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  • C++ networking simple send and receive

    - by Wallter
    I'm trying to link 10 computers together, the program i would like to write would have one 'control' computer. From what I've looked up this computer would take all the packets sent over the network and do a echo with them... right? The other computers would need to be able to send information (then echoed to the others) to the 'control' ... is there a easy! or simple way to do this? From what I've seen i want a non-blocking socket? I have looked into sockets and such but for an armature programmer like me, this seems like a daunting task :) I'm kind-of looking for an easy class implication that has a send() and an event driven recv(). I'm not going to be sending that much information over the network.

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  • Are there any Parsing Expression Grammar (PEG) libraries for Javascript or PHP?

    - by Peter J. Wasilko
    I find myself drawn to the Parsing Expression Grammar formalism for describing domain specific languages, but so far the implementation code I've found has been written in languages like Java and Haskell that aren't web server friendly in the shared hosting environment that my organization has to live with. Does anyone know of any PEG libraries or PackRat Parser Generators for Javascript or PHP? Of course code generators in any languages that can produce Javascript or PHP source code would do the trick.

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  • tutorials/books to create a plugin/module/library?

    - by fayer
    i wonder if there are tutorials/books explaining how you create a library/plugin/module for other to implement? libraries/frameworks like solr, doctrine, codeigniter etc. cause it seems that they follow the same pattern. having one "bootstrap" file to load configurations, other classes and so on. i aim to understand the basics, so i can create a such library. cause at the moment i want to code an address book that other can use. just include a bootstrap file and they are ready to use my classes (like Doctrine). recommendations of sources to learn these things of stuff? you experienced guys, how did you learn it? thanks.

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  • Best Functional Approach

    - by dbyrne
    I have some mutable scala code that I am trying to rewrite in a more functional style. It is a fairly intricate piece of code, so I am trying to refactor it in pieces. My first thought was this: def iterate(count:Int,d:MyComplexType) = { //Generate next value n //Process n causing some side effects return iterate(count - 1, n) } This didn't seem functional at all to me, since I still have side effects mixed throughout my code. My second thought was this: def generateStream(d:MyComplexType):Stream[MyComplexType] = { //Generate next value n return Stream.cons(n, generateStream(n)) } for (n <- generateStream(initialValue).take(2000000)) { //process n causing some side effects } This seemed like a better solution to me, because at least I've isolated my functional value-generation code from the mutable value-processing code. However, this is much less memory efficient because I am generating a large list that I don't really need to store. This leaves me with 3 choices: Write a tail-recursive function, bite the bullet and refactor the value-processing code Use a lazy list. This is not a memory sensitive app (although it is performance sensitive) Come up with a new approach. I guess what I really want is a lazily evaluated sequence where I can discard the values after I've processed them. Any suggestions?

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  • Virtual audio driver (microphone)

    - by Dalamber
    Hello guys, I want to develop a virtual microphone driver. Please, do not say anything about DirectShow - that's not "the way". I need a solution that will work with any software including Skype and MSN. And DirectShow doesn't fit these requirements. I found AVStream Filter-Centric Simulated Capture Driver (avssamp.sys) in Windows 7 WDK. What I need is an audio part of it. By default it reads avssamp.wav and plays it. But this driver is registered as WDM streaming capture device. And I want it in Audio Capture Device. There are some posts in the web but they are all the same: http://www.tech-archive.net/Archive/Development/microsoft.public.development.device.drivers/2005-05/msg00124.html http://www.winvistatips.com/problem-installing-avssamp-audio-capture-sources-category-t184898.html I think registering this filter-driver as audio capture device will make Skype recognize it as a microphone and thefore I will be able to push any PCM file as if it goes from mic. If someone already faced this problem before, please help. Thanks in advance.

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  • Daemonize() issues on Debian

    - by djTeller
    Hi, I'm currently writing a multi-process client and a multi-treaded server for some project i have. The server is a Daemon. In order to accomplish that, i'm using the following daemonize() code: static void daemonize(void) { pid_t pid, sid; /* already a daemon */ if ( getppid() == 1 ) return; /* Fork off the parent process */ pid = fork(); if (pid < 0) { exit(EXIT_FAILURE); } /* If we got a good PID, then we can exit the parent process. */ if (pid > 0) { exit(EXIT_SUCCESS); } /* At this point we are executing as the child process */ /* Change the file mode mask */ umask(0); /* Create a new SID for the child process */ sid = setsid(); if (sid < 0) { exit(EXIT_FAILURE); } /* Change the current working directory. This prevents the current directory from being locked; hence not being able to remove it. */ if ((chdir("/")) < 0) { exit(EXIT_FAILURE); } /* Redirect standard files to /dev/null */ freopen( "/dev/null", "r", stdin); freopen( "/dev/null", "w", stdout); freopen( "/dev/null", "w", stderr); } int main( int argc, char *argv[] ) { daemonize(); /* Now we are a daemon -- do the work for which we were paid */ return 0; } I have a strange side effect when testing the server on Debian (Ubuntu). The accept() function always fail to accept connections, the pid returned is -1 I have no idea what causing this, since in RedHat & CentOS it works well. When i remove the call to daemonize(), everything works well on Debian, when i add it back, same accept() error reproduce. I've been monitring the /proc//fd, everything looks good. Something in the daemonize() and the Debian release just doesn't seem to work. (Debian GNU/Linux 5.0, Linux 2.6.26-2-286 #1 SMP) Any idea what causing this? Thank you

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  • Avoiding explicit recursion in Haskell

    - by Travis Brown
    The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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  • Why is glpk-java.jar not the same across all platforms?

    - by pruefsumme
    I'm using glpk-java in one of my projects. It provides a JNI to GLPK, a free LP/MIP solver. To use it under different platforms, you need different shared libraries (libglpk.so under Linux, libglpk.dylib under Mac OS X, glpk.dll under Windows) which is fully understandable. In addition, a java library is needed: glpk-java.jar. It's created as part of the build process. I was wondering why this JAR file (which only contains .class files) is different under different platforms? I.e., I cannot use the same glpk-java.jar under Linux and Mac OS X which means that I cannot put this file under revision control.

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  • F# replace ref variable with something fun

    - by Stephen Swensen
    I have the following F# functions which makes use of a ref variable to seed and keep track of a running total, something tells me this isn't in the spirit of fp or even particular clear on its own. I'd like some direction on the clearest (possible fp, but if an imperative approach is clearer I'd be open to that) way to express this in F#. Note that selectItem implements a random weighted selection algorithm. type WeightedItem(id: int, weight: int) = member self.id = id member self.weight = weight let selectItem (items: WeightedItem list) (rand:System.Random) = let totalWeight = List.sumBy (fun (item: WeightedItem) -> item.weight) items let selection = rand.Next(totalWeight) + 1 let runningWeight = ref 0 List.find (fun (item: WeightedItem) -> runningWeight := !runningWeight + item.weight !runningWeight >= selection) items let items = [new WeightedItem(1,100); new WeightedItem(2,50); new WeightedItem(3,25)] let selection = selectItem items (new System.Random())

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  • How to pass a class method as an argument for another function in C++ and openGL?

    - by tsubasa
    I know this thing works: void myDisplay() { ... } int main() { ... glutDisplayFunc(myDisplay) ... } so I tried to include myDisplay() function to a class that I made. Because I want to overload it in the future with a different class. However, the compiler complains that argument of type 'void (ClassBlah::)()' does not match 'void(*)()' . Here is the what I try to make: class ClassBlah { .... void myDisplay() .... } ...... int main() { ... ClassBlah blah glutDisplayFunc(blah.myDisplay) ... } Does anybody knows how to fix this problem? Many thanks.

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  • Not able to kill bad kernel running on NVIDIA GPU

    - by arvindkgs
    Hi, I am in a real fix. Please help. Its urgent. I have a host process that spawns multiple host(CPU) threads. These threads in turn call the CUDA kernel. These CUDA kernels are written by external users. So it might be bad kernels that enter infinite loop. In order to overcome this I have put a time-out of 2 mins that will kill the corresponding CPU thread. Will killing the CPU thread also kill the kernel running on the GPU? As far as what I have tested it does'nt. How can I also kill all the threads currently running in the GPU? Thanks, Arvind

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  • Howw to add new value with generic Repository if there are foreign keys (EF-4)?

    - by Phsika
    i try to write a kind of generic repository to add method. Everything is ok to add but I have table which is related with two tables with FOREIGN KEY.But Not working because of foreign key public class DomainRepository<TModel> : IDomainRepository<TModel> where TModel : class { #region IDomainRepository<T> Members private ObjectContext _context; private IObjectSet<TModel> _objectSet; public DomainRepository() { } public DomainRepository(ObjectContext context) { _context = context; _objectSet = _context.CreateObjectSet<TModel>(); } //do something..... public TModel Add<TModel>(TModel entity) where TModel : IEntityWithKey { EntityKey key; object originalItem; key = _context.CreateEntityKey(entity.GetType().Name, entity); _context.AddObject(key.EntitySetName, entity); _context.SaveChanges(); return entity; } //do something..... } Calling REPOSITORY: //insert-update-delete public partial class AddtoTables { public table3 Add(int TaskId, int RefAircraftsId) { using (DomainRepository<table3> repTask = new DomainRepository<table3>(new TaskEntities())) { return repTask.Add<table3>(new table3() { TaskId = TaskId, TaskRefAircraftsID = RefAircraftsId }); } } } How to add a new value if this table includes foreign key relation

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  • How do you tell if a string contains another string in Unix shell scripting?

    - by Matt
    Hi all, I want to write a Unix shell script that will do various logic if there is a string inside of another string. For example, if I am in a certain folder, branch off. Could someone please tell me how to accomplish this? If possible I would like to make this not shell specific (i.e. not bash only) but if there's no other way I can make do with that. #!/bin/sh CURRENT_DIR=`pwd` if [ CURRENT_DIR contains "String1" ] then echo "String1 present" elif [ CURRENT_DIR contains "String1" ] then echo "String2 present" else echo "Else" fi

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  • Multiple-File Template Implementation

    - by Maxpm
    With normal functions, the declaration and definition are often separated across multiple files like so: // Foo.h namespace Foo { void Bar(); } . // Foo.cpp #include "Foo.h" void Foo::Bar() { cout << "Inside function." << endl; } It is my understanding that this cannot be done with templates. The declaration and definition must not be separate because the appropriate form of the template is created "on-demand" when needed. So, how and where are templates typically defined in a multiple-file project like this? My intuition is that it would be in Foo.cpp because that's where the "meat" of functions normally is, but on the other hand it's the header file that's going to be included.

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  • [PHP] Dynamic cron jobs?

    - by Frankie Laguna
    I'm writing a script that needs to be called at a random time during the day, but am not sure how to accomplish this. I don't want to waste server resources to run a cron job every minute. I want the script to be called at random, so generating the random times for say a month in advance and then creating cron jobs for each of them isn't what I'm looking for. Also this script only needs to be executed once a day. Thanks in advance!

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  • socket problem in java

    - by stefan89
    I have two classes X and Y, like this: class X implements Serializable { int val1; Y val2; } class Y implements Serializable { int val; } I want to transmit an object of type X from a client to server but i can't because the class X has a field of type Y. I replace the field of type Y with a field of type X in class X and it works.

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