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  • Print Preview Control used in a custom Print Preview Dialog.

    - by Kildareflare
    I have successfully implemented printing and print preview for my app using the PrintDocument, PrintDialog and PrintPreviewDialog classes of .NET. However my app uses a toolkit to improve the appearance of the standard .NET controls. There are versions of most .NET controls in the toolkit, but none for the Print controls. Therefore to ensure that the appearance of these controls matches the rest of the app I am creating a custom PrintPreviewDialog based on a toolkit form and embedding a .NET PrintPrewviewControl in it. My problem is that the PrintPreviewControl always shows "No pages to display". I had no trouble getting this to work using the .NET PrintPreviewDialog and cannot see what I am doing wrong. This is a .NET 2.0 PrintPreviewControl and so I know that I need to call InvalidatePreview() after assigning the PrintDocument. However it does not seem to matter where i place it, the PrintPage event handler never gets called... EDIT: I've just noticed that while the original PrintDocument m_printDocument shows a PrintPageHandler in its properties, the m_printPreviewControl.Document does not. Any ideas why it is being lost..? public class PrintEngine { ...rest of class... public PrintEngine() { m_printDoc.PrintPage += new PrintPageEventHandler(printDoc_PrintPage); } public void PrintPreview() { //ORIGINAL CODE USING .NET DIALOG WORK OK //PrintPreviewDialog dlg1 = new PrintPreviewDialog(); //dlg1.Document = m_printDoc; //PrepareImageForPrinting(); //dlg1.ShowDialog(); //CODE USING MY CUSTOM DIALOG DO NOT WORK? MyPrintPreviewDialog dlg2 = new MyPrintPreviewDialog(); dlg2.Document = m_printDoc; PrepareImageForPrinting(); //Creates the m_printImage List dlg2.ShowDialog(); } private void printDoc_PrintPage(object sender, PrintPageEventArgs e) { e.Graphics.DrawImage(m_printImages[m_currentPage], new Point(0, 0)); m_currentPage++; e.HasMorePages = m_currentPage < m_pagesHigh; } }//end PrintEngine class public class MyPrintPreviewDialog : KryptonForm { public PrintDocument Document { get { return m_printPreviewControl.Document; } set { m_printPreviewControl.Document = value; m_printPreviewControl.InvalidatePreview(); } } public MyPrintPreviewDialog() { InitializeComponent(); m_printPreviewControl = new PrintPreviewControl(); m_printPreviewControl.StartPage = 0; } private void MyPrintPreviewDialog_Load(object sender, EventArgs e) { m_printPreviewControl.Document.DefaultPageSettings = new PageSettings(); m_printPreviewControl.Document.PrinterSettings = new PrinterSettings(); m_printPreviewControl.InvalidatePreview(); } }//end MyPrintPreviewDialog class

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  • SerialPort ReadLine() after Thread.Sleep() goes crazy

    - by Mat
    Hi everybody, I've been fighting with this issue for a day and I can't find answer for it. I am trying to read data from GPS device trough COM port in Compact Framework C#. I am using SerialPort class (actually my own ComPort class boxing SerialPort, but it adds only two fields I need, nothing special). Anyway.. I am running while loop in a separate thread which reads line from the port, analyze NMEA data, print them, catch all exceptions and then I Sleep(200) the thread, cause I need CPU for other threads... Without Sleep it works fine, but uses 100% CPU.. When I dont use Sleep after few minutes the output from COM port looks like this: GPGSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F GSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F A,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,18,12,271,24,24,05,020,24,14,04,326,25,11,03,023,*76 A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F as you can see the same message is read few times but cut. I wonder what I'm doing wrong... My port configuration: port.ReadBufferSize = 4096; port.BaudRate = 4800; port.DataBits = 8; port.Parity = Parity.None; port.StopBits = StopBits.One; port.NewLine = "\r\n"; port.ReadTimeout = 1000; port.ReceivedBytesThreshold = 100000; And my reading function: private void processGps(){ while (!closing) { //reconnect if needed try { string sentence = port.ReadLine(); //here print the sentence //analyze the sentence (this takes some time 50-100ms) } catch (TimeoutException) { Thread.Sleep(0); } catch (IOException ioex) { //handling IO exception (some info on the screen) } Thread.Sleep(200); } } There is some more stuff in this function like reconnection if the device is lost etc.. but it is not called when the GPS is connected properly.. I was trying port.DiscardInBuffer(); after some blocks of code (in TimeoutException, after read..) Did anyone had similar problem? I really dont know what I'm doing wrong.. The only way to get rig of it is removing the last Sleep... Thanks in advance! Best Regards, Mat

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  • Using FFmpeg in .net?

    - by daniel
    So i know its a fairly big challenge but i want to write a basic movie player/converter in c# using the FFmpeg library. However the first obstacle i need to overcome is wrapping the FFmpeg library in c#. I downloaded ffmpeg but couldn't compile it on windows, so i downloaded a precompiled version for me. Ok awesome. Then i started looking for c# wrappers. I have looked around and have found a few wrappers such as SharpFFmpeg (http://sourceforge.net/projects/sharpffmpeg/) and ffmpeg-sharp (http://code.google.com/p/ffmpeg-sharp/). First of all i wanted to use ffmpeg-sharp as its LGPL and SharpFFmpeg is GPL. However it had quite a few compile errors. Turns out it was written for the mono compiler, i tried compiling it with mon but couldn't figure out how. I then started to manually fix the compiler errors myself, but came across a few scary ones and thought i'd better leave those alone. So i gave up on ffmpeg-sharp. Then i looked at SharpFFmpeg and it looks like what i want, all the functions P/Invoked for me. However its GPL? Both the AVCodec.cs and AVFormat.cs files look like ports of avcodec.c and avformat.c which i reckon i could port myself? Then not have to worry about licencing. But i wan't to get this right before i go ahead and start coding. Should I: Write my own c++ library for interacting with ffmpeg, then have my c# program talk to the c++ library in order to play/convert videos etc. OR Port avcodec.h and avformat.h (is that all i need?) to c# by using a whole lot of DllImports and write it entirely in c#? First of all consider that i'm not great at c++ as i rarely use it but i know enough to get around. The reason i'm thinking #1 might be the better option is that most FFmpeg tutorials are in c++ and i'd also have more control over memory management than if i was to do it in c#. What do you think? Also would you happen to have any usefull links (perhaps a tutorial) for using FFmpeg? EDIT: spelling mistakes

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  • Visual Web Developer 2008 Express and XHTML 1.1 (not applying)

    - by Mike Valeriano
    Hello. I may be missing something since I'm not used to work with IDEs for web development, so please understand if I'm doing something stupid. I've picked a copy of Beginning ASP.NET 3.5 in C# and VB to try and learn this thing quickly. I'm no HTML guru, but I know something about the DTDs and I want to either use XHTML 1.0 Strict or XHTML 1.1 while learning the ins and outs of ASP.NET. Following the book (just started actually), I'm not having any trouble understanding the concepts, since I have a C# background, but what I don't understand is how VWD goes about applying the schema you select for validation. The book explains that the drop-down list on the toolbar is enough to set this, so that's what I did: I've selected XHTML 1.1 (since there is no 1.0 strict option, what I find really odd) and then started the project. The thing is that the code generated automatically for the Default page had the XHTML 1.0 transitional DTD. Every other page added had the same DTD, even though XHTML 1.1 is still the selected schema in the drop-down list. I decided to test it out and there it was: inserting some text in the design view and then applying a bold formatting just inserted < b tags on the code. Changing color does add a span tag with added CSS though. What I want to know is: if I want strict XHTML (or 1.1) should I just code it manually? Or is there a "fix" for this problem (having a schema selected but not applied by the IDE)? Am I missing something really easy and dumb? I have no problem with coding it manually - I actually prefer doing that. The thing is that I really wanna try this WYSIWYG approach for once, since some developers swear by it. Plus I don't know yet if I'll need special tags for ASP.NET, so I think having them inserted automatically should be the best practice. I couldn't find any similar problems around (MSDN, Google, here), and as far as the book goes (up to the point I've read), this is the expected VWD behavior, which I find suspect at least. Sorry for the long text (and poor English - not my primary language). Thanks in advance for any help/tips.

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  • C# Nested Property Accessing overloading OR Sequential Operator Overloading

    - by Tim
    Hey, I've been searching around for a solution to a tricky problem we're having with our code base. To start, our code resembles the following: class User { int id; int accountId; Account account { get { return Account.Get(accountId); } } } class Account { int accountId; OnlinePresence Presence { get { return OnlinePresence.Get(accountId); } } public static Account Get(int accountId) { // hits a database and gets back our object. } } class OnlinePresence { int accountId; bool isOnline; public static OnlinePresence Get(int accountId) { // hits a database and gets back our object. } } What we're often doing in our code is trying to access the account Presence of a user by doing var presence = user.Account.Presence; The problem with this is that this is actually making two requests to the database. One to get the Account object, and then one to get the Presence object. We could easily knock this down to one request if we did the following : var presence = UserPresence.Get(user.id); This works, but sort of requires developers to have an understanding of the UserPresence class/methods that would be nice to eliminate. I've thought of a couple of cool ways to be able to handle this problem, and was wondering if anyone knows if these are possible, if there are other ways of handling this, or if we just need to think more as we're coding and do the UserPresence.Get instead of using properties. Overload nested accessors. It would be cool if inside the User class I could write some sort of "extension" that would say "any time a User object's Account property's Presence object is being accessed, do this instead". Overload the . operator with knowledge of what comes after. If I could somehow overload the . operator only in situations where the object on the right is also being "dotted" it would be great. Both of these seem like things that could be handled at compile time, but perhaps I'm missing something (would reflection make this difficult?). Am I looking at things completely incorrectly? Is there a way of enforcing this that removes the burden from the user of the business logic? Thanks! Tim

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  • iPhone MailComposer class UIViewController dismissModalViewControllerAnimated issues

    - by Scott Pendleton
    I created a class to launch the MailComposer so that my iPhone app would only have one place to go when generating various kinds of e-mail: some with attachments, some not. Some with pre-filled addresses, some not. I didn't want my class implement UIViewController, but it has to so it can be the delegate for the MailComposer. Otherwise, the view controllers that call my class would themselves have to be delegates for the MailComposer, which defeats the purpose. The downside of having my class be a view controller is that it has to load to the screen before it can modally bring up the MailComposer. Unfortunately, view controllers can't be transparent. The effect is, whatever is on screen gets covered by a solid white view controller for a moment before the MailComposer appears. I could maybe live with that, but not this: after the MailComposer goes away, I'm left with my blank view controller occupying the screen. I ought to be able to get rid of it from within itself by calling this: [self.parentViewController dismissModalViewControllerAnimated:NO]; But that dies a horrible death: "Loading 43365 stack frames..." Has my class -- a UIViewController that pre-fills and then launches a MailComposer -- lost track of its parentViewController? It isn't nil, because I've tested for that. As launched from within the current view controller... // My class is called Email. Email *oEmail = [[[Email alloc] init] retain]; // Red, to remind myself that I'd like to someday learn to make it transparent. oEmail.view.backgroundColor = [UIColor redColor]; // Pre-fill whatever fields you want, and specify attachments. oEmail.EmailSubject = @"I am truly stumped"; // This has to go on screen first. [self presentModalViewController:oEmail animated:NO]; // Then this can happen, which brings up the MailComposer. [oEmail f_SendEmail]; // Commenting out the next line didn't help, so I turned it back on. [oEmail release]; Inside the class, you need the mailComposeController:didFinishWithResult:error: method to make the MailComposer go away, and for that to happen, the class has to be the MFMailComposeViewControllerDelegate. Here's what happens in there: // This gets rid of the mail composer. [self dismissModalViewControllerAnimated:YES]; // This never fails to get rid of other modal view controllers when called // from within those controllers, but boy does it not work here. [self.parentViewController dismissModalViewControllerAnimated:NO]; If you can help me, I will be truly thankful!

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  • Good Email Notification Sending Service

    - by Philibert Perusse
    I need to send a few but important email notifications to individual users. For instance, when they register their software I send them a confirmation email. Right now, I am using 'sendmail' from my Perl CGI script to do the job. Most of my automated email are lost or marked as junk. Unfortunately, I am using shared hosting services and not a very good control over the SPF and SenderID DNS records. Even more bad, some other user of that shared server has been infected with some kind of SPAM-BOT and the IP is now blacklisted until further notice! Anyway I just don't want to deal with this kind of headache. I am looking for an online service that I will be able to subscribe to and pay something like 0.10$ per email I send with no monthly fees. I just need and API to be able to send the email from PHP or Perl code I will have to write. I have been looking around at all those "Email Sending Services" and they are all wrapped around creating campains and managing lists for bulk email marketing distribution and newsletters. But remember, I want to send an email notification to a "single" recipient. So far, I have look at MailChimp, SocketLabs, iContact, ConstantContact, StreamSend and so many others to no avail. I have seen one comment at Hackers News saying that MailChimp have an API for transactional e-mails (i.e. ad-hoc ones to welcome a user for example). So you're not just restricted to using them for bulk emails But I cannot find this in the API documentation supplied, maybe this was removed. Any suggestions out there. Here is a summary of my requirements: Allows ad hoc sending of email to a single recipient. Throughput may well be throttle I don't care, i am sending like 2-5 emails a day. API available in PHP or Perl to connect to that web service. Ideally I can send HTML formatted emails, otherwise I will live with text only. Solution not too expensive, between 0.01$ and 0.25$ per email would be acceptable. No recurring monthly fees.

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  • .NET SerialPort DataReceived event thread interference with main thread

    - by Kiran
    I am writing a serial communication program using the SerialPort class in C# to interact with a strip machine connected via a RS232 cable. When i send the command to the machine it responds with some bytes depending on the command. Like when i send a "\D" command, i am expecting to download the machine program data of 180 bytes as a continous string. As per the machine's manual, it suggests as a best practice to send an unreognized characters like comma (,) character to make sure the machine is initialized before sending the first command in the cycle. My serial communication code is as follows: public class SerialHelper { SerialPort commPort = null; string currentReceived = string.Empty; string receivedStr = string.Empty; private bool CommInitialized() { try { commPort = new SerialPort(); commPort.PortName = "COM1"; if (!commPort.IsOpen) commPort.Open(); commPort.BaudRate = 9600; commPort.Parity = System.IO.Ports.Parity.None; commPort.StopBits = StopBits.One; commPort.DataBits = 8; commPort.RtsEnable = true; commPort.DtrEnable = true; commPort.DataReceived += new SerialDataReceivedEventHandler(commPort_DataReceived); return true; } catch (Exception ex) { return false; } } void commPort_DataReceived(object sender, SerialDataReceivedEventArgs e) { SerialPort currentPort = (SerialPort)sender; currentReceived = currentPort.ReadExisting(); receivedStr += currentReceived; } internal int CommIO(string outString, int outLen, ref string inBuffer, int inLen) { receivedStr = string.Empty; inBuffer = string.Empty; if (CommInitialized()) { commPort.Write(outString); } System.Threading.Thread.Sleep(1500); int i = 0; while ((receivedStr.Length < inLen) && i < 10) { System.Threading.Thread.Sleep(500); i += 1; } if (!string.IsNullOrEmpty(receivedStr)) { inBuffer = receivedStr; } commPort.Close(); return inBuffer.Length; } } I am calling this code from a windows form as follows: len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) len = SerialHelperObj.CommIO(",",1,ref inBuffer, 4) If(inBuffer == "!?*O") { len = SerialHelperObj.CommIO("\D",2,ref inBuffer, 180) } A valid return value from the serial port looks like this: \D00000010000000000010 550 3250 0000256000 and so on ... I am getting some thing like this: \D00000010D,, 000 550 D,, and so on... I feel that my comm calls are getting interferred with the one when i send commands. But i am trying to make sure the result of the comma command then initiating the actual command. but the received thread is inserting the bytes from the previous communication cycle. Can any one please shed some light into this...? I lost quite some hair just trying to get this work. I am not sure where i am doing wrong

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  • detect face from image and crop face from that photo

    - by Siddhpura Amit
    I have done coding in that i am successfully getting face with rectangle drawing now i want to crop that rectangle area. if there are many rectangle( mean many faces) than user can select one of the face or rectangle and that rectangle areal should be cropped can any body help me... Below is my code class AndroidFaceDetector extends Activity { public String path; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Bundle bundle = this.getIntent().getExtras(); path = bundle.getString("mypath"); setContentView(new myView(this)); } class myView extends View { private int imageWidth, imageHeight; private int numberOfFace = 5; private FaceDetector myFaceDetect; private FaceDetector.Face[] myFace; float myEyesDistance; int numberOfFaceDetected; Bitmap myBitmap; public myView(Context context) { super(context); System.out.println("CONSTRUCTOR"); System.out.println("path = "+path); if (path != null) { BitmapFactory.Options BitmapFactoryOptionsbfo = new BitmapFactory.Options(); BitmapFactoryOptionsbfo.inPreferredConfig = Bitmap.Config.RGB_565; myBitmap = BitmapFactory.decodeFile(path, BitmapFactoryOptionsbfo); imageWidth = myBitmap.getWidth(); imageHeight = myBitmap.getHeight(); myFace = new FaceDetector.Face[numberOfFace]; myFaceDetect = new FaceDetector(imageWidth, imageHeight, numberOfFace); numberOfFaceDetected = myFaceDetect.findFaces(myBitmap, myFace); } else { Toast.makeText(AndroidFaceDetector.this, "Please Try again", Toast.LENGTH_SHORT).show(); } } @Override protected void onDraw(Canvas canvas) { System.out.println("ON DRAW IS CALLED"); if (myBitmap != null) { canvas.drawBitmap(myBitmap, 0, 0, null); Paint myPaint = new Paint(); myPaint.setColor(Color.GREEN); myPaint.setStyle(Paint.Style.STROKE); myPaint.setStrokeWidth(3); for (int i = 0; i < numberOfFaceDetected; i++) { Face face = myFace[i]; PointF myMidPoint = new PointF(); face.getMidPoint(myMidPoint); myEyesDistance = face.eyesDistance(); canvas.drawRect((int) (myMidPoint.x - myEyesDistance), (int) (myMidPoint.y - myEyesDistance), (int) (myMidPoint.x + myEyesDistance), (int) (myMidPoint.y + myEyesDistance), myPaint); } } } } }

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  • Safari/Chrome problem with ajaxsubmit?

    - by Jan
    Hi I'm currently having some weird issues with ajaxsubmit (http://jquery.malsup.com/form/#ajaxSubmit), which I'm currently using in a project. I have a flow where I need to open a form into a modal window. I'm using fancybox for that and it works like a charm. When the form has been forced to open in the fancybox window there can happen two things. 1) If the user who is about to submit the form is logged in she should see a confirmation in the modal box, that her input was succesfully submitted 2)If the user is not logged in there should be loaded a login form once she hits the submit button 2.1) When the user has logged in she should receive a confirmation in the modal box. This is also working like a charm in Firefox, IE8 and IE7 but not in Safari or Chrome. The weird part is that it seems like safari and chrome are completely ignoring my ajaxsubmit form. To force the first form to be opened I use the follwoing script - this part is working in both Safari and Chrome. $(".klikEnPrisForm").ajaxForm({ success: function(data){ $.fancybox({'content':data}); } }); My ajaxsubmit form scrip looks like this var options = { url: '/?altTemplate=XmlProxyKlikEnPris', dataType: 'xml', data: $(this).serializeArray(), success: function(data) { if ($(data).find('loggetind').text() == 'true') { $("#klikenpris").hide(); $('<div id="fancybox-inner-klik"></div>').appendTo('#fancybox-inner'); $('#fancybox-inner-klik').load('/KlikEnPrisAccept?tilKvittering=1&sagsno=' + $(data).find('sagsnummer').text() + '&pris=' + $(data).find('pris').text() + '&klik-comment=' + $(data).find('kommentar').text() + '&klik-telefon=' + $(data).find('tlf').text() + '&klik-maeglerkontakt=' + $(data).find('maakontakte').text()).stop(true, true); } else { $("#klikenpris").hide(); $("#fancybox-wrap").css({ 'width': '480px', 'height': '220px' }); $("#fancybox-inner").css({ 'width': '460px', 'height': '220px' }); $('<div id="fancybox-inner-klik"></div>').appendTo('#fancybox-inner'); $('#fancybox-inner-klik').load('/login.aspx?loginklikpris=0&klikpris=1&sagsno=' + $(data).find('sagsnummer').text() + '&pris=' + $(data).find('pris').text() + '&klik-comment=' + $(data).find('kommentar').text() + '&klik-telefon=' + $(data).find('tlf').text() + '&klik-maeglerkontakt=' + $(data).find('maakontakte').text()).stop(true, true); } } }; // bind to the form's submit event $('#klikenprisform').submit(function() { // inside event callbacks 'this' is the DOM element so we first // wrap it in a jQuery object and then invoke ajaxSubmit $(this).ajaxSubmit(options); // !!! Important !!! // always return false to prevent standard browser submit and page navigation return false; }); I have tried inserting an alert in the succes callback function but it's never being called it seems. It seems like the default action is not being overruled by the link written in the "url" in ajaxsubmit. I'm really puzzled about this, since it's working nicely in other browsers and I'm completely lost on how I should approach the debugging in safari/chrome. I hope all the above makes sense and I'm looking forward to hear any suggestions. Cheers!

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  • Using FluentNHibernate + SQLite with .Net4?

    - by stiank81
    I have a WPF application running with .Net3.5 using FluentNHibernate, and all works fine. When I upgraded to VS2010 I ran into some odd problems, but after changing to use x64 variant of SQLite it worked fine again. Now I want to change to use .Net4, but this has turned into a more painful experience then I expected.. When calling FluentConfiguration.BuildConfiguration I get an exception thrown: FluentConfigurationException unhandled An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail The inner exception gives us more information: Message = "Could not create the driver from NHibernate.Driver.SQLite20Driver, NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4." It has an InnerException again: Exception has been thrown by the target of an invocation. Which again has an InnerException: The IDbCommand and IDbConnection implementation in the assembly System.Data.SQLite could not be found. Ensure that the assembly System.Data.SQLite is located in the application directory or in the Global Assembly Cache. If the assembly is in the GAC, use element in the application configuration file to specify the full name of the assembly. Now - to me it sounds like it doesn't find System.Data.SQLite.dll, but I can't understand this. Everywhere this is referenced I have "Copy Local", and I have verified that it is in every build folder for projects using SQLite. I have also copied it manually to every Debug folder of the solution - without luck. Notes: This exact same code worked just fine before I upgraded to .Net4. I did see some x64 x86 mismatch problems earlier, but I have switched to use x86 as the target platform and for all referenced dlls. I have verified that all files in the Debug-folder are x86. I have tried the precompiled Fluent dlls, I have tried compiling myself, and I have compiled my own version of Fluent using .Net4. I see that there are also others that have seen this problem, but I haven't really seen any solution yet. After @devio's answer I tried adding a reference to the SQLite dll. This didn't change anything, but I hope I made it right though.. This is what I added to the root node of the app.config file: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <qualifyAssembly partialName="System.Data.SQLite" fullName="System.Data.SQLite, Version=1.0.60.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139" /> </assemblyBinding> </runtime> Anyone out there using Fluent with .Net4 and SQLite successfully? Help! I'm lost...

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  • Optimizing multiple dispatch notification algorithm in C#?

    - by Robert Fraser
    Sorry about the title, I couldn't think of a better way to describe the problem. Basically, I'm trying to implement a collision system in a game. I want to be able to register a "collision handler" that handles any collision of two objects (given in either order) that can be cast to particular types. So if Player : Ship : Entity and Laser : Particle : Entity, and handlers for (Ship, Particle) and (Laser, Entity) are registered than for a collision of (Laser, Player), both handlers should be notified, with the arguments in the correct order, and a collision of (Laser, Laser) should notify only the second handler. A code snippet says a thousand words, so here's what I'm doing right now (naieve method): public IObservable<Collision<T1, T2>> onCollisionsOf<T1, T2>() where T1 : Entity where T2 : Entity { Type t1 = typeof(T1); Type t2 = typeof(T2); Subject<Collision<T1, T2>> obs = new Subject<Collision<T1, T2>>(); _onCollisionInternal += delegate(Entity obj1, Entity obj2) { if (t1.IsAssignableFrom(obj1.GetType()) && t2.IsAssignableFrom(obj2.GetType())) obs.OnNext(new Collision<T1, T2>((T1) obj1, (T2) obj2)); else if (t1.IsAssignableFrom(obj2.GetType()) && t2.IsAssignableFrom(obj1.GetType())) obs.OnNext(new Collision<T1, T2>((T1) obj2, (T2) obj1)); }; return obs; } However, this method is quite slow (measurable; I lost ~2 FPS after implementing this), so I'm looking for a way to shave a couple cycles/allocation off this. I thought about (as in, spent an hour implementing then slammed my head against a wall for being such an idiot) a method that put the types in an order based on their hash code, then put them into a dictionary, with each entry being a linked list of handlers for pairs of that type with a boolean indication whether the handler wanted the order of arguments reversed. Unfortunately, this doesn't work for derived types, since if a derived type is passed in, it won't notify a subscriber for the base type. Can anyone think of a way better than checking every type pair (twice) to see if it matches? Thanks, Robert

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  • Wrapping a pure virtual method with multiple arguments with Boost.Python

    - by fallino
    Hello, I followed the "official" tutorial and others but still don't manage to expose this pure virtual method (getPeptide) : ms_mascotresults.hpp class ms_mascotresults { public: ms_mascotresults(ms_mascotresfile &resfile, const unsigned int flags, double minProbability, int maxHitsToReport, const char * unigeneIndexFile, const char * singleHit = 0); ... virtual ms_peptide getPeptide(const int q, const int p) const = 0; } ms_mascotresults.cpp #include <boost/python.hpp> using namespace boost::python; #include "msparser.hpp" // which includes "ms_mascotresults.hpp" using namespace matrix_science; #include <iostream> #include <sstream> struct ms_mascotresults_wrapper : ms_mascotresults, wrapper<ms_mascotresults> { ms_peptide getPeptide(const int q, const int p) { this->get_override("getPeptide")(q); this->get_override("getPeptide")(p); } }; BOOST_PYTHON_MODULE(ms_mascotresults) { class_<ms_mascotresults_wrapper, boost::noncopyable>("ms_mascotresults") .def("getPeptide", pure_virtual(&ms_mascotresults::getPeptide) ) ; } Here are the bjam's errors : /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp:66: error: cannot declare field ‘boost::python::objects::value_holder<ms_mascotresults_wrapper>::m_held’ to be of abstract type ‘ms_mascotresults_wrapper’ ms_mascotresults.cpp:12: note: because the following virtual functions are pure within ‘ms_mascotresults_wrapper’: ... include/ms_mascotresults.hpp:334: note: virtual matrix_science::ms_peptide matrix_science::ms_mascotresults::getPeptide(int, int) const ms_mascotresults.cpp: In constructor ‘ms_mascotresults_wrapper::ms_mascotresults_wrapper()’: ms_mascotresults.cpp:12: error: no matching function for call to ‘matrix_science::ms_mascotresults::ms_mascotresults()’ include/ms_mascotresults.hpp:284: note: candidates are: matrix_science::ms_mascotresults::ms_mascotresults(matrix_science::ms_mascotresfile&, unsigned int, double, int, const char*, const char*) include/ms_mascotresults.hpp:109: note: matrix_science::ms_mascotresults::ms_mascotresults(const matrix_science::ms_mascotresults&) ... /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp: In constructor ‘boost::python::objects::value_holder<Value>::value_holder(PyObject*) [with Value = ms_mascotresults_wrapper]’: /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp:137: note: synthesized method ‘ms_mascotresults_wrapper::ms_mascotresults_wrapper()’ first required here /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp:137: error: cannot allocate an object of abstract type ‘ms_mascotresults_wrapper’ ms_mascotresults.cpp:12: note: since type ‘ms_mascotresults_wrapper’ has pure virtual functions So I tried to change the constructor's signature by : BOOST_PYTHON_MODULE(ms_mascotresults) { //class_<ms_mascotresults_wrapper, boost::noncopyable>("ms_mascotresults") class_<ms_mascotresults_wrapper, boost::noncopyable>("ms_mascotresults", init<ms_mascotresfile &, const unsigned int, double, int, const char *,const char *>()) .def("getPeptide", pure_virtual(&ms_mascotresults::getPeptide) ) Giving these errors : /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp:66: error: cannot declare field ‘boost::python::objects::value_holder<ms_mascotresults_wrapper>::m_held’ to be of abstract type ‘ms_mascotresults_wrapper’ ms_mascotresults.cpp:12: note: because the following virtual functions are pure within ‘ms_mascotresults_wrapper’: include/ms_mascotresults.hpp:334: note: virtual matrix_science::ms_peptide matrix_science::ms_mascotresults::getPeptide(int, int) const ... ms_mascotresults.cpp:24: instantiated from here /usr/local/boost_1_42_0/boost/python/object/value_holder.hpp:137: error: no matching function for call to ‘ms_mascotresults_wrapper::ms_mascotresults_wrapper(matrix_science::ms_mascotresfile&, const unsigned int&, const double&, const int&, const char* const&, const char* const&)’ ms_mascotresults.cpp:12: note: candidates are: ms_mascotresults_wrapper::ms_mascotresults_wrapper(const ms_mascotresults_wrapper&) ms_mascotresults.cpp:12: note: ms_mascotresults_wrapper::ms_mascotresults_wrapper() If I comment the virtual function getPeptide in the .hpp, it builds perfectly with this constructor : class_<ms_mascotresults>("ms_mascotresults", init<ms_mascotresfile &, const unsigned int, double, int, const char *,const char *>() ) So I'm a bit lost...

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  • Need help manipulating WAV (RIFF) Files at a byte level

    - by Eric
    I'm writing an an application in C# that will record audio files (*.wav) and automatically tag and name them. Wave files are RIFF files (like AVI) which can contain meta data chunks in addition to the waveform data chunks. So now I'm trying to figure out how to read and write the RIFF meta data to and from recorded wave files. I'm using NAudio for recording the files, and asked on their forums as well on SO for way to read and write RIFF tags. While I received a number of good answers, none of the solutions allowed for reading and writing RIFF chunks as easily as I would like. But more importantly I have very little experience dealing with files at a byte level, and think this could be a good opportunity to learn. So now I want to try writing my own class(es) that can read in a RIFF file and allow meta data to be read, and written from the file. I've used streams in C#, but always with the entire stream at once. So now I'm little lost that I have to consider a file byte by byte. Specifically how would I go about removing or inserting bytes to and from the middle of a file? I've tried reading a file through a FileStream into a byte array (byte[]) as shown in the code below. System.IO.FileStream waveFileStream = System.IO.File.OpenRead(@"C:\sound.wav"); byte[] waveBytes = new byte[waveFileStream.Length]; waveFileStream.Read(waveBytes, 0, waveBytes.Length); And I could see through the Visual Studio debugger that the first four byte are the RIFF header of the file. But arrays are a pain to deal with when performing actions that change their size like inserting or removing values. So I was thinking I could then to the byte[] into a List like this. List<byte> list = waveBytes.ToList<byte>(); Which would make any manipulation of the file byte by byte a whole lot easier, but I'm worried I might be missing something like a class in the System.IO name-space that would make all this even easier. Am I on the right track, or is there a better way to do this? I should also mention that I'm not hugely concerned with performance, and would prefer not to deal with pointers or unsafe code blocks like this guy. If it helps at all here is a good article on the RIFF/WAV file format.

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  • How to Practice Unix Programming in C?

    - by danben
    After five years of professional Java (and to a lesser extent, Python) programming and slowly feeling my CS education slip away, I decided I wanted to broaden my horizons / general usefulness to the world and do something that feels more (to me) like I really have an influence over the machine. I chose to learn C and Unix programming since I feel like that is where many of the most interesting problems are. My end goal is to be able to do this professionally, if for no other reason than the fact that I have to spend 40-50 hours per week on work that pays the bills, so it may as well also be the type of coding I want to get better at. Of course, you don't get hired to do things you haven't dont before, so for now I am ramping up on my own. To this end, I started with K&R, which was a great resource in part due to the exercises spread throughout each chapter. After that I moved on to Computer Systems: A Programmer's Perspective, followed by ten chapters of Advanced Programming in the Unix Environment. When I am done with this book, I will read Unix Network Programming. What I'm missing in the Stevens books is the lack of programming problems; they mainly document functionality and provide examples, with a few end-of-chapter questions following. I feel that I would benefit much more from being challenged to use the knowledge in each chapter ala K&R. I could write some test program for each function, but this is a less desirable method as (1) I would probably be less motivated than if I were rising to some external challenge, and (2) I will naturally only think to use the function in the ways that have already occurred to me. So, I'd like to get some recommendations on how to practice. Obviously, my first choice would be to find some resource that has Unix programming challenges. I have also considered finding and attempting to contribute to some open source C project, but this is a bit daunting as there would be some overhead in learning to use the software, then learning the codebase. The only open-source C project I can think of that I use regularly is Python, and I'm not sure how easy that would be to get started on. That said, I'm open to all kinds of suggestions as there are likely things I haven't even thought of.

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  • Inline-editing: onBlur prevents onClick from being triggered (jQuery)

    - by codethief
    Hello StackOverflow community! I'm currently working on my own jQuery plugin for inline-editing as those that already exist don't fit my needs. Anyway, I'd like to give the user the following (boolean) options concerning the way editing is supposed to work: submit_button reset_on_blur Let's say the user would like to have a submit button (submit_button = true) and wants the inline input element to be removed as soon as it loses focus (reset_on_blur = true). This leads to an onClick handler being registered for the button and an onBlur handler being registered for the input element. Every time the user clicks the button, however, the onBlur handler is also triggered and results in the edit mode being left, i.e. before the onClick event occurs. This makes submitting impossible. FYI, the HTML in edit mode looks like this: <td><input type="text" class="ie-input" value="Current value" /><div class="ie-content-backup" style="display: none;">Backup Value</div><input type="submit" class="ie-button-submit" value="Save" /></td> So, is there any way I could check in the onBlur handler if the focus was lost while activating the submit button, so that edit mode isn't left before the submit button's onClick event is triggered? I've also tried to register a $('body').click() handler to simulate blur and to be able to trace back which element has been clicked, but that didn't work either and resulted in rather strange bugs: $('html').click(function(e) { // body doesn't span over full page height, use html instead // Don't reset if the submit button, the input element itself or the element to be edited inline was clicked. if(!$(e.target).hasClass('ie-button-submit') && !$(e.target).hasClass('ie-input') && $(e.target).get(0) != element.get(0)) { cancel(element); } }); jEditable uses the following piece of code. I don't like this approach, though, because of the delay. Let alone I don't even understand why this works. ;) input.blur(function(e) { /* prevent canceling if submit was clicked */ t = setTimeout(function() { reset.apply(form, [settings, self]); }, 500); }); Thanks in advance!

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  • Using embedded resources in Silverlight (4) - other cultures not being compiled

    - by Andrei Rinea
    I am having a bit of a hard time providing localized strings for the UI in a small Silverlight 4 application. Basically I've put a folder "Resources" and placed two resource files in it : Statuses.resx Statuses.ro.resx I do have an enum Statuses : public enum Statuses { None, Working } and a convertor : public class StatusToMessage : IValueConverter { public object Convert(object value, Type targetType, object parameter, CultureInfo culture) { if (!Enum.IsDefined(typeof(Status), value)) { throw new ArgumentOutOfRangeException("value"); } var x = Statuses.None; return Statuses.ResourceManager.GetString(((Status)value).ToString(), Thread.CurrentThread.CurrentUICulture); } public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture) { throw new NotImplementedException(); } } in the view I have a textblock : <TextBlock Grid.Column="3" Text="{Binding Status, Converter={StaticResource StatusToMessage}}" /> Upon view rendering the converter is called but no matter what the Thread.CurrentThread.CurrentUICulture is set it always returns the default culture value. Upon further inspection I took apart the XAP resulted file, taken the resulted DLL file to Reflector and inspected the embedded resources. It only contains the default resource!! Going back to the two resource files I am now inspecting their properties : Build action : Embedded Resource Copy to output directory : Do not copy Custom tool : ResXFileCodeGenerator Custom tool namespace : [empty] Both resource (.resx) files have these settings. The .Designer.cs resulted files are as follows : Statuses.Designer.cs : //------------------------------------------------------------------------------ // <auto-generated> // This code was generated by a tool. // Runtime Version:4.0.30319.1 // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ namespace SilverlightApplication5.Resources { using System; /// <summary> /// A strongly-typed resource class, for looking up localized strings, etc. /// </summary> // This class was auto-generated by the StronglyTypedResourceBuilder // class via a tool like ResGen or Visual Studio. // To add or remove a member, edit your .ResX file then rerun ResGen // with the /str option, or rebuild your VS project. [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")] [global::System.Diagnostics.DebuggerNonUserCodeAttribute()] [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()] internal class Statuses { // ... yadda-yadda Statuses.ro.Designer.cs [empty] I've taken both files and put them in a console application and they behave as expected in it, not like in this silverlight application. What is wrong?

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  • Windows Service HTTPListener Memory Issue

    - by crawshaws
    Hi all, Im a complete novice to the "best practices" etc of writing in any code. I tend to just write it an if it works, why fix it. Well, this way of working is landing me in some hot water. I am writing a simple windows service to server a single webpage. (This service will be incorperated in to another project which monitors the services and some folders on a group of servers.) My problem is that whenever a request is recieved, the memory usage jumps up by a few K per request and keeps qoing up on every request. Now ive found that by putting GC.Collect in the mix it stops at a certain number but im sure its not meant to be used this way. I was wondering if i am missing something or not doing something i should to free up memory. Here is the code: Public Class SimpleWebService : Inherits ServiceBase 'Set the values for the different event log types. Public Const EVENT_ERROR As Integer = 1 Public Const EVENT_WARNING As Integer = 2 Public Const EVENT_INFORMATION As Integer = 4 Public listenerThread As Thread Dim HTTPListner As HttpListener Dim blnKeepAlive As Boolean = True Shared Sub Main() Dim ServicesToRun As ServiceBase() ServicesToRun = New ServiceBase() {New SimpleWebService()} ServiceBase.Run(ServicesToRun) End Sub Protected Overrides Sub OnStart(ByVal args As String()) If Not HttpListener.IsSupported Then CreateEventLogEntry("Windows XP SP2, Server 2003, or higher is required to " & "use the HttpListener class.") Me.Stop() End If Try listenerThread = New Thread(AddressOf ListenForConnections) listenerThread.Start() Catch ex As Exception CreateEventLogEntry(ex.Message) End Try End Sub Protected Overrides Sub OnStop() blnKeepAlive = False End Sub Private Sub CreateEventLogEntry(ByRef strEventContent As String) Dim sSource As String Dim sLog As String sSource = "Service1" sLog = "Application" If Not EventLog.SourceExists(sSource) Then EventLog.CreateEventSource(sSource, sLog) End If Dim ELog As New EventLog(sLog, ".", sSource) ELog.WriteEntry(strEventContent) End Sub Public Sub ListenForConnections() HTTPListner = New HttpListener HTTPListner.Prefixes.Add("http://*:1986/") HTTPListner.Start() Do While blnKeepAlive Dim ctx As HttpListenerContext = HTTPListner.GetContext() Dim HandlerThread As Thread = New Thread(AddressOf ProcessRequest) HandlerThread.Start(ctx) HandlerThread = Nothing Loop HTTPListner.Stop() End Sub Private Sub ProcessRequest(ByVal ctx As HttpListenerContext) Dim sb As StringBuilder = New StringBuilder sb.Append("<html><body><h1>Test My Service</h1>") sb.Append("</body></html>") Dim buffer() As Byte = Encoding.UTF8.GetBytes(sb.ToString) ctx.Response.ContentLength64 = buffer.Length ctx.Response.OutputStream.Write(buffer, 0, buffer.Length) ctx.Response.OutputStream.Close() ctx.Response.Close() sb = Nothing buffer = Nothing ctx = Nothing 'This line seems to keep the mem leak down 'System.GC.Collect() End Sub End Class Please feel free to critisise and tear the code apart but please BE KIND. I have admitted I dont tend to follow the best practice when it comes to coding.

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  • How would you organize a large complex web application (see basic example)?

    - by Anurag
    How do you usually organize complex web applications that are extremely rich on the client side. I have created a contrived example to indicate the kind of mess it's easy to get into if things are not managed well for big apps. Feel free to modify/extend this example as you wish - http://jsfiddle.net/NHyLC/1/ The example basically mirrors part of the comment posting on SO, and follows the following rules: Must have 15 characters minimum, after multiple spaces are trimmed out to one. If Add Comment is clicked, but the size is less than 15 after removing multiple spaces, then show a popup with the error. Indicate amount of characters remaining and summarize with color coding. Gray indicates a small comment, brown indicates a medium comment, orange a large comment, and red a comment overflow. One comment can only be submitted every 15 seconds. If comment is submitted too soon, show a popup with appropriate error message. A couple of issues I noticed with this example. This should ideally be a widget or some sort of packaged functionality. Things like a comment per 15 seconds, and minimum 15 character comment belong to some application wide policies rather than being embedded inside each widget. Too many hard-coded values. No code organization. Model, Views, Controllers are all bundled together. Not that MVC is the only approach for organizing rich client side web applications, but there is none in this example. How would you go about cleaning this up? Applying a little MVC/MVP along the way? Here's some of the relevant functions, but it will make more sense if you saw the entire code on jsfiddle: /** * Handle comment change. * Update character count. * Indicate progress */ function handleCommentUpdate(comment) { var status = $('.comment-status'); status.text(getStatusText(comment)); status.removeClass('mild spicy hot sizzling'); status.addClass(getStatusClass(comment)); } /** * Is the comment valid for submission */ function commentSubmittable(comment) { var notTooSoon = !isTooSoon(); var notEmpty = !isEmpty(comment); var hasEnoughCharacters = !isTooShort(comment); return notTooSoon && notEmpty && hasEnoughCharacters; } // submit comment $('.add-comment').click(function() { var comment = $('.comment-box').val(); // submit comment, fake ajax call if(commentSubmittable(comment)) { .. } // show a popup if comment is mostly spaces if(isTooShort(comment)) { if(comment.length < 15) { // blink status message } else { popup("Comment must be at least 15 characters in length."); } } // show a popup is comment submitted too soon else if(isTooSoon()) { popup("Only 1 comment allowed per 15 seconds."); } });

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  • user generated / user specific functions

    - by pedalpete
    I'm looking for the most elegant and secure method to do the following. I have a calendar, and groups of users. Users can add events to specific days on the calendar, and specify how long each event lasts for. I've had a few requests from users to add the ability for them to define that events of a specific length include a break, of a certain amount of time, or require that a specific amount of time be left between events. For example, if event is 2 hours, include a 20min break. for each event, require 30 minutes before start of next event. The same group that has asked for an event of 2 hours to include a 20 min break, could also require that an event 3 hours include a 30 minute break. In the end, what the users are trying to get is an elapsed time excluding breaks calculated for them. Currently I provide them a total elapsed time, but they are looking for a running time. However, each of these requests is different for each group. Where one group may want a 30 minute break during a 2 hour event, and another may want only 10 minutes for each 3 hour event. I was kinda thinking I could write the functions into a php file per group, and then include that file and do the calculations via php and then return a calculated total to the user, but something about that doesn't sit right with me. Another option is to output the groups functions to javascript, and have it run client-side, as I'm already returning the duration of the event, but where the user is part of more than one group with different rules, this seems like it could get rather messy. I currently store the start and end time in the database, but no 'durations', and I don't think I should be storing the calculated totals in the db, because if a group decides to change their calculations, I'd need to change it throughout the db. Is there a better way of doing this? I would just store the variables in mysql, but I don't see how I can then say to mysql to calculate based on those variables. I'm REALLY lost here. Any suggestions? I'm hoping somebody has done something similar and can provide some insight into the best direction. If it helps, my table contains eventid, user, group, startDate, startTime, endDate, endTime, type The json for the event which I return to the user is {"eventid":"'.$eventId.'", "user":"'.$userId.'","group":"'.$groupId.'","type":"'.$type.'","startDate":".$startDate.'","startTime":"'.$startTime.'","endDate":"'.$endDate.'","endTime":"'.$endTime.'","durationLength":"'.$duration.'", "durationHrs":"'.$durationHrs.'"} where for example, duration length is 2.5 and duration hours is 2:30.

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  • iGoogle Stack Overflow Gadget [closed]

    - by Charango
    Since SO's question database is becoming an excellent first point of call for finding answers to coding problems, some people (like me) might like to be able to fire up searches from their iGoogle home page, among the other searches you might launch from there. I've created a very simple gadget to do this, and put the source below. My hope is that this might provide a foundation on which community members with better ideas for performing this function, or ideas for enhancing it, can update it. Perhaps we could make it configurable to search via a site scope search from Google and / or a question search, for instance. I've hosted and registered this first version but if anyone makes changes and can host a new version / new pics elsewhere, please feel free. <?xml version="1.0" encoding="UTF-8"?> <Module> <ModulePrefs title="Stack Overflow Search" author="Community Wiki" author_email="[email protected]" author_affiliation="Stack Overflow" author_location="The Internet" author_aboutme="All sorts" author_link="http://stackoverflow.com" author_quote="Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law." description="Stack Overflow is rapidly becoming one of the best resources for finding answers to your programming questions. This gadget adds a question search box to your iGoogle homepage" screenshot="http://arkios-solutions.com/misc/sogadget/SOGadget.png" thumbnail="http://arkios-solutions.com/misc/sogadget/SOGadget_Thumbnail.png" singleton="true" title_url="http://stackoverflow.com" /> <Content type="html"><![CDATA[ <img src="http://i.stackoverflow.com/Content/Img/stackoverflow-logo-250.png" alt="Stackoverflow Logo"/> <div style="font-family:arial;font-size:0.8em;"> This gadget allows you to search the Stack Overflow question database. </div> <form name='SOQueryForm' action="http://stackoverflow.com/search" method="get" target="new"> <p>Your question: <input type='text' size='34' name='q' /></p> <p><input type='submit' value='Go' /></p> </form> ]]> </Content> </Module> The source / installable gadget xml are also hosted here.

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  • GOTO still considered harmful?

    - by Kyle Cronin
    Everyone is aware of Dijkstra's Letters to the editor: go to statement considered harmful (also here .html transcript and here .pdf) and there has been a formidable push since that time to eschew the goto statement whenever possible. While it's possible to use goto to produce unmaintainable, sprawling code, it nevertheless remains in modern programming languages. Even the advanced continuation control structure in Scheme can be described as a sophisticated goto. What circumstances warrant the use of goto? When is it best to avoid? As a followup question: C provides a pair of functions, setjmp and longjmp, that provide the ability to goto not just within the current stack frame but within any of the calling frames. Should these be considered as dangerous as goto? More dangerous? Dijkstra himself regretted that title, of which he was not responsible for. At the end of EWD1308 (also here .pdf) he wrote: Finally a short story for the record. In 1968, the Communications of the ACM published a text of mine under the title "The goto statement considered harmful", which in later years would be most frequently referenced, regrettably, however, often by authors who had seen no more of it than its title, which became a cornerstone of my fame by becoming a template: we would see all sorts of articles under the title "X considered harmful" for almost any X, including one titled "Dijkstra considered harmful". But what had happened? I had submitted a paper under the title "A case against the goto statement", which, in order to speed up its publication, the editor had changed into a "letter to the Editor", and in the process he had given it a new title of his own invention! The editor was Niklaus Wirth. A well thought out classic paper about this topic, to be matched to that of Dijkstra, is Structured Programming with go to Statements (also here .pdf), by Donald E. Knuth. Reading both helps to reestablish context and a non-dogmatic understanding of the subject. In this paper, Dijkstra's opinion on this case is reported and is even more strong: Donald E. Knuth: I believe that by presenting such a view I am not in fact disagreeing sharply with Dijkstra's ideas, since he recently wrote the following: "Please don't fall into the trap of believing that I am terribly dogmatical about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!"

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  • Multi-part question about multi-threading, locks and multi-core processors (multi ^ 3)

    - by MusiGenesis
    I have a program with two methods. The first method takes two arrays as parameters, and performs an operation in which values from one array are conditionally written into the other, like so: void Blend(int[] dest, int[] src, int offset) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } The second method creates two separate sets of int arrays and iterates through them such that each array of one set is Blended with each array from the other set, like so: void CrossBlend() { int[][] set1 = new int[150][75000]; // we'll pretend this actually compiles int[][] set2 = new int[25][10000]; // we'll pretend this actually compiles for (int i1 = 0; i1 < set1.Length; i1++) { for (int i2 = 0; i2 < set2.Length; i2++) { Blend(set1[i1], set2[i2], 0); // or any offset, doesn't matter } } } First question: Since this apporoach is an obvious candidate for parallelization, is it intrinsically thread-safe? It seems like no, since I can conceive a scenario (unlikely, I think) where one thread's changes are lost because a different threads ~simultaneous operation. If no, would this: void Blend(int[] dest, int[] src, int offset) { lock (dest) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } } be an effective fix? Second question: If so, what would be the likely performance cost of using locks like this? I assume that with something like this, if a thread attempts to lock a destination array that is currently locked by another thread, the first thread would block until the lock was released instead of continuing to process something. Also, how much time does it actually take to acquire a lock? Nanosecond scale, or worse than that? Would this be a major issue in something like this? Third question: How would I best approach this problem in a multi-threaded way that would take advantage of multi-core processors (and this is based on the potentially wrong assumption that a multi-threaded solution would not speed up this operation on a single core processor)? I'm guessing that I would want to have one thread running per core, but I don't know if that's true.

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  • How should I provide access to this custom DAL?

    - by Casey
    I'm writing a custom DAL (VB.NET) for an ordering system project. I'd like to explain how it is coded now, and receive some alternate ideas to make coding against the DAL easier/more readable. The DAL is part of an n-tier (not n-layer) application, where each tier is in it's own assembly/DLL. The DAL consists of several classes that have specific behavior. For instance, there is an Order class that is responsible for retrieving and saving orders. Most of the classes have only two methods, a "Get" and a "Save," with multiple overloads for each. These classes are marked as Friend and are only visible to the DAL (which is in it's own assembly). In most cases, the DAL returns what I will call a "Data Object." This object is a class that contains only data and validation, and is located in a common assembly that both the BLL and DAL can read. To provide public access to the DAL, I currently have a static (module) class that has many shared members. A simplified version looks something like this: Public Class DAL Private Sub New End Sub Public Shared Function GetOrder(OrderID as String) as OrderData Dim OrderGetter as New OrderClass Return OrderGetter.GetOrder(OrderID) End Function End Class Friend Class OrderClass Friend Function GetOrder(OrderID as string) as OrderData End Function End Class The BLL would call for an order like this: DAL.GetOrder("123456") As you can imagine, this gets cumbersome very quickly. I'm mainly interested in structuring access to the DAL so that Intellisense is very intuitive. As it stands now, there are too many methods/functions in the DAL class with similar names. One idea I had is to break down the DAL into nested classes: Public Class DAL Private Sub New End Sub Public Class Orders Private Sub New End Sub Public Shared Function Get(OrderID as string) as OrderData End Function End Class End Class So the BLL would call like this: DAL.Orders.Get("12345") This cleans it up a bit, but it leaves a lot of classes that only have references to other classes, which I don't like for some reason. Without resorting to passing DB specific instructions (like where clauses) from BLL to DAL, what is the best or most common practice for providing a single point of access for the DAL?

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  • Drawing Bresenham’s Line- Algorithm in all quadrants

    - by Yoyo2965259
    I am newbie for OpenGL. I am practicing the exercises from my textbook but I could not get the outputs which is should be in Bresenham's Line Algorithm in all quadrants. Here's the coding: #include <Windows.h> #include <GL/glut.h> void init(void) { glClearColor(0.0, 0.0, 0.0, 0.0); glShadeModel(GL_FLAT); } void BresnCir(void) { int delta, deltadash; glClear(GL_COLOR_BUFFER_BIT); glPointSize(3.0); int r = 150; int x = 0; int y = r; int D = 2 * (1 - r); glBegin(GL_POINTS); do { glVertex2i(x, y); if (D < 0) { delta = 2 * D + 2 * y - 1; if (delta <= 0) { x++; Right(x); } else { x++; y--; Diagonal(x, y); } glVertex2i(x, y); } else { deltadash = 2 * D - 2 * x - 1; if (deltadash <= 0) { x++; y--; Diagonal(x, y); } else { y--; Down(y); } glVertex2i(x, y); } if (D == 0) { x++; y--; Diagonal(x, y); glVertex2i(x, y); } } while (y > 0); glEnd(); glFlush(); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(400, 150); glutInitWindowPosition(100, 100); glutCreateWindow(argv[0]); init(); glutDisplayFunc(BresnCir); glutMainLoop(); return 0; } But, it keep comes out with errors C3861.

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