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  • Interview question: difference between object and object-oriented languages.

    - by Bar
    My friend was asked the following question: what's the difference between object language and object-oriented language? It's a little unintelligible question. What does term «object language» correspond to? Does that mean «pure» object-oriented language, like the Wikipedia article says: Languages called "pure" OO languages, because everything in them is treated consistently as an object, from primitives such as characters and punctuation, all the way up to whole classes, prototypes, blocks, modules, etc. They were designed specifically to facilitate, even enforce, OO methods. Examples: Smalltalk, Eiffel, Ruby, JADE, VB.NET.

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  • Appropriate high level language to deal with binary data

    - by fortran
    Hi, I need to write a small tool that parses a textual input and generates some binary encoded data. I would prefer to stay away from C and the like, in favour of a higher level, (optionally) safer, more expressive and faster to develop language. My language of choice for this kind of tasks usually is Python, but for this case dealing with binary raw data can be problematic if one isn't very careful with the numbers being promoted to bignums, sign extensions and such. Ideally I would like to have records with named bitfields that are portable to be serialised in a consistent manner. (I know that there's a strong point in doing it in a language I already master, although it isn't optimal, but I think this could be a good opportunity to learn something new). Thanks.

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  • java statistics collection for performance evaluation

    - by user384706
    What is the most efficient way to collect and report performance statistic analysis from an application? If I have an application that uses a series of network apis, and I want to report statistics at runtime, e.g. Method doA() was called 3 times and consumed on avg 500ms Method doB() was called 5 times and consumed on avg 1200ms etc Then, I thought of using a well defined data structure (of collection) that each thread updates per remote call, and this can be used for the report. But I think that it will make the performance worse, for the time spend for statistics collection. Am I correct? How would I procceed if I used a background thread for this, and the other threads that did the remote calls were unaware of this collection gathering? Thanks

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  • Is there a suitable replacement for C++, when I would like to write video processing applications?

    - by Nisanio
    Hi I want to write a video editing software, and the "logical" conclusion is that the language I must to use is C++... But I don't like it (sorry c++ fans) I would like to write it with something cool, like Lisp or Haskell or Erlang... But I don't know if the open source implementation of those languages (I don't have money to buy licenses) let me made a competitive software (in the performance area) What do you think? what do you recommend?

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  • Mapping over multiple Seq in Scala

    - by bsdfish
    Suppose I have val foo : Seq[Double] = ... val bar : Seq[Double] = ... and I wish to produce a seq where the baz(i) = foo(i) + bar(i). One way I can think of to do this is val baz : Seq[Double] = (foo.toList zip bar.toList) map ((f: Double, b : Double) => f+b) However, this feels both ugly and inefficient -- I have to convert both seqs to lists (which explodes with lazy lists), create this temporary list of tuples, only to map over it and let it be GCed. Maybe streams solve the lazy problem, but in any case, this feels like unnecessarily ugly. In lisp, the map function would map over multiple sequences. I would write (mapcar (lambda (f b) (+ f b)) foo bar) And no temporary lists would get created anywhere. Is there a map-over-multiple-lists function in Scala, or is zip combined with destructuring really the 'right' way to do this?

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  • How do "modern JVMs" differ from older JVMs?

    - by Lord Torgamus
    Here's a phrase that I heard a lot throughout high school and university computer science classes: "That's not an issue for modern JVMs." Usually this would come up in discussions about overall performance or optimization strategies. It was always treated as a kind of magical final answer, though, as if it makes issues no longer worth thinking about. And that just leads me to wonder: what are the differences between the prototypical "modern JVM" and older JVMs, really?

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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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  • sending a packet to multiple client at a time from udp socket

    - by mawia
    Hi! all, I was trying to write a udp server who send an instance of a file to multiple clients.Now suppose any how I manage to know the address of those client statically(for the sake of simplicity) and now I want to send this packet to these addresses.So how exactly I need to fill the sockaddr structure to contain the address of these clients.I am taking an array of sockaddr structure(to contain client address) and trying to send at each one them at a time.Now problem is to fill the individual sockaddr structure to contain the client address. I was trying to do something like that sa[1].sin_family = AF_INET; sa[1].sin_addr.s_addr = htonl(INADDR_ANY);//should'nt I replace this INADDR_ANY with client ip?? sa[1].sin_port = htons(50002); Correct me if this is not the correct way. All your help in this regard will be highly appreciated. With Thanks in advance, Mawia

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  • warcraft3 packet infromation [closed]

    - by ajay009ajay
    Hello All, I have made a program which is fetching data from server to and game to server. I want to keep these record in my file. But my problem is this is not in good format that i can read easily. I am reading all data as "Byte" (from java). Can anybody explain header or data info of packet. so I can read it in human manner Huh thanks.

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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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  • Efficient algorithm to distribute work?

    - by Zwei Steinen
    It's a bit complicated to explain but here we go. We have problems like this (code is pseudo-code, and is only for illustrating the problem. Sorry it's in java. If you don't understand, I'd be glad to explain.). class Problem { final Set<Integer> allSectionIds = { 1,2,4,6,7,8,10 }; final Data data = //Some data } And a subproblem is: class SubProblem { final Set<Integer> targetedSectionIds; final Data data; SubProblem(Set<Integer> targetedSectionsIds, Data data){ this.targetedSectionIds = targetedSectionIds; this.data = data; } } Work will look like this, then. class Work implements Runnable { final Set<Section> subSections; final Data data; final Result result; Work(Set<Section> subSections, Data data) { this.sections = SubSections; this.data = data; } @Override public void run(){ for(Section section : subSections){ result.addUp(compute(data, section)); } } } Now we have instances of 'Worker', that have their own state sections I have. class Worker implements ExecutorService { final Map<Integer,Section> sectionsIHave; { sectionsIHave = {1:section1, 5:section5, 8:section8 }; } final ExecutorService executor = //some executor. @Override public void execute(SubProblem problem){ Set<Section> sectionsNeeded = fetchSections(problem.targetedSectionIds); super.execute(new Work(sectionsNeeded, problem.data); } } phew. So, we have a lot of Problems and Workers are constantly asking for more SubProblems. My task is to break up Problems into SubProblem and give it to them. The difficulty is however, that I have to later collect all the results for the SubProblems and merge (reduce) them into a Result for the whole Problem. This is however, costly, so I want to give the workers "chunks" that are as big as possible (has as many targetedSections as possible). It doesn't have to be perfect (mathematically as efficient as possible or something). I mean, I guess that it is impossible to have a perfect solution, because you can't predict how long each computation will take, etc.. But is there a good heuristic solution for this? Or maybe some resources I can read up before I go into designing? Any advice is highly appreciated!

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  • Are raw C++ pointers first class objects?

    - by Shailesh Kumar
    According to Wikipedia: An object is first-class when it: can be stored in variables and data structures can be passed as a parameter to a subroutine can be returned as the result of a subroutine can be constructed at runtime has intrinsic identity (independent of any given name) Somebody had once told me that raw pointers are not first class objects while smart pointers like std::auto_ptr are. But to me, a raw pointer (to an object or to a function) in C++ does seem to me to satisfy the conditions stated above to qualify as a first class object. Am I missing something?

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  • How can programmers get the quiet working environment they need? [closed]

    - by Richard
    We have an open plan office with all our programmers, web designers and client service team. Problem is my programmer team has to put up with dance music and wailing guitars all day due to the fact that designers and client services team think this makes the office a better environment. When I turn it off (by blocking the streaming of music on the router, he-he-he) they complain that its so quiet and dull. How do I explain to them that programmers need a calm quiet environment without coming across like a really annoying geek? Any other thoughts or ideas appreciated.

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  • How can I dial the default connection on Pocket PC 2003 ?

    - by Jalil
    I am working on a PPC2003 application. The devices on which the application has to run have a modem and VPN connection set. I want to automatically dial the system default "work" connection, which is the VPN one, which dial the modem one first. The user has another application who does automatically make the system dial the default connection. But I can't undertand how to do it from my Compact .NET application. I tried using OpenNETCF net package, but I could not make it work.

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  • My python program always brings down my internet connection after several hours running, how do I debug and fix this problem?

    - by Shane
    I'm writing a python script checking/monitoring several server/websites status(response time and similar stuff), it's a GUI program and I use separate thread to check different server/website, and the basic structure of each thread is using an infinite while loop to request that site every random time period(15 to 30 seconds), once there's changes in website/server each thread will start a new thread to do a thorough check(requesting more pages and similar stuff). The problem is, my internet connection always got blocked/jammed/messed up after several hours running of this script, the situation is, from my script side I got urlopen error timed out each time it's requesting a page, and from my FireFox browser side I cannot open any site. But the weird thing is, the moment I close my script my Internet connection got back on immediately which means now I can surf any site through my browser, so it must be the script causing all the problem. I've checked the program carefully and even use del to delete any connection once it's used, still get the same problem. I only use urllib2, urllib, mechanize to do network requests. Anybody knows why such thing happens? How do I debug this problem? Is there a tool or something to check my network status once such situation occurs? It's really bugging me for a while... By the way I'm behind a VPN, does it have something to do with this problem? Although I don't think so because my network always get back on once the script closed, and the VPN connection never drops(as it appears) during the whole process.

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  • functional, bind1st and mem_fun

    - by Neil G
    Why won't this compile? #include <functional> #include <boost/function.hpp> class A { A() { typedef boost::function<void ()> FunctionCall; FunctionCall f = std::bind1st(std::mem_fun(&A::process), this); } void process() {} }; Errors: In file included from /opt/local/include/gcc44/c++/bits/stl_function.h:712, from /opt/local/include/gcc44/c++/functional:50, from a.cc:1: /opt/local/include/gcc44/c++/backward/binders.h: In instantiation of 'std::binder1st<std::mem_fun_t<void, A> >': a.cc:7: instantiated from here /opt/local/include/gcc44/c++/backward/binders.h:100: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:103: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:106: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:111: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h:117: error: no type named 'second_argument_type' in 'class std::mem_fun_t<void, A>' /opt/local/include/gcc44/c++/backward/binders.h: In function 'std::binder1st<_Operation> std::bind1st(const _Operation&, const _Tp&) [with _Operation = std::mem_fun_t<void, A>, _Tp = A*]': a.cc:7: instantiated from here /opt/local/include/gcc44/c++/backward/binders.h:126: error: no type named 'first_argument_type' in 'class std::mem_fun_t<void, A>' In file included from /opt/local/include/boost/function/detail/maybe_include.hpp:13, from /opt/local/include/boost/function/detail/function_iterate.hpp:14, from /opt/local/include/boost/preprocessor/iteration/detail/iter/forward1.hpp:47, from /opt/local/include/boost/function.hpp:64, from a.cc:2: /opt/local/include/boost/function/function_template.hpp: In static member function 'static void boost::detail::function::void_function_obj_invoker0<FunctionObj, R>::invoke(boost::detail::function::function_buffer&) [with FunctionObj = std::binder1st<std::mem_fun_t<void, A> >, R = void]': /opt/local/include/boost/function/function_template.hpp:913: instantiated from 'void boost::function0<R>::assign_to(Functor) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' /opt/local/include/boost/function/function_template.hpp:722: instantiated from 'boost::function0<R>::function0(Functor, typename boost::enable_if_c<boost::type_traits::ice_not::value, int>::type) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' /opt/local/include/boost/function/function_template.hpp:1064: instantiated from 'boost::function<R()>::function(Functor, typename boost::enable_if_c<boost::type_traits::ice_not::value, int>::type) [with Functor = std::binder1st<std::mem_fun_t<void, A> >, R = void]' a.cc:7: instantiated from here /opt/local/include/boost/function/function_template.hpp:153: error: no match for call to '(std::binder1st<std::mem_fun_t<void, A> >) ()'

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  • Reason for not properly closed socket?

    - by gc
    Here is what I am trying to do: The server sends message to connected clients when new messages are available. The client, on the other hand, when connected, tries to send a message to the server using send() and then receive message using recv(), right after that, the client calls close() to close the connection. Sometimes, after the client finishes, the server tries to receive message from client will result in a 104 - "connection reset by peer" error. When this happens, Wireshark reveals that the last two segments sent by the client is: 1. an ACK acknowledging the receipt of the message sent by the server 2. a RST/ACK No FIN is sent by the client. Why is this happening and how can I close the socket "properly" at the client?

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  • What language/compiler for native running of application in any windows(XP/Vista/7) platform?

    - by Xinxua
    Hi, I want to develop an application that runs on any windows platform (XP, Vista, 7) but does not require a dependency like .NET Framework or JVM. I have given the other requirements below: Runs in any windows platform Must have GUI libraries to create windows/primitive controls I also want the output file size of the application to be minimal (So cannot include .net frameword etc in the exe file) Any suggestions for this requirement?

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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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