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  • How can we change views in a UISplitViewController other than using the popover and selecting?

    - by wolverine
    I have done a sample app with UISplitViewController studying the example they have provided. I have created three detailviews and have configured them to change by the default means. Either using the left/master view in landscape AND using the popover in the portrait orientation. Now I am trying to move to another view(previous/next) from the currentView by using left/right swipe in each view. For that, what I did was just created a function in the RootViewController. I copy-pasted the same code as that of the tablerow selection used by the popover from the RootViewController. I am calling this function from my current view's controller and is passing the respective index of the view(to be displayed next) from the current view. Function is being called but nothing is happening. Plz help me OR is anyother way to do it other than this complex step? I am giving the function that I used to change the view. - (void) rearrangeViews:(int)viewRow { UIViewController <SubstitutableDetailViewController> *detailViewController = nil; if (viewRow == 0) { DetailViewController *newDetailViewController = [[DetailViewController alloc] initWithNibName:@"DetailView" bundle:nil]; detailViewController = newDetailViewController; } if (viewRow == 1) { SecondDetailViewController *newDetailViewController = [[SecondDetailViewController alloc] initWithNibName:@"SecondDetailView" bundle:nil]; detailViewController = newDetailViewController; } if (viewRow == 2) { ThirdDetailViewController *newDetailViewController = [[ThirdDetailViewController alloc] initWithNibName:@"ThirdDetailView" bundle:nil]; detailViewController = newDetailViewController; } // Update the split view controller's view controllers array. NSArray *viewControllers = [[NSArray alloc] initWithObjects:self.navigationController, detailViewController, nil]; splitViewController.viewControllers = viewControllers; [viewControllers release]; if (rootPopoverButtonItem != nil) { [detailViewController showRootPopoverButtonItem:self.rootPopoverButtonItem]; } [detailViewController release]; }

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  • Making Javascript and HTML5 games

    - by Jeff Meatball Yang
    A long time ago (Netscape 4-era), I wrote Javascript-based games: Pong, Minesweeper, and John Conway's Life among them. I'm getting back into it, and want to get my hands even dirtier. I have a few games in mind: Axis & Allies clone, with rugged maps and complex rules. Tetris clone, possibly with real-time player-vs-player or player-vs-computer mode Breakout clone, with a couple weapons and particle velocities In all of these, I have only a few objectives: Use JavaScript and HTML 5 - it should run on Chrome, Safari, or maybe an iPad. Start small and simple, then build-up features. Learn something new about game design and implementation. So my questions are: How would you implement these games? Do you have any technology recommendations? If you've written these games, what was the hardest part? N.B. I also want to start from first-principles - if you recommend a framework/library, I would appreciate some theory or implementation details behind it. These games are different enough that I should learn something new from each one.

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  • Is it possible to execute a function in Mongo that accepts any parameters?

    - by joshua.clayton
    I'm looking to write a function to do a custom query on a collection in Mongo. Problem is, I want to reuse that function. My thought was this (obviously contrived): var awesome = function(count) { return function() { return this.size == parseInt(count); }; } So then I could do something along the lines of: db.collection.find(awesome(5)); However, I get this error: error: { "$err" : "error on invocation of $where function: JS Error: ReferenceError: count is not defined nofile_b:1" } So, it looks like Mongo isn't honoring scope, but I'm really not sure why. Any insight would be appreciated. To go into more depth of what I'd like to do: A collection of documents has lat/lng values, and I want to find all documents within a concave or convex polygon. I have the function written but would ideally be able to reuse the function, so I want to pass in an array of points composing my polygon to the function I execute on Mongo's end. I've looked at Mongo's geospatial querying and it currently on supports circle and box queries - I need something more complex.

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  • Detecting Connection Speed / Bandwidth in .net/WCF

    - by Mystagogue
    I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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  • How can I access mainframe data with .Net applications and SQL Queries?

    - by orandov
    We have a large amount of data stored on an IBM mainframe using VSAM files. A lot of this data is dropped on the network every night in the form of text files to be processed and dumped into FoxPro and SQL Server databases. There are also many text files produced nightly by custom applications that get uploaded to the mainframe to keep everything in sync. Keeping the everything in sync is very tricky, to say the least. We are not getting rid of the mainframe any time soon and we would like to replace all the nightly batch processing with real time access to the mainframe data. We would like to be able to: Read data directly from the mainframe and produce reports based on it. Possibly using SQL queries. Read and Write data from custom .Net applications. We are not looking for a new platform to interface with the mainframe like Information Builders offers. We don't want to build application modules or reports with new "Business Intelligence" tools. We already know how to generate reports and write custom applications using SQL,.Net, Visual Studio, etc. All we are looking for is some sort of adapter to connect to our mainframe data. Any ideas are appreciated.

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  • Read from one large file and write to many (tens, hundreds, or thousands) files in Java?

    - by Rudiger
    I have a large-ish file (4-5 GB compressed) of small messages that I wish to parse into approximately 6,000 files by message type. Messages are small; anywhere from 5 to 50 bytes depending on the type. Each message starts with a fixed-size type field (a 6-byte key). If I read a message of type '000001', I want to write append its payload to 000001.dat, etc. The input file contains a mixture of messages; I want N homogeneous output files, where each output file contains only the messages of a given type. What's an efficient a fast way of writing these messages to so many individual files? I'd like to use as much memory and processing power to get it done as fast as possible. I can write compressed or uncompressed files to the disk. I'm thinking of using a hashmap with a message type key and an outputstream value, but I'm sure there's a better way to do it. Thanks!

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  • Why is there no autorelease pool when I do performSelectorInBackground: ?

    - by Thanks
    I am calling a method that goes in a background thread: [self performSelectorInBackground:@selector(loadViewControllerWithIndex:) withObject:[NSNumber numberWithInt:viewControllerIndex]]; then, I have this method implementation that gets called by the selector: - (void) loadViewControllerWithIndex:(NSNumber *)indexNumberObj { NSAutoreleasePool *arPool = [[NSAutoreleasePool alloc] init]; NSInteger vcIndex = [indexNumberObj intValue]; Class c; UIViewController *controller = [viewControllers objectAtIndex:vcIndex]; switch (vcIndex) { case 0: c = [MyFirstViewController class]; break; case 1: c = [MySecondViewController class]; break; default: NSLog(@"unknown index for loading view controller: %d", vcIndex); // error break; } if ((NSNull *)controller == [NSNull null]) { controller = [[c alloc] initWithNib]; [viewControllers replaceObjectAtIndex:vcIndex withObject:controller]; [controller release]; } if (controller.view.superview == nil) { UIView *placeholderView = [viewControllerPlaceholderViews objectAtIndex:vcIndex]; [placeholderView addSubview:controller.view]; } [arPool release]; } Althoug I do create an autorelease pool there for that thread, I always get this error: 2009-05-30 12:03:09.910 Demo[1827:3f03] *** _NSAutoreleaseNoPool(): Object 0x523e50 of class NSCFNumber autoreleased with no pool in place - just leaking Stack: (0x95c83f0f 0x95b90442 0x28d3 0x2d42 0x95b96e0d 0x95b969b4 0x93a00155 0x93a00012) If I take away the autorelease pool, I get a whole bunch of messages like these. I also tried to create an autorelease pool around the call of the performSelectorInBackground:, but that doesn't help. I suspect the parameter, but I don't know why the compiler complains about an NSCFNumber. Am I missing something? My Instance variables are all "nonatomic". Can that be a problem? UPDATE: I may also suspect that some variable has been added to an autorelease pool of the main thread (maybe an ivar), and now it trys to release that one inside the wrong autorelease pool? If so, how could I fix that? (damn, this threading stuff is complex ;) )

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  • .NET: How to know when serialization is completed?

    - by Ian Boyd
    When I construct my control (which inherits DataGrid), I add specific rows and columns. This works great at design time. Unfortunately, at runtime I add my rows and columns in the same constructor, but then the DataGrid is serialized (after the constructor runs) adding more rows and columns. After serialization is complete, I need to clear everything and re-initialize the rows and columns. Is there a protected method that I can override to know when the control is done serializing? Of course, I'd prefer to not have to do the work in the constructor, throw it away, and do it again after (potential) serialization. Is there a preferred event that is the equivalent of "set yourself up now", so that it is called once whether I'm serialized or not? The serialization i speak of comes from the InitializeComponent() method in the form's code-behind file. #region Windows Form Designer generated code /// <summary> /// Required method for Designer support - do not modify /// the contents of this method with the code editor. /// </summary> private void InitializeComponent() { ... } It would have been perfect if InitializeComponent was a virtual method defined by Control, then i could just override it and then perform my processing after i call base: protected override void InitializeComponent() { base.InitializeComponent(); InitializeMe(); } But it's not an ancestor method, it's declared only in the code-behind file. i notice that InitializeComponent calls SuspendLayout and ResumeLayout on various Controls. i thought it could override ResumeLayout, and perform my initialization then: public override void ResumeLayout() { base.ResumeLayout(); InitializeMe(); } But ResumeLayout is not virtual, so that's out. Anymore ideas? i can't be the first person to create a custom control.

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  • Programmatically controlled virtual drive

    - by Robert Lin
    How would I go about creating a virtual drive with which I can programmatically and dynamically change the contents? For instance, program A starts running and creates a virtual drive. When program B looks in the drive, it sees an error log and starts reading/processing it. In the middle of all this program A gets a signal from somewhere and decides to add to the log. I want program B to be unaware of the change and just keep on going. Program B should continue reading as if nothing happened. Program A would just report a rediculously large file size for the log and then fill it in as appropriate. Program A would fill the log with tags if program B tries to read past the last entry. I know this is a weird request but there's really no other way to do this... I basically can't rewrite program B so I need to fool it. How do I do this in windows? How about OSX?

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  • Best way to detect similar email addresses?

    - by Chris
    I have a list of ~20,000 email addresses, some of which I know to be fraudulent attempts to get around a "1 per e-mail" limit. ([email protected], [email protected], [email protected], etc...). I want to find similar email addresses for evaluation. Currently I'm using a levenshtein algorithm to check each e-mail against the others in the list and report any with an edit distance of less than 2. However, this is painstakingly slow. Is there a more efficient approach? The test code I'm using now is: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Threading; namespace LevenshteinAnalyzer { class Program { const string INPUT_FILE = @"C:\Input.txt"; const string OUTPUT_FILE = @"C:\Output.txt"; static void Main(string[] args) { var inputWords = File.ReadAllLines(INPUT_FILE); var outputWords = new SortedSet<string>(); for (var i = 0; i < inputWords.Length; i++) { if (i % 100 == 0) Console.WriteLine("Processing record #" + i); var word1 = inputWords[i].ToLower(); for (var n = i + 1; n < inputWords.Length; n++) { if (i == n) continue; var word2 = inputWords[n].ToLower(); if (word1 == word2) continue; if (outputWords.Contains(word1)) continue; if (outputWords.Contains(word2)) continue; var distance = LevenshteinAlgorithm.Compute(word1, word2); if (distance <= 2) { outputWords.Add(word1); outputWords.Add(word2); } } } File.WriteAllLines(OUTPUT_FILE, outputWords.ToArray()); Console.WriteLine("Found {0} words", outputWords.Count); } } }

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  • Creating a smart text generator

    - by royrules22
    I'm doing this for fun (or as 4chan says "for teh lolz") and if I learn something on the way all the better. I took an AI course almost 2 years ago now and I really enjoyed it but I managed to forget everything so this is a way to refresh that. Anyway I want to be able to generate text given a set of inputs. Basically this will read forum inputs (or maybe Twitter tweets) and then generate a comment based on the learning. Now the simplest way would be to use a Markov Chain Text Generator but I want something a little bit more complex than that as the MKC basically only learns by word order (which word is more likely to appear after word x given the input text). I'm trying to see if there's something I can do to make it a little bit more smarter. For example I want it to do something like this: Learn from a large selection of posts in a message board but don't weight it too much For each post: Learn from the other comments in that post and weigh these inputs higher Generate comment and post See what other users' reaction to your post was. If good weigh it positively so you make more posts that are similar to the one made, and vice versa if negative. It's the weighing and learning from mistakes part that I'm not sure how to implement. I thought about Artificial Neural Networks (mainly because I remember enjoying that chapter) but as far as I can tell that's mainly used to classify things (i.e. given a finite set of choices [x1...xn] which x is this given input) not really generate anything. I'm not even sure if this is possible or if it is what should I go about learning/figuring out. What algorithm is best suited for this? To those worried that I will use this as a bot to spam or provide bad answers to SO, I promise that I will not use this to provide (bad) advice or to spam for profit. I definitely will not post it's nonsensical thoughts on SO. I plan to use it for my own amusement. Thanks!

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  • Umlaute from JSP-page are misinterpreted

    - by Karin
    I'm getting Input from a JSP page, that can contain Umlaute. (e.g. Ä,Ö,Ü,ä,ö,ü,ß). Whenever an Umlaut is entered in the Input field an incorrect value gets passed on. e.g. If an "ä" (UTF-8:U+00E4) gets entered in the input field, the String that is extracted from the argument is "ä" (UTF-8: U+00C3 and U+00A4) It seems to me as if the UTF-8 hex encoding (which is c3 a4 for an "ä") gets used for the conversion. How can I retrieved the correct value? Here are snippets from the current implementation The JSP-page passes the input value "pk" on to the processing logic: <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> ... <input type="text" name="<%=pk.toString()%>" value="<%=value%>" size="70"/> <button type="submit" title="Edit" value='Save' onclick="action.value='doSave';pk.value='<%=pk.toString()%>'"><img src="icons/run.png"/>Save</button> The value gets retrieved from args and converted to a string: UUID pk = UUID.fromString(args.get("pk")); //$NON-NLS-1$ String value = args.get(pk.toString()); Note: Umlaute that are saved in the Database get displayed correctly on the page.

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  • sending mail in rails from tutorial - outdated?

    - by Stacia
    I'm trying to use this tutorial (http://www.tutorialspoint.com/ruby-on-rails-2.1/rails-send-emails.htm) to send mail on rails, but nothing seems to happen. I have ActionMailer::Base.delivery_method = :sendmail in my environment.rb. It's possible the tutorial may be out of date for the more recent version of rails? If so can someone tell me where it goes wrong or a link to another tutorial. I see this in the log. It's a little supsicious that the "to" has subject and stuff appended to it, but I don't know where it went wrong. Processing EmailerController#sendmail (for 127.0.0.1 at 2010-03-10 19:02:21) [POST] Parameters: {"commit"=>"Send", "authenticity_token"=>"251d315cc4dfc6c58c2c7f6f633d52b101d10c14", "email"=>{"recipient"=>"[email protected]", "subject"=>"booooooo", "message"=>"aabdsaf"}} SQL (0.1ms) SET NAMES 'utf8' SQL (0.1ms) SET SQL_AUTO_IS_NULL=0 Sent mail to subject, booooooo, recipient, [email protected], message, aabdsaf Date: Wed, 10 Mar 2010 19:02:21 -0800 From: [email protected] To: [email protected] Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Hi! You are having one email message from [email protected] with a title This is title and following is the message: Thanks edit: I manually changed "recipient" to my mail address and I still don't get mail, even though the problem in the log with all of the things stuck together is fixed.

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  • Perl+Image::Magick usage: how to assemble several areas in one image into a new image?

    - by Jin
    Hi Everybody, I'm new to ImageMagick and haven't figured out how to assemble several areas into a new image. E.g., I know the "geometry" of words "hello" and "world" respectively in an image, what I need to do is to retrieve the word images and put then into one line image while keep their relative positions. Question1: Suppose I use the perl API, how should I use Composite() or other correct methods to do this? my $geom = sprintf('%dx%x+%d+%d', $word->{width}, $word->{height}, $offsetx, $offsety); $x = $lineimg->Composite($wordimg, $geom); warn "$x" if "$x"; Suppose $lineimg's size is big enough to hold all word images and the geometry has been computed. This code gives out a complain by ImageMagick: Exception 410: composite image required `Image::Magick' @ Magick.xs/XS_Image__Magick_Mogrify/7790 ... Question2: currently I only know how to crop a word image out of the original one and then Clone() method to restore the original image. Is there a way to copy instead of crop a specific area from a image? This way can save the time to copy back and forth the whole image several times. Does anybody know how to write this kind of processing? I appreciate all your help and suggestions! -Jin

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  • Ultra-Portable Laptop or Tablet PC for Development and Sketching

    - by Nelson LaQuet
    I am a software developer that primarily writes in PHP, [X]HTML, CSS, Javascript, C# and C++. I use Eclipse for web development, Visual Studio 2008 for C++ and C# work, TortoiseSVN, Subversion server for local repositories, SQL Server Express, Apache and MYSQL. I also use Office 2007 for word processing and spreadsheets and use Vista Ultimate 64 as my primary operating system. The only other things I do on my laptop are watch movies, surf the internet and listen to music. I currently have a Acer Aspire 5100 (1.4 GHz AMD Turion X2, 2 GB of RAM and a 15.4" screen). This thing does not cut it in performance or portability, and in addition, my DVD drive failed. And before anybody posts about vista: I have had XP Professional 32 on it for the last two years, and recently upgraded to Vista 64. It is actually faster (with areo disabled) then XP; so it is not the OS that is causing the laptop to be slow. I usually sketch a lot, for explaining things, developing user interfaces and software architecture. Because of my requirements, I was thinking about a Lenovo X61 Tablet PC. It outperforms my current laptop, is significantly more portable, and... is a tablet. My question is: do any other software developers use this (or other tablets) for programming? Does it help to be able to sketch on the computer itself? And is it capable of being a good development machine? Will it handle the above software listed? If not, what is the best ultra-portable laptop that is good for programming? Or are ultra-portable laptops even good for programming? I could manage with my 15.4" screen, but am spoiled by my two 19" at my home desktop and my job's workstation.

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  • Python: Catching / blocking SIGINT during system call

    - by danben
    I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in <module> main() ... File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/socket.py", line 397, in readline data = recv(1) socket.error: [Errno 4] Interrupted system call and the process exits completely. Why does this happen? Is there a way I can prevent the interrupt from affecting the system call?

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  • De-normalization alternative to specific MYSQL problem?

    - by Booker
    I am facing quite a specific optimization problem. I currently have 4 normalized tables of data. Every second, possibly thousands of users will pull down up-to-date info from these tables using AJAX. The thing is that I can predict relatively easily which subset of data they need... The most recent 100 or so entries in those 4 normalized tables. I have been researching de-normalization... but feel that perhaps there is an easier solution. I was thinking that I could somehow every second run one sql query to condense the needed info, store it in a temp cached table and then have all of the user queries just draw from this. This will allow the complex join of 4 tables to only be run once, and then from there the users just need to do a simple lookup from the cached table. I really don't know if this is feasible. Comments on this or any other suggestions would be much appreciated. Thanks!

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  • How do tools like Hiphop for PHP deal with heterogenous arrays?

    - by Derek Thurn
    I think HipHop for PHP is an interesting tool. It essentially converts PHP code into C++ code. Cross compiling in this manner seems like a great idea, but I have to wonder, how do they overcome the fundamental differences between the two type systems? One specific example of my general question is heterogeneous data structures. Statically typed languages don't tend to let you put arbitrary types into an array or other container because they need to be able to figure out the types on the other end. If I have a PHP array like this: $mixedBag = array("cat", 42, 8.5, false); How can this be represented in C++ code? One option would be to use void pointers (or the superior version, boost::any), but then you need to cast when you take stuff back out of the array... and I'm not at all convinced that the type inferencer can always figure out what to cast to at the other end. A better option, perhaps, would be something more like a union (or boost::variant), but then you need to enumerate all possible types at compile time... maybe possible, but certainly messy since arrays can contain arbitrarily complex entities. Does anyone know how HipHop and similar tools which go from a dynamic typing discipline to a static discipline handle these types of problems?

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  • Why execution of a portion of code loaded from external file is not halted by the OS?

    - by menjaraz
    I've harnessed a project released on internet a long time ago. Here comes the details, all irrelevant things being stripped off for sake of concision and clarity. A binary file whose content is descibed below HEX DUMP: 55 89 E5 83 EC 08 C7 45 FC 00 00 00 00 8B 45 FC 3B 45 10 72 02 EB 19 8B 45 FC 8B 55 0C 01 C2 8B 45 FC 03 45 08 8A 00 88 02 8D 45 FC FF 00 EB DD C6 45 FA 00 83 7D 10 01 76 6C 80 7D FA 00 74 02 EB 64 C6 45 FA 01 C7 45 FC 00 00 00 00 8B 45 10 48 39 45 FC 72 02 EB E2 8B 45 FC 8B 4D 0C 01 C1 8B 45 FC 03 45 0C 8D 50 01 8A 01 3A 02 73 30 8B 45 FC 03 45 0C 8A 00 88 45 FB 8B 45 FC 8B 55 0C 01 C2 8B 45 FC 03 45 0C 40 8A 00 88 02 8B 45 FC 03 45 0C 8D 50 01 8A 45 FB 88 02 C6 45 FA 00 8D 45 FC FF 00 EB A7 C9 C2 0C 00 90 90 90 90 90 90 is loaded into memory and executed using the following method snippet var MySrcArray, MyDestArray: array [1 .. 15] of Byte; // ... MyBuffer: Pointer; TheProc: procedure; SortIt: procedure(ASrc, ADest: Pointer; ASize: LongWord); stdcall; begin // Initialization of MySrcArray with random Bytes and display here ... // Instructions of loading of the binary file into MyBuffer using merely **GetMem** here ... @SortIt := MyBuffer; try SortIt(@MySrcArray, @MyDestArray, 15); // Display of MyDestArray (The outcome of the processing !) except // Invalid code error handling end; // Cleaning code here ... end; works like a charm on my box. My Question: How comes it works without using VirtualAlloc and/or VirtualProtect?

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  • Update C# Chart using BackgroundWorker

    - by Mark
    I am currently trying to update a chart which is on my form to the background worker using: bwCharter.RunWorkerAsync(chart1); Which runs: private void bcCharter_DoWork(object sender, DoWorkEventArgs e) { System.Windows.Forms.DataVisualization.Charting.Chart chart = null; // Convert e.Argument to chart //.. // Converted.. chart.Series.Clear(); e.Result=chart; setChart(c.chart); } private void setChart(System.Windows.Forms.DataVisualization.Charting.Chart arg) { if (chart1.InvokeRequired) { chart1.Invoke(new MethodInvoker(delegate { setChart(arg); })); return; } chart1 = arg; } However, at the point of clearing the series, an exception is thrown. Basically, I want to do a whole lot more processing after clearing the series, which slows the GUI down completely - so wanted this in another thread. I thought that by passing it as an argument, I should be safe, but apparently not! Interestingly, the chart is on a tab page. I can run this over and over if the tabpage is in the background, but if I run this, look at the chart, hide it again, and re-run, it throws the exception. Obviously, it throws if the chart is in the foreground as well. Can anyone suggest what I can do differently? Thanks!

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  • what's wrong with my producer-consumer queue design?

    - by toasteroven
    I'm starting with the C# code example here. I'm trying to adapt it for a couple reasons: 1) in my scenario, all tasks will be put in the queue up-front before consumers will start, and 2) I wanted to abstract the worker into a separate class instead of having raw Thread members within the WorkerQueue class. My queue doesn't seem to dispose of itself though, it just hangs, and when I break in Visual Studio it's stuck on the _th.Join() line for WorkerThread #1. Also, is there a better way to organize this? Something about exposing the WaitOne() and Join() methods seems wrong, but I couldn't think of an appropriate way to let the WorkerThread interact with the queue. Also, an aside - if I call q.Start(#) at the top of the using block, only some of the threads every kick in (e.g. threads 1, 2, and 8 process every task). Why is this? Is it a race condition of some sort, or am I doing something wrong? using System; using System.Collections.Generic; using System.Text; using System.Messaging; using System.Threading; using System.Linq; namespace QueueTest { class Program { static void Main(string[] args) { using (WorkQueue q = new WorkQueue()) { q.Finished += new Action(delegate { Console.WriteLine("All jobs finished"); }); Random r = new Random(); foreach (int i in Enumerable.Range(1, 10)) q.Enqueue(r.Next(100, 500)); Console.WriteLine("All jobs queued"); q.Start(8); } } } class WorkQueue : IDisposable { private Queue _jobs = new Queue(); private int _job_count; private EventWaitHandle _wh = new AutoResetEvent(false); private object _lock = new object(); private List _th; public event Action Finished; public WorkQueue() { } public void Start(int num_threads) { _job_count = _jobs.Count; _th = new List(num_threads); foreach (int i in Enumerable.Range(1, num_threads)) { _th.Add(new WorkerThread(i, this)); _th[_th.Count - 1].JobFinished += new Action(WorkQueue_JobFinished); } } void WorkQueue_JobFinished(int obj) { lock (_lock) { _job_count--; if (_job_count == 0 && Finished != null) Finished(); } } public void Enqueue(int job) { lock (_lock) _jobs.Enqueue(job); _wh.Set(); } public void Dispose() { Enqueue(Int32.MinValue); _th.ForEach(th = th.Join()); _wh.Close(); } public int GetNextJob() { lock (_lock) { if (_jobs.Count 0) return _jobs.Dequeue(); else return Int32.MinValue; } } public void WaitOne() { _wh.WaitOne(); } } class WorkerThread { private Thread _th; private WorkQueue _q; private int _i; public event Action JobFinished; public WorkerThread(int i, WorkQueue q) { _i = i; _q = q; _th = new Thread(DoWork); _th.Start(); } public void Join() { _th.Join(); } private void DoWork() { while (true) { int job = _q.GetNextJob(); if (job != Int32.MinValue) { Console.WriteLine("Thread {0} Got job {1}", _i, job); Thread.Sleep(job * 10); // in reality would to actual work here if (JobFinished != null) JobFinished(job); } else { Console.WriteLine("Thread {0} no job available", _i); _q.WaitOne(); } } } } }

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  • Yet another "What is this code doing"-type of Perl code

    - by Mike
    I have inherited some code from a guy whose favorite past time was to shorten every line to its absolute minimum (and sometimes only to make it look cool). His code is hard to understand but I managed to understand (and rewrite) most of it. Now I have stumbled on a piece of code which, no matter how hard I try, I cannot understand. my @heads = grep {s/\.txt$//} OSA::Fast::IO::Ls->ls($SysKey,'fo','osr/tiparlo',qr{^\d+\.txt$}) || (); my @selected_heads = (); for my $i (0..1) { $selected_heads[$i] = int rand scalar @heads; for my $j (0..@heads-1) { last if (!grep $j eq $_, @selected_heads[0..$i-1]); $selected_heads[$i] = ($selected_heads[$i] + 1) % @heads; #WTF? } my $head_nr = sprintf "%04d", $i; OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].txt","$recdir/heads/$head_nr.txt"); OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].cache","$recdir/heads/$head_nr.cache"); } From what I can understand, this is supposed to be some kind of randomizer, but I never saw a more complex way to achieve randomness. Or are my assumptions wrong? At least, that's what this code is supposed to do. Select 2 random files and copy them. === NOTES === The OSA Framework is a Framework of our own. They are named after their UNIX counterparts and do some basic testing so that the application does not need to bother with that.

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  • Yet another Haskell vs. Scala question

    - by Travis Brown
    I've been using Haskell for several months, and I love it—it's gradually become my tool of choice for everything from one-off file renaming scripts to larger XML processing programs. I'm definitely still a beginner, but I'm starting to feel comfortable with the language and the basics of the theory behind it. I'm a lowly graduate student in the humanities, so I'm not under a lot of institutional or administrative pressure to use specific tools for my work. It would be convenient for me in many ways, however, to switch to Scala (or Clojure). Most of the NLP and machine learning libraries that I work with on a daily basis (and that I've written in the past) are Java-based, and the primary project I'm working for uses a Java application server. I've been mostly disappointed by my initial interactions with Scala. Many aspects of the syntax (partial application, for example) still feel clunky to me compared to Haskell, and I miss libraries like Parsec and HXT and QuickCheck. I'm familiar with the advantages of the JVM platform, so practical questions like this one don't really help me. What I'm looking for is a motivational argument for moving to Scala. What does it do (that Haskell doesn't) that's really cool? What makes it fun or challenging or life-changing? Why should I get excited about writing it?

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  • Passing array values in an HTTP request in .NET

    - by Zarjay
    What's the standard way of passing and processing an array in an HTTP request in .NET? I have a solution, but I don't know if it's the best approach. Here's my solution: <form action="myhandler.ashx" method="post"> <input type="checkbox" name="user" value="Aaron" /> <input type="checkbox" name="user" value="Bobby" /> <input type="checkbox" name="user" value="Jimmy" /> <input type="checkbox" name="user" value="Kelly" /> <input type="checkbox" name="user" value="Simon" /> <input type="checkbox" name="user" value="TJ" /> <input type="submit" value="Submit" /> </form> The ASHX handler receives the "user" parameter as a comma-delimited string. You can get the values easily by splitting the string: public void ProcessRequest(HttpContext context) { string[] users = context.Request.Form["user"].Split(','); } So, I already have an answer to my problem: assign multiple values to the same parameter name, assume the ASHX handler receives it as a comma-delimited string, and split the string. My question is whether or not this is how it's typically done in .NET. What's the standard practice for this? Is there a simpler way to grab the multiple values than assuming that the value is comma-delimited and calling Split() on it? Is this how arrays are typically passed in .NET, or is XML used instead? Does anyone have any insight on whether or not this is the best approach?

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  • Updating a local sqlite db that is used for local metadata & caching from an service?

    - by Pharaun
    I've searched through the site and haven't found a question/answer that quite answer my question, the closest one I found was: Syncing objects between two disparate systems best approach. Anyway to begun, because there is no RSS feeds available, I'm screen scrapping a webpage, hence it does a fetch then it goes through the webpage to scrap out all of the information that I'm interested in and dumps that information into a sqlite database so that I can query the information at my leisure without doing repeat fetching from the website. However I'm also storing various metadata on the data itself that is stored in the sqlite db, such as: have I looked at the data, is the data new/old, bookmark to a chunk of data (Think of it as a collection of unrelated data, and the bookmark is just a pointer to where I am in processing/reading of the said data). So right now my current problem is trying to figure out how to update the local sqlite database with new data and/or changed data from the website in a manner that is effective and straightforward. Here's my current idea: Download the page itself Create a temporary table for the parsed data to go into Do a comparison between the official and the temporary table and copy updates and/or new information to the official table This process seems kind of complicated because I would have to figure out how to determine if the data in the temporary table is new, updated, or unchanged. So I am wondering if there isn't a better approach or if anyone has any suggestion on how to architecture/structure such system?

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