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• Fastest inline-assembly spinlock

  - by sigvardsen

  I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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• Mercurial repository usage with binary files for building setup files

  - by Ryan

  I have an existing Mercurial repository for a C++ application in a small corporate environment. I asked a co-worker to add the setup script to the repository and he added all of the dependency binaries, PDFs, and executable to the repository under an Install directory. I dislike having the binaries and dependencies in the same repository, but I'd like recommendations on best practices. Here are the options I am considering: Create a separate repository for the Installer and related files Create a subrepository for the Installer and related files Use a (yet to be identified) build dependency manager I am concerned with using a subrepository with Mercurial based on what I've read so far and the (apparently) incomplete implementation. I would like to get a project dependency system, e.g. Ivy, but I don't know all of the options and haven't had time yet to try out any options. I thought I'd use TortoiseHg as a basis, and it does not have the TortoiseHg binaries in the repository although it does have some binaries such as kdiff3.exe. Instead it uses setup.py to clone multiple repositories and build the apps. This seems reasonable for OSS, but not so much for corporate environments. Recommendations?

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• Attempting to Convert Byte[] into Image... but is there platform issues involved

  - by user305535

  Greetings, Current, I'm attempting to develop an application that takes a Byte Array that is streamed to us from a Linux C language program across a TCPClient (stream) and reassemble it back into an image/jpg. The "sending" application was developed by a off-site developer who claims that the image reassembles back into an image without any problems or errors in his test environment (all Linux)... However, we are not so fortunate. I (believe) we successfully get all of the data sent, storing it as a string (lets us append the stream until it is complete) and then we convert it back into a Byte[]. This appears to be working fine... But, when we take the byte[] we get from the streaming (and our string assembly) and try to convert it into an image using the System.Drawing.Image.FromStream() we get errors.... Anyone have any idea what we're doing wrong? Or, does anyone know if this is a cross-platform issue? We're developing our app for Windows XP and C# .net, but the off-site developer did his work in c and Linux... perhaps there's some difference as to how each Operating System Coverts Images into Byte Arrays? Anyway, here's the code for converting our received ByteArray (from the TCPClient Stream) into an image. This code works when we send an image from a test machine we built that RUNS on XP, but not from the Linux box... System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding(); byte[] imageBytes = encoding.GetBytes(data); MemoryStream ms = new MemoryStream(imageBytes, 0, imageBytes.Length); // Convert byte[] to Image ms.Write(imageBytes, 0, imageBytes.Length); System.Drawing.Image image = System.Drawing.Image.FromStream(ms, false); <-- DIES here, throws a {System.ArgumentException: Parameter is not valid.} error Any advice, suggestions, theories, or HELP would be GREATLY appreciated! Please let me know??? Best wishes all! Thanks in advance! Greg

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• Sticky/static variable references in for loops

  - by pthulin

  In this example I create three buttons 'one' 'two' 'three'. When clicked I want them to alert their number: <html> <head> <script type="application/javascript" src="jquery.js"></script> <script type="application/javascript"> $(document).ready(function() { var numbers = ['one', 'two', 'three']; for (i in numbers) { var nr = numbers[i]; var li = $('<li>' + nr + '</li>'); li.click(function() { var newVariable = String(nr); alert(i); // 2 alert(nr); // three alert(newVariable); // three alert(li.html()); // three }); $('ul').append(li); } }); </script> </head> <body> <ul> </ul> </body> </html> The problem is, when any of these are clicked, the last value of the loop's variables is used, i.e. alert box always says 'three'. In JavaScript, variables inside for-loops seem to be 'static' in the C language sense. Is there some way to create separate variables for each click function, i.e. not using the same reference? Thanks!

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• Is there a standard pattern for scanning a job table executing some actions?

  - by Howiecamp

  (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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• Testing ActionFilterAttributes with MSpec

  - by Tomas Lycken

  I'm currently trying to grasp MSpec, mainly to learn new ways of (T/B)DD to be able to make an educated decision on which technology to use. Previously, I've mostly (read: only) used the built-in MSTest framework with Moq, so BDD is quite new for me. I'm writing an ASP.NET MVC app, and I want to implement PRG. Last time I did this, I used action filters to export and import ModelState via TempData, so that I could return a RedirectResult and the validation errors would still be there when the user got the view. I tested that scenario by verifying two things: a) That the ExportModelStateAttribute I had written was applied (among tests for my controller) b) That the attribute worked (among tests for action filter attributes) However, in BDD I've understood I should be even more concerned with behavior, and even less with implementation. This means I should probably just verify that the model state is in tempdata when the action has finished executing - not necessarily that it's done via an attribute. To further complicate things, attributes are not run when calling the action directly in the test, so I can't just call the action and see if the job's been done. How should I spec/test this in MSpec?

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• php OOP function declarations

  - by kris

  I'm a big fan of OOP in php, but i feel like defining class methods gets disorganized so fast. I have a pretty good background in OOP in C++, and i am pretty comfortable with how it is handled there, and am curious if there are ways to do it similarly in php. To be more specific, here is what i mean. I like how in C++ you can define a class header (myclass.h) and then define the actual details of the functions in the implementation file (myclass.cc). Ive found that this can easily be replicated using interfaces in php, but i havent found a good solution for the following: I like to organize my code in C++ in different files based on how they are accessed, so for example, public methods that can be called outside of the class would be in 1 place, and private methods would be organized somewhere else - this is personal preference. Ive tried to define class methods in php like: private function MyPHPClass::myFunction(){ } when the definition isnt directly inside the class block( { } ), but i havent had any success doing this. Ive been through all of the pages on php.net, but couldnt find anything like this. Im assuming that there is no support for something like this, but thought i would ask anyway. thanks

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• In Python, how can I find the index of the first item in a list that is NOT some value?

  - by Ryan B. Lynch

  Python's list type has an index(x) method. It takes a single parameter x, and returns the (integer) index of the first item in the list that has the value x. Basically, I need to invert the index(x) method. I need to get the index of the first value in a list that does NOT have the value x. I would probably be able to even just use a function that returns the index of the first item with a value != None. I can think of a 'for' loop implementation with an incrementing counter variable, but I feel like I'm missing something. Is there an existing method, or a one-line Python construction that can handle this? In my program, the situation comes up when I'm handling lists returned from complex regex matches. All but one item in each list have a value of None. If I just needed the matched string, I could use a list comprehension like '[x for x in [my_list] if x is not None]', but I need the index in order to figure out which capture group in my regex actually caused the match.

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• Unity in C# for Platform Specific Implementations

  - by DxCK

  My program has heavy interaction with the operating system through Win32API functions. now i want to migrate my program to run under Mono under Linux (No wine), and this requires different implementations to the interaction with the operating system. I started designing a code that can have different implementation for difference platform and is extensible for new future platforms. public interface ISomeInterface { void SomePlatformSpecificOperation(); } [PlatformSpecific(PlatformID.Unix)] public class SomeImplementation : ISomeInterface { #region ISomeInterface Members public void SomePlatformSpecificOperation() { Console.WriteLine("From SomeImplementation"); } #endregion } public class PlatformSpecificAttribute : Attribute { private PlatformID _platform; public PlatformSpecificAttribute(PlatformID platform) { _platform = platform; } public PlatformID Platform { get { return _platform; } } } public static class PlatformSpecificUtils { public static IEnumerable<Type> GetImplementationTypes<T>() { foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies()) { foreach (Type type in assembly.GetTypes()) { if (typeof(T).IsAssignableFrom(type) && type != typeof(T) && IsPlatformMatch(type)) { yield return type; } } } } private static bool IsPlatformMatch(Type type) { return GetPlatforms(type).Any(platform => platform == Environment.OSVersion.Platform); } private static IEnumerable<PlatformID> GetPlatforms(Type type) { return type.GetCustomAttributes(typeof(PlatformSpecificAttribute), false) .Select(obj => ((PlatformSpecificAttribute)obj).Platform); } } class Program { static void Main(string[] args) { Type first = PlatformSpecificUtils.GetImplementationTypes<ISomeInterface>().FirstOrDefault(); } } I see two problems with this design: I can't force the implementations of ISomeInterface to have a PlatformSpecificAttribute. Multiple implementations can be marked with the same PlatformID, and i dont know witch to use in the Main. Using the first one is ummm ugly. How to solve those problems? Can you suggest another design?

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• UINaviagtionBar not displaying?

  - by Rajendra Bhole

  Hi, I developing an application in which initially choose UINavigationController based application. In rooViewController xib i added two more UIView, the code is written as follows. @implementation RootViewController @synthesize introductionView, WheelView; (void)viewDidLoad { [super viewDidLoad]; [self.navigationController setNavigationBarHidden:YES]; } pragma mark pragma mark strart up screen: -(void)startIntroductionScreen{ if(window == nil) { window = [[UIWindow alloc] initWithFrame:CGRectMake(0, 0, 320, 480)]; } [window addSubview: introductionView]; [window makeKeyAndVisible]; } -(void)WheelScreen{ [window addSubview:carnivalWheelView]; [window makeKeyAndVisible]; self.navigationController.navigationBar.hidden = NO; [self.navigationItem setLeftBarButtonItem:[[UIBarButtonItem alloc] initWithTitle:@"Setting" style:UIBarButtonItemStylePlain target:nil action:nil] animated:YES]; } pragma mark pragma mark IBAction: -(IBAction)breakGlass:(id)sender{ [self startIntroductionScreen]; } -(IBAction)anotherView:(id)sender{ [self WheelScreen]; } In above code, when the -(void)WheelScreen method on the IBAction anotherView of invoke the UINaviagtionBar is not displaying. Thank's in advance.

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• creating matrix with probabilities

  - by John Chan

  Hi all, I want to generate a matrix of NxN to test some code that I have where each row contains floats as the elements and has to add up to 1 (i.e. a row with a set of probabilities). Where it gets tricky is that I want to make sure that randomly some of the elements should be 0 (in fact most of the elements should be 0 except for some random ones to be the probabilities). I need the probabilities to be 1/m where m is the number of elements that are not 0 within a single row. I tried to think of ways to output this, but essentially I would need this stored in a C++ array. So even if I output to a file I would still have the issue of not having it in array as I need it. At the end of it all I need that array because I want to generate a Market Matrix file. I found an implementation in C++ to take an array and convert it to the market matrix file, so this is what I am basing my findings on. My input for the rest of the code takes in this market matrix file so I need that to be the primary form of output. The language does not matter, I just want to generate the file at the end (I found a way mmwrite and mmread in python as well) Please help, I am stuck and not really sure how to implement this.

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• Class unloading in java

  - by java_geek

  When a classloader is garbage collected, are the classes loaded by it unloaded? When the JVM is running is verbose mode, all the loaded classes are o/p. Similarly will the JVM log when it unloads a class? I wrote a custom class loader to test this, but could not see any verbose log for unloading of the classes. CustomClassLoader loader = new CustomClassLoader(new URL[]{}, CustomClassLoader.class.getClassLoader()); loader.addURL("D:\workspace\ClassLoaderTest\implementation.jar"); Class c = null; try { c = Class.forName("Horse",false,loader); if (c != null) { try { Animal animal = (Animal)c.newInstance(); animal.eat(); } catch(Exception ex) { ex.printStackTrace(); } } } catch(Exception e) { e.printStackTrace(); } loader = null; byte[] b = new byte[58*1024*1024]; System.gc(); ClassLoadingMXBean clBean = ManagementFactory.getClassLoadingMXBean(); System.out.println("Number of classes currently loaded " + clBean.getLoadedClassCount()); System.out.println("Number of classes loaded totally " + clBean.getTotalLoadedClassCount()); System.out.println("Number of classes unloaded " + clBean.getUnloadedClassCount()); Even the ClassLoadingMXBean gives number of unloaded classes as 0. How can i know that a class is unloaded when the class loader is GCed?

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• Is this a bug in plist or Xcode?

  - by Pedro

  G'day All If you create a date item in the plist editor of Xcode or Apple's standalone plist editor you get something of the form <date>2010-05-29T10:30:00Z</date> which is a nice well formed ISO date at UTC (indicated by the "Z"). Because I'm in timezone UTC +10 when that's read into my app & then displayed I get 8:30 PM out, still good. However if that is a time in my timezone it should be <date>2010-05-29T10:30:00+10</date> (replacing "Z" with my timezone offset). All of my attempts at reading such dates into my iPhone app have had the plist rejected as if it is malformed & editing a plist with such a date in Apple's editors changed the "+10" to "Z" without adjusting the time. Do others think I'm correct in thinking this is a bug in either plist or Xcode? My feeling is that the implementation of ISO date & time in plist is incomplete. Cheers, Pedro :)

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• Is Stream.Write thread-safe?

  - by Mike Spross

  I'm working on a client/server library for a legacy RPC implementation and was running into issues where the client would sometimes hang when waiting to a receive a response message to an RPC request message. It turns out the real problem was in my message framing code (I wasn't handling message boundaries correctly when reading data off the underlying NetworkStream), but it also made me suspicious of the code I was using to send data across the network, specifically in the case where the RPC server sends a large amount of data to a client as the result of a client RPC request. My send code uses a BinaryWriter to write a complete "message" to the underlying NetworkStream. The RPC protocol also implements a heartbeat algorithm, where the RPC server sends out PING messages every 15 seconds. The pings are sent out by a separate thread, so, at least in theory, a ping can be sent while the server is in the middle of streaming a large response back to a client. Suppose I have a Send method as follows, where stream is a NetworkStream: public void Send(Message message) { //Write the message to a temporary stream so we can send it all-at-once MemoryStream tempStream = new MemoryStream(); message.WriteToStream(tempStream); //Write the serialized message to the stream. //The BinaryWriter is a little redundant in this //simplified example, but here because //the production code uses it. byte[] data = tempStream.ToArray(); BinaryWriter bw = new BinaryWriter(stream); bw.Write(data, 0, data.Length); bw.Flush(); } So the question I have is, is the call to bw.Write (and by implication the call to the underlying Stream's Write method) atomic? That is, if a lengthy Write is still in progress on the sending thread, and the heartbeat thread kicks in and sends a PING message, will that thread block until the original Write call finishes, or do I have to add explicit synchronization to the Send method to prevent the two Send calls from clobbering the stream?

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• Getting around IBActions limited scope

  - by Septih

  Hello, I have an NSCollectionView and the view is an NSBox with a label and an NSButton. I want a double click or a click of the NSButton to tell the controller to perform an action with the represented object of the NSCollectionViewItem. The Item View is has been subclassed, the code is as follows: #import <Cocoa/Cocoa.h> #import "WizardItem.h" @interface WizardItemView : NSBox { id delegate; IBOutlet NSCollectionViewItem * viewItem; WizardItem * wizardItem; } @property(readwrite,retain) WizardItem * wizardItem; @property(readwrite,retain) id delegate; -(IBAction)start:(id)sender; @end #import "WizardItemView.h" @implementation WizardItemView @synthesize wizardItem, delegate; -(void)awakeFromNib { [self bind:@"wizardItem" toObject:viewItem withKeyPath:@"representedObject" options:nil]; } -(void)mouseDown:(NSEvent *)event { [super mouseDown:event]; if([event clickCount] > 1) { [delegate performAction:[wizardItem action]]; } } -(IBAction)start:(id)sender { [delegate performAction:[wizardItem action]]; } @end The problem I've run into is that as an IBAction, the only things in the scope of -start are the things that have been bound in IB, so delegate and viewItem. This means that I cannot get at the represented object to send it to the delegate. Is there a way around this limited scope or a better way or getting hold of the represented object? Thanks.

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• problem with image gallery using fancybox jquery

  - by Alexander

  I am trying to use fancybox for one of my image galery and my code is the following.. this is the code for my Gallery.aspx where it inherits from a master page... For some reason it doesn't work.. can you guys tell me what the problem is? <%@ Page Title="" Language="C#" MasterPageFile="~/Global.Master" AutoEventWireup="true" CodeBehind="Gallery.aspx.cs" Inherits="Permias.Gallery" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server"> <script src="jquery.js" type="text/javascript"></script> <script type="text/javascript" src="http://code.jquery.com/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="./fancybox/jquery.fancybox-1.3.1.pack.js"></script> <script type="text/javascript" src="./fancybox/jquery.easing-1.3.pack.js"></script> <script type="text/javascript" src="./fancybox/jquery.mousewheel-3.0.2.pack.js"></script> <link rel="stylesheet" href="./fancybox/jquery.fancybox-1.3.1.css" type="text/css" media="screen" /> </asp:Content> <asp:Content ID="Content3" ContentPlaceHolderID="splash" runat="server"> <div id="splash">&nbsp;</div> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server"> <a class="grouped_elements" rel="group1" href="http://farm5.static.flickr.com/4058/4252054277_f0fa91e026.jpg"><img src="http://farm5.static.flickr.com/4058/4252054277_f0fa91e026.jpg" alt=""/></a> </asp:Content>

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• Animation is slow on iPhone

  - by Anthony Chan

  I'm developing an app that would display images and change them according to the user's action. I've created a subclass of UIView to contain an image, an index number and an array of image names. The code is like this: @interface CustomPic : UIView { UIImageView *pic; NSInteger index; NSMutableArray *picNames; //<-- an array of NSString } And in the implementation part, it has a method to change the image using a dissolve effect. - (void)nextPic { index++; if (index >= [picNames count]) { index = 0; } UIImageView *temp = pic; pic.image = [UIImage imageNamed:[picNames objectAtIndex:index]]; temp.alpha = 0; [UIView beginAnimations:nil context:nil]; [UIView setAnimationCurve:UIViewAnimationCurveEaseOut]; [UIView setAnimationDuration:0.25]; pic.alpha = 0; temp.alpha = 1; [UIView commitAnimations]; } In the viewController, there are several CustomPic which would change the images depends on users' choice. The images would change as expected with the fade in/out effect, but the animation performance is really bad. I've tested it on an iPhone 3G, the Instruments shows that the animation is only 2-3FPS! I tried many methods to simplify and modify the codes but with no hope. Is there something wrong in my code or in my concept? Thanks for any help. P.S. all the images are 320*480 PNGs with a max size of 15KB.

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• error message The URI does not identify an external Java class

  - by iHeartGreek

  Hi! I am new to XSL, and thus new to using scripts within the XSL. I have taken example code (also using C#) and adapted it for my own use.. but it does not work. The error message is: The URI urn:cs-scripts does not identify an external Java class The relevant code I have is: <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl" xmlns:strTok="urn:cs-scripts"> ... ... ... </xsl:template> <xsl:variable name="temp"> <xsl:value-of select="tok:getList('AAA BBB CCC', ' ')"/> </xsl:variable> <msxsl:script language="C#" implements-prefix="tok"> <![CDATA[ public string[] getList(string str, char[] delim) { return str.Split(delim, StringSplitOptions.None); } public string getString(string[] list, int i) { return list[i]; } ]]> </msxsl:script> </xsl:stylesheet>

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• Using ADO.NET Entities LINQ Provider to model complex SQL Queries?

  - by Ivan Zlatanov

  What I find really powerful in ADO.NET Entities or LINQ to SQL, is the ability to model complex queries. I really don't need the mappings that Entities or LINQ to SQL are doing for me - I just need the ability to model complex expressions that can be translated into T-SQL. My question is - am I abusing too much? Can I use the Entity Framework for modeling queries and just that? Should I? I know I can write my own custom LINQ to SQL provider, but that is just not possible to handle in the time spans I have. What is the best approach to model complex T-SQL queries? How do you handle conditional group byes, orders, joins, unions etc in the OOP world? Using StringBuilders for this kind of job feels too ugly and harder to maintain given the possibilities we have with Expression Trees. When I use StringBuilder to model a complex SQL Query I feel kind of guilty! I feel the same way as when I have to hard code any number into my code that is different than 0 or 1. Feeling that makes you ask yourself if there is a better and cleaner way of doing it... I must mention that I am using C# 4.0, but I am not specifically looking for an answer in this language, but rather in the domain of CLR 4.

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• [Javascript] Linux Ajax (mootools Request.JSON) Header error

  - by VDVLeon

  Hi all, I use the following code to get some json data: var request = new Request.JSON( { 'url': sourceURI, 'onSuccess': onPageData } ); request.get(); Request.JSON is a class from Mootools (a javascript library). But on linux (ubuntu on firefox 3.5 and Chrome) the request always fails. So i tried to display the http request ajax is sending. (I used netcat to display it) The request is like this: OPTIONS /the+url HTTP/1.1 Host: example.com Connection: keep-alive User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US) AppleWebKit/532.3 (KHTML, like Gecko) Chrome/4.0.226.0 Safari/532.3 Referer: http://example.com/ref... Access-Control-Request-Method: GET Origin: http://example.com Access-Control-Request-Headers: X-Request, X-Requested-With, Accept Accept: */* Accept-Encoding: gzip,deflate Accept-Language: en-US,en;q=0.8 Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3 The HTTP request (first line) is not how it should be: OPTIONS /the+url HTTP/1.1 It should be: GET /the+url HTTP/1.1 Does anybody know why this problem is and how to fix it?

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• Are there any code critique sites or similar resources?

  - by Ukko

  I have noticed when people post example code illustrating some issue that they are having often they will gather a number of comments addressing the quality of the code they presented and not the actual problem asked. This is very helpful--if not well directed. Often, this is wasted effort since the asker is often not receptive and the code is often chopped down to something small to post leaving lots of rough edges. In the old days you would see people asking questions like this on comp.lang.lisp and other parts of the comp.lang hierarchy. But that bit of the net kind of sank into the sewers of neglect. Is there a comparable one-stop-shop today? I am partially asking for selfish reasons, I know how to write good idiomatic C, Lisp, O'Caml, and Java code. But I learned C++ pre-template and STL, those rusty skills are not really applicable to today's C++. I have picked up languages like Scala in a vacuum and get by, but am I really doing it correctly? There are so many ways you can abuse a language, I am currently working against a codebase of Fortran written in C, and I recognize and loathe the "that guy" who wrote it. I don't want to be someone else's "that guy" if I can help it. Just because it works does not mean that one did not totally miss the boat on how it should have been done. Do you seek out this type of critique? If so how, where and why? What types of benefits do you derive from it? How about abuse and trolls?

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• C++ operator lookup rules / Koenig lookup

  - by John Bartholomew

  While writing a test suite, I needed to provide an implementation of operator<<(std::ostream&... for Boost unit test to use. This worked: namespace theseus { namespace core { std::ostream& operator<<(std::ostream& ss, const PixelRGB& p) { return (ss << "PixelRGB(" << (int)p.r << "," << (int)p.g << "," << (int)p.b << ")"); } }} This didn't: std::ostream& operator<<(std::ostream& ss, const theseus::core::PixelRGB& p) { return (ss << "PixelRGB(" << (int)p.r << "," << (int)p.g << "," << (int)p.b << ")"); } Apparently, the second wasn't included in the candidate matches when g++ tried to resolve the use of the operator. Why (what rule causes this)? The code calling operator<< is deep within the Boost unit test framework, but here's the test code: BOOST_AUTO_TEST_SUITE(core_image) BOOST_AUTO_TEST_CASE(test_output) { using namespace theseus::core; BOOST_TEST_MESSAGE(PixelRGB(5,5,5)); // only compiles with operator<< definition inside theseus::core std::cout << PixelRGB(5,5,5) << "\n"; // works with either definition BOOST_CHECK(true); // prevent no-assertion error } BOOST_AUTO_TEST_SUITE_END() For reference, I'm using g++ 4.4 (though for the moment I'm assuming this behaviour is standards-conformant).

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• Safe and polymorphic toEnum

  - by jetxee

  I'd like to write a safe version of toEnum: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t A naive implementation: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t safeToEnum i = if (i >= fromEnum (minBound :: t)) && (i <= fromEnum (maxBound :: t)) then Just . toEnum $ i else Nothing main = do print $ (safeToEnum 1 :: Maybe Bool) print $ (safeToEnum 2 :: Maybe Bool) And it doesn't work: safeToEnum.hs:3:21: Could not deduce (Bounded t1) from the context () arising from a use of `minBound' at safeToEnum.hs:3:21-28 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(minBound :: t)' In the second argument of `(>=)', namely `fromEnum (minBound :: t)' In the first argument of `(&&)', namely `(i >= fromEnum (minBound :: t))' safeToEnum.hs:3:56: Could not deduce (Bounded t1) from the context () arising from a use of `maxBound' at safeToEnum.hs:3:56-63 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(maxBound :: t)' In the second argument of `(<=)', namely `fromEnum (maxBound :: t)' In the second argument of `(&&)', namely `(i <= fromEnum (maxBound :: t))' As well as I understand the message, the compiler does not recognize that minBound and maxBound should produce exactly the same type as in the result type of safeToEnum inspite of the explicit type declaration (:: t). Any idea how to fix it?

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• MVC View Model Intellesense / Compile error

  - by Marty Trenouth

  I have one Library with my ORM and am working with a MVC Application. I have a problem where the pages won't compile because the Views can't see the Model's properties (which are inherited from lower level base classes). They system throws a compile error saying that 'object' does not contain a definition for 'ID' and no extension method 'ID' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?) implying that the View is not seeing the model. In the Controller I have full access to the Model and have check the Inherits from portion of the view to validate the correct type is being passed. Controller: return View(new TeraViral_Blog()); View: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<com.models.TeraViral_Blog>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Index2 </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Index2</h2> <fieldset> <legend>Fields</legend> <p> ID: <%= Html.Encode(Model.ID) %> </p> </fieldset> </asp:Content>

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• iPhone Adding Controls (UIButton, UILabel etc.) on a Playing Video!

  - by Taimur Hamza

  I have been assigned an 'easy' task of adding a button over a playing video. I m terming it easy as i have got the sample code downloaded from Apple's sample code. http://rapidshare.com/files/393248642/MoviePlayer_iPhone.zip Anybody who wants to reply to my query and intends to help should download this project and run it otherwise it wudnt be easy to understand my problem. Thanks! And now the weird problem i am facing is: In the sample project developer has added the view ( UILabel and UIButton ) in the Appdelegate. And i want it other xib files not the App delegate . Fine i added a view 'myButtonABC' instead of 'My Overlay View'. And added this code in my xib file's implementation file. (void)viewDidLoad { TaimurAppDelegate *appDelegate = (TaimurAppDelegate *)[[UIApplication sharedApplication] delegate]; [appDelegate initAndPlayMovie:[self localMovieURL]]; NSArray *windows = [[UIApplication sharedApplication] windows]; if ([windows count] 1) { UIWindow *moviePlayerWindow = [[UIApplication sharedApplication] keyWindow]; [moviePlayerWindow addSubview:self.myABC]; } } Now my question is do i need to declare a UIWindow object in the header file here. As i am not working in the app delegate class. As i said previously i have to add this button over a video in other screen and not on the main screen. The third question is can anyone, which in fact is the most imp of all. In my view , if i am able to do this one my problem would be solved. As i have spend considerable amount of time on this task so far. The question is " How can i connect myABCButton (which is a view added to my xib file ) to the File's Owner. Thanks for your patience. Replies Appreciated ! Taimur

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