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  • C++ Program Flow: Sockets in an Object and the Main Function

    - by jfm429
    I have a rather tricky problem regarding C++ program flow using sockets. Basically what I have is this: a simple command-line socket server program that listens on a socket and accepts one connection at a time. When that connection is lost it opens up for further connections. That socket communication system is contained in a class. The class is fully capable of receiving the connections and mirroring the data received to the client. However, the class uses UNIX sockets, which are not object-oriented. My problem is that in my main() function, I have one line - the one that creates an instance of that object. The object then initializes and waits. But as soon as a connection is gained, the object's initialization function returns, and when that happens, the program quits. How do I somehow wait until this object is deleted before the program quits? Summary: main() creates instance of object Object listens Connection received Object's initialization function returns main() exits (!) What I want is for main() to somehow delay until that object is finished with what it's doing (aka it will delete itself) before it quits. Any thoughts?

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  • Why does Java force user-agent through simple Socket IO?

    - by Zombies
    I am using nothing but raw Socket IO. There isn't one HttpURLConnection nor any http client libs in my project. When I run it through wireshark I see somethign very revealing: GET / HTTP/1.1 User-Agent: Java/1.6.0_15 Host: www.google.com Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2 Connection: keep-alive Here is the crazy part, I never put ANY of that in my original request. My original request was: "GET http://www.google.com/ HTTP/1.1\r\n" + "Host: www.google.com\r\n" + "User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.8) Gecko/20100214 Ubuntu/9.10 (karmic) Firefox/3.5.8\r\n" + "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n" + "Accept-Language: en-us,en;q=0.5\r\n" + "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n" + "Keep-Alive: 300\r\n" + "\r\n"; I am using the default Sun JVM.

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  • Algorithm to distribute objects in a box (like InDesign, Illustrator, Draw!)

    - by Rafael Almeida
    I have a set of rectangles with their corresponding positions and a big rectangle which serves as the 'bounding box' for these rectangles. I would like to know of an algorithm that would 'distribute the free space' evenly among the rectangles. Some of you may be familiar with the Distribute Spacing option in Adobe InDesign and similar layout-oriented apps. That would be what I'm looking for. I did try looking it up, but I'm not familiar with 'graphical' algorithms terminology and trying only terms relating to 'distribute' mainly yields results about Distributed Computing. So, even the names of the algorithms or better terms to look up would be a big help. Finally, the algorithm doesn't need to be rigorously the same as InDesign's one: pretty much any algorithm that 'distributes' objects inside a region will work fine. In fact, since I'm striving for visual appeal mainly, the more suggestions the better. =D

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  • IE to show Full URL path in the Title bar as in Status Bar

    - by Slavin
    Windows XP and IE8. Tabbed Browsing is OFF. So every single web page has its own title. I want to see in the title the same as I see in the Status bar i.e. I want the full URL of the web page I am viewing to be displayed in the Title bar, and so in the Task bar button too. How to achieve this? Thanks for all the answers in advance. Looks like this is rare case.

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  • Is it possible to create a domain model for legacy code without refactoring?

    - by plaureano
    I currently have a client that wants me to 'abstract' out a domain model from the existing code but they specifically said that I shouldn't refactor the existing code itself. My question is 1) whether or not this is advisable and 2) what techniques would you apply in this scenario if you can't refactor the code yet they expect you to come up with a model for it? (EDIT: I can't quite put my finger on it, but somehow, not being able to refactor in this case just feels wrong. Has anyone else run into this type of scenario?)

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  • Sparse linear program solver

    - by Jacob
    This great SO answer points to a good sparse solver, but I've got constraints on x (for Ax = b) such that each element in x is >=0 an <=N. The first thing which comes to mind is an LP solver for large sparse matrices. Any ideas/recommendations?

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  • How can I pass methods in javascript?

    - by peterjwest
    I often need to pass methods from objects into other objects. However I usually want the method to be attached to the original object (by attached I mean 'this' should refer to the original object). I know a few ways to do this: a) In the object constructor: ObjectA = function() { var that = this; var method = function(a,b,c) { that.abc = a+b+c }} b) In objectA which has been passed objectB: objectB.assign(function(a,b,c) { that.method(a,b,c) }) c) Outside both objects: objectB.assign(function(a,b,c) { objectA.method(a,b,c) }) I want to know if there is a simpler way to pass methods attached to their original objects.

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  • Support Open Source Projects via T-Shirts

    - by The MYYN
    Can we get a list of free and open source projects, which can be supported through purchasing branded garment? Free Software Foundation http://shop.fsf.org/ OpenBSD https://https.openbsd.org/cgi-bin/order Mozilla http://store.mozilla.org/ ps. I know this is extremly off-topic. But I'd like to buy clothing and support open source at the same time. And I'd like to know, where this is possible.

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  • Prolog: using the sort/2 predicate

    - by Øyvind Hauge
    So I'm trying to get rid of the wrapper clause by using the sort library predicate directly inside split. What split does is just generating a list of numbers from a list that looks like this: [1:2,3:2,4:6] ---split-- [1,2,3,2,4,6]. But the generated list contains duplicates, and I don't want that, so I'm using the wrapper to combine split and sort, which then generates the desired result: [1,2,3,4,6]. I'd really like to get rid of the wrapper and just use sort within split, however I keep getting "ERROR: sort/2: Arguments are not sufficiently instantiated." Any ideas? Thanks :) split([],[]). split([H1:H2|T],[H1,H2|NT]) :- split(T,NT). wrapper(L,Processed) :- split(L,L2), sort(L2,Processed).

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  • Using sys/socket.h functions on windows

    - by BSchlinker
    Hello, I'm attempting to utilize the socket.h functions within Windows. Essentially, I'm currently looking at the sample code at http://beej.us/guide/bgnet/output/html/multipage/clientserver.html#datagram. I understand that socket.h is a Unix function -- is there anyway I can easily emulate that environment while compiling this sample code? Does a different IDE / compiler change anything? Otherwise, I imagine that I need to utilize a virtualized Linux environment, which may be best anyways as the code will most likely be running in a UNIX environment. Thanks.

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  • Haskell - Parsec Parsing <p> element

    - by Martin
    I'm using Text.ParserCombinators.Parsec and Text.XHtml to parse an input like this: This is the first paragraph example\n with two lines\n \n And this is the second paragraph\n And my output should be: <p>This is the first paragraph example\n with two lines\n</p> <p>And this is the second paragraph\n</p> I defined: line= do{ ;t<-manyTill (anyChar) newline ;return t } paragraph = do{ t<-many1 (line) ;return ( p << t ) } But it returns: <p>This is the first paragraph example\n with two lines\n\n And this is the second paragraph\n</p> What is wrong? Any ideas? Thanks!

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  • Keeping sync in multiplayer RTS game that uses floating point arithmetic

    - by Calmarius
    I'm writing a 2D space RTS game in C#. Single player works. Now I want to add some multiplayer functionality. I googled for it and it seems there is only one way to have thousands of units continuously moving without a powerful net connection: send only the commands through the network while running the same simulation at every player. And now there is a problem the entire engine uses doubles everywhere. And floating point calculations are depends heavily on compiler optimalizations and cpu architecture so it is very hard to keep things syncronized. And it is not grid based at all, and have a simple phisics engine to move the space-ships (space ships have impulse and angular-momentum...). So recoding the entire stuff to use fixed point would be quite cumbersome (but probably the only solution). So I have 2 options so far: Say bye to the current code and restart from scratch using integers Make the game LAN only where there is enough bandwidth to have 8 players with thousands of units and sending the positions and orientation etc in (almost) every frame... So I looking for better opinions, (or even tips on migrating the code to fixed-point without messing everything up...)

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  • Sorting data by relevance, from multiple tables

    - by Oden
    Hey, How is it possible to sort data from multiple tables by relevance? My table structure is following: I have 3 tables in my database, one table contains the name of solar systems, the second for e.g. of planets. There is one more table, witch is a connection between solar systems and planets. If I want to get data of a planet, witch is in the Milky Way, i post this data to the server, and it gives me a multi-dimensional array witch contains: The Milky Way, with every planet in it Every planet, witch name contains the string Milky Way (maybe thats a bat example because i don't think that theres but one planet with this name, but the main concept is on file) But, i want to set the most relevant restaurants to the top of the array. (for the relevance i would check the description of the restaurants or something like that) So, how would you do that kind of data sorting?

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  • Why doesn't infinite recursion hit a stack overflow exception in F#?

    - by Amazingant
    I know this is somewhat the reverse of the issue people are having when they ask about a stack overflow issue, but if I create a function and call it as follows, I never receive any errors, and the application simply grinds up a core of my CPU until I force-quit it: let rec recursionTest x = recursionTest x recursionTest 1 Of course I can change this out so it actually does something like this: let rec recursionTest (x: uint64) = recursionTest (x + 1UL) recursionTest 0UL This way I can occasionally put a breakpoint in my code and see the value of x is going up rather quickly, but it still doesn't complain. Does F# not mind infinite recursion?

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  • The behavior of send() and recv() in socket communication

    - by gc
    The following is the setup: Server Client | | accept connect | | v | send msg1- | | | v v recv <- send | | v v send msg2- recv | | v v close Here is my question: 1. Client actually receives msg1 before it closes, why is it like this? 2. send msg2 returns normally. Since client closes after receiving msg1, why is send msg2 successful?

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  • What is the best Linux distribution as a Xen host?

    - by St3fan
    I ordered a server for the home office and I would like to partition it with Xen. I think this will keep things clean and easier to maintain. I will be running things like MySQL, PostgreSQL, Tomcat and my own code on this machine. My question is: what freely available Linux distribution has the best Xen hosting facilities?

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  • Appending an element to a collection using LINQ

    - by SRKX
    I am trying to process some list with a functional approach in C#. The idea is that I have a collection of Tuple<T,double> and I want to change the Item 2 of some element T. The functional way to do so, as data is immutable, is to take the list, filter for all elements where the element is different from the one to change, and the append a new tuple with the new values. My problem is that I do not know how to append the element at the end. I would like to do: public List<Tuple<T,double>> Replace(List<Tuple<T,double>> collection, T term,double value) { return collection.Where(x=>!x.Item1.Equals(term)).Append(Tuple.Create(term,value)); } But there is no Append method. Is there something else?

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  • How to initialize F# list when size is unknown, using while..do loop

    - by James Black
    I have a function that will parse the results of a DataReader, and I don't know how many items are returned, so I want to use a while..do loop to iterate over the reader, and the outcome should be a list of a certain type. (fun(reader) -> [ while reader.Read() do new CityType(Id=(reader.GetInt32 0), Name=(reader.GetString 1), StateName=(reader.GetString 2)) ]) This is what I tried, but the warning I get is: This expression should have type 'unit', but has type 'CityType'. Use 'ignore' to discard the result of the expression, or 'let' to bind the result to a name. So what is the best way to iterate over a DataReader and create a list?

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  • cons operator (::) in F#

    - by Max
    The :: operator in F# always prepends elements to the list. Is there an operator that appends to the list? I'm guessing that using @ operator [1; 2; 3] @ [4] would be less efficient, than appending one element.

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  • socket timeout and remove O_NONBLOCK option

    - by juxstapose
    Hello, I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally. References: C: socket connection timeout How to reset a socket back to blocking mode (after I set it to nonblocking mode)? Code: fd_set fdset; struct timeval tv; fcntl(dsock, F_SETFL, O_NONBLOCK); tv.tv_sec = theDeviceTimeout; tv.tv_usec = 0; int retries=0; logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry); for(retries=0;retries<theDeviceRetry;retries++) { connect(dsock, (struct sockaddr *)&daddr, sizeof daddr); FD_ZERO(&fdset); FD_SET(dsock, &fdset); if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) { int so_error; socklen_t slen = sizeof so_error; getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen); if (so_error == 0) { logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP); break; } else { logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries); logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno)); logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error)); continue; } } } int opts; opts = fcntl(dsock,F_GETFL); logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries); opts ^= O_NONBLOCK; fcntl(dsock, F_SETFL, opts);

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  • Bi-directional communication with 1 socket - how to deal with collisions?

    - by Zwei Steinen
    Hi, I have one app. that consists of "Manager" and "Worker". Currently, the worker always initiates the connection, says something to the manager, and the manager will send the response. Since there is a LOT of communication between the Manager and the Worker, I'm considering to have a socket open between the two and do the communication. I'm also hoping to initiate the interaction from both sides - enabling the manager to say something to the worker whenever it wants. However, I'm a little confused as to how to deal with "collisions". Say, the manager decides to say something to the worker, and at the same time the worker decides to say something to the manager. What will happen? How should such situation be handled? P.S. I plan to use Netty for the actual implementation. Thank you very much in advance!

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  • book with good examples for each implementation?

    - by ajsie
    i've read about design patterns and it seems that there are a lot of different design patterns to use. i wonder if there are some books that acts like a reference. "you want to build a framework, then consider this, this and this pattern". also giving some examples. then jumps to another implementation eg. search engine and gives some patterns and concrete examples to use. in this way you learn about the weakness and strength about each pattern and where they will fit, instead of just reading about every design pattern decoupled from each other. are there good "reference sheets" or other tutorials good for a beginner at this? thanks

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  • paket drop and splits in udp tunnel

    - by sr-dusad
    hi guys ! Currently I am working on video conferencing project.For this i m using pwnat for nat traversing. pwnat is based on udp tunneling.I m using the TCP connection for data transmission. My problem is that when i send a packet , it does not reach properly at its destination side . Sometime it drops the packet and many times it breaks ( split ) the packet into pieces. Please Help me .. How can i send and recieve a packet into single piece. So, i can draw image properly and play sound. Any kind of help will be appriciated . Thanks in advance

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  • Using pointers, references, handles to generic datatypes, as generic and flexible as possible

    - by Patrick
    In my application I have lots of different data types, e.g. Car, Bicycle, Person, ... (they're actually other data types, but this is just for the example). Since I also have quite some 'generic' code in my application, and the application was originally written in C, pointers to Car, Bicycle, Person, ... are often passed as void-pointers to these generic modules, together with an identification of the type, like this: Car myCar; ShowNiceDialog ((void *)&myCar, DATATYPE_CAR); The 'ShowNiceDialog' method now uses meta-information (functions that map DATATYPE_CAR to interfaces to get the actual data out of Car) to get information of the car, based on the given data type. That way, the generic logic only has to be written once, and not every time again for every new data type. Of course, in C++ you could make this much easier by using a common root class, like this class RootClass { public: string getName() const = 0; }; class Car : public RootClass { ... }; void ShowNiceDialog (RootClass *root); The problem is that in some cases, we don't want to store the data type in a class, but in a totally different format to save memory. In some cases we have hundreds of millions of instances that we need to manage in the application, and we don't want to make a full class for every instance. Suppose we have a data type with 2 characteristics: A quantity (double, 8 bytes) A boolean (1 byte) Although we only need 9 bytes to store this information, putting it in a class means that we need at least 16 bytes (because of the padding), and with the v-pointer we possibly even need 24 bytes. For hundreds of millions of instances, every byte counts (I have a 64-bit variant of the application and in some cases it needs 6 GB of memory). The void-pointer approach has the advantage that we can almost encode anything in a void-pointer and decide how to use it if we want information from it (use it as a real pointer, as an index, ...), but at the cost of type-safety. Templated solutions don't help since the generic logic forms quite a big part of the application, and we don't want to templatize all this. Additionally, the data model can be extended at run time, which also means that templates won't help. Are there better (and type-safer) ways to handle this than a void-pointer? Any references to frameworks, whitepapers, research material regarding this?

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