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  • Memory management technique for Objective-C iVars/properties

    - by David Rea
    Is the following code doing anything unnecessary? @interface MyClass { NSArray *myArray; } -(void)replaceArray:(NSArray *)newArray; @implementation MyClass -(void)replaceArray:(NSArray *)newArray { if( myArray ) { [myArray release]; myArray = nil; } myArray = [[NSArray alloc] initWithArray: newArray]; } @end What if I made the following changes: 1) Made myArray a property: @property (nonatomic, retain) NSArray myArray; 2) Changed the assignment to: self.myArray = [NSArray arrayWithArray: newArray]; Would that allow me to remove the conditional?

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  • If .net sha1 hash expects a byte array, and php sha1() wants a string, can I match the results?

    - by lynn
    I have a set of bytes I want to apply an sha1 hash to. One hash will be in .net, the other in PHP. Then I'll test to see if they match. In .net, you can create a byte array and use sha.ComputeHash(). byte[] data = new byte[DATA_SIZE]; byte[] result; SHA1 sha = new SHA1CryptoServiceProvider(); // This is one implementation of the abstract class SHA1. result = sha.ComputeHash(data); In PHP, you call sha1($string). I can't do anything about the .net side of the code, but how can I get the same hash out of PHP that .net will generate? Please note: I am ONLY able to work on the PHP side of this. The .net stuff is fixed and can't be modified. Thanks!

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  • Android NDK R5 and support of C++ exception

    - by plaisthos
    Hi, I am trying to use the NDK 5 full C++ gnustl: sources/cxx-stl/gnu-libstdc++/README states: This implementation fully supports C++ exceptions and RTTI. But all attempts using exceptions fail. An alternative NDK exists on http://www.crystax.net/android/ndk-r4.php. Even the hello-jni example from that site does not work. Compliation works after creating an Application.xml with APP_STL := gnustl_static But it dies the same horrific death as my own experiments. Am I am missing something or is the statement in the README just plain wrong?

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  • Java/MySQL: Working with data in classes

    - by skiwi
    What is the best way to deal with accessing/modifying tables in a database? I have read about the Data Access Object approach, but none of the resources I have found so far indicate a clear implementation of it. So assume you have a database with a table called accounts that has columns id, name, password and email. How would you properly access it within Java? I mean most people know how to do SQL statements, but that is not really the point. I hope people here can be of help. Regards.

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  • How to implement arrays in an interpreter?

    - by Ray
    I have managed to write several interpreters including Tokenizing Parsing, including more complicated expressions such as ((x+y)*z)/2 Building bytecode from syntax trees Actual bytecode execution What I didn't manage: Implementation of dictionaries/lists/arrays. I always got stuck with getting multiple values into one variable. My value structure (used for all values passed around, including variables) looks like this, for example: class Value { public: ValueType type; int integerValue; string stringValue; } Works fine with integers and strings, but how could I implement arrays? (From now on with array I mean arrays in my experimental language, not in C++) How can I fit the array concept into the Value class above? Is it possible? How should I make arrays able to be passed around just as you could pass around integers and strings in my language, using the class above? Accessing array elements or memory allocation wouldn't be the problem, I just don't know how to store them.

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  • Java Program Design Layout Recommendations?

    - by Leebuntu
    I've learned enough to begin writing programs from scratch, but I'm running into the problem of not knowing how to design the layout and implementation of a program. To be more precise, I'm having difficulty finding a good way to come up with an action plan before I dive in to the programming part. I really want to know what classes, methods, and objects I would need beforehand instead of just adding them along the way. My intuition is leading me to using some kind of charting software that gives a hierarchal view of all the classes and methods. I've been using OmniGraffle Pro and while it does seem to work somewhat, I'm still having trouble planning out the program in its entirety. How should I approach this problem? What softwares out there are available to help with this problem? Any good reads out there on this issue? Thanks so much! Edit: Oh yeah, I'm using Eclipse and I code mainly in Java right now.

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  • Programming for a 32-bit environment vs programming for a 64-bit environment / Build configurations

    - by Russel
    I was looking at some same code (a sample MS Visual Studio C++ project) recently with multiple build configurations (Release/Debug, Win32/x64). My question: What is the difference? I guess I understand Release/Debug (Release = finalized version of project, Debug = version used to run in debugger), but what things need to be considered when building different versions for Win32/x64 platforms? Is there any coding differences, or does this just affect how that same code is ultimately built into machine code? I know there are different library files depending on whether you're using a 32-bit or 64-bit system as well... Are all of these differences again just machine code? Would a 32-bit library file and its corresponding 64-bit library file be two files with exactly the same functions build from the same source code originally, and only differing in their machine code implementation? Thanks! --Russel

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  • What's the correct way to stop a background process on Mac OS X?

    - by mcsheffrey
    I have an application with 2 components: a desktop application that users interact with, and a background process that can be enabled from the desktop application. Once the background process is enabled, it will run as a user launch agent independently of the desktop app. However, what I'm wondering is what to do when the user disables the background process. At this point I want to stop the background process but I'm not sure what the best approach is. The 3 options that I see are: Use the 'kill' command. Direct, but not reliable and just seems somewhat "wrong". Use an NSMachPort to send an exit request from the desktop app to the background process. This is the best approach I've thought of but I've run into an implementation problem (I'll be posting this in a separate query) and I'd like to be sure that the approach is right before going much further. Something else??? Thank you in advance for any help/insight that you can offer.

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  • Implementing DRY Forms

    - by virtualeyes
    Getting into Play 2.0, overall, blown away, great stuff. Anyway, wondering how one can achieve DRY forms in Play? If you look at the create & edit examples in the Computer Database Sample, you'll see that the form elements are repeated. With just 4 fields (in the sample form), no big deal, but when you're dealing with large, complex forms and/or handling many CRUD models, the duplication becomes a bigger maintenance issue. On the binding end ( form.bindFromRequest and form.fill(Foo) ), the implementation is so elegant for create/edit operations; is there a corresponding solution in the template layer?

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  • What's a good way to detect wrap-around in a fixed-width message counter?

    - by Kristo
    I'm writing a client application to communicate with a server program via UDP. The client periodically makes requests for data and needs to use the most recent server response. The request message has a 16-bit unsigned counter field that is echoed by the server so I can pair requests with server responses. Since it's UDP, I have to handle the case where server responses arrive out of order (or don't arrive at all). Naively, that means holding on to the highest message counter seen so far and dropping any incoming message with a lower number. But that will fail as soon as we pass 65535 messages and the counter wraps back to zero. Is there a good way to detect (with reasonable probability) that, for example, message 5 actually comes after message 65,000? The implementation language is C++.

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  • iPhone noob - different method types?

    - by codemonkey
    My apologies in advance for what is probably a really dumb question. I'm familiar (or at least getting familiar) with instance and class methods in objective-c, but have also seen method implementations that look like this: #import "Utilities.h" #import "CHAPPAppDelegate.h" #import "AppState.h" @implementation Utilities CHAPPAppDelegate* GetAppDelegate() { return (CHAPPAppDelegate *)[UIApplication sharedApplication].delegate; } AppState* GetAppState() { return [GetAppDelegate() appState]; } @end What are these? While I'm sure this is documented somewhere, I don't know what term to use in searching for an explanation of what's being done here. I like the syntax methods like this let me use when calling them, but I'm not sure exactly what I'm doing, what the implications are, how to send parameters to these types of functions, etc? To clarify how I ended up in this position, I started using these methods in a "utilities" class of mine after reading some online blog describing the author's preference for declaring these functions this way. Now I can't seem to track down a more detailed explanation of what exactly the differences are, etc.

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  • Is there a way to determine the Variance of an Interface / Delegate in C# 4.0?

    - by BFree
    So now that we have generic Covariance and Contravariance on interfaces and delegates in C#, I was just curious if given a Type, you can figure out the covariance/contravariance of its generic arguments. I started trying to write my own implementation, which would look through all of the methods on a given type and see if the return types and or arguments match the types in the generic arguments. The problem is that even if I have this: public interface IFoo<T> { void DoSomething(T item); } using my logic, it LOOKS like it should be contravariant, but since we didn't actually specify: public interface IFoo<in T> { void DoSomething(T item); } (the in parameter) it isn't actually contravariant. Which leads to my question: Is there a way to determine the variance of generic parameters?

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  • How to increment a value using a C-Preprocessor in Objective-C?

    - by mystify
    Example: I try to do this: static NSInteger stepNum = 1; #define METHODNAME(i) -(void)step##i #define STEP METHODNAME(stepNum++) @implementation Test STEP { // do stuff... [self nextFrame:@selector(step2) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step3) afterDelay:1]; } STEP { // do stuff... [self nextFrame:@selector(step4) afterDelay:1]; } // ... When building, Xcode complains that it can't increment stepNum. This seems logical to me, because at this time the code is not "alive" and this pre-processing substitution stuff happens before actually compiling the source code. Is there another way I could have an variable be incremented on every usage of STEP macro, the easy way?

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  • PHP Doxygen Collaboration Diagrams

    - by Shabbyrobe
    I've started playing around with doxygen to generate documentation from my PHP code. I notice there are two diagrams in the generated output - inheritance and collaboration. I know about the inheritance one, but the collaboration one has piqued my interest since reading the manual: If the COLLABORATION_GRAPH and HAVE_DOT tags are set to YES then doxygen will generate a graph for each documented class showing the direct and indirect implementation dependencies (inheritance, containment, and class references variables) of the class with other documented classes. The impression I get from that description is that composition relationships should be represented by the collaboration diagram as well, but it always seems to just be identical to the inheritance one. Is there something I can do to hint to Doxygen the things I would like to appear in this diagram? Does it just not work with PHP?

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  • what is the wrong in this code(openAl in vc++)

    - by maiajam
    hi how are you all? i need your help i have this code #include <conio.h> #include <stdlib.h> #include <stdio.h> #include <al.h> #include <alc.h> #include <alut.h> #pragma comment(lib, "openal32.lib") #pragma comment(lib, "alut.lib") /* * These are OpenAL "names" (or "objects"). They store and id of a buffer * or a source object. Generally you would expect to see the implementation * use values that scale up from '1', but don't count on it. The spec does * not make this mandatory (as it is OpenGL). The id's can easily be memory * pointers as well. It will depend on the implementation. */ // Buffers to hold sound data. ALuint Buffer; // Sources are points of emitting sound. ALuint Source; /* * These are 3D cartesian vector coordinates. A structure or class would be * a more flexible of handling these, but for the sake of simplicity we will * just leave it as is. */ // Position of the source sound. ALfloat SourcePos[] = { 0.0, 0.0, 0.0 }; // Velocity of the source sound. ALfloat SourceVel[] = { 0.0, 0.0, 0.0 }; // Position of the Listener. ALfloat ListenerPos[] = { 0.0, 0.0, 0.0 }; // Velocity of the Listener. ALfloat ListenerVel[] = { 0.0, 0.0, 0.0 }; // Orientation of the Listener. (first 3 elements are "at", second 3 are "up") // Also note that these should be units of '1'. ALfloat ListenerOri[] = { 0.0, 0.0, -1.0, 0.0, 1.0, 0.0 }; /* * ALboolean LoadALData() * * This function will load our sample data from the disk using the Alut * utility and send the data into OpenAL as a buffer. A source is then * also created to play that buffer. */ ALboolean LoadALData() { // Variables to load into. ALenum format; ALsizei size; ALvoid* data; ALsizei freq; ALboolean loop; // Load wav data into a buffer. alGenBuffers(1, &Buffer); if(alGetError() != AL_NO_ERROR) return AL_FALSE; alutLoadWAVFile((ALbyte *)"C:\Users\Toshiba\Desktop\Graduation Project\OpenAL\open AL test\wavdata\FancyPants.wav", &format, &data, &size, &freq, &loop); alBufferData(Buffer, format, data, size, freq); alutUnloadWAV(format, data, size, freq); // Bind the buffer with the source. alGenSources(1, &Source); if(alGetError() != AL_NO_ERROR) return AL_FALSE; alSourcei (Source, AL_BUFFER, Buffer ); alSourcef (Source, AL_PITCH, 1.0 ); alSourcef (Source, AL_GAIN, 1.0 ); alSourcefv(Source, AL_POSITION, SourcePos); alSourcefv(Source, AL_VELOCITY, SourceVel); alSourcei (Source, AL_LOOPING, loop ); // Do another error check and return. if(alGetError() == AL_NO_ERROR) return AL_TRUE; return AL_FALSE; } /* * void SetListenerValues() * * We already defined certain values for the Listener, but we need * to tell OpenAL to use that data. This function does just that. */ void SetListenerValues() { alListenerfv(AL_POSITION, ListenerPos); alListenerfv(AL_VELOCITY, ListenerVel); alListenerfv(AL_ORIENTATION, ListenerOri); } /* * void KillALData() * * We have allocated memory for our buffers and sources which needs * to be returned to the system. This function frees that memory. */ void KillALData() { alDeleteBuffers(1, &Buffer); alDeleteSources(1, &Source); alutExit(); } int main(int argc, char *argv[]) { printf("MindCode's OpenAL Lesson 1: Single Static Source\n\n"); printf("Controls:\n"); printf("p) Play\n"); printf("s) Stop\n"); printf("h) Hold (pause)\n"); printf("q) Quit\n\n"); // Initialize OpenAL and clear the error bit. alutInit(NULL, 0); alGetError(); // Load the wav data. if(LoadALData() == AL_FALSE) { printf("Error loading data."); return 0; } SetListenerValues(); // Setup an exit procedure. atexit(KillALData); // Loop. ALubyte c = ' '; while(c != 'q') { c = getche(); switch(c) { // Pressing 'p' will begin playing the sample. case 'p': alSourcePlay(Source); break; // Pressing 's' will stop the sample from playing. case 's': alSourceStop(Source); break; // Pressing 'h' will pause the sample. case 'h': alSourcePause(Source); break; }; } return 0; } and it is run willbut i cant here any thing also i am new in programong and wont to program a virtual reality sound in my graduation project and start to learn opeal and vc++ but i dont how to start and from where i must begin and i want to ask if i need to learn about API win ?? and if i need how i can learn that thank you alote and i am sorry coz of my english

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  • Browser application & local file system access

    - by Beyond HTML
    I want to enhance my browser-based web application with functionality that enables management of local files and folders. E.g. folder tree structures should be synchronized between local workstation and server via HTTP(S). I am aware of security-related limitations in browser-based applications. However, there are some techniques that "work around" these issues: Signed Java applets (full trust) .NET Windows Forms browser controls (no joke, that works. Just the configuration is horrible) ActiveX My question is: What do you use/suggest, both technology and implementation practice? Key requirement is that the installation process is as simple as possible. Thanks for your opinions!

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  • Why AutoResetEvent and ManualResetEvent does not support name in the constructor?

    - by Ikaso
    On .NET Framework 2.0 AutoResetEvent and ManualResetEvent inherit from EventWaitHandle. The EventWaitHandle class has 4 different constructors. 3 of the constructors support giving a name to the event. On the other hand both ManualResetEvent and AutoResetEvent do not support naming and provide a single constructor that receives the initialState. I can simply inherit from EventWaitHandle and write my own implementation of those classes that support all the constructor overloads, but I don't like to re-invent the wheel if I do not have to. My questions are: Is there a special problem in naming events? Do you have any idea why Microsoft did not support it? Do you have a proposal better than inheriting from the EventWaitHandle class and calling the appropriate constructor as in the following example? public class MyAutoResetEvent: EventWaitHandle { public MyAutoResetEvent(bool initialState) : base(initialState, EventResetMode.AutoReset) { } public MyAutoResetEvent(bool initialState, string name) : base(initialState, EventResetMode.AutoReset, name) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew) : base(initialState, EventResetMode.AutoReset, name, out createdNew) { } public MyAutoResetEvent(bool initialState, string name, out bool createdNew, EventWaitHandleSecurity eventSecurity) : base(initialState, EventResetMode.AutoReset, string.Empty, out createdNew, eventSecurity) { } }

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  • Implementing operator< in C++

    - by Vulcan Eager
    I have a class with a few numeric fields such as: class Class1 { int a; int b; int c; public: // constructor and so on... bool operator<(const Class1& other) const; }; I need to use objects of this class as a key in an std::map. I therefore implement operator<. What is the simplest implementation of operator< to use here?

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  • How to implement file transfer with Java sockets?

    - by ZeKoU
    Hello, I am working on a chat implementation with Java sockets. I have focused on few functionalities, like authentication, one person chat and a group chat. I was thinking about adding file transfer functionality, and I wonder what's the good practice about this. Should I have separate socket on the server with different port listening just for file transfers? Right now input and output streams that I get from server socket are binded to Scanner and PrintWriter objects respectively, so I find it hard to use that for file transfer. Any patterns you guys could recommend or give me good recommendations are very appreciated. Thanks, ZeKoU

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  • drawImage in Java applet flickers in Safari

    - by lcvinny
    I'm having a flicker problem in a Java applet in Safari (Mac). However, it's not the usual double buffering problem. I have isolated it down to one single drawImage call (no redundant repaint, no clear is called), which gives a white flicker before painting the image but not on every repaint. In fact, I measured the duration of the drawImage call, which is normally about 1ms, but up to 30ms about every 5th time paint is called, which is when it flickers. Repaints are triggered when I drag a component or when the window is scrolled. Is this a bug in the java implementation on OSX, and is there a fix for it?

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  • Standard Workflow when working with JPA

    - by jschoen
    I am currently trying to wrap my head around working with JPA. I can't help but feel like I am missing something or doing it the wrong way. It just seems forced so far. What I think I know so far is that their are couple of ways to work with JPA and tools to support this. You can do everything in Java using annotations, and let JPA (whatever implementation you decide to use) create your schema and update it when changes are made. You can use a tool to reverse engineer you database and generate the entity classes for you. When the schema is updated you have to regenerate these classes, or manually update them. There seems to be drawbacks to both, and benefits to both (as with all things). My question is in an ideal situation what is the standard workflow with JPA? Most schemas will require updates during the maintenance phase and especially during the development phase, so how is this handled?

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  • How to give a timeout to an FTP connection

    - by dierre
    The story behind: Old script written in ruby 1.8.6 that opens a connection to a ftp and download a configuration file. For a specific client with a windows ftp server the script just hangs. The log stops writing after it opens the connection to the ftp. It's an old script, it's in ruby and I'm not an expert on it. What I tried: So I tried this implementation of a timeout to check if an ftp connection hangs out with this code Timeout::timeout(5) { ftp = Net::FTP.new(host,pass,host) } The problem is that this isn't working. My guess is that the interpreter stops on opening the connection and the timeout doesn't kill the connection because the interpreter is stuck. Is it possible that that's the problem? Could you tell me if there is maybe an alternative solution or if I'm doing something wrong?

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  • How to know if a detached JPA entity has already been persisted or not ?

    - by snowflake
    I have a JPA entity instance in the web UI layer of my application. I'd like to know at anytime if this entity has been already persisted in database or if it is only present in the user session. It would be in the business layer, I would use entitymanager.contains(Entity) method, but in my UI layer I think I need an extra attribute indicating whether the entity has been saved or not. How implement that ? I'm considering following option for the moment: - a JPA attribute with a default value set by the database, but would force a new read after each update ? - a non JPA attribute manually set in my code or automatically set by JPA? Any advice / other suggestions ? I'm using JPA 1 with Hibernate 3.2 implementation and would prefer stick to the standard.

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  • Why do C++ streams use char instead of unsigned char?

    - by Johannes Schaub - litb
    I've always wondered why the C++ Standard library has instantiated basic_[io]stream and all its variants using the char type instead of the unsigned char type. char means (depending on whether it is signed or not) you can have overflow and underflow for operations like get(), which will lead to implementation-defined value of the variables involved. Another example is when you want to output a byte, unformatted, to an ostream using its put function. Any ideas? Note: I'm still not really convinced. So if you know the definitive answer, you can still post it indeed.

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  • Choosing the non-empty Monoid

    - by Nikita Volkov
    I need a function which will choose a non-empty monoid. For a list this will mean the following behaviour: > [1] `mor` [] [1] > [1] `mor` [2] [1] > [] `mor` [2] [2] Now, I've actually implemented it but am wondering wether there exists some standard alternative, because it seems to be a kind of a common case. Unfortunately Hoogle doesn't help. Here's my implementation: mor :: (Eq a, Monoid a) => a -> a -> a mor a b = if a /= mempty then a else b

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