coin.remove(); scoreKeeper.incrementScore(); } else { var enemy:EnemyCharacter = e.other.m_userData as EnemyCharacter; if (enemy) { var tempManifold:b2WorldManifold = e.getWorldManifold(); if (tempManifold.normal.y > 0) { Util.addChildAtPosOf(world, new BadGuyFX(), enemy); enemy.remove(); } } } } If our hero makes contact with something and it isn't a coin, we will check to see if it is the EnemyCharacter. If it is, we'll check the manifold of the ContactEvent to determine if we hit the bad guy on top or on the side. If we jumped on top of him, he will be removed from the stage. I wanted to add an animation of the EnemyCharacter getting squashed so in Flash I made a movie clip with a timeline animation of the enemy getting crushed. I set the Base Class of that BadGuyFX object to misc.FX, a Class in the WCK library that plays through its own timeline animation once and then sets itself to null. Then I added it to the Stage with the Util method addChildAtPosOf(). The animation makes the enemy removal not seem so sudden. Conclusion Now that you have a working prototype of a platformer, I encourage you to keep exploring what WCK has to offer. I especially recommend playing around in the Component Parameters of your game objects. This is a really fun and quick way to alter the physics of your game world without writing any code. I hope you enjoyed this tutorial! Thanks for reading! Envato Tuts+ tutorials are translated into other languages by our community members—you can be involved too!Translate this postPowered by	http://code.tutsplus.com/tutorials/build-a-physics-based-platformer-in-under-an-hour--active-7324	CC-MAIN-2016-07	refinedweb	3,867	59.5
Matplotlib has a default color cycle for all the graphs and plots, however, in order to draw plots with multiple color cycles, we can use the cycler property of Matplotlib. It is used to plot repetitive patterns for the axis. First, we will use the Object Oriented APIs such as pyplot to plot the specific visualization. from cycler import cycler import numpy as np from matplotlib.backends.backend_agg import FigureCanvasAgg as FigureCanvas from matplotlib.figure import Figure from IPython.core.display import display In this example, we will create two objects which will repeat the cycle after every four objects. Thus, after creating two objects, the last two will be the repeat of the first two objects. fig = Figure() FigureCanvas(fig) Set the axis with facecolor, alpha, and edgecolor, fig.set(facecolor='grey', alpha=0.2, edgecolor='m') ax = fig.add_subplot(111) Setting the data for plotting the graph, x = np.array([0.4, 0.8, 1.2, 1.6, 2.0]) y = [1, 6, 6, 1, 0] Now define the custom cycler for the color and hatch attributes and set it to the axis, custom_cycler = cycler('color', ['g', 'blue', 'y', 'c']) + \ cycler('hatch', ['+*', 'xx', '+x', '+O.']) ax.set_prop_cycle(custom_cycler) Plot the graph for the six objects, ax.fill(x+1, y) ax.fill(x+2, y) ax.fill(x+3, y) ax.fill(x+4, y) ax.fill(x+5, y) ax.fill(x+6, y) Display the plot, display(fig)	https://www.tutorialspoint.com/how-to-plot-with-multiple-color-cycle-using-cycler-property-in-matplotlib	CC-MAIN-2021-10	refinedweb	242	52.46
trace Pint information about raw branch tracing data. maint btrace packet-history Print the raw branch trace packets that are used to compute the execution history for the ‘record btrace’ command. Both the information and the format in which it is printed depend on the btrace recording format. bts For the BTS recording format, print a list of blocks of sequential code. For each block, the following information is printed: Newer blocks have higher numbers. The oldest block has number zero. pt For the Intel Processor Trace recording format, print a list of Intel Processor Trace packets. For each packet, the following information is printed: Newer packets have higher numbers. The oldest packet has number zero. The packet’s offset in the trace stream. maint btrace clear-packet-history Discards the cached packet history printed by the ‘maint btrace packet-history’ command. The history will be computed again when needed. maint btrace clear Discard the branch trace data. The data will be fetched anew and the branch trace will be recomputed when needed. This implicitly truncates the branch trace to a single branch trace buffer. When updating branch trace incrementally, the branch trace available to GDB may be bigger than a single branch trace buffer. maint set btrace pt skip-pad maint show btrace pt skip-pad Control whether GDB will skip PAD packets when computing the packet history. set catch-demangler-crashes [on\|off] maint show catch-demangler-crashes Control whether GDB should attempt to catch crashes in the symbol name demangler. The default is to attempt to catch crashes. If enabled, the first time a crash is caught, a core file is created, the offending symbol is displayed and the user is presented with the option to terminate the current session. maint cplus first_component name Print the first C++ class/namespace component of name. maint cplus namespace Print the list of possible C++ namespaces.] maint demangler-warning [message-text] Cause GDB to call the internal function internal_error, internal_warning or demangler_warning and hence behave as though an internal problem has been detected. In addition to reporting the internal problem, these functions give the user the opportunity to either quit GDB or (for internal_error and internal_warning) maint set demangler-warning action [ask\|yes\|no] maint show demangler. Note that there is no corefile option for demangler-warning: demangler warnings always create a core file and this cannot be disabled. [-single-feature] [file] Print the target description (see Target Descriptions) as a C source file. By default, the target description is for the current target, but if the optional argument file is provided, that file is used to produce the description. The file should be an XML document, of the form described in Target Description Format. The created source file is built into GDB when GDB is built again. This command is used by developers after they add or modify XML target descriptions. When the optional flag ‘-single-feature’ is provided then the target description being processed (either the default, or from file) must only contain a single feature. The source file produced is different in this case. maint print xml-tdesc [file] Print the target description (see Target Descriptions) as an XML file. By default print the target description for the current target, but if the optional argument file is provided, then that file is read in by GDB and then used to produce the description. The file should be an XML document, of the form described in Target Description Format. maint check xml-descriptions dir Check that the target descriptions dynamically created by GDB equal the descriptions created from XML files found in dir.. maint print core-file-backed-mappings Print the file-backed mappings which were loaded from a core file note. This output represents state internal to GDB and should be similar to the mappings displayed by the info proc mappings command.xa8206d8: id={stack=0xbfffe734,code=0xbfffe73f,!special}, ptid=process 9353 maint flush register-cache flushregs Flush the contents of the register cache and as a consequence the frame cache. This command is useful when debugging issues related to register fetching, or frame unwinding. The command flushregs is deprecated in favor of maint flush user-registers List all currently available user registers. User registers typically provide alternate names for actual hardware registers. They include the four “standard” registers $fp, $pc, $sp, and $ps. See standard registers. User registers can be used in expressions in the same way as the canonical register names, but only the latter are listed by the info registers and maint print registers commands. selftest [filter] Run any self tests that were compiled in to GDB. This will print a message showing how many tests were run, and how many failed. If a filter is passed, only the tests with filter in their name will by ran. maint info selftests List the selftests compiled in to GDB. maint set dwarf always-disassemble maint show dwarf max-cache-age maint show dwarf max-cache-age Control the DWARF compilation unit cache. In object files with inter-compilation-unit references, such as those produced by the GCC option ‘-feliminate-dwarf2-dups’, the DWARF dwarf unwinders maint show dwarf unwinders Control use of the DWARF frame unwinders. Many targets that support DWARF debugging use GDB’s DWARF frame unwinders to build the backtrace. Many of these targets will also have a second mechanism for building the backtrace for use in cases where DWARF information is not available, this second mechanism is often an analysis of a function’s prologue. In order to extend testing coverage of the second level stack unwinding mechanisms it is helpful to be able to disable the DWARF stack unwinders, this can be done with this switch. In normal use of GDB disabling the DWARF unwinders is not advisable, there are cases that are better handled through DWARF than prologue analysis, and the debug experience is likely to be better with the DWARF frame unwinders enabled. If DWARF frame unwinders are not supported for a particular target architecture, then enabling this flag does not cause them to be used. maint set worker-threads maint show worker-threads Control the number of worker threads that may be used by GDB. On capable hosts, GDB may use multiple threads to speed up certain CPU-intensive operations, such as demangling symbol names. While the number of threads used by GDB may vary, this command can be used to set an upper bound on this number. The default is unlimited, which lets GDB choose a reasonable number. Note that this only controls worker threads started by GDB itself; libraries used by GDB may start threads of their own. target-non-stop maint show target-non-stop This controls whether GDB targets always operate in non-stop mode even if set non-stop is off (see Non-Stop Mode). The default is auto, meaning non-stop mode is enabled if supported by the target. maint set target-non-stop auto This is the default mode. GDB controls the target in non-stop mode if the target supports it. maint set target-non-stop on GDB controls the target in non-stop mode even if the target does not indicate support. maint set target-non-stop off GDB does not control the target in non-stop mode even if the target supports it. maint set tui-resize-message maint show tui-resize-message Control whether GDB displays a message each time the terminal is resized when in TUI mode. The default is off, which means that GDB is silent during resizes. When on, GDB will display a message after a resize is completed; the message will include a number indicating how many times the terminal has been resized. This setting is intended for use by the test suite, where it would otherwise be difficult to determine when a resize and refresh has been completed. set check-libthread-db [on\|off] maint show check-libthread-db Control whether GDB should run integrity checks on inferior specific thread debugging libraries as they are loaded. The default is not to perform such checks. If any check fails GDB will unload the library and continue searching for a suitable candidate as described in set libthread-db-search-path. For more information about the tests, see maint check libthread-db.. maint test-options require-delimiter maint test-options unknown-is-error maint test-options unknown-is-operand These commands are used by the testsuite to validate the command options framework. The require-delimiter variant requires a double-dash delimiter to indicate end of options. The unknown-is-error and unknown-is-operand do not. The unknown-is-error variant throws an error on unknown option, while unknown-is-operand treats unknown options as the start of the command’s operands. When run, the commands output the result of the processed options. When completed, the commands store the internal result of completion in a variable exposed by the maint show test-options-completion-result command. maint show test-options-completion-result Shows the result of completing the maint test-options subcommands. This is used by the testsuite to validate completion support in the command options framework. maint set test-settings kind maint show test-settings kind These are representative commands for each kind of setting type GDB supports. They are used by the testsuite for exercising the settings infrastructure. maint with setting [value] [-- command] Like the with command, but works with maintenance set variables. This is used by the testsuite to exercise the with command’s infrastructure.]	https://sourceware.org/gdb/download/onlinedocs/gdb/Maintenance-Commands.html	CC-MAIN-2022-05	refinedweb	1,593	54.12
- Author: - davidchambers - Posted: - September 15, 2010 - Language: - Python - Version: - 1.2 - template-tags - Score: - 2 (after 2 ratings) This code is taken from a Stack Overflow answer by Will Hardy. Usage: {% collect var1 var2 'foo' 'bar' 5 as some_list %}. Sometimes one wishes to create a list on the fly within a template. Perhaps a collection needs to be passed to a template filter, but the collection cannot be created in the view since the values of one or more of its items are set in the template. A contrived example: {% with 5 as max %}{% with posts\|length as len %} {% for post in posts %} {% if forloop.counter <= max %} {% include 'excerpt.dhtml' %} {% endif %} {% endfor %} {% collect len max as limits %} <p>Displaying {{ limits\|minimum }} of {{ len }} post{{ posts\|pluralize }}.</p> {% endwith %}{% endwith %} The final line will state how many posts are displayed: something like "5 of 24" or "2 of 2". This particular problem can be solved in a number of other ways, some of which are more appropriate. Having a template tag that can create lists on the fly is potentially useful in quite a few situations, though. I don't know whether this need is common enough to warrant being in the core. If something like this is to be included one day, it'd be much nicer to overload the with tag than to introduce a new tag. {% with var1 var2 var3 as some_list %} reads well. # Please login first before commenting.	https://djangosnippets.org/snippets/2196/	CC-MAIN-2016-44	refinedweb	241	72.76
Post your Comment How to make a Chimpanzee face. How to make a Chimpanzee face. I have tried here to make a chimpanzee fame by the pen tool, It has so easy technique to make. To learn just follow some steps How to make an angry face, make an angry face, angry face How to make an angry face We have this example to teach you a simple method to make an angry face... as I have done here. This an angry face. Look make a alien face mask, make a alien face mask, alien face mask How to make a alien face mask Use this example to make a alien face mask, which... and Emboss and use both settings. You will get it. Make duplicate layer How to change the face, change the face How to change the face You have a chance to learn how to change the face of the person to another face. It has very simple technique to make this effect How to make a blooming Face. How to make a blooming Face. This tutorial will teach to a simple way to give a blooming face... to modify as I have opened here. Duplicate Layer of the Picture: Make How to design a face of the lady. Photoshop : How to design a face of the lady. How to design.... Face: Now we have to make face, So select pen tool (P key) and point your pen tool and make adjustment with selected detect selection tool (A key) as a face face Human face using applet programming - Applet Human face using applet programming import java.applet.; import... is rectangle change to arc on clicking...or it should turn into smilimg face........How do I proceed using ActionListener..........pls explain.... Create Human Face using Graphics Create Human Face using Graphics In this section, you will learn how to create human face using Graphics. A Graphics provides contexts that allow an application to draw onto components that are realized on various devices, as well as onto Human face using applet programming - Applet Human face using applet programming import java.awt.; import java.applet.*; public class HumanFace extends Applet{ private int mouseX, mouseY; private boolean mouseclicked = false; public void init(){ } public void make setup make setup i've made jbuilder application how could make autorun or jar executable for this application? waiting your answers soon make a program make a program GoodEmployee is defined who has ALL the following properties: He should be married. He should have 2 or less than 2 children. His middle name should start with "k" but not end with "e" The last name should have Make A website Make A website How expensive(hire someone) or hard would it be to create a website like this? I want to build a website where people can be users of the website with a small profile. Their is a point system (kinda like money make a webpage make a webpage I will provide you some basic requirements that you will be implementing over a small web page... Requirements: A web page having a title, heading, 3 text boxes, a checkbox, a submit button and a table Design Patterns Training in global IT industry aims to train IT professionals who would be able to make themselves robust to face the confronts in future needs. In order to achieve this target Make Money Make Money Can I make money from my web site by writing articles? Yes, You can make money from your web site. We are providing free information IT Training in India who would be able to make themselves robust to face the confronts in future... who would be able to make themselves robust to face the confronts in future needs... signifying a standard of teaching and course content is some how lacking. how to make this pattern??? how to make this pattern??? how to make following pattern in javascript How to make elements invisible ? How to make elements invisible ? How to make elements invisible how make ID - Ajax how make ID how make a ID in eyeball chat how to make exampage in jsp ? how to make exampage in jsp ? how to make a online exam page in jsp and servelet HTML make a thumbnail HTML make a thumbnail How do I make a thumbnail for my image make a picture a link make a picture a link hello, What is the way to make a picture a link? hii, This is the tab for image linking <A HREF=""><IMG SRC="image.gif"></A> IT Training in India make trial application make trial application Hello java master, i want to ask something about make java application trial in one month or two month. how to combine my application and give a trial application. what i must to do? Can you give me Post your Comment	http://www.roseindia.net/discussion/18031-How-to-make-a-Chimpanzee-face..html	CC-MAIN-2015-35	refinedweb	810	71.14
Technical Articles A step by step guide for creating an OData Service on HANA Calculation Views – XSODATA \| XSJS This blog is a short tutorial where you will learn how to publish the HANA Calculation View as an OData service. What we will be implementing - Creating a Simple Calculation View - Create an XS Project - Configuring xs access, to authenticate specific users or domains to access the exposed services. - Creating a Role and assigning select access to the Calculation view - Create XS OData - Adding a user in SQL Connections for the created Role. - Activating the user in SQL Connection Configuration - Using the XS Odata service Let’s start the tutorial! Step 1: Create a Calculation View - Open HANA Studio and open Development Perspective. - Then Go to Systems tab and add your system. - Expand System and go to Content Folder. - Create a new package with any name in my case “Elvin.ExposedCV” - Right Click and Create New Calculation View - Add VBAK to Aggregation Node and Select Some Columns. In the View Properties make Default Client = Cross Client. - Activate and See if data is coming in the View or not. Step 2: Create XSJS Project - Goto Project Explorer Tab. - Create a new XS Project. And Select your repository workspace. - Create Objects - Check the newly created project Step 3: Configure .xsaccess file There are many other things that we can configure in the below file like security, cache etc. It is currently out of scope for this blog so not covering here. { "exposed" : true, "authentication" : null, "anonymous_connection": "ELVIN.ExposedCV.XSSPandCVDemo::anonymous", "cors" : { "enabled":true, "allowMethods": ["GET","HEAD","OPTIONS","PUT"], "allowOrigin"["whitelist urls"], "maxAge":"3600" } } Authentication: can be Form/ Basic/ Null. Where Basic can be used to call the rest api (XS OData Service) from HCP cockpit destination. In the above script we have set authentication to null to give anonymous access to the users accessing the services from the allowed https origin. CORS is used to Allow Cross Origin Access. Here in the above script access to only one domain is allowed to call the API. Allowed Methods: These allows the API to send data to backend and retrieve from it. Exposed true specifies that the xsodata service will be exposed for use to outside world. anonymous_connection: Here I have specified the role name which is going to have access to my catalog objects. Note: This file can be activated only when all the steps from 4 to 7 are completed. Step 4: Create Role for accessing the catalog objects Right click on the project name in the project explorer and create a new file with name anonymous.hdbrole. Add the below code. Where you can replace Elvin.ExposedCV with your package name. We need this to give access to calculation view and stored procedure that we created above. Here the role name has to be the same as the full name of the file. To learn more about roles in HANA. You can see this blog. anonymous1.hdbrole role ELVIN.ExposedCV.XSSPandCVDemo::anonymous1{ catalog sql object "_SYS_BIC"."ELVIN.ExposedCV/EXPOSEVBAK":SELECT; catalog schema "_SYS_BI": EXECUTE; catalog analytic privilege: "_SYS_BI_CP_ALL"; } Here we are creating an anonymous role and giving him select access to the calculation views we want to expose as Rest APIs. A basic analytic privilege is also added which is required to be able to select the view from SYS_BI schema. Step 5: Create XS OData Create a services folder. Inside it create our fist file. services.xsodata : This is publishing our calculation view as an Odata service. service namespace "sap.hana.xstest" { "_SYS_BIC"."ELVIN.ExposedCV/EXPOSEVBAK" as "salesdata" key("VBELN"); } Step 6: Adding a user in SQL Connections for the created Role Create an anonymous.xssqlcc file. { "description" : "anonymous1", "role_for_auto_user" : "ELVIN.ExposedCV.XSSPandCVDemo::anonymous1" } When this file is activated an entry in the SQL_CONNECTIONS table in _SYS_XS is created. You need to have SELECT permission on this table to view its data. Step 7: Activating the user in SQL Connection Configuration Now you have to activate the above user in HANA XS Admin. For this, you need to have SQLCCAdministrator Role Then open HANA XS Admin from URL. {hostname}:{port}/sap/hana/xs/admin/ Select SQL Connection Configuration in filters and find anonymous file. Then click on apply search. You will see an anonymous role file. Then click on the anonymous.xssqlcc and then activate it. Once this is active. Go to HANA Studio and activate .xsaccess file. Step 8: Using the XS Odata service Right-click on xsodata service and Run AS XS service. It will open the URL in the internet explorer. Add “/salesdata” to the URL to check the data from the Calculation view. https://{hostname}:{port/ELVIN/ExposedCV/XSSPandCVDemo/services/services.xsodata/salesdata Conclusion You need to follow all the above steps to publish your HANA Calculation view to the OData service. Now you can add more to .xsaccess file to whitelist your endpoint URLs and also you can modify the roles and users’ access to make it a more secure connection. If you like it, I appreciate your rating for this blog post! 🙂 Very Helpful!! Superb Elvin !!! Hi Elvin, in 2020 I would suggest to use SAP Cloud Application Programming Model (CAP) which has support for Using Native SAP HANA Artifacts instead of XSOData. Best regards Gregor Hi Elvin, I am facing error in .xsaccess file on cors statement. Below is my code snippet. Please suggest. anonymous.hdbrole anonymous.xssqlcc These files are activated successfully. Hi @Sanketh Teegala, As the error description said. Your JSON is invalid. You have missed ":" after "allowOrigin". To validate your JSON you can use online tools like. BR, Elvin Baghele Thanks Elvin, it worked. Also want to highlight anonymous.hdbrole and anonymous.xssqlcc files should have role name as anonymous instead of anonymous1 otherwise it will activation error Error Message - Syntax error: role name "Himanshu.ExposedCV.XSSPandCVDemo::anonymous1" must be identical to the file name "Himanshu.ExposedCV.XSSPandCVDemo::anonymous" (without extension) Thanks, Sanketh As the error says in the above blog post, filename needs to be the same as the role name i.e anonymous1.hdbrole (corrected above). It was a typo error. In the .xsaccess file, you should mention the connection name, which is the xssqlcc file name. And we add the role information under the SQL connection configuration file (xssqlcc). Here our role name is annonymous1. Then we add the objects in hdbrole file; Objects which we want to give access to the anonymous connection. If you will notice the select statement and its output. You can see that the connection name is anonymous but role name is anonymous1. BR Elvin Baghele Hi Elvin, Nice blog. How to transport XS Project/ XS OData from Dev to other environments? I have created an XS Project, collected in a change id but I'm unable to assign the objects to a Delivery Unit. How to assign delivery units to these objects so that it can be transported. Appreciate any help! Thanks.	https://blogs.sap.com/2020/06/15/creating-odata-service-on-hana-calculation-views-xsodata-xsjs/	CC-MAIN-2022-40	refinedweb	1,159	59.19
#include <hallo.h> Anthony Towns wrote on Sat Aug 03, 2002 um 02:02:55PM: > > > I can give you some figures too: 33, 42, 978, 9.376. Numbers aren't any > > > value unless they're actually informative. > > I have to retain myself to not insult you. > > Imagine that. > > > I have followed all your advices, and the only thing you're telling me > > now is "please go play somewhere else". > > No, I'm telling you to _get a clue_. To be honest, I still have the impression that you use your get-a-clue statement just to make uncomfortable persons shut up. >? IMHO the working/candidate implementation could profit from your experience and be implemented much faster. The pool structure is ready now, "testing" control scripts exist as example. > That's the way it works. ...it works FOR YOU. You are the release manager. You are the only person with adequate experience and access to all required facilities. Who CAN do the same thing? No, you do not offer your help when somebody presents a concept not developed by you, you just tell anyone to make everything in his own. > > For this precise "problem" I don't have any idea of how we could > > experiment it to see if it brings anything to us. > > Monitor testing and update_excuses for a few months. Understand the > issues affecting all the packages that get delayed, and how possible > alternatives would've affected them. Look at the packages that weren't > affected by the delays and any RC bugs that were found, and see how > possible alternatives would've affected them. Make up a summary, so that > you can legitimately say "If we did things <this way>, then we'd have 10% > less delay on delayed packages, with possibly 5 additional RC bugs/month > making it into testing without being caught". Testing is not comparable with a working/candidate tree. Testing depends directly on Unstable. Did anyone consider automatical rebuilding of packages (against Testing) if they do not get into Testing because of dependencies on broken packages? > If you want something done any time soon, you make sure it doesn't affect > anyone. If you want something large done, make sure that it really, > demonstrably, is as important as you think. You're breaking both those > rules -- you want to affect just about everyone, and you're not even > able to say for sure that it's a particularly serious problem yourself. I personally would help Buxy implementing a such thing if someone would let us do it.)	https://lists.debian.org/debian-devel/2002/08/msg00128.html	CC-MAIN-2014-15	refinedweb	423	64.3
- Have this login page use create_login_url to redirect users to their openid login page. - Modify existing calls to create_login_url to instead send users to /_ah/login_required Here's a straightforward implementation of the /_ah/login handler: class OpenIdLoginHandler(webapp.RequestHandler): def get(self): continue_url = self.request.GET.get('continue') openid_url = self.request.GET.get('openid') if not openid_url: path = os.path.join(os.path.dirname(__file__), 'templates', 'login.html') self.response.out.write(template.render(path, {'continue': continue_url})) else: self.redirect(users.create_login_url(continue_url, None, openid_url)) This handler takes care of the first two changes we described earlier. First, we retrieve the 'continue' parameter (if it's provided), and the 'openid' parameter. If no openid parameter is provided, we show the login form. If an openid URL is provided, we pass both that and the continue URL to create_login_url, redirecting the user to the URL that function generates. Here's an excessively simplistic version of the login.html template: <html> <head> <title>Log in with OpenID</title> </head> <body> <h1>Log in with OpenID</h1> <form method="get" action="/_ah/login_required"> {% if continue %} <input type="text" name="continue" value="{{continue\|escape}}" /> {% endif %} <input type="text" name="openid" /> <input type="submit" value="Log In" /> </form> </body> </html> As you can see, all the page does is solicit the user's OpenID URL, and send it back, along with the already-provided continue URL, to the same handler we looked at earlier. Now that we've got basic OpenID support working, we should modify our app to send users to our own login page, instead of the default one for OpenID login with Google accounts. To do this, we'll define a simple function to take the place of create_login_url in these places: def create_openid_url(continue_url): continue_url = urlparse.urljoin(self.request.url, continue_url) return "/_ah/login?continue=%s" % urllib.quote(continue_url) Then, we replace any invocations of "users.create_login_url(something)" with "create_openid_url(something)" throughout our code, and we're done! Friendlier login pages The login page we demonstrated is pretty spartan. That's easily fixed, of course - you can style it as you would the rest of your site, and add descriptive text, and so forth. Worse, though, many users, when asked for their "openid URL" will simply look at you in puzzlement. What we need is a solution that avoids the need for most users to enter their URL themselves, while still allowing savvy users to do just that. Fortunately, there are a number of such solutions. One of them is clickpass. After signing in there and setting up an entry for your site, they'll provide you with code for a button that you can embed in your login page, and which allows users to choose from a number of well-known identity providers, including Hotmail, Yahoo!, Google, and Facebook, as well as entering their own URL. Once you've added your site in Clickpass, click on 'Log users in', and you'll be asked for a few details. Here's what they ask for, and how you should fill it out: There's one further advantage of using a system such as ClickPass's: You can embed the button widget on any and all pages of your site - which means your users don't have to visit your login page at all in the usual case: they'll go straight from your site to their provider's login page.Previous Post Next Post	http://blog.notdot.net/2010/05/Using-OpenID-authentication-on-App-Engine	CC-MAIN-2016-36	refinedweb	574	62.58
NAME vga_setmode - sets a video mode SYNOPSIS #include <vga.h> int vga_setmode(int mode); DESCRIPTION vga_setmode(int mode) selects the video mode given and clears the screen (if it was a graphics mode). Basically this should be the first action of your application after calling vga_init(3) and finding out which mode to use. Prior to exiting your application should call vga_setmode(TEXT).. Text mode TEXT(0) restores textmode and falls back to ordinary text console handling. All other calls switch to a graphics mode. You should set this mode prior to exiting an svgalib application. VGA compatible graphics modes In general, for all modes following, the first number is the amount of x pixels, the second the amount of y pixels, the third the number of colors, with shortcuts 32K, 64K, 16M, 16M4 for 32768, 65536, and 1677721. Those with 2 or more than 256 colors use fixed color mappings (either black and white or some RGB true/high color) the others make use of a color lookup table.) Basic SVGA modes These use linear 256 color memory layouts similar to G320x200x256. G640x480x256(10), G800x600x256(11), G1024x768x256(12), and G1280x1024x256(13) High color SVGA modes These also use linear memory layouts, but for 32K & 64K each pixel occupies two bytes and three for 16M. For 32K, each 16 bit word is divided into 555 bit portions refering to 5 bit red, green, blue part. The most significant bit is ignored by the card. For 64K the division is 565 allowing to specify green in a little bit more detail (Human eyes are more sensitive to green. People joke this is because our ancestors lived in trees where light was filtered through green leaves).) High resolutions with less color numbers. Memory layout is probably one nibble per pixel, two pixels per byte in a linear fashion where the most significant nibble is the left most pixel. G800x600x16(29), G1024x768x16(30), and G1280x1024x16(31) Hercules emulation mode Again check out the ordinary VGA literature for the memory layout. G720x348x2(32) 32-bit per pixel modes These are similar to 16M but each pixel uses four bytes. The first three are similar to 16M but the fourth is left empty and ignored by the VGA card (you can store own status there).) Some more resolutions It should by now be clear how the modes will look.. SEE ALSO svgalib(7), vgagl(7), libvga.config(5), vgatest(6), vga_hasmode(3), vga_init(3), vga_modeinfo(3), vga_getcurrentmode(3), vga_getdefault.	http://manpages.ubuntu.com/manpages/karmic/man3/vga_setmode.3.html	CC-MAIN-2014-42	refinedweb	414	62.78
0 Attached your will find my completed files, I only have one question about the parent class which is called GoeSolids it has to be a generic geometric solid and i dont think I did that quite right. will someone be able to help me fix it? import java.util.Scanner; import java.text.DecimalFormat; public class GeoSolids { int radius; int height; public GeoSolids (int radi, int h) { radius = radi; height = h; } public GeoSolids () { radius = 0; height = 0; } public void setRadius(int radi) { radius = radi; } public double getRadius() { return radius; } public void setHeight(int h) { height = h; } public double getHeight() { return height; } public String toString() { DecimalFormat fmt = new DecimalFormat("0.##"); String result = "The radius is " + fmt.format(radius) + "\nThe height is " + fmt.format(height); return result; } } Edited by mike_2000_17: Fixed formatting	https://www.daniweb.com/programming/software-development/threads/162770/geosolids	CC-MAIN-2017-13	refinedweb	131	54.12
Extract Class from Parameters ReSharper_ClassFromParameters This refactoring allows you to quickly create a new class or structure using parameters of a method. The selected parameters are converted into fields with properties, The method itself and all its usages are converted so that the method takes the newly created class as a parameter. Consider the following example: To extract a class from parameters of a function - Place the caret at the declaration or a usage of a method in the editor, or select it in the File Structure Window. - Do one of the following: - Press Ctrl+Shift+R and then choose Extract Class from Parameters - Right-click and choose Refactor \| Extract Class from Parameters on the context menu. - Choose in the main menu. - Choose whether you want to create a class or a structure and whether it should be nested in the current type or in the top level in the current namespace. - Specify a name for the new class. - Choose which parameters should become members of the new.	https://www.jetbrains.com/help/resharper/2016.1/Refactorings__Extract_Class_from_Parameters.html	CC-MAIN-2017-04	refinedweb	168	59.03
Is(); } } 6 thoughts on “#BILTNA Wish 5: Isolate with Fade” That is really really cool. I think that this combined with the Interfence Detect tool of Revit would be very useful. Great work Harry. Good tool, BUT what happen when there is some curtain walls in the projects? I get an error, I’m wandering what will happen when pinning curtain panels (which were unpinned and customized) what is the error? Autodesk.Revit.Exceptions.InvalidOperationException: Element cannot be pinner or unpinned at autodesk.revit.db.element.set_Pinned(Boolean lock) at “namespace”.IsolateAndFadeAndLock.Isolate(Icollection ‘\ eIds, doc, uidoc)… <- method I call from the external command Sorry I cannot copy the message from the revit window, maybe I will adjust the code to have a proper TaskDialog The code I posted above does not pin or unpin anything. What is the relevant element? Ops, i forgot that I’ve added the pin property to your code. It is very useful when used with the selection filter: you can work on the isolated element, without warry about selecting oher elements. Sorry about that, but, maybe I found the solution adding the .CanBeLocked method prior to lock them. Give it a try!	https://boostyourbim.wordpress.com/2018/08/10/biltna-wish-5-isolate-with-fade/	CC-MAIN-2019-47	refinedweb	198	58.08
One area of great frustration encountered by application developers involves the challenge of integrating new algorithms into a code base. There are many reasons for this. For example, the algorithm may be described in a journal article where many details of the implementation are omitted or it is available only in a programming language different from the one being used. The code may have software dependencies that are hard to resolve. The new algorithm may also have hardware dependencies, such as reliance on a GPU to get performance and you may not have access to this hardware. On the other hand, if you are the author of a great new algorithm you may be disappointed that your new invention is not being used for these very same reasons. About 18 months ago a company called Algorithmia™ was founded in Seattle that provides an elegant solution to these problems. They provide a very simple multi-language API that can be used to invoke any of their catalog of 3,500 different cloud-based algorithms. While we may be getting tired of reading about X-as-a-Service for different versions of X, there is one binding for X that has been around for a while in various forms and, as much as it pains me to do so, it begs to be called Algorithms as a Service. And AaaS is just one of the things Algorithmia provides. AaaS is indeed not a new idea. Jack Dongarra and his ICL team at the University of Tennessee created NetSolve/GridSove in 2003 to provide scientists and engineers with access to state-of-the-art numerical algorithms running on a distributed network of high performance computers. As cool as NetSolve is, Algorithmia goes several steps beyond this concept. One of Algorithmia’s cofounders and CEO, Diego Oppenheimer has a deep background in building business intelligence tools. While working on that he developed an appreciation of the power of being able to call out to powerful algorithms from inside a user facing application. This capability allows the application to have access to deeper knowledge and more powerful computational resources than available on the user’s device. A key insight from this experience is that algorithms must be discoverable an invokable from any user application runtime. These ideas are all central to Algorithmia. In the following paragraphs we will look at Algoritmia’s marketplace, explore building a new algorithm and discuss a bit of the system microservice architecture. Algorithmia is a marketplace. There are over 50,000 developers that use Algorithmia services and the platform encourages these developers to contribute new algorithms to the collection. Invoking an algorithm is dead simple and it can be done from any programming language that can formulate a JSON doc and send a REST message. We will provide some detailed illustrations at the end of this document. To use it, you need to set up an account. Doing so will get you a starter award of 5000 or so “credits”. When you invoke an algorithm, credits are deducted from your account. Typically, there is a “royalty” cost of about 10 credits and then the cost is usually around one credit per second of execution. A fun example from their library of deep learning collection is an image colorizer. Input is a PNG file of a black and white image and the returned value is a link to the output colorized image. We took a color image from a visit to Red Square a few years ago. We converted it to a grayscale image and gave that to the colorizer. The result is shown illustrated below. The original is on the left, grayscale in the middle and the colorized image on the right. While it is not as good as the best hand-colored photos, it is not too bad. It lost the amazing color of St. Bazil’s Cathedral which is not too surprising, but it was great with sky and skin tones of those people in foreground. (It seemed to think the bricks of the square would look better with some grass color.) The Python code to upload the grayscale image and invoke the service was incredibly simple. import Algorithmia client = Algorithmia.client(‘youruserkeyfromaccountrecation’) input = bytearray(open("path_to_grayscale.png", "rb").read()) result = client.algo("deeplearning/ColorfulImageColorization/1.1.6") .pipe(input).result path_to_local_copy_of_result_image= client.file(result[‘output’]).getFile() The cost in credits was 154. The exchange rate for credits is 1$ = 10,000 credits (approximately) so this invocation would have cost about 1.5 cents. This algorithm is from their extensive machine learning and AI collection. A related algorithm is one that computes the salience of objects in an image. Salience is the degree to which an object in the image attracts the attention of the viewer’s eye. The algorithm is called SalNet and it is based on ideas from the paper, Shallow and Deep Convolutional Networks for Saliency Prediction by Pan et. al. (see arXiv:1603.00845v1). As with the colorizer, salnet it is easy to invoke. input = { "image": "data://.algo/deeplearning/SalNet/perm/an-uploaded-image.png" } result2 = client.algo("deeplearning/SalNet/0.2.0").pipe(input).result Note that in this case we have loaded the image from one that we uploaded to Algorithmia’s data cloud. In fact, it is the same grayscale image of red square. As you can see below, the algorithm picks out the woman in the foreground and also notices the church in the background. Salience computation can be very helpful in identifying and labeling objects in an image. Image tagging is also something that Algorithmia supports. Running the same image through their tagger returned the observations that the image was “safe” and that there were multiple boys and multiple girls and sky and clouds and it seem to be near a palace. There are many other AI related image algorithms such as nudity detection, character recognition, face detection and a very impressive car make and model recognition algorithm. A quick look at will show many other fascinating use cases. Another very cool capability of Algorithmia is its ability to host your trained machine learning model. Suppose you have a model you have built with MsXNet, TensorFlow, Scikit-Learns, CNTK or any of the other popular ML frameworks, you can upload your model to Algorithmia so that it can be available as a service. This is explained in here. We will explore this capability in a later post. While the main emphasis and attraction of the Algorithmia collection is machine learning and AI, there are many more algorithm categories represented there. For example, there is an excellent collection of utilities for managing data and making certain programming tasks extremely easy: such as extracting text from web pages, Wikipedia search tools, computing the timezone and elevation from lat, lon coordinates. There is also a large collection of time series analysis algorithms. These include forecasting, outlier detection, Fourier filters, auto-correlation computation and many more. Algorithmia is cloud of microservices In an excellent talk at the 2017 Geekwire cloud summit, Oppenheimer described some key elements of Algorithmia’s architecture. In this talk he makes the critically important observation that two phases of machine learning, training and prediction, if used in production require very different execution environments. Training is often done on a dedicated system consuming many hours of compute and as much memory as is available. The result of training is a model codified as data. Prediction (also called Inference) uses the model to make predictions or inferences about a sample case. Prediction can be done on the same hardware platform that was used for the training, but if the model is to be used to make predictions concerning thousands of cases for thousands of concurrent users, one need a completely different design. Their approach to the scale problem for predictions (and for any high demand algorithm in their collection) is based on serverless microservices. They use a Kubernetes microservice foundation with algorithms deployed in Docker containers. Requests from remote client applications are load balanced across API servers who dispatch requests to container instances for the requested function. The challenge is making the latency from request to reply very low. If a container for an algorithm is already in system memory, it requires very little time to spawn a new instance on Kubernetes. Another technique they use it to dynamically load algorithms into running containers. (We don’t know the exact mechanism Algorithmia uses here, but we expect it is exploiting these facts.) They have made some very interesting optimizations. For example, if the data used in the computation is stored in one of their cloud regions, the docker instance will be instantiated nearby. Just as important, if an algorithm invokes another algorithm they will attempt to co-locate the two containers and reduce the inter-process latency. Composability of algorithms is one of their guiding concepts. Turning your own algorithm into a microservice. The process of turning your own algorithm into a microservice is remarkably simple. From the Algorithmia portal there is a “+” symbol in the upper right-hand corner. This give you a dialog box to fill out. You provide a name of your algorithm, the programming language you are using (from a long list .. but sorry, no Fortran or Julia but there are lots of alternatives), and several other choices including: your source license policy, does your function invoke other Algorithmia functions, does your function invoke things on the open internet? Answering these questions causes Algorithmia to create a nice GitHub repo for your function. Your next step is to install the Algorithmia command line interface and then you can clone your functions GitHub repo. Once you have done that you can edit the function so that it does what you want. The basic skeleton is already there for you in the “src” directory. Here is the basic skeleton in Python rendered as a hello world function. import Algorithmia # API calls will begin at the apply() method, # with the request body passed as 'input' # For more details, see algorithmia.com/developers/algorithm- # development/languages def apply(input): return "hello {}".format(input) You can edit the function directly from an editor built into the Algorithmia portal or, now that you have a clone of the repo you can use your own tools to transform this skeleton into your algorithm. If you have done this work on your clone you need to use the Github commands to push your code back to the master. We tried this with a small experiment. We built a function called KeyPhrases that takes English language text as input and breaks it down into subjects (s), actions (a) which are like verb clauses and objects (o). The algorithm is not very useful or sophisticated. In fact, it uses another Algorithmia microservice called Parsey McParseface which was originally released by Goolge (see pdf/1603.06042v1.pdf) . This is truly a deep parser that build a very sophisticated tree. For example the figure below illustrates the tree for a pars of the sentence Einstein’s general theory of relativity explains gravity in terms of the curvature of spacetime. Parsey McParseface tree output. Our function KeyPhrases walks the tree and groups the terms, subjects(s), objects(o) and actions (a) and returns a JSON document with the original string and the list of phrases. It also breaks out separate subphrases with “/” marks. In this case it returns {"phrases":[ "s: Einstein's general theory /of relativity ", "a: explains ", "s: gravity /in terms /of the curvature /of spacetime. " ], "text":"Einstein's general theory of relativity explains gravity in terms of the curvature of spacetime." } A more complex example is Facebook Incs chief security officer warned that the fake news problem is more complicated to solve than the public thinks. The phrase output is ['s: Facebook Incs chief security officer ', 'a: warned ', 'o: that the fake news problem ', 'a: is more ', 'o: complicated and dangerous /to solve /than the public thinks '] This is clearly not as rich in detail as the Parsey output, but it does extract some useful key phrases. To complete the creation of the microservice for this algorithm one need only issue the git commands $ git add src/KeyPhrases.py $ git commit -m "added src mods" $ git push origin master The last push causes a compile step to happen and the microservice is now created. Algorithmia also provides an easy template to add documentation and instructions about how to invoke your function. From the Algorithmia editor there is a function that allows you to “publish” your algorithm. After pushing that button, the KeyPhrase example was put in their library. You can see it here: (If you use it, remember it has not been tested very well, so it may break.) Algorithmia as an enterprise platform The Algorithmia serverless microservice platform is robust enough that they offer it as an enterprise product. This allows enterprises to host their own version on one of the public clouds or on their own clusters or across multiple cloud in a hybrid system. This allows their own internally used algorithm to be hosted and invoked by their in-house analytics tools and pipelines in a totally scalable way. This enterprise version comes with a management dashboard and monitoring tools. Conclusions Algorithmia is a fascinating company with very interesting products. It is extremely easy to sign up for a free account and it is fun to use. The team was extremely helpful when we had questions. A Jupyter Notebook with some of the examples mentioned above will be posted very soon. We found experimenting with the various algorithms from an interactive notebook was a pleasure. Creating the hosted version of the KeyPhrases algorithm took less than an hour after the original python code was debugged. In our next experiment we will explore hosting deep learning models with Algorithmia.	https://esciencegroup.com/2017/10/26/	CC-MAIN-2021-39	refinedweb	2,313	53.92
Getting Started with NodeJS Express using TypeScript TypeScript teaches some manners to write JavaScript code. A well-written JavaScript code (TypeScript) grabs much attention in the party; so why not simply include TypeScript to write Nodes Express APIs? Great idea! And both NodeJS and Express play very well with this decision. Install and initialize Typescript Without wasting much time will jump-start with this one. Lets us first globally install TypeScript if not already. The following command will help us to do so. npm i -g typescript Create a project folder where you want to start painting NodeJS Express with TypeScript. We have created a folder named tsc-express-app. Now let us initialize typescript configuration using the following command inside your project folder. This will generate a configuration file named tsconfig.json. Update the file and add the following properties to the compilerOptions property if not present already. { "compilerOptions": { "target": "es6", "module": "commonjs", "outDir": "./dist", "rootDir": "./src", "strict": true, "moduleResolution": "node", "esModuleInterop": true, "forceConsistentCasingInFileNames": true, "resolveJsonModule": true } } Here we are specifying our rootDir as “src” folder which will hold the TypeScript files and the JavaScript files which will be generated after building the project will be stored in “outDir” folder. Initialize NPM Now initialize the project using npm initialize command as follows inside your project folder. After initializing the project with default information we will start adding packages to our project. Install dependencies Add the following dependencies and dev-dependencies to your project. npm i expressnpm i -D typescript npm i -D ts-node-dev npm i -D @types/node npm i -D @types/express The -D above is for dev-dependencies. The dependencies in package.json will be as follows after running the above command. { "dependencies": { "express": "^4.17.1" }, "devDependencies": { "@types/express": "^4.17.4", "@types/node": "^13.9.8", "ts-node-dev": "^1.0.0-pre.60", "typescript": "^3.8.3" } } Here we have installed express as dependencies while the other packages as dev-dependencies, the reason behind this is that the dev-dependencies packages are only required for development and not when the project got build or deployed. So this includes typescript too. The @types/* packages are the packages that are responsible for providing meta information for packages. There are many @types/* packages are available for most of the packages. So in order to avoid TypeScript errors when running the project, we must add these @types/* packages to our dev-dependencies. In our case, we are using only express and node so we added @types/node and @types/node. The process of working with TypeScript involves building the project and then executing it. This will be done with the help of 2 sets of commands shown below: For building the project (transpiling from TypeScript to JavaScript): For running the server: node dist/server In order to speed up our development time, we have added ts-node-dev package. It does transpile our TypeScript code to JavaScript and place them into dist folder and execute our project immediately when we do any TypeScript code changes. It simply provides a watch feature to our TypeScript code so we can see changes on the fly. The command for this package is as follows: ts-node-dev --respawn --transpile-only ./src/server.ts For simplifying things, we have created our own set of NPM commands to provide some ease in doing common operations like build, start and watch. "scripts": { "start": "node dist/server", "build": "tsc -p .", "watch": "ts-node-dev --respawn --transpile-only ./src/server.ts" } Here the start will be used to run the JavaScript file which can be obtained after executing the build command. Or we can avoid these 2 steps by directly executing the watch command which will run the server and watch for any TypeScript code changes in the background. The combination of such commands are shown below: npm run build npm start// or npm run watch Setting up project Below shows the folder structure of the project. tsc-express-app \|-- dist \|-- node_modules \|-- src \|-- data \|-- employees.json \|-- models \|-- employee.ts \|-- routes \|-- employees.ts \|-- server.ts \|-- package.json \|-- tsconfig.json The dist folder will be generated once we run the npm run build command. The node_modules holds the dependencies. The src folder contains the TypeScript files. The data folder holds the static employee data in .json format, which will act as a data source for the current example. The server.ts file will start the server while the routes/employees.ts file defines the routes for employee REST API endpoints. The model here defines the data type Employee for each object present in employees.json file. Starting the server and creating API endpoints Will first create the Employee model named models/employee.ts file using TypeScript interface as shown below. export interface Employee { Id: number; Name: string; Job: string; Department: string; Code: string; } Create the API endpoints for employees inside the routes folder. The routes/employees.ts file is shown below. import express, { Router, Request, Response } from 'express'; import { Employee } from '../models/employee'; import employeesJson from './../data/employees.json';const router: Router = express.Router(); const employees = employeesJson as Employee[];// GET: api/employees router.get('/', async (req: Request, res: Response) => { try { res.json(employees.sort((a, b) => b.Id - a.Id)); } catch (error) { res.status(500).json(error); } });// GET: api/employees/:id router.get('/:id', async (req: Request, res: Response) => { try { const employee = employees.find(i => i.Id == +req.params.id); if (employee) { res.json(employee); } else { res.status(404).json({ message: 'Record not found' }); } } catch (error) { res.status(500).json(error); } router.post('/', async (req: Request, res: Response) => { try { const employee = req.body as Employee; employee.Id = Math.max(...employees.map(i => i.Id)) + 1; employees.push(employee); res.json(employee); } catch (error) { res.status(500).json(error); } });// PUT: api/employees/:id router.put('/:id', async (req: Request, res: Response) => { try { const index = employees.findIndex(i => i.Id === +req.params.id); const employee = employees[index]; if (employee) { employees[index] = { ...employee, ...(req.body as Employee) }; res.json(employees[index]); } else { res.status(404).json({ message: 'Record not found' }); } } catch (error) { res.status(500).json(error); } });// DELETE: api/employees/:id router.delete('/:id', async (req: Request, res: Response) => { try { const index = employees.findIndex(i => i.Id === +req.params.id); const employee = employees[index]; if (index !== -1) { employees.splice(index, 1); res.json(employee); } else { res.status(404).json({ message: 'Record not found' }); } } catch (error) { res.status(500).json(error); } });module.exports = router; Let us talk about the imports first, here we are importing the default express object along with classes like Router, Request, and Response. The meta definition for these classes are visible due to the dev-dependency @types/express. Next we will include the Employee interface from the model folder. Finally, we will import the employees.json data and for importing the .json file like this we have added “resolveJsonModule”: true property in the tsconfig.json file; otherwise, it will show an error for importing .json file like below. import express, { Router, Request, Response } from 'express'; import { Employee } from '../models/employee'; import employeesJson from './../data/employees.json'; We then created a router object using express.Router() method and obtained employees array from employees.json file. We have specified the type as Employee[] which will indicate the type of employees constant. const router: Router = express.Router(); const employees = employeesJson as Employee[]; We have then added endpoints for REST methods GET, POST, PUT and DELETE through which we can perform CRUD operations. Let us finally create the server to define the entry point for the application. The server.ts file is shown below. import express, { Application } from 'express' const app: Application = express(); const PORT = process.env.PORT \|\| 3000; app.use(express.json()); app.use(express.urlencoded({ extended: false })); app.use('/api/employees', require('./routes/employees')); app.listen(PORT, () => { console.log(`Server started running on ${PORT}`); }); We have defined port 3000 and also our routes for the employee API endpoints. Running the project As discussed earlier we can run the project using either build and start command or watch. We can try both. npm run build npm start For build and start, we need to, again and again, run these 2 commands whenever we change our code. So for this reason we can go with the watch command which will auto-detect change and build-run immediately for us. npm run watch NOTE: Once we are done with our development in order to deploy the project to production we must have to supply the dist folder which is generated after building the project (npm run build). Additionally, we can hit the endpoints using the api-spec.http file present in the project root folder. If we open the project inside Visual Studio Code and installed the extension REST Client then we can hit those endpoints from api-spec.http file. A more detailed explanation about NodeJS, ExpressJS with TypeScript is explained in the article (link: Building a Node.js/TypeScript REST API, Part 1: Express.js); this reading highlights the healthy typescriptive way of registering routes and maintaining the project structure. Git Repository Check out the git repository for this project or download the code. Download Code Git Repository Summary By introducing TypeScript to NodeJS we can write our JavaScript code in a controlled way. Many NodeJS packages provide support for TypeScript and have their own @types/* packages. These will provide intellisense, type safety, and strict mode for writing JavaScript code. Hope this article helps. Originally published at.	https://zakimohammed.medium.com/getting-started-with-nodejs-express-using-typescript-84f7eb25cdae?source=post_internal_links---------2----------------------------	CC-MAIN-2021-21	refinedweb	1,578	60.01
Getting Started: In order to get started, start up the Visual Studio 2005 IDE and open the included project. The solution consists of a Win Forms project with a single form and a single custom control included. The form is used as a test bed for the custom control and the custom control is an extension of the standard windows forms at run time. If you open the code up and examine the imports, you will note following imports prior to the namespace and class declaration. using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Drawing.Drawing2D; using System.Text; using System.Windows.Forms; namespace Gradient..	http://www.c-sharpcorner.com/UploadFile/scottlysle/GradientPanel12052006225613PM/GradientPanel.aspx	CC-MAIN-2015-40	refinedweb	114	54.18
Multi-Label Anisotropic Euclidean Distance Transform 3D Project description Python Instructions for MLAEDT-3D Compute the Euclidean Distance Transform of a 1d, 2d, or 3d labeled image containing multiple labels in a single pass with support for anisotropic dimensions. Python Installation Requires a C++ compiler The installation process depends on edt.cpp for the Python bindings derived from edt.pyx. edt.hpp contains the algorithm implementation. pip install numpy pip install edt Recompiling edt.pyx Requires Cython and a C++ compiler cd python cython -3 --cplus edt.pyx # generates edt.cpp python setup.py develop # compiles edt.cpp and edt.hpp # together into a shared binary e.g. edt.cpython-36m-x86_64-linux-gnu.so Python Usage Consult help(edt) after importing. The edt module contains: edt and edtsq which compute the euclidean and squared euclidean distance respectively. Both functions select dimension based on the shape of the numpy array fed to them. 1D, 2D, and 3D volumes are supported. 1D processing is extremely fast. Numpy boolean arrays are handled specially for faster processing. If for some reason you'd like to use a specific 'D' function, edt1d, edt1dsq, edt2d, edt2dsq, edt3d, and edt3dsq are available. The three optional parameters are anisotropy, black_border, and order. Anisotropy is used to correct for distortions in voxel space, e.g. if X and Y were acquired with a microscope, but the Z axis was cut more corsely. black_border allows you to specify that the edges of the image should be considered in computing pixel distances (it's also slightly faster). order allows the programmer to determine how the underlying array should be interpreted. 'C' (C-order, XYZ, row-major) and 'F' (Fortran-order, ZYX, column major) are supported. 'C' order is the default. parallel controls the number of threads. Set it <= 0 to automatically determine your CPU count. import edt import numpy as np # e.g. 6nm x 6nm x 30nm for the S1 dataset by Kasthuri et al., 2014 labels = np.ones(shape=(512, 512, 512), dtype=np.uint32, order='F') dt = edt.edt(labels, anisotropy=(6, 6, 30), black_border=True, order='F', parallel=1) Project details Release history Release notifications \| RSS feed Download files Download the file for your platform. If you're not sure which to choose, learn more about installing packages.	https://pypi.org/project/edt/	CC-MAIN-2021-10	refinedweb	382	61.22
import "bitbucket.org/advbet/sseclient" Package sseclient is library for consuming SSE streams. Key features: Synchronous execution. Reconnecting, event parsing and processing is executed in single go-routine that started the stream. This gives freedom to use any concurrency and synchronization model. Go context aware. SSE streams can be optionally given a context on start. This gives flexibility to support different stream stopping mechanisms. Code: package main import ( "context" "log" "time" ) func errorHandler(err error) error { log.Printf("error : %s", err) return nil } func eventHandler(event Event) error { log.Printf("event : %s : %s : %d bytes of data", event.ID, event.Event, len(event.Data)) return nil } func main() { c := New("", "") ctx, cancel := context.WithTimeout(context.Background(), time.Minute) defer cancel() c.Start(ctx, eventHandler, errorHandler) } MalformedEvent error is returned if stream ended with incomplete event. type Client struct { URL string LastEventID string Retry time.Duration HTTPClient http.Client Headers http.Header } Client is used to connect to SSE stream and receive events. It handles HTTP request creation and reconnects automatically. Client struct should be created with New method or manually. New creates SSE stream client object. It will use given URL and last event ID values, default HTTP client from http package and 2 second retry timeout. This method only creates Client struct and does not start connecting to the SSE endpoint. func (c *Client) Start(ctx context.Context, eventFn EventHandler, errorFn ErrorHandler) error Start connects to the SSE stream. This function will block until SSE stream is stopped. Stopping SSE stream is possible by cancelling given stream context or by returning some error from the error handler callback. Error returned by the error handler is passed back to the caller of this function. Stream is non-blocking SSE stream consumption mode where events are passed through a channel. Stream can be stopped by cancelling context. Parameter buf controls returned stream channel buffer size. Buffer size of 0 is a good default. ErrorHandler is a callback that gets called every time SSE stream encounters an error including errors returned by EventHandler function. Network connection errors and response codes 500, 502, 503, 504 are not treated as errors. If error handler returns nil, error will be treated as handled and stream will continue to be processed (with automatic reconnect). If error handler returns error it is treated as fatal and stream processing loop exits returning received error up the stack. This handler can be used to implement complex error handling scenarios. For simple cases ReconnectOnError or StopOnError are provided by this library. Users of this package have to provide this function implementation. var ( ReconnectOnError ErrorHandler = func(error) error { return nil } StopOnError ErrorHandler = func(err error) error { return err } ) List of commonly used error handler function implementations. Event object is a representation of single chunk of data in event stream. EventHandler is a callback that gets called every time event on the SSE stream is received. Error returned from handler function will be passed to the error handler. Users of this package have to provide this function implementation. StreamMessage stores single SSE event or error. Package sseclient imports 9 packages (graph). Updated 2019-04-26. Refresh now. Tools for package owners.	https://godoc.org/bitbucket.org/advbet/sseclient	CC-MAIN-2020-34	refinedweb	529	60.51
Is the following statement true?? How is geronimo being able to process deployment plans without declaring all namespaces in a plan and qualifying the elements? Sachin. -------- Original Message -------- Subject: Re: rid of all ns prefixes Date: Tue, 11 Oct 2005 12:56:09 -0600 From: Dave Carlson <dcarlson@xmlmodeling.com> Organization: XMLmodeling.com Newsgroups: eclipse.tools.emf References: <digsvf$1v5$1@news.eclipse.org> <digtfs$2n8$1@news.eclipse.org> <digu6l$3ml$1@news.eclipse.org> The XML spec does not require a schema for well-formed XML documents. From your description, it sounds like Geronimo has written a custom application that "knows" how to load the XML stream without reference to any schemas. Unfortunately, it is impossible to use a general purpose modeling tool like EMF (or any other Java-binding framework) without well-defined schemas and their required namespaces/prefixes. "Sachin Patel" <sppatel2@gmail.com> wrote in message news:digu6l$3ml$1@news.eclipse.org... > What I'm generating is the server specific deployment descriptors for > Apache Geronimo. I see what you are saying, and I'm not sure exactly how > the server is able to load the plans without the namespace declarations, > but when creating these plans for Geronimo, the elements without being > qualified are able to be loaded and processed by the server. Will post on > their dev list on how exactly they are accomplishing this, but I would > like to take those existing plans from there "samples" which contain > contain no qualified elements and be able to load and parse them with my > EMF model. > > So its more of a compatibility reason for which I need to be able to do > this. The sample applications in geronimo should be able to be imported > into WTP and be processed my EMF model which are based on the same exact > schemas. But the xml files in these sample applications do not contain > fully qualified elements. > >	http://mail-archives.apache.org/mod_mbox/geronimo-dev/200510.mbox/%3C434C0D54.7010900@gmail.com%3E	CC-MAIN-2016-07	refinedweb	318	54.63
fix: crontabfile -> crontab fix: resolve broken parts after refactor fix: drop weird line This is my fork of pcrond with some small improvements and fixes to make it actually work. Userspace cron daemon A daemon similar to the standard cron daemon, however it is designed to run in userspace, not as root. Jobs scheduling use exactly the same formalism of crond. Written in Python. Some of the code was taken from schedule project. This project is not interested in the "human stuff" of the original project. $ ./setup.py install --prefix=~/.local This assumes that ~/.local/bin is in the PATH which is quite common $ pcrond -c path/to/my/crontab/file It is also possible to use this library within your Python program, however this is not the intended use. For example: from pcrond import Scheduler scheduler = Scheduler() scheduler.add_job("30 4 * * 0", my_python_func) # runs every sunday at 4:30 scheduler.main_loop()	https://git.sr.ht/~yerinalexey/pcrond	CC-MAIN-2022-40	refinedweb	152	66.94
Word vector models represent each word in a vocabulary as a vector in a continuous space such that words that share the same context are “close” together. Being close is measured using a distance metric or similarity measure such as the Euclidean distance or cosine similarity. Once word vectors have been trained on a large corpus, one can form document vectors to compare documents based on their content similarity. A central question is how to obtain “good” word vectors in the first place. For this various models based on neural networks have been proposed, one of the most popular ones being word2vec. In the “continous-bag-of-words” (CBOW) architecture of word2vec, word vectors are trained by predicting the central word of a sliding window given its neighbouring words. This is formulated as a classification problem, where the correct central word has to be selected among the full vocabulary given the context. Usually one would use a softmax classifier as the top layer of such a network. However, for the softmax the training time grows linearly in the number of possible outcomes, making the method unsuitable for large vocabularies. Hierarchical softmax Hierarchical softmax has been proposed in the context of language models to speed up training by Morin and Bengio (2005), following prior work by Goodman (2001). The idea is to decompose the softmax layer into a binary tree with the words of the vocabulary at its leaves, such that the probability of a word given a context can be decomposed into probabilities of choosing the correct child at each node along the path from the root node to that leaf. This reduces the number of necessary updates from a linear to a logarithmic term in the vocabulary size. To choose a concrete tree for training a language or word embedding model, a number of techniques have been proposed. The original work by Morin and Bengio built the tree manually using hierarchical relations extracted from WordNet. Mnih and Hinton (2008) used a bootstrap variant where word vectors were trained based on a random tree, after which those were used to derive a semantically inspired tree by top-down clustering. The subsequent training using this semantic tree provided significant improvements over the random tree. Finally, Mikolov et. al. (2013) used a binary Huffman tree based on word frequency counts that focussed solely on training efficiency by assigning the shortest paths to the words that occur most often. This is also the version of hierarchical softmax that is implemented in Google’s word2vec code and Facebook’s fastText library. Using semantic trees to train word embeddings The idea to use a semantic tree seems natural, given that at each node, a binary classifier has to decide whether the given context vector fits better to the left or right child node. If the tree is built without any semantic knowledge, very similar words could end up on separate sides, making it very hard to train a good classifier and thus get a consistent error term for backpropagation. Imagine, for example, that the sentence “cats and dogs are animals” is the current context window, so that the word “dog” should be predicted from the context “{cats, and, are, animals}”. If, for example, the words “dog” and “dogs” are in separate child nodes at a very high level of the tree, the classifier most likely won’t be trained to achieve a high confidence. The same holds true if, for example, different animals are separated into different child nodes at an early stage. The papers cited above that use semantic trees are all dealing with language models, i.e. predicting the next word given neighbouring words. The quality of a trained language model is usually evaluated using perplexity. In the context of word embeddings, this prediction task is only a tool to obtain good word vector representations, and it is not clear whether training methods that produce better language models actually transfer to better word embeddings. Therefore we wanted to try the approach of Mnih and Hinton (2008) for training word vectors from a corpus of Wikipedia documents and evaluate them using common word analogy and word similarity tasks. Experiments To train word vectors using hierarchical softmax with arbitrary trees, we modified the fastText code to accept a parameterization of a precomputed binary tree as an additional parameter. In order to obtain a first set of word vectors, we trained a CBOW model using fastText on a dump of English Wikipedia from 2013 that has been filtered to contain only articles with at least 20 page views. This amounts to 463,819 documents with 498 million words. The hyperparameters we used were -minCount 25 -minn 0 -maxn 0 -t 0.00001 -lr 0.05 -ws 10 -epoch 3 -loss hs This means that only words that occur more than 25 times in the corpus are considered, there are no vectors trained for character n-grams, and training is run for 3 epochs with learning rate 0.05, subsampling parameter 1e-5 and window size 10. The dimension of the embeddings was set to 50, 100, and 400 to assess the influence of the dimension on the performance. Using the -loss hs parameter for the hierarchical softmax loss function implies constructing a Huffman tree. Thus, from a semantic point of view, this tree can be considered random, giving a similar baseline as in Mnih and Hinton’s paper. After the training finished, the resulting word vectors were clustered into a binary tree using a two-component Gaussian mixture model with spherical covariances. In the beginning, all word vectors are used and split into two components based on the posterior probability the GMM assigns to them. Then, at each step, all the vectors that are assigned to a leave node are split again into two components until the leaves of the tree only contain one word. Concretely, given a node of the tree with vectors node.vecs, the assignment to the left and right child nodes is computed as: from sklearn.mixture import GaussianMixture as GMM gmm = GMM(n_components=2, covariance_type='spherical', verbose=0, max_iter=10) gmm.fit(node.vecs) classes = gmm.predict(node.vecs) vecs_left = node.vecs.iloc[np.where(classes==0)] vecs_right = node.vecs.iloc[np.where(classes==1)] Given the final assignment of words to leaves, a codeword for each word in the vocabulary can be computed, where the n’th bit is set to 0 if the path from the root to that word takes the left child node at the n’th level of the tree, and 1 if it takes the right child node. The resulting data of vocabulary words together with code words and an enumeration of the internal nodes of the tree can then be fed into our modified version of fastText to use this semantic tree instead of the Huffman tree. Inspecting the resulting tree Given that we expect a semantic structure to emerge from the clustering, we wanted to check this subjectively by visualizing the resulting trees. To that end, a node was represented by the words most similar to its component mean vector from the GMM training. Then the Graphviz visualization library was used to construct images at different levels of the tree. A semantic tree, truncated at the eighth level, looks like this: Zooming in on the root node, it is very interesting to compare the most representative words for the two child nodes. One could say that one node is best described by persons and emotions whereas the other one represents rationality and objectivity. Some further splits into more and more refined categories can be observed at deeper levels of the tree: Evaluation We trained two models, one using the Huffman tree and one using the semantic tree constructed as above. Other than the difference in trees, the hyperparameters were identical in the two cases. For evaluation we used the original word analogy task of word2vec and a word similarity task based on the Stanford rare words (rw) similarity dataset (see here for details). The word analogy evaluation was run using Gensim’s built-in accuracy function, whereas the word similarity evaluation is based on this evaluation script provided in the fastText repository. For the word analogy task, only the most frequent 30,000 words are considered. The resulting scores can be seen in the figures below: In general, the semantic tree outperforms the Huffman tree. However, this effect lessens as the dimension of the embedding increases. Interestingly, this is exactly the same as observed by Mnih and Hinton for the perplexity of language models, despite language modelling being a different task than word analogy and similarity learning. The vocabulary resulting from the minCount cutoff contained 213,480 words. Clustering the word vectors in dimension 400 took around 13 minutes, which seems pretty efficient. Another interesting thing that could be observed was that the average logistic loss that is reported by fastText was less for the semantic tree than for the Huffman tree at the end of training. This confirms the hypothesis that it is easier to learn good classifiers along the tree nodes if the partition makes sense semantically. Code The code for running the experiments is available via GitHub. The modified version of fastText can be found in this repository and an iPython notebook for running the full experiment is available here. The Wikipedia dump we used for training is made available here. Otherwise, any public corpus of a decent size should lead to similar results. You might want try out the dataset used in this example. References Goodman, J. (2001). Classes for fast maximum entropy training. ICASSP 2001, Utah. pdf Morin, F., & Bengio, Y. (2005). Hierarchical Probabilistic Neural Network Language Model. Aistats, 5. pdf Mnih, A., & Hinton, G. E. (2008). A Scalable Hierarchical Distributed Language Model. Advances in Neural Information Processing Systems, 1–8. pdf Mikolov, T. et. al. (2013). Efficient Estimation of Word Representations in Vector Space. Arxiv. pdf	https://blog.lateral.io/2017/09/semantic-trees-hierarchical-softmax/	CC-MAIN-2020-50	refinedweb	1,659	51.58
#include <gromacs/utility/keyvaluetreetransform.h> Provides methods to specify one transformation rule. The builder is implemented as a set of nested objects, each of which is provides methods for setting a particular property of the rule. Setting a property returns another object that has relevant methods for the context. This provides some structure to the methods, and catches at least some types of incorrect rules already at compile time. Additionally, if you use an IDE with completion facilities, it can nicely guide you through which values you need to specify. All values are stored within the main builder object, and the rule is created at the end of the statement. Specifies a rule that maps a value at given path. If the input tree has path, but it is not of type FromType, the transform will produce an error. It is an error to use the same path in two from() rules. Similarly, it is an error to use a child path of a path used in a different from() rule. Specifies how strings are matched when matching rules against a path. For properties of the object at path, keyMatchType is used for string comparison. This rule must be specified first for a path, before any other from() rule specifies the path or a subpath. The rule only applies to immediate properties at the given path, not recursively. It is an error to specify the match type multiple times for a path.	https://manual.gromacs.org/current/doxygen/html-full/classgmx_1_1KeyValueTreeTransformRuleBuilder.xhtml	CC-MAIN-2021-39	refinedweb	242	63.8
Hot Deployment is flucky to say the least and drives me nuts. I have altered the profiles.xml file to not exclude WEB-INF/dev. Sometimes the components get reloaded but sometimes not (POJO components see below). I can see the timestamp of the classes changing in WEB-INF/dev but SEAM does not pick them up sometimes. Consider the following POJO: public class SayHello { @Logger private Log log; @In StatusMessages statusMessages; // @In // Identity identiy; public void sayHello() { // implement your business logic here log.info("sayHello.sayHello() action called!"); statusMessages.add("sayHello.sayHello() test!"); } } If you change the statusMessage hot deployment works fine. Now remove the comments and inject the identity hot deplyment doesnt work anymore. If you do a full deploy you will find out that you need @In(required=false) What is really the issue here, is that even if you fix the error, hot deployment will not start to work until you have done a full deployment. In IMHO this make Seam hot deployment unusable. Perhaps I miss something here that breaks my hot deployment. Any advice how to fix this? Do experience the same issue? Shall I make a JIRA entry? JBoss-5.1/EAP-5.1, Seam-2.2.1.Final, Eclipse Helios R1, JBossTools nightly builds (26/2/11) but I don't think it is the IDE.	https://developer.jboss.org/thread/193741	CC-MAIN-2017-26	refinedweb	224	67.35
Applies To: Users – Portal Developers and Consultants, NWDI / NWDS Developers Version – SAP Netweaver Portal 7.31, Netweaver Developer Studio 7.31 SP7 Summary: This document explains in detail how to use NWDI for Portal developments using WAR files. Background: We upgraded our Portal from 7.0 to 7.31 which was a huge leap forward and there was so much things we need to consider while doing this upgrade. In 7.0 all Portal components used were all PAR files and now there are no PARS. You will have to migrate all these files. One of the challenges we had was modifying the standard Portal logon page. We had to go through numerous documents on how to modify the logon pages, how to modify the war files in NWDS using NWDI and how to package the war file into an ear and deploy to the server. All the pains gone through to make that a success is the reflection of this document. Solution Implementation: Now, lets jump on to what we are here for. 1. Open your NWDS and logon to NWDI. Navigate to the Development Configuration in which you would like to create this new development component. 2. Create a Web Module Development Component. 3. Give the Web Module DC Details. Click finish. This will automatically create an activity in NWDS and attach all the files and folders to it respectively. 4. It’s time to now import the standard logon file from the server that was downloaded. Right Click on the DC and import WAR File. 5. Select the War File Location and a new local Web project name where the contents will be uploaded. 6. In the above step the default jar files will be added to the lib folder in the local web project. Additional jar files that are required to be added to eliminate the errors in jsp’s can also be added. 7. Copy the Web Content Folder of local project and replace the web contents folder inside the NWDI DC. 8. Modify the JSP Files as required to customize your logon screen. Build the DC. 9. This DC is not directly deployable. You will need to package this into another DC of type Enterprise Application. 10. Give the DC Details. 11. Select the Web Module Project in the Next Screen so the WAR file is added to the deployment descriptor of the the new DC created for deployment. 12. Modify the application-j2ee-engine.xml file in the DC as below. Provider name for the application is usually your client name. The provider name defines your namespace where your applications reside on the AS Java. 13. Now, Right click on your DC and Java EE Tools > Generate Deployment Descriptor Stub. This will generate application.xml file. 14.The application.xml file will look like the below. By default the Context-Root will be referring to the Web Module DC you created but you can modify the Context-Root Name to a different one which will be used in the NWA Configuration for the logon page. 15. Build your DC and Deploy it to the server. Hurray !!! Next Step is your nwa configuration where you need to give the context-root name that we used above and restart the server. Nice blog..! Many portal developers asked questions on this process. Thanks Uday !!! HI Nagarajan, Nice blog, we are also in same version 7.31 SP7, and no nwdi in place, when i imported login war file to NWDS i got a “mobile” folder and all jsp files contains syntax errors, even in Web Inf Jsp pages i am getting some error. do you face/ get this Mobile folder issue in your implemenation?. plese suggest (added required 2 jar files( regards, mahesh Hi Mahesh, Yes. The Mobile Folder and its contents shows errors to me as well. I did not explore those because we did not need those implementations currently. Except the mobile folder I do not get any issues. Did you add the 2 jars (tc~sec~ume~logon~logic_api.jar, tc~sec~ume~logon~ui_core.jar) inside the WEB_INF –> Lib folder? Did you add those Jars to your project build path? Try to close the project and open. Sometimes a refresh would clear all the error it might regenerate. Thanks, Nagarajan HI Nagarajan, Yes, i added those two Jar files inside Web- inF and Bulid path, still i got the syntax error in every JSP file in Web INF . the error is in Java Script tags, either “Syntax error on Token } and you can delete this token” or “Syntax error, Insert } to complete Block Sttatement” you can help me in this thread on the same isssue: regards, mahesh Hi Nagarajan, could you please explain the step 11. a little bit more? When i create a new DC (Step 9) of type Enterprise Application, i do not get a next window like in step 11, where i could add the web module project to the new DC?! thanks, Lars Hi folks! The easiest way to change picture and text is to upload two files to your server to following directories: /usr/sap/<SID>/J00/j2ee/cluster/apps/sap.com/com.sap.ip.bi.web.portal.mimes/servlet_jsp/com.sap.ip.bi.web.portal.mimes/root/base.framework/resources/layout/ /usr/sap/<SID>/J00/j2ee/cluster/apps/sap.com/com.sap.security.core.logon/servlet_jsp/logon_ui_resources/root/layout/ branding-text-new.gif (325 x87) branding-image-new.jpg (290 x 360) Then change picture name in NWA like described above – that´s all! (ume.logon.branding_image): (ume.logon.branding_text): No deveplopment kit and no restart is needed! Enjoy! Juergen Like (0) EditDeleteReply Hi All, I create my Logon DC as per your suggestions and builded. But in deployments i am getting EAR files are deployed but warnings. Its looking for tag libraries Warning message Cannot parse jsp [/usr/sap/P0N/J20/j2ee/cluster/apps/com.jnj.mercury/com.jnj.mercury.logonear/servlet_jsp/mercury_loginmodule/root/logonPage.jsp]. Error is: [Cannot parse custom tag with short name [form].]. Warning occurred on server 203474751 during startApp of com.jnj.mercury/com.jnj.mercury.logonear : Cannot parse jsp i compared all files from local project to DC. Every things looks same. Regards, Narayana	https://blogs.sap.com/2013/08/13/nwdi-731-portal-logon-screen-modification-2/	CC-MAIN-2019-13	refinedweb	1,044	65.93
I have tried to remove myself from this list using the known options - but to no avail. How can i get off this list. Casey Lucas wrote: > Costin, > > Thanks for the information, but because I'm still new to the tomcat > code base, I'm a bit confused. > > Maybe it will help if I explain a little more about what I was playing > around with: > > 1. Add a few classes (pooling interfaces/implementation) to jasper.runtime > package so that rendered jsp's could use them. > > 2. Change Jasper to render code to use tag pooling. This means changes > to ...jasper.compiler.JspParseEventListener and maybe a couple of > additional jasper.compiler.*Generator classes that would render > tag pooling specific stuff. > > Given these assumptions: > - org.apache.jasper.runtime.TagHandlerPool is the interface that > specifies tag pooling. > - org.apache.jasper.runtime.TagHandlerPoolManager is the interface that > allows different pooling strategies and gives out TagHandlerPools > - poolForTagX will be some better _jspx_... generated name. > - "pool name for tagX" will be some unique name (per reuse scope - > taking into account attributes, tld, etc.) > - TagHandlerX is substituted for the tld specified tag handler > > The new rendered code could look something like: > > public class _0002ftestdocs_0002fquestions_0002ejspquestions_jsp_4 extends HttpJspBase { > > static { > } > > // 2 lines below are new. > private TagHandlerPool poolForTag1; > private TagHandlerPool poolForTag2; > > public _0002ftestdocs_0002fquestions_0002ejspquestions_jsp_4( ) { > // 2 lines below new. assume that TagHandler1 and TagHandler2 are > // tag handler classes (from tld) > poolForTag1 = TagHandlerPoolManager.getDefaultManager(). > getPool("pool name for tag1", TagHandler1.class); > poolForTag2 = TagHandlerPoolManager.getDefaultManager(). > getPool("pool name for tag2", TagHandler2.class); > } > > private static boolean _jspx_inited = false; > > public final void _jspx_init() throws JasperException { > } > > public void _jspService(HttpServletRequest request, HttpServletResponse response) > throws IOException, ServletException { > > ======== end of code ======== > > Then inside of _jspService, code would be rendered to use the appropriate "poolForTagX" > object to get/release tag handlers. > >? > > Am I off base, with my general strategy? > > Also, regarding 3.x and 4.x, I'd like to keep it usable / adaptable > to all. We're currently using 3, but will eventually migrate to 4. > > thanks. > -Casey > > > -----Original Message----- > > From: cmanolache@yahoo.com [mailto:cmanolache@yahoo.com] > > Sent: Friday, March 09, 2001 11:48 AM > > To: tomcat-dev@jakarta.apache.org > > Subject: Re: where to plug-in startup/shutdown knowledge for internal > > tomcat components > > > > > > Hi Casey, > > > > This is a hard question :-) > > > > The main decision you must make is that: > > > > Do you want to use JspServlet or JspInterceptor ? > > > > The first solution ( using Jasper via JspServlet ) is what is used in > > tomcat 3.1, 3.2 and 4.0 - and it has the big advantage that the full > > Jasper in interfaced using a normal servlet. That means jasper can be used > > in any place where a servlet can be used, and integrating it into any > > servlet container should be trivial. > > > > The second solution is used in tomcat 3.3 ( JspServlet is still > > supported). JspInterceptor is an adapter between tomcat 3.3 internals ( > > i.e. the hooks provided to tomcat 3.3 modules ) and Jasper's APIs ( > > Mangler, JspCompiler, etc). It works in the same way as JSPC - where a > > command-line interface to jasper is provided, with a lot of options. > > This is extremely flexible and gives you full access to all jasper's > > features, it allows a number of optimizations ( like avoiding the double > > redirection - JspServet->generated servlet), allows treating > > jsp-generated servlets as normal servlets ( i.e. absolutely no extra > > overhead or difference between a jsp and servlet after the compilation), > > and is much cleaner. > > > > It is also possible to adapt jasper ( not as easy as with a servlet ) to > > other containers by writing an adapter between Jasper's APIs and the > > container's internal APIs. > > > > In any case, remember that Jasper-generated servlets can be used via JspC > > - i.e. pre-compiled into servlets, without any jsp-specific code ( > > JspInterceptor acts like a runtime JspC ). So putting your code into > > JspServlet will be a bad choice. > > > > One way is to use tomcat3.3 hooks ( contextInit, reload, > > requestMap, pre/postRequest, etc ), and eventually take advantage of the > > per/request ( and thread ) and per context storage ( in 3.3, each Thread > > has it's own set of Request/Response - so request notes are equivalent > > with per thread data ). > > > > The other way is to do tricks in the generated servlet. For example > > on init() you can check a context attribute, and if not set you can do the > > context initialization and set the attribute. As long as you use > > "global" objects, reloading shouldn't affect you. You can use jasper > > runtime object to put the common code, so the generated code will remain > > small. > > > > Both solutions have advantages - and it's even possible to do a > > mix. > > > > My recomandation - just use a SimplePool, implement the "real" code ( tag > > pooling ), without worry about how the pool will look like or will be > > hooked. After this works, we'll find a solution ( or 2 ) for this issue. > > > > > > Costin > > > > > > On Fri, 9 Mar 2001, Casey Lucas wrote: > > > > > > > > I'm doing some prototyping for tag pooling in tomcat (based on > > > the 3.3 tree.) I'd like to implement tag handler pooling > > > per web application. Can someone point me to where I can > > > hook into in order to setup the internal pool stuff when > > > each web application starts, stop, reloads, etc.? > > > > > > I need to do things like setup the pooling strategy > > > when each web application starts and release all the tag > > > handlers when the application shuts down. > > > > > > Sorry if this is a dumb question, but hopefully someone > > > can save me a lot of time. > > > > > > thanks. > > > > > > -Casey > > > > > > --------------------------------------------------------------------- > > >	http://mail-archives.apache.org/mod_mbox/tomcat-dev/200103.mbox/%3C3AA9388F.FE853EFA@irista.com%3E	CC-MAIN-2014-15	refinedweb	912	57.47
.god Domain Names: Another "Pioneer" Registrar 211 commodoresloat writes: "According to this article, the top-level domain (TLD) .god will soon be available. Most interesting is that Joe Baptista, who will be selling domain names under the TLD, says outright that he will not respect trademarks or even court decisions ordering him to respect trademarks. Does this mean anyone can register microsoft.god?" Available, maybe, but not very useful if ICANN doesn't care to ever recognize them. Note, though, the site is only semi-functional. "The registry will allow you to look up dot.god names for availability but it will not allow you to register at this time." Pity. I hope CmdrTaco gets credit. Re:Viva la Revolution! (Score:2) I suggest that something like the GNUtella approach be applied to domain names. You could search for "Microsoft" and get not only Microsoft,.com but 3712 MSCE's personal home pages, 38 pages of Microsoft jokes, "Windows Millennium Annoyances" and 7253098 Linux sites... Hm, then DNS would become the search engine, which didn't occur to me when this idea popped into my head... Maybe this idea is way out there, but there it is. --- Re:Interesting (Score:1) Paul Bryson how? (Score:1) Re:affidavit? (Score:1) Actually, being a party is not a requirement. source=. DB Re:Hoax? (Score:1) Re:Who does this guy think he is? (Score:1) Re:DOES GOD HATE YOU? (Score:2) >Yes, but you can only run one of the following operating systems >Windows 3.0 >Windows NT 3.1 >It is, after all, hell >DB ugh.. first time someone actually came close to converting me... //rdj Re:DOES GOD HATE YOU? (Score:2) Yes, but you can only run one of the following operating systems Windows 3.0 Windows NT 3.1 It is, after all, hell DB Re:Egos (Score:2) Revolution! Namespace Protectionists Unite! (Score:1) Seriously, TLDs are totally unreliable when it comes to determining information about a site. Non profit organizations and non-US businesses have While I'm ranting-- and since crazed Andy Rooney mode is on, I propose that the government establish some kind of Namespace Protection Agency. Our English word domain names are IN DANGER of extinction! Much like the great Sequoia groves of California and Amazon rain forests, businesses are now destroying the beauty of hierarchical categorization! The DNS tree, our Sequoia, once stood proud and balanced to give us O(log n) computational complexity in the worst case. Alas now it is but O(n)! (Proof is left as exercise to reader.) Perhaps there is no way to encourage the use of more structured, discernible domain names. Perhaps we are doomed to a single business hoarding thousands of second level domain names, virtual-hosted and without useful content. We can at least try to protect the most valuable and precious strings in our namespace. Here's the plan: we give second-level Re:Offtopic rant (Score:1) Re:Viva la Revolution! (Score:1) OTOH...I actually would like TLDs that mean something. It would really be nice to be able to tell something about the nature of the group that has the domain by the TLD. you know, back in the day having a pity it doesnt seem to work. ACZ Re:Pathetic... (Score:1) -- Daniel Zeaiter daniel@academytiles.com.au ICQ: 16889511 I want no.master.no.god! (Score:1) Re:New idea? (Score:1) It would assist with filtering... (Score:1) Also, maybe it would stop people getting thousands of church URLs everytime they try to search for their porn... what will the church say? (Score:1) Calculated to offend.. (Score:1) Get moving ICANN! and what about case- sensitivity? will - well dang... (Score:1) (hmm, will anybody see this 5 days after the fact?) Re:Cripes... (Score:1) Re:Opportunity missed. (Score:1) Re:Too many TLD's (Score:1) Of course, that's also why there were IP Network classes. Now there are tons of Classless networks, and the routing tables are just plain huge. <sarcasm> soon, we'll see the advent of TLDv6....</sarcasm> sigh Can't Any of Us Do This? (Score:3) This is just stupid. -Waldo Hmmm... (Score:1) Okay, it's probably not original, but It let me sign up for it! Hasta luego Exantrius Why... (Score:1) I can just picture him after the ruling to break up M$, on the news saying: "We offered a comprimise to the DOJ, but they turned it down. So now my mechanical slaves will take over the world! Hahahahaha ALL HAIL MICROSOFT!" Then all TV screens all over the world turn black and then display the M$ logo. He will have support too because there were subliminal messages in all Windows operating systems. Then the rebels will gather in preperation to invade Redmond. They will airlift a penguin into the M$ building, who is hiding machine guns and bombs under its wings. It blows past Bill's minions and gets to the secret underground lair, just in time to see Bill putting on his human skin (he IS a robot after all!). Bill is alarmed and pushes a button under his desk, which sends in hundreds of killer robots that surround our hero. Fortunatly, all the robots are running Windows CE and they happen to come up with an "Illegal Error"! They all fall down, useless. However Bill is still active because he just rebooted, so he has about 30 seconds left until he crashes, and with no one to revive him, he is doomed. But Tux wants to take him out in style, so he aims, and... "HASTA LA VISTA BABY!!!!!". The world is once again safe for democracy. Alternate DNS... GOOD (Score:1) There was never anything saying that there had to be just one system, and I for one would like to see alternate systems. It would create more redundancy, and probably would make it too difficult to bring stupid lawsuits against people who "have your trademarked domain" like the whole toys.com deal a while back. Making multiple systems would increase choice and impartial organizations for end users. And no, multiple registration authorities will not be the same. It's just not seperate enough. Everyone is still limited by the same TLDs and the same general system. Just my two cents. Re:I want to register is.god.. (Score:1) Quotes are my friends. (Score:2) Intersting Psychological Moment (Score:1) It means that his claim of "not respecting trademarks and courts" might be a psychological pressure in order to push these corporations and collect a lot of registration fees. Re:I want to register is.god.. (Score:1) My Politikal Correctness (Score:1) Oh Great! (Score:1) Re:idiot (Score:1) only the beginning (Score:2) This is probably the beginning of the current centralized naming system. People can set up name resolution on their own computers any way they like. If .GOD becomes popular, people will add it to their name resolvers so that they can resolve URLs that refer to it. You are probably also going to see little programs that make it easier to reconfigure name resolution statically or even on the fly. In fact, ActiveX components or VBScript "attachments" may be ever so helpful to users to do this automatically. The main constraint is that if users see a URL, they probably want to be able to resolve the host name to something that exists (but not always--I'd be happy never to resolve the advertisers). That will mean that in the short run, there will remain a core set of name servers that everybody will refer to. In the long run, browsers will probably almost exclusively use search engines to locate pages, the location bar will disappear, companies will use registered trademarks in ads to allow consumers to locate them ("look us up on the web under FooBar(TM)"), and URLs themselves will be replaced by something location independent. And the dealing in .com domain names will look like tulip mania in retrospect. At least we can hope. A darker possibility is that, in the process of migrating to a URL-less world, the ISPs will take over name resolution and locating content for you entirely so that you only get to see the pages they want. And it may also be more difficult to get personal or other oddball pages into the directories people will be using. Two Unrelated Issues? (Score:1) Re:Hoax? (Score:1) I want .falco (Score:2) Lets have a .falco as well. Then when .coms like boo implode, we just move their registrations over to the .falco TLD. Whats a Falco ?/a> [ntk.net] My god? (Score:1) Yep - sounds good to me what interests me most... (Score:3) Re:No, only allow 3rd or 4th level domains. (Score:1) Absolutely. A flat naming system will end up helping absolutely no one. Those that propose abolishing TLDs are absolutely clueless. What we really need is a good standardized selection of 2LDs to be under a country TLD. (If you're truly international and not based in any country you get .int - simple.) If one country (say the US) wants to let XYZ Corp register xyzcorp.com.us, xyzcorp.net.us, and xyzcorp.web.us, that's up to whomever is in charge of the .us TLD. Personally I feel that proper usage of these 2LDs should be enforced. The web is not about trademarks. It's about finding information. The system should be helping you do that. I've currently got a .org address but I always wanted to be a .web. It's just an online activity, I'm not a non-profit organization! As far as switching to this new system, I think it should be an all-at-once deal. "At midnight GMT January 1, 2001, the new domain names will go into effect. Please make a note of it." If you allow a transition period, everyone's going to want to keep clinging to their old names. .odd (Score:3) Of course, this does leave room for some great domains... wrathof.god, oh.god, iam.god... I wonder, though, if we'll see a Barring all else, I can't wait to see what the Christian/Catholic community has to say about this... Re:Pathetic... (Score:1) Or is sex an unnatural act? Or is there only one "God"? Not that any of this matters. You seem to be afraid of blasphemy (whatever that means) of some organized sort. It is a statistical certainty that others disagree with your definition of blasphemy, even to the point of deducing you as the blasphemer. Which party is right, and justified in their use of .god, and which party is wrong and unjustified" I always like to think of myself as being correct in every context, too, but whenever I get to feeling that way, some Christian or another comes along and disagrees with me. Feh. Welcome to the real world, where freedom still reigns and some folks are still able to draw their own conclusions. Even about God (or gods), and where He/She/It/they may shove it (or not). Enjoy it while it lasts, as I assure you that the alternative is markedly inferior. I want to register is.god.. (Score:5) Of course there are OTHER is.god subdomains.. anybody ELSE have good ones? =) .- CitizenC (User Info [slashdot.org]) Oh i DID!!! (Score:1) Re:Viva la Revolution! (Score:3) Who does this guy think he is? (Score:5) Well, who does he think he is? God? Re:DOES GOD HATE YOU? (Score:1) Anyway, please stop posting crap, Dr Fool. Gates.says.money.is.god Re:Too many TLD's (Score:1) No one really seems to have kept up the intent of the COM/ORG/NET division, so what the hell's the point. Or do you think -Earthman Re:Interesting (Score:1) Re:Alternate DNS... GOOD (Score:1) Viva la Revolution! (Score:5) I've said it once, and I'll say it again. Burn All TLDs!!! OK, I really, really am serious. We simply don't need them. Think about it. Companies will always buy their domain name with every possible TLD no matter how many there are. So it isn't like we'll get any more domain names appearing when we create more and more restrictive rules. Meanwhile, the trademark disputes won't stop. They'll just get more lucrative. What's the point of trying to pigeonhole every site by its Jungian archetype? TLDs like .gov can exist, certainly, but why make those last three letters so important? Let's just open it up. Anything should be allowed to be a TLD. If coke wants to buy .coke, then fine. We've grown out of this authoritarian need to control everything. Let's just let go, and reorganize at a higher level. Funny as it sounds Burn All TLDs is really what I think we need to do. Leave it ALL open for everyone. If slashdot wants .slashdot or .flame or .grits, what other than an anal need to organize everything should stop them? I get the feeling that, like all the other times I have said this, I'll either get moderated into the floor or ignored. But this really is an important thing to think about. We all assign some magic importance to it, but it is just an organizing convention from the prehistoric past. Arpanet is gone. Time for us to find our names for ourselves. Re:Alternate DNS... GOOD (Score:1) Re:I want to register is.god.. (Score:1) The Second Amendment Sisters [sas-aim.org] wouldn't (Score:1) hmmmm seems to me that would be about like crossing the proton streams. you know, dogs and cats, living together... tcd004 Here are my Microsoft [lostbrain.com] and AICN [lostbrain.com] parodies, where are yours? Re:Interesting (Score:2) will.of.god submission.to.god house.of.god -Steve Re:Viva la Revolution! (Score:1) Re:.odd (Score:1) hoosiers.for.jesus@christ.in.us What's next for TLDs? Re:Who would be stupid enough to buy these? (Score:1) Opportunity missed. (Score:2) Example: microsoft.isnotgod Re:Joe Baptista = nuts (Score:2) (Off-topic note to CmdrTaco et al.: Fix extrans mode or remove it!) availability checks (Score:1) more positive re-inforcement for my paranoia, now .god may be against me too. What do you mean? (Score:2) Re:Yet Another New TLD Proposal (Score:1) Nope, you're right, that's the guy. I've met him IRL (been to one of his parties, way back when), he's very ... interesting. This is my yes.yes.yes.oh.yes.oh.god (Score:3) Joe Baptista on MAPS RBL (Score:5) Policing responsibility? (Score:2) Taking it one step further- even if the site is a parody or direct rip-off of the trademark.. should the registrar really be held accountable rather than the owner? - Re:I want to register is.god.. (Score:3) why.god: While we're resistering companies, how about: Or advertise your prowess in programming: The solution. (Score:2) get working on new directory services for the web, start enforcing DNS registration policies, get How will having a cool domain suddenly make the content of your site worth something? It won't.. Who needs TLD's (Score:2) aech,tee,tee,pee,colon,slash,slash,doubleyou,doub come on how about just plain old shit! that would be much better, no http, no com, gov, net etc. Thanx, Re:DOES GOD HATE YOU? (Score:2) And all system backups must be done onto 5 1/4 floppies... Re:.odd (Score:2) Re:idiot (Score:2) Or perhaps instead of being an idiot, he is insightful. The domain of trademarks is commerce. (Damn overloaded language. Let me try that again...) The concept of "trademark" only exists in relevance to trades. It is logically impossible for a trademark to be violated outside of the scope of commerce. For example, when someone hands a mysteriously burned black rock to a geologist and the geologist says, "That is coke," he is not violating a trademark. I'm assuming that anything within the .god TLD is implicitly within the realm of religeon. (No, I don't truly and naively believe that's all it'll be used for, but the TLD nevertheless has a purpose, just as .com and .net do.) No religeon (except Scientology cough) could have a trademark, could it? Is the pope going to register a trademark on the word "Catholic"? What's next, copyrighting the bible? Yeah, we have to protect God's incentive to create such works. I'm an atheist have never witnessed anything supernatural in my life. But if a fiery chariot comes down from the heavens, bearing a being who says his name is "McDonalds", then I'll going to register and sing His praises on mcdonalds.god, and if any megacorp comes looking for me, I'll laugh in their face. This is out of your realm, Ronald! --- Re:Respecting Trademarks (Score:2) NOT THE UNITED STATES OF AMERICA --- In this case, it's both. Americans in America are supposed to obey American law, even if the effects of their actions cross national boundaries. ... Re:Opens up some humorous possibilities (Score:2) core is an independent registrar organization. whatthefuck.com is registered by one Nick Melnick of 2550 Long Lake Road, New Brighton, MN 55112. he registered it through domainbank.net, a core member. as soon as core popped up, i went and grabbed sickfuck.org, a domain i had long lusted for, but which my requests for had been previously denied. down with nsi. -- SnowPhoton's TLD Hut (Score:4) Today only, register your domain under the following TLDs: Each registration costs only $100. Get yours fast! note: this service does not cover anything other than adding your name to a list. Make your checks out to... So is the bottom level domain .devil? (Score:2) Re:I want to register is.god.. (Score:3) warez.god mp3.god napster.god dog.god 31337.god b1ff.god BoW.is.god/phear/BoW Bob.is.god/fnord/ pr0n.god Stranger than, er, fiction... (Score:2) This one's gonna be too good not to abuse. I can see it now -- atheist.god, i.am.god, $foo.is.god (with $foo as who/what ever), ask.god (hehe confessional! hahaha), find.god (aka 'where's waldo'), etc. The hilarity just may never end. But first, I've gotta get com.god. I must! hahahahaha Re:Viva la Revolution! (Score:2) Re:Offtopic rant (Score:2) You're suggesting that, when people are rude an offensive, I should just "deal with it?" I think not. Don't get me wrong here -- I'm not some crazy overly "PC" bastard. To hell with political correctness. There's a difference between trying to stop people from saying things that might be offensive, though, and asking them to stop saying things that are. You're right, meanings of words do change. And as it stands right now, "gay" means "homosexual." It does not mean "dumb" or "stupid." People insist on using it that way, though, and the end result is they end up offending people like me. And if you want to take an extremist view, they make the world an increasingly more hostile place in the eyes of gay kids, who hear these comments and think that everyone has something against them, for no good reason. Re:Cripes... (Score:2) The big question is (Score:3) Will atheist DNS admins accept it? Joe Baptista = nuts (Score:2) Sarcasm aside, this guy is 20 pounds of BS in a 10 pound sack. Maru Yet Another New TLD Proposal (Score:4) There have been several proposals for adding more TLDs - the IAHC International Ad-Hoc Committee was relatively reasonable, ICANN was a bit less so, thoguh that was partly because it was a year or two later so there was more commercial conflict, and Esther (bless her heart) knew it would be a dirty job when she took it. As far as I know, the only proposals for new TLDs that have actually succeeded have been a few new country codes (because there's an existing bureaucracy for that, plus of course the countries who've made a quick buck by renting out their namespace), and Brad Templeton's proposal for There have also been the disorganized proposals, from people like Kaspureff at Alternic, and the orange.net folks - start an alternative root, and try to convince people to use your root instead of the Big Roots, but they're fighting a losing game. It's partly a losing game because they've been losing (:-), and partly because it doesn't solve the fundamental problem, it just trashes any efficiencies you gain by shoving conflicting names down a layer in the tree so you don't see them if you're not looking for them. The people who've been successful at pushing new namespaces have taken different approaches - ICQ numbers are a global namespace, and nobody minds because they don't spell anything and the server can cope with the scale. Realnames sells namespace, and people who want it can use it. And all of these things can easily be patched under the DNS tree, e.g. 1234567678.icq.net or mycompanyname.realnames.com. (Unless I'm mixing up names,) Joe does, however, get Extra Slack points for having been the guy who tied up various Canadian provincial and federal government organizations for a while by constantly faxing them his requests for fair treatment, better laws and regulations, etc. You mean... (Score:2) Oh my! (Score:3) Isn't that actually how legal jibberish was created? (At least it's how I was taught in my school.) =) Pablo Nevares, "the freshmaker". Judy Blume's web site (Score:2) Cripes... (Score:5) If you want to do something really useful, modify gethostbyname() etc to use LDAP calls and set up an LDAP naming service. Re:I can't believe no one thought about (Score:3) WHOIS my.god (Score:4) dibs on... (Score:2) Re:Viva la Revolution! (Score:2) motherof.god (Score:2) or of course....my childhood favorite FluX After 16 years, MTV has finally completed its deevolution into the shiny things network Re:idiot (Score:2) 1. It was written by somebody else 2. It is really old As I already said, translations are different. As far as a GPL or BSD Bible I wonder if you really understand how offensive that is. The Bible is viewed by believers as Divinely inspired. You can change things around but then it is no longer the Bible, merely a book that bears a resemblence to the original. As for how peeved people can get, try looking up the history and responses to heresy. I'm not defending either side as Jesus is about love and fidelity to God not the auto de fe, but I suspect you didn't realize the extent of your flamebaiting. DB The registry wasn't linked above (Score:2) It's only a "test registry" at the moment, but it's got links to create/modify/whois. Pablo Nevares, "the freshmaker". Re:Viva la Revolution! (Score:2) Who's this "we" you refer to? Mankind? America? Slashdot? Solution to the DNS problem... (Score:3) [templetons.com] -p. Of course.... (Score:2) just ask jeez [modernhumorist.com] FluX After 16 years, MTV has finally completed its deevolution into the shiny things network Egos (Score:2) Somebody wants to be the god of their own little world, and have everybody know. What other reason is there for such a label? yeah, it's funny, in a way. It's also very disrespectful and presumtuous. It seems to mock the other names, and anybody who dares believe in higher powers. I'm not going to say 'No, there should be no I hope I've done the HTML right. Starskita Soon any 3 Letters will become a TLD (Score:2) .god is just another step. Who knows what TLD's will come next. . .	http://slashdot.org/story/00/05/18/2346226/god-domain-names-another-pioneer-registrar?sdsrc=next	CC-MAIN-2015-18	refinedweb	4,062	67.76
//Read data in a buffer, if nbChar is greater than the //maximum number of bytes available, it will return only the //bytes available. The function return -1 when nothing could //be read, the number of bytes actually read. int ReadData(char buffer, unsigned int nbChar); char buf = "0"; int num, i = 0; while( i < 5 ){ num = ard.ReadData( buf, 256 ); if( num == -1 ) { cout << "Nothing to read\n"; } else { cout << "Read: " << buf << endl; cout << "Num: " << num; break; } i++; Sleep(500); } where ard is the Serial class. ard.ReadData( buf, 256 ); char buf = "0"; Quotewhere ard is the Serial class.And we're supposed to guess how (and even if) you've opened the serial port, and to guess what you are currently seeing as output, and to then tell you what is wrong. I'll pass until I know more. Quoteard.ReadData( buf, 256 );You've told it that it can read up to 256 characters into buf, BUTQuotechar buf = "0";buf points to a string containing only one character and the null on the end.Pete Serial ard = Serial("COM4"); char buf; int length = 256; buf = ( char* ) malloc( length ); int num, i = 0; while( i < 5 ){ num = ard.ReadData( buf, 3 ); if( num == -1 ) { cout << "\nNothing to read"; } else { cout << "Read: "; for( int i = 0; i < num; i++ ) { cout << (buf + i); } cout << "Num chars: " << num; break; } i++; Sleep(500); } Which seems to work now, char buf[256]; You are allocating memory, but not freeing it.Why not use a static array?Code: [Select]char buf[256]; #include <cstdlib>#include <iostream>#include "SerialClass.h"using namespace std;void readData();Serial ard = Serial("COM4");int main(){ if( ard.IsConnected() == true ) { cout << "Done" << endl; } else { cout << "Connection failed, exitting"; return EXIT_FAILURE; } //test arduino connection if( ard.WriteData( "1", 1 ) == true ) { cout << "Data sent successfully\n"; } else { cout << "Data not sent"; } readData(); ard.WriteData( "0", 1 ); readData(); ard.~Serial(); // Keep the console open to check output. // Saves from using a breakpoint Sleep(20000); return EXIT_SUCCESS;}void readData(){ // Check for data coming from arduino // If no data is found check 4 more times char buf; int length = 256; buf = ( char* ) malloc( length ); int num, i = 0; while( i < 5 ){ num = ard.ReadData( buf, length ); if( num == -1 ) { cout << "\nNothing to read"; } else { cout << "Read: "; for( int i = 0; i < num; i++ ) { cout << *(buf + i); } cout << "Num: " << num << endl; break; } i++; Sleep(25); } free( buf );} ard.~Serial(); Please enter a valid email to subscribe We need to confirm your email address. To complete the subscription, please click the link in the Thank you for subscribing! Arduino via Egeo 16 Torino, 10131 Italy	http://forum.arduino.cc/index.php?topic=143611.msg1079162	CC-MAIN-2016-30	refinedweb	437	70.02
Building Immersive Apps Using The Mixed Reality Toolkit Editor's note: The following post was written by Windows Development MVP Senthamil Selvan as part of our Technical Tuesday series. Danae Aguilar of the MVP Award Blog Technical Committee served as the technical reviewer for this piece. With the release of the Fall Creator Update (FCU) for Windows 10, Microsoft is entering into the Mixed Reality market. In this article, we’ll delve into how to start programming for Mixed Reality in Windows 10 - but first, make sure you have all the tools needed to build apps in Windows by following this link. You can now download the FCU for the Windows 10 by following the steps here. Let’s get started! I strongly recommend looking through the contents of this link, in order to setup the machine and Unity environment to be able to start the programming. Step 1: Installation Install the required software for the development machine: Step 2: Download the Mixed Reality ToolKit from the GitHub Download the full toolkit and unzip it to the local machine. In this case, we unzipped it to C:\Mixed Reality. The photo below shows the folder structure after unzipping: Step 3: Export Package Open the Unity application. In the startup screen, select the Open option on top right. Select the folder belonging to the Mixed Reality Toolkit, which was unzipped in previous step. Wait for Unity to load all the Assets. Once the Unity is loaded, go to the Assets folder from Project tab. In the Asset menu on top, select Export Package. Export it as a MixedReality package to any folder you want to use. Next, close the Unity and return to the MixedReality export package folder. Now we have the ready made package with all the prefab, scripts and the animation for the Unity to start programming. Start the Mixed Reality App Programming Open the Unity application and click on New to create the new project. Make sure you select the 3d option in the New window. Once the Unity is loaded, import the Mixed Reality package, which was exported in step 2. Next, we’ll go through the following sequence - Assets -> Import Package -> Custom Package. In the window, select the Mixed Reality package. Once the package is imported you will now see the Mixed Reality Toolkit in the menu option of the Unity Editor. Now select the Mixed Reality Menu. Go to Configure and select Apply Mixed Reality Project Settings In the Apply Mixed Reality Project Settings check all that applies. Make sure Target Occluded Devices is checked. Click on Apply to apply the settings. Now select the Mixed Reality Toolkit->Configure-> Apply Mixed Reality Scene Settings Click on Apply to apply the scene for the Mixed Reality. In this sample app, we are going to capture the Gaze and the Gesture input to manipulate the 3D object. The input tap event is handled to throw a ball with the force. The ball is thrown at the sphere or cube which is placed in front of the camera. Create the 3D objects 1. Create the 3D object Cube and set the below values. Rename the cube to Player1 2. Create the 3D sphere and set the X=-0.3, Z=5.916 and Y=0.51 in the Position. Rename the sphere to Player2 3. Create Plane and apply the below settings 4. Create a Material with your color and apply the material to both cube and ball. 5. In my case, I created a ColorMaterial with color blue, which is applied to Cube and Ball. I applied the colour grey to the PlaneMaterial. 6. Select the Cube, and Add Component on right panel and type Rigidbody. Select the Rigidbody to be added. This will give the gravity to the object, to behave like a real ball or cube. The final setup will look like the below: Gaze Input Now we are going to handle the Gaze input and change the color of Player1 and Player2. When the user inputs Gaze for Player1 (cube), its color will be changed to red. - Select the Assets folder from the Project tab in Unity Editor. - In the Assets folder on right panel, right click and create C# Script. - Name the script GazeAtObject.cs - Once the script is created, double click on that to launch Visual Studio. This will open the C# file and make it ready for coding. - Add the below code to the cs file using System.Collections; using System.Collections.Generic; using UnityEngine; public class GazeAtObject : MonoBehaviour { private Color original; // Use this for initialization void Start() { var cube = this.GetComponent(); original = cube.material.color; } // Update is called once per frame void Update() { } void OnSelect() { var cube = this.GetComponent(); cube.material.color = Color.red; } void OnReset() { var cube = this.GetComponent(); cube.material.color = original; } } - Select the Player1 from the hierarchy and from the Asset drag the script GazeAtObject.cs and drop it on the right panel. - Select the Player2 from the hierarchy and from the Asset drag the script GazeAtObject.cs and drop it on the right panel. Basically, the above code will change color when an OnSelect method is triggered, and the color is set back to original OnReset method. Handling the Input Now we need to handle the Gaze input and call the OnSelect and OnReset method on it. On the Asset folder search for Cursor.cs. You can also locate the cursor.cs under Assets->HoloToolkit->Input->Scripts->Cursor folder Now double click to open the cursor.cs file in the visual studio. Locate the OnPointerSpecificFocusChanged and add the below code at the end of the event. if (oldFocusedObject != null && oldFocusedObject.name == "Player1") { oldFocusedObject.SendMessage("OnReset"); } The full function will look like the below: protected virtual void OnPointerSpecificFocusChanged(IPointingSource pointer, GameObject oldFocusedObject, GameObject newFocusedObject) { if (pointer == Pointer) { TargetedObject = newFocusedObject; CursorModifier newModifier = (newFocusedObject == null) ? null : newFocusedObject.GetComponent(); OnActiveModifier(newModifier); } // my code here if (oldFocusedObject != null && oldFocusedObject.name == "Player1") { oldFocusedObject.SendMessage("OnReset"); } } Now locate the UpdateCursorTransform function and add the below code in the first else statement. //my code here TargetedObject = newTargetedObject; if (TargetedObject.name == "Player1") { //Debug.Log("selected"); TargetedObject.SendMessage("OnSelect"); } Again, the full function will look like below: protected virtual void UpdateCursorTransform() { FocusDetails focusDetails = FocusManager.Instance.GetFocusDetails(Pointer); GameObject newTargetedObject = focusDetails.Object; // Get the forward vector looking back along the pointing ray. Vector3 lookForward = -Pointer.Ray.direction; // Normalize scale on before update targetScale = Vector3.one; // If no game object is hit, put the cursor at the default distance if (newTargetedObject == null) { TargetedObject = null; TargetedCursorModifier = null; targetPosition = Pointer.Ray.origin + Pointer.Ray.direction * DefaultCursorDistance; targetRotation = lookForward.magnitude > 0 ? Quaternion.LookRotation(lookForward, Vector3.up) : transform.rotation; } else { // Update currently targeted object //my code here TargetedObject = newTargetedObject;<br> if (TargetedObject.name == "Player1")<br> {<br> //Debug.Log("selected");<br> TargetedObject.SendMessage("OnSelect");<br> } if (TargetedCursorModifier != null) { TargetedCursorModifier.GetModifiedTransform(this, out targetPosition, out targetRotation, out targetScale); } else { // If no modifier is on the target, just use the hit result to set cursor position targetPosition = focusDetails.Point + (lookForward * SurfaceCursorDistance); Vector3 lookRotation = Vector3.Slerp(focusDetails.Normal, lookForward, LookRotationBlend); targetRotation = Quaternion.LookRotation(lookRotation == Vector3.zero ? lookForward : lookRotation, Vector3.up); } } float deltaTime = UseUnscaledTime ? Time.unscaledDeltaTime : Time.deltaTime; // Use the lerp times to blend the position to the target position transform.position = Vector3.Lerp(transform.position, targetPosition, deltaTime / PositionLerpTime); transform.localScale = Vector3.Lerp(transform.localScale, targetScale, deltaTime / ScaleLerpTime); transform.rotation = Quaternion.Lerp(transform.rotation, targetRotation, deltaTime / RotationLerpTime); } Save the code and close the Visual Studio. Next, go to Unity Editor and Run the project. You will notice that the cube called Player1 will change its color to red. Right click to move around the mouse, and change the color of the player1. When the Gaze is out of the Player1, the color will be original color - otherwise, it will be red. Handling Tap / Input Click Event Now we going to add a Tap event to the app. By taping at the gaze object, we going to shoot a bullet at it. The bullet will be a small sphere with a force added to it. The forward direction will be calculated based on the camera forward look. - Go to the Cursor.cs again and double click to open it in Visual Studio - Locate the OnInputClicked event in the cs file - Copy paste the full code from below to the function public virtual void OnInputClicked(InputClickedEventData eventData) { // Open input socket for other cool stuff... var ball = GameObject.CreatePrimitive(PrimitiveType.Sphere); ball.transform.localScale = new Vector3(0.1f, 0.1f, 0.1f); var rigid = ball.AddComponent(); rigid.mass = 0.5f; var trans = MixedRealityCameraManager.Instance.transform; rigid.position = trans.position; var transformed = trans.forward; transformed = Quaternion.AngleAxis(-10, trans.right) * transformed; rigid.AddForce(transformed * 500f); Debug.Log("Input Transformed"); } In the above code, we are creating the sphere at run time and setting it size to small. Then, we’re adding force to throw in a forward direction. Save and close Visual Studio. Now run the app in the Unity Editor. To throw the spheres, tap (left mouse click) while holding down the Shift Key. To move around, hold the right mouse down. Running the code on Emulator Windows 10 FCU comes with the Mixed Reality portal for testing the app in the emulator. Go to settings to enable the developer mode, and then enable Mixed Reality Follow this link here to setup the portal: Run the Mixed Reality Portal and enable the headset from the For Developer option Once enabled, the Mixed Reality will be executed. Once the Portal is running, now go back to Unity Editor and run the project. This time it will execute inside the Mixed Reality portal and also in Unity. You can see it in both places. Play around and enjoy! Senthamil Selvan is a Windows Development MVP. He has published several apps to the windows store. He is passionate about Microsoft Apps and HoloLens development. Microsoft SharePoint is his profession, and App development is his passion. Follow him on Twitter @altfo.	https://docs.microsoft.com/en-us/archive/blogs/mvpawardprogram/immersive-apps-mr-toolkit	CC-MAIN-2020-16	refinedweb	1,657	51.14
- is that when I make "fist" posts like that, mine get deleted with a nasty note from Alex. Admin This is the standard practice for the Win32 API. Getting it wrong is also apparently standard practice (e.g. the registry functions on Win95 that always reported the size in 1-byte characters but actually copied data in 2-byte characters or vice versa). It's somewhat efficient if you guess correctly, and if you guess incorrectly, well, that will get caught by QA before the product ships. ;-) Admin I could go into the Whole Spiel ™ (memory pointers, correct spellings) but I'll just cut to the chase: The answer is 4. Admin TCHARs are decided at compile time in C++. If you pass a char* to GetTempPathW, the compiler will complain. Therefore, since there is no cast to wchar_t, I assume UNICODE is not defined. Therefore, no buffer double overrun. Just the main overrun of "If path is larger than my buffer, write past the end of the buffer anyway, thereby bypassing any security Windows tries to offer me (and people will blame Microsoft for security holes. BWA HA HAH HA HAAAaaaaaa....)" followed by the lack of a smart pointer for exception safety. Admin As Joel from JoelOnSoftware says, he tests applicants on two fundamentals: 1) recursion, and 2) pointers. Recursion isn't so useful in the real world, but understanding it and understanding indirection via pointers reveals a sort of comprehension that is required for effective programming -- especially at a low level. On the other hand, lots of programming is done at a higher level ... where these modes of thinking are perhaps not so crucial? Admin Good spot. And the answer is "NO" #include <Windows.h> #include <stdio.h> int main(int argc, char argv){ char buff[1]; int i=GetTempPath(1,buff); printf("Try 1 %d\n",i); SetEnvironmentVariable("TMP","c:\\"); i=GetTempPath(1,buff); printf("Try 2 %d\n",i); return 1; } Try 1 32 Try 2 4 Need a while loop to get a temporary directory? WTF! Rich Admin The Real WTF is that the guy uses the MFC instead of STL. Admin There's a third error - it doesn't handle the case where GetTempPath fails and returns 0. In this case it returns a string containing whatever random bytes were in the allocated char block. Admin Admin The whole TCHAR -vs-char-vs-wchar_t thing is not really all that important - unless you specifically specify a Unicode build, using a standard char with this function is perfectly fine because GetTempPath(...) will resolve to GetTempPathA(...). Just because code is not TCHAR-capable does NOT mean that it is incorrect. That is what allows older Windows 3.1-era code to compile and still work correctly without changing the code to be TCHAR capable. Writing TCHAR-capable code helps mostly when you have to make both Unicode and ANSI builds from the same codebase. As far as the code itself, the first call to GetTempPath(...) should not cause a overrun because the function is bounded by the length passed to it. At worst, it would just not put a terminating NUL into the buffer (assuming that the buffer really is 256 characters long). The length value passed to GetTempPath(...) is specified in characters, not chars, so passing a value that is (length sizeof( TCHAR )) is incorrect - it will pass the wrong buffer length in a Unicode build. Regardless of using TCHAR, char or wchar_t, the buffer is still 256 elements long. (There are some Win32 functions that expect a character/element size, and others that expect a byte-size.) AFAIAC, the WTF here is the use/abuse of dynamically allocated memory. There is likely more then enough stack available to create a buffer of __MAX_PATH length on the buffer (n.b __MAX_PATH includes space for the terminating NUL character). So it is much faster to just get that buffer from the stack and pass it in instead of dynamically allocating the memory. It is also much faster than calling the function twice! A previous poster was worried about [the overhead of] "copying the memory twice", but it takes much more time and instructions to hit the function once to determine the required length, hit the heap to allocate the required memory (+1 for the NUL), call the function a second time, and then deallocate the allocated memory. Stick to the stack for little memory requirements like this - there is no need to complicate things and no need for additional handling of new failures - if the stack could not handle the request, you would not even get to that part of the code. Also, when dealing with multithreaded code, code that abuses the heap like this kills performance (when using the default shared heap). Using __MAX_PATH as the buffer size here is correct - this particular function cannot handle extended filename syntax, and as a general rule, only the wide (Unicode) versions of functions are capable if handling them, so you know that the function will not be trying to hand you more than __MAX_PATH characters. CString abuse is a whole other problem but not one that is specific to this code... Lots of MFC developers abuse CString due to ignorance of how they really work. I would have written the function much simpler as:The memory management is passed to the caller - if they want it in a CString, they can manage the CString and pass me its buffer and size. If not, they can pass me a buffer allocated however the hell they needed it allocated. Stack, Heap, Shared Memory Segment, Memory Mapped File, etc. - it does it matter, the function just works for all of them. It can also be used in a MFC or non-MFC build, Unicode or ANSI. If the function succeeds, the return value will be ERROR_SUCCESS; if not, it will be a valid Win32 error code - just what the caller needs to figure out if something went wrong and if so, exactly what did go wrong.The amount of data copied into the buffer (if any) is returned via reference, to optimize further manipulation of the data by the caller, but can safely be ignored in most cases.Of course, this is a very thin wrapper around the function, so I would have removed it completely and had the developer call the function directly and not through a poorly designed and written minimal wrapper function.As usual, exception handling needs to be done by the caller, because the callee (in this case) does not have enough information, not is complex enough, to react intelligently to any exceptions. Peace! Admin Darwin? Stupid little children... Admin Your mastery of the non-sequitor* is breathtaking. But, you're still wrong. That means it doesn't really support your argument. [image] As for the TCHAR stuff: I wasn't saying that his example was wrong because it didn't use TCHAR, but I don't think it makes any sense to make use of it in some places and not others. (see the retval string length calculation) Not using it at all and not defining UNICODE or _UNICODE is fine, but using char and defining them makes for more potential errors than are necessary. Admin Um, no. You hand it a char[] that sits on the stack. If it's too small, allocate one on the heap and use that. It works pretty well in the common case and works in the general case. Admin Admin You are correct. I was weened before there were TCHARs, I'm not used to it. =) The reason you need a return string is because the interface is returning a CString by value. I wasn't going to take the liberty of changing the interface, but if I did I would pass an input CString by ref as an earlier poster showed. Admin The interface "const T* foo(...)" where the return value of foo is NULL on failure and something read-only on success allows implementations to do the minimum possible amount of work in cases where the implementation already has the data in memory in an appropriate format. For example, getenv() returns a char * to the environment variable memory of the process. No string copying, no memory allocation of any kind is required to implement the interface if the implementation already has the appropriate character strings handy (and if it doesn't, the implementation is best suited to determine buffer lengths and so forth so it can dynamically allocate memory). Of course the pointer becomes invalid if you modify the environment, but if your application is asynchronously reading and modifying environment variables in multiple threads then you've got a WTF on your hands already, and if you really need persistent access to the data you should make your own copy of it. gethostbyname returns pointers into internal cache structures that were already allocated in the process of processing the response to a DNS request. If your application has multiple threads asynchronously resolving host names...uhhh...wait, that's a fairly normal case. At least there's the GNU extension gethostbyname_r...and gethostbyname2_r...ok, bad example. Well, there's getnameinfo...which tells you that the buffers are too small but not how big they should be...a binary search should suffice...no, it's still a bad example. localtime...uhhh...ok, there's just no excuse for localtime. It uses a data structure of static length to return values based on a user-supplied parameter. The only possible implementation cost savings would be if localtime(NULL) was equivalent to "get the current system time" and returned you a buffer to shared memory in the OS that pointed directly to the registers of some kind of clock chip which happened to have exactly the same layout as struct tm (or vice versa). Or maybe your CPU uses some strange memory architecture like segmented address spaces with different segments accessed at different speeds, where you might want to put latency-sensitive data like time data in memory with a faster access path. Or maybe your library has hand-optimized assembler code that uses hardcoded addresses for speed while doing DST calculations to a resolution of one-second. Note that localtime_r relies on the caller to provide the buffer, so it's not like localtime saves a memory allocation relative to localtime_r. There's just no excuse. Admin Um, I think it's a fair guess that the whole point of the function is to have a wrapper around GetTempPath that returns a CString. Because quite frankly, your wrapper adds nothing to the function except a different error handling strategy - laudable, perhaps, but not exactly the point. Admin Read the docs again. It says that if the temp path fits inside the buffer, it returns the length of the string (without null). If it does NOT fit inside the buffer, it returns how many characters are needed for the buffer (including null). If it returns 300, you pass in a 301, it will now return 299. Try it out. Admin Well, what happens if the CString constructor throws an exception? Better to use a smart pointer for instead of a raw char * for path. Admin No, it returns the size of the buffer required. It only returns the length of the string if it fits in the buffer. So if the path is c:\ and the buffer you pass it is 2 bytes, it returns 4 If the buffer you pass it is 6 bytes, it returns 3. Rich Admin The problem was I had misread your code. I was reading "char pStr = retval.GetBufferSetLength ((pathlen+1) sizeof (TCHAR));" as "char pStr = new char[something something retval((pathlen+1) sizeof (TCHAR))];" or something equally silly. I missed that you got rid of the new and were just setting the CString buffer size directly. Admin The ahem real WTF here is that two pages of posts into it, no one has yet to suggest checking the return value of new and properly handling our of memory counditions instead of just crashing. Admin I was wondering if someone would mention that. Does anyone actually check the return value of new? I know we "should", but I have yet to see production code that does so that wasn't intended to run within a very memory limited environment. Captcha: STFU. Priceless. Admin ERROR_SUCCESS? WTF! (Yes I'm sure that's correct -- but I don't want to know.) Admin If you don't have a good escape plan you're boned anyway. In much code, even if a few functions can handle an out of memory error, the whole thing may come down because of something further up the stack. Now, if you're writing something more important than regular desktop apps, you're going to need a lot better justification than that, but I hope that most of us aren't writing heart monitor firmware or anything like that. Admin That is my whole point - the entire function is a WTF. Putting a CString wrapper around a simple function like this smacks of a newbie MFC developer. Doing multiple dynamic memory allocations is just icing on the cake. Forcing a particular memory management method, regardless of returning a raw pointer or hiding the memory management behind a higher-level class, is always a bad idea. This is exactly what the original code did - it forced the use of a CString. Sometimes this kind of "forcing" is unavoidable or even required, but not in this case. For something as trivial as wrapping a call to GetTempPath(...), it is just plain stupid. My version can work with any memory, regardless of how it was allocated. As you more away from trivial single-threaded applications and start taking advantage of modern real multi-CPU (and even fake ones like a HyperThreaded core) you start to give serious thought to how a simple misuse of dynamically allocated memory can bottleneck your code to a single-thread. The solution is not to avoid it in all situations, but to allow the caller (who has more knowledge of the particular situation at hand) to manage the memory as required. My wrapper was thin for two reasons - (1) to show that using new here is serious overkill (on the level of shotgun vs. fly), and (2) that the wrapper is pretty much useless in the first place - I even mention that I would just have gotten rid of the wrapper entirely. Peace! Admin Heh... It is not as bad as it sounds - all of the standard Win32 Error Codes start with ERROR_. Kinda like some people name all of their status constants by starting them with STATUS_ (STATUS_FAIL, STATUS_OK, STATUS_MAF, etc.). Nothing to see here, carry on... :P Peace! Admin A conforming implementation will never return NULL from a 'new' operation and will instead throw an exception (std::bad_alloc, I think, but it's been a while). Admin I did. Kinda... I just avoid the entire situation in the first place by not using new at all. In the CString version of my function, an exception would get thrown that would be handled by the caller - I would not be able to do much with it, anyway. Oh, and an as aside, in my "real" code, I always check pointers that are (1) passed to me, two (2) after I allocate into them. It is part of my coding standards, in fact. My apps still have bugs and issues, of course, but rarely due to NULL pointers. Getting passed invalid pointers is another issue entirely, and I know of not a single case where all non-NULL pointers are validated at runtime (e.g. IsBadWritePtr(...) on Win32) - the checks just take too long. Peace! Admin Of course they do. Not all systems can afford the the initial overhead of garbage collector overhead of Lisp, Smalltalk, or Java. And even those that can afford it still have operating systems that are written in C/C++/Pascal/Assembler, where these issues still are important. Or maybe the real WTF is that there are people who still think that everyone who doesn't follow their own way of doing things is wrong. Admin Not to mention run the risk of corrupting your address space. The first rule of checking for valid pointers is: don't. Admin Why not just do this: char path [MAX_PATH + 1]; Then none of that ugly dynamic memory allocation has to be used. Though there's a drawback that your stack has to be large enough. Though I guess most Windows programmers don't care about either. Admin Admin You can achieve some hideous WTFs in Java or C# if you imagine that "no pointers but has garbage collection" is a substitute for knowing how they handle passing objects to functions and understanding the subtlties of how the garbage collector actually works. There's huge flaws in C++ and many many good things about <insert your language of choice here> - but the real WTF is a belief that any computer language that lacks a sentient telepathic AI module in the compiler will somehow eliminate the need for actual thinking and knowledge. If that guy put as much effort into learning Java or C# or Lisp as he put into learning C++ then he'ld still have been able to come up with something to suit this site. Admin Don't use IsBadWritePtr. Here's a real-life lesson on why not. Or, go straight to the source and learn from Raymond himself. Admin Why bother with the check? Everyone knows that MAX_PATH characters are enough for every string in the universe. Admin Not necessarily. It's a sign that the industry is maturing and with better, more appropriate tools for the task (i.e. high level languages that hide the notion of pointers to the programmer, a la java, .net, VB) when designing and implementing business application allow the programmer to focus on the business rules he/she implements versus allocating, checking, freeing, locking, unlocking, tracking every little bit of buffer they need. Different languages are good for different tasks. I would be happy to write device driver code* or low level application protocols over TCP in C or C++. I would be less happy to build a GUI front end w/ database access with these languages. I personally like C# for the syntax, power (and being lazy, visual studio) and you're always one unsafe away from messing up with real pointers. It's the best of both world. * I don't write device drivers for a living, just for fun. captcha: tango? uh? Admin Nice try, but there's another potential memory leak here. (This illustrates nicely, by the way, why that garage sale book on C is pretty useless when you're trying to write C++.) Admin You're thinking of malloc. In C++ you never need to check the return value of new. Admin This is not true by default for Visual C++ (which is the most widely used dialect) I don't see it. After reviewing the C++ draft, I'm pretty sure the sequence goes like this: Where am I going wrong? Admin You do if you disable exceptions in the compiler. This is commonly done for performance reasons, especially on embedded systems. Admin the problems are a memory leek and a buffer overflow. There is also another problem which realy isn't a problem, it more an effeincy problem. it the returmn type it's not a pointer(ie. the object is made twice). if (pathLen > 256){ /iff line executes it will always cause an exception(or a segmentation fault) pathLen = GetTempPath(pathLen, path); } There is acturaly nothing wrong with what he was doing i.e GetTempPath if GetTempPath does not have enougth space to return the path. then it returns the space required. I guess that this was done either when he was pissed or at done very early in the morning(i.e 3AM) the fix would be Admin Sorry I just realized i forgot to return NULL when an error has occured <font face="Lucida Console">CString * GetTempDirectory() { char* path = new char[65536]; CString *ret; int pathLen = GetTempPath(65536, path); if (pathLen > 65536){ printf ("GetTempPath failed with error %d. ", </font><font face="Lucida Console"> GetLastError()); return NULL; } ret = new CString(path); delete path; return ret;</font> <font face="Lucida Console">}</font> <font face="Lucida Console"></font> Admin You do not need the +1 for _MAX_PATH - _MAX_PATH already includes space for the NUL terminator. And since you are using the ANSI version of the function, you can be pretty certain that it is not capable of returning a path longer than _MAX_PATH, anyway. Extended filename syntax, and thus paths longer than _MAX_PATH, are generally not avaialble with the ANSI versions of Win32 functions. As far as the stack goes, I have never blown a stack doing small alocations like this in non-recursive scenarios, and by default the stack in Win32 is 1MB (adjustable via linker options). Of course, I am not doing embedded development now so..... :) If you are that worried about the stack, you can always dynamically allocate from the stack using alloca(...), although its availability is limited. The benefit of using alloca(...) instead of normal stack variables is that with normal stack variables, you will blow the stack upon entry to the function if the automatic variables exceed the available stack - none of your code will even run, but if you use alloca(...), the exception gets through at the point where alloca(...) is called, so you can put a try/catch around it and react accordingly. When used like this, you are able to "test the stack" to get memory and if the stack space is unavailable, resort to heap allocation. Tricky yes, but available nevertheless. Peace! Admin OK - where to start? :) First, you will never get a path that long from GetTempPath(...), especially the ANSI version (which is being used in this case). A buffer the size of _MAX_PATH will work well, and it does not have to come from the heap. In fact, the largest path that can be handled by the Unicode versions of Win32 functions is much closer to 32KB than 64KB. Please do not ever put that code like that into production. You are invoking multiple heap hits (both directly and indirectly), each one a possible failure point, without any error handling. These are also potential points that can serialize a multi-threaded application (if the heap is being abused here, it likely is elsewhere in the application). The checking of the return value is incorrect - the function returns zero for failure. Since the function is designed to tell you the required buffer size when you specify a buffer length that is too small, that is considered a successful return from the function - it did what it was designed to do: it successfully told you that you needed more buffer space. Reporting failures via the console is fine - just make sure that you have a console in the first place so that your message actually goes somewhere. The delete operator is incorrect, although (IME) this is benign in cases using simple types like this. Replacing WTF-ed code with code that is more WTF-ed might not be such a good idea... :) Peace! Admin quote from. Maybe 64 KB is a bit to big. Admin If the CString constructor throws an exception, the temporary is not destroyed. Yes, it's subtle, but these things are important. 99.99% of the time, there's no reason to write a manual delete or delete[] in C++. Use a smart container instead. Admin It was true of Visual C++ 6.0, which was one of the reasons why it was every C++ developer's least favourite legacy compiler for many years. The behaviour was incorrect, and would even crash the version of the STL that shipped with the compiler under low-memory conditions. It's been fixed. Admin In which case you're not programming in C++. You're programming in a related dialect. There's embedded systems and there's embedded systems. If space is at a premium and you have to scrounge every byte, then yes, you often can't justify the cost of exception tables. But in that situation, you've probably got specialised operator new implementations anyway. Larger embedded systems (I'm thinking MRI scanner-sized embedded systems here) often use exceptions freely. I think the chance that you'll need to call GetTempPath in your pacemaker code is pretty slim, though. If you're ever working on a project that implements something like that on a Win32 platform, please submit your story to The Daily WTF. Admin That's not really a problem. Firstly, CString is ref-counted which makes it cheap to copy. Copying it doesn't do a memory allocation. (This is one of many reasons to prefer it over std::string.) Secondly, a good compiler (eg VC8) will optimise away the copy anyway.	https://thedailywtf.com/articles/comments/Investment_Advice/2	CC-MAIN-2019-13	refinedweb	4,187	62.48
Excerpts 2006 - 2019 This page contains excerpts of blog posts relating to “made” stuff from the 2006-2019 archives. Wi-Fi Nixie Clock February 24th, 2018. How cool is it to be able to ssh to your Nixie clock via wi-fi ? The answer is that it is really cool. You can even run gcc on this clock and turn it into something else than a clock :) I plan on making a limited run of these and make them available in kit form. Including tubes, high voltage supply, PCB, Raspberry Pi Zero W, and all the components you will need in order to build your own Nixie clock. Laser cut supergun If you love arcade games, but don’t have the space or budget for a full sized arcade cabinet, a supergun together with a few arcade PCBs will satisfy most retrogaming needs. September 11th, 2017 Laser cut Wimshurst Machine Hackheim finally managed to fund a wimshurst generator cutting machine (laser cutter). With the date for Trondheim Maker Faire closing in, I decided to give it a spin. IN-2 module prototypes Scaling up Not quite happy with the first iteration, I decided to make a new version of the Götterdämmerung. This time, I published everything on GitHub. I was quite flattered when I recevied an email from Max Nijpels, who had actually attempted my build. Not only that, but he had built it bigger and also improved upon the one part that I still wasn’t quite happy with. Namely the Z-axis drive. A world first ? The BBC micro:bit was released on January 1st 2016. I decided to get my hand on one (ok, I nicked it from a stash of micro:bits at work) and see how far you could push the hardware. Turned out you could push it pretty far, but in the end, I had to interface an external gyro to get my balance bot working. I guess that stepper motors aren’t quite ideal for this purpose, but I used what I already had lying around, together with some 3D printed parts to hold everything together. Game room Another test print Behold: The Mobile Beer Platform! (Another solution to the Theo Jansen linkage) Startup The mission: Revive pinball in Trondheim. I recevied a request for pinball machines from a near perfect location and decided to give it a go together with cofounder Øyvind Møll. PopBumper AS was born and we are still in business :) We’re currently operating 12 pinball machines at Work-Work in Trondheim. Generative jewellery I have been fascinated by generative designs since I first read “Evolutionary Art and Computers”, by Stephen Todd and William Latham. I decided to give it a try :) I even got a call from a freelance journalist looking for material for Make Magazine, asking for high resolution photographs of this pendant, but it never appeared in the print edition. City Beest At the time, I was really proud of having made this thing, the machine that made it and the code that calculated the linkage parameters. However - it landed me in a world of pain when people wanted to see it live. The beest walked and the sensors functioned decently in a quiet indoor environment on a flat surface, but the sensor crapped out in noisy environments. The legs locked up if even a single one of the hundreds of nuts were too tight, and the battery pack (consisting of subjectively a gazillion NiMH cells) lasted 10 minutes on a good day - before requiring hours of recharge. Still, it won me a trip to the Rome Maker Faire - which was quite an experience. The beest is now retired and spends its days in a cage at the makerspace at the Norwegian Museum of Science and Technology. I just hope that they let it out once in a while and that the kids enjoy it :) Narcissistic tendencies 2.0 Ornithopters After having watched more than a few videos of japanese ornithopters, I decided to attempt a 3D printed version of an ornithopter. I quickly learned that PLA plastic is way to heavy for this type of design, but it was a fun attempt. Götterdämmerung “Test print” This was printed in order to demonstrate the capabilities of the Götterdämmerung 3D Printer. It’s big. Really, really big. It is also my entry for Trondheim Maker Faire 2015 Theo Jansen’s Linkage I decided to find out if I could find other solutions to the famous Theo Jansen linkage. This was a really nice excuse to finally implement a genetic algorithm - a few decades after they went out of fashion… Cigars Pumpkinhead 5.0 Götterdämmerung June 28th, 2014. This was my first attempt at designing a 3D printer from scratch. It’s harder than you think :) Cavendish Funhouse plafyield swap January 26th, 2014. I paid the quivalent of 300 USD for my Funhouse pinball machine at an estate sale many years ago. This was ridiculously cheap, but on the other hand, the machine had seen better days. It was dirty. The playfield had lots of wear and the cabinet paint was chipped. The machine was complete, but it really needed a new playfield. Fortunately, the guys over at Illinois Pinball Company had plans to make repro playfields for Funhouse. A local distributor called me up (knowing that I had a Funhouse) and asked me if I was willing to strip down my playfield and send it off to the IPB, in order for them to use it to calibrate their CNC equipment. I agreed - and received a factory fresh playfield in return - free of charge - a few years later.) Reassembly was nerve-racking. The playfield wasn’t dimpled from the factory, so I had to drill it myself. One wrong move and I would have ruined a 1000 USD playfield. Snus Narcissistic tendencies Piratebox Addicted Spar 7 (Pajazzo) replacement board Another TV-B-Gone booster Xenobird 2 3D printed vacuum pump This is a 3D printed version of a water jet vacuum pump. It operates on the principle that the combined dynamic and static pressure in the same flow is constant. The theoretic limit for this device is the vapour pressure of water. Strangely enough, this simple device was my biggest hit on Thingiverse (I decided to remove all my designs from Thingiverse in protest against a lawsuit that MakerBot had filed against another company at the time. I left a note indicating the reason why. Thingiverse later decided to censor (“moderate - due to missing STLs”) dissidents.) I am no longer an active user of Thingiverse, but the ghosts of my early projects still remains there. Open Source Modular Coil Gun May 23rd, 2012. My electronics skills are improving. Just finished my multi stage electronic launcher, having put my latest fabrication toy to the test. This device is lethal, but maybe not in the way you would expect from an electric multi stage gun :) Koi pond 1.0 Fabricating stuff that shouldn’t exist. 3D Printed an algorithmically created object. No humans involved. Designed using (Latham inspired ?) algorithms in Neurosystems’ Substance 3D software suite. Thing-O-Matic October 16th, 2011. Spent way too much money on importing a ridiculously expensive plywood-kit from Makerbot. The future is here. Yay. Pumpkinhead 4.0 Discovered Mandelbulber. Made a video. August 20th, 2011. Quite proud of this one actually. Had three machines running for several days, rendering the required keyframes before stiching the video together. Pumpkinhead 3.0 Old School. Made almond and chocolate covered marzipan cookies today - based on a recipe from Nostradamus. Had a hard time sourcing rose water, but succeeded eventually. Parametric speakers. The math behind this made my head hurt. The sound made my ears bleed. At some point molten metal emerged at the mosfet heat sinks. Seriously - I still have a constant ringing in my ears years later. Machine tweet Influence machine Got my hands on an old electrostatic generator, produced in Bergen, Norway by “C.Monsen”. All the sectors were missing and the disks were badly warped. I machined some parts that were missing from “Sustarin C” and created new disks from bakelite sheet. This is probably not the correct material, but it was the most rigid stuff I could find. After having done some research, I figured out the correct wiring and configuration of the pick up and neutralizer terminals. It is now in working condition and is a big hit with the kids. Hand Brutalist inspired nixie clock. My design goal for this one was something along the lines og “Slightly mysterious WWII bunker salvage”. This project actually made it into the Make Magazine blog (after a friend ratted me out). Don’t try this at home - ever! I was working in the man cave in the basement with a power supply design - without knowing a whole lot about power supply design. This was not only my first attempt at creating a power supply, but a high voltage one (for good measure). I applied power - and then heard a really loud bang. The entire house went dark at the same time. Concerned voices sounded from the floor above. I hadn’t just blown the circuit breaker - I had blown the main circuit breaker - rated at 50 amps. As could be expected, I had failed miserably in my attempts at power supply design. On the other hand, I also had discovered that it is possible to do vacuum metal deposition - at one atmosphere of pressure. Decatron spinner. April 18th, 2010. I tried to figure out how the original analog decatron circuitry worked, but gave up. The OG-4 runs on 450V power supply, so I guessed that I could make it spin using three IRF740 mosfets that were controlled by an ATTiny. I sketched out the necessary binary logic table for making the glow jump from pin to pin and made a short program for the AVR that basically just looped through the table controlling the mosfets. Useless, but quite satisfying to look at. Silicone adventure Niche electronics 2 February 9th, 2010. This board was intended as a generic replacement board for Pajazzo machines. The project was a really nice excercise in designing circuits and PCBs and also an excuse to get familiar with FreeRTOS and FemtoOS. In the end it turned out to be way to expensive to integrate with the intened machines, mostly because of the huge variation of connectors used in these machines and also the need for multiple interface boards. Niche electronics This piece of hardware needs some explaining. A friend bought a few of the quite rare EL-3 Pajazzo machines from - somewhere. These are quite expensive man cave furnishings, so he was quite disappointed to discover that it was impossible to install new coin mechs in them and have it operate at locations where the coins didn’t have a center hole. In normal scenarios, Arcade amusement game will trust the coin mech, when the mech sends back a “Yay, I just accepted a valid coin” signal to the machine. Not so in this case. The EL-3 has additional hard wired validation designed in. The machine itself (not the coin mech) looks for the presence of a center hole in the coins used. You cannot remove the sensors, because the game won’t start without having recevied two pulses from these. The firmware also checks for the correct timing of these pulses - according to how fast a coin will drop through the mechanism at 1G. This has to be the most paranoid coin game ever designed. I designed this little board to circumvent the issue. It snaps onto one of the IDC cables in the machine and leeches power from the same cable. Upon receving a valid coin signal from the coin mech, it will inject two pulses back into the cable, simulating the signal that the machine itself would generate if valid coins were inserted. Found some clay Pumpkinhead 2.0 Monster crab June 7th, 2009. Assembled one of robots in the excellen Gakken Mechanical Animals series today. The kids were not all that impressed. Kill all the TVs The classic TV-B-Gone is equipped with a single 4mW 940nM IR diode. I decided to make a booster - with the range of a small nuke. The light emitted is invisible with the naked eye. Great fun. Functional Went on a two day Haskell binge. Implemented the RSA algorithm. Blogged about it on the company intranet. The posting largely got ignored and the code is now lost somewhere in the abyss that is Sharepoint, protected by a company firewall. All that remains is my mandelbrot implementation (for 25 x 81 character displays…) import Complex belongs_to z c i \| magnitude z > 100 = ‘X’ \| i > 100 = ‘ ‘ \| otherwise = belongs_to (z * z + c) c (i+1) remap (x,y) = belongs_to (0:+0) ((y/25):+(x/25)) 0 wtf = map remap [(x, y) \| x <- [-40..40], y <- [-40..40]] Pumpkinhead 1.0 Interfacing Papercraft If you plan on building an army of AT-AT walkers as props for your next Star Wars themed office party, I have a recommendation for you. Don’t. This one took two people 7.5 hours to complete - using 14 sheets of A0 paper. Huge success, of course. Much like the Stonehenge prop in Spinal Tap. Retrogaming Found my old cellphone in a drawer. Unusable after they killed of the NMT band, but I really miss it. The battery easily lasted for a full week and it was built like a tank. I tried to kill it on several occasions at the time - in the hope that I would get the ok from my boss to get a newer model (It wasn’t until years later that I realized what a gem it really was). But, to no avail. It even survived immersion in a pint of beer. The classic Nokia party trick was to throw the phone onto a hard surface - watch it disintegrate - then retrieve all the pieces, reassemble the phone and watch it boot, like nothing had happened. I dare you to try the same stunt with a modern cellphone. MAME Cab I was once the proud owner of an Atari Tempest arcade machine, as well as an Atar Battlezone. Unfortunately, I had to let both of them go after having moved to a new house. I have regretted the decision to part with these classic arcade games ever since. Fortunately there is this thing called [MAME] and also this thing that is called MDF. I decided to go ahead and build a MAME cabinet, so that I once again could enjoy my favourite games. Tempest is probably the best arcade game ever designed, but it is impossible to play without the original spinner control (or a replica). Made my first PCB. Yay. Laser transparancy film, Black light bulbs, lye, some obscure peroxide variant and voila ! Tesla Coil This was my first major build - started on August 19th, 2006. I used a modest 9kV/60mA neon transformer as the power supply. This was in turn controlled by decent sized variac. The static spark gap was sourced from Information Unlimited. I had to construct a slow-start circuit to prevent the inrush current to the variac from tripping the circuit breakers in my house. The secondary coil was hand wound on a PVC form (not an excercise that I am going to repeat any time soon). The primary coil was made from several turns of copper tubing that was held in place by manually fabricated acrylic. Initially considered getting my hands on a Maxwell pulse capacitor, but decided on building a MMC bank instead. The entire assembly weighs in at 32 kilos and is 115cm tall. I have to apologize for the slightly pretentious (and unlicensed…) use of Carmina Burana as background music. Still haven’t recevied a takedown notice, so I guess it is ok :) Biofeedback I had just found a pair of homebrew biofeedback goggles in the basement - and decided to try them on. These were built sometime in the nineties. If I remember correctly they interfaced directly to the Centronics interface on my computer. I was probably reading ‘Mind/Body Integration - Essential Readings in Biofeedback’ at the time (most likely picked up at a thrift store). The only traces of this build is probably rotting away in a usenet archive - somewhere	https://timeexpander.com/gallery/	CC-MAIN-2019-51	refinedweb	2,730	72.66
Are you sure? This action might not be possible to undo. Are you sure you want to continue? Analyzing and Simulating Network Game Traffic A Major Qualifying Project Report Submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelor of Science by _______________________ Dave LaPointe _______________________ Josh Winslow Approved: _______________________ Professor Mark Claypool Date: December 19, 2001 ABSTRACT Network games are becoming increasingly popular, but have received little attention from the academic research community. The network traffic patterns of the multiplayer games Counter-strike and Starcraft were examined and documented. Analysis focused on bandwidth usage and packet size. The games were found to have small packets and typically low bandwidth usage, but traffic patterns varied widely between games. Modules for these two games reflecting these findings were added to the network simulator NS. 2 Table of Contents 1 – Introduction ................................................................................................................... 6 1.1 – Status of the Gaming World................................................................................... 7 1.2 – Trends..................................................................................................................... 9 1.3 – State of Research.................................................................................................. 11 1.4 – Synopsis of this Document................................................................................... 13 2 – Background ................................................................................................................. 14 2.1 – Examples of Network Game Development: Articles by Game Developers ........ 14 2.1.1 – “The Internet Sucks: Or, What I Learned Coding X-Wing vs. Tie Fighter” [Lin 99]...................................................................................................................... 15 2.1.2 – “1500 Archers on a 28.8: Network Programming in Age of Empires and Beyond” [BT 01]....................................................................................................... 17 2.2 – Academic Research .............................................................................................. 19 2.2.1 – “Latency Compensating Methods in Client/Server In-game Protocol Design and Optimization” [Ber 01]....................................................................................... 19 2.2.2 – “Designing Fast-Action Games for the Internet” [Ng 97] ............................ 20 2.3 – Network Simulator ............................................................................................... 21 3 – Methodology ............................................................................................................... 23 3.1 – Packet Sniffers...................................................................................................... 23 3.1.1 – Sniffer Requirements..................................................................................... 24 3.1.2 – Selecting a Packet Sniffer ............................................................................. 24 3.1.3 – Usage............................................................................................................. 26 3.1.4 – Issues ............................................................................................................. 26 3.2 – Game Selection .................................................................................................... 27 3.2.1 – Starcraft Game Environment Issues.............................................................. 28 3.2.2 – Counter-strike Game Environment Issues..................................................... 28 3.3 – Tool ...................................................................................................................... 29 3.4 – Analyzing Game Traffic....................................................................................... 30 4 – Game Traffic Analysis ................................................................................................ 32 4.1 – Starcraft Traffic Data ........................................................................................... 32 3 ............. 63 5...........................................................................2 – Server Traffic ................................................2 – Comparing Real Traffic to Simulated Traffic ..........1.........................................3 – Counter-strike Server ............................. 81 starcraft-app.......... 76 References ...... 91 cstrikeserv-app.............................h .............. 79 game-app.... 46 4..2....1............................................. 56 5 – Game Traffic Simulation............................ 58 5............................................................................................................ 88 cstrike-app...................................................................................................................................................................................................... 58 5.........................................................................................................................................................................................................cc...............4........................ 77 Appendix A – Structure of a Commview Packet Log................................................................................................................. 69 5......... 50 4....cc ..............................1 – Comparing Data Streams from Remote Players ................1................................................................... 73 7 – Future Work ...........................................2.................h ........................ 99 4 ........................................................... 75 7..... 75 7.................1 – Refinements........................3 – Comparing Starcraft Games by Number of Players..3 – Comparing Starcraft Traffic With Counter-strike Traffic.... 46 4.............................................................................................. 63 5........2.............................................................................................1 – Client Traffic ..2 – Comparing Outgoing Data Streams Across Similar Games ..........................................1 – Starcraft .........................................1........................ 90 cstrike-app.............................................................................................2 – Counter-strike Traffic Data ...1 – NS Integration ................................................................................h ..................................................................... 95 Appendix C – Useful Perl Scripts ..........h..............................................2 – Counter-strike Client ............................... 38 4......................................... 93 cstrikeserv-app....................................... 78 Appendix B – Network Simulator Code ........................................................ 87 starcraft-app................................cc...................................................... 43 4........................1 – Class Diagrams................... 75 7...............................................................2............................................................................................................................................................................................................2 – Additions .........................................cc.............................................................................. 60 5............ 71 6 – Conclusions ...........2...................................... 33 4..........................3 – Related Areas of Study........................................................................... 79 game-app........ ............................... 102 results...................pl .......................... 99 codegen...................pl ...................packet_concatenator............................................................................................................................................................................................... 105 5 ........pl.......... The delay experienced in re-transmitting packets and the overhead of packet acknowledgements can cause an enormous amount of slowdown in a game. The Transmission Control Protocol (TCP) is the most widely used protocol on the Internet. 6 . and progress is somewhat restricted compared with research on traditional TCP traffic. the amount of research devoted to network behavior such as these programs generate is deficient. These considerations are relatively new to the world of networking. with the exception of streaming media and real-time games. However. Almost all traffic that travels over the Internet. Streaming media applications and other real-time activities such as multiplayer games do not require fully reliable delivery. and only newer technologies dealing with streaming media parallel some of the issues introduced by games. and thus do not require a mechanism for retransmissions and acknowledging successful deliveries. as the underlying protocol must wait for these retransmissions and consume extra bandwidth for the acknowledgements. A game must therefore provide its own means of tolerating packet loss. and complexity. as UDP packets are not guaranteed to reach their destinations. as most Internet applications transfer text or files over TCP. the Internet was not designed with time-intensive applications taken into account. Therefore.1 – Introduction Since the release of the first multiplayer computer game. as a particularly overburdened router could lose a large amount of data before routing schemes can divert the flow of packets to compensate. depth. However. However. and games are becoming increasingly demanding on network hardware to run quickly over the Internet. the level of attention game developers have devoted to the network aspect of a game has dramatically increased as games continue to grow in quality. the size and behavior of the networks on which such games have been designed to run are also changing rapidly. Games often use the User Datagram Protocol (UDP) to avoid these problems. is carried by TCP. any of the routers through which these packets are passed can be overburdened by traffic and lose packets. but it was built on the premise that packets had to be delivered reliably and in sequential order. net.html Archives of lumthemad.net.The lack of research into networked multiplayer computer games has left a large informational gap concerning the network traffic flows that these games create. currently offline Potential mirror at. after parlor games. In these games.1 – Status of the Gaming World The lack of research into network gaming was never a problem until fairly recently. routers may be able to provide different queue management services than are used for traditional traffic. In the current environment.4 The genres of games that have the most players. this has changed drastically. High ping times correspond to high latencies between machines. checkers. 7 . with the growth of the Internet. and similar games.3 However. nearly all networked games were text based and used telnet or similar protocols to transmit data from player to server and back. On an average night. FPS have made up a large portion of networked gaming. But even with the advent of Doom. currently offline. in the last 5 years.brokentoys. especially on high loss or low bandwidth connections. the traffic generated by each of these games is quite small and infrequent. chess.000 servers for games using 1 Ping is a simple program that measures the amount of time a small (usually 64 byte) packet takes to travel to a remote machine and back.brokentoys.org/. networked gaming was still confined to a small portion of the population.org/ Archives of lumthemad. However.2 released in 1993. followed closely by Real Time Strategy (RTS) games. Better router queue management would improve the ping1 times for gamers leading to an increase in playability for many games. the player views the world through the perspective of this character (the first person part) and is usually required to move around various locations slaying monsters and other players. the vast majority of networked gamers play card games. 1. Before Doom. there are well over 10. Because of this. Since Doom. 2 3 4. are First Person Shooters (FPS) and Massively Multiplayer Online Role Playing Games (MMORPGs).idsoftware. Potential mirror at. with an amalgamation of ranged weaponry found along the way (the shooter part). Dark Age of Camelot. and while only a fifth of them login on any given day. but this has almost certainly fallen due to Asheron's Call. In addition. unlike earlier strategy games (most notably Civilization15 and various war games from SSI and others) in which the player could take as much time as he or she needed to plan his or her turn before pressing the 5 6 7 8 9 Average of 3 randomly selected nights between 10/2/01 and 12/15/01 Tribes 2.14 which was based loosely on the world from the Frank Herbert series of novels.uo.civ3.000 subscribers. and other players to interact with.000 subscribers.com First pioneered in the 70s. Dark Age of Camelot. World War Two Online.000 subscribers. Asheron's Call most likely has between 75.9 Ultima Online. several more MMORPGs have been released in recent months.12 these players consume a non-negligible amount of bandwidth. and Jumpgate all having been released since then.zone.13 adding to this total. For more information. The first RTS game was Dune 2.legendmud. 10 At one point.org/raph/gaming/book.dune2k. Anarchy Online.the Half-Life engine supporting over 40.station.com/duniverse/dune2/ See. The “big three. see. UO had advertised having over 300. and Jumpgate. this doesn't seem to match previously released subscriber figures. 11 12 13 14 15 Everquest ( Asheron's Call (. Observations and developer comments seem to indicate that about 1/5 of all subscribers play on any given night. 8 .” Asheron's Call.10 and Everquest. and battles that consist of large numbers of animated soldiers standing a few feet apart going through the same animated attack motion over and over. average 3 randomly selected nights between 10/16/01 and 12/15/01. MMORPGs have been a rapidly growing field since Ultima Online's7 release in 1996.com/asheronscall/) has an average of 12k players a night.sony.8 All MMORPGs released thus far provide some mechanism for character advancement. A MMORPG can be safely thought of as a graphical Multi-User Dungeon. Comments made by several developers on the now defunct www. World War Two Online. RTS games are generally characterized by resource collection.com for the second sequel of Civilization.net. However.11 claim to have nearly 1 million subscribers combined.5 Other FPSs support slightly smaller user populations6. Anarchy Online. unit construction.lumthemad. All of these actions happen continuously.000 and 120. large areas of landmass to travel across.000 gamers.com/)has over 410. blizzard.23 However.500 in 199719 to around $1. the developers of Quake 3.process turn button. the player communities would modify these games. Though few are as wildly popular as Counter-Strike. Total Annihilation.com/features/19990903/lincroft_06.16 each with their own variation on the theme.quake3arena. 25 www. have been around since the release of Quake. adding new multiplayer content and game styles. Age of Empires. there have been several more games released.idsoftware. This is most obvious in the development of FPS.internetnews.2 – Trends The rapid growth of the Internet and the fall in computer hardware prices started the growth of multiplayer gaming. Since Dune 2. 24x CDROM Dell Dimension 8200 Series as of 10/9/01. the recent Internet boom has placed a computer in 54% of American households with 80% of those having Internet access. Up until Quake 3. the number of RTS fans playing Starcraft17 on an average night numbers at least 20. Myth.com/isp-news/article/0.htm These modifications.00.html See. 4 GB hard disk. The mod community for Half-Life has put out over 15 mods that have been registered with the main WON servers. AWE64. id software25 released Quake 3 with minimal single player 16 Command and Conquer.com/index.gamasutra.24 Realizing this. Another factor in the increase in network gaming is the change of developer focus from single player games to multiplayer games.21 These two points taken together show a dramatic increase in potential game players. and Shogun: Total War 17 18 19 20 21 22 23 24. 4mb Video Card.html players.com 9 .22 all FPS came with an expansive single player game with multiplay usually added on as an afterthought.. many have devoted followings.com/worlds-starcraft.600 in 2001. called mods. and games styled off of action movies.18 1. Black and White. counter-terrorist games.shtml Still gathering data Custom built Pentium/200. Many of these mods radically change the game play from that of a straight deathmatch or team based capture the flag to soldier Sims. 64mb RAM.8_879441.20 Also. The cost for a computer capable of playing the latest popular games has fallen from almost $2. Currently. 000 and 50.jhtml?PRODID=187 10 .000 copies.jhtml?article=art_consolevspc. Also. and Sega have traditionally been the bastion of multiplayer games.30 While none of these games have been multiplayer. it becomes apparent that consoles are a major part of the games industry. Vampire The Masquerade - Redemption from Activision. Since then. and Pool of Radiance: Ruins of Myth Drannor from UbiSoft for examples.26 Many have emulated Quake 3 in dropping single player game play entirely (Tribes 2.27 Unreal Tournament. only 2 (Age of Empires II and Diablo 2) were games enjoyed by "traditional" gamers. games industry has also begun shifting from hardcore gaming (FPS. It is no surprise then that all of the next generation console systems from the Sega Dreamcast31 forward have included some way of connecting to the Internet to play games against others. MMORPG.com/ but console games easily outsell PC games. regardless of genre. have been released with some form of multiplayer gaming. computers are not the only source of multiplayer gaming. The top 10 Console games sell as many copies as the top 200 PC games.pdf Released in Japan in November of 1998. Examining sales figures. RTS) to more mass-market games.com/jobs/industryjobtips. the first mass-market game that is multiplayer will decidedly impact network traffic.33 Phantasy Star Online.com/releases/SOTI2001.com/games/post_gamearticle.bighugegames. and its sequels are among the best selling console games in the last year. The best selling PC game in 2000 was The Sims. Of the top 10 PC games.idsa. 27 28 29 30 31 32 33 34. Sony.28 and Majestic29).34 the first console game with a strong network based multiplayer component.com/.. a real life simulator that generally doesn't appeal to the traditionally gaming community. Clearly with the release of more and more PC 26 See Arcanum: Of Steamworks and Magicka Obscura from Sierra. many games.html and a determined focus on the network code and multiplayer level design. However. An average computer game sells between 20. Consoles systems from Nintendo.unrealtournament.com/worlds/games/pw_majstc00/hatted_jump_page.com/games/dreamcast/post_dreamcastgame.jsp. html 11 . Setting milestones correctly.gamespot. bandwidth usage.35 Unreal Tournament.000 Koreans playing one game.36 The Asia rim nations are also very involved in network gaming. Conversely.multiplayer games on to consoles (Quake 3.ravensoft.nu/archives/MUD-Dev-L/2001Q2/msg00211. most academic game studies have focused more on usability and game play issues brought about by new network protocols rather than analyzing the performance of real game protocols.37 Since few game servers are physically located in Asia or Europe.uk/pc. etc) and the release of newer networked games the numbers of players playing these games will drastically increase. Half-Life. a large volume of traffic must cross the transoceanic connections. issues related to the effects of these games on network congestion have been largely neglected in both academic and industry publications. Gaming has not been a traditional research field in academia. and setting realistic technological goals are all very important. games are looked at as more of a fun diversion rather than a business related application.co. making the scheduled ship date. despite games earning nearly as much revenue as the movie industry. with nearly 10. 35 36 37. Industry articles are more concerned with the management aspects of game development rather than the technical issues confronted by the programmers. This leads to a significant knowledge gap as to what kind of traffic patterns.com/features/bth/bth%2Dvol10%2D9. multiplayer games have been rapidly spreading to countries outside of North America.kanga. Several issues contribute to the lack of research into games. and protocols games use. alone. 1. In general.3 – State of Research Despite this massive growth and large user base.gamespot/features/aroundtheworld_pc/ Though it should be noted that Lineage has a much different subscription model:. Solder of Fortune. Finally.happypuppy. Europe has a large number of computer users has a large number of network gamers.000.html 38. but issues like developing a robust network layer or minimizing network load suffer due to the lack of economic pressure. Lineage.38 The majority of grants go to research into hardware. a popular simulator used in academic research. we measured bandwidth and packet size by player number due to the effect the number of players has on the network footprint of games. We chose two of the most popular genres of games. This module will allow researchers to gain a better idea of what a few games' network traffic impact is by simulating them. since the games industry is on a very tight development cycle. but might perform very badly under others due to one easily changed design decision. where one would expect most of the games related research to be performed. It is our goal to analyze the network traffic of two of the most popular games and develop a module based on them for the network simulator NS.nsf/anirabst2000?OpenView An after the fact analysis of what the main problems were in the development cycle. First Person Shooters and Real Time Strategies. and web related research. Because of this lack of knowledge. The games industry as a whole.39 However. reasons for good and bad performance are also not well researched. most of the published papers concerning games are postmortems40 concerning the development process. Most game developers chose their professions because they enjoy the process of making games and the end product. knowing how different types of traffic are queued at the router. it is important to look at other types of traffic and games will soon be making up a sizable percentage of network traffic. It will be possible to construct better router queue 39 40. has also shown a notable lack of interest in doing network related research. an area that changes radically every 6-8 months as each new generation of video hardware is released. Various implementations might perform well under most conditions.nsf.interact. We also wrote an extensible module to simulate these games that will provide an easy way to add further games into NS. During our analysis of these games. Fixing this sort of issue requires the knowledge that the problem exists. with the intent of representing a larger range of data than a single genre would likely provide. 12 .gov/cise/abst. In addition. and having the resources to implement a quality solution. rather than the often less applied work of academia. how they were solved.routing. most research time is spent on graphics. written by an often non-technical producer. and what new approaches saved time. Finally. 4 – Synopsis of this Document This report is divided into seven chapters that are organized as follows. Chapter 3 is the methodology. Chapter 5 is game traffic simulation. Chapter 6 contains our conclusions. Chapter 7 details the further work we would like to see done in this area. it contains a description of our work on NS and validation of our simulation. Chapter 4 is game traffic analysis. it contains the process utilized when performing our analysis of the data. Chapter 2 is the background. it contains a list of related works and commentary about them.management techniques that take into account the lack of flow control in most games. 13 . 1. as well as the size and number of packets that games produce. it contains a brief overview of the project and the motivation behind performing it. Chapter 1 is the introduction. it contains an overview of the data collected and its properties. 2 – Background Discussing the most current developments in the world of multiplayer games is useful in understanding the need for extensive research in any particular game’s behavior when running over the Internet. These developers faced issues such as minimizing user-perceived latency. This chapter discusses some of the conclusions reached by game developers working on network aspects of multiplayer games and relates them to the goal of this project. Network Simulator (NS) is a program that accurately simulates network traffic using an event-driven. mostly because this work was never accomplished.1 – Examples of Network Game Development: Articles by Game Developers The lack of research into the facets of network gaming is reflected in the low quantity of academic articles published about the subject. 14 . There are. as most pertain to more general design issues. the functionality of NS is explained in detail. it goes not currently support traffic generated by multiplayer games. so comparisons can be made between existing simulations and the sort that this project seeks to produce. and many share the same structure: a general warning to colleagues that there are a number of lessons to be learned in designing games for Internet playability. a number of articles illustrate this lack of research with a consistent shortage of references. In addition. In addition. few publications that relate to the network aspect of gaming. object oriented technique. 2. Useful mainly for studying the effects of variable packet loads on routers. coordinating the game environment between users. and compensating for Internet transmission latencies. Very few articles actually make note of previous work. the simulator is a powerful tool for analyzing network performance and illustrating traffic patterns. However. A sizeable portion of the articles that discuss network issues were written by game developers faced with the specific challenge of adapting a game to multiplayer functionality. however. bandwidth limitations. This functionality is to be implemented in our project. What I Learned Coding X-Wing vs. was that the amount of bandwidth required per user would be proportional to the number of players in a game. however. A solid majority of the information available to game developers at the time of this writing can be found here.gamasutra. This requirement set the amount of information that had to be passed between players to a large amount. The problem that arose with this.Typically. which would be difficult to achieve over slow connections.8 bps modem. but the designers’ primary goal was to provide adequate performance for users with the bandwidth of a 28. they knew that the level of complexity the original engine was capable of attaining was going to have to be supported by the new model. This would not necessarily have been very problematic. they knew that they would not be able to provide dedicated servers. The Internet has no generally available multicasting capability available to game developers. Second. Tie Fighter” [Lin 99] This article. Tie Fighter.41 describes the problems involved in designing a networking model for an existing game engine. originally published on Gamasutra.1 – “The Internet Sucks: Or. 15 . 41 Gamasutra is a website devoted to game development. First. due to the licensing issues. many articles barely describe the most critical issues behind efficient networking plan. as there are no standards in network-game interfacing as of yet. In fact. this engine had been designed for the original X-Wing game. The site is located at. Originally. so sending the same amount of data to each user required a separate transmission to every other player.1. 2. an article must relate the issues faced as unique to their designs. They could not allow gamers to set up their own servers either. because of the high expected cost of maintaining them. The designers had a number of factors to consider in re-writing their engine to effectively implement a scheme for running multiplayer games. An example of this kind of article is a post-mortem article by Peter Lincroft on issues he faced while working on X-Wing vs.com. which was strictly single-player and therefore not designed with the Internet as a consideration. This meant they had to use a peer-to-peer networking model. This increased the amount of bandwidth needed by the host. etc). A good example of this is a simple FPS with two players. Tie Fighter team realized this problem with using TCP after trying to run their game over the Internet. and packets were regularly lost in 16 . could process the data on its own and the environment would appear exactly the same for every player. The game then proceeded in a lock-step fashion. If. the game would be structured so that one player acted as a game “host. a packet is lost. which provided reliable transmissions. This means that if a packet is lost in transit. shooting. etc…) would be sent to the game host. the game would halt until that packet arrived. however. in a transmission of environment data. The majority of applications designed for networking require the reliable and orderly delivery of packets.” assembling the information collected about each player’s actions and distributing it to the other players. On LANs. it may not affect the quality of the game very much. and extends to many real-time applications. The X-Wing vs. and distributed to the other players. This is obviously undesirable. Almost all traffic on the Internet was in the form of TCP packets. The Internet. as they needed only now to send out one copy of their information. Then each machine. that this is where traditional networking concepts for the Internet are generally inapplicable to synchronizing a real-time environment between a number of distant users without a great deal of latency between cycles. with identical sets of information. as the missing data would likely only result in a slight adjustment of each user’s perception. However. They opted to have each game client send only information about its player’s actions. in which the game environment (player position. is considerably more lossy than a LAN. but greatly reduced the amount needed for other users. if the packet must be resent before any more could be processed. This model functions very poorly for real-time applications. because there was little to no need for re-transmitting packets. direction. is updated every few milleseconds. complied with those of other players. In addition. because time is as important as reliability. More likely. It is clear.It was decided that the amount of bandwidth needed could be greatly reduced with the proper information-coordinating algorithm. in which player’s commands (turning. however. the players would barely notice the change. it is retransmitted. and its receiver must simply wait for the packet to arrive. the game ran very well. These could then be assembled to determine the state of their environment. 2 – “1500 Archers on a 28. 2. Attempts at correcting this by putting a limit on the amount of time a host would wait for this information before ignoring it only made the gameplay sporadic for the affected player. It is therefore reasonable to hypothesize that any games that attempt to use TCP will experience a great deal of latency when packets are lost. Just as the X-Wing vs.8: Network Programming in Age of Empires and Beyond” [BT 01] The existing engine for this game was a single-threaded cycle of taking input and processing the game environment accordingly. i. Second. to effectively implement the algorithms necessary to run a fast. they had to begin with the most basic concepts in networking.transit. but introduced a new problem. which stopped the game while packets were re-sent. the game could still only run as fast as the slowest user. that is.e. The difference here. This led to re-transmissions. so lost packets are not retransmitted. and tended to frequently produced latencies that ranged from 5 to 10 seconds. In addition. A few conclusions can be drawn from this example. UDP is connectionless and does not guarantee reliable transmissions. Tie Fighter developers. the process by which this game was adapted for multiplayer capability is exhaustive. the developer must account for the timing issues introduced by the Internet before the design process even begins. so the cycle would take as long as the longest transmission time. real-time multiplayer games should not be run over TCP. a cycle could not be completed until the necessary information was received from every player. however. By today’s standards. is that the tolerable latency for a Real-Time 17 . This made the game run a great deal faster. An effective traffic measuring program would significantly increase the developer’s ability to see problems in a game’s multiplayer implementation long before the testing phase of the development cycle. This is the intention of our NS module. The natural solution was to use UDP in place of TCP. First and foremost. Their model required every packet delivered to function properly.1. this design team used an algorithm that involved passing only user inputs between machines and using them to run the same simulation simultaneously on all machines. well-coordinated game. This was simply unacceptable. ” and that over 500ms tended to be sluggish in terms of user-perceived latency in their game. The Age of Empires (AoE) team decided that. when communications latency is introduced. and since the user could not detect the latency. Unfortunately. the system would run smoothly under normal conditions. and everyone experiences the effects. The team reported that 250ms was barely noticeable. so transmission reliability was required. given the time required to process commands. the player in a flight simulator requires instant results. It follows intuitively that this would be the case for most RTSs. and machine speeds. A game would slow down when network traffic became heavy between users and gradually speed up as traffic returned to normal. 18 .Strategy (RTS) game is much higher than for other real-time environments. the system is slowed. with this algorithm. the game only runs as fast as the slowest machine or network connection. that 500ms was “very playable. The development team addressed this issue by maintaining a target frame rate for all users and adjusting this rate based on average ping times. This is true primarily because the amount of input from the user is a great deal less precise and tends to be less frequent. however. In addition. They achieved this by scheduling commands to be executed two cycles in the future. A person playing a flight simulator will usually be changing direction and speed almost continuously. An engine can therefore take more time to process a RTS player’s game cycle. more than suitable for its purposes. the game halts until the information is received. If there is a perceptible delay between moving a joystick and seeing the craft turn. so this algorithm is. but when a game cannot proceed without all players’ actions accounted for. previous latencies. But a RTS player will generally not notice a unit in the game take a few milliseconds to start walking to where the player clicked. Games that require more information to be passed between players. the game becomes unplayable. as the player cannot detect such small latencies. The engine had to receive all inputs to process a turn. but a person playing an RTS will generally issue commands to units in the game a maximum of only a few times per second. would likely begin to experience a greater amount of slowdown as the bandwidth requirements increase. they would implement an algorithm that allowed the game to process a cycle while receiving commands for the next cycle. though not very efficient. However. They did not make the mistake of using TCP. 19 .2. this means they were always aware of the latencies caused by network bottlenecks and slow users. 2. The article first presents a model for the typical sequence of events on the client side of the client/server architecture used in both games: Sample clock to find start time Sample user input (mouse. keyboard. the level of academic research into network gaming has been on the rise for several reasons. including growing interests in new protocols as well as concepts that can be applied in other types of programs. Essentially. NS is an excellent program for simulating the effects of network traffic. Some of the motivations and findings of this research are illustrated by these examples. however. They are putting a great deal of consideration into writing their own network libraries to avoid the effect of third party software slowing the game down. and are beginning to concentrate more on what most game developers will be finding important: good networking. and would likely benefit these and other developers. is their decision to implement extensive metering throughout the development of the project. This is a sign that research in this area will develop quickly with future releases.Ensemble Studios’ plan for their next RTS game is heavily network-oriented. Most important.1 – “Latency Compensating Methods in Client/Server In-game Protocol Design and Optimization” [Ber 01] In this article.2 – Academic Research As mentioned earlier. 2. the author goes over the basics of multiplayer game networking on the level of how an FPS controls data sent by various users and deterministic methods of compensating for latencies. They have made extensive plans involving information coordination algorithms and network game debugging utilities. but its data is based on the Half-Life and Quake engines.2 – “Designing Fast-Action Games for the Internet” [Ng 97] When considering the requirements for network usability in multiplayer games. Speeding up the communications between clients is therefore essential to keeping players interested in a multiplayer game. In the case of the Internet. This articles attempts to explain these expectations. and from his perspective. when in fact the other player had moved out of the way. The problem faced is simple to state. however. and finds client-side lag compensation methods to be critical. but feel the effects of being hit. 20 . one player experiences a result that is contrary to what he perceived. yet difficult to solve. however. the focus of the article is placed on keeping large latency differences between individual clients and the server from having a detrimental affect on gameplay. has moved out the way of the shot since it was fired. Coordinating this action with the low-ping player makes that player see an evaded shot. so it appears to the high-ping player that the shot hit. however. One player has a much greater ping time to the server than the other. The other player.2. This “slower” player fires a shot directly at the lowping player. Developers that must rely on client-side prediction and lag compensation to keep a gamer from becoming frustrated by latency are at a serious disadvantage in keeping a decent level of accuracy in the game environment.Though this model primarily seems to address an algorithm for determining frame rates. If. and this cannot always be accomplished by streamlining the network side of the game. The article does not explicitly mention this in the title. 2. there are a few expectations as far as bandwidth and latency are concerned. In either case. Take as an example a simple FPS running with two players in the game. it is important to characterize the network over which these games will be played. has not yet received data from the low-ping player indicating the dodged shot. The issue raised here is that there are a number of steps that must be taken in order to keep the user’s perceived latency to a minimum. The high-ping player. the action was coordinated in such a way that the low-ping player’s real position was taken into consideration at the server before the shot was reported. the high-ping player would believe the shot had hit. hits the other player. The first issue raised in network performance is a set of reasonable expectations regarding bandwidth. and in the case of unreliable transmissions. and run a myriad of other experiments on the simulated network. NS is particularly useful for testing new protocols in a local environment and without hardware dependencies. Simulating this tendency of routers is key to developing a good scheme for overcoming these problems. In addition. However. lost entirely. The other network performance related issue deals with latency and types of user connections. It is therefore necessary to consider the amount of data needed to coordinate the game environment between players and adjust the bandwidth limitations accordingly. once these buffers begin to overrun. The number of nodes in a star topology network directly affects the amount of data that must be sent and received by each node. They tend to use a store-and-forward scheme in which they accumulate packets in their buffers before forwarding them. It appears that most games should be designed with broadband as a basis for latencies these days. Other means of developing and testing a new. Simulating traffic over modem connections is therefore an important step in studying in-game performance. but considering modem users is also necessary to reach the entire gaming audience. unique protocol (meaning one that does not reside above another protocol) would be to physically set up 21 . this is difficult when the Internet tends to exhibit sporadic periods of congestion. Another significant contributor to latency is the packet router. This is one area where the ability to map traffic patterns on a variable network environment is exceptionally useful. Basically. It appears that modems are the worst types of connections for multiplayer gaming. packets are dropped. It provides the means by which researchers can analyze the effects of variable levels of traffic on different types of routers.3 – Network Simulator Network Simulator (NS) is a powerful tool for mapping networks in a controlled environment. determine network behavior based on empirical data. This can lead to extended periods of time in which a user in completely out of sync with game servers or other users. as modem compression schemes and bandwidth limits tend to keep latencies consistently high. leading to game halting or poor gameplay. 2. most routers are not set up to handle multiplayer game traffic very efficiently. thus increasing latency. The modules for streaming media are not yet a part of standard NS builds.and configure real or emulated models to support the protocol. 22 . Even with this case. Uses TCP. anyone can extend it to suit specific needs. and their network configuration would likely not be able to imitate the Internet. 42 43 File Transfer Protocol. the researchers are limited to the hardware resources they can obtain for the experiment. NS supports many kinds of traffic. but may be acquired from researchers directly. ranging from web traffic and FTP42 to realtime video and audio streaming.wpi. however.43 And because it is an open-source project. 2.2). called packet sniffers. We found it beneficial to write a tool for performing a variety of operations on the data (section 3. Before analyzing the data. and also found use in generating code for our modules.1. To obtain packet data. Finally.1. 6. we took the following steps in order to acquire.1. we had to find some way of taking packets from the network and reading them. 2. Fortunately. 3. tools to do this have already been developed by several different groups.3 – Methodology In our study of multiplayer games. Adapting the data taken by the sniffer to meet our statistical modeling needs became an issue. and we relate our solution for this in sections 3.4. different packet 23 .1 – Packet Sniffers In order to do any kind of meaningful analysis or simulation. Once a suitable packet sniffer was acquired and supplemented with our parsing own tools. we then set out to build modules to simulate our findings (chapter 5). we elected to use a packet sniffer. These. However. 7. In order to do this.3). 3. 5. Our results for this may be found in chapter 4. We were then prepared to conduct an analysis on the data (section 3.3 and 3.1. we needed to gather data from actual network traffic. The process of selecting a sniffer is discussed in sections 3. 4. 1. and our next step was to choose the games that would supply this data (section 3. and simulate the network traffic they generated. record all of the traffic that the network card in a computer sees.1 and 3. we ran tests designed to measure the accuracy of our simulated data (section 5. With a solid understanding of the patterns we found in our data. which is a program that captures packet data passing through a network card. analyze. we were able to collect traffic data.2). we were met with the issue of how it would be best simulated for each game. tools. This tool was useful in helping us analyze and parse our data.4). 1 – Sniffer Requirements We started by specifying a set of requirements. the main reason Analyzer (which is in an 24 . Any packet sniffer we used had to record packets to permanent storage devices so that we could perform our own statistical analysis on the data. any packet sniffer we used had to be relatively inexpensive. we would have to write a number of wrappers to transform the data into a more useful form for us. There are a large number of packet sniffers available that use Tcpdump as a back-end. though somewhat lacking.polito.1. set of features. To effectively use Windump.2 – Selecting a Packet Sniffer There are a number of sniffers available. and in accordance with our requirements. Any sniffer we used would need to generate summary measures of the data as it was collected so that we could determine which types of statistical analysis we should generate. Finally. Windump is very similar in that it only records packet data. We also wanted to be able to maintain records of various games so that we could write a simulator that took these files and generated an accurate traffic pattern from them. The packet sniffer also had to capture the time each packet was sent accurately because games tend to send many packets over a brief amount of time.1. Windump (. but virtually all of them are strictly Unix ports. There was no funding for most commercial sniffers and many had high fees.polito.it/windump/) Based on Tcpdump for Unix.it/analyzer/) Analyzer is a windows based packet sniffer with a good GUI and a decent. However. 3.sniffers have different sets of more advanced functionality. Any packet sniffer we used also had to run in Windows because a second computer dedicated to capturing packets was not readily available on the same subnet. Analyzer (. the following were considered. and it was difficult to decide on which one to choose. 3. It is a robust sniffer with the ability to log packets according to rules we set. It does not have the logging stage/observing stage 25 . to take a number of statistics. Spynet (now called Iris . and this utility would have made an exceptionally useful tool in our project. the cost of the Spynet package is approximately one thousand dollars. which causes problems in games. Without the ability to observe changes in traffic as they happen. Iris also stops recording packets entirely. The disk access also uses large amounts of system resources. it can cause serious memory usage problems when setting the packet cache to a reasonable size.. It clearly displayed the data on each individual packet and broke down the header data for each layer. However. missing those that arrive while the logging operation is happening.com/html/Products/Iris/) Since this was first written.tamos. the Spynet packet sniffer was sold to eEye Digital Security and renamed Iris. it did a poor job of sorting aggregate packets.experimental stage of development) does not suit our needs is that logging traffic locks the rest of the program so that no results can be analyzed while the sniffer is sniffing. so it was not a viable option. However. evidently replacing the unique sniffer previous known as Iris.eeye. The data the former Iris collects goes directly to memory. When logging to disk. and had a major flaw in its lack of a good logging implementation. and with a machine running a game at the same time. The amount of functionality and statistical metering options was extensive. Iris (replaced by Spynet – no official URL available) Iris was a simple packet sniffer with a reasonably well-constructed interface. Commview (. we could not adequately make our observations unless we were to develop a means of marking game events over time. and to generate reports periodically. The Spynet packet sniffer is a part of a larger suite of networking utilities that are as sophisticated as they are expensive.com/products/commview/) Commview seems to fit our requirements very well. we would add filters to Commview to ignore all traffic except from those IPs.3 – Usage After several recorded traces yielded no useful information due to configuration errors or the traces missing vital parts of each game. After completing the game. other than recording by hand. we decided to use it. Ethereal would have been an equally good choice as Commview for our project due to its exceptionally well designed interface and data export functions. we had several problems with Commview. before we mastered using filters in Commview. for most packet sniffing purposes. To minimize this. However. Ethereal (. 3. If we knew which IP addresses from which we were going to be playing the games.1. 3. but was unfortunately not considered before the project began. at what time during the trace significant game play activity took place.restrictions of Analyzer. we developed a methodology to use when recording a play session. so we did not feel the need to switch sniffers.4 – Issues Despite developing this system. we would recommend Ethereal. was having extraneous packets from other applications in our traces. and quitting the games without capturing unwanted packets from other applications. we would quit. Commview remained suitable after we found Ethereal. and then proceed to normally load the game.1. This process allowed us to capture complete traces of joining. we closed all other Internet software before loading the packet sniffer. At this point. we would begin logging. While having this information turned out to be unnecessary 26 . and does not graphically display them.com/) Ethereal is a widely ported sniffer that has all the versatility of Commview. and join it. and then stop the trace. find a multiplayer session. but does not generate statistics as well. such as further research in network gaming. One of the initial problems we had. There was no way.ethereal. playing. For these reasons. and it is one of only two sniffers ported to Windows that appear to be a finished product. picking games that would be representative of the market as a whole was a difficult process.when we came to develop our simulator. It was necessary to save the packets to disk frequently to prevent this problem. these problems were over come by using a powerful computer. There was a 10% reduction in frame rates in Counter-strike under the most computationally intensive circumstances and virtually no noticeable frame rate reduction in Starcraft. we determined that it would be best if we chose from a list of games that one or both of us had played. making it difficult to play the game. they would have many players. but there were 27 . we discovered several more criteria we needed to use in order to determine the first few games to examine in depth. However. 3. frame rates would fall. With several hundred viable titles from which to choose and not nearly sufficient time to even perform a preliminary analysis on them all. and most of the computers resources are in use (often the case when playing a game). the extra memory and processing power made a noticeable difference in some games. it will stop recording incoming or outgoing packets. If the packet buffer in Commview is set to large. it was difficult to gain an overall understanding of the traffic flows without it. though it was still an issue if the computer lacked sufficient computational power. often dramatically in slower computers. When Commview would begin logging the packets. but we felt it was important to spend most of our time analyzing a game rather than learning how to play it. when Commview logs to disk. This did not narrow the list a great deal. Even when Commview was not logging. we decided to look at games that sold well using the rational that if they sold well. The gaming systems we used were significantly above the top of the line when the games we worked with were released and had sufficient power to run the games and run the sniffer at the same time. After doing some preliminary analysis.2 – Game Selection With the myriad host of titles currently on the market. It became apparent that nearly all games layered their own protocol on top of UDP. With that decided. We also ran into a problem when logging packets. This frequent logging also caused problems playing the games. Since both Starcraft and Counter Strike were familiar. There are three races from which a user can choose. 3. and issuing commands that cause the units to move. 2 vs. 2. Players can also team up against each other and/or AI scripted “computer” players in myriad ways. and there are a variety of maps available. 3 vs. Counter- 44. while we wanted to study Asheron’s Call. best selling games in different genres. the time it took to develop our analysis process precluded studying another genre.some that used TCP. Asheron’s Call.2.2. Finally.net 28 .1 – Starcraft Game Environment Issues Starcraft is a real-time strategy game that revolves around constructing buildings and fighting units. In addition. 3. and 4 vs. Age of Empires 2 suffered from a low online user base and significantly longer games than Starcraft. We also decided to select games from several different genres. the local player played as the same race in each game. In a free-for-all. We considered several other candidates including Tribes 2. and perform other such tasks. 4 player games were recorded. 3. and all were structured so that there were two teams of equivalent size. engage enemy units. In order to control as many variables as possible in our experiment. and employed the same building strategy throughout. There are a number of ways in which players can be competitively grouped. all players vie to be the last remaining player on the map. we decided to select them.2 – Counter-strike Game Environment Issues Counter-strike is a modification to Half-Life that is distributed free over the Internet44 for owners of Half-Life or as a retail product in most game stores. were not representative of network games as a whole. and Quake 3. and we felt that comparing across genres was more important than comparing within genres. Quake 3 and Tribes 2 were both rejected because Counterstrike was a clear choice for a FPS due to its popularity. most notably Diablo 2. we decided to exclude them. Age of Empires 2. all games were played on the same map. Because the games that used TCP.counter-strike. and each has a balanced set of advantages and disadvantages over the others. Every game is played on a map. though the former ends far more rounds than the latter. they were not satisfactory when trying to visualize traffic senders and receivers.3 – Tool Once we had picked the games. 3. and recorded some game sessions. or when one team has been totally eliminated. Once each team has equipped. We almost immediately realized that although the native Commview statistical tools were reasonable for getting a rough idea of overall bandwidth. The rest of the packet. All games are played on a map. When more than 1 player joins this server a game begins. we set out to design and write a tool to allow us to generate statistical analysis on our data and aid in creating graphs. including transport and 29 . both sides are allowed to buy weapons and ammunition with the money they earned from previous rounds. The better each team did the round before. Because of these problems. The biggest stumbling block was figuring out where in the Commview header portion of the packet the time and direction information were located. or assassinate a VIP or a counter-terrorist agent trying to thwart the terrorists. each of which has its own set of objectives.strike puts the players in the role of either a terrorist attempting to hold hostages. blow up landmarks. either located on his or her own machine or one across the network. The first step in developing this tool was to decipher the file format that Commview used when outputting packets. the player must connect to a server. the more money they have to spend. we began to analyze the packet logs. they attempt to wipe out the other team with their weaponry or complete the objective. Games are divided in two ways. Each round ends either when the victory conditions are met. We also felt that we needed to see several types of graphs beyond the packets per second and bandwidth graphs that Commview generated. To play. Most involve either the Counter-terrorists (CTs) attempting to rescue a set of hostages from close to where the Terrorists (Ts) start the round or the Terrorists attempting to plant a bomb close to where the CTs start. played them several times. Each map is played several times (rounds). time runs out. This was far easier than it could have been because we were able to load the log file into Commview and look at the data in plain text rather than the hexadecimal format in which it is stored. At the start of each round. it became apparent that Java was unable to handle that amount of data. files containing bandwidth per second. but any more than that and the Java Virtual Machine would run out of available memory or crash. was saved exactly as it was when sent or received. Once we had a firm idea of how the packets were saved. and the one we chose turned out to be unable to render a larger percentage of our sample data. There are several factors that are important to determine before 30 . Changing the GUI from the Swing toolkit to the AWT (Advanced Windowing Toolkit) helped. It was initially difficult to determine the correct procedure for rendering the kinds of graphs we wanted from Excel. However. it became an almost trivial process to generate useful graphs. We decided at that point to output the packet data into a comma delimited file and import this file into Microsoft Excel for graphing purposes. and perform some statistical analysis on them. the tool was capable of outputting size and time bucket files used in our NS simulation.000 packets into memory. For an example of a Commview packet broken down into its component parts. Our first few attempts were complete successes. with some practice and modification to the output the tool generated. we had initially planned for it to perform all the graphing functionality itself. 100. we developed a Java application to parse the file. We could load somewhere on the order of 8. With these graphs we were able to determine characteristics about the traffic that each game generated. finding a good graphing package for Java was difficult. 3. but when we moved from small traces (between 1 and 5 minutes long) to longer traces. At this point we also started running into issues with graphing the packets. Throughout the project it was also used to auto-generate code for loading the buckets in our NS simulation. load the data into classes.4 – Analyzing Game Traffic In order to build an accurate simulation. However. though this was determined to have limited usefulness and excluded from the final product.network layer headers. solid knowledge of the activity being simulated is necessary. see Appendix A. and trace files containing time and size with an option to include IP addresses. When developing the tool. By the end of the project.000-packet game of Starcraft. but we were still unable to load a 20-minute. and packet throughput. First. we would graph a smaller time slice that contained that particular feature. and a few other metrics. we loaded some of the files generated by the tool into Excel and generated scatter plots. packet sizes. we took a number of steps. both average and instantaneous. As a general rule. we gathered several traces of the same type. so it was generally unnecessary to look at more than one player’s trace. Once we determined that we had enough solid data so that a graph would be reasonably representative of typical. With this data in hand. and if there was an area that appeared different. It was determined early in the process that most of the players in a given game generated similar traffic patterns. we ran it through the tool to get basic statistics that showed average bandwidth. Most important among these are bandwidth. time elapsed. 31 . we were able to determine if we needed more data or if it was safe to proceed to graphing. similar game sessions. Using this data. We generated a graph of the entire trace each time. the traffic from each IP address was contrasted with another trace from a different game session that we thought would have a similar traffic pattern. In order to determine what kind of traffic pattern each game generated. For example. for Counter-strike we took traces of games on the same server with the maximum number of players.creating a network simulation. This machine’s relevant specifications are as follows: • • • • • • Intel Pentium III 800mhz processor with 100mhz FSB 512 megabytes PC-100 SDRAM nVidia geForce2 3d graphic accelerator with 64 megabytes of DDR SDRAM UltraWide SCSI hard drive interface 10baseT network card connected to 608/108mbps DSL modem Windows 98B Operating System running Commview version 2. 4. Section 4.1 – Starcraft Traffic Data Data collected for this particular game was graphed to illustrate the ways in which games varied by number of players. but we decided that the best representation is in the form of annotated graphs. we compared the traffic generated by each of several games of the same size. First.1 relates results found in our analysis of Starcraft game traffic. we studied the relationship between traffic received by each remote player in a typical 6player session. Section 4. The purpose of collecting this data was to determine the means by which it would be possible to create a simulation for a typical game of Starcraft. and then games of varying size. These results would produce the data needed for simulating these games in NS. Throughout this process we were mainly concerned with the size of and time between each packet.2 is devoted to our analysis of Counter-strike. which we used to analyze strategies for our NS application. All Starcraft data was collected on the same machine. There are a number of ways in which the data we acquired can be structured for viewing. and how they varied across game sessions of similar size. Next. As this game has a client/server architecture.6 (build 103) packet sniffer 32 . we ran an analysis for both the typical client and servers running sessions of varying size.4 – Game Traffic Analysis Running games and recording the packet data produced a great deal of information. The same map was used for every game.1. Bottom for each. The density of each band indicates the frequency with which each packet size appears. as they never arrived. They serve to show that individual players generally produce similar traffic patterns in comparison with each other. Each graph represents 20 minutes of packets received from each remote player. The game type was Top vs. and can be found in the maps/broodwar/webmaps directory from where the game was installed.Controlled in-game variables were as follows: • • • Games were played using Starcraft: Brood War version 1. and created the game sessions. 33 .7.1 – Comparing Data Streams from Remote Players The following charts represent the traffic received by the local player from each of the 5 other players in a 6-player game. Local player logged on to Battle.net using the USEAST gateway. The map is called Big Game Hunters.. 4. with 132 bytes comprising the solid majority of points. The bands of points are separated by multiples of 4 bytes in size. Any packets lost in transmission are not represented on these graphs. There also seems to be a trend forming in the number of 122 byte packets per second increasing at about 480 seconds into the game.The distribution of points on this graph is very similar to that of player 1. the vast majority of packets are 132 bytes in length. 34 . The second-most dense band is again at 122 bytes. 35 .At this point. it appears that all players might adhere to the same general distribution of points. except that this one does not express the aforementioned trend in the 122-byte packet band. The distribution of points across each of the graphs is strong evidence that each player sends roughly the same pattern of traffic. it is difficult to derive statistical information from them alone. as they are all statistically equivalent. It was this observation that led us to conclude that there was no need to account for differences between incoming packet streams in a simulated game of Starcraft. However. Following is a graph of the relative frequency of packet sizes across the 5 remote players in this Starcraft session. since most of the plot points on our graphs overlap. 36 . at these size levels. With only relatively few packet sizes used by Starcraft. This relates to the bands of packets.The distribution is clearly around 70% 132-byte packets. 37 . with 120-122 byte packets comprising the next largest group. it is visually easy to associate those represented here with their levels on the scatter plots. a comparison of the bandwidths generated by each of the remote players solidifies the argument that they behave very similarly. Finally. on the scatter plots. this graph suggests that each player is sending the same amount of data to every other player.169872 669.4592 137.Player 1 Average bandwidth (bytes/second) Standard deviation Std dev/mean 680. as the amount of data received from each is the same when perceived by the local player.2658 0. From the graph. 4.1947 104.5378 0.0294 0.0684 0.1414 113.1897 114.201725 Player 2 Player 3 Player 4 Player 5 676. A typical game.150288 675.1.8658 0. It is for this reason we decided it would not be necessary to differentiate between remote players in our simulations. was as yet undefined. it is clear that they each contribute nearly equally to the total bandwidth used.2 – Comparing Outgoing Data Streams Across Similar Games The prototype for our NS game application was intended to simulate a typical 6player game of Starcraft using the probabilistic methodology described earlier in this document. In addition.154073 This graph illustrates the division of total bandwidth by the remote players. so it was necessary to run a 38 .169677 665. however.8436 100. just as the incoming traces showed. itself. All four graphs were cropped to 800 seconds for the sake of comparison. Of the ten sessions recorded. Every game has yielded the same pattern throughout. and it should be noted that showing only the first 800 seconds does not limit the analysis. The majority of packets are 132 bytes in size. however. There are two packets that lie out of this plot’s range. 39 . we have decided to display four as a succinct demonstration of their overall similarity.number of game sessions and compare them. They are just over 500 bytes in size and are delivered to Battle.net servers for purposes unrelated to gameplay. All traces looked like this one. 40 .The similarity between games is more evident with each graph. net server. it follows that the packet size distribution of the outgoing traffic should match that of the incoming traffic. As each player in a Starcraft session sends the same amount of data to every other player. Comparing the following graph with the previous size distribution graph illustrates that this is true. 41 . but actually represent some kind of persistent connection with a Battle.The 100-byte packets that appear to be uniformly distributed across the time axis are not sent to any of the other players in the game. and 8 players) also proved to be similar within their sizes. 42 . the 6-player comparison shown in this document is only an example of this. Games of other sizes (2. 4.It became apparent very early that acquiring a typical 6-player game’s simulation was as simple as choosing a lengthy trace as input for our simulator. Game 1 Average bandwidth (bytes/second) 3372.932 Standard deviation Std dev/mean 589.523 0.174781 Game 2 3403.082 493.6111 0.145048 Game 3 3096.799 627.2109 0.202535 Game 4 3318.153 820.4449 0.24726 The bandwidth graph in this case is almost evenly distributed between the four separate sessions. Again, the significance of this is that a typical game of Starcraft of the same size is, in reality, any game of that size. The anomalous data spike at 300 seconds has been attributed to a period of unusually high latencies in game 4 at that time (noted during gameplay), resulting in fewer packets sent. 4.1.3 – Comparing Starcraft Games by Number of Players The number of players does not have a direct affect on the average packet size, as is indicated by the following graph. Each ring represents a game, and each segment a percentage of the total packets from each trace. The graph shows that 132 is the most common packet size, with significant numbers of 118, 140, and 120-byte packets 43 appearing in the trace. This matches closely to the bands of points on Starcraft packet plots. The average time between packets is very difficult to produce with our tool due to innate problems with floating-point numbers in Java. Packet times for the Starcraft data are generally poorly represented by standard graphs, so we decided to express the next portion of our analysis using graphs of average bandwidth. 44 2 players Average bandwidth (bytes/second) 662.2995 Standard deviation Std dev/mean 106.4026 0.160656 4 players 2076.483 323.7356 0.155906 6 players 3437.764 495.3148 0.144081 8 players 4953.268 896.1799 0.180927 This graph illustrates that the amount of bandwidth used by Starcraft sessions is proportional to the number of players in the game. A 2-player game sends around 650 bytes/second. Each session depicted here is about 1400 to 1600 bytes/second from its neighbors, though the 2-player game runs at only 660 average bytes/second. Thus they do not only appear to be related, but linearly related. As the number of players increases, so does the variance in bandwidth consumed. This is likely due to the increased probability that any player in the game is experiencing a high amount of latency to another. Since the game runs in a general lock-step fashion, this directly affects the rate at which data is sent by the rest of the players in the process. 45 For example. the names of the maps played during the trace will be contained in the title of the graph. Throughout the section below.3 on Half-life version 1. the data sent by the client looks remarkably similar.0. This machine’s relevant specifications are as follows: • • • • • • • • • AMD Athlon 800mhz processor with 200mhz FSB 256 megabytes PC-100 SDRAM nVidia geForce 3d graphic accelerator with 32 megabytes of DDR SDRAM ATA-66 hard drive interface 10baseT network card connected to WPI LAN through residence hall connection Windows 98 v4. especially on the server side. this graph: 46 .4.2 – Counter-strike Traffic Data While a Starcraft game has very little deviation throughout its run. and cs_assault Games all played on LAN server located on WPI network 4.1 – Client Traffic The client-server architecture of Counterstrike creates a specific set of traffic patterns. There are very few outlying data points.2. All Counter-strike data was collected on the same machine.8 Maps used (from standard install): de_dust. regardless of how many players are in any given game. de_aztec.10. Counter-strike. and most of the packets are of nearly the same size.98 Operating System running Commview version 2. Take for example.1.6 (Build 103) packet sniffer Counter-strike version 1. has a distinct repeating pattern. over several minutes.The mean size of the packets sent by the client is around 165 bytes with a standard deviation of 40 bytes. 47 . However. tends to run quickly compared to other maps and rounds average around 2 minutes. Another key difference is that the first map. While the data are quite variable second by second. the data looks quite uniform as is shown above. it seems reasonable to conclude that the client data rate is not dependant on the number of players. even across player deaths. The play session below once again covered a map change but in this particular session. (there were between 24 and 32 active players during the time this graph shows). de_dust. the number of players varied between 7 and 11. we can still see the end of rounds by observing the large packets sent out whenever a round ends. The round cycle becomes less clear as the number of players on the server decreases. Due to the total lack of variability by player number. An interesting feature is the slight increase in average packet size at 555s due to an unknown cause that is also reflected in the bandwidth graph below. There is an interesting fall off at the end of this graph. It would appear that the client sends updates constantly. even when the player isn’t providing input.The traffic generated by one round of Counter-strike is a nearly flat line from start to finish. 48 . more than likely corresponding with the end of round/start of round sequence. 82 bytes/s It is interesting to contrast the bandwidth over time with the packets sent. it still shows distinct drop offs in bandwidth usage per second. This is more than likely the result of prolonged periods of waiting still within the game. as it seems to happen several times per round.92 bytes/s Standard deviation: 1324. 49 .Average bandwidth: 2693. While the granularity on the bandwidth graph is significantly better than the packet size graph above. This variability affects both the size of the packets sent and their frequency.2 – Server Traffic The traffic generated by the server. However. however is quite different. The assault to aztec play session has a slight increase in bandwidth usage. the same phenomenon is present in the server graph taken during the same play session. 4. it is interesting to note the differences between them. However.Average bandwidth: 3209.83 bytes/s Examining this graph and contrasting it to the assault to aztec client bandwidth graph above. which may explain the increase in bandwidth usage. There is a large amount of variability based on the number of players alive on the server at the time. During the first map in both cases the bandwidth usage looks quite similar but after the map change from dust to aztec at time 950s. but it is not as dramatic as it is in this case. the bandwidth spikes here jump dramatically in both frequency and size.2. For very large 50 . the rounds were quite short and bloody during the beginning of the aztec map in this case.42 bytes/s Standard deviation: 1958. one round goes from approximately 500s to 650s. They seem to have larger packets than normal 51 . The red ovals also correspond to firefights in which the player died.95 Largest Packet: 2886 Smallest Packet: 122 Mean Time Between Packets: 0.numbers of players (24-32) the rounds become rather obvious by the variation in packet size. featured above in the first small box.079 Total time: 1650 The game started on the map cs_assault. Rounds can be distinguished by the slow decline in the packet size sent from the server.25 Size Standard Deviation: 205. For example. Take for example the graph Assault to Aztec Server. It seems likely that the large packets of nearly 3000 bytes. The red and yellow ovals correlate with large firefights within the game. circled in green are round initialization or round termination packets. as they strongly correlate with the end of the decline of packet size. which is a hostage rescue map. Total Packets: 20815 Mean Size: 465. The player was a terrorist. The time up to the first box contains what are most likely messages sending what weapons the player’s teammate bought and their movement to their initial positions. indicated by the second large box. At this time. Another important feature is the break in the graph around 1400 seconds. 52 .firefights. the map was changed to de_aztec almost immediately after the start of a new round. After that. The graph above shows a bit more clearly the progression of a round of Counterstrike. possibly due data sent to the player containing chase mode data. each box represents one phase of the round. and moving onward until they get into another firefight. ending with the end of a firefight. followed by the players. reloading. regrouping. Each box represents one of those phases. The map change can be seen more clearly on the graph labeled Assault to Aztec Map Change. Most rounds consist of multiple battles happening at the same time in different places. is significantly delayed compared to most rounds. a map change was initiated. The map change is indicated by the blue box. It took several seconds for a round to begin after the map change. The green circle again corresponds with a round change and you can see the rapid climb of the traffic shortly afterwards. the yellow oval. It should also be noted that the peak of activity is smaller than the round before. Within 15 seconds. From 1350s to 1390s the packet size is consistently going downward. so the first firefight.The image above corresponds with a round change and then a map change shortly afterward. There was a brief firefight resulting in the player’s death. This graph also shows the general downward trend of the packet size just before a round change. 53 . Most players do not reconnect to the server in time to get into the first round. The bandwidth peaks. the number of players varied between 7 and 11. Another key difference is the first map. The large dip at 1100s is difficult to explain. trend downward for a few minutes.95 bytes/s The bandwidth usage by the server still shows the cyclical nature of Counterstrike’s network usage. 54 . However. The round cycle becomes less clear as the number of players on the server decreases. Dust tends to run quickly compared to other maps and rounds average around 2 minutes.07 bytes/s Standard deviation: 3553. with the exception of the extreme outliers that are more than likely firefights. since there was nothing in the game play to indicate any sort of dramatic prolonged bandwidth usage drop but it may be the result of network congestion. The play session below once again covered a map change but in this particular session. we can still see the end of rounds by observing the large packets sent out whenever a round ends. then the jump back upward at a round change.Average bandwidth: 5871. Note that this map change looks quite different than the one shown in the previous play session. The round packets just under 1500 bytes correlate with 7 players in the game.Total Packets: 18715 Mean Size: 309. The final feature is the map change to Aztec occurring at 950s.063 Total time: 1173.95 Size Standard Deviation: 155. The lack of the round change immediately preceding the map change makes it much easier to see the steep drop in packets sent by the server. while those just above 1500 correlate with 8 and so on.48 It should also be noted that these packets vary in size correlating exactly with the number of players in the game.65 Largest Packet: 2886 Smallest Packet: 122 Mean Time Between Packets: 0. Another notable feature is the reduced number of large firefights but an increase in their intensity. With smaller numbers of players. the teams tend to stick together and firefights usually involve all the players in the game at the time. 55 . with no two games looking the same. 4.Average bandwidth: 4950. the players are unable to move or fire but are allowed to buy equipment. After a new round. Starcraft packet sizes are close to uniform across the 56 . There is a significant degree of randomness in the Counter-strike traces.3 – Comparing Starcraft Traffic With Counter-strike Traffic The network traffic generated by Starcraft and Counter-strike look very different. One such area of difference is the model the two games use to transmit a larger than normal amount of data. This is in stark contrast to Starcraft where games are barely distinguishable.54 bytes/s The key feature on this bandwidth graph is the very clear “buy-time” intervals. The differences between the two games are significant in terms of packet size and bandwidth consumption. There are distinctly noticeable dips in bandwidth usage strongly correlating with the new round packets that would indicate that the bandwidth usage is significantly less during buy-time.51 bytes/s Standard deviation: 3695. The games are also different in the bandwidth they consume over time. increases the size of the packets when confronted with a need to send more data to the client. The Counter-strike client also follows this model.number of players. which vary over time and have a marked correlation to game events. Overall. The Counter-strike server. on the other hand. These differences are not visible when viewing a bandwidth graph but are important to note due to their effects on congestion. Starcraft's bandwidth consumption varies very little over the course of a game regardless of events occurring within the game. has a distinct cyclic pattern in its bandwidth distributions. 57 . with more packets transmitted when the bandwidth requirements increase. though the packet sizes are more variable than those in Starcraft. the amount of bandwidth consumed by a Starcraft player is comparable to bandwidth consumed by a Counter-strike client. Counter-strike. A 6-player game of Starcraft has the local player sending between 3000 and 3500 bytes/second. and a Counter-strike client connected to a mostly-full server typically sends a little over 3200 bytes/second. however. we began to develop algorithms for generating simulated traces that would mimic traces generated by actual games. and repeats. the number of packets for each size). We experienced some difficulty in dealing with the coarse time granularity introduced by the nature of operating systems (50ms in Windows 98) and by Commview. sample trace generator that could be built into NS with few problems. We created an application. we realized that the traffic patterns generated by games of Starcraft generally consisted of packets of distinct sizes delivered at relatively short intervals. it is possible to probabilistically generate any trace. waits for a time chosen from the time bucket. The other bucket contained the time between packets and the number of packets associated with each time interval. called game-app. There were a large number of 0-value time deltas in 58 . we hypothesized that a typical Starcraft session could be simulated by selecting weighted values for packet size and time since the last packet was sent. The functions that generate any given packet’s size and time delta use an algorithm that uses a random number generator in tandem with our probabilistically weighted buckets. for a single source IP. and that by fine-tuning this process we could develop a generic.1 – NS Integration In analyzing our data.5 – Game Traffic Simulation With the analysis completed. 5. but it became obvious that a relatively simple solution could generate a generally accurate simulation. that upon invocation reads bucket files generated by our tool (see section 3. From these observations. and each size’s corresponding frequency of appearance in the trace (essentially. Using this system. Building our probabilistic simulator into this structure was relatively simple. and repeating the process. The first contained the sizes of every packet in a given trace. and running a simulation based on these probabilistically selected numbers. The basis of our algorithm was that the NS timing for an application involves sending a packet of a specified size. We used our tool to generate. picks a packet size from the size bucket. but always steadily.3). waiting for a specified interval. although it currently only supports the UDP protocol. sends it. We developed several algorithms. two probability buckets. The data is remarkably uniform over time with respect to size. and can be adjusted to suit any application that experiences similar effects. NS users can select the number of players by adjusting a variable (gameSize_). yet effective fix to this problem was to limit the number of packets that could be delivered in a single burst. The server application. The data sent by the client in Counter-strike does not vary based on the number of players in the game or the status (alive or dead) of the player. With these factors in mind. At the end of each round. each ending with a firefight and a drop in the overall packet size. Each segment of a round has its own effective maximum and minimum packet size. however. These bursts in traffic tended to create inaccuracies in our simulations. as well as a burstiness and outlier percentage. A simple. we developed a model with several variables. and these were built into the Starcraft NS application. Typical traces were generated for 2. The Counter-strike application currently comes in two parts. but varies slightly in the number of packets sent per second. the default value is 6 players. Further research into Starcraft’s behavior with differing numbers of players resulted in a specialized application for the game. The number of outliers seemed to correlate more strongly with the number of players in the game and 59 . Our analysis showed that within each round there were several segments. so the cstrike-app class was derived from game-app and only overrides its parent class to load the buckets. This data pattern was a good match for the use of the bucket algorithm developed for game-app. 6. and 8 player games. Due to the cyclical nature of the packet size the server sends and the bursts of packets that are sent during firefights. a client application and a server application.our initial time buckets that indicated a number of packets were sent in such rapid succession such that Commview or the operating system could not detect the time between packets. This modification kept unusual bursts from distorting the simulation. we decided that the probabilistic model would not work well. each able to be tuned based on the number of players in the game and the average round length. the packet size drops as well as the number of packets per burst and the frequency of bursts. 4. which is derived from the probabilistic application. is quite different. the packet sizes would climb again and the process would repeat itself. as they sometimes range higher than the node queues can handle. As the round goes on. due to time constrains. This provides a high level of customizing ability and will allow games to be compared to others within and outside of their genres. but found that this would limit the games to a specific traffic pattern that does not necessarily define every game of its type. the transition between segments and the packet timer were not able to be fully implemented.1 – Class Diagrams The aim of the class hierarchy implemented in our simulators is to create at least one unique class for every game simulated. A rudimentary version of this is included in our ns sample.1. 5. however. We had considered grouping games by type. 60 .the map being played. it will fill the bucket lists with the appropriate pre-recorded data start() – start sending Starcraft packets stop() – stop sending Starcraft packets command() – tcl command interpreter CstrikeApp : GameApp No variables init() – calls fillTimeBuckets() and fillSizeBuckets(). overrides GameApp init’s call to readBucketFiles() fillBuckets – depending on value of gameSize_.Denotes inheritance . such as packet size or delta time packets : number – number of packets associated with the value GameApp bucket : type – stores a value and it’s frequency of occurrence in a trace sizes : list of buckets – holds a list of sizes and their associated frequencies times : list of buckets – holds a list of times and their associated frequencies totalSizePackets : number – used for indexing totalTimePackets : number – used for indexing start() – start sending game packets stop() – stop sending game packets command() – interprets tcl script commands init() – a simple initialization function that supplements constructor selectBucket() – returns a value from a bucket selected probabilistically from a specified bucket vector readBucketFiles() – reads list of buckets from file next_snd_time() – computes the time between a packet just sent and the next in queue StarcraftApp : GameApp gameSize_ : number – can be set in tcl script to determine number of players in simulated game init() – calls fillBuckets().bucket value : number – a value. overrides GameApp init’s call to readBucketFiles() fillTimeBuckets() – enters typical CounterStrike client trace time deltas into time bucket list fillSizeBuckets() – enters typical CounterStrike client packet size values into size bucket list start() – start sending Counterstrike client packets stop() – stop sending Counterstrike client packets command() – tcl command interpreter 61 . timeInterval burstPct : number – ranges from 0-100 and indicates the percentage of all transmission times that send a burst of packets (more than the normal amount) burstCoef : number – a multiplier for the normal number of packets in a burst minEffSize : number – minimum standard size of packets in this interval. 62 . and is therefore derived from GameApp. maxEffSize : number – maximum standard size of packets in this interval. Anything smaller than this is considered an outlier. and all inherited functions from class App are listed in GameApp’s diagram. selectBucket() and readBucketFiles() are the only functions not derived from App. and also serves as a template for game classes that can use this form of simulation. and its “bucket filler” functions read from a set of previously generated buckets that each correspond to a particular game size. GameApp is derived from this class. Since Starcraft sessions can specify a number of players. StarcraftApp is a game that utilizes the probabilistic algorithm. outlierPct : number – percentage of all packets whose sizes are anomalous outlierCoef : number – the size difference between an outlier and minEffSize or maxEffSize CstrikeServApp timeInterval : type – contains values for packet size and frequency. GameApp provides the probabilistic functionality described earlier. tiaTimeIntervals : list of timeIntervals – timeIntervals are used to differentiate between network activity cycles produced by the game curInterval : number – the current interval roundTime : number – the amount of time devoted to this timeInterval init() – overrides App init functions start() – start sending Counterstrike server packets stop() – stop sending Counterstrike server packets command() – tcl command interpreter NS has a virtual base class called App from which all application-level simulation modules are derived. Anything smaller than this is considered an outlier. its class differs from GameApp in that it has a variable (gameSize_) for this. there are sets of values that determine its packet distribution. Within each cycle.2 – Comparing Real Traffic to Simulated Traffic In order to determine whether our NS implementation could portray an accurate representation of the data collected. which is also derived from GameApp. 5. See section 4. but its algorithm is as follows: Every distinct cycle of traffic patterns is rotated in a round-robin manner.The Counter-strike client is represented by the CStrikeApp class. The following graphs are scatter-plots of the data collected from a session of Starcraft and its corresponding simulation in NS. As the data from any given client is generally uniform between game sessions. a typical trace was used to fill the buckets for this game. we ran several simulations and compared them with actual trace data.2 – Counter-strike Traffic Data for details on how the cycles differ from each other. This class was not fully implemented due to time limitations. however. but with an increased standard deviation in the bandwidth. These values are explained in the class diagram. 5. The Counter-strike server.2. applies a cyclic pattern to the data it sends.1 – Starcraft Starcraft results turned out to be close to the actual trace data in terms of average bandwidth. 63 . 64 . The following graphs illustrate this: Average bandwidth: 3437. only 100-200 bytes. and a more uniform distribution of packets larger than 152 bytes.144 65 .These graphs show that the simulated data produces more evenly distributed bands of 118 and 120 packets especially.764 Standard deviation: 495. greatly accentuates differences in traffic. The simulated data looks much more dense than the real data. Bandwidth graphs can more clearly distinguish the difference between the actual and simulated data.3148 Std dev/mean: 0. but they each send about the same amount of traffic. The scale of these graphs. for instance. 92 bytes/second Standard deviation: 1373.403 Std dev/mean: 0. These 0 values create a level of burstiness unlike real traces. and this session can therefore represent the rest. As the amount of data sent in every burst is better curbed. It seems the next important step in honing this algorithm is to find a way of achieving this. The simulation for this typical 6 player game shows a 36% increase in standard deviation over the real trace. 66 . We found that these results are typical of every 6-player game we had recorded.Average bandwidth: 3493. as well. even though the average bandwidth for each is less than 60 bytes/second from the other.393 The variance of the simulated data is very large in comparison with that of the actual data. We were interested at this point in determining whether these results would be similar between games of varying size. and it would likely be beneficial to find a way around this problem in future work. We believe this is due to the large number of 0 time deltas in the buckets used for this simulation. the simulated data should move toward a real trace’s packet transmission time variance. 1799 0.268 896.4026 0.764 495.2 players Average bandwidth (bytes/second) 662.180927 67 .160656 4 players 2076.7356 0.144081 8 players 4953.483 323.3148 0.2995 Standard deviation Std dev/mean 106.155906 6 players 3437. 138 0. 68 . 6. but the simulated data behaves slightly differently.258 1341.2 players Average bandwidth Standard deviation Std dev/mean 559. The amount of variance takes an immediate climb to a constant level between the 4.615 1699. This shows that the simulations tend to become very inaccurate in terms of bandwidth distribution once the highest and lowest bandwidths in the real data become large enough to allow these levels of variance to occur.715 0.9632 110.1.7073 0.6543 0.357037 The amount of variance in the data was shown to increase with the number of players in section 4.19761 4 players 2042. but remains very close to the actual values in the 2-player game.107 753. and 8-player games.369083 6 players 3486.384693 8 players 4760.3. 2. Obviously.52 bytes 235. and we did not perform verification testing early enough in the process to discover this error. These problems were found to be caused by some limitations of the JVM and a poor selection of a trace file for the template of this simulation.93 bytes The Counter-strike client application was our first hard-coded NS app.5. It suffers from a number of flaws because the process for creating applications had not yet been fully developed at the time we made it.72 bytes 147.13 bytes 65. the simulated data is a poor fit by packet size. 69 . Our methodology for developing the application was flawed initially.2 – Counter-strike Client Actual Data Average Packet Size: Actual Data Standard Deviation: Simulated Data Average Packet Size: Simulated Data Standard Deviation: 170. The variance on the packets is far too large and the average size is almost 40% larger than it should be. 58 1450. the bandwidth usage is also significantly incorrect. This would indicate a significant error in the time component of the simulation.60 Due to the problems with packet size.05 1606. 70 . A rebuild of the simulation seed data would make it fit much closer to the actual data. However. the errors above should lead to a 30-40% increase in the bandwidth used rather than the 20% that is demonstrated here.12 3590. The Counter-strike client app is not totally beyond usefulness.Actual Data Average Bandwidth: Actual Data Standard Deviation: Simulated Data Average Bandwidth: Simulated Data Standard Deviation: 2954. the server application could work well. With some tweaking to the initial conditions and some work on the timing aspect.25 bytes 256. and turned out to be well off from the average size.06 bytes The server was not yet completed at the end of our project.3 – Counter-strike Server Actual Data Average Packet Size: Actual Data Standard Deviation: Simulated Data Average Packet Size: Simulated Data Standard Deviation: 528.61 bytes 402.5. 71 . The default times between intervals also proved to be significantly off as is shown above.2.77 bytes 102. The initial timeInterval data values were a guess. Several problems with the seed variables of the model are apparent looking at the data above. but we are including it for the sake of completeness. Once the packet size problem is corrected. generate a trace using that data. these games can still be simulated accurately. This allows a user to take the analysis presented above. We have also included several trace files with our MQP to facilitate this usage.Actual Data Average Bandwidth: Actual Data Standard Deviation: Simulated Data Average Bandwidth: Simulated Data Standard Deviation: 5988.08 3285. Despite the inaccuracies of the simulations. the server would provide an accurate simulation of bandwidth consumption. despite the large difference in average bandwidth. Note that the simulated standard deviation is quite close the actual standard deviation. and get a more accurate simulation.25 9705.13 This is shown quite well with the above graph.17 3166. NS has a built-in trace mode that takes a file with sizes and times and sends them out in the order specified in the file. 72 . The simulation does a good job of accurately simulating the size of the bandwidth bursts the server creates as well as the lulls in data transmission. Most importantly. we believe the need for simulating these games will grow as well. and to provide a means of facilitating future research. We intended to fill some of this knowledge gap with a study on how games behave over the Internet. It seems the key to understanding the traffic patterns of a game is to analyze enough data to be able to distinguish any factors that may affect the way they behave. and the structure of our code is amicable to extension. the modules for these games require some amount of modification before they can be considered accurate representations of real traces. as well as those that vary in aspects such as size. Our methodology proved true to our initial goals. As the level of attention devoted to the network aspect of games increases. as these games are simulated in NS. Our main tasks in this undertaking were to provide some meaningful analysis of network traffic generated by multiplayer games. they must be compared and contrasted before any simulation attempts can be trusted for accuracy. there is still some amount of progress to be made on the latter. In studying the behavior of multiplayer games over the Internet. even as the popularity of network games continues to grow. than on building it. As there are a number of factors that can vary the behavior of any given game between sessions. There are a number of lessons that were learned in implementing our goals. it is very important to build simulations early and analyze them thoroughly so as to leave time for tweaking it to meet specifications. Controlling as many factors as possible yields positive results. More time is spent on configuring a game simulator. As games and other real73 . we were able to construct simulations of two games with the intent that they would be solid representations of the games’ traffic patterns. While we were successful in meeting the former objective.6 – Conclusions The amount of research devoted to network games is lacking. In addition. and to simulate this traffic using a network simulator. so it is important to compare game sessions played under similar conditions. in our experience. playing style. one must first perform rigorous analysis on the data to be simulated. However. or network locality of players. it seems to be irrefutable that in order to simulate the traffic a game generates. that is. this may not always be necessary. Simulation benefits this kind of research. the development of protocols that better serve the behavior of games is likely to become a strategy for developers faced with increasingly network-intensive games. but in the future. NS is already in use by research groups working on a variety of experimental protocols and routing schemes. 74 . as well. It is possible that the Internet will begin to conform to games. they have had to adapt to the IP protocol. Most use a custom-built protocol on top of UDP in order to find a balance between advantages and disadvantages of TCP and UDP.time applications were not largely considered in the design of the Internet. However. With most games. However. While they were completed to some degree. and with a little work. there was a rather large set of topics that while interesting and useful. we did not have time to do rigorous testing with various bucket distributions. Some further work in this area should be performed before serious usage beyond the scope of our tests using game-app is done. so the addition of those items would be welcome. Our first attempt at game-app gave simulations within 10% of expected mean. Also. most likely due to some problems with timing. this could become fully functional. 7. developing an NS application for 75 .7 – Future Work Despite the number of tasks we accomplished. We also planned to add more features than we had time for. and with further refinements we were able to make it perform within 5% of expected mean. Second. we lacked the time or resources to pursue. 7. we wanted to work a bit more on them so they would be as polished as the rest of the project. For example. By the end of the project. Our early analysis on packet size distribution and burst size was promising.2 – Additions There were several areas that while within the scope of the project. were outside the scope of our particular project. we had refined the analysis process of a game down to a few hours for some basic metrics and a few days for details. Finally. First. the functionality to determine when to send the next group of packets has not yet been fully implemented and little testing has been performed.1 – Refinements There were two tasks we were still attempting to complete as our project ended. we could only perform limited analysis on game-app and its related classes in NS. working on more games would take a small amount of time while at the same time being very worthwhile. game-app creates simulated traffic with bandwidth variance that is much higher than in the real traces. there are always a number of opportunities for improvement. we were able to design a basic structure for a Counter-strike server simulator and partially implement it. Choices were made throughout the project that required discarding options. them would be limited to bucket generation and testing. we had two main choices for topics. writing an NS app that handles TCP games would be a valuable addition to our work. this area still needs research and with some of our tools. While the marketplace has overwhelmingly chosen UDP for its games. 7. to generate this data. TCP might turn out to have promise if some modifications are made that reduce the severe problems a drop packet creates for games. However. and packet loss. it only accepts the output files of one packet sniffer. A detailed traffic analysis of one or two games identifying what each packet does and the exact effects of packet loss and out of order packets could enable even better NS simulations to be written as well as demonstrating how such network events affect games. it would be possible to compare and contrast several games within several genres with each other within a week’s time and generate definitive simulations by genre rather than by game. Another promising path uses our NS additions to determine how a large number of game players on a network would affect congestion. router queuing.3 – Related Areas of Study When we first started this project. We made the decision early on to focus exclusively on UDP games due to the dramatic differences between TCP and UDP games. Commview. or do a brief overview of the games and write a NS addition to simulate them. We could either do in depth analysis on games as a whole. Similarly. this process could become much easier for future groups. 76 . while the tool we wrote can produce a great deal of different useful types of output. Finally. A detailed review in this area could change the way the games operate over networks and improve performance for game players and non-game players alike. Adding modules for other popular sniffers would greatly increase the potential user base for the tool. With this refined process. Writing and simulating TCP games is another interesting area of study. Research into this area might prove very valuable for both industry and academia. References [Arm 01] Armitage. Mark.8: Network Programming in Age of Empires and Beyond.net/garmitage/things/quake3-latency-051701. An interesting tale of specific problems encountered in attempting to adapt a seemingly latency-intolerant game to multiplayer capabilities. Paul and Terrano. and a good resource for developing multiplayer games. “The Internet Sucks: Or. March 2001.” Gamasutra. [Lin 99] Lincroft. Yahn W. reducing perceived latency using a variety of methods.gamasutra. areas of concentration. Peter. and conserving bandwidth.htm. “1500 Archers on a 28. Yu-Shen. This was a successful endeavor.”. “The Right Decision at the Right Time: Selecting the Right Features for a New Game Project.” Gamasutra. What I Learned Coding X-Wing vs.” Gamasutra.com/features/20010926/luban_01.. and details behind typical network gaming models. Very good resource for academic study. [Ng 97] Ng.home.gamasutra. [Ber 01] Bernier. “Lag Over 150 Milliseconds is Unacceptable. Extensive exploration of user-perceived latency tolerance. Very well written paper that describes the advantages.htm. including their motivations. disadvantages.” Gamasutra. [BT 01] Bettner. Luban.htm.doc. A portrayal of some issues involved in creating a multiplayer system using an already constructed game engine. [Pas 01] Pascal.gamasutra. Discusses the separate agendas of a typical game design team.. February 2001. Conclusions were drawn based on noticed user responses to increasing levels of perceived latency and how latency factored into game selection.com/features/19970905/ng_01. “Designing Fast-Action Games for the Internet. attempts to cover network issues across all genres. “Latency Compensating Methods in Client/Server In-game Protocol Design and Optimization.. September 2001.htm. Tie Fighter.gamasutra. end-product goals.html. 77 . Grenville. May 2001.” Game Developers Conference. Discusses client-side prediction and lag compensation as viable means of improving gameplay. and priorities. Short treatise on user tolerance for game latency in id Software’s Quake III.. September 1999.com/archives/proceedings/2001/bernier. September 1997. This is an example of one packet. 1 in.Appendix A – Structure of a Commview Packet Log Each line represents one packet. Original packet: #2002F000C01EA00397600045A4187C3005004261D9F0800450000414887000080112 29782D7E4F782D7E4E76987697D002D04567E140000E52E008017957879E8BE1F7A F91348B66C42391E221851432E10982C2C400F9D00# Start delimiter: # Direction(0 pass. 2 out): 2 Padding: 00 Minute: 2F Padding: 00 Hour: 0C Millisecond: 01EA Padding: 00 Second: 39 Unknown: 76 Ethernet: Destination MAC address: 00045A4187C3 Sender MAC address: 005004261D9F Other ethernet stuff: 0800 IP: 4500 Datagram Size: 0041 Identification (packet number?): 4887 Flags?: 0000 TTL: 80 Protocol:11 Header Checksum: 2297 Sender IP address: 82D7E4F7 Destination IP address: 82D7E4E7 UDP: Source Port: 6987 Destination Port: 697D Length (header?): 002D Checksum: 0456 Payload: 7E140000E52E008017957879E8BE1F7AF91348B66C42391E221851432E10982C2C40 0F9D00 End delimiter: # 78 . class GameApp.h" #include "packet.h" #include "app. }. double dTimeDelta. int packets. }.Appendix B – Network Simulator Code game-app. }. struct bucket { double value.h" #include <iostream> #include <fstream> #include <vector> #include <stdlib. // Sender uses this timer to // schedule next app data packet transmission time class SendTimer : public TimerHandler { public: SendTimer(GameApp* t) : TimerHandler().bkt" #define MAX_CONSEC_PKT 3 struct pkt_data { int iSize.h> #define SIZE_FILE "size. 79 .h #ifndef __GAME_APP__ #define __GAME_APP__ #include "timer-handler. protected: GameApp* t_.bkt" #define TIME_FILE "time. t_(t) {} inline virtual void expire(Event). // called by SendTimer:expire (Sender) void send_ack_pkt(). int totalSent_. // Start sending data packets (Sender) void stop(). int readBucketFiles(char sizeFileName. double elapsedTime_. // called by AckTimer:expire (Receiver) protected: int command(int argc. vector<bucket> sizes. bucket selectBucket(int numPackets. char* timeFileName). void start().vector<bucket> bucketList). // Stop sending data packets (Sender) int totalSizePackets. vector<pkt_data> trace. 80 .// Game Application Class Definition class GameApp : public Application { public: GameApp(). void send_game_pkt(). int totalTimePackets. vector<bucket> times. const charconst argv). t_->send_game_pkt().h" #include "game-app.cc // Written: 11/13/01 // #include "random.numPackets)+. } // Constructor (also initialize instances of timers) GameApp::GameApp() : running_(0). } bucket GameApp::selectBucket(int numPackets. index = 0.h" #include "sys/time.5). // help with truncating 81 . call send_game_pkt() void SendTimer::expire(Event) { // cout<<"Expired timer"<<endl.game-app. snd_timer_(this) { totalSizePackets = 0. // When the send timer expires.vector<bucket> bucketList) { int ran. ran = (int)(Random::uniform(0. } } class_app_game. index.h" // GameApp OTcl linkage class static class GameAppClass : public TclClass { public: GameAppClass() : TclClass("Application/Game") {} TclObject create(int. const charconst) { return (new GameApp). totalTimePackets = 0.cc // // Authors: Josh Winslow and Dave Lapointe // File: game-app. . space. and a double time until the next packet // should be sent.// run through the buckets subracting the number of // "hits" in that bucket from the randomly selected // number until the generated number hits 0 or less while(ran>0) { ran -= bucketList[index]. return bucketList[0]. double time=0. trace file NOT read" << endl. } while(traceFile >> size >> delimiter >> time) { if(traceFile. 0. return -1.0 // or // 1452\| 0.E. // so cin works properly ifstream traceFile(szFilename). temp = new pkt_data.3432432 int GameApp::readTraceFile(char szFilename) { int totalPacketsCheck=0. 82 .eof()) break. }//end selectBucket // Return the bucket value // from the bucket we // selected above // trace files are of the format an integer for the size. // check that the file handle is valid if(traceFile == NULL ) { cout << "Invalid file handle. char delimiter. if(index>0) return bucketList[index]. index++. // 132. pkt_data temp.packets. int size=0. // I. a single // character delimiter. } index--.. totalSizePackets += numPackets. } while(sizesFile >> size >> delimiter >> numPackets) { if(sizesFile. temp->dTimeDelta = time. // single character delimiter. temp = new bucket. double time=0.3300000000000409. double size=0. int totalPacketsCheck=0. 19 int GameApp::readBucketFiles(char* sizeFileName.push_back(temp). // 132. // check that the file handles are valid if((sizesFile == NULL) \|\| (timesFile == NULL)) { cout << "Invalid file handles. } // bucket files are of the format: double the value of the bucket...temp->iSize = size. char timeFileName) { int numPackets=0. space. temp->value = size. bucket* temp.E. sizes. char delimiter. I. trace. // so cin works properly ifstream sizesFile(sizeFileName). } return 0. temp->packets = numPackets. int i=0. and an integer for the number of // times that value appeared. } 83 . ifstream timesFile(timeFileName). i++. bucket files NOT read" << endl. 36614 // or // 0. exit(-1).eof()) break.push_back(temp). temp->value = time.push_back(temp). NULL). while(timesFile >> time >> delimiter >> numPackets) { if(timesFile. argv)). 84 . } void GameApp::init() { // seed rng timeval temp. times.i=0. } return 0.resultf("no such agent %s".eof()) break. totalTimePackets += numPackets. gettimeofday(&temp. argv[2]). const charconst argv) { Tcl& tcl = Tcl::instance(). temp = new bucket. if (argc == 3) { if (strcmp(argv[1]. } return (Application::command(argc. } // OTcl command interpreter int GameApp::command(int argc. i++. return(TCL_ERROR). temp->packets = numPackets. if (agent_ == 0) { tcl. } } //add filename loading here. "attach-agent") == 0) { agent_ = (Agent) TclObject::lookup(argv[2]). value. 85 . send_game_pkt(). } void GameApp::stop() { running_ = 0. snd_timer_.resched(next_time_). totalSent_ += (int)size.tv_sec).times). double next_time_. do { size = selectBucket(totalSizePackets. }//end if } // Schedule next data packet transmission time double GameApp::next_snd_time() { bucket time = selectBucket(totalTimePackets. running_ = 1. agent_->sendmsg(size. totalSent_ = 0. bucket size. elapsedTime_ = 0.TIME_FILE). } while(((next_time_= next_snd_time()) == 0) && (count <= MAX_CONSEC_PKT)).sizes). count++. } // Send application data packet void GameApp::send_game_pkt() { if (running_) { int count = 0. readBucketFiles(SIZE_FILE. } void GameApp::start() { init().value).Random::seed(temp. elapsedTime_ += time. return(time. } // Receive message from underlying agent // We don't do anything with it.value.value). but it is necessary to declare one void GameApp::recv_msg(int nbytes. const char msg = 0) { } 86 . const charconst argv).h" class StarcraftApp.starcraft-app. void stop(). // Starcraft Application Class Definition class StarcraftApp : public GameApp { public: StarcraftApp(). void fillBuckets(). int gameSize_. void start(). #endif 87 . protected: int command(int argc. void init().h #ifndef __STARCRAFT_APP__ #define __STARCRAFT_APP__ #include "game-app. // corresponds to number of players in game }. } 88 . // Constructor (also initialize instances of timers) StarcraftApp::StarcraftApp():GameApp() { bind("gameSize_".resultf("no such agent %s". "attach-agent") == 0) { agent_ = (Agent) TclObject::lookup(argv[2]). } } class_app_starcraft. argv[2]). if (agent_ == 0) { tcl. } // OTcl command interpreter int StarcraftApp::command(int argc.h" // StarcraftApp OTcl linkage class static class StarcraftAppClass : public TclClass { public: StarcraftAppClass() : TclClass("Application/Game/Starcraft") {} TclObject create(int. ADD NUMBER OF PLAYERS OPTION #include "starcraft-app. &gameSize_).h" #include "random.cc // Written: 12/02/2001 // THINGS TO DO: // 1. const charconst argv) { Tcl& tcl = Tcl::instance().cc // Author: Dave LaPointe // File: starcraft-app. } } } return (Application::command(argc.h" #include "sys/time. const charconst) { return (new StarcraftApp). argv)). return(TCL_ERROR). if (argc == 3) { if (strcmp(argv[1].starcraft-app. send_game_pkt(). totalSent_ = 0. } void StarcraftApp::fillBuckets() { This function contains four very long lists of time deltas and packet sizes. fillBuckets(). elapsedTime_ = 0. NULL). Random::seed(temp. and has been cropped to save space.tv_sec). gettimeofday(&temp. } 89 . } void StarcraftApp::stop() { running_ = 0. running_ = 1. } void StarcraftApp::init() { // seed rng timeval temp.void StarcraftApp::start() { init(). void init().cstrike-app.h #ifndef __CSTRIKE_APP__ #define __CSTRIKE_APP__ #include "game-app. #endif 90 . void stop(). void fillTimeBuckets(). void fillSizeBuckets(). protected: int command(int argc. }. const charconst argv).h" class CStrikeApp. void start(). // Game Application Class Definition class CStrikeApp : public GameApp { public: CStrikeApp(). h" #include "sys/time. argv)). } void CStrikeApp::start() { init().h" // CStrikeApp OTcl linkage class static class CStrikeAppClass : public TclClass { public: CStrikeAppClass() : TclClass("Application/Game/CStrike") {} TclObject* create(int. } //call superclass? return (Application::command(argc. } } //add filename loading here.cstrike-app. return(TCL_ERROR).resultf("no such agent %s". if (argc == 3) { if (strcmp(argv[1]. const charconst) { return (new CStrikeApp). } } class_app_cstrike. if (agent_ == 0) { tcl.cc // Written: 11/28/01 // #include "cstrike-app. // Constructor (also initialize instances of timers) CStrikeApp::CStrikeApp():GameApp() { } // OTcl command interpreter int CStrikeApp::command(int argc.h" #include "random.cc // Author: Josh Winslow // File: cstrike-app. argv[2]). 91 . const charconst argv) { Tcl& tcl = Tcl::instance(). "attach-agent") == 0) { agent_ = (Agent) TclObject::lookup(argv[2]). } 92 . } void CStrikeApp::init() { // seed rng timeval temp. fillTimeBuckets(). gettimeofday(&temp. and has been cropped to save space. } void CStrikeApp::fillTimeBuckets() { This function also contains a very large amount of packet information. Random::seed(temp. fillSizeBuckets(). elapsedTime_ = 0. totalSent_ = 0. send_game_pkt(). NULL). } void CStrikeApp::stop() { running_ = 0.tv_sec).running_ = 1. double outlierPct.h" #include <iostream> #define TOTAL_INTERVALS 5 class CStrikeServApp. protected: int curInterval. int running_. timeInterval tiaTimeIntervals.h #ifndef __CSTRIKESERV_APP__ #define __CSTRIKESERV_APP__ #include "random. t_(t) {} inline virtual void expire(Event). protected: CStrikeServApp t_. const charconst argv). }. int gameState_.h" #include "timer-handler. struct timeInterval { double burstPct.h" #include "packet. double burstCoef. class CSSSendTimer : public TimerHandler { public: CSSSendTimer(CStrikeServApp* t) : TimerHandler(). void start(). // CStrikeServApp Application Class Definition class CStrikeServApp : public Application { public: CStrikeServApp(). int minEffSize. int maxEffSize. double outlierCoef. void init().cstrikeserv-app. }. // If 1 application is running 93 .h" #include "app. int command(int argc. void stop(). void send_css_pkt(). double roundTime; CSSSendTimer css_snd_timer_; // SendTimer }; #endif 94 cstrikeserv-app.cc // Author: Josh Winslow // File: cstrikeserv-app.cc // Written: 11/28/01 // #include "cstrikeserv-app.h" // CStrikeServApp OTcl linkage class static class CStrikeServAppClass : public TclClass { public: CStrikeServAppClass() : TclClass("Application/CStrikeServ") {} TclObject* create(int, const charconst) { return (new CStrikeServApp); } } class_app_cstrikeserv; void CSSSendTimer::expire(Event) { t_->send_css_pkt(); } // Constructor CStrikeServApp::CStrikeServApp() : running_(0), css_snd_timer_(this) { } // OTcl command interpreter int CStrikeServApp::command(int argc, const charconst* argv) { Tcl& tcl = Tcl::instance(); if (argc == 3) { if (strcmp(argv[1], "attach-agent") == 0) { agent_ = (Agent) TclObject::lookup(argv[2]); if (agent_ == 0) { tcl.resultf("no such agent %s", argv[2]); return(TCL_ERROR); } } //add filename loading here. } //call superclass? return (Application::command(argc, argv)); } 95 void CStrikeServApp::start() { init(); running_ = 1; gameState_ = 0; send_css_pkt(); } void CStrikeServApp::stop() { running_ = 0; } void CStrikeServApp::init() { tiaTimeIntervals = new timeInterval[TOTAL_INTERVALS]; tiaTimeIntervals[0].burstPct = 5; tiaTimeIntervals[0].burstCoef = 6.00; tiaTimeIntervals[0].minEffSize = 400; tiaTimeIntervals[0].maxEffSize = 610; tiaTimeIntervals[0].outlierPct = 15; tiaTimeIntervals[0].outlierCoef = .5; tiaTimeIntervals[1].burstPct = 5; tiaTimeIntervals[1].burstCoef = 6.00; tiaTimeIntervals[1].minEffSize = 350; tiaTimeIntervals[1].maxEffSize = 550; tiaTimeIntervals[1].outlierPct = 15; tiaTimeIntervals[1].outlierCoef = .5; tiaTimeIntervals[2].burstPct = 5; tiaTimeIntervals[2].burstCoef = 6.00; tiaTimeIntervals[2].minEffSize = 300; tiaTimeIntervals[2].maxEffSize = 500; tiaTimeIntervals[2].outlierPct = 15; tiaTimeIntervals[2].outlierCoef = .5; tiaTimeIntervals[3].burstPct = 5; tiaTimeIntervals[3].burstCoef = 6.00; tiaTimeIntervals[3].minEffSize = 250; tiaTimeIntervals[3].maxEffSize = 450; tiaTimeIntervals[3].outlierPct = 15; tiaTimeIntervals[3].outlierCoef = .5; tiaTimeIntervals[4].burstPct = 5; 96 maxEffSize = 400. tiaTimeIntervals[4]. double rand. }//end if for(int i=0. else pktSize = pktSize -= (int)(pktSizeRandom::uniform(tiaTimeIntervals[curInterval].minEffSize.burstCoef).burstPct) { numPackets = (int)(numPacketstiaTimeIntervals[curInterval]. int numPackets.burstCoef = 6. tiaTimeIntervals[4].1).5). roundTime = 0. }//end for double next_time_ = .5. curInterval = 0. rand = Random::uniform(100). rand = Random::uniform(100). tiaTimeIntervals[4]. if(running_) { numPackets = (int)(Random::uniform(2)+1.5) pktSize = pktSize += (int)(pktSizeRandom::uniform(tiaTimeIntervals[curInterval]. if(rand<tiaTimeIntervals[curInterval]. if(rand>.minEffSize. if( roundTime/(curInterval+1)>20 ) { if(curInterval<TOTAL_INTERVALS-1 ) { curInterval++. roundTime += next_time_.maxEffSizetiaTimeIntervals[curInterval].outlierCoef)). } else { 97 . pktSize += tiaTimeIntervals[curInterval].i++) { pktSize = (int)(Random::uniform(effRange)+. } void CStrikeServApp::send_css_pkt() { int effRange = tiaTimeIntervals[curInterval].outlierPct = 15.00.tiaTimeIntervals[4].1.minEffSize = 200. if(rand<tiaTimeIntervals[curInterval].5).i<numPackets.pktSize. tiaTimeIntervals[4].outlierCoef = .outlierPct) { rand = Random::uniform(0.outlierCoef)). }//if agent_->sendmsg(pktSize). } } css_snd_timer_. }//end if(running_) }//end send_css_pkt 98 .curInterval=0. cout<<"Reset"<<endl.resched(next_time_). print "This process can produce a very large file! You have been warned. 99 . $filename. if($filter eq "1\n") { print "TCP packets will be removed\n".Appendix C – Useful Perl Scripts packet_concatenator. $filter = "udp". $filter). print "This script will concatenate all . $filter = "none". } elsif($filter eq "2\n") { print "UDP packets will be removed\n". ## process command line args and input if(<> eq "y\n") { ## get packet filtering options while(!(($filter eq "tcp") \|\| ($filter eq "udp"))) { print "Select a filtering option:\n1) Filter out all tcp packets\n2) Filter out all udp packets\n3) No filtering\nOption: ".pl Author: Dave LaPointe #!/usr/bin/perl -w use strict. my($currentfile. $filter = "tcp". $filter = <>.\nContinue? (y/n) > ".ccf files in this directory into one file. } elsif($filter eq "3\n") { $filter = "none".\n". {66}11. } ## create the big file open(OUTFILE. 100 . $filename) or die ("Open failed"). ## read it in until(eof CMFILE) { $currentfile . } ## check filter options if($filter eq "tcp") { ## get rid of tcp packets (spots 67 and 68 in file} $currentfile =~ s\|^.ccf")) { $allpackets"). } ## remove excess newlines $currentfile =~ s\|\n\n+\|\n\|g.} else { die "Unrecognized option: ARGV[0]".$\|\|gm. } elsif($filter eq "udp") { ## get rid of udp packets (spots 67 and 68 in file} $currentfile =~ s\|^. print "processing $filename\n". ## open every Commview file in current directory (start a loop) while($filename = glob("\.{66}06. 101 .ccf extension. you should\n". If you choose to add a .## concatenate print OUTFILE $currentfile. } ## final comments print "Files combined into file named \"allpackets\".\n". print "avoid redundancy by removing this file from the current directory before running this script again. $numtimes = 0. $totaltimepackets = 0. $totalsizepackets). "<size.bkt") or die('time. $numtimes.bkt not found\n'). $totalsizepackets = 0. @sizes. (. (.bkt not found\n'). $i++) { $timesline =~ m/^(. $numsizes. $OUTPUT. # get the stuff for($i = 0. "<time. $totaltimepackets += $timenums[$i]. $timenums[$i] = $2. $sizesline = <$SIZES>. $totaltimepackets. @timenums. @times. # open some output files open($OUTPUT. $sizes[$i] = $1. $numsizes = 0. $i++) { $sizesline =~ m/^(. open($SIZES. @sizenums. } for($i = 0. $numsizes++. $timesline = <$TIMES>. $times[$i] = $1. 102 .txt") or die('error opening/creating output file').?)$/. $sizesline. ">code.bkt") or die('size. # get the bucket info open($TIMES. # define some vars my($sizesfilename.?).codegen.pl Author: Dave LaPointe #!/local/usr/bin/perl -w # This script generates code to stuff the contents of a bucket file into GameApp bucket structs use strict. $SIZES.?)$/. $timesfilename. $i. $totalsizepackets += $sizenums[$i]. $value. $numtimes++. $sizenums[$i] = $2. $timesline. $TIMES.?). for($i = 0.} # make code # time deltas array print $OUTPUT 'double temptimes[] = {'. for($i = 0.".\n". $i++) { if($i == ($numtimes-1)) { print $OUTPUT "$times[$i]\}\. for($i = 0. } } # time packet number array print $OUTPUT 'int temptimenums[] = {'. } else { print $OUTPUT "$times[$i]. } else { print $OUTPUT "$timenums[$i].\n". } else 103 . $i < $numtimes.\n". $i++) { if($i == ($numsizes-1)) { print $OUTPUT "$sizes[$i]\}\. $i < $numsizes. $i++) { if($i == ($numtimes-1)) { print $OUTPUT "$timenums[$i]\}\. } } # size array print $OUTPUT 'int tempsizes[] = {'. $i < $numtimes.". \n".push_back(temp).\nint sizeArraySize = $numsizes\. for($i = 0. }EOD 104 . } for(int i = 0. for(int i = 0.". temp->packets = tempsizenums[i]. $i < $numsizes. } } # total packets for each print $OUTPUT "totalTimePackets = $totaltimepackets\. temp->value = temptimes[i]. print $OUTPUT "int timeArraySize = $numtimes\. sizes. } else { print $OUTPUT "$sizenums[$i]. i++) { temp = new bucket. temp->value = tempsizes[i].". $i++) { if($i == ($numsizes-1)) { print $OUTPUT "$sizenums[$i]\}\.\n". i++) { temp = new bucket.\ntotalSizePackets = $totalsizepackets\. # the loop to set it all up print $OUTPUT <<EOD bucket temp. temp->packets = temptimenums[i]. i < sizeArraySize. } } # size packet number array print $OUTPUT 'int tempsizenums[] = {'. times.\n". i < timeArraySize.push_back(temp).{ print $OUTPUT "$sizes[$i]. ">bandwidth.results. } else { print $bwfile "$time. $totalbytes.tr") or die("out. # apps usually start at 1.txt\n").tr not found\n"). $totalbytes = 0. open($outfile.txt") or die ("could not open\/create bandwidth.?) -. # open trace file and output files open($tracefile.0s $totalbytes = 0. $time). $bwfile. $line. # define some vars my($tracefile. $2\n". # handle it all in one loop to conserve memory while($line = <$tracefile>) { if($line =~ m/^\+ (.txt\n").?$/) { print $outfile "$1. $totalbytes\n". if($1 < ($time + 1)) { $totalbytes += $2. ">results.pl Author: Dave LaPointe #!/local/usr/bin/perl -w # This script parses out. $time = 1. $time++. } } } # clean up 105 . . open($bwfile.tr for 2 NODE TOPOLOGIES THAT USE UDP # records the size and time of each packet # records bandwidth for each second in a separate file use strict. "<out. $outfile.txt") or die ("could not open\/create results.?) . udp (. close($tracefile). close($outfile). 106 .	https://www.scribd.com/document/76943857/Analyzing-and-Simulating-Network-Game-Traffic	CC-MAIN-2017-47	refinedweb	20,116	60.21
I have a serious issue with VideoOutput, I can hear the audio but I don’t see the video. I have a PopUp window that has to show a video when opens, but I can only hear it, on the android version does works fine. import Felgo 3.0 import QtQuick 2.0 import QtQuick.Controls 2.1 import QtMultimedia 5.9 ... ... MediaPlayer { id: mediaplayer autoPlay: true loops: MediaPlayer.Infinite source: " } VideoOutput { anchors.fill: parent source: mediaplayer autoOrientation: true fillMode: VideoOutput.PreserveAspectFit } pd. BTW I tried to use the Video component ( and is not recognized, it says ‘Unknow component’ Update: I change the original video source, for the one on the example. But the original video is created on an iphone xr I was playing arround a little with the stop and play methods and I was able to show it but freeze after a few seconds	https://felgo.com/developers/forums/t/videooutput-dosent-work-on-ios	CC-MAIN-2022-21	refinedweb	147	67.25
Sync a WordPress site to Django via the WordPress.com REST API Welcome to django-wordpress-rest! Django-wordpress-rest is a Django application that syncs content from a WordPress.com site to a Django site. This is done using the WordPress.com REST API. A separate copy of the content data is stored on the Django side, which allows for loose coupling and extensability. Full documentation is available on Read The Docs. Install the module: pip install django-wordpress-rest Add "wordpress" to your INSTALLED_APPS setting: INSTALLED_APPS = ( # ... "wordpress", # ... ) Create the database tables that will persist the sync’d WordPress content: $ python manage.py migrate Sync WordPress content using the management command. The <site_id> can be found using the /me/sites WordPress API call. This is useful for periodically updating the content with cron. $ python manage.py load_wp_api <site_id> If you’d like to synchronize private content, create an OAuth2 access token using the instructions provided by WordPress: Add this token to your Django settings.py file. Use an environment variable to keep things secure: WP_API_AUTH_TOKEN = os.getenv("WP_API_AUTH_TOKEN") Bring the site content up to date: # first run gets everything $ python manage.py load_wp_api <site_id> # second run gets content modified since previous run $ python manage.py load_wp_api <site_id> Do a full sweep of the site content, inserting and updating as needed: # first run gets everything $ python manage.py load_wp_api <site_id> # second run gets/updates all content again $ python manage.py load_wp_api <site_id> --full Load everything modified after a given date: $ python manage.py load_wp_api <site_id> --modified_after=2015-01-01 Just load posts, not pages, attachments, or reference data: $ python manage.py load_wp_api <site_id> --type=post Load posts with a specific status (note this requires authentication): $ python manage.py load_wp_api <site_id> --status=draft Purge local content before loading – careful! $ python manage.py load_wp_api <site_id> --purge --full If you’d like to use the webhook to sync a post immediately after it’s updated, include the urls into your project’s urls.py, like so: from django.conf.urls import include urlpatterns = [ url(r'^wordpress/', include('wordpress.urls')) ] Add "after_response" to your INSTALLED_APPS setting (this allows asynchronous processing): INSTALLED_APPS = ( # ... "after_response", "wordpress", # ... ) The webhook looks for your <site_id> in Django settings. So add this your settings.py, and use an environment variable to keep things secure: WP_API_SITE_ID = os.getenv("WP_API_SITE_ID") Finally from your WordPress.com site, submit a POST request with an ID data element in the body to trigger a sync of a single post. Note this should be the WordPress Post ID, not the Django one! $ curl -X POST --data "ID=123456" $ pip install detox $ detox Download the file for your platform. If you're not sure which to choose, learn more about installing packages.	https://pypi.org/project/django-wordpress-rest/	CC-MAIN-2017-26	refinedweb	454	59.7
Chatlog 2011-01-27 From RDFa Working Group Wiki See CommonScribe Control Panel, original RRSAgent log and preview nicely formatted version. 14:54:27 <RRSAgent> RRSAgent has joined #rdfa 14:54:27 <RRSAgent> logging to 14:54:29 <trackbot> RRSAgent, make logs world 14:54:29 <Zakim> Zakim has joined #rdfa 14:54:31 <trackbot> Zakim, this will be 7332 14:54:31 <Zakim> ok, trackbot; I see SW_RDFa()10:00AM scheduled to start in 6 minutes 14:54:32 <trackbot> Meeting: RDFa Working Group Teleconference 14:54:32 <trackbot> Date: 27 January 2011 15:00:00 <Knud> Knud has joined #rdfa 15:00:11 <Zakim> SW_RDFa()10:00AM has now started 15:00:19 <Zakim> + +3539149aaaa 15:00:27 <Knud> zakim, I am aaaa 15:00:27 <Zakim> +Knud; got it 15:00:36 <manu1> Agenda: 15:00:38 <manu1> Chair: Manu 15:00:56 <manu1> Present: Ivan, Benjamin, Manu, Knud, MarkB, ShaneM, Nathan, Steven 15:00:59 <ivan> zakim, dial ivan-voip 15:00:59 <Zakim> ok, ivan; the call is being made 15:01:00 <Zakim> -Knud 15:01:00 <Zakim> +Knud 15:01:00 <Zakim> +Ivan 15:01:09 <markbirbeck> markbirbeck has joined #rdfa 15:01:30 <Zakim> +??P54 15:01:36 <manu1> zakim, I am ??P54 15:01:36 <Zakim> +manu1; got it 15:02:42 <manu1> zakim, who is on the call? 15:02:42 <Zakim> On the phone I see Knud, Ivan, manu1 15:03:29 <markbirbeck> zakim, code? 15:03:29 <Zakim> the conference code is 7332 (tel:+1.617.761.6200 tel:+33.4.26.46.79.03 tel:+44.203.318.0479), markbirbeck 15:04:16 <ShaneM> ShaneM has joined #rdfa 15:04:19 <Zakim> + +200000aabb 15:04:24 <markbirbeck> zakim, i am aabb 15:04:24 <Zakim> +markbirbeck; got it 15:04:27 <Zakim> + +1.612.217.aacc 15:05:08 <manu1> zakim, mute knud 15:05:08 <Zakim> Knud should now be muted 15:05:39 <manu1> zakim, who is on the call? 15:05:39 <Zakim> On the phone I see Knud (muted), Ivan, manu1, markbirbeck, +1.612.217.aacc 15:06:02 <ivan> zakim, aacc is ShaneM 15:06:02 <Zakim> +ShaneM; got it 15:06:22 <ivan> zakim, mute me 15:06:22 <Zakim> Ivan should now be muted 15:06:39 <ivan> scribenick: ivan 15:06:58 <ivan> manu1: is it necessary to discuss the issue of default profile 15:07:12 <ivan> ... this may be a good idea in discussing with html5 15:07:28 <ivan> ... let us do the editorial issues first 15:07:46 <ivan> manu1: shane, did you look at steven's editorial issues? 15:07:54 <manu1> Topic: Approving Editorial suggestions? 15:07:57 <manu1> 1) Approve editorial suggestions? 15:07:58 <ivan> ShaneM: yes I have 15:07:58 <manu1> ISSUE-71: Shelley Power's LC comments 15:08:00 <manu1> 15:08:01 <manu1> 15:08:03 <manu1> ISSUE-79: Integrate CURIE information 15:08:05 <manu1> 15:08:06 <Steven_> Steven_ has joined #rdfa 15:08:07 <manu1> ISSUE-80: Integrate attribute information 15:08:09 <manu1> 15:08:11 <manu1> ISSUE-81: Make declarative definition normative, procedural 15:08:11 <ivan> manu1: what do you think are they ok? 15:08:12 <manu1> definition informative. 15:08:14 <manu1> 15:08:50 <Steven_> zakim, dial steven-617 15:08:50 <Zakim> ok, Steven_; the call is being made 15:08:51 <ivan> Topic: ISSUE-79: Editorial merging sections on CURIEs 15:08:52 <manu1> 15:08:53 <Zakim> +Steven 15:09:10 <ivan> ... take issue 79: to merge some curie information 15:09:13 <Steven_> Sorry for being late, I was on another call, and missed the time 15:09:14 <ivan> ... my reaction is no 15:09:42 <ivan> ... we need a free standing curie section which is not only rdfa 15:09:52 <ivan> ... merging the sections would be problematic 15:10:17 <manu1> 15:10:22 <ivan> ... section 3.8 is a historical section that mark wrote back in the day to justify curie-s 15:10:42 <ivan> ... it does not really say anything about them and it is not normative 15:10:48 <ivan> ... i would prefer to let them alone, too 15:11:03 <ivan> manu1: essentially, issue 79 suggestion is to leave that as it is 15:11:04 <Steven_> Iḿ OK with that 15:11:05 <ivan> ShaneM: yep 15:11:17 <ivan> (WG accepted) 15:11:28 <Zakim> -manu1 15:11:45 <Zakim> +[IPcaller] 15:12:02 <ivan> Topic: ISSUE-80: Editorial - Integrate attribute datatype information 15:12:11 <manu1> ISSUE-80 - Integrate attribute information - 15:12:11 <trackbot> ISSUE-80 Editorial - Integrate attribute information. Triage of Issue 75 - Part 2 notes added 15:12:23 <ivan> .... the commenter is concerned that normative definitions and datatypes are scattered all over the place 15:12:29 <ivan> ... it was not true, but it might be true now 15:12:46 <ivan> ... section 8 has a lot of info, but it does not define any datatype (section 5) 15:12:58 <ivan> ... my proposal is to make it so that section 5 is complete 15:13:10 <ivan> ... it defined the attributes and syntax 15:13:54 <ivan> ... section 7.4.4., which is part of a larger section on curie and uri processing, I would be happy to remove 15:14:03 <ivan> ... it is defined in section (or it should be) 15:14:15 <manu1> zakim, I am [IPcaller] 15:14:15 <Zakim> ok, manu1, I now associate you with [IPcaller] 15:14:23 <manu1> zakim, who is on the call? 15:14:23 <Zakim> On the phone I see Knud (muted), Ivan (muted), markbirbeck, ShaneM, Steven, [IPcaller] 15:14:24 <ivan> ... mark, is it o.k with you? 15:14:43 <ivan> markbirbeck: it is fine with me; it is a self contained part, though 15:15:03 <ivan> ... but it is indeed a summary 15:15:11 <ivan> ... it does not add anything 15:15:28 <ivan> ShaneM: as it stands now, you have to read it 15:15:39 <ivan> ... it does not say what that datatype says 15:15:44 <ivan> ... it is safe to remove it 15:15:58 <ivan> manu1: agree with that 15:16:06 <ivan> ... any objection to remove that section? 15:16:17 <ivan> markbirbeck: how do we feel about other sections? 15:16:27 <ivan> manu1: nobody complained about other sections... 15:16:36 <ivan> ... so, maybe we can look through those 15:16:45 <ivan> ... at present we do not have any issues about this 15:17:08 <ivan> ShaneM: mark, if you have a strong objection, my alternative is to fix 7.4.4 15:17:21 <ivan> ... right now it is a bit coloquial 15:17:39 <ivan> markbirbeck: I do not have a strong objection, but, eg, 7.4.2 does it look any better? 15:17:49 <ivan> ... jenni would like to have everything in one place 15:17:54 <ivan> ... which makes sense 15:18:07 <ivan> ... if it is possible to fix 7.4.4 rather, I would prefer this a bit 15:18:23 <ivan> ... I am happy either way, I let shane decide 15:18:40 <ivan> ShaneM: mark, I agree that 7.2.2 has the same problem as 7.2.4 has, it is imprecise 15:19:00 <ivan> ... fixing it would mean referencing the datatypes back to the absolute definitions 15:19:26 <ivan> ... we are not referencing it here, there is no tie 15:20:04 <ivan> manu: there is also something here that says to make 7.4.4. non normative and the other normative 15:20:14 <ivan> ... that approach goes into the next issue we are talking about 15:20:49 <ivan> ... shane, do you agree making these explanatory section non-normative? This ties in into the next section 15:20:58 <ivan> ShaneM: she wanted section 8 to be non-normative 15:21:14 <ivan> ... section 7 there is no section I would make non-normative, it is important for implementers 15:21:25 <ivan> .... section 8 is more something like a test suite 15:21:36 <ivan> ... it gave me a bunch of examples 15:21:56 <ivan> ... I would defer to mark on whether section 8 should be non-normative 15:22:16 <ivan> manu: I trust you, shane, to make the right decision 15:22:52 <ivan> ... talking about issue 80, shane offers to point back to the datatypes from the prose 15:23:08 <ivan> ShaneM: the same for 7.4.4 15:23:14 <ivan> ... they both need those tie-back 15:23:21 <ivan> manu: any objection? 15:23:23 <ivan> ... 15:23:26 <ivan> (WG agreed) 15:23:27 <ivan> Topic: ISSUE-81: Make section 7 normative, section 8 non-normative 15:23:29 <manu1> ISSUE-81 Make declarative definition normative, procedural definition informative, 15:23:46 <ivan> Steven_: I agree with her about this 15:24:09 <ivan> ... if we agree that 7.5 and 8 are overlapping, I agree making one normative and the other informative, advise for implementations 15:24:20 <ivan> ShaneM: I said I would defer to mark... 15:24:34 <ivan> markbirbeck: ... but you hinted it is a good idea:-) 15:24:40 <manu1> 15:24:55 <ivan> ... the original idea was that one was a friendly explanation of section 7 15:25:03 <ivan> ... if we are sure that everything is covered 15:25:23 <ivan> ... then shane's suggestion (section 8 is informative, section 7 normative) is fine 15:25:58 <ivan> manu: when I did my implementation than I just implemented the process 15:26:05 <ivan> ... and then looking at the examples 15:26:33 <ivan> ShaneM: we are making so many changes that we will have a 2nd last call:-) 15:26:47 <ivan> ... I am not worried about the change 15:27:03 <ivan> ... I will have to make a cleaner implementation before 2nd last call 15:27:14 <ivan> q+ 15:28:06 <ivan> manu: from a design standpoint this is the right thing to do, if we find an issue 15:28:08 <manu1> ack ivan 15:28:09 <ivan> ack ivan 15:28:31 <manu1> Ivan: I used Section 7 almost exclusively for my implementation. 15:28:38 <manu1> Ivan: I used section 8 for checking my understanding. 15:28:57 <ivan> manu: any objection to follow shane's offer, section 8 non-normative? 15:28:58 <ivan> .... 15:29:02 <ivan> (WG accepted) 15:29:05 <ivan> zakim, mute me 15:29:05 <Zakim> Ivan should now be muted 15:29:15 <ivan> Topic: ISSUE-71: Last Call Comments from Shelley Powers 15:29:15 <ivan> manu1: last issue is Shelley's comments 15:29:20 <manu1> 15:29:24 <ivan> ... everything that she had was editorial 15:29:32 <manu1> ISSUE-71 15:29:35 <ivan> ... and they were not as heavy as Jeni's 15:29:46 <ivan> ISSUE-71? 15:29:46 <trackbot> ISSUE-71 -- RDFa Core 1.1 LC comments from Shelley Powers -- open 15:29:46 <trackbot> 15:30:02 <ivan> ShaneM: sorry, I did not have time to look at those, let us skip those 15:30:14 <ivan> Topic: ISSUE-78: Prefixes and terms in one default RDFa Profile for all Host languages 15:30:14 <ivan> ISSUE-78? 15:30:14 <trackbot> ISSUE-78 -- Should we have default prefixes and terms for host languages -- open 15:30:14 <trackbot> 15:30:29 <ShaneM> 15:31:10 <manu1> ISSUE-73? 15:31:10 <trackbot> ISSUE-73 -- The RDFa WG needs to determine how each RDFa Profile document is managed -- open 15:31:10 <trackbot> 15:31:15 <ivan> manu1: it is the whole issue of the default profile, what goes there, etc 15:31:20 <ivan> zakim, unmute me 15:31:20 <Zakim> Ivan should no longer be muted 15:31:31 <manu1> Ivan: There are several sub-issues here 15:31:45 <manu1> Ivan: Do we want a default profile in the first place? 15:32:01 <manu1> Ivan: Is the content of the default profile frozen at the time of REC? 15:32:21 <manu1> Ivan: Is there a community-driven mechanism that allows people to add to the default profile over time? 15:32:32 <manu1> Ivan: In case we have a community-driven mechanism, what is it? 15:32:38 <Steven_> q+ 15:32:42 <manu1> Ivan: These are all related 15:34:20 <manu1> Ivan: Do we want to have Dublin Core, FOAF, prefixes defined in the default profile for RDFa? 15:34:55 <manu1> Manu: Do we want to have a single RDFa default profile for all languages? 15:35:35 <manu1> Ivan: Do prefixes defined in the default profile scale? What about UAs that can't cache the profiles? 15:35:56 <manu1> ack Steven_ 15:37:30 <manu1> Steven: I think RDFa does the right thing - we allow caching... registries are problematic. 15:37:40 <manu1> Ivan: Authors sometimes don't put in the namespace declarations. 15:37:50 <manu1> I have a proposal: 15:38:02 <manu1> We have 1 RDFa default profile for all languages. 15:38:19 <manu1> We allow new prefixes to be registered up until RDFa Core 1.1 goes to REC. 15:38:23 <manu1> same with terms. 15:38:41 <manu1> We don't allow new prefixes to be added to the RDFa default profile document after REC. 15:38:57 <manu1> but we do allow items to be suggested for the next revision of RDFa Core. 15:39:31 <manu1> q+ 15:39:42 <manu1> zakim, [IPcaller] is me 15:39:42 <Zakim> +manu1; got it 15:39:45 <manu1> q? 15:40:46 <manu1> For a vocabulary to be included in the default profile, it must exhibit 15:40:48 <manu1> at least the following: 15:40:49 <manu1> 1. Be long-lived, use a URL redirecting service, or be controlled by an 15:40:51 <manu1> organization that could ensure that the vocabulary stay reachable 15:40:52 <manu1> for 10+ years or more. 15:40:54 <manu1> 2. Be of general use to web developers (so, rdf, rdfa, xsd, foaf, dc 15:40:55 <manu1> would make the cut... unsure about skos and owl). 15:40:57 <manu1> 3. Be well documented, designed well and in use by a community that 15:40:58 <manu1> can demonstrate that the vocabulary will be maintained for 10+ years. 15:41:19 <ShaneM> q+ to discuss profile evolution 15:41:42 <ivan> manu1: these are all issues, high level thoughts from everybody? 15:42:02 <ivan> Manu: I have put in irc my own approach 15:42:11 <ivan> ... we used to talk about xml, svg, etc profiles 15:42:30 <ivan> ... but what ivan put in on the mailing list to have only one default profile 15:42:42 <ivan> ... that would simplify things, only one profile is relevant 15:42:50 <ivan> ... I think that is a good idea 15:43:10 <ivan> ... as far as community managed registry: I think it would be a massive headache to have something that works for everyone 15:43:30 <ivan> ... if we agree to have that, we have to talk to the players 15:43:42 <ivan> ... this should be fixed 15:43:56 <ivan> ... when the rec are published 15:43:59 <ivan> q+ 15:44:11 <ivan> ... and have some sort of a mechanism to update? 15:44:31 <manu1> ack [IPcaller] 15:44:35 <markbirbeck> q+ 15:45:42 <ivan> manu1: proposal would be to take one registry, update it every X years, but not absolutely dynamic 15:45:43 <manu1> ack shaneM 15:45:43 <Zakim> ShaneM, you wanted to discuss profile evolution 15:46:04 <ivan> ShaneM: you suggest that host languages would not have a default profiles 15:46:24 <ivan> manu1: we would have one default profile for all our languages 15:46:37 <ivan> ShaneM: that would not solve things 15:46:46 <ivan> ... we have no announcement mechanism 15:46:59 <ivan> ... I would modify your proposal to say that host languages cannot define their own profile 15:47:02 <manu1> ack ivan 15:47:40 <manu1> ack markbirbeck 15:48:14 <ivan> markbirbeck: one problem is to have a uri to profile that keeps changing 15:48:26 <ivan> ... one step would be to freeze a profile but also freeze the uri 15:48:27 <manu1> 15:48:31 <manu1> 15:48:40 <ivan> ... based on a date 15:48:44 <ivan> ... which could then be changed 15:48:49 <manu1> 15:48:57 <ivan> ... what people want is that the profile attribute would not be specified 15:49:18 <ivan> ... you then allow people to refer to a profile specificly 15:49:22 <ivan> q+ 15:49:38 <manu1> I like that suggestion, Mark 15:49:46 <ivan> ... but we have the possibility to have a default profile for a language 15:49:59 <ivan> ... or default value for the profile attribute is XXX 15:50:21 <ivan> ... that gets round the moving thing 15:50:31 <ivan> ... but we talk about caching 15:50:51 <manu1> I agree that we need to hardcode profiles into processors... 15:50:56 <ivan> ... but always thoughts is that much more likely scenario is that people will hard code profiles 15:51:07 <ivan> ... and then if you take that in context 15:51:12 <manu1> you don't need to, but I think that's what most implementations are going to do. 15:51:27 <ivan> ... in the original version we had the idea of profiles referring to other profiles 15:51:44 <ivan> ... that would give a much more dynamic features 15:52:02 <ivan> ... drupal could create a profile that would aggregate another profile 15:52:04 <ivan> ... etc 15:52:09 <ivan> q+ 15:52:26 <manu1> I have issues w/ recursively sucking in profiles. 15:52:28 <manu1> ack ivan 15:53:21 <manu1> Ivan: What this means is that every 2 years, W3C would open a new group to revise profiles. 15:53:28 <manu1> Ivan: I don't think that's feasible. 15:53:53 <markbirbeck> @manu: I would say that's because you're seeing profiles� as something to be loaded on the fly. :) 15:54:44 <manu1> Ivan: If we can issue a new profile every 2 years, we make noise about it, implementers will have to update their implementations (hardcoded or not) 15:55:04 <manu1> Ivan: I don't think we should bind these two things together - profiles having a dated URI vs. non-dated URI is a good idea. 15:55:16 <manu1> Ivan: That's slightly orthogonal, though. 15:55:26 <manu1> q? 15:55:44 <ivan> markbirbeck: I think that we should not use the latest URI, we should always require an explicit URI 15:55:53 <ivan> ... you do not gain the latest 15:56:26 <manu1> zakim, who is on the phone? 15:56:26 <Zakim> On the phone I see Knud (muted), Ivan, markbirbeck, ShaneM, Steven, manu1 15:56:45 <ivan> ShaneM: mark, to expand on someting you said 15:56:56 <ivan> ... assuming we had dated URI-s as profiles as they evolve 15:57:21 <ivan> ... would you expect implementation to hardcode all of those, so that pages that have explicit references to one would get it 15:57:45 <ivan> markbirbeck: well... I am picturing that there is a new release of a new ontology 15:57:57 <ivan> ... then w3c creates a new profile with the new ontology 15:58:08 <ivan> ... the only reason an implementer might hard code it 15:58:23 <ivan> ... it is only for if somebody uses that explicitly 15:58:37 <ivan> ... whether this finds its way into an rdfa language 15:58:45 <ivan> ... so we would just refer to the latest 15:58:57 <ivan> ... in the rdfa document 15:59:05 <ivan> ... implementers may choose how they do it 15:59:37 <ivan> manu1: we should have a super session of LC 15:59:49 <ivan> .. our list is growing and we shall fill up the whole of february 15:59:53 <manu1> 16:00:07 <ivan> ... please put up your availability 16:00:13 <ivan> ... hopefully close a lot of them 16:01:23 <manu1> Should we have one default profile for all RDFa languages? Any objections? 16:03:09 <manu1> Shane: No objection, do you think it will work for HTML WG? 16:04:46 <manu1> PROPOSAL: RDFa 1.1 will have one default profile for all Host languages. 16:05:10 <ShaneM> +1 - NOTE that it might be a 'default default profile' 16:05:15 <manu1> +1 16:05:24 <Knud> +1 16:05:24 <ivan> Ivan: +1 16:05:25 <Steven_> +0 16:05:31 <markbirbeck> +1 16:05:39 <manu1> RESOLVED: RDFa 1.1 will have one default profile for all Host languages. 16:08:40 <manu1> PROPOSAL: RDFa WG will define a set of prefixes and terms for the default profile, those prefixes/terms will be frozen at REC (a mechanism will be setup to update the default profile before RDFa Core goes to REC) 16:09:33 <ivan> PROPOSAL: RDFa WG will define a set of prefixes and terms for the default profile; a mechanism will be setup to update the default profile before RDFa Core goes to REC 16:10:26 <ivan> PROPOSAL: RDFa WG will define a set of prefixes and terms for the default profile; a mechanism will be proposed to update the default profile 16:10:41 <markbirbeck> +1 16:10:46 <ivan> Ivan: +1 16:10:49 <manu1> +1 16:11:50 <manu1> zakim, who is on the call? 16:11:50 <Zakim> On the phone I see Knud (muted), Ivan, markbirbeck, ShaneM, Steven, manu1 16:11:51 <Knud> +1 16:11:57 <ShaneM> +1..... 16:13:02 <manu1> RESOLVED: RDFa WG will define a set of prefixes and terms for the default profile; a mechanism will be proposed to update the default profile 16:14:18 <markbirbeck> What about: PROPOSAL: RDFa WG will define a profile with a set of prefixes and terms, and this profile will be referenced as the default profile. A mechanism will also be proposed for creating additional profiles which can be referenced as the default profile for future versions of RDFa. 16:16:12 <Steven_> +1 16:18:01 <Zakim> -Knud 16:18:06 <Knud> Knud has left #rdfa 16:18:54 <Zakim> -markbirbeck 16:19:15 <markbirbeck> @Ivan: What you seek is simply not possible. 16:19:46 <markbirbeck> And it would be a major mistake to try to achieve it by having a profile that can change at any time. 16:19:55 <webr3> just fyi, js3 has over 100 prefixes defined by default, and in the past two weeks I've had 4 requests to add more to the default profile, including one two seconds ago to add bibo 16:20:05 <manu1> 16:20:20 <markbirbeck> It makes caching "meaningless", since you can't reliably cache. 16:20:40 <manu1> 16:20:59 <markbirbeck> It makes hard-coding into phones and small devices meaningless, too. 16:21:00 <manu1> RDFa 1.1 => default profile => 16:21:22 <markbirbeck> (BTW, not sure why I got dropped...the phone went dead on me.) 16:21:28 <manu1> RDFa 2.0 => default profile => 16:21:39 <ShaneM> q+ to discuss process 16:21:46 <manu1> ack shanem 16:21:46 <Zakim> ShaneM, you wanted to discuss process 16:24:09 <manu1> q+ 16:25:13 <webr3> RDFa 1.1 processors must recognise the following prefixes: x,y,z - this list is also available as an RDFa Profile here: http://..... (then repeat for each new spec) 16:26:34 <manu1> ack 16:26:39 <manu1> ack manu1 16:27:10 <manu1> we seem to be coming to some sort of consensus: 16:29:27 <manu1> We bind RDFa 1.1 profile to a dated URL. 16:30:59 <manu1> For example: 16:31:12 <manu1> That profile could be updated every 2+ years 16:31:27 <manu1> RDFa 1.1 is bound to that URL as the default profile 16:32:40 <manu1> 16:34:23 <Zakim> -manu1 16:34:24 <ivan> zakim, drop me 16:34:24 <Zakim> -ShaneM 16:34:24 <Zakim> Ivan is being disconnected 16:34:28 <Zakim> -Ivan 16:34:32 <Zakim> -Steven 16:34:34 <Zakim> SW_RDFa()10:00AM has ended 16:34:38 <Zakim> Attendees were +3539149aaaa, Knud, Ivan, manu1, +200000aabb, markbirbeck, +1.612.217.aacc, ShaneM, Steven # SPECIAL MARKER FOR CHATSYNC. DO NOT EDIT THIS LINE OR BELOW. SRCLINESUSED=00000354	http://www.w3.org/2010/02/rdfa/wiki/Chatlog_2011-01-27	CC-MAIN-2016-18	refinedweb	4,171	70.33
Re: Grey Market Question. - From: "Jeremy" <jeremy@xxxxxxxxxx> - Date: Sun, 30 Apr 2006 14:13:32 GMT "Father Kodak" <dont_bother@xxxxxxxxxxxxx> wrote in message news:smv452pi36c6fv9pb1fh6ckqa5ggbbg3ca@xxxxxxxxxx So what is the situation specifically for Nikon if you: -Are a US citizen -Are in another country, say Japan -Buy some Nikon gear in Tokyo, say at Yodobashi or Doi or Sakuyara. As a foreigner, you avoid paying local taxes or get a rebate at the airport when you leave. -After you get home, your gear needs a repair, within the one year warranty period. So, what will Nikon USA do? Will they even refuse to repair the item, even if you paid for the repair (as I have heard it)? WHO ISSUED THE WARRANTY ON YOUR CAMERA GEAR? NIKON USA OR SOME OTHER ENTITY? When I bought Honeywell Pentax equipment, there was a provision for repairs to be made for international customers that bought through the official importer in whatever country they were in. Pentax issued an International Warranty, and the official importers honored it on a reciprocal basis. Now, if you buy outside the US, and you self-import, Nikon has no LEGAL OBLIGATION under US law to provide warranty service, since they did not import the goods. They may, however, have a reciprocal agreement with the other country's importer. My point is that one should not assume that they are entitled to service or support from any entity except that which issued the original warranty. You do not have the legal RIGHT to have your cake and eat it, too. If Nikon USA elects to provide you with service it is due to factors other than any legal requirement. Perhaps you should choose another manufacturer, with less stringent enforcement policies. The choice is yours. . - References: - Grey Market Question. - From: Ruman - Re: Grey Market Question. - From: Walter Banks - Re: Grey Market Question. - From: Jeremy - Re: Grey Market Question. - From: Geoffrey S. Mendelson - Re: Grey Market Question. - From: Father Kodak - Prev by Date: Re: OT - Supply side solution for oil energy bound to fail. - Next by Date: Re: OT - Supply side solution for oil energy bound to fail. - Previous by thread: Re: Grey Market Question. - Next by thread: Re: Grey Market Question. - Index(es):	http://newsgroups.derkeiler.com/Archive/Rec/rec.photo.equipment.35mm/2006-04/msg01617.html	crawl-002	refinedweb	374	66.23
Description A Python library for offline reverse geocoding. It improves on an existing library called reverse_geocode developed by Richard Penman. The library was built with speed in mind and it can geocode 10 million GPS coordinates in under 30 seconds on a machine with 8 cores. Reverse Geocoder alternatives and similar packages Based on the "Geolocation" category. Alternatively, view Reverse Geocoder alternatives based on common mentions on social networks and blogs. geopy7.7 8.3 L5 Reverse Geocoder VS geopyGeocoding library for Python. Shapely6.9 7.4 L3 Reverse Geocoder VS ShapelyManipulation and analysis of geometric objects geocoder5.8 0.0 L5 Reverse Geocoder VS geocoder:earth_asia: Python Geocoder django-countries5.0 7.1 L4 Reverse Geocoder VS django-countriesA Django application that provides country choices for use with forms, flag icons static files, and a country field for models. geoip24.4 6.1 L5 Reverse Geocoder VS geoip2Python code for GeoIP2 webservice client and database reader geojson4.1 2.9 L4 Reverse Geocoder VS geojsonPython bindings and utilities for GeoJSON pygeoip3.9 0.0 L4 Reverse Geocoder VS pygeoipPure Python GeoIP API. GeoIP2.9 1.5 L4 Reverse Geocoder VS GeoIPGeoIP Legacy Python API GeoDjango1.0 0.0 L3 Reverse Geocoder VS GeoDjangoGeoDjango provides geospatial extensions to the Django web dev Reverse Geocoder or a related project? README Reverse Geocoder A Python library for offline reverse geocoding. It improves on an existing library called reverse_geocode developed by Richard Penman. UPDATE (15-Sep-16): v1.5.1 released! See release notes below. About Ajay Thampi \| @thampiman \| opensignal.com \| ajaythampi.com Features - Besides city/town and country code, this library also returns the nearest latitude and longitude and also administrative regions 1 and 2. - This library also uses a parallelised implementation of K-D trees which promises an improved performance especially for large inputs. By default, the K-D tree is populated with cities that have a population > 1000. The source of the data is GeoNames. You can also load a custom data source so long as it is a comma-separated file with header (like rg_cities1000.csv), containing the following columns: lat: Latitude lon: Longitude name: Name of place admin1: Admin 1 region admin2: Admin 2 region cc: ISO 3166-1 alpha-2 country code For usage instructions, see below. Installation For first time installation, $ pip install reverse_geocoder Or upgrade an existing installation using, $ pip install --upgrade reverse_geocoder Package can be found on PyPI. Dependencies - scipy - numpy Release Notes - v1.0 (27-Mar-15) - First version with support for only Python2 - v1.1 (28-Mar-15) - Fix for issue #1 by Brandon - v1.2 (30-Mar-15) - Support for Python 3, conversion of Geodetic coordinates to ECEF for use in K-D trees to find nearest neighbour using the Euclidean distance function. This release fixes issues #2 and #8. Special thanks to David for his help in partly fixing #2. - v1.3 (11-Apr-15) - This release fixes issues #9, #10, #11 and #12. License has been changed from MIT to LGPL (see #12). - v1.4 (08-Jul-16) - Included numpy and scipy as dependencies in setup. - v1.5 (15-Sep-16) - Support for custom data source and fixes for issues #16 and #24. Hat tip to Jason and Gregoire. - v1.5.1 (15-Sep-16) - Fix for #26. Usage The library supports two modes: - Mode 1: Single-threaded K-D Tree (similar to reverse_geocode) - Mode 2: Multi-threaded K-D Tree (default) import reverse_geocoder as rg coordinates = (51.5214588,-0.1729636),(9.936033, 76.259952),(37.38605,-122.08385) results = rg.search(coordinates) # default mode = 2 print results The above code will output the following: [{'name': 'Bayswater', 'cc': 'GB', 'lat': '51.51116', 'lon': '-0.18426', 'admin1': 'England', 'admin2': 'Greater London'}, {'name': 'Cochin', 'cc': 'IN', 'lat': '9.93988', 'lon': '76.26022', 'admin1': 'Kerala', 'admin2': 'Ernakulam'}, {'name': 'Mountain View', 'cc': 'US', 'lat': '37.38605', 'lon': '-122.08385', 'admin1': 'California', 'admin2': 'Santa Clara County'}] If you'd like to use the single-threaded K-D tree, set mode = 1 as follows: results = rg.search(coordinates,mode=1) To use a custom data source for geocoding, you can load the file in-memory and pass it to the library as follows: import io import reverse_geocoder as rg geo = rg.RGeocoder(mode=2, verbose=True, stream=io.StringIO(open('custom_source.csv', encoding='utf-8').read())) coordinates = (51.5214588,-0.1729636),(9.936033, 76.259952),(37.38605,-122.08385) results = geo.query(coordinates) As mentioned above, the custom data source must be comma-separated with a header as rg_cities1000.csv. Performance The performance of modes 1 and 2 are plotted below for various input sizes. [Performance Comparison](performance.png) Mode 2 runs ~2x faster for very large inputs (10M coordinates). Acknowledgements - Major inspiration is from Richard Penman's reverse_geocode library - Parallelised implementation of K-D Trees is extended from this article by Sturla Molden - Geocoded data is from GeoNames License Copyright (c) 2015 Ajay Thampi and contributors. This code is licensed under the LGPL License. *Note that all licence references and agreements mentioned in the Reverse Geocoder README section above are relevant to that project's source code only.	https://python.libhunt.com/reverse-geocoder-alternatives	CC-MAIN-2021-25	refinedweb	854	58.38
class Solution: # @param n, an integer # @return an integer def hammingWeight(self, n): return bin(n)[2:].zfill(32).count('1') Here is my one- line solution to the above problem. LMK if I optimize this further somewhere. edit: Above was my first solution, I quickly realized that I dont have to make it a 32 bit integer . I got rid of the zfill , and my solution is down to 48 ms. My solution is now as below. class Solution: # @param n, an integer # @return an integer def hammingWeight(self, n): return bin(n)[2:].count('1') def hammingWeight(self, n): p = bin(n) return sum((n=='1') for n in p[2:]) generator list of n=='1' and then sum the array of true/false. Seems slightly faster than count. Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.	https://discuss.leetcode.com/topic/10235/54-ms-python-one-line-solution-edit-48-ms-now	CC-MAIN-2018-05	refinedweb	147	66.94
I had an instance at work where I needed to quickly calculate an estimate for Reynolds Number for 0 gallons/min to 10 gallons/min for several different pipe diameters. At first, I tried this by hand. With various unit conversions, I got something wrong and ended up off by about 50%. Enter Python and Pint. You probably already know about Python, but Pint is a very handy little package that keeps track of your units as you are going through, including through math operations. This keeps you from messing things up due to a simple unit conversion error. First, we set ourselves up: import pint from math import pi unit = pint.UnitRegistry() # create the unit registry We then define our central calculation, implementing the formula above. Note the .to() method that is being utilized to get the units consistent. Pint will often resolve simple operations itself - unit.inch * unit.meter will result in inch 2 - but Pint is not a symbolic math engine, it just cancels the appropriate units that are obvious and leaves the rest out there. As a result, your answer may be technically correct, but useless with mixed units everywhere if you don't use the .to() method. def calc_reynolds_number(volumetric_flow_rate, hydraulic_diameter, kinematic_viscocity, cross_sectional_area): q = volumetric_flow_rate.to('meter 3 / s') dh = hydraulic_diameter.to('meter') v = kinematic_viscocity.to('meter 2 / second') a = cross_sectional_area.to('meter 2') re = (q * dh) / (v * a) return re As it turns out, the presented example results in the same exact output if the function were re-written: def calc_reynolds_number(volumetric_flow_rate, hydraulic_diameter, kinematic_viscocity, cross_sectional_area): re = (volumetric_flow_rate * hydraulic_diameter) / (kinematic_viscocity * cross_sectional_area) return re So there's one point for Pint. I have had the non-conversion bite me in the past, so I always convert to my preferred units. Finally, we need to actually perform our calculations and show the results: if __name__ == '__main__': viscosity = 0.000001 * unit.meter ** 2 / unit.second cross_sectional_area = pi * (0.5 * unit.inch) ** 2 diameter = 2.0 * unit.inch for i in range(11): volumetric_flow_rate = i * unit.gallons / unit.minute re = calc_reynolds_number(volumetric_flow_rate, diameter, viscosity, cross_sectional_area) print('{}\t{}'.format(volumetric_flow_rate, int(re))) This results in an output of: 0.0 gallon / minute 0 1.0 gallon / minute 6325 2.0 gallon / minute 12650 3.0 gallon / minute 18975 4.0 gallon / minute 25300 5.0 gallon / minute 31625 6.0 gallon / minute 37950 7.0 gallon / minute 44275 8.0 gallon / minute 50600 9.0 gallon / minute 56926 10.0 gallon / minute 63251 Which I can easily copy/paste into my favorite spreadsheet editor!	http://forembed.com/reynolds-number-with-python-and-pint.html	CC-MAIN-2018-51	refinedweb	424	52.36
The problem is that autocomplete and snippet completion are both bound to <Tab> but often conflict. As a simple example, in a Ruby document: - Code: Select all def<Tab>run gives me the following code, with the cursor at the indicated point: - Code: Select all def run❚ end Now, in most places in the document, hitting <Tab> at the current cursor position would autocomplete `run` to `running_process` (assuming that phrase is the closest available match, which in this case it is). But because I'm still in "snippet mode", the <Tab> actually skips me to the method body: - Code: Select all def run ❚ end There seems to be no way to choose indicate to Sublime that I want to use autocomplete at that point. In Textmate this wasn't an issue because <Tab> was reserved for snippets and <Esc> was the autocomplete trigger - which makes sense to me, because two features which might be available at the same time shouldn't share the same key. Is there a way to change one of these triggers to a different key, or do I need to change how I'm thinking somehow?	http://www.sublimetext.com/forum/viewtopic.php?p=26273	CC-MAIN-2014-15	refinedweb	190	51.04
Hi everybody, i’m rework my app and i’m using UISplitviewController. before iOS 14 you did can use delegate method and the split view showed master view. import UIKit class CustomSplitViewController: UISplitViewController, UISplitViewControllerDelegate { override func viewDidLoad() { super.viewDidLoad() delegate = self preferredDisplayMode = .allVisible } /* //. } */ func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController:UIViewController, onto primaryViewController:UIViewController) -> Bool { return true } } But now, that code doesn’t work. Both iPhone and iPad is showed only detail view. i’m using Storyboard and i’ve set “Display mode” to “Two Columns Beside” and “Behavior” to “Tile” how can i make the split view show the master view? Thanks p.s. I’ve tested one thing: if you use a split view alone, in iPad works; in iPhone shows only detail view. but if you put the split view inside a Tab Bar (as I need it) both in iPad and iPhone shows only Detail View. How can I fix this problem?	https://forums.raywenderlich.com/t/uisplitviewcontroler-dont-show-master-view/166372	CC-MAIN-2022-27	refinedweb	156	56.76
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.2) Gecko/20100115 Firefox/3.6 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.2) Gecko/20100115 Firefox/3.6 With the new FF 3.6 Final i get a crash on Firefox, if i browse to adress www. golem.de. On previous FF Version 3.5 i never had a problem with this. I identify the addon Stylish and a specific userstyle for the website. In this code i found that the last code block /** * Remove ad at the top of the menu * (maybe to specific) / td.headerbg div, td.headerbg h5[style="text-transform: none; text-align: center; background-color: rgb(184, 23, 26);"] { display: none !important; } the malfactor for the FF crash. If i delete this code block i get no crash. Here is the complete userstyle: @namespace url(); @-moz-document domain("golem.de") { /* * User style for geman language news site. * * * * Feel free to make suggestions and report bugs. / /* * Full width for homepage, articles and forum / table[width="972"] { width: 100% !important; } /* * Full width for screenshot overviews / table[width="932"] { width: 100% !important; } /* * Full width for tables with subheaders / table[width="480"] { width: 100% !important; } /* * Reduce page height to visible content / td.leftedge img { height: 100% !important; } /* * Left alignment for newsletter input field / td.headerbg form table[align="right"] { align: left !important; } /* * Fixed width for right column in forum pages * * Thanks to DreadKing and ChoGGi! * () / table[width="972"]>tbody>tr>td[valign="top"][rowspan="3"] { width:280px!important } /* * Remove header ad / #big { display: none !important } /* * Remove skyscraper ad / table td[rowspan="5"] { width: 0 !important; } /* * Remove skyscraper ad / table td[rowspan="5"] #sky { display: none !important; } /* * Remove ad in the article / #contentad { display: none !important; } /* * Remove ad in the article / #contentad2 { display: none !important; } /* * Remove footer ad / div[style="margin-top: 10px; clear: both;"] { display: none !important } /* * Remove ad at the top of the menu * (maybe to specific) / td.headerbg div, td.headerbg h5[style="text-transform: none; text-align: center; background-color: rgb(184, 23, 26);"] { display: none !important; } } Reproducible: Always Steps to Reproduce: 1. Install addon stylish() on FF 3.6 2. Install userstyle and activate the userstyle 3. browse to 4. FF crash Actual Results: FF crash Expected Results: FF get a error or works fine as FF 3.5, but no crash. FF should not crash You should report this to the author of stylish (In reply to comment #1) > You should report this to the author of stylish Yes, i report it to author, but i think it's a FF Bug. > (In reply to comment #1) > > You should report this to the author of stylish > > Yes, i report it to author, but i think it's a FF Bug. What method is the add on calling when it crashes? What arguments is it passing? The add on author can tell us and raise a bug if required with sufficient information that we may be able to fix it. Easily reproduced using a new profile in Firefox 3.6 on Linux with given STR. Not invalid; confirming. bp-c1bd0007-27f9-470e-ab18-1e2c32100122 0 libxul.so nsTextControlFrame::SetInitialChildList layout/generic/nsQueryFrame.h:278 1 libxul.so nsCSSFrameConstructor::ConstructFrameFromItemInternal layout/base/nsCSSFrameConstructor.cpp:4069 2 libxul.so nsCSSFrameConstructor::ConstructFramesFromItem layout/base/nsCSSFrameConstructor.cpp:5644 3 libxul.so nsCSSFrameConstructor::ConstructFramesFromItemList layout/base/nsCSSFrameConstructor.cpp:9609 4 libxul.so nsCSSFrameConstructor::ProcessChildren layout/base/nsCSSFrameConstructor.cpp:9717 5 libxul.so nsCSSFrameConstructor::ConstructTableCell layout/base/nsCSSFrameConstructor.cpp:2363 ... ... For future reference for crashes, post crash IDs: The crashing user style can be further reduced to simply: @namespace url(); @-moz-document domain("golem.de") { td.headerbg div { display: none; } } Created attachment 455884 [details] testcase (uses enhanced privileges) This is also crashing trunk builds. I have also a case with a similar testcase, that crashes on print preview. It seems bad to me that Stylish is also modifying anonymous content. I don't think that is something they want. But perhaps there is no better way of doing this? It is well known issue Yeah, I can vaguely remember some discussion about that (on bugzilla?). Anyway, shouldn't there be an API there that does the same as AGENT_SHEET, but doesn't count for native anonymous elements? Don't see how adding an API can block a branch release, especially when it's not even assigned to someone to fix on trunk. Me neither, but I don't see a blocking1.9.3? flag. Gecko 1.9.3 became 2.0 => the flag is blocking2.0 now Confusing, I thought that flag was for fennec2.0. Fennec is handled in the blocking-fennec flag. Gecko blocking flag info: Yes, I know now, but it is still confusing. Especially since the 2.0 flag is just under the fennec1.1 flag. It seems like the fennec1.1 flag has now changed into the fennec flag. Stylish should be using USER_SHEET -- that's what it's for. I agree that this is a bug in Stylish, so minusing on that basis. The crash is gone, if i use my Firefox4 beta4, no crash here. The browser crashes. when the following CSS is added into stylish 1.0.x. Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0b5pre) Gecko/20100824 Minefield/4.0b5pre ID:20100824040950 @namespace url(); div {overflow:visible !important;} This CSS hits . (In reply to comment #6) > I have also a case with a similar testcase, that crashes on print preview. After minimizing that testcase, I got a different stacktrace, so I filed a new bug for it, bug 590302. Jorge, could we get Stylish to stop creating UA sheets with broken styling in them? UA sheets are allowed to violate various layout invariants (not least because we use UA sheets to implement them to start with), so can easily cause crashes or other sorts of bad behavior. Adding Jason Barnabe, since I believe he can answer this better. Stylish is like Greasemonkey, in that it will run user-generated styles, some of which may be problematic. It's probably very difficult to implement a filter for these broken styles, but I'm interested in the suggestion given in comment #16, and would like to know why it isn't used in current versions of Stylish. Stylish used USER_SHEET until bug 369676 went in (see also bug 424184), at which time I switched it to AGENT_SHEET. There were and still are a number of styles on userstyles.org which changed how scrollbars work, and not making the switch would have made those styles non-functional. It's a known issue (by me, at least) that you can cause crashes with Stylish if your selectors match anonymous content and you change certain properties (especially "overflow"). It's also been made clear to me that the crashes caused by such styles will not be fixed by the Mozilla devs (see bug 491067). It's a trade-off I've accepted. It's not "will not" but "cannot, without introducing yet another level of even more privileged stylesheets". Except we'd have to restrict scrollbar styling to _that_ level, then, and then Stylish would switch to using that level or something. Maybe what we should do is just disallow extensions adding UA-level sheets and be done with it. :( Well, I'm the submitter of bug 925984. Before making any hasty decisions and/or assumptions, can you guys please check out the gdb backtrace (using a Firefox DEBUG build with symbols) which I provided? Maybe it will give more insight... After some more testing, it's evident that Jason and Martijn are actually hitting spot-on here. In my case it was #something DIV {...} in CSS. It's indeed anonymous elements, in particular _anonymous DIVs_ that provoke this. Once you assign the DIV a class name, this madness stops. However, for user styles, it must be noted that we're doomed to what the website author* has specified: whenever they chose to use an _anonymous_ div instead of a <"div, we cannot just invent an artificial temp class name just to prevent this crash. In fact we "user-stylers" will either have to count on the site author's goodwill so that he/she will make their site "Stylish-compatible". If not, the only (very ugly) way out will be via a parent element that _does_ have a proper DOM ID. Andreas, I did look at your stack. The point is that your style rearranges the insides of text inputs in a way they don't expect, causing them to crash. This has nothing to do with the website author and everything to do with the fact that Stylish purposefully applies your styles to layout implementation details like the insides of scrollbars and the insides of text inputs. Once you do that, if you use the wrong style all bets are off. Jason, could Stylish have two buckets of stylesheets: ones meant to style scrollbars and ones not trying to do it? And then only use AGENT_SHEET for the former? Boris, thanks for taking a look into it. But the main problem I see is that there is no guideline what we may do and what we may not do. Nowhere. When applying a custom style to a web site, how should we know where to keep our fingers off (i. e. what _are_ the actual invariants?) and where it's safe to mess around? It's on you guys to know how the CSS parser internals work - _we_ can't do but some arbitrary guesswork. Andreas, I think you may be misunderstanding the concept of anonymous content. An "anonymous div" is not merely a div with no ID or class attribute, but rather it's part of Firefox's internal representation of an element. For example, if you use <input type="file">, Firefox internally translates this to a label, a text input, and a button. This is the anonymous content. When you use "#something div" as a selector in this case, you're actually matching part of this anonymous content, and if you change it ways that Firefox doesn't expect, it can cause crashes. There are sometimes ways to change your selectors so they don't match the anonymous content. For example, if all the divs you want to affect are direct children of #something, you could use "#something > div" instead. Alternately, as you mention, if there are IDs, classes, or attributes on these divs, you could select on that.. I don't see this as a bug in Stylish. Given that Mozilla doesn't want to guard against these kinds of crashes (a decision I accept), I see it as conscious decision on my part to accept the possibility of crashes in exchange for the possibility of styling the internals, like scrollbars. There are a myriad of other ways you can seriously bork Firefox with Stylish without crashing it, anyway. >There are sometimes ways to change your selectors so they don't match the anonymous content. For >example, if all the divs you want to affect are direct children of #something, you could use >"#something > div" instead. Ah, thanks Jason!! That "fixed" the crash. So it must been some greater ambiguity I created, i. e. the engine didn't know what decision to take. BTW, my actual style is 500+ lines, but I'm against posting pagesfuls of style code, which is considered 'rude' here. Again, in a nutshell; #something DIV { ... } ---> CRASH #something > DIV { ... } ---> NO CRASH Great! (In reply to Jason Barnabe (np) from comment #30) >. Would it be possible to move to a system where userstyle developers have to opt-in to the AGENT_SHEET behavior? This would break some of the current userstyles, but that could be minimized by notifying developers about the change and making a slow transition. That's definitely a possibility. I'd prefer the switch to AGENT_SHEET to be automatic based on the code content if possible, because it reduces the requirements on style authors' part. Many of them only have basic CSS knowledge (they may simply be flipping colors around on an existing style) and English proficiency. You'd end up with styles that should flip the switch not flipping it and vice versa. > I will do some investigation of styles posted on userstyles.org to see if there's any > code patterns that indicate a scrollbar style (or other intentionally > anonymous-content-affecting style) That would be awesome. Thank you! Stylish 1.4.1b1 now uses AUTHOR by default, so giving it this code no longer crashes: div {overflow:visible !important;} Authors can opt-in to AGENT with the magic comment /* AGENT_SHEET */, with the potential crashiness that entails. Styles posted on userstyles.org that appear to be for scrollbars have had this added automatically. Jason, thank you for doing that! I second that! Thanks for your hard work on that not-too-trivial issue. Stylish 1.4.1 is now available on AMO.	https://bugzilla.mozilla.org/show_bug.cgi?id=541506	CC-MAIN-2017-26	refinedweb	2,174	68.06
Bug #16448 art should throw if Assns<A,B> is declared but Assns<B,A> is put Description An issue recently arose in MicroBooNE where the following was declared in the producer's c'tor: produces<Assns<recob::Track,recob::Vertex>>(); but an Assns<recob::Vertex,recob::Track> product was placed onto the event. This can cause problems for looking up the Assns product later in the same job. Resolving this issue is not trivial--it requires understanding how the friendlyClassName of an Assns product is created and, consequently, how that should affect the product-checking done during the Event::commit stage. History #1 Updated by Kyle Knoepfel over 3 years ago - Status changed from New to Accepted After discussion, there may be some inconsistencies with how the friendly class names are formed. Even if those inconsistencies are resolved, significant backwards compatibility issues arise. We will, therefore, discuss this at a later time. #2 Updated by Kyle Knoepfel over 3 years ago Inconsistencies in creating the friendly class name have been resolved with commit canvas:22a96e7. The issue was that for testing, the classes A and B were defined in an anonymous namespace. The friendly name of each class is therefore (anonymous namespace)::A. When that pattern is presented to the regex parser, the open parenthesis indicates the beginning of a group. The solution is to escape all parentheses. In practice, this is unlikely to have been a problem because the context in which friendlyClassName() is called does not involve classes defined in an anonymous namespace. However, this inconsistency has at least been resolved. If this ever becomes necessary, the (e.g.) (anonymous namespace):: prefix will need to be replaced with something suitable for a ROOT file branch name. The problem of detecting when an Assns<B,A> is placed onto the event instead of an Assns<A,B> has yet to be solved. #3 Updated by Kyle Knoepfel over 3 years ago - Category set to Infrastructure - Status changed from Accepted to Resolved - Assignee set to Kyle Knoepfel - Target version set to 1209 - % Done changed from 0 to 100 - SSI Package art added The solution was to replace BranchID-based product checking with TypeLabel-based checking. Unfortunately, a TypeLabel is larger in size than a BranchID, but it was partially mitigated by removing the BranchType member from the TypeLabel. It is now an error for an Assns product with reversed template parameters (with respect to the produces<> call) to be placed onto an event. With this commit, the following error is also detected: MyProducer::MyProducer(Parameters const&) { produces<A,B>() produces<B,A>() } In this circumstance, an exception will be thrown that looks like: cet::exception caught in art ---- LogicError BEGIN check_for_duplicate_Assns: An attempt has been made to call the equivalent of produces<art::Assns<B,A,void>>("") which results in a prepared ("friendly") name of: ABvoidart::Assns That friendly name has already been registered for this module. Please check to make sure that produces<> has not already been called for an Assns<> with reversed template arguments. Such behavior is not supported. Contact artists@fnal.gov for guidance. ---- LogicError END Implemented with commit art:801c3bc9. #4 Updated by Kyle Knoepfel over 3 years ago - Target version changed from 1209 to 2.07.01 #5 Updated by Kyle Knoepfel over 3 years ago - Status changed from Resolved to Closed Also available in: Atom PDF	https://cdcvs.fnal.gov/redmine/issues/16448	CC-MAIN-2021-04	refinedweb	563	51.28
Hi Ralf， On Thu, Jun 23, 2011 at 1:52 AM, Ralf Wildenhues <address@hidden> wrote: > Hi Mike, > > * Mike Frysinger wrote on Thu, Jun 23, 2011 at 02:08:50AM CEST: >> >> [quote] >> Note that Automake does not make any distinction between rules with >> commands and rules that only specify dependencies. So it is not >> possible >> to append new dependencies to an automake-defined target without >> redefining the entire rule. >> [/quote] >> >> i happened to notice though that automake only parses exact semantic matches. >> it cannot handle going through variables. so i tried out: >> $(libbsdl_la_OBJECTS): bsdl_bison.h vhdl_bison.h > >> is this an undocumented feature ? or a bug that'll get fixed at some point ? >> we've been using this for a few years now without problems, but past behavior >> does not guarantee future behavior ... > > I'd say there are two undocumented bits involved here: the name of the > _OBJECTS variable, and the fact that automake only parses exact matches. > Both are exploited in several user packages, esp. the latter one is, > because in many cases there is no better way. > > I'd say that for any of those to change, it would require at least a > major version bump, a big announcement, and most importantly, a > documented replacement mechanism that works for all use cases. And > maybe even an upgrade path that warns users about their current code. > I don't see that happening anytime soon. The replacement mechanism > would obviously have to be the first thing, to allow smooth migration. > > The only thing that keeps me from setting current behavior in stone is > that it is sooo unintuitive and ugly. > There is another ugly way to achieve the same purpose, i.e. redefine the entire, like this: vhdl_flex.lo: vhdl_flex.c vhdl_bison.h if am__fastdepCC $(AM_V_CC)$(LTCOMPILE) -Wno-error -MT $@ -MD -MP -MF $(DEPDIR)/$.Tpo -c -o $@ `test -f '$<' \|\| echo '$(srcdir)/'`$< $(AM_V_at)$(am__mv) $(DEPDIR)/$.Tpo $(DEPDIR)/$*.Plo else $(AM_V_CC) @AM_BACKSLASH@ if AMDEP source='$<' object='$@' libtool=yes @AMDEPBACKSLASH@ DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@ endif $(LTCOMPILE) -Wno-error -c -o $@ `test -f '$<' \|\| echo '$(srcdir)/'`$< endif This way also references several undocumented internal variables of Automake. Which way is preferred? or less ugly? The root cause of this issue is that Automake does not distinguish rules with commands and rules that only specify dependencies. I'm curious that why Automake does not distinguish them. Is it too difficult to implement or it is also a feature or just because no one does it? Regards, Jie	http://lists.gnu.org/archive/html/automake/2011-06/msg00032.html	CC-MAIN-2015-27	refinedweb	411	64.91
Networked multiplayer tic-tac-toe Casual games are extremely popular and very lucrative, and it's easy to see why. Not everyone across all the age groups is interested in playing online, first-person shooters against hordes of preteens with lightening-speed reflexes. Sometimes, it's more interesting to play games where you have time to think and strategize or where the goal is to cooperate with each other to win the game. The great thing about casual games from the developers' perspective is that they are much easier to build than the graphics-intensive, first-person shooters or sports games. So it's easier for a single developer, or a group of developers, to produce a first version of a novel new game. In this article, we go through the basics of creating a casual, networked multiplayer tic-tac-toe game. The game server is a MySQL- and PHP-based web application with an XML interface. The front end is a native Android application that works on Android phones. Building the back end The back end starts with a simple MySQL database that has two tables. Listing 1 shows the schema for the database. Listing 1. db.sql DROP TABLE IF EXISTS games; CREATE TABLE games( id INT NOT NULL AUTO_INCREMENT, primary key ( id ) ); DROP TABLE IF EXISTS moves; CREATE TABLE moves( id INT NOT NULL AUTO_INCREMENT, game INT NOT NULL, x INT NOT NULL, y INT NOT NULL, color INT NOT NULL, primary key ( id ) ); The first of the two tables is the games table, which has just the unique ID of the game. In a production application, you likely have a users table, and the games table includes the user IDs of both players. To keep it simple, though, I forgo this approach to concentrate on the basics of storing the game data, communicating between the client and server, and building the front end. The second table is the moves table, which includes the individual moves for the given game, so it has five columns. The first column is the unique ID of the move. The second column is the ID of the game this move applies to. Then come the x and y positions of the move. These values should be between 0 and 2 for both x and y given that you have a three-by-three grid. The last field is the "color" of the move, which is an integer that indicates X or O. To build the database, first use mysqladmin to create it and then use the mysql command to run the db.sql script as shown here: % mysqladmin --user=root --password=foo create ttt % mysql --user=root --password=foo ttt < db.sql This step creates a new database called "ttt," which has the tic-tac-toe schema. Now that you have the schema, you need to create a way to start a game. For this, you have a script called start.php, as in Listing 2. Listing 2. start.php <?php header( 'Content-Type:text/xml' ); $dd = new PDO('mysql:host=localhost;dbname=ttt', 'root', ''); $sql = 'INSERT INTO games VALUES ( 0 )'; $sth = $dd->prepare($sql); $sth->execute( array() ); $qid = $dd->lastInsertId(); $doc = new DOMDocument(); $r = $doc->createElement( "game" ); $r->setAttribute( 'id', $qid ); $doc->appendChild( $r ); print $doc->saveXML(); ?> The script starts by connecting to the database. It then executes an INSERT statement against the games table and gets back the ID that was generated. From there it creates an XML document, adds the ID to a game tag, and exports the XML. You need to run this script to get a game in the database because the simple Android application does not have an interface to create games. Here is the code: $ php start.php <?xml version="1.0"?> <game id="1"/> $ Now you have your first game. To see the list of games, use the games.php script that is in Listing 3. Listing 3. games.php <?php header( 'Content-Type:text/xml' ); $dbh = new PDO('mysql:host=localhost;dbname=ttt', 'root', ''); $sql = 'SELECT * FROM games'; $q = $dbh->prepare( $sql ); $q->execute( array() ); $doc = new DOMDocument(); $r = $doc->createElement( "games" ); $doc->appendChild( $r ); foreach ( $q->fetchAll() as $row) { $e = $doc->createElement( "game" ); $e->setAttribute( 'id', $row['id'] ); $r->appendChild( $e ); } print $doc->saveXML(); ?> This script, like the start.php script, starts by connecting to the database. After that it queries the games table to see what's available. And from there it creates a new XML document, adds a games tag, then adds game tags for each of the available games. When you run this script from the command line, you see something like this: $ php games.php <?xml version="1.0"?> <games><game id="1"/></games> $ You can also run this script from the web browser to see the same output. Excellent! With the games API out of the way, it's time to write the server code to handle the moves. This code starts with building a helper script called show_moves that gets the current moves for a given game and exports them as XML. Listing 4 shows the PHP code for this helper function. Listing 4. show_moves.php <?php function show_moves( $dbh, $game ) { $sql = 'SELECT * FROM moves WHERE game=?'; $q = $dbh->prepare( $sql ); $q->execute( array( $game ) ); $doc = new DOMDocument(); $r = $doc->createElement( "moves" ); $doc->appendChild( $r ); foreach ( $q->fetchAll() as $row) { $e = $doc->createElement( "move" ); $e->setAttribute( 'x', $row['x'] ); $e->setAttribute( 'y', $row['y'] ); $e->setAttribute( 'color', $row['color'] ); $r->appendChild( $e ); } print $doc->saveXML(); } ?> The script takes a database handle and the game ID. From there it executes the SQL to get the list of moves. Then it creates an XML document with the moves for the given game. You created this helper function because there are two scripts that use it; the first is a moves.php script that returns the current moves for the specified game. Listing 5 shows this script. Listing 5. moves.php <?php require_once( 'show_moves.php' ); header( 'Content-Type:text/xml' ); $dbh = new PDO('mysql:host=localhost;dbname=ttt', 'root', ''); show_moves( $dbh, $_REQUEST['game'] ); ?> This simple script includes the helper function code, connects to the database, and then invokes the show_moves function with the specified game ID. To test this code, use the curl command to invoke the script on the server from the command line: $ curl "" <?xml version="1.0"?> <moves/> $ Sadly, you haven't made any moves yet, so it's not a particularly interesting output. To remedy that you need to add the final script to the server API. Listing 6 shows the move.php script. Listing 6. move.php <?php require_once( 'show_moves.php' ); header( 'Content-Type:text/xml' ); $dbh = new PDO('mysql:host=localhost;dbname=ttt', 'root', ''); $sql = 'DELETE FROM moves WHERE game=? AND x=? AND y=?'; $sth = $dbh->prepare($sql); $sth->execute( array( $_REQUEST['game'], $_REQUEST['x'], $_REQUEST['y'] ) ); $sql = 'INSERT INTO moves VALUES ( 0, ?, ?, ?, ? )'; $sth = $dbh->prepare($sql); $sth->execute( array( $_REQUEST['game'], $_REQUEST['x'], $_REQUEST['y'], $_REQUEST['color'] ) ); show_moves( $dbh, $_REQUEST['game'] ); ?> This script starts by including the helper function and connecting to the database. It then executes two SQL statements. The first removes any move that might collide with the one being sent in. The second inserts a new row into the moves table for the specified move. The script then returns the list of moves to the client. This step saves the client from having to make two requests each time it makes a move. Bandwidth isn't cheap, so any time you can conglomerate requests you should. To test that this all works you can make a move: $ curl "" <?xml version="1.0"?> <moves><move x="1" y="2" color="1"/></moves> With the game server code complete, you can build the Android front end to this multiplayer networked game. Building the Android front end First, install the Android SDK, as well as some Android platform versions, and then finally Eclipse and the Android Eclipse plug-in. Thankfully, all this is well documented on the Android site (see Resources for links). In-depth coverage of how to set up your development environment would take up this whole article and more. After you set up the development environment, launch Eclipse and start a new Android project. You should see something similar to Figure 1. Figure 1. Creating the Android application in Eclipse Figure 1 shows the project wizard for Android applications. Enter a project name, select the Create new project in workspace radio button and specify the location for code with the UI elements. In the Build Target checklist, select an Android platform. For this code, I use Android 2.3.1. The code is pretty simple so you can use any version that you prefer. If you don't see any platforms listed, then you need to download and install the platforms as noted in the Android SDK setup instructions. Be warned that downloading all of these platforms takes a long, long time. In the Properties section, fill in the application name and the package name. I used "Tic Tac Toe" and "com.jherrington.tictactoe" in the respective fields. Then, select the Create Activity check box and enter a name for the activity. I used "TicTacToeActivity" as the activity name. Click Finish to see a new project that resembles Figure 2. Figure 2. The TicTacToe project files Figure 2 shows the top-level directories and files for an Android application (the directories are src, gen, Android 2.3.1, and res and the files are assets, AndroidManifest.xml, default.properties, and proguard.cfg). The important items are: - The res directory, which contains resources - The src directory, which has the Java™ source - The manifest file, which contains the biographical information about the application Your first edit is to the manifest file. Most of the file is already correct, but you need to add the Internet permission so the application can make requests over the Internet. Listing 7 shows the completed manifest file. Listing 7. AndroidManifest.xml <?xml version="1.0" encoding="utf-8"?> <manifest xmlns: <uses-permission android: <uses-sdk android: <application android: <activity android: <intent-filter> <action android: <category android: </intent-filter> </activity> </application> </manifest> The only change was to add the uses-permission tag at the top of the file. Your next task is to design the UI. For this, tweak the layout.xml file, which is contained in the res/layout directory. Listing 8 shows the new contents for this file. Listing 8. layout.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns: <LinearLayout android: <Button android:</Button> <Button android:</Button> </LinearLayout> <com.jherrington.tictactoe.BoardView android:</com.jherrington.tictactoe.BoardView> </LinearLayout> This is a straightforward layout. At the top is a set of two buttons wrapped in a linear layout with a horizontal orientation. These two buttons are the X and O buttons that the user uses to specify which color he or she is playing. The rest of the code is filled with a BoardView class, which shows the Tic Tac Toe board with the current game. The code for the BoardView class is in Listing 11. With the layout in hand, it's time to write some Java code for the application. This coding starts with the TicTacToeActivity class in Listing 9. Activities are the basic building blocks of Android applications. Each application has one or more activities that represent the various states of the application. As you navigate through the application you build a stack of activities that you can then pop out of by using the back button on the phone. The TicTacToe application has just a single activity. Listing 9. TicTacToeActivity.java package com.jherrington.tictactoe; import java.util.Timer; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.view.ViewGroup.LayoutParams; import android.widget.Button; import android.widget.Gallery; import android.widget.LinearLayout; public class TicTacToeActivity extends Activity implements OnClickListener { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button playx = (Button)this.findViewById(R.id.playx); playx.setOnClickListener( this ); Button playo = (Button)this.findViewById(R.id.playo); playo.setOnClickListener( this ); Timer timer = new Timer(); UpdateTimer ut = new UpdateTimer(); ut.boardView = (BoardView)this.findViewById(R.id.bview); timer.schedule( ut, 200, 200 ); } public void onClick(View v) { BoardView board = (BoardView)this.findViewById(R.id.bview); if ( v.getId() == R.id.playx ) { board.setColor( 2 ); } if ( v.getId() == R.id.playo ) { board.setColor( 1 ); } } } The activity has two methods. The first is the onCreate method, which builds the user interface, connects the onClick handler to the X and O buttons, and starts the update timer. The update timer is used to refresh the state of the game every 200 milliseconds. This feature allows both players to see when the other player moves. The onClick handler sets the current color of the board based on whether the user clicks the X or O button. The GameService class, in Listing 10, is a singleton class that represents the game server and the current state of the given game. Listing 10. GameService.java package com.jherrington.tictactoe; import java.util.ArrayList; import java.util.List; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory;.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import android.util.Log; public class GameService { private static GameService _instance = new GameService(); public int[][] positions = new int[][] { { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } }; public static GameService getInstance() { return _instance; } private void updatePositions( Document doc ) { for( int x = 0; x < 3; x++ ) { for( int y = 0; y < 3; y++ ) { positions[x][y] = 0; } } doc.getDocumentElement().normalize(); NodeList items = doc.getElementsByTagName("move"); for (int i=0;i<items.getLength();i++){ Element me = (Element)items.item(i); int x = Integer.parseInt( me.getAttribute("x") ); int y = Integer.parseInt( me.getAttribute("y") ); int color = Integer.parseInt( me.getAttribute("color") ); positions[x][y] = color; } } public void startGame( int game ) { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost(""); try { List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2); nameValuePairs.add(new BasicNameValuePair("game", Integer.toString(game)));()); } } public void setPosition( int game, int x, int y, int color ) { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost(""); positions[x][y] = color; try { List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2); nameValuePairs.add(new BasicNameValuePair("game", Integer.toString(game))); nameValuePairs.add(new BasicNameValuePair("x", Integer.toString(x))); nameValuePairs.add(new BasicNameValuePair("y", Integer.toString(y))); nameValuePairs.add(new BasicNameValuePair("color", Integer.toString(color)));()); } } } This code is some of the most interesting code in the application. First, you have the updatePositions method, which takes the XML returned from the server and looks for the move elements, then updates the positions array with the current set of moves. The positions array has a value for each position on the board; zero indicates an empty space, 1 represents "O," and 2 is for "X." The other two functions, startGame and setPosition, are how you communicate with the server. The startGame method requests the current set of moves from the server and updates the list of positions. The setPosition method posts the move to the server by creating an HTTP post request and setting up the data for the post using an array of name-value pairs, which are then encoded for transport. It then parses the response XML to update the list of positions. If you look closely, the IP used to connect to the server is really interesting. It's not "localhost" or "127.0.0.1"; it's "10.0.2.2," which is an alias for the machine that the emulator is running on. Because the Android phone is itself a UNIX® system, it has its own services on localhost. Fascinating, right? It's not often that it's so clear that the phone is not really a phone per se, but a fully fledged computer that fits in your palm and just happens to have a phone built into it. So, where are we? You have the activity, which is the main component for the application; you have the UI layout set up; you have the Java code to connect to the server. Now you need to draw the game board. which is done by the BoardView class in Listing 11. Listing 11. BoardView.java package com.jherrington.tictactoe; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; public class BoardView extends View { private int _color = 1; public void setColor( int c ) { _color = c; } public BoardView(Context context) { super(context); GameService.getInstance().startGame(0); } public BoardView(Context context, AttributeSet attrs) { super(context,attrs); GameService.getInstance().startGame(0); } public BoardView(Context context, AttributeSet attrs, int defStyle) { super(context,attrs,defStyle); GameService.getInstance().startGame(0); } public boolean onTouchEvent( MotionEvent event ) { if ( event.getAction() != MotionEvent.ACTION_UP ) return true; int offsetX = getOffsetX(); int offsetY = getOffsetY(); int lineSize = getLineSize(); for( int x = 0; x < 3; x++ ) { for( int y = 0; y < 3; y++ ) { Rect r = new Rect( ( offsetX + ( x * lineSize ) ), ( offsetY + ( y * lineSize ) ), ( ( offsetX + ( x * lineSize ) ) + lineSize ), ( ( offsetY + ( y * lineSize ) ) + lineSize ) ); if ( r.contains( (int)event.getX(), (int)event.getY() ) ) { GameService.getInstance().setPosition(0, x, y, _color); invalidate(); return true; } } } return true; } private int getSize() { return (int) ( (float) ( ( getWidth() < getHeight() ) ? getWidth() : getHeight() ) * 0.8 ); } private int getOffsetX() { return ( getWidth() / 2 ) - ( getSize( ) / 2 ); } private int getOffsetY() { return ( getHeight() / 2 ) - ( getSize() / 2 ); } private int getLineSize() { return ( getSize() / 3 ); } protected void onDraw(Canvas canvas) { Paint paint = new Paint(); paint.setAntiAlias(true); paint.setColor(Color.BLACK); canvas.drawRect(0,0,canvas.getWidth(),canvas.getHeight(), paint); int size = getSize(); int offsetX = getOffsetX(); int offsetY = getOffsetY(); int lineSize = getLineSize(); paint.setColor(Color.DKGRAY); paint.setStrokeWidth( 5 ); for( int col = 0; col < 2; col++ ) { int cx = offsetX + ( ( col + 1 ) * lineSize ); canvas.drawLine(cx, offsetY, cx, offsetY + size, paint); } for( int row = 0; row < 2; row++ ) { int cy = offsetY + ( ( row + 1 ) * lineSize ); canvas.drawLine(offsetX, cy, offsetX + size, cy, paint); } int inset = (int) ( (float)lineSize * 0.1 ); paint.setColor(Color.WHITE); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth( 10 ); for( int x = 0; x < 3; x++ ) { for( int y = 0; y < 3; y++ ) { Rect r = new Rect( ( offsetX + ( x * lineSize ) ) + inset, ( offsetY + ( y * lineSize ) ) + inset, ( ( offsetX + ( x * lineSize ) ) + lineSize ) - inset, ( ( offsetY + ( y * lineSize ) ) + lineSize ) - inset ); if ( GameService.getInstance().positions[ x ][ y ] == 1 ) { canvas.drawCircle( ( r.right + r.left ) / 2, ( r.bottom + r.top ) / 2, ( r.right - r.left ) / 2, paint); } if ( GameService.getInstance().positions[ x ][ y ] == 2 ) { canvas.drawLine( r.left, r.top, r.right, r.bottom, paint); canvas.drawLine( r.left, r.bottom, r.right, r.top, paint); } } } } } Most of the work here is done in the onTouch method, which responds to the user touching a particular cell on the game board, and the onDraw method, which paints the game board using Android's painting mechanism. The onTouch method uses the sizing functions to figure out a rectangle for each cell position. It then uses the contains method on the rectangle to see if the user clicked within the cell. If they did, it fires off a request to the game service to make the move. The onDraw function uses the sizing functions to both draw the lines of the board and draw any played Xs and Os. The GameServer singleton is used for its positions array, which has the current state of each square on the game board. The last class you need is the UpdateTimer, which uses the game service to update the board positions with their latest values. Listing 12 shows the code for the timer. Listing 12. UpdateTimer.java package com.jherrington.tictactoe; import java.util.TimerTask; public class UpdateTimer extends TimerTask { public BoardView boardView; @Override public void run() { GameService.getInstance().startGame( 0 ); boardView.post(new Runnable(){ public void run(){ boardView.invalidate(); } }); } } The timer is initialized by the TicTacToeActivity class when the application starts up. This timer is a polling mechanism. This is not the most efficient way to communicate between the client and server, but it is the simplest and most reliable. The most efficient way is to use the 1.1 version of the HTTP protocol to hold the connection open and to have the server send out updates to the client when moves are made. This approach is a lot more complex; it requires both the client and the server to support the 1.1 protocol, and it has scalability issues with the number of connections. That approach is outside the scope of this article. For simple demonstration games like this, a polling mechanism works just fine. With the code done, you can test the application. That means starting up the emulator. You should see something like Figure 3 after startup. Figure 3. Launching the Android emulator This is the emulator loading up a fantastic "A N D R O I D" interface, After it's loaded, you see the power-on screen in Figure 4. Figure 4. The emulator launched and ready to go To get into the phone, slide the lock icon to the right. That action gets you to the home screen and generally launches the application that you are debugging. In this case, this action displays the game screen in Figure 5. Figure 5. The game before moves have been made Depending on the state of your server, you either see or do not see any moves. In this case, the game was empty. The Play X and Play O buttons are at the top with the tic-tac-toe game board in the middle of the display. Next, click Play X, then click the center square to see something like Figure 6. Figure 6. X takes center square, of course Figure 6 shows the display of the game board with an X now populating the center square. To verify that the server was connected, you can execute the curl command against the moves.php script on the server to get the most recent list of game moves. To test that the Os work, click Play O and select a corner square as in Figure 7. Figure 7. O takes a corner square You can play both Xs and Os. The application connects to the server to hold the state of the game in a shared location. And because of the update timer, each user can see the moves made by the other. Conclusion Is this a complete game? Not really. There is no victory condition check, players can overwrite positions, and there is no turn check. But the basic technology pieces are present: a game server with shared stored state between the players and a native graphical application on a mobile device that connects to the game server to provide an interface to the game. You can use this game as a starting point for your own game and build it out however you please. Just remember to keep it casual and fun, and you might have yourself the next Words With Friends or multiplayer Angry Birds. Resources Learn - Eclipse: Learn more about the IDE used in this article to develop the Android application. Find Eclipse downloads and plugins, too. - PHP Development Tools for Eclipse: Need an IDE for PHP? The Eclipse project has an extension for that plus other Eclipse plugins for just about everything. - Android Market: After you write your Android networked multiplayer casual game, upload it to the Android marketplace. And let us know that you have done so in the comments section of this article. - The PHP site: Explore the best reference for PHP that's available. - The W3C: Visit a great site for standards, in particular the XML standard is relevant to this article. - Android Developer site: Download the SDK and the Eclipse plug.	http://www.ibm.com/developerworks/library/x-androidtictactoe/	CC-MAIN-2014-35	refinedweb	3,964	57.57
Who said you will return in World War 2? "I will return" was a quote from General Douglas MacArthur Who said I will return in World War 2? Douglas MacArthur General of World War 2 who said i shall return? Douglas McArthur. Who said I shall return? General Douglas MacArthur from World War 2, what speech & to who Who was the general during World War 2 that said 'We shall return'? General Douglas MacArthur. Why did troops return in world war 2? Troops went home when the war ended. Why did the US support the return of the French at the end of World War 2? The US simply defeated an enemy, and tried to allow the world to return to the way it was before the war. Which president promised a return to normalcy after world war 2? A "return to normalcy" was coined by presidential candidate Warren Harding. He promised that the United States would return to the way of life before World War I. Did the kids return home after the blitz in World War 2? Yes they did Did Gen Douglas win a medal of honor for World War 2? If you mean General Douglas Mac Arthur, he did win a Medal of Honor for service in the Pacific in World War II. My father, who served in the Philippines said, "Remember when Mac Arthur said 'I shall return' when he left the Philippines? It was me he was supposed to come back for". What were Australian soldiers given upon their return from World War 2? they were given How many women died in World War 2? People Said over 60,000,000 People Died in World war 2. Why did the Japanese leave Manchuria after World War 2? When a country loses a war, they must return everything they had taken. What town in the US had the least amount of soldiers return after World War 2? It is likely that several small towns sent no recruits to war. Therefore none would return What does POW stand for in world war 2? Prisoner of war, usually said as POW camp. How many soldiers were sent to the war by Canada in ww2? During World War 2, it is said that 1.1 Million Canadians were deployed during World War 2. After world war 2 did the Jews return to Germany? Very, very few returned. When did children return home from the countryside in world war 2? They returned home in stages. There was no official set date for them to return back to cities. Will Call of Duty return to World War 2? Yes the Call of Duty World at War returns to World War II and Call of Duty Black Op is set during the cold war What did Germany offer Mexico in return for fighting in world war 2? Parts of the US they lost in Mexican-American war 1848 What was general Douglas MacArthur famous quote in World War 2? I shall return (to the Phillipines) Why didnt the US return to our former policy of isolationism World War 2? Fear of communism Why can it be said that World War 2 was a War of Movement? Mobile warfare (Blitzkrieg) as compared to the static trenchlines of WW1 . How did Mussolini influence Italy's decision to enter World War 2? Mussolini told Italy that they can have all the land they want if they fight in world war 2. he said that they would not lose the war. What where G.I. passwords in world war 2? Troops in World War II used the password 'flash'. It was meant to be answered in return with the password 'thunder.' Did they eat ice cream in world war 2? yes they ate ice cream in world war 2 my pap was there and he said German ice cream was the best How did the World War I cause World War 2? Because Germany was in a depression paying for their war debt from world war 1 and when Hitler came to power he tried to get more land then he said What general promised the people of the Philippines he would return during world war 2? General MacArthur How many people have been said to be injured and wounded in World War 2? 50-60 million died in the war. Who announced World war 2 is ended? US President Truman said that the war was over 13 December 1946 . In World War 2 this battle was said to be the turning point on the Eastern front? Battle of Stalingrad Who said join the army during world war 2? Uncle Sam wants you! How many troops did the US lose in World War 2? it is said to be around 425,00 Why it is never said that the Russians won World War 2? They did not win just did not lose. Who made the famous promise I shall return to the people of Philippines during World War 2? General Douglas MacArthur promised to return and he made good his promise. What did Winston churchill say when world war 2 ended? He said We had won the War but not the Peace since a cold war had begun against USSR. Who was forced to abandon the Philippines in world War 2 and made the vow I shall return? General Mc Arthur Did world war 2 have nuclear bombs in it? Yes! It did...... Dangerous....... really I am Serious...... Enough Said..... Did Obama say his step father served in World War 2? No, he said his grandfather served. What islands did the U.S. attack during world war 2? Normandy. Nuff said. Why were eggs so rare in the World War 2 time? because my dick said so ] Does World War 2 justify its cause? Yes, World War 2 does justify its cause. Neville Chamberlain had said to Adolf Hitler that if you invade Poland there will be War. Of course, Hitler ignored this and England's prime minister at the time then declared war. What date where evacuation children retured to their families in World War 2? The official return date of the evacuees was in June 1945. What Were the Immediate causes for war with Japan IN World War 2? japan had attacked pearl harbour president Roosevelt said"we will cause war on japan"by david redmond Who said this quote I shall return? "I Shall Return" came from Douglas MacArthur, General of the US Army, as he retreated from the Phillipines, during WW 2. What was the US point of view of World War 2? US said dont put us in this this is not our problem. Why did Winston Churchill declare World War 2? Because he said that Hitler could't attack Poland Who said the british people did not flag nor fail during world war 2? Winston Churchill. Why were Jews imprissoned in world war 2? because hitler said they were going to take over germany Which US reprsentative said no to the us entering World War 2? Jeannette Rankin - she voted no in both World Wars .	https://www.answers.com/Q/Who_said_you_will_return_in_World_War_2	CC-MAIN-2019-30	refinedweb	1,186	83.46
Why Overriding ToString is a Good Idea We all work on ever increasing complexity these days. As software development evolves, so does the amount of information we have to deal with. This, in turn, leads to ever more complex application structures that we have to deal with, and objects that contain way more than just simple data types. Take, for example, the following. When was the last time you saw something like this in your debugger? Figure 1: Uh, oh. A custom type appeared You have a custom type, but you know nothing about that type, so you have to expand it. Figure 2: Expanding the custom file And, inside of that, you have more objects that you need to expand to see them. Although I agree this is not a major issue for a handful of small objects, what happens when your code base expands to hundreds of large objects, each inheriting from a large number of base classes, and with a great number of properties? Then, stop to consider that if that one object you're looking at is but one in a list of 1000 records you've just gotten back from a database. All of a sudden, the view you expect to see in your debugger becomes more than a little daunting. There Is an Easier Way How many of you know what "ToString" is for? If, like many developers, you only ever really use it for conversion, you might ever have only seen it used in circumstances similar to the following: int myAge = 21; string strMyAge = myAge.ToString(); Did you ever stop to think exactly what "ToString" is, however? ToString is a virtual function that the base .NET object class implements, and because it's implemented in the base object class, it's implemented in every class and/or object that derives from it. In .NET that basically means every int, decimal, float, and myObject that you define has a "ToString" method on it. Now, look back at Figures 1 & 2. See the "{xsltocsv.CustomerInfo}" part, or the "{xsltocsv.Address}" part in those two figures? Well, that's the inherited "ToString" function that produces them for the debugger to display. Because the base class implements this as a virtual function, it's very easy for you to override it and provide your own implementation of "ToString" on your own objects. Why would you want to do this, however? Let's look at an example. The classes in Figures 1 and 2 were created as follows: namespace xlstocsv { public class Address { public string HouseNumber { get; set; } public string Street { get; set; } public string Town { get; set; } public string County { get; set; } public string PostCode { get; set; } } public class CustomerInfo { public int Recordid { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public string Email { get; set; } public Address Address { get; set; } } } If we were to run through the debugger now and inspect them in the locals window, you'd see exactly the same output as Figures 1 & 2. However, if we now add an overridden ToString method, something like the following namespace xlstocsv { public class Address { public string HouseNumber { get; set; } public string Street { get; set; } public string Town { get; set; } public string County { get; set; } public string PostCode { get; set; } public override string ToString() { return string.Format("{0} {1}, {2}, {3}, {4}", HouseNumber, Street, Town, County, PostCode); } } public class CustomerInfo { public int Recordid { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public string Email { get; set; } public Address Address { get; set; } public override string ToString() { return string.Format("{0} {1} <{2}>", FirstName, LastName, Email); } } } we should now find we get an entirely different experience in the debugger. Figure 3: Much improved over the original "custom" line And, even if we do still have to expand objects, as shown in Figure 4: Figure 4: Again, much improvement over the Figure 2 view we don't have to drill down level after level to get a sensible view of the data our objects hold. Of course, this also means that if you then do the following: CustomerInfo myCustomer = new CustomerInfo{ ... } string strCustomerInfo = myCustomer.ToString(); you'll also get that same string assigned to the string representation of your object, which is great for formatting objects for different purposes. If you look in my example above, you can see the output from my customer object could be used directly to create an email address entry in a mail client. So, even if you don't intend to convert your data entities to strings, providing a ToString override can make debugging and developing just that little bit easier and perhaps save you some sanity. Do you have a .NET question that's bugging you? Or, you're just curious about something you read recently and would like to know more? Leave a comment below or ping me on Twitter as @shawty_ds and I'll see what I can do to feature it in a future column. Good articlePosted by Albert on 02/23/2015 06:52pm Hello Peter Shaw, I am a programmer from Taiwan, just read your article, think to override is a good idea, so, may I translate this article into Traditional-Chinese and post on my blog? Re:Good articlePosted by on 02/24/2015 09:13am Unfortunately, we need to avoid copies of our content on other sites. Sorry.Reply	http://www.codeguru.com/columns/dotnet/why-overriding-tostring-is-a-good-idea.html	CC-MAIN-2016-50	refinedweb	902	66.88
GEOPRIV J. Winterbottom Internet-Draft CommScope Updates: 5222 (if approved) M. Thomson Intended status: Standards Track Skype Expires: March 5,April 4, 2013 R. Barnes BBN Technologies B. Rosen NeuStar, Inc. R. George Huawei Technologies SepOct 2012 Specifying Civic Address Extensions in PIDF-LO draft-ietf-geopriv-local-civic-06draft-ietf-geopriv-local-civic-07. Motivating Example . . . . . . . . . . . . . . . . . . . . 5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2. Specifying Civic Address Extensions . . . . . . . . . . . . . 5 3. Translating Unsupported Elements . . . . . . . . . . . . . . . 7 3.1. XML to DHCP Format Translation . . . . . . . . . . . . . . 7 3.2. Extension Civic Address Type (CAtype) . . . . . . . . . . 7 3.3. DHCP to XML Format Translation . . . . . . . . . . . . . . 8 3.4. Conversion Example . . . . . . . . . . . . . . . . . . . . 8 4. CAtypes Registry . . . . . . . . . . . . . . . . . . . . . . . 9 5. Civic Extensions . . . . . . . . . . . . . . . . . . . . . . . 10 5.1. Pole Number . . . . . . . . . . . . . . . . . . . . . . . 10 5.2. Mile Post . . . . . . . . . . . . . . . . . . . . . . . . 11 5.3. Street Type Prefix . . . . . . . . . . . . . . . . . . . . 11 5.4. House Number Prefix . . . . . . . . . . . . . . . . . . . 11 5.5. XML Extension Schema . . . . . . . . . . . . . . . . . . . 12 5.6. Extension examples . . . . . . . . . . . . . . . . . . . . 12 6. Using Local Civic Extension with the LoST Protocol . . . . . . 13 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 8.1. CAtype Registration for Extensions . . . . . . . . . . . . 15 8.2. Changes to the CAtype Registry . . . . . . . . . . . . . . 15 8.3. URN sub-namespace registration for 'urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr:ext' . . 15 8.4. XML Schema Registration . . . . . . . . . . . . . . . . . 16 8.5. Registration Template . . . . . . . . . . . . . . . . . . 16 8.5.1. Registration of the schema defined in this document . 17 8.6. Registration Policy and Expert Guidance . . . . . . . . . 18 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 1819 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 1819 10.1. Normative References . . . . . . . . . . . . . . . . . . . 1819 10.2. Informative References . . . . . . . . . . . . . . . . . . 1920 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 1920. Extension elements do not readily fit existing elements, as recommended in [RFC5774]. starts creators of extensions can advertise new namespaces and (XX) \| Length \| Namespace URI ... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . Namespace URI (continued) ... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \| Space (U+20) \| XML element local name ... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \| Space (U+20) \| Extension type value ... . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: XML Civic Address Extension CAtype which is defined in a manner that lets new civic elements be described in DHCP form by carrying the name space[XX] = lamp 2471 CAtype[XX] = pylon AQ-374-4(c) CAtype[XX] = airport LAX CAtype[XX] = terminal Tom Bradley CAtype[XX] = concourse G CAtype[XX] = suppport. which Post street named in this manner to be more easily represented. 5.4. House Number Prefix The civic schema defined in [RFC5139] provides> XML Example with Post Number and Mile Post >. 9: Corrected Location Validation Example 7. Security Considerations This document defines a formal way to extend the existing Geopriv civic address schema. No security threats are introduced by this document. Security threats applicable to the civic address formats are described in [RFC4776] (DHCP) and [RFC5139] (XML). 8. IANA Considerations This document alters the "CAtypes" registry on the "Civic Address Types Registry" page established by [RFC4776]. 8.1. CAtype Registration for Extensions IANA has allocated a CAtype code of XX for the extension CAtype. [[IANA/RFC-EDITOR: Please replace XX with the allocated CAtype]] 8.2. Changes to the CAtype Registry No further registration of numeric CAtypes in the Civic Address Types Registry is permitted. The column called "NENA" is removed. The column called "PIDF" is renamed to "Local Name". New columns are added named "Namespace URI", "Contact", "Schema" and "Type". New registrations use the registration template in Section 8.5. 8.3. URN sub-namespace registration for 'urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr:ext' This document calls for IANA to register> [[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX with the RFC number for this specification.]] <p>See <a href="[[RFC URL]]">RFCXXXX</a>.</p> </body> </html> END 8). The XML for this schema can be found as the entirety of Section 5.5 of this document. 8.5. Registration Template New registrations in the "CAtypes" registryCivic Address Types Registry require the following information: CAtype: The assigned numeric CAtype. All new registrations use the value XX. [[IANA/RFC-Editor: update XX] Existing registrations use their assigned value.. Type: If Type is "A", all clients SHOULD implement this element. If Type is "B", clients MAY implement this element..) Contact: The IESG (iesg@ietf.org); the GEOPRIV working group (geopriv@ietf.org). Specification: RFC4776 and RFC5139 Schema: urn:ietf:params:xml:schema:pidf:geopriv10:civicAddr Type: A 8.5.1. Registration of the schema defined in this document This section registers the following four new CATypes in the Civic Address Types Registry per the scheme in Section 5.5 whose parameters are identical except for their Local Names and Descriptions:"Descriptions: CAtype: The assigned numeric CAtype value is XX. [[IANA/RFC-Editor: update XX] Namespace URI: urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr:ext Local Name: PN Description: PN: Post number that is attributed to a lamp post or utility pole. Local Name: MP Description: MP: Mile Post a marker indicating distance to or from a place (often a town). Local Name: STP Description: STP: Street Type Prefix. Local Name: HNP Type: A 8, California Email:	http://zinfandel.tools.ietf.org/wg/geopriv/draft-ietf-geopriv-local-civic/draft-ietf-geopriv-local-civic-07-from-06.wdiff.html	CC-MAIN-2020-29	refinedweb	801	51.24
Hello World Lets write and deploy our first smart contract! The tutorial will be asking you to take various actions to interact with this code.). Before you get started with Flow, you need to understand how accounts and transactions are modeled. Accounts and Transactions Like most other blockchains, the programming model in Flow is centered around accounts and transactions. All persistent state and its interfaces (the ways to interact with it) are stored in accounts and all code execution takes place within transactions, which are blocks of code that are submitted by external users to interact with the persistent state, which includes directly modifying account storage. Each user has an account controlled by one or more private keys. This means that support for multi-sig wallets is built into the protocol by default. An account is divided into two main areas: - The first area is the contract area. This is the area that stores programs known as smart contracts that contain type definitions, fields, and functions that are related to a common functionality. This can also hold contract interfaces, which are basically program guidelines that other contracts can import and implement. This area cannot be directly read from in a transaction, but the owner of an account can directly overwrite contracts that are stored in it. - The second area is the account filesystem. This area is accessible in transactions and is where an account stores the objects that they own and the capabilities for controlling how these objects are accessed. Objects are stored under paths in the account filesystem. Paths consist of a domain and an identifier. Paths start with the character /, followed by the domain, the path separator /, and finally the identifier. For example, the path /storage/test has the domain storage and the identifier test. There are only three valid domains which represent the three areas in the account filesystem: storage, private, and public. Identifiers are custom and can be any name you want them to be to indicate what is stored in that path. - The storagedomain is where all objects (such as tokens or NFTs) are stored. It is only accessible by the owner of the account. - The privatedomain is like a private API. You can optionally store capabilities to any of your stored assets here. Only the owner and anyone they give access to can use these interfaces to call functions that are defined in your private assets. Users will commonly store private capabilities here that refer to other accounts private objects. - The publicdomain is kind of like your account's public API. The owner can store capabilities here that that anyone else in the network can access to interact with the private assets that are stored in the account. A Transaction in Flow is defined as an arbitrary-sized block of Cadence code that is signed by one or more accounts. Transactions have access to the /storage/ and /private/ domains of the accounts that signed the transaction and can read and write to those domains, as well as read and call functions in public contracts and the public domains in other users` accounts. Creating a Smart Contract We will start by writing a smart contract that contains a public function that returns "Hello World!". First, you'll need to follow this link to open a playground session with the Hello World contracts, transactions, and scripts pre-loaded: {" "} Open the Account 0x01 tab with the file called HelloWorld.cdc. HelloWorld.cdc should contain this code: pub contract HelloWorld { // Declare a public field of type String. // // All fields must be initialized in the init() function. pub let greeting: String // The init() function is required if the contract contains any fields. init() { self.greeting = "Hello, World!" } // Public function that returns our friendly greeting! pub fun hello(): String { return self.greeting } } A contract is a collection of code (its functions) and data (its state) that lives in the contract area of an account in Flow. Currently, accounts can only have one contract and/or one contract interface. The line pub let greeting: String declares a public state constant, using the pub let keywords, called greeting of type String. We would have used var if we wanted to declare a variable. The pub keyword is an example of an access control specification meaning that it can be accessed in all scopes, but not written in all scopes. You can also use access(all) interchangeably with pub if you prefer something more descriptive. Please refer to the Access Control section in the Glossary to learn more about the different levels of access control permitted in Cadence. The init() section is called the initializer. It is a function that is only run when the contract is created and never again. In this example, the initializer sets the greeting field to "Hello, World!". Next is a public function declaration that returns a value of type String. Anyone who imports this contract can call the public contract functions; i.e. the ones that have pub or access(all) specified. Now we can deploy this contract to your account and run a transaction that calls its function. Deploying Code Now that you have some Cadence code to work with, you can deploy it to your account. Make sure that the account 0x01 tab is selected and that the HelloWorld.cdc file is in the editor. Click the deploy button to deploy the contents of the editor to account 0x01. You should see a log in the output area indicating that the deployment succeeded. (Don't worry if the transaction number or block is different.) Deployed Contract To: 0x01 You'll also see the name of the contract show up in the selected account tab underneath the number for the account. This indicates that the HelloWorld contract has been deployed to the account. You can always look at this tab to verify which contracts are in which accounts, but there can only be one contract per account. Creating a Transaction Open the transaction named Transaction1.cdc Transaction1.cdc should contain this code: import HelloWorld from 0x01 transaction { // No need to do anything in prepare because we are not working with // account storage. prepare(acct: AuthAccount) {} // In execute, we simply call the hello function // of the HelloWorld contract and log the returned String. execute { log(HelloWorld.hello()) } } This is a Cadence transaction. A transaction can contain arbitrary code that imports from other accounts, interact with account storage, interact with other accounts, and more. To interact with a smart contract, the transaction first needs to import that smart contract by retrieving its definition from the address where it is stored. This imports the interface definitions, resource definitions, and public functions from that contract so that the transaction can use them to interact with the contract itself or with other accounts that utilize that contract. To import a smart contract from another account, you type the line: import {Contract Name} from {Address} Transactions are divided into two main phases, prepare and execute. - The preparephase is the only place that has access to the signing accounts' private AuthAccountobject. AuthAccounthas special methods that allow saving to and loading from /storage/and /private/, and creating /public/links to the objects in /storage/. - The executephase does not have access to AuthAccountand thus can only modify the objects that were removed in the preparephase and call functions on external contracts and objects. By not allowing the execute phase to access account storage, we can statically verify which assets and areas of the signers storage a given transaction can modify. Browser wallets and applications that submit transactions for users can use this to show what a transaction could alter, and users can have more confidence that they aren't getting fed a malicious or dangerous transaction via an application-generated transaction. You can see examples of why this is important in the FAQ You can have multiple signers of a transaction by clicking multiple account avatars in the playground, but the number of parameters of the prepare block of the transaction NEEDS to be the same as the number of signers. If not, this will cause an error. In this transaction, we are importing the contract from the address that it was deployed to and calling its hello function. In the box at the bottom right of the editor, select Account 0x01 as the transaction signer. Click the Send button to submit the transaction You should see something like this: "Hello, World!" Congratulations, you just executed your first Cadence transaction! :100: Creating a Resource Next, we are going to get some practice with an example that uses resources, one of the defining features in Cadence. A resource is a composite type like a struct or a class, but with some special rules. Open the Account 0x02 tab with file named HelloWorldResource.cdc. HelloWorldResource.cdc should contain the following code: pub contract HelloWorld { // Declare a resource that only includes one function. pub resource HelloAsset { // A transaction can call this function to get the "Hello, World!" // message from the resource. pub fun hello(): String { return "Hello, World!" } } init() { // Use the create built-in function to create a new instance // of the HelloAsset resource let newHello <- create HelloAsset() // We can do anything in the init function, including accessing // the storage of the account that this contract is deployed to. // // Here we are storing the newly created HelloAsset resource // in the private account storage // by specifying a custom path to the resource self.account.save(<-newHello, to: /storage/Hello) log("HelloAsset created and stored") } } Deploy this code to account 0x02 using the Deploy button. This is another example of what we can do with a contract. Cadence can declare type definitions within deployed contracts. Any account can import these definitions and use them to interact with objects of those types. This contract declares a definition for the HelloAsset resource. Let's walk through this contract: pub resource HelloAsset { pub fun hello(): String { return "Hello, World!" } } Resources are a composite type similar to a struct or a class because they can have any number of fields or functions within them. The difference is how code is allowed to interact with them. They are useful when you want to model direct ownership. Each instance of a resource exists in exactly one location and cannot be copied. They must be explicitly moved when accessed, making it difficult to lose accidentally. Structs from other conventional programming languages are not an ideal way to represent this ownership because they can be copied. This means a coding error can easily result in creating multiple copies of the same asset, which breaks the scarcity requirements needed for these assets to have real value. We have to consider loss and theft at the scale of a house, a car, or a bank account with millions of dollars, or a horse. Resources, in turn, solve this problem by making creation, destruction, and movement of assets explicit. init() { // ... This example also declares an init() function. All composite types like contracts, resources, and structs can have an optional init() function that only runs when the object is initially created. Cadence requires that all fields must be explicitly initialized, so if the object has fields, this function has to be used to initialize them. Contracts also have read and write access to the storage of the account that they are deployed to by using the built-in self.account object. This is an AuthAccount object that gives them access to many different functions to interact with the private storage of the account. In this contract's init function, the contract uses the create keyword to create an instance of the HelloAsset type and saves it to a local variable. To create a new resource object, we use the create keyword followed by an invocation of the name of the resource with any init() arguments. A resource can only be created in the scope that it is defined in. This prevents anyone from being able to create arbitrary amounts of resource objects that others have defined. let newHello <- create HelloAsset() Here we use the <- symbol. This is the move operator. The move operator <- replaces the assignment operator = in assignments that involve resources.. When a resource is moved, the old location is invalidated, and the object moves into the context of the new location. Regular assignments of resources are not allowed because assignments only copy the value. Resources can only exist in one location at a time, so movement must be explicitly shown in the code. Then it uses the AuthAccount.save function to store it in the account storage. self.account.save(<-newHello, to: /storage/Hello) A contract can refer to its member functions and fields with the keyword self. All contracts have access to the storage of the account where they are deployed and can access that AuthAccount object with self.account. AuthAccount objects have many different methods that are used to interact with account storage. You can see the documentation for all of these in the Storage section of the language reference or in the glossary. The save method saves an object to account storage. The type parameter for the object type is contained in <> to indicate what type the stored object is. It can also be inferred from the argument's type. The first parameter is the object that is being stored, and the to parameter is the path that the object is being stored at. The path must be a storage path, i.e., only the domain storage is allowed as the to parameter. If there is already an object stored under the given path, the program aborts. Remember, the Cadence type system ensures that a resource can never be accidentally lost. When moving a resource to a field, into an array, into a dictionary, or into storage, there is the possibility that the location already contains a resource. Cadence forces the developer to handle the case of an existing resource so that it is not accidentally lost through an overwrite. This is also why we can't let the execution reach the end of the block without doing anything with newHello, and why save would fail if there is already a resource at the specified path. In this case, this is the first transaction we have run, so we know that the storage spot at `/storage/Hello is empty. In real applications, we would likely perform necessary checks and actions with the location we are storing to to make sure we don't abort the transaction because of an accidental overwrite. Now that you have stored a resource in an account, you should see that resource show up in the Resources box below the editor. This box indicates which resources are stored in the selected account, and the values of the fields inside those resources. Right now, you should see that the HelloAsset resource is stored in account 0x02's storage and it has no fields. Interacting with a Resource Open the transaction named Transaction2.cdc. Transaction2.cdc should contain the following code: import HelloWorld from 0x02 // This transaction calls the "hello" method on the HelloAsset object // that is stored in the account's storage by removing that object // from storage, calling the method, and then putting it back in storage transaction { prepare(acct: AuthAccount) { // load the resource from storage, specifying the type to load it as // and the path where it is stored let helloResource <- acct.load<@HelloWorld.HelloAsset>(from: /storage/Hello) // We use optional chaining (?) because the value in storage // may or may not exist, and thus is considered optional. log(helloResource?.hello()) // Put the resource back in storage at the same spot // We use the force-unwrap operator `!` to get the value // out of the optional. It aborts if the optional is nil acct.save(<-helloResource!, to: /storage/Hello) } } This transaction imports the HelloWorld definitions from the account we just deployed them to and calls the hello() function of the stored HelloAsset resource. To remove an object from storage, we use the load method. let helloResource <- acct.load<@HelloWorld.HelloAsset>(from: /storage/Hello) If no object is stored under the given path, the function returns nil. When the function returns, the storage no longer contains an object under the given path. The type parameter for the object type is contained in <>. A type argument for the parameter must be provided explicitly, which is HelloWorld.HelloAsset here. The path from must be a storage path, i.e., only the domain storage is allowed. Next, we call the hello function and log the output. log(helloResource?.hello()) We use ? because the values in the storage are returned as optionals. Optionals are values that can represent the absence of a value. Optionals have two cases: either there is a value of the specified type, or there is nothing ( nil). An optional type is declared using the ? suffix. let newResource: HelloAsset? // could either have a value of type `HelloAsset` // or it could have a value of `nil` Optionals allow developers to account for nil cases more gracefully. Here, we explicitly have to account for the possibility that the helloResource object we got with load is nil. Using ? "unwraps" the optional before calling hello. Because ? is used when calling the hello function, the function call only happens if the stored value is not nil. In this case, the result of the hello function will be returned as an optional. However, if the stored value was nil, the function call would not occur and the result is nil. Next, we use save again to put the object back in storage in the same spot: acct.save(<-helloResource!, to: /storage/Hello) Remember, helloResource is still an optional, so we have to handle the possibility that it is nil. Here, we use the force-unwrap operator ( !). This operator gets the value in the optional if it contains a value, and aborts the entire transaction if the object is nil. It is a more risky way of dealing with optionals, but if your program is ever in a state where a value being nil would defeat the purpose of the whole transaction, the the force-unwrap operator is a good choice to deal with that. Refer to Optionals In Cadence to learn more about optionals and how they are used. Select account 0x02 as the only signer. Click the Send button to submit the transaction. You should see something like this: "Hello, World!" Creating References to Stored Resources In this example, we create a link and reference to your HelloAsset resource object, then use that reference to call the hello function. A detailed explanation of what is happening in this transaction is below the transaction code so, if you feel lost, keep reading! Open the transaction named Transaction3.cdc. Transaction3.cdc should contain the following code: import HelloWorld from 0x02 // This transaction creates a new capability // for the HelloAsset resource in storage // and adds it to the account's public area. // // Other accounts and scripts can use this capability // to create a reference to the private object to be able to // access its fields and call its methods. transaction { prepare(account: AuthAccount) { // Create a public capability by linking the capability to // a `target` object in account storage // This does not check if the link is valid or if the target exists. // It just creates the capability. // The capability is created and stored at /public/Hello, and is // also returned from the function. let capability = account.link<&HelloWorld.HelloAsset>(/public/Hello, target: /storage/Hello) // Use the capability's borrow method to create a new reference // to the object that the capability links to let helloReference = capability!.borrow() // Call the hello function using the reference // to the HelloAsset resource. // // We use the "?" symbol because // the value we are accessing is an optional. log(helloReference?.hello()) } } Ensure account 0x02 is still selected as a transaction signer. Click the Send button to send the transaction. You should see "Hello, World" show up in the console again. This is because we created a capability for the HelloAsset object, stored the capability in /public/Hello, borrowed a reference from the capability, and used our reference to call the hello method of the object. Let's break down what is happening in this transaction. First, we create a capability that is linked to the private HelloAsset object in /storage/: let capability = account.link<&HelloWorld.HelloAsset>(/public/Hello, target: /storage/Hello) The HelloAsset object is stored in /storage/Hello, which only the account owner can access. The owner might still want to let other people call the hello method, but not necessarily get full access to the actual HelloAsset object. This is what capabilities are for. Capabilities are kind of like pointers in other languages. They represent a link to an object in an account's storage. They are used to borrow a reference to the object, which can be used to read fields or call methods on the object they reference, but not to copy, move, or modify the object directly. To create a capability, we use the AuthAccount.link method to link a new capability to an object in storage. The type contained in <> is the restricted reference type that the capability represents. A reference is referred to by the & symbol. Here, the capability references the HelloAsset object, so we specify <&HelloWorld.HelloAsset> as the type. The first argument to the function is the path where you want to store the capability and the target argument is the path to the object in storage that is to be linked to. To get a reference to an object from the capability, we use the capability's borrow method. let helloReference = capability!.borrow() This method creates the reference as the type we specified in <> in the link function. Here we use the force-unwrap operator ( !) because the capability is an optional. If the capability is nil the transaction will abort. It also returns nil if the targeted storage slot is empty, is already borrowed, or if the requested type exceeds what is allowed by the capability. The reason we separate this process into capabilities and references is to protect against re-entrancy bugs where a malicious actor could call into an object multiple times. These bugs have plagued other smart contract languages. Only one reference to an object can exist at a time, so this type of vulnerability isn't possible for objects in storage. Additionally, the owner of an object can effectively revoke capabilities they have created by moving the underlying object. If the referenced object is moved, capabilities that are linked to it are invalidated. Now, anyone can call the hello() method on your HelloAsset object by borrowing a reference with your public capability in /public/Hello! Lastly, we call the hello() method with our borrowed reference: // Call the hello function using the reference to the HelloAsset resource log(helloReference?.hello()) Executing Scripts A script is a very simple transaction type in Cadence that cannot perform any writes to the blockchain and can only read the state of an account. It runs without permissions from any account. To execute a script, you write a function called pub fun main(). You can click the execute script button to run the script. The result of the script will be printed to the console output. Open the file Script1.cdc. Script1.cdc should look like the following: import HelloWorld from 0x02 pub fun main() { // Cadence code can get an account's public account object // by using the getAccount() built-in function. let helloAccount = getAccount(0x02) // Get the public capability from the public path of the owner's account let helloCapability = helloAccount.getCapability(/public/Hello) // borrow a reference for the capability let helloReference = helloCapability!.borrow<&HelloWorld.HelloAsset>() // The log built-in function logs its argument to stdout. // // Here we are using optional chaining to call the "hello" // method on the HelloAsset resource that is referenced // in the published area of the account. log(helloReference?.hello()) } This script fetches the PublicAccount object with getAccount. let helloAccount = getAccount(0x02) The PublicAccount object is available to anyone in the network for every account, but only has access to a small subset of functions that can only read from the /public/ domain in an account. Then, it gets the capability that was created in Transaction3.cdc. // Get the public capability from the public path of the owner's account let helloCapability = helloAccount.getCapability(/public/Hello) To get a capability that is stored in an account, we use the account.getCapability function. This function is available on AuthAccounts and on PublicAccounts. It returns a capability at the path that is specified. It does not check if the target exists, but the borrow will fail if the capability is invalid. After that, the script borrows a reference from the capability, specifying &HelloWorld.HelloAsset as the reference type to borrow as. let helloReference = helloCapability!.borrow<&HelloWorld.HelloAsset>() Then, the script uses the reference to call the hello function and prints the result. Lets execute the script to see it run correctly. Click the Execute button in the playground. You should see something like this print: > "Hello, World" > Result > "void" Good work! You've deployed your first Cadence smart contracts and used transactions and scripts to interact with them! Here are a few pointers on certain aspects of the Playground if you still need some clarification. Accounts The playground is initialized with a configurable number of default accounts when you open it. In the playground, you can select accounts to edit the contracts that are deployed for them by selecting the tab for that account in the left section of the screen. The contract corresponding to that account will be displayed in the editor where you can edit and deploy it to the blockchain. Transactions Once a contract has been deployed, you can submit transactions to interact with it. In the transactions selection section on the left side of the screen, you can select different transactions to edit and send. While a transaction is open, you can select one or more accounts to sign a transaction. This is because in Flow, multiple accounts can sign the same transaction, giving the access to their private storage. If multiple accounts are selected as signers, this needs to be reflected in the signature of the transaction to show multiple signers: // One signer transaction { prepare(acct1: AuthAccount) {} } // Two signers transaction { prepare(acct1: AuthAccount, acct2: AuthAccount) {} } If you want more practice, you can run some of the previous transactions on new accounts to explore some different interactions and potential error messages. Fungible Tokens on Flow Now that you have written and launched your first smart contract on Flow, you're ready for something more complex!	https://docs.onflow.org/tutorial/cadence/02-hello-world/	CC-MAIN-2020-45	refinedweb	4,449	54.73
The Ethernet library grew in size several KB from 0022 to 1.0, which is a big deal when you only have 32 KB to play with. You can save about 2 KB by compiling out DNS support: Wrap the following pieces of code in #if WITH_DNS - Dns.cpp and Dns.h: The entire file - EthernetClient.h and EthernetClient.cpp: int connect(const char* host, uint16_t port) - EthernetUDP.h and EthernetUDP.cpp: int beginPacket(const char host, uint16_t port) - Client.h: virtual int connect(const char host, uint16_t port) - Udp.h: virtual int beginPacket(const char *host, uint16_t port) Add #include "EthernetUDP.h" to EthernetUDP.cpp, since it’s currently relying on the indirect include from Dns.h.	http://michaelnoland.com/tag/dns/	CC-MAIN-2018-17	refinedweb	118	63.56
Facebook Wall Posts On Website?Jan 25, 2011 08:25 AM Need the steps to show my facebook wall posts on my asp.net webiste/View 3 Replies Need the steps to show my facebook wall posts on my asp.net webiste/View 3 Replies I am using Facebook Toolkit. I have appKey and appSecret, but I dont want that visitor need to conenct to facebook. I will use my login/passwork to get my wall posts.View 1 Replies View Related Basically, I would like to include my latest Wall posting on my website. But, so far, everything I have read needs the visitor to the site to log-in to Facebook which, in theory, would then retrieve their latest Wall post. In prinicpal, I guess it would be like an RSS Feed.View 1 Replies View Related I'm using an ASP.NET Facebook Developers Toolkit () on an external website, and I'm also the admin of a facebook fan page for the website. Users on my website (may or may not be facebook users) create content articles. I would like to hook up these articles to the Facebook fan page, so that, when they write the article, then ones with FB accounts can sign into FB and post on the Fan page. I'm sure they would need to be a fan first. I like to send messages when I want from my aspx webpage. I used the different examples and used FaceBook API 3.1. I am getting error as "service temporarily unavailable". I have assigned AppKey, Secret Key and session key. My sample code is below. using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using Facebook; using Facebook.Web; using Facebook.Rest; using Facebook.Session; using Facebook.Utility; using Facebook.BindingHelper; using Facebook.Schema; using Facebook.Web.FbmlControls; using Facebook.Session.DesktopPopup; namespace FaceBookApp { public partial class _Default : System.Web.UI.Page { private const string ApplicationKey = "MY_APP_KEY"; private const string SecretKey = "MY_SECRET_KEY"; private Api fbAPI; private ConnectSession _connectSession; // private List<EventUser> _eventUsers; protected void Page_Load(object sender, EventArgs e) { } protected void Button1_Click(object sender, EventArgs e) { _connectSession = new ConnectSession(ApplicationKey, SecretKey); _connectSession.SessionKey = "MY_SESSION_KEY"; if (!_connectSession.IsConnected()) { // Not authenticated, proceed as usual. //lblStatus.Text = "Please sign-in with Facebook."; } else { // Authenticated, create API instance fbAPI = new Api(_connectSession); string response = fbAPI.Stream.Publish("publish steven on facebook."); } } } } The error message is confusing. It must be a very simple solution. I don't know what I am missing. Here is the facebook exception. {"Service temporarily unavailable"} i'm trying to figure out how to create a message wall similar to facebook or myspace, only much more simple, just txt messages. I've looked around and i can't really find any tutorials or posts on how to do this. if anyone can point me in the right direction or provide me with some links. I mean, even something as simple as you see on practically every site out there, where at the bottom the user can leave a comment or feedback and it posts it to the page.View 1 Replies View Related I am making a db schema for facebook like wall structure. I need to save wall posts, share a link, share a video stuff into my database. Till now I am able to make this schema : GO CREATE TABLE [Wall] ( [ID] [int] NOT NULL IDENTITY(1, 1) , [PostText] [nvarchar](MAX) [PostedByUserID] [int] NULL , [PostedOnUserID] [int] NULL , [DateCreated] [datetime] NULL ) GO Next I have to add the schema for adding the "share a link" and "share a video" feature. GO CREATE TABLE [Wall] ( [ID] [int] NOT NULL IDENTITY(1, 1) , [WallText] [nvarchar](MAX) [PostedByUserID] [int] NULL , [PostedOnUserID] [int] NULL , [DateCreated] [datetime] NULL, [SharedLink] [nvarchar](1024) NULL , [SharedLinkTitle] [nvarchar](512) NULL , [SharedLinkDesc] [nvarchar](512) NULL , [SharedLinkImageSrc] [nvarchar](512) NULL ) GO Now with this schema: 1st case: When the wall post is inserted the [SharedLink], [SharedLinkTitle],[SharedLinkDesc], [SharedLinkImageSrc] columns will be inserted as null and rest of the columns will have the values. 2nd case: When the "link shared" is inserted the "[WallText]" column will be inserted as null and rest of the columns will have the values. For my case 70% of the time the wall post will be made and 30 % "links" will be shared which means 70 % of the cases [SharedLink], [SharedLinkTitle],[SharedLinkDesc], [SharedLinkImageSrc] will be inserted as null. Now my concern is that is it okay to keep the null columns inserted or I should go for a separate table for "shared a link" purpose and have the separated table like this: GO CREATE TABLE [LinkShared] ( [ID] [int] NOT NULL IDENTITY(1, 1) , [PostedByUserID] [int] NULL , [PostedOnUserID] [int] NULL , [SharedLink] [nvarchar](1024) NULL , [SharedLinkTitle] [nvarchar](512) NULL , [SharedLinkDesc] [nvarchar](512) NULL , [SharedLinkImageSrc] [nvarchar](512) NULL ) GO I have to go in similar manner to add the schema for sharing the videos further. Please guide me in which direction should I move? I'm just wondering what's the best way to implement a threaded conversation like the Facebook Wall where the comments are displayed under each post, and older comments are collapsed and expandable. My instinct is to use a nested datalist, but I think that might take a toll on performance.View 2 Replies View Related I am using facebook graph API to get the loged in user token [URL] Also, I am grabbing these facebook params "publish_stream,email,offline_access" when any user logs into my website. If i have 100 uses who logged into my website, How can i post an offline message onto their wall and if possible to their friends wall too. let me if this can be done?View 2 Replies View Related I'm trying to recreate a facebook-like reply posting Wall with multiple users; 'm pretty new to the web environment but I have many years of development expierence so I should understand most of what you throw at me aanyone can put me in the right direction what type of script/lib/classes I should check. or even better some example code.View 1 Replies View Related I want Post to Wall Post functionality in facebook fan page application. I am developing it using ASP.Net. I am using javascript sdk and applying strem.publish method. Below is th code which i have used. [Code].... I need to post on a website the wall notifications of a Facebook group, the group and the website belong to the same entity. I've looked at many of the options available, but I would apreciate if someone with a bit Facebook developing experience told me what is the best path (most straighforward). The website is not intented to interact with Facebook in any other way, there would exist no Facebook login button, and this one wall would be the only one being consulted. I've looked at the possibility of grabbing an rss feed from the wall, but that option doesn't seem to exist. The website is being done with asp.net (c#).View 2 Replies View Related I've integrated my website with Facebook Connect, authorization/single-sign on all working great. Now im trying to post something to the user's wall, which im having some problems with. First of all, im using the "old" JavaScript API (FeatureLoader.js). These are the Graph API URL's im using: private const string UserDetails_Url = @"{0}?access_token={1}"; private const string Feed_Url = @"{0}/feed?access_token={1}"; private const string TokenExchange_Url = @"?{0}"; I'm using the TokenExchange_Url URL to receive the unique user OAuth token to make calls with. This is working fine, because a) i receive the token back, and b) i can issue HTTP Get Requests to the Graph API (i.e UserDetails_Url) and it works fine. But, i cannot Post to the User's wall using the Feed_Url.I'm pretty sure the issue is i haven't got the appropriate user permissions to post to a wall (i.e facebook-side setting). Now, i realise i can use the fbPublish API method client-side to do this, but i want to do it server-side with the Graph API. I wont bother showing my code which attempts the call to the Graph API to post to the user's wall, as its pretty straightforward (HttpWebRequest, set method to "POST', set content type/length, write bytes to Stream, etc). I think the problem is i need the user to grant my aplpication "publish_stream" extended permissions. The Facebook Graph API doco says to do this in your authorization request:? client_id=...& redirect_uri= scope=user_photos,user_videos,publish_stream Which confuses me because im using the following URL to get the OAuth token: Am i using the wrong Token Exchange URL? Why is there two different URL's to seemingly get the same piece of information? Yes - i have read the Facebook API doco (numerous times), and yes i have read other similar SO questions, but they all result in using the client-side API to publish to wall, i want to do it server side. For the actual "Facebook Connect" button, i'm using the standard FBML: <fb:login-button<a id="RES_ID_fb_login" class="fbconnect_login_button"><img id="RES_ID_fb_login_image" src="" alt="Connect"></a></fb:login-button> When i click this (and not logged into Facebook), it pops up a window which the user can login. But it doesnt have the "Request Extended Permissions" dialog - shouldnt it? Or is that another popup i need to manually trigger? So to sum up, here are my questions: How do i grant extended permissions to publish to the user's wall?What is the correct URL for obtaining an OAuth token?Is there a definitive source for showing how to post to a user's wall using server-side Graph API calls? I am making a mini-facebook website, and have been implementing a users personal wall where members can write on anyones wall.I don't want users to be able to write on OTHER users wall unless they are "friends". So i have created a table:- Quote: hussaini_friends {friend_id, user_id, f_user_id, status, date_added} So in the above table, i have user_id and f_user_id. Then there is a status column. This will show the status of the 2 users. (either accepted or declined).. Now what i need to do is to check if the status of the 2 users is "accepted". If so then the users wall will be displayed. Otherwise the user will be asked to add the user as a friend. Currently i do this:-PHP Code: "SELECT (hussaini_comments.comment_id) AS CID, " + "(hussaini_comments.comment) AS Comment, " + "(hussaini_comments.user_id) AS UID, " + [code]... This currently gets the details to pull out the information of the wall that belongs to a specific user. Now i need to add to the SQL so that it checks to see if the users are friends. Would it be better it i have a separate SQL statement to check if the users are friends then show their details..? I am creating Fan page and application for Post something in Fan page wall from ASp.net page. But Text get post Nicely. But Images and attachments not get post in my wall. Is ther any way to Pass HTML code from asp.net to post in my Facebook Fans page Wall.View 2 Replies View Related i have managed to develop a status wall some what similar to facebook, using Repeater Controls- Parent Repeater is bound to the status and the child repeater is bound to the comments inside that status. I am strugling to implement the following solution- hiding and displaying a btnDeleteComments - depending of the owner of the comment- i.e. only owner of the wall and those who leave the comment can only delete that comment. Status X Comment A - left by member John Comment B - Left by Member Doe Comment C - Left by Member Harry The owner of the wall can delete all comments, and only John can delete comment A, Doe can delete comment B and so on Here is what i have tried so far 1. fill a data set with two tables and relate them (table one = status, Table 2 = comments of that status) 2. data bind the repeater to this data set 3. here is the HTML of the child repeater <asp:Repeater <HeaderTemplate> </HeaderTemplate> <ItemTemplate> <asp:Table <asp:TableRow> <asp:TableCell> <asp:Image </asp:TableCell> <asp:TableCell> <asp:TextBox </asp:TextBox> <asp:Label </asp:Label> </asp:TableCell> <asp:TableCell <asp:Button </asp:TableCell> </asp:TableRow> </asp:Table> <br /> </ItemTemplate> </asp:Repeater> The higlighted bit is causing the cast invalid error- i thought this would do the trick, by deafult all the delete buttons next to each comment is hidden for members other then the owner of the wall- and only if they are the one who left the comment will teh delete button be visible- <%# DataBinder.Eval(Container.DataItem, "["ViewersComment"]")%>' The SQL which retreives the comments for a specific status, also retrieves a column2 ViewersComment which is either 'true' of 'false', indicating wether that comment was left by this person viewing the status wall- I have to create facebook style wall in my project. So far I assume that I will get X(the number that needs to be shown be default) number of wall posts from database, bind them to some control like Repeater and add update panel in each row in repeater so that only the portion of page only related to that post is updated once any new comment is added in that post. Now, since I am new to AJAX so cant figure out how to display the "older post" link functionality there. As we have link at the bottom of facebook wall which once clicked appends the certain number of older posts at the end of the wall. Similarly, once a new post is added by someone, it gets added at the top of the wall, how can I acheive that so tha only the limited portion at the top of the wall gets refersed and updated instead of whole page post back. i have a group page. i am creating a website for the group and they want to be able to see the recent facebook updates (what you see on the group's facebook wall) on their website. is this possible without having to have a facebook popup login and just programatically pass in my login information?View 1 Replies View Related I am doing my final year project and have decided to make a website in asp.net. For that I'll be using Micrsoft Visual Studio 2008. I'm making a Real ESTATE properties website. I want to know how to localize or create new posts in asp.net( like in WORDPRESS) and also when I hit SEARCH it should search for the desired keyword or the searched post. If post is not possible then it should display pages... how to publish posts automatically in web site page (asp)?View 5 Replies View Related I've been reading through the fb developer api documentation and I'm trying to find out what would be the easiest way to post information on a website to the website's own facebook page. for instance - the assumed workflow is like this: an admin user adds new content to the company website - and once submitted that content should automatically appear as a link on the company's facebook page. Do I use the API, facebook Connect, a facebook Share button etc. Looking for some recommendations based on my assumed workflow. Project will be coded in c# (although I'm really looking for recommendations of which tool to use from someone's experiences with the api) how to use a facebook share from my website. I.e if I want this post to be on facebook, how do I incorporate it[URL]View 2 Replies View Related i want to use localhost for developing website facebook application using the graph api. i working in asp.net c# in the previous api of facebook i was abe to write the in the connect url at the application settings. now it dosent work.it keeps telling me An error occurred with application name. Please try again later. ** if i upload the website, and use the website coonect url, it is working. how can i add chat application like facebook in my social networking site? i need to add chat application in my project just like facebook chat how can i create in asp.net? Im testing something on a MojoPortal where i need to seperately add a Facebook connect button and make the user get registered with the website's registration! How do i do that?View 2 Replies View Related I have a page that have 5 to 10 photos of a person, If some user comes into this page he should see facebook "Like" button next to each photo on that page. I have installed Javascript SDk on my site, I can use XFBML also. Just post me some sample code if you have any? I want to something like this. If Write one scrap and click on postbutton , I want to write that scrap in twitter,facebook,orkut and mywebiste. In all above i have accounts. In my facebook canvas applikation, i store the access token in session. (I use ASP.NET MVC) But i want to store the access token in a database along with the facebook user id that i can save different access tokens for different facebook users accessing my application. So when i query the facebook user id and if it doen't return any access token, i request permissions and get the access token for that user. How do i access the Facebook UserID for the user accessing my canvas application before doing any authentification? I'm trying to create a basic application, i created facebook application before but everything has been changed. I looked every where to create a basic application, but now i'm getting mad because there isn't any working sample. Because of the changed links, facebook api changes, facebook wiki changes i couldn't find a working copy. write a basic app that gets permission to write user name to screen in facebook developer toolkit asp.net. I looked computerbeacon.net, codeplex, and some other pages but i couldn't succeed. Edit: I' m adding some screenshots and some codes, it will may be you to find my problem. [code].... how can i pull facebook's friends status and list etc using facebook api and show that all in my asp.net page?? like we use twiter api? actually i googoled a lot bt unable to fine any good refrence.. most of them are like creating page(canvas) page there at facebood developer site and for focaebok application.View 1 Replies View Related i created a mathod facebookInfo(string username,string password) ,so i received username and password but after receiving its not possible to login at server side,because ther is only one way to connect to facebook using facebook api ie. facebookservie.ConnectToFacebook(); and its open IE browser,so there is any way to login automatically and get session,using any javascript or nay other way at server side using ASp.net in C#. if i want my facebook connect site to access user information about a facebook user, is it necessary for that user to be logged in?View 2 Replies View Related Anyone know about this? I am trying to embed that plugin and am lost. I have already tried this and this is not working at all. 1 Replies View Related I have developed a niche photo sharing website, where user submit their photographs. I want to add a "Facebook like button" just below this images so that when somebody clicks it, it get displayed on their facebook profile. I got the FBML code for the "Like" button from the facebook developers site and I pasted it on the site. However, when I click the like button, it produces following output. User X likes "title of the page" on "" The above update is purely text. However, what i want is that the facebook update should also display the image which the user has liked along with the text. how to get the facebook login service?Is it free or any payment mode.I would like use this in my site.View 3 Replies View Related I am trying to implement facebook like button on my website. The first four lines in the code is already there on my site after the end of the "" tag. To implement the "Like button" i have added the second script (Line five to the end) and ran the application. Its giving me an error as "Microsoft Jscript runtime error:'_onLoad' is null or not an object" <script type="text/javascript" src=""></script> <script type="text/javascript"> FB.init("myapikey", "xd_receiver.htm", { "reloadIfSessionStateChanged": true }); [Code]..... I would like to programatically (sp?) open a box asking my users to type in what to publish, but I want it to look like Facebook's own boxes.View 1 Replies View Related I am making a mini facebook style website. I am in the process of implmenting the users "Wall" where users who are the users friends can insert comments etc..Now there is one thing i cant think of how to do. Basically each wall will be specific to a certain user. And all the walls will have different comments on them.Now i have managed to implement inserting comments etc on a users wall. BUT the problem is that it pulls out the comments for ANY user who is logged in.So basically the logic here would be that a wall belongs to a specific user, which contains comments made by users.View 4 Replies View Related i have a partial website up as im having extreme difficultys trying to figure out how to save some information You can log into the site with any credentials atm there is no functionality for it atm, it will bring you to the users profile page which has a wall posting part to it, you can write on your wall similar to facebook. The part im trying to get my head around is how to save that data so it stays on the wall im using asp and mysql? Can any one help? I'm just returning to .NET and I am still getting used to the structure and setup for MVC.. I have a query about partial views /user controls - (i guess). I want to create a partial view of thumb image display (grid-wall like) reusable across the site/solution. The model for this already serves detail pages across the site. I want to use one attribute of the model collection e.g. 'model.thumbImage' to create a grid of thumb images. My question is do I have to create a separate controller for this partial view e.g. Controllers/GridController.cs and then a view Views/Grid/index.ascx ? What is the best way to apprach this? I do not want the grid to be served/ routed directly i.e grid/index.ascx.	http://asp.net.bigresource.com/Facebook-wall-posts-on-website--7KQXryMYl.html	CC-MAIN-2015-18	refinedweb	3,891	63.29
QtSerialPort and memory usage Hi, I have this following code reading the serial port on Windows. As the application keeps reading the serial port byte after byte, I do see that the memory usage keeps on going up. But if I do comment out the read(), the memory usage is stable and constant. Is it something that I am missing or doing incorrectly ? Thanks, #include <QtSerialPort/QSerialPort> #include <QCoreApplication> #include <QDebug> int main(int argc, char argv[]) { QCoreApplication a(argc, argv); QSerialPort port; char dt; port.setPortName("COM13"); if (!port.open(QIODevice::ReadWrite)) { qDebug() << "Open" << port.portName() << "failed"; return -1; } qDebug() << port.portName() << "Open";); } } return a.exec(); } +1 for running able code. Win 7, 64. mingw. Qt 5.5 memory seems stable. how long to watch ? I am running Win 7 SP1 32bit Version 6.1.7601 QT 5.5.0, QT creator: 3.4.2 revision b57ac109a2 MinGW 2013072200 The memory usage, seen as with Task Manager is as follows: starts at about : ~2.4M @ about 10Sec : ~32M @ 60Sec : ~64M @ 120Sec : ~96M @ about 300Sec : ~227M I dont know, just a thought, as though each read() is not freeing up read memory within the library. Is that possible situation ? But then, lot of other people should also be facing the same situation, but I guess that isnt the scenario. Thanks - mrjj Lifetime Qt Champion last edited by mrjj @codeaway Well bugs are always possible. Also tried at work. After 25 sec, still have same Memory. So I cannot reproduce it easy. Is it a real comport or a virtual one ? both tested here are virtual. (com1.) I wonder if it could be your driver . can you reproduce it on other system ? update: tried on system with real comport. still stable mem. sorry. I am using a BAFO USB to serial converter as seen here: Trying to eliminate some unknown possible situations: Assuming for a moment that there is a hardware bug with the USB to serial converter hardware/driver The same serial hardware is connected to the same converter and is read with Terra Term (Version 4.76) It's memory usage (Private Working set) remains stable at 8,668K reading the same data. I just wonder why it is showing stable memory usage. I wondered, how the other QtSerialExamples behaved; Tried with the simple terminal example D:\Qt\Qt5.5.0\5.5\Src\qtserialport\examples\serialport\terminal\release> Even terminal shows a memory usage increment, much like the code snippet that's under scrutiny. I wonder, how Terra Term is able to cope with a consistent memory usage Updated the original code to print out the memory usage. Updated code output screencap shows the usage memory incrementing: For sake of completeness, including the updated code in here #include <windows.h> #include "psapi.h" #include <QtSerialPort/QSerialPort> #include <QCoreApplication> #include <QDebug> #include <QDateTime> int main(int argc, char argv[]) { PROCESS_MEMORY_COUNTERS_EX pmc; QCoreApplication a(argc, argv); QSerialPort port; char dt; port.setPortName("COM13"); if (!port.open(QIODevice::ReadWrite)) { qDebug() << "Open" << port.portName() << "failed"; return -1; } qDebug() << port.portName() << "Open @" << QDateTime::currentMSecsSinceEpoch();); GetProcessMemoryInfo(GetCurrentProcess(), (PROCESS_MEMORY_COUNTERS*)&pmc, sizeof(pmc)); qDebug() << "Read @" << QTime::currentTime() << "Used:" << pmc.PrivateUsage; } } return a.exec(); } Hmm if tera works with same usb serial then it cant be the driver. Im also using serial over usb. Tried to run updated code. just to ebe sure. get link error undefined reference to `GetProcessMemoryInfo@12' What should i put in .pro to run ? something with -lpsapi. Mostly on linux so not sure with syntax Yes. Sorry, missed the .pro file. inlined it #------------------------------------------------- Project created by QtCreator 2015-10-06T21:35:43 #------------------------------------------------- win32:LIBS += -lpsapi QT += core serialport QT -= gui TARGET = Serial CONFIG += console CONFIG -= app_bundle TEMPLATE = app SOURCES += main.cpp - mrjj Lifetime Qt Champion last edited by mrjj works. Still stable. Do you have input on the serial ? I will connect something that sends data. just to check. How do you make it open console also ? Here its just a process. Update: ignore last question. just saw its QDebug Also, with input , I do see mem raising. Testing more ok, slowly from 12k to 17k. over time when it has input. Also the pmc changes. So yes. I see the same. Will leave it running for some time to check if it stops. Yes, I do have a microcontroller reading values and outputting to serial port continuously. Actually, the application I created is a console application. The info is output with QDebug additionally. Nevertheless, you can choose to output with console without QDebug too. CONFIG += console in the .pro file Create a output stream in the actual code QTextStream out(stdout); and output whatever required out << "Something" << endl; @codeaway Ok i killed it at 25K. Since we just reading a char, it cant be in the us that leaks. I must agree it seems odd. Can you please test same with the virtual com0com: A signed driver for x64: How should I configure com0com ? Just create a pair with the "use port class" and "eneble buffer overrun" (via setupg.exe ui) just as a virtual port or as a loop ? as a two virtual ports. . e.g. COM1 as receiver for qserialport and COM2 as sender for other software (e.g. I have used Termite app to send). UPD: Yes, I too can reproduce this memory leak.. Yeah, reproduced it with com0com and termite. Attached link to screencap After a detailed analysis, it looks as though all QtSerialPort examples also face this issue. @codeaway Yep got ever increasing mem use also with com0com. If time permits I try the examples too. Probably it is a bug of QWinOverlappedIoNotifier : Let's wait for more info about..	https://forum.qt.io/topic/59472/qtserialport-and-memory-usage	CC-MAIN-2022-33	refinedweb	944	61.02
I was going through Frontity, i did not find anything regarding forms like how i can create forms in my Wordpress and use them in my theme? any ideas? Contact Forms like contact form 7 I think @imranhsayed and @smit.soni22 are about to start working on a CF7 package for Frontity Once that’s done, it will be as easy as adding that package in your frontity.settings.js file. No coding required. I’ll keep you updated. Yup we are on it. Thanks @luisherranz Will update on this soon That will be amazing because the only thing remaining in the introduction to frontity was the contact form. When this will be done many front end developers like me will have their life at ease What about custom forms (it doesn’t need to be present at wp-admin) with custom POST endpoints? Can I see any example of such form at work (code appreciated) ? With Frontity, you are in the React world, so you can create whatever you want and connect it to whatever service you want. The only two things I’d recommend you are: - Use fetchinstead of axiosor superagent, because it won’t make your app bigger. We made sure it works in both the server and the client if you import it from "frontity": import { fetch } from "frontity"; - Use Frontity’s state manager to simplify your components instead of internal state: This is a rough example, but something like this: const myTheme = { roots: { theme: Theme }, state: { theme: { form: { sending: false, succeed: false, error: false, fields: { name: "", email: "", } } } }, actions: { theme: { setField: ({ state }) => ({ name, value }) => { state.theme.form.fields[name] = value; }, submitForm: async ({ state }) => { state.theme.form.sending = true; try { const response = await fetch("http...", { }); const body = await response.json(); // Do something with the response of the form. state.theme.form.sending = false; state.theme.form.succeed = true; } catch (error) { state.theme.form.sending = false; state.theme.form.error = error.message; } } } And something like this for the <Form> const Form = ({ state, actions }) => { return ( {!state.theme.form.succeed ? ( <form onSubmit={event => { event.preventDefault(); actions.theme.submitForm(); }> <input name="name" placeholder="Your name" value={state.theme.form.fields.name} onChange={event => { actions.theme.setField({ name: "name", value: event.target.value }); }} /> <input name="email" placeholder="Your email" value={state.theme.form.fields.email} onChange={event => { actions.theme.setField({ name: "email", value: event.target.value }); }} /> <input type="submit" value="Send" disable={state.theme.form.sending} /> {state.theme.form.error && <div>Something went wrong: {state.theme.form.error}</div> </form> ) : ( <div>Form sent!</div> ) ); };	https://community.frontity.org/t/contact-forms-like-contact-form-7/610	CC-MAIN-2019-43	refinedweb	422	51.44
Hi again, J.Pietschmann wrote: > I suggest to check your SAX stream first whether all elements are > properly closed. Try to feed it as a SAXSource to an identity XSL > transformation (use TransformerFactory.newInstance().newTransformer()). > The serialized file will be always well-formed (the transformer > closes open elements for you) but you could check for suspicious > omissions at the end. > I did what you suggest and also tried with Megginson's XMLWriter. In both cases, the original XML document (before XSLT transformation) and the FO document look OK (Megginson's writer does not alter/fix the SAX event stream.) I compared the debug traces generated by FOP in command-line mode and embedded mode, they're exactly the same. I remove the setting of "namespace-prefixes" in Starter.java. No change except that FOP can now run with Saxon! At least this is good news!!! Finally I removed all refences to external graphics, thinking it may be a problem of URI resolution: The PDF is smaller but Acrobat still complains the same! Can you think of any place in the code where I could set a breakpoint/trace to get more information about what's going on? TIA Laurent --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]	https://www.mail-archive.com/fop-dev@xml.apache.org/msg06156.html	CC-MAIN-2018-17	refinedweb	211	64.51
0 hello everyone, I am having a major problem with this assignment that asks to create a function whose input is a reference to an input file, which asks user to enter a file name to open for input, then checks to see where the file opened successfully. the function returns nothing. I tried implementing the code so far, however for some reason it doesnt even open a file. The file is saved in the same directory as the program. I have know idea whats going on. Please help! #include<iostream> #include<fstream.h> #include<string> using namespace std; int main() { ifstream inFile; string inFileName; cout << "Enter a filename: "; cin >> inFileName; inFile.open(inFileName.c_str()); system ("pause"); return 1; }	https://www.daniweb.com/programming/software-development/threads/430217/ifstream-function-check-if-file-opens	CC-MAIN-2017-04	refinedweb	119	63.7
puts - Man Page output of characters and strings Synopsis #include <stdio.h> int fputc(int c, FILE stream); int putc(int c, FILE stream); int putchar(int c); int fputs(const char restrict s, FILE restrict stream); int puts(const char *s); Description fputc() writes the character c, cast to an unsigned char, to stream. putc() is equivalent to fputc() except that it may be implemented as a macro which evaluates stream more than once. putchar(c) is equivalent to putc(c, stdout). fputs() writes the string s to stream, without its terminating null byte ('\0'). 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at. Referenced By curs_addch.3x(3), curs_termcap.3x(3), curs_terminfo.3x(3), fgetc(3), fgetln.3bsd(3), flockfile(3), fputwc(3), fputws(3), gets(3), getw(3), libraptor(3), printf(3), putwchar(3), setbuf(3), stdio(3). The man pages fputc(3), fputs(3), putc(3) and putchar(3) are aliases of puts(3).	https://www.mankier.com/3/puts	CC-MAIN-2022-27	refinedweb	177	75.2
Mahmoud wants to send a message to his friend Ehab. Their language consists of n words numbered from 1 to n. Some words have the same meaning so there are k groups of words such that all the words in some group have the same meaning. Mahmoud knows that the i-th word can be sent with cost ai. For each word in his message, Mahmoud can either replace it with another word of the same meaning or leave it as it is. Can you help Mahmoud determine the minimum cost of sending the message? The cost of sending the message is the sum of the costs of sending every word in it. The first line of input contains integers n, k and m (1 ≤ k ≤ n ≤ 105, 1 ≤ m ≤ 105) — the number of words in their language, the number of groups of words, and the number of words in Mahmoud's message respectively. The second line contains n strings consisting of lowercase English letters of length not exceeding 20 which represent the words. It's guaranteed that the words are distinct. The third line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 109) where ai is the cost of sending the i-th word. The next k lines describe the groups of words of same meaning. The next k lines each start with an integer x(1 ≤ x ≤ n) which means that there are x words in this group, followed by x integers which represent the indices of words in this group. It's guaranteed that each word appears in exactly one group. The next line contains m space-separated words which represent Mahmoud's message. Each of these words appears in the list of language's words. The only line should contain the minimum cost to send the message after replacing some words (maybe none) with some words of the same meaning. 5 4 4 i loser am the second 100 1 1 5 10 1 1 1 3 2 2 5 1 4 i am the second 107 5 4 4 i loser am the second 100 20 1 5 10 1 1 1 3 2 2 5 1 4 i am the second 116 In the first sample, Mahmoud should replace the word "second" with the word "loser" because it has less cost so the cost will be 100+1+5+1=107. In the second sample, Mahmoud shouldn't do any replacement so the cost will be 100+1+5+10=116. #include<cstdio> #include<string> #include<algorithm> #include<map> #include<iostream> using namespace std; const int maxn=1e5+10; typedef long long ll; map<string,ll> M; ll a[maxn],b[maxn]; string str[maxn]; int n,m,k; ll ans=0; int main() { cin>>n>>k>>m; for(int i=0;i<n;i++) { cin>>str[i]; } for(int i=0;i<n;i++) { cin>>a[i]; } int x; for(int i=0;i<k;i++) { cin>>x; ll min=1e10; for(int j=0;j<x;j++) { cin>>b[j]; b[j]--; if(a[b[j]]<min) min=a[b[j]]; } for(int j=0;j<x;j++) {M[str[b[j]]]=min; //cout<<M[str[b[j]]]<<"#"<<endl; } } string s; for(int i=0;i<m;i++) { cin>>s; ans+=M[s]; //cout<<ans<<'!'<<endl; } cout<<ans<<endl; return 0; }	https://blog.csdn.net/NicoleYWJ/article/details/79967861	CC-MAIN-2018-30	refinedweb	559	75.64
Because I'm a lucky man, i'm convinced to my hosting provider to setup python so I can play with django ;) I have a reseller account, so I plan to reuse my first django website (a portal of colombian food) But, this guys are asking how setup the thing. Rigth now, this guys are already installed python I know this: But is a instruction from MS... so how can be good (no! is not becuase is from MS: serving CGI this way is bad performance!) I want to provide a good advice: My parent hosting company is given to me a great favor so I don't wanna put the support staff in troubles... This is for run in a shared hosting environemnt so must be bullet proof. Because that, I think is impossible to demand a apache config here. So, what are the alternatives? (excluding getting a linux box) - Is FastCGI the rigth answer? - Existe a stable ISAPI dll? > - Is FastCGI the rigth answer? > - Existe a stable ISAPI dll? On 24/05/2006, at 8:08 AM, mamc...@gmail.com wrote: > So, what are the alternatives? (excluding getting a linux box) namevirtualhost * <virtualhost *> servername i-need-iis proxypass / proxypassreverse / </virtualhost> where IIS would run on port 3000. regards - Hide quoted text -- Show quoted text - So, after all, not was windows the easy and linux the ugly! The first option... that not mean that a URL become:? Is fine for development or in-house websites but I'm planing run comercial websites... IIS would need to forward the request to the port and then push the response back to you something like this is what I am talking about On 24/05/2006, at 8:38 AM, mamc...@gmail.com wrote: > I don't think the last option (swap the IIS for Apache) like to the > hosting company. Remember: is a shared hosting server, already RUNNING > websites and that thing (the test part is my job, but if that pass ok > this must be a simply thing for theirs)... > The first option... that not mean that a URL become: >? > Is fine for development or in-house websites but I'm planing run > comercial websites... greetings, Giorgi And I think is very confusing. Is not starnge then people fear to test python for web hosting: is far more dificult that any other web-enable language in the deploy side of the things... I read the ActiveState site: Don't say anything. The PyISAPI project not have anything about how configure the thing The only thing I can figure is (for FastCGI)... About install ruby on IIS.. have some sense, but only have in return blank pages... I check the WSGI support and maybe I can figure something but the requeriment to build a .asp page for EACH Url is insane... and the thing about replicate the url rewriting is not fun... I only found people that say was able to use IIS with fastcgi or that say WSGI is the way for python but nothing concrete yet... I have the option to get Linux as a fallback. The reason? I have everything now under this package, the databases, the sites, the expertise. I have almost zero experience in run linux and configure this... Anyway, despite the fact if I go to Linux or not, I think that persue the option of easy to run under IIS can help python/django in the exposure side of the things... Take in account that if something is under IIS is because run also ASP/ASP.NET and have some investiment here... Add another web server is hard to sell... > I know... > I have the option to get Linux as a fallback. Thanks, Brett. I've done it. It works fine. And then I woke up and installed Apache and turned off the IIS service. Note that if you are stuck on Windows, Apache + mod_python + MySQL + Django works very well. I run that at work and do a lot of my personal Django development on that and then just "svn up" and "service httpd restart" on my Linux box to roll out changes. > I've used Python with IIS for the MoinMoin wiki (where do they get > these names?). On 26/05/2006, at 7:15 AM, Jeremy Dunck wrote: >> Note that if you are stuck on Windows, Apache + mod_python + MySQL + >> Django works very well. > Doesn't pre-forking apache on windows scale badly due to window's high > process startup cost? I guess it'd depend how often you recycle your > httpd processes... That is YOUR experience. My web server never have that kind of troubles. I have my small developer company with Windows 2003 and I expose my svn, and other 3/4 internal websites. I don't have problems with viruses or hacking and run well all this time. I know that windows by default can be more insecure. But that is not my experience and that is not the point. The point is: Is possible run well django/python under IIS, yes or not? I don't know why the rude acctitude... I'm a former Windows Developer for 7 years and found a compelling reason to try python and put it for my company. I'm risking because a)My experience in python is 1 month 2)My experience in django is 2 weeks? I'm triying to lowe the risk. And if is not possible, I'm willing to try linux... For this hosting setup, I don't have problems in the security or performance arena... but maybe because is the main plataform for python/django? I'm more worry about crash or glacial performance. I used to be a C#/ASP.NET guy so I have used IIS quite a bit. Its not bad, and I haven't had the problems with security that other note - at least not in any of the more recent versions of Windows and IIS. But I just find for the development platform I've chose, Apache is a better fit than IIS. That's all.... :( I look to the rails guys how install ruby on rails under IIS. I get this: And with I was able to get close... I install FastCGI for windows and configure the fcgi file this way: from flup.server.fcgi_fork import WSGIServer #from flup.server.fcgi import WSGIServer from flup.middleware.gzip import GzipMiddleware from django.core.handlers.wsgi import WSGIHandler sys.path.insert(0, 'E:\\Proyectos\\Python\\jhonWeb\\') os.environ['DJANGO_SETTINGS_MODULE'] = 'jhonWeb.settings' handler = WSGIHandler() handler = GzipMiddleware(handler) WSGIServer(handler).run() I try to the default way in django site I setup the urlrewrite like this: <?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section name="rewriter" type="Intelligencia.UrlRewriter.Configuration.RewriterConfigurationSectionH andler, Intelligencia.UrlRewriter" /> </configSections> <rewriter> <if url="^(/[^.]+)$" rewrite="jhonWeb.fcgi?$1" /> </rewriter> <system.web> <httpModules> <add type="Intelligencia.UrlRewriter.RewriterHttpModule,Intelligencia.UrlRewrite r" name="UrlRewriter" /> </httpModules> </system.web> </configuration> And I get: The virtual path '/jhonWeb.fcgi' maps to another application, which is not allowed I allow the fastcgi.dll for .fcgi files and configure the registry. I follow the steps of the ruby on rails info I point before. It's really easy to get going - if you download the newest version () you'll see the adapter with the example Python code. I did some performance testing with a few different apps included in Django (I think it was an admin page and one of the hello apps) - I was getting between 900 and 1700 requests per second. Hope that's good enough for you ;) I'm glad I was able to bring the two together so easily, considering that my focus on the ISAPI part of the project has been so narrow that I have yet to add tools similar to what Django already has. Please let me know if you have questions, and enjoy! - Phillip >... > :(	http://groups.google.com/group/django-users/browse_thread/thread/530e823938919feb	crawl-002	refinedweb	1,316	66.94

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