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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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  • Optimising (My)SQL Query

    - by Simon
    I usually use ORM instead of SQL and I am slightly out of touch on the different JOINs... SELECT `order_invoice`.*, `client`.*, `order_product`.*, SUM(product.cost) as net FROM `order_invoice` LEFT JOIN `client` ON order_invoice.client_id = client.client_id LEFT JOIN `order_product` ON order_invoice.invoice_id = order_product.invoice_id LEFT JOIN `product` ON order_product.product_id = product.product_id WHERE (order_invoice.date_created >= '2009-01-01') AND (order_invoice.date_created <= '2009-02-01') GROUP BY `order_invoice`.`invoice_id` The tables/ columns are logically names... it's an shop type application... the query works... it's just very very slow... I use the Zend Framework and would usually use Zend_Db_Table_Row::find(Parent|Dependent)Row(set)('TableClass') but I have to make lots of joins and I thought it'll improve performance by doing it all in one query instead of hundreds... Can I improve the above query by using more appropriate JOINs or a different implementation? Many thanks.

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  • Core Data and BOOL setup

    - by John Valen
    I am working on an app that uses Core Data as its backend for managing SQLite records. I have everything working with strings and numbers, but have just tried adding BOOL fields and can't seem to get things to work. In the .xcdatamodel, I have added a field to my object called isCurrentlyForSale which is not Optional, not Transient, and not Indexed. The attribute's type is set to Boolean with default value NO. When I created the class files from the data model, the boilerplate code added for this property in the .h header was: @property (nonatomic, retain) NSNumber * isCurrentlyForSale; along with the @dynamic isCurrentlyForSale; in the .m implementation file. I've always worked with booleans as simple BOOLs. I've read that I could use NSNumber's numberWithBool and boolValue methods, but this seems like an aweful lot of extra code for something so simple. Can the @property in the header be changed to a simple BOOL? If so is there anything to watch out for? Thanks -John

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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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  • 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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  • 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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  • 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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  • 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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  • Using Linq to select a range of members in a list

    - by clintp
    Given a list of elements like so: int[] ia = new int[] { -4, 10, 11, 12, 13, -1, 9, 8, 7, 6, 5, 4, -2, 6, 15, 32, -5, 6, 19, 22 }; Is there an easy way in Linq to do something along the lines of "Select the elements from the -1 up to the next negative number (or the list exhausts)"? A successful result for -1 would be (-1, 9, 8, 7, 6, 5, 4). Using -2 would give the result (-2, 6, 15, 32). Not a homework problem. I'm just looking at an implementation using a bool, a for loop, and an if wondering if there's a cleaner way to do it.

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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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  • Basic Client-Server Design for persistent connections?

    - by cam
    Here's as far as I understand it: Client & Server make connection Client sends server data Server interprets data, sends client data So on, and so forth, until client sends disconnect signal. I'm just wondering about implementation. Step 2 and 3 are confusing to me, maybe I'm over-complicating it. Is there anymore to interpreting the data than a giant switch statement? Any good books on client/server design? Specifically talking about multithreaded servers, scalability, and message design (byte 1 = header info, byte 2 = blah blah, etc)? Specifically geared towards C++.

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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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  • 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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  • 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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  • Optional structural typing possibilty in C++ or anyother language?

    - by ambhai
    In C++ how to tell compiler that Ogre::Vector3 IS_SAME_AS SomeOtherLIB::Vector3 ? I feel that.. in languages like c++ which are not structural typed but there are cases when it makes sense. Normally as game developer when working with 4+ libraries that provide sort or their own Vector3 implementation. The code is littered with ToOgre, ToThis, ToThat conversion function. Thats a lot of Float3 copying around which should not happen on first place. Is in C++ or any other languages where we dont have to convert (copying) from one type to another which is essentially the samething. But any solution in C++ as most of the good gamedevs libs are for c/c++.

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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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  • J2ME's extra annoying HTTP permission prompt

    - by Hans Malherbe
    Some phones only prompt the user for permission the first time a connection is made. Others pop up the permission prompt whenever the MIDlet attempts to make a HTTP connection! What are the options if we want to suppress the prompt? Can we sign the JAR using only one CA (Certificate Authority) and have it work on all devices? Do we have to pay for a signature on every release? Is it an option to create our own CA certificate and tell our customers to install it on there device? Alternatively, it seems that plain socket connections do not suffer so. Is there a free implementation of HTTP on top of TCP for J2ME?

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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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  • 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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  • Heavy use of templates for mobile platforms

    - by Chris P. Bacon
    I've been flicking through the book Modern C++ Design by Andrei Alexandrescu and it seems interesting stuff. However it makes very extensive use of templates and I would like to find out if this should be avoided if using C++ for mobile platform development (Brew MP, WebOS, iOS etc.) due to size considerations. In Symbian OS C++ the standard use of templates is discouraged, the Symbian OS itself uses them but using an idiom known as thin templates where the underlying implementation is done in a C style using void* pointers with a thin template layered on top of this to achieve type safety. The reason they use this idiom as opposed to regular use of templates is specifically to avoid code bloating. So what are opinions (or facts) on the use of templates when developing applications for mobile platforms.

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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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  • 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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  • 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 do you write an idiomatic Scala Quicksort function?

    - by Don Mackenzie
    I recently answered a question with an attempt at writing a quicksort function in scala, I'd seen something like the code below written somewhere. def qsort(l: List[Int]): List[Int] = { l match { case Nil => Nil case pivot::tail => qsort(tail.filter(_ < pivot)) ::: pivot :: qsort(tail.filter(_ >= pivot)) } } My answer received some constructive criticism pointing out that List was a poor choice of collection for quicksort and secondly that the above wasn't tail recursive. I tried to re-write the above in a tail recursive manner but didn't have much luck. Is it possible to write a tail recursive quicksort? or, if not, how can it be done in a functional style? Also what can be done to maximise the efficiency of the implementation? Thanks in advance.

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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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