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  • What about parallelism across network using multiple PCs?

    - by MainMa
    Parallel computing is used more and more, and new framework features and shortcuts make it easier to use (for example Parallel extensions which are directly available in .NET 4). Now what about the parallelism across network? I mean, an abstraction of everything related to communications, creation of processes on remote machines, etc. Something like, in C#: NetworkParallel.ForEach(myEnumerable, () => { // Computing and/or access to web ressource or local network database here }); I understand that it is very different from the multi-core parallelism. The two most obvious differences would probably be: The fact that such parallel task will be limited to computing, without being able for example to use files stored locally (but why not a database?), or even to use local variables, because it would be rather two distinct applications than two threads of the same application, The very specific implementation, requiring not just a separate thread (which is quite easy), but spanning a process on different machines, then communicating with them over local network. Despite those differences, such parallelism is quite possible, even without speaking about distributed architecture. Do you think it will be implemented in a few years? Do you agree that it enables developers to easily develop extremely powerfull stuff with much less pain? Example: Think about a business application which extracts data from the database, transforms it, and displays statistics. Let's say this application takes ten seconds to load data, twenty seconds to transform data and ten seconds to build charts on a single machine in a company, using all the CPU, whereas ten other machines are used at 5% of CPU most of the time. In a such case, every action may be done in parallel, resulting in probably six to ten seconds for overall process instead of forty.

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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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  • How to implement a list fold in Java

    - by Peter Kofler
    I have a List and want to reduce it to a single value (functional programing term "fold", Ruby term "inject"), like Arrays.asList("a", "b", "c") ... fold ... "a,b,c" As I am infected with functional programing ideas (Scala), I am looking for an easier/shorter way to code it than sb = new StringBuilder for ... { append ... } sb.toString

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  • Passing a hostname of over 255 characters to getaddrinfo causes a getaddrinfo failed: memory allocat

    - by darrickc
    I am currently upgrading our software to support ipv6 and in the meantime I'm expanding hostname/ip fields to the max hostname size. In sun documentation it seems like this can be up to 1025 (netdb.h:#define NI_MAXHOST 1025 - this is the recommended hostname allocation define), but when I pass a hostname of over 255 to getaddrinfo I get "getaddrinfo failed: memory allocation failure". I am testing on a Sol10 box. Ideas?

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  • Why I can't called my doSomething method?

    - by Tattat
    This is my DrawSomethingCmd: #import "Command.h"; @interface DrawSomethingCmd : Command { } -(void)doSomething; -(void)execute; @end and the DrawSomethingCmd.m's doSomething method is like that: -(void)doSomething{ NSLog(@"did"); } The Command.h: #import <Foundation/Foundation.h> @interface Command : NSObject { } -(void)execute; And the Command.m: #import "Command.h" @implementation Command -(id)init{ return self; } -(void)execute{ } @end And I have the method like this: DrawSomethingCmd *tempCmd = [[DrawSomethingCmd alloc] init]; [tempCmd doSomething]; But my Console did't show any things on that, what's going on?

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  • inode_operations , warning: initialization from incompatible pointer type

    - by djTeller
    Hi everyone, I'm trying to compile a simple Kernel program that read and write from a proc file. I'm trying to set permission to that file by overriding the permission fp in inode_operations struct (.permission) static int module_permission(struct inode *inode, int op, struct nameidata *foo) { . . . } static struct inode_operations Inode_Ops_4_Our_Proc_File = { .permission = module_permission, /* check for permissions */ }; Our_Proc_File->proc_iops = &Inode_Ops_4_Our_Proc_File; For some reason, when I compile this i get - warning: initialization from incompatible pointer type on the following line: .permission = module_permission, /* check for permissions */ Any idea how to solve this? Thanks!

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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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  • Listening UDP or switch to TCP in a MFC application

    - by Alexander.S
    I'm editing a legacy MFC application, and I have to add some basic network functionalities. The operating side has to receive a simple instruction (numbers 1,2,3,4...) and do something based on that. The clients wants the latency to be as fast as possible, so naturally I decided to use datagrams (UDP). But reading all sorts of resources left me bugged. I cannot listen to UDP sockets (CAsyncSocket) in MFC, it's only possible to call Receive which blocks and waits. Blocking the UI isn't really a smart. So I guess I could use some threading technique, but since I'm not all that experienced with MFC how should that be implemented? The other part of the question is should I do this, or revert to TCP, considering reliability and implementation issues. I know that UDP is unreliable, but just how unreliable is it really? I read that it is up to 50% faster, which is a lot for me. References I used: http://msdn.microsoft.com/en-us/library/09dd1ycd(v=vs.80).aspx

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  • Regarding Shell variable

    - by arav
    I need to call another shell script testarg.sh within my main script. This script testarg.sh has arguments ARG1 ,ARG2, ARG3. I need to call up the below way ./testarg.sh -ARG1 -ARG2 -ARG3 ARG1 and ARG3 argument Variables are mandatory ones. If its not passed to the main script then i quit. ARG2 is an optional one. If the ARG2 variable is not set with value or it's not defined then i need not pass it from main script.So i need to call up the below way ./testarg.sh -ARG1 -ARG3 If the value exist for the ARG2 Varibale then i need to call the below way ./testarg.sh -ARG1 -ARG2 -ARG3 Do i need to have a if else statement for checking the ARG2 variable is empty or null. Is there any other way to do it.

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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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  • get file path from svn diff file with PHP and C

    - by coderex
    hi i have a file having svn diff i wish to extract the filenames form the diff. How to write the parser for that.. Index: libs/constant.php =================================================================== --- libs/constant.php (revision 1243) +++ libs/constant.php (revision 1244) @@ -26,5 +26,5 @@ // changesss - +// test 2 ?> \ No newline at end of file Index: libs/Tools.php =================================================================== --- libs/Tools.php (revision 1243) +++ libs/Tools.php (revision 1244) @@ -34,5 +34,5 @@ // another file an change - +// test ?> \ No newline at end of file Sample output. libs/constant.php libs/Tools.php How to write parser in PHP and C.

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  • From a programmer's perspective, which is your everyday Python uses?

    - by Vimvq1987
    I've finished my thesis and now having a free time. I intend to learn another language, and Python seems to be a good choice. I'll probably have to use .NET for every day works, but I heard that Python helps programmer a lot, in mean of automation. That would be great if I can write "small" Python scripts to do something automatically. From a programmer's perspective, which is your everyday Python's uses? What did it do to have your works done?

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  • PHP string to object name.

    - by Smickie
    Ok I have a string... $a_string = "Product"; and I want to use this string in a call to a object like this: $this->$a_string->some_function(); How the dickens do I dynamically call that object? (don't think Im on php 5 mind)

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  • Why are developers proud to say our application is XXX lines of code? [closed]

    - by mbcrump
    I admit, I used to do it. I was proud to tell a fellow developer my application is 10K+ lines of code. I thought it was a "Look at me, I'm smart" statement. Time passed and I realized that a experienced developer would be constantly refactoring all of his code. Not only for the sake of remembering what it was doing, but because he realizes he is smarter today than he was yesterday. No longer was it cool to have multiple nested if statements or completely ignoring generics/lambdas. So, whats your take on this? Do you do it and why?

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  • Abstracting the adding of click events to elements selected by class using jQuery

    - by baroquedub
    I'm slowly getting up to speed with jQuery and am starting to want to abstract my code. I'm running into problems trying to define click events at page load. In the code below, I'm trying to run through each div with the 'block' class and add events to some of its child elements by selecting them by class: <script language="javascript" type="text/javascript"> $(document).ready(function (){ $('HTML').addClass('JS'); // if JS enabled, hide answers $(".block").each(function() { problem = $(this).children('.problem'); button = $(this).children('.showButton'); problem.data('currentState', 'off'); button.click(function() { if ((problem.data('currentState')) == 'off'){ button.children('.btn').html('Hide'); problem.data('currentState', 'on'); problem.fadeIn('slow'); } else if ((problem.data('currentState')) == 'on'){ button.children('.btn').html('Solve'); problem.data('currentState', 'off'); problem.fadeOut('fast'); } return false; }); }); }); </script> <style media="all" type="text/css"> .JS div.problem{display:none;} </style> <div class="block"> <div class="showButton"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem"> <p>Answer 1</p> </div> </div> <div class="block"> <div class="showButton"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem"> <p>Answer 2</p> </div> </div> Unfortunately using this, only the last of the divs' button actually works. The event is not 'localised' (if that's the right word for it?) i.e. the event is only applied to the last $(".block") in the each method. So I have to laboriously add ids for each element and define my click events one by one. Surely there's a better way! Can anyone tell me what I'm doing wrong? And how I can get rid of the need for those IDs (I want this to work on dynamically generated pages where I might not know how many 'blocks' there are...) <script language="javascript" type="text/javascript"> $(document).ready(function (){ $('HTML').addClass('JS'); // if JS enabled, hide answers // Preferred version DOESN'T' WORK // So have to add ids to each element and laboriously set-up each one in turn... $('#problem1').data('currentState', 'off'); $('#showButton1').click(function() { if (($('#problem1').data('currentState')) == 'off'){ $('#showButton1 > a').html('Hide'); $('#problem1').data('currentState', 'on'); $('#problem1').fadeIn('slow'); } else if (($('#problem1').data('currentState')) == 'on'){ $('#showButton1 > a').html('Solve'); $('#problem1').data('currentState', 'off'); $('#problem1').fadeOut('fast'); } return false; }); $('#problem2').data('currentState', 'off'); $('#showButton2').click(function() { if (($('#problem2').data('currentState')) == 'off'){ $('#showButton2 > a').html('Hide'); $('#problem2').data('currentState', 'on'); $('#problem2').fadeIn('slow'); } else if (($('#problem2').data('currentState')) == 'on'){ $('#showButton2 > a').html('Solve'); $('#problem2').data('currentState', 'off'); $('#problem2').fadeOut('fast'); } return false; }); }); </script> <style media="all" type="text/css"> .JS div.problem{display:none;} </style> <div class="block"> <div class="showButton" id="showButton1"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem" id="problem1"> <p>Answer 1</p> </div> </div> <div class="block"> <div class="showButton" id="showButton2"> <a href="#" title="Show solution" class="btn">Solve</a> </div> <div class="problem" id="problem2"> <p>Answer 2</p> </div> </div>

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  • Developing a project which is an implementation of an open standard/protocol

    - by dotnetdev
    Hi, A lot of interesting code/projects are implementations of protocols, eg SNMP. How are projects like these, which depend on implementing a certain format, developed? Is the process something like get the guidelines of the protocol and then implement code which follows it. For example, XML-RPC is about transmitting XML docs between client/server, so the documentation on this protocol must outline the structure of the XML documents and then the way the transportation between client and server works, so the coder will implement this sort of functionality (xml doc construction, networking between the client and server). Projects I am thinking of (not to develop) are C# libraries which can interpret .PSDs, make VHDs, etc. So if I was to develop a C# app to implement .AI files (Illustrator files), what would be the steps I would look at (such as contacting Adobe, etc)? Is this the way such projects are developed?

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  • Writing an auto-memoizer in Scheme. Help with macro and a wrapper.

    - by kunjaan
    I am facing a couple of problems while writing an auto-memoizer in Scheme. I have a working memoizer function, which creats a hash table and checks if the value is already computed. If it has been computed before then it returns the value else it calls the function. (define (memoizer fun) (let ((a-table (make-hash))) (?(n) (define false-if-fail (?() #f)) (let ((return-val (hash-ref a-table n false-if-fail))) (if return-val return-val (begin (hash-set! a-table n (fun n)) (hash-ref a-table n))))))) Now I want to create a memoize-wrapper function like this: (define (memoize-wrapper function) (set! function (memoizer function))) And hopefully create a macro called def-memo which defines the function with the memoize-wrapper. eg. the macro could expand to (memoizer (define function-name arguments body ...) or something like that. So that I should be able to do : (def-memo (factorial n) (cond ((= n 1) 1) (else (* n (factorial (- n 1)))))) which should create a memoized version of the factorial instead of the normal slow one. My problem is that the The memoize-wrapper is not working properly, it doesnt call the memoized function but the original function. I have no idea how to write a define inside of the macro. How do I make sure that I can get variable lenght arguments and variable length body? How do I then define the function and wrap it around with the memoizer? Thanks a lot.

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  • Linux Kernel - Socket file descriptor close location

    - by NTek
    Where in the linux kernel does the closing of a socket's file descriptor occur? I know for a file, the file's file descriptor is closed in fs/open.cs function sys_close(). However, for a socket file descriptor, is this the same location or somewhere else? Also, do sockets utilize the file.c alloc_fd to allocate the file descriptor or do they utilize some other function?

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  • Pros and Cons of Proprietary Software

    - by Jon Purdy
    Proprietary software is about as good as open-source software. There are so many problems with proprietary technologies, however, that I'm beginning to think it's best to avoid them: The software will only be maintained as long as the company exists (and profits). The level of security of the application is as unknowable as the source code. Alterations and derivative works, however necessary and beneficial, are disallowed. I simply don't see any point in even learning to use such systems as those created by Microsoft and Apple. Of course I don't pretend that ignorance is the superior option: one has to have a certain working knowledge simply because of the ubiquity of these things. I just don't see any reason why, as an independent developer, I should ever consider it a remotely good idea to actually use them. So that's the question, or discussion topic, or what have you: In what ways do developers benefit at all from using closed-source development software?

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