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  • Whats the point of STL?

    - by Jonathan D
    I've been programming c++ for about a year now and when i'm looking about i see lots of references to STL. Can some one please tell me what it does? and the advantages and disadvantageous of it? thanks

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  • EXC_BAD_ACCESS on [error localizedDescription];

    - by david
    This Code trows an EXC_BAD_ACCESS: NSError* error; if(![appdelegate.managedObjectContext countForFetchRequest:request error:&error]) { DLog(@"Failed to save to data store: %@", [error localizedDescription]); NSArray* detailedErrors = [[error userInfo] objectForKey:NSDetailedErrorsKey]; if(detailedErrors != nil && [detailedErrors count] > 0) { for(NSError* detailedError in detailedErrors) { DLog(@" DetailedError: %@", [detailedError userInfo]); } } else { DLog(@" %@", [error userInfo]); } }

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  • How can I write classes that don't rely on "global" variables?

    - by Joel
    When I took my first programming course in university, we were taught that global variables were evil & should be avoided at all cost (since you can quickly develop confusing and unmaintainable code). The following year, we were taught object oriented programming, and how to create modular code using classes. I find that whenever I work with OOP, I use my classes' private variables as global variables, i.e., they can be (and are) read and modified by any function within the class. This isn't really sitting right with me, as it seems to introduce the same problems global variables had in languages like C. So I guess my question is, how do I stop writing classes with "global" variables? Would it make more sense to pretend I'm writing in a functional language? By this I mean having all functions take parameters & return values instead of directly modifying class variables. If I need to set any fields, I can just take the output of the function and assign it instead of having the function do it directly. This seems like it might make more maintainable code, at least for larger classes. What's common practice? Thanks!

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  • C# integer primary key generation using Entity Framework with local database file (Sdf)

    - by Ronny
    Hello, I'm writing a standalone application and I thought using Entity Framework to store my data. At the moment the application is small so I can use a local database file to get started. The thing is that the local database file doesn't have the ability to auto generate integer primary keys as SQL Server does. Any suggestions how to manage primary keys for entities in a local database file that will be compatible with SQL Server in the future? Thanks, Ronny

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  • How to handle BL cache for multiple web applications?

    - by Eran Betzalel
    I recently received a project that contains multiple web applications with no MVC structure. For starters I've created a library (DLL) that will contain the main Business Logic. The problem is with Caching - If I use the current web context cache object than I might end up with duplicate caching (as the web context will be different for every application). I'm currently thinking about implementing a simple caching mechanism with a singleton pattern that will allow the different web sites (aka different application domains) to share their "caching wisdom". I'd like to know what is the best way to solve this problem.

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  • How to: mirror a staging server from a production server

    - by Zombies
    We want to mirror our current production app server (Oracle Application Server) onto our staging server. As it stands right now, various things are out of sync, and what may work in testing/QA can easily fail in production because of settings/patch/etc inconsistencies. I was thinking what would be best is to clone the entire disk daily and push it onto the staging server... Would this be the best method...?

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  • Objective C -std=c99 usage

    - by Andy White
    Is there any reason why you shouldn't use the "-std=c99" flag for compiling Objective-C programs on Mac? The one feature in C99 that I really like is the ability to declare variables anywhere in code, rather than just at the top of methods, but does this flag causes any problems or create incompatibilities for iPhone or Cocoa apps?

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  • hover effect jQuery

    - by Ori Cohen
    I have a bunch of li elements that I want to alternate in color using odds and evens, and then highlight based on mouse hover. In order to un-highlight I need to keep track of what the color used to be, odd or even. To do this when I apply the highlight color, I first set an arbitrary attribute to it. Are there any downsides to doing it this way? Is there a better way? Here's the code: <script type="text/javascript"> var init = function(event){ $("li:odd").css({'background-color' : '#eeeeee', 'font-weight' : 'bold'}); $("li:even").css('background-color', '#cccccc'); //initial colors setup $("li").hover( function () //hover over { var current = $(this); current.attr('old-background', current.css('background-color')); current.css('background-color', '#ffee99'); } , function() //hover out { var current = $(this); current.css('background-color', current.attr('old-background')); }) } $(document).ready(init); </script> So is there a better way to do this?

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  • Ways std::stringstream can set fail/bad bit?

    - by Evan Teran
    A common piece of code I use for simple string splitting looks like this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } return elems; } Someone mentioned that this will silently "swallow" errors occurring in std::getline. And of course I agree that's the case. But it occurred to me, what could possibly go wrong here in practice that I would need to worry about. basically it all boils down to this: inline std::vector<std::string> split(const std::string &s, char delim) { std::vector<std::string> elems; std::stringstream ss(s); std::string item; while(std::getline(ss, item, delim)) { elems.push_back(item); } if(ss.fail()) { // *** How did we get here!? *** } return elems; } A stringstream is backed by a string, so we don't have to worry about any of the issues associated with reading from a file. There is no type conversion going on here since getline simply reads until it sees a newline or EOF. So we can't get any of the errors that something like boost::lexical_cast has to worry about. I simply can't think of something besides failing to allocate enough memory that could go wrong, but that'll just throw a std::bad_alloc well before the std::getline even takes place. What am I missing?

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  • jQuery global variable best practice & options?

    - by Kris Krause
    Currently I am working on a legacy web page that uses a ton of javascript, jquery, microsoft client javascript, and other libraries. The bottom line - I cannot rewrite the entire page from scratch as the business cannot justify it. So... it is what it is. Anyway, I need to pollute (I really tried not too) the global namespace with a variable. There are the three options I was thinking - Just store/retrieve it using a normal javascript declaration - var x = 0; Utilize jQuery to store/retrieve the value in a DOM tag - $("body").data("x", 0); Utilize a hidden form field, and set/retrieve the value with jQuery - $("whatever").data("x", 0); What does everyone think? Is there a better way? I looked at the existing pile of code and I do not believe the variable can be scoped in a function.

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  • NSZombieEnabled breaking working code?

    - by Gordon Fontenot
    I have the following method in UIImageManipulation.m: +(UIImage *)scaleImage:(UIImage *)source toSize:(CGSize)size { UIImage *scaledImage = nil; if (source != nil) { UIGraphicsBeginImageContext(size); [source drawInRect:CGRectMake(0, 0, size.width, size.height)]; scaledImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); } return scaledImage; } I am calling it in a different view with: imageFromFile = [UIImageManipulator scaleImage:imageFromFile toSize:imageView.frame.size]; (imageView is a UIImageView allocated earlier) This is working great in my code. I resizes the image perfectly, and throws zero errors. I also don't have anything pop up under build - analyze. But the second I turn on NSZombieEnabled to debug a different EXC_BAD_ACCESS issue, the code breaks. Every single time. I can turn NSZombieEnabled off, code runs great. I turn it on, and boom. Broken. I comment out the call, and it works again. Every single time, it gives me an error in the console: -[UIImage release]: message sent to deallocated instance 0x3b1d600. This error doesn't appear if `NSZombieEnabled is turned off. Any ideas? --EDIT-- Ok, This is killing me. I have stuck breakpoints everywhere I can, and I still cannot get a hold of this thing. Here is the full code when I call the scaleImage method: -(void)setupImageButton { UIImage *imageFromFile; if (object.imageAttribute == nil) { imageFromFile = [UIImage imageNamed:@"no-image.png"]; } else { imageFromFile = object.imageAttribute; } UIImage *scaledImage = [UIImageManipulator scaleImage:imageFromFile toSize:imageButton.frame.size]; UIImage *roundedImage = [UIImageManipulator makeRoundCornerImage:scaledImage :10 :10 withBorder:YES]; [imageButton setBackgroundImage:roundedImage forState:UIControlStateNormal]; } The other UIImageManipulator method (makeRoundCornerImage) shouldn't be causing the error, but just in case I'm overlooking something, I threw the entire file up on github here. It's something about this method though. Has to be. If I comment it out, it works great. If I leave it in, Error. But it doesn't throw errors with NSZombieEnabled turned off ever.

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  • AVAudioPlayer crash after playing from an AVAudioRecord

    - by munchine
    I've got a button the user tap to start recording and tap again to stop. When it stop I want the recorded voice 'echo' back so the user can hear what was recorded. This works fine the first time. If I hit the button for the third time, it starts a new recording and when I hit stop it crashes with EXC_BAD_ACCESS. - (IBAction) readToMeTapped { if(recording) { recording = NO; [readToMeButton setTitle:@"Stop Recording" forState: UIControlStateNormal ]; NSMutableDictionary *recordSetting = [[NSDictionary alloc] initWithObjectsAndKeys: [NSNumber numberWithFloat: 44100.0], AVSampleRateKey, [NSNumber numberWithInt: kAudioFormatAppleLossless], AVFormatIDKey, [NSNumber numberWithInt: 1], AVNumberOfChannelsKey, [NSNumber numberWithInt: AVAudioQualityMax], AVEncoderAudioQualityKey, nil]; // Create a new dated file NSDate *now = [NSDate dateWithTimeIntervalSinceNow:0]; NSString *caldate = [now description]; recordedTmpFile = [NSURL fileURLWithPath:[[NSString stringWithFormat:@"%@/%@.caf", DOCUMENTS_FOLDER, caldate] retain]]; error = nil; recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error]; if(!recorder){ NSLog(@"recorder: %@ %d %@", [error domain], [error code], [[error userInfo] description]); UIAlertView *alert = [[UIAlertView alloc] initWithTitle: @"Warning" message: [error localizedDescription] delegate: nil cancelButtonTitle:@"OK" otherButtonTitles:nil]; [alert show]; [alert release]; return; } NSLog(@"Using File called: %@",recordedTmpFile); //Setup the recorder to use this file and record to it. [recorder setDelegate:self]; [recorder prepareToRecord]; [recorder recordForDuration:(NSTimeInterval) 5]; //recording for a limited time } else { // it crashes the second time it gets here! recording = YES; NSLog(@"Recording YES Using File called: %@",recordedTmpFile); [readToMeButton setTitle:@"Start Recording" forState:UIControlStateNormal ]; [recorder stop]; //Stop the recorder. //playback recording AVAudioPlayer * newPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:recordedTmpFile error:&error]; [recordedTmpFile release]; self.aPlayer = newPlayer; [newPlayer release]; [aPlayer setDelegate:self]; [aPlayer prepareToPlay]; [aPlayer play]; } } - (void)audioRecorderDidFinishRecording:(AVAudioRecorder *)sender successfully:(BOOL)flag { NSLog (@"audioRecorderDidFinishRecording:successfully:"); [recorder release]; recorder = nil; } Checking the debugger, it flags the error here @synthesize aPlayer, recorder; This is the part I don't understand. I thought it may have something to do with releasing memory but I've been careful. Have I missed something?

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  • Avoiding EXC_BAD_ACCESS when using the delegate pattern

    - by Kenny Winker
    A have a view controller, and it creates a "downloader" object, which has a reference to the view controller (as a delegate). The downloader calls back the view controller if it successfully downloads the item. This works fine as long as you stay on the view, but if you navigate away before the download is complete I get EXC_BAD_ACCESS. I understand why this is happening, but is there any way to check if an object is still allocated? I tried to test using delegate != nil, and [delegate respondsToSelector:], but it chokes. if (!self.delegate || ![self.delegate respondsToSelector:@selector(downloadComplete:)]) { // delegate is gone, go away quietly [self autorelease]; return; } else { // delegate is still around [self.delegate downloadComplete:result]; } I know I could, a) have the downloader objects retain the view controller b) keep an array of downloaders in the view controller, and set their delegate values to nil when I deallocate the view controller. But I wonder if there is an easier way, where I just test if the delegate address contains a valid object?

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  • jQuery plug-in with additional methods.

    - by Kieron
    I've a jQuery plug-in that operates on some ULs, adding and removing classes etc. During the life-cycle of the page, I'll need to add/ remove some classes in code, and as my plug-in needs to perform some additional operations when this happens I came up with the following: // This is the initialiser method... $.fn.objectBuilder = function (options) {...}; // These are the two new methods I need. $.fn.objectBuilder.setSelected(element) {...}; $.fn.objectBuilder.removeSelected() {...}; I'd then like to call them like this: $("#ob1").objectbuilder.removeSelected(); Any thoughts? Thanks, Kieron edit I suppose what I'm asking is, whats the best way of adding additional methods to a jQuery plug-in where it'll have access to the root object, in this case #obj when the method is called.

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  • Break on EXC_BAD_ACCESS in XCode?

    - by jasonh
    I'm new to iPhone development and XCode in general and have no idea how to begin troubleshooting an EXC_BAD_ACCESS signal. How can I get XCode to break at the exact line that is causing the error? I can't seem to get XCode to stop on the line causing the problem, but I do see the following lines in my debug console: Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextSetStrokeColorWithColor: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextSetLineWidth: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextAddPath: invalid context Sun Oct 25 15:12:14 jasonsmacbook TestProject[1289] : CGContextDrawPath: invalid context 2009-10-25 15:12:14.680 LanderTest[1289:207] *** -[CFArray objectAtIndex:]: message sent to deallocated instance 0x3c4e610 Now, I am attempting to draw to the context I retrieve from UIGraphicsGetCurrentContext() and pass to the object that I want to draw with. Further trial and error debugging and I found that an NSMutableArray I have a property for on my class was a zombie. I went into the init function for the class and here's the code I was using: if ((self = [super init])) { NSMutableArray *array = [NSMutableArray array]; self.terrainBlocks = array; [array release]; } return self; } I removed the [array release] line and it no longer gives me the EXC_BAD_ACCESS signal, but I'm now confused about why this works. I thought that when I used the property, it automatically retained it for me, and thus I should release it from within init so that I don't have a leak. I'm thoroughly confused about how this works and all the guides and Stackoverflow questions I've read only confuse me more about how to set properties within my init method. There seems to be no consensus as to which way is the best.

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  • Implementing IDisposable on a subclass when the parent also implements IDisposable

    - by Tanzelax
    I have a parent and child class that both need to implement IDisposable. Where should virtual (and base.Dispose()?) calls come into play? When I just override the Dispose(bool disposing) call, it feels really strange stating that I implement IDisposable without having an explicit Dispose() function (just utilizing the inherited one), but having everything else. What I had been doing (trivialized quite a bit): internal class FooBase : IDisposable { Socket baseSocket; private void SendNormalShutdown() { } public void Dispose() { Dispose(true); GC.SuppressFinalize(this); } private bool _disposed = false; protected virtual void Dispose(bool disposing) { if (!_disposed) { if (disposing) { SendNormalShutdown(); } baseSocket.Close(); } } ~FooBase() { Dispose(false); } } internal class Foo : FooBase, IDisposable { Socket extraSocket; private bool _disposed = false; protected override void Dispose(bool disposing) { if (!_disposed) { extraSocket.Close(); } base.Dispose(disposing); } ~Foo() { Dispose(false); } }

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  • What is the best way to update an unattached entity on Entity Framework?

    - by Carlos Loth
    Hi, In my project I have some data classes to retrieve data from the database using the Entity Framework. We called these classes *EntityName*Manager. All of them have a method to retrieve entities from database and they behave most like this: static public EntityA SelectByName(String name) { using (var context = new ApplicationContext()) { var query = from a in context.EntityASet where a.Name == name select a; try { var entityA = query.First(); context.Detach(entityA); return entityA; } catch (InvalidOperationException ex) { throw new DataLayerException( String.Format("The entityA whose name is '{0}' was not found.", name), ex); } } } You can see that I detach the entity before return it to the method caller. So, my question is "what is the best way to create an update method on my *EntityA*Manager class?" I'd like to pass the modified entity as a parameter of the method. But I haven't figured out a way of doing it without going to the database and reload the entity and update its values inside a new context. Any ideas? Thanks in advance, Carlos Loth.

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  • Proper way to use a config file?

    - by user156814
    I just started using a PHP framework, Kohana (V2.3.4) and I am trying to set up a config file for each of my controllers. I never used a framework before, so obviously Kohana is new to me. I was wondering how I should set up my controllers to read my config file. For example, I have an article controller and a config file for that controller. I have 3 ways of loading config settings // config/article.php $config = array( 'display_limit' => 25, // limit of articles to list 'comment_display_limit' => 20, // limit of comments to list for each article // other things ); Should I A) Load everything into an array of settings // set a config array class article_controller extends controller{ public $config = array(); function __construct(){ $this->config = Kohana::config('article'); } } B) Load and set each setting as its own property // set each config as a property class article_controller extends controller{ public $display_limit; public $comment_display_limit; function __construct(){ $config = Kohana::config('article'); foreach ($config as $key => $value){ $this->$key = $value; } } } C) Load each setting only when needed // load config settings only when needed class article_controller extends controller{ function __construct(){} // list all articles function show_all(){ $display_limit = Kohana:;config('article.display_limit'); } // list article, with all comments function show($id = 0){ $comment_display)limit = Kohana:;config('article.comment_display_limit'); } } Note: Kohana::config() returns an array of items. Thanks

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  • Hyphens or underscores in CSS and HTML identifiers?

    - by Török Gábor
    As both hyphen (-) and underscore (_) are valid characters in CSS and HTML identifiers, what are the advantages and disadvantages using one or the other? I prefer writing CSS class names with hyphens (e.g. field-text) and underscores for IDs (e.g. featured_content). Is there a best practice or it's only the matter of taste?

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  • Creative ways to punish (or just curb) laziness in coworkers

    - by FerretallicA
    Like the subject suggests, what are some creative ways to curb laziness in co-workers? By laziness I'm talking about things like using variable names like "inttheemplrcd" instead of "intEmployerCode" or not keeping their projects synced with SVN, not just people who use the last of the sugar in the coffee room and don't refill the jar. So far the two most effective things I've done both involve the core library my company uses. Since most of our programs are in VB.net the lack of case sensitivity is abused a lot. I've got certain features of the library using Reflection to access data in the client apps, which has a negligible performance hit and introduces case sensitivity in a lot places where it is used. In instances where we have an agreed standard which is compromised by blatant laziness I take it a step further, like the DatabaseController class which will blatantly reject any DataTable passed to it which isn't named dtSomething (ie- must begin with dt and third letter must be capitalised). It's frustrating to have to resort to things like this but it has also gradually helped drill more attention to detail into their heads. Another is adding some code to the library's initialisation function to display a big and potentially embarrassing (only if seen by a client) message advising that the program is running in debug mode. We have had many instances where projects are sent to clients built in debug mode which has a lot of implications for us (especially with regard to error recovery) and doing that has made sure they always build to release before distributing. Any other creative (ie- not StyleCop etc) approaches like this?

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  • Convert methods from Java-actionscript to ObjectiveC

    - by eco_bach
    Hi I'm tring to convert the following 3 methods from java-actionscript to Objective C. Part of my confusion I think is not knowing what Number types, primitives I should be using. ie in actionscript you have only Number, int, and uint. These are the 3 functions I am trying to convert public function normalize(value:Number, minimum:Number, maximum:Number):Number { return (value - minimum) / (maximum - minimum); } public function interpolate(normValue:Number, minimum:Number, maximum:Number):Number { return minimum + (maximum - minimum) * normValue; } public function map(value:Number, min1:Number, max1:Number, min2:Number, max2:Number):Number { return interpolate( normalize(value, min1, max1), min2, max2); } This is what I have so far -(float) normalize:(float*)value withMinimumValue:(float*)minimum withMaximumValue:(float*)maximum { return (value - minimum) / (maximum - minimum); } -(float) interpolate:(float*)normValue withMinimumValue:(float*)minimum withMaximumValue:(float*)maximum { return minimum + (maximum - minimum) * normValue; } -(float) map:(float*)value withMinimumValue1:(float*)min1 withMaximumValue1:(float*)max1 withMinimumValue2:(float*)min2 withMaximumValue2:(float*)max2 { return interpolate( normalize(value, min1, max1), min2, max2); }

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  • Views performance in MySQL for denormalization

    - by Gianluca Bargelli
    I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role). EDIT Specifically what i'm trying to obtain is Denormalization of three tables into one. Is my solution correct? See Denormalization on wikipedia

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  • Catching java.lang.OutOfMemoryError

    - by dotsid
    Documentation for java.lang.Error says: An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch But as java.lang.Error is subclass of java.lang.Throwable I can catch this type of throwable. I understand why this is not good idea to catch this sort of exceptions. As far as I understand, if we decide to caught it, the catch handler should not allocate any memory by itself. Otherwise OutOfMemoryError will be thrown again. So, my question is: is there any real word scenarios when catching java.lang.OutOfMemoryError may be a good idea? if we catching java.lang.OutOfMemoryError how can we sure that catch handler doesn't allocate any memory by itself (any tools or best practicies)? Thanks a lot.

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