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• Getting started with open source

  - by lola

  Hi all, I'm an undergraduate who has decided that he wants to join the open source community and contribute. However, I have come to think that, once you have chosen an open source project, a lot of time is spent in learning the nitty gritties of that project in addition to stuff like subversion,etc which a typical undergraduate isn't exposed to. So, you have to stick with that project for a long time, say a year or two, before moving on to other projects. In this case, choosing the right(for you) initial project is very important since if you choose one,and say, the development in your field of interest(in that project) is a low priority and not exciting enough, you'll lose interest and stop contributing to open source all together. So what I wanted to know was, since there are thousands of open source projects, is all this being documented somewhere with tags,etc so that a beginner can choose his projects. The GSoc 2010 ideas list is a great starting point, but it only covers a handful. Hence, I thought why not ask this at stackoverflow: if you have any pointers as to where to start, when choosing a FOSS project or any other tips related to starting with FOSS. P.S. I'm interested in projects involving mobile ad hoc networks(those using TinyOS, preferably), so pointers related to these will be great. I'm looking through Freifunk and OLPC as of now, needed more ideas.

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• SQLAlchemy: who is in charge of the "session"? ( and how to unit-test with sessions )

  - by Nick Perkins

  I need some guidance on how to use session objects with SQLAlchemy, and how to organize Unit Tests of my mapped objects. What I would like to able to do is something like this: thing = BigThing() # mapped object child = thing.new_child() # create and return a related object thing.save() # will also save the child object In order to achieve this, I was thinking of having the BigThing actually add itself ( and it's children ) to the database -- but maybe this not a good idea? One reason to add objects as soon as possible is Automatic id values that are assigned by the database -- the sooner they are available, the fewer problems there are ( right? ) What is the best way to manage session objects? Who is in charge of the session? Should it be created only when required? or saved for a long time? What about Unit Tests for my mapped objects?...how should the session be handled? Is it ever OK to have mapped objects just automatically add themselves to a database? or is that going to lead to trouble?

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• capturing CMD batch file parameter list; write to file for later processing

  - by BobB

  I have written a batch file that is launched as a post processing utility by a program. The batch file reads ~24 parameters supplied by the calling program, stores them into variables, and then writes them to various text files. Since the max input variable in CMD is %9, it's necessary to use the 'shift' command to repeatedly read and store these individually to named variables. Because the program outputs several similar batch files, the result is opening several CMD windows sequentially, assigning variables and writing data files. This ties up the calling program for too long. It occurs to me that I could free up the calling program much faster if maybe there's a way to write a very simple batch file that can write all the command parameters to a text file, where I can process them later. Basically, just grab the parameter list, write it and done. Q: Is there some way to treat an entire series of parameter data as one big text string and write it to one big variable... and then echo the whole big thing to one text file? Then later read the string into %n variables when there's no program waiting to resume? Parameter list is something like 25 - 30 words, less than 200 characters. Sample parameter list: "First Name" "Lastname" "123 Steet Name Way" "Cityname" ST 12345 1004968 06/01/2010 "Firstname+Lastname" 101738 "On Account" 20.67 xy-1z 1 8.95 3.00 1.39 0 0 239 8.95 Items in quotes are processed as string variables. List is space delimited. Any suggestions?

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• How would I find all sets of N single-digit, non-repeating numbers that add up to a given sum in PHP

  - by TerranRich

  Let's say I want to find all sets of 5 single-digit, non-repeating numbers that add up to 30... I'd end up with [9,8,7,5,1], [9,8,7,4,2], [9,8,6,4,3], [9,8,6,5,2], [9,7,6,5,3], and [8,7,6,5,4]. Each of those sets contains 5 non-repeating digits that add up to 30, the given sum. Any help would be greatly appreciated. Even just a starting point for me to use would be awesome. I came up with one method, which seems like a long way of going about it: get all unique 5-digit numbers (12345, 12346, 12347, etc.), add up the digits, and see if it equals the given sum (e.g. 30). If it does, add it to the list of possible matching sets. I'm doing this for a personal project, which will help me in solving Kakuro puzzles without actually solving the whole thing at once. Yeah, it may be cheating, but it's... it's not THAT bad... :P

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• Logic for family tree program

  - by david robers

  Hi All, I am creating a family tree program in Java, or at least trying to. I have developed several classes: Person - getters and setter for name gender age etc FamilyMember - extends Person getters and setters for setting arents and children Family - which consists of multiple family members and methods for adding removing members FamilyTree which is the main class for setting relationships. I have two main problems: 1) I need to set the relationships between people. Currently I am doing: FamilyMember A, FamilyMember B B.setMother(A); A.setChild(B); The example above is for setting a mother child relationship. This seems very clunky. Its getting very long winded to implement all relationships. Any ideas on how to implement multiple relationships in a less prodcedural way? 2) I have to be able to display the family tree. How can I do this? Are there any custom classes out there to make life easier? Thanks for your time...

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• radio input replacement using jquery

  - by altvali

  It may seem a bit odd to ask this since there are several solutions out there but the fact is that all of them look pretty and none of what i've seem save the input value for form submission the right way. I'm looking for something that will replace all radio inputs with divs that get special classes when they are hovered or clicked, and an input type hidden for every group of radio inputs with the same name, hidden input that will be updated with the value corresponding to the div the user clicks on. Long sentence, i know. Here's what i've come up with: $('input:radio').each(function(){ if (this.style.display!='none') { var inputName = $(this).attr('name'); var inputValue = $(this).attr('value'); var isChecked = $(this).attr('checked'); if (!$('input:hidden[name='+inputName+']').length) // if the hidden input wasn't already created $(this).replaceWith('<div class="inputRadioButton" id="'+inputName+'X'+inputValue+'"></div><input type="hidden" name="'+inputName+'" value="'+inputValue+'" />'); else{ $(this).replaceWith('<div class="inputRadioButton" id="'+inputName+'X'+inputValue+'"></div>'); if (isChecked) $('input:hidden[name='+inputName+']').attr({'value':inputValue}); } //this bind doesn't work $("#"+inputName+"X"+inputValue).click(function(){ if($('input:hidden[name='+inputName+']').val()!=inputValue){ $('input:hidden[name='+inputName+']').attr({'value':inputValue}); $('div[id*='+inputName+'].inputRadioButton').removeClass('inputRadioButtonSelected'); } if (!$("#"+inputName+"X"+inputValue).hasClass('inputRadioButtonSelected')) $("#"+inputName+"X"+inputValue).addClass('inputRadioButtonSelected'); }); } }); Please tell me how to fix it. Thank you. Edit I've found the reason. It should normally work but some of my radio inputs generated by an e-commerce software had brackets in them (e.g. id[12] ) and jQuery was parsing that. The fix is adding var inputButton = document.getElementById(inputName+"X"+inputValue); before the bind and replacing $("#"+inputName+"X"+inputValue) with $(inputButton).

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• Components don't show in custom JPanel/JComponent

  - by Bart van Heukelom

  I've created a custom swing component. I can see it (the grid from the paint method is drawn), but the buttons that are added (verified by println) aren't shown. What am I doing wrong? Background information: I'm trying to build a tree of visible objects like the Flash/AS3 display list. public class MapPanel extends JComponent { // or extends JPanel, same effect private static final long serialVersionUID = 4844990579260312742L; public MapPanel(ShapeMap map) { setBackground(Color.LIGHT_GRAY); setPreferredSize(new Dimension(1000,1000)); setLayout(null); for (Layer l : map.getLayers()) { // LayerView layerView = new LayerView(l); // add(layerView); System.out.println(l); JButton test = new JButton(l.getName()); add(test); validate(); } } @Override protected void paintComponent(Graphics g) { // necessary? super.paintComponent(g); // background g.setColor(getBackground()); g.fillRect(0, 0, getWidth(), getHeight()); // grid g.setColor(Color.GRAY); for (double x = 0; x < getWidth(); x += 10) { g.drawLine((int)x, 0, (int)x, getHeight()); } for (double y = 0; y < getHeight(); y += 10) { g.drawLine(0, (int)y, getWidth(), (int)y); } } }

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• Should I use IDisposable for purely managed resources?

  - by John Gietzen

  Here is the scenario: I have an object called a Transaction that needs to make sure that only one entity has permission to edit it at any given time. In order to facilitate a long-lived lock, I have the class generating a token object that can be used to make the edits. You would use it like this: var transaction = new Transaction(); using (var tlock = transaction.Lock()) { transaction.Update(data, tlock); } Now, I want the TransactionLock class to implement IDisposable so that its usage can be clear. But, I don't have any unmanaged resources to dispose. however, the TransctionLock object itself is a sort of "unmanaged resource" in the sense that the CLR doesn't know how to properly finalize it. All of this would be fine and dandy, I would just use IDisposable and be done with it. However, my issue comes when I try to do this in the finalizer: ~TransactionLock() { this.Dispose(false); } I want the finalizer to release the transaction from the lock, if possible. How, in the finalizer, do I detect if the parent transaction (this.transaction) has already been finalized? Is there a better pattern I should be using? The Transaction class looks something like this: public sealed class Transaction { private readonly object lockMutex = new object(); private TransactionLock currentLock; public TransactionLock Lock() { lock (this.lockMutex) { if (this.currentLock != null) throw new InvalidOperationException(/* ... */); this.currentLock = new TransactionLock(this); return this.currentLock; } } public void Update(object data, TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); // ... } } internal void ValidateLock(TransactionLock tlock) { if (this.currentLock == null) throw new InvalidOperationException(/* ... */); if (this.currentLock != tlock) throw new InvalidOperationException(/* ... */); } internal void Unlock(TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); this.currentLock = null; } } }

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• How to Inject code in c# method calls from a separate app

  - by Fusspawn

  I was curious if anyone knew of a way of monitoring a .Net application's runtime info (what method is being called and such) and injecting extra code to be run on certain methods from a separate running process. say i have two applications: app1.exe that for simplicity's sake could be class Program { static void Main(string[] args) { while(true){ Somefunc(); } } static void Somefunc() { Console.WriteLine("Hello World"); } } and I have a second application that I wish to be able to detect when Somefunc() from application 1 is running and inject its own code, class Program { static void Main(string[] args) { while(true){ if(App1.SomeFuncIsCalled) InjectCode(); } } static void InjectCode() { App1.Console.WriteLine("Hello World Injected"); } } So The result would be Application one would show Hello World Hello World Injected I understand its not going to be this simple ( By a long shot ) but I have no idea if it's even possible and if it is where to even start. Any suggestions ? I've seen similar done in java, But never in c#. EDIT: To clarify, the usage of this would be to add a plugin system to a .Net based game that I do not have access to the source code of.

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• MouseMotion Sensor Method Call

  - by user321894

  I have a soon-to-be due assignment due in computer science. I have encountered a problem, for which no matter how long I study the API's of the class and superclasses, I can not figure out. Suppose I wish to design a sort of "Breakout game" where the mouse motion controls the motion of a block that is used to bounce a ball, which then destroys multi colored bricks. How do you specifically make the block "listen" to the mouse? The below code is what I have attempted to achieve the desired results. /** Breakout Program*/ public class Breakout extends GraphicsProgram implements MouseMotionListener { ... /** The Paddle Itself */ private GRect paddle = new GRect(0, HEIGHT-PADDLEBOTTOM_OFFSET, PADDLEWIDTH, PADDLEHEIGHT); ... /** Run the Breakout program. */ public void run() { paddle.setFillColor(Color.BLACK); paddle.setFilled(true); add(paddle); paddle.addMouseListener(this); ... } /** Move the horizontal middle of the paddle to the x-coordinate of the mouse position - * -but keep the paddle completely on the board. */ public void mouseMoved(MouseEvent e) { GPoint p= new GPoint(e.getPoint()); double x = p.getX(); paddle.setLocation(x, HEIGHT-PADDLEBOTTOM_OFFSET); } } Any clarification on why/what I am doing incorrectly would be helpful, thanks.

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• curl_multi_exec stops if one url is 404, how can I change that?

  - by Rob

  Currently, my cURL multi exec stops if one url it connects to doesn't work, so a few questions: 1: Why does it stop? That doesn't make sense to me. 2: How can I make it continue? EDIT: Here is my code: $SQL = mysql_query("SELECT url FROM shells") ; $mh = curl_multi_init(); $handles = array(); while($resultSet = mysql_fetch_array($SQL)){ //load the urls and send GET data $ch = curl_init($resultSet['url'] . $fullcurl); //Only load it for two seconds (Long enough to send the data) curl_setopt($ch, CURLOPT_TIMEOUT, 5); curl_multi_add_handle($mh, $ch); $handles[] = $ch; } // Create a status variable so we know when exec is done. $running = null; //execute the handles do { // Call exec. This call is non-blocking, meaning it works in the background. curl_multi_exec($mh,$running); // Sleep while it's executing. You could do other work here, if you have any. sleep(2); // Keep going until it's done. } while ($running > 0); // For loop to remove (close) the regular handles. foreach($handles as $ch) { // Remove the current array handle. curl_multi_remove_handle($mh, $ch); } // Close the multi handle curl_multi_close($mh);

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• How to approach parallel processing of messages?

  - by Dan

  I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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• How to view shell commands used by eclipse "run configurations"

  - by gmale

  Given a "run configuration" in Eclipse, I want to print out the associated shell command that would be used to run it. For example: Right now, in Eclipse, if I click "play" it will run: mvn assembly:directory -Dmaven.test.skip=true I don't see that command, I just know that's what the IDE must run, at some point. However, some of the other run configurations are far more complex with long classpaths and virtual machine options and, frankly, sometimes I have no idea what the equivalent shell command would be (particularly when it comes to Flex). There must be some way to access the shell command that would be associated with a "Run Configuration" in Eclipse/Flex Builder. This information must be available, which leads me to believe someone has written a plugin to display it. Or maybe there's already an option built into Eclipse for accessing this. So is there a way to, essentially, convert an Eclipse run configuration into a shell command? (for context only: I'm asking because I'm writing a bash script that automates everything I do, during development--from populating the Database all the way to opening Firefox and clearing the cache before running the web app. So every command I run from the IDE needs to exist in the script. Some are tricky to figure out.)

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• convert htmlelement to string for comparison javascript

  - by Jamex

  Hi, I am using a function that obtains a target element id at onclick. Example, if I click on the text element that has the id of 'help'. var click = (e && e.target) || (event && event.srcElement); The var click would contain the ref to the id of "help". I want to compare the var click to the string 'help' using the if statement below. if (click == 'about') {do something} The comparison does not work because the var click is not a string. When I use the alert(click) to debug, it shows click as "object HTMLElement". How would you compare whether the id 'help' is obtained from var click? I could write out something like if (click == document.getElementById('help')) {do something} but that would make a long statement. also if the var click is document.getElementById('help'), how would you make a new var "show" as document.getElementById('showhelp') basically, I want to use the same function to generate dynamic responses to each element that was clicked on, and not having to create a separate function for each element.

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• Java Script in Rails 3.1 works only in certain parts. Any idea why?

  - by Sergio Nekora

  This might seem a bit weird, but since I am new in RoR and cannot find any similar questions I thought you might know. The situation is that JavaScript does not work throughout my whole site. For instance. For the sake of checking, I place a link with an alert function in the footer. It did not work at the beginning, it felt like the JS was disabled(but it wasn't). But eventually it worked. Now it works in most the pages but it does not work in one that there is also an 'autocomplete' field. Of course, this autocomplete field does not work either. That could lead you to think that there is something wrong with the autocomplete code. However this same code is working in the sidebar. Any ideas why? Could it have anything to do with the fact that one day my assets folder appeared empty? After installing the gmaps4rails gem I realized that all my Js and CSS files were gone from my assests folder. Ok, it might have happened long before and I just realized at that point. I don't really know. Here in the root you can see that the 'Hola sip' click at the button works. here it works However, here same link does not trigger the alert function. here it doesn't

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• Web service performing asynchronous call

  - by kornelijepetak

  I have a webservice method FetchNumber() that fetches a number from a database and then returns it to the caller. But just before it returns the number to the caller, it needs to send this number to another service so instantiates and runs the BackgroundWorker whose job is to send this number to another service. public class FetchingNumberService : System.Web.Services.WebService { [WebMethod] public int FetchNumber() { int value = Database.GetNumber(); AsyncUpdateNumber async = new AsyncUpdateNumber(value); return value; } } public class AsyncUpdateNumber { public AsyncUpdateNumber(int number) { sendingNumber = number; worker = new BackgroundWorker(); worker.DoWork += asynchronousCall; worker.RunWorkerAsync(); } private void asynchronousCall(object sender, DoWorkEventArgs e) { // Sending a number to a service (which is Synchronous) here } private int sendingNumber; private BackgroundWorker worker; } I don't want to block the web service (FetchNumber()) while sending this number to another service, because it can take a long time and the caller does not care about sending the number to another service. Caller expects this to return as soon as possible. FetchNumber() makes the background worker and runs it, then finishes (while worker is running in the background thread). I don't need any progress report or return value from the background worker. It's more of a fire-and-forget concept. My question is this. Since the web service object is instantiated per method call, what happens when the called method (FetchNumber() in this case) is finished, while the background worker it instatiated and ran is still running? What happens to the background thread? When does GC collect the service object? Does this prevent the background thread from executing correctly to the end? Are there any other side-effects on the background thread? Thanks for any input.

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• real time stock quotes, StreamReader performance optimization

  - by sean717

  I am working on a program that extracts real time quote for 900+ stocks from a website. I use HttpWebRequest to send HTTP request to the site and store the response to a stream and open a stream using the following code: HttpWebResponse response = (HttpWebResponse)request.GetResponse(); Stream stream = response.GetResponseStream (); StreamReader reader = new StreamReader( stream ) the size of the received HTML is large (5000+ lines), so it takes a long time to parse it and extract the price. For 900 files, It takes about 6 mins for parsing and extracting. Which my boss isn't happy with, he told me he'd want the whole process to be done in TWO mins. I've identified the part of the program that takes most of time to finish is parsing and extracting. I've tried to optimize the code to make it faster, the following is what I have now after some optimization: // skip lines at the top for(int i=0;i<1500;++i) reader.ReadLine(); // read the line that contains the price string theLine = reader.ReadLine(); // ... extract the price from the line now it takes about 4 mins to process all the files, there is still a significant gap to what my boss's expecting. So I am wondering, is there other way that I can further speed up the parsing and extracting and have everything done within 2 mins?

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• VS 2008 C++ build output?

  - by STingRaySC

  Why when I watch the build output from a VC++ project in VS do I see: 1Compiling... 1a.cpp 1b.cpp 1c.cpp 1d.cpp 1e.cpp [etc...] 1Generating code... 1x.cpp 1y.cpp [etc...] The output looks as though several compilation units are being handled before any code is generated. Is this really going on? I'm trying to improve build times, and by using pre-compiled headers, I've gotten great speedups for each ".cpp" file, but there is a relatively long pause during the "Generating Code..." message. I do not have "Whole Program Optimization" nor "Link Time Code Generation" turned on. If this is the case, then why? Why doesn't VC++ compile each ".cpp" individually (which would include the code generation phase)? If this isn't just an illusion of the output, is there cross-compilation-unit optimization potentially going on here? There don't appear to be any compiler options to control that behavior (I know about WPO and LTCG, as mentioned above). EDIT: The build log just shows the ".obj" files in the output directory, one per line. There is no indication of "Compiling..." vs. "Generating code..." steps. EDIT: I have confirmed that this behavior has nothing to do with the "maximum number of parallel project builds" setting in Tools - Options - Projects and Solutions - Build and Run. Nor is it related to the MSBuild project build output verbosity setting. Indeed if I cancel the build before the "Generating code..." step, the ".obj" files will not exist for the most recent set of "compiled" files. E.g., if I cancel the build during "c.cpp" above, I will see only "a.obj" and "b.obj".

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• Passing a parameter in a Report's Open Event to a parameter query (Access 2007)

  - by JPM

  Hi there, I would like to know if there is a way to set the parameters in an Access 2007 query using VBA. I am new to using VBA in Access, and I have been tasked with adding a little piece of functionality to an existing app. The issue I am having is that the same report can be called in two different places in the application. The first being on a command button on a data entry form, the other from a switchboard button. The report itself is based on a parameter query that has requires the user to enter a Supplier ID. The user would like to not have to enter the Supplier ID on the data entry form (since the form displays the Supplier ID already), but from the switchboard, they would like to be prompted to enter a Supplier ID. Where I am stuck is how to call the report's query (in the report's open event) and pass the SupplierID from the form as the parameter. I have been trying for a while, and I can't get anything to work correctly. Here is my code so far, but I am obviously stumped. Private Sub Report_Open(Cancel As Integer) Dim intSupplierCode As Integer 'Check to see if the data entry form is open If CurrentProject.AllForms("frmExample").IsLoaded = True Then 'Retrieve the SupplierID from the data entry form intSupplierCode = Forms![frmExample]![SupplierID] 'Call the parameter query passing the SupplierID???? DoCmd.OpenQuery "qryParams" Else 'Execute the parameter query as normal DoCmd.OpenQuery "qryParams"????? End If End Sub I've tried Me.SupplierID = intSupplierCode, and although it compiles, it bombs when I run it. And here is my SQL code for the parameter query: PARAMETERS [Enter Supplier] Long; SELECT Suppliers.SupplierID, Suppliers.CompanyName, Suppliers.ContactName, Suppliers.ContactTitle FROM Suppliers WHERE (((Suppliers.SupplierID)=[Enter Supplier])); I know there are ways around this problem (and probably an easy way as well) but like I said, my lack of experience using Access and VBA makes things difficult. If any of you could help, that would be great!

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• PHP Socket Server vs node.js: Web Chat

  - by Eliasdx

  I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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• How can you transform a set of numbers into mostly whole ones?

  - by Alice

  Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

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• How to benchmark on multi-core processors

  - by Pascal Cuoq

  I am looking for ways to perform micro-benchmarks on multi-core processors. Context: At about the same time desktop processors introduced out-of-order execution that made performance hard to predict, they, perhaps not coincidentally, also introduced special instructions to get very precise timings. Example of these instructions are rdtsc on x86 and rftb on PowerPC. These instructions gave timings that were more precise than could ever be allowed by a system call, allowed programmers to micro-benchmark their hearts out, for better or for worse. On a yet more modern processor with several cores, some of which sleep some of the time, the counters are not synchronized between cores. We are told that rdtsc is no longer safe to use for benchmarking, but I must have been dozing off when we were explained the alternative solutions. Question: Some systems may save and restore the performance counter and provide an API call to read the proper sum. If you know what this call is for any operating system, please let us know in an answer. Some systems may allow to turn off cores, leaving only one running. I know Mac OS X Leopard does when the right Preference Pane is installed from the Developers Tools. Do you think that this make rdtsc safe to use again? More context: Please assume I know what I am doing when trying to do a micro-benchmark. If you are of the opinion that if an optimization's gains cannot be measured by timing the whole application, it's not worth optimizing, I agree with you, but I cannot time the whole application until the alternative data structure is finished, which will take a long time. In fact, if the micro-benchmark were not promising, I could decide to give up on the implementation now; I need figures to provide in a publication whose deadline I have no control over.

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• program won't find math.h anymore

  - by 130490868091234

  After a long time, I downloaded a program I co-developed and tried to recompile it on my Ubuntu Linux 12.04, but it seems it does not find math.h anymore. This may be because something has changed recently in gcc, but I can't figure out if it's something wrong in src/Makefile.am or a missing dependency: Download from http://www.ub.edu/softevol/variscan/: tar xzf variscan-2.0.2.tar.gz cd variscan-2.0.2/ make distclean sh ./autogen.sh make I get: [...] gcc -DNDEBUG -O3 -W -Wall -ansi -pedantic -lm -o variscan variscan.o statistics.o common.o linefile.o memalloc.o dlist.o errabort.o dystring.o intExp.o kxTok.o pop.o window.o free.o output.o readphylip.o readaxt.o readmga.o readmaf.o readhapmap.o readxmfa.o readmav.o ran1.o swcolumn.o swnet.o swpoly.o swref.o statistics.o: In function `calculate_Fu_and_Li_D': statistics.c:(.text+0x497): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F': statistics.c:(.text+0x569): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_D_star': statistics.c:(.text+0x63b): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F_star': statistics.c:(.text+0x75c): undefined reference to `sqrt' statistics.o: In function `calculate_Tajima_D': statistics.c:(.text+0x85d): undefined reference to `sqrt' statistics.o:statistics.c:(.text+0xcb1): more undefined references to `sqrt' follow statistics.o: In function `calcRunMode21Stats': statistics.c:(.text+0xe02): undefined reference to `log' statistics.o: In function `correctedDivergence': statistics.c:(.text+0xe5a): undefined reference to `log' statistics.o: In function `calcRunMode22Stats': statistics.c:(.text+0x104a): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_fs': statistics.c:(.text+0x11a8): undefined reference to `fabsl' statistics.c:(.text+0x11ca): undefined reference to `powl' statistics.c:(.text+0x11f2): undefined reference to `logl' statistics.o: In function `calculateStatistics': statistics.c:(.text+0x13f2): undefined reference to `log' collect2: ld returned 1 exit status make[1]: *** [variscan] Error 1 make[1]: Leaving directory `/home/avilella/variscan/latest/variscan-2.0.2/src' make: *** [all-recursive] Error 1 The libraries are there because this simple example works perfectly well: $ gcc test.c -o test -lm $ cat test.c #include <stdio.h> #include <math.h> int main(void) { double x = 0.5; double result = sqrt(x); printf("The hyperbolic cosine of %lf is %lf\n", x, result); return 0; } Any ideas?

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• loading google maps drawing manager object

  - by psychok7

  So i am using Google Maps Drawing Manager to draw some polygons and i am saving the lat e long coordinates to my database. Now my question is, after i load that to my array, how can i rebuild the saved polygon back into my map? I can't seem to find a code to understand that. this is what i have now : window.initialize_2 = function () { var mapOptions = { center: new google.maps.LatLng(-34.397, 150.644), zoom: 8, mapTypeId: google.maps.MapTypeId.ROADMAP }; var map = maplimits; var drawingManager = new google.maps.drawing.DrawingManager({ drawingMode: google.maps.drawing.OverlayType.MARKER, drawingControl: true, drawingControlOptions: { position: google.maps.ControlPosition.TOP_CENTER, drawingModes: [ google.maps.drawing.OverlayType.POLYGON] }, markerOptions: { icon: 'images/beachflag.png' }, polygonOptions: { fillColor: '#ffff00', fillOpacity: 10, strokeWeight: 5, clickable: true, editable: true, zIndex: 1 } }); var coord_listener = google.maps.event.addListener(drawingManager, 'polygoncomplete', function (polygon) { var coordinates = (polygon.getPath().getArray()); console.log(coordinates); window.poly = polygon; }); //delete shape google.maps.event.addListener(drawingManager, 'overlaycomplete', function (e) { if (e.type != google.maps.drawing.OverlayType.MARKER) { // Switch back to non-drawing mode after drawing a shape. drawingManager.setDrawingMode(null); // Add an event listener that selects the newly-drawn shape when the user // mouses down on it. var newShape = e.overlay; newShape.type = e.type; google.maps.event.addListener(newShape, 'click', function () { setSelection(newShape); }); setSelection(newShape); } }); // Clear the current selection when the drawing mode is changed, or when the // map is clicked. google.maps.event.addListener(drawingManager, 'drawingmode_changed', clearSelection); google.maps.event.addListener(map, 'click', clearSelection); drawingManager.setMap(map); }

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• Regular expression to match HTML table row ( <tr> ) NOT containing a specific value

  - by user1821136

  I'm using Notepad++ to clean up a long and messy HTML table. I'm trying to use regular expressions even if I'm a total noob. :) I need to remove all the table rows that doesn't contain a specific value (may I call that substring?). After having all the file contents unwrapped, I've been able to use the following regular expression to select, one by one, every table row with all its contents: <tr>.+?</tr> How can I improve the regular expression in order to select and replace only table rows containing, somewhere inside a part of them, that defined substring? I don't know if this does matter but the structure of every table row is the following (I've put there every HTML tag, the dots stand for standard content/values) <tr> <td> ... </td> <td> ... </td> <td> <a sfref="..." href="...">!! SUBSTRING I HAVE TO MATCH HERE !!</a> </td> <td> <img /> </td> <td> ... </td> <td> ... </td> <td> ... </td> <td> ... </td> </tr> Thanks in advance for your help!

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