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  • How to learn a language that has very little coverage?

    - by bennybdbc
    I recently came across the Kogut language, and was interested by it. However, the only website to gain information from is the sourceforge page that hosts the project. I had no idea how to even attempt to look at the language in more depth. So what I'm asking is, has anyone here learnt a language that doesn't have the thousands of resources that Ruby, Python etc. have? What would be the best method to do so?

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  • Error in my OO Generics design. How do I workaround it?

    - by John
    I get "E2511 Type parameter 'T' must be a class type" on the third class. type TSomeClass=class end; ParentParentClass<T>=class end; ParentClass<T: class> = class(ParentParentClass<T>) end; ChildClass<T: TSomeClass> = class(ParentClass<T>) end; I'm trying to write a lite Generic Array wrapper for any data type(ParentParentClass) ,but because I'm unable to free type idenitifiers( if T is TObject then Tobject(T).Free) , I created the second class, which is useful for class types, so I can free the objects. The third class is where I use my wrapper, but the compiler throws that error. How do I make it compile?

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  • Supporting Piping (A Useful Hello World)

    - by blastthisinferno
    I am trying to write a collection of simple C++ programs that follow the basic Unix philosophy by: Make each program do one thing well. Expect the output of every program to become the input to another, as yet unknown, program. I'm having an issue trying to get the output of one to be the input of the other, and getting the output of one be the input of a separate instance of itself. Very briefly, I have a program add which takes arguments and spits out the summation. I want to be able to pipe the output to another add instance. ./add 1 2 | ./add 3 4 That should yield 6 but currently yields 10. I've encountered two problems: The cin waits for user input from the console. I don't want this, and haven't been able to find a simple example showing a the use of standard input stream without querying the user in the console. If someone knows of an example please let me know. I can't figure out how to use standard input while supporting piping. Currently, it appears it does not work. If I issue the command ./add 1 2 | ./add 3 4 it results in 7. The relevant code is below: add.cpp snippet // ... COMMAND LINE PROCESSING ... std::vector<double> numbers = multi.getValue(); // using TCLAP for command line parsing if (numbers.size() > 0) { double sum = numbers[0]; double arg; for (int i=1; i < numbers.size(); i++) { arg = numbers[i]; sum += arg; } std::cout << sum << std::endl; } else { double input; // right now this is test code while I try and get standard input streaming working as expected while (std::cin) { std::cin >> input; std::cout << input << std::endl; } } // ... MORE IRRELEVANT CODE ... So, I guess my question(s) is does anyone see what is incorrect with this code in order to support piping standard input? Are there some well known (or hidden) resources that explain clearly how to implement an example application supporting the basic Unix philosophy? @Chris Lutz I've changed the code to what's below. The problem where cin still waits for user input on the console, and doesn't just take from the standard input passed from the pipe. Am I missing something trivial for handling this? I haven't tried Greg Hewgill's answer yet, but don't see how that would help since the issue is still with cin. // ... COMMAND LINE PROCESSING ... std::vector<double> numbers = multi.getValue(); // using TCLAP for command line parsing double sum = numbers[0]; double arg; for (int i=1; i < numbers.size(); i++) { arg = numbers[i]; sum += arg; } // right now this is test code while I try and get standard input streaming working as expected while (std::cin) { std::cin >> arg; std::cout << arg << std::endl; } std::cout << sum << std::endl; // ... MORE IRRELEVANT CODE ...

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  • Any merit to a lazy-ish juxt function?

    - by NielsK
    In answering a question about a function that maps over multiple functions with the same arguments (A: juxt), I came up with a function that basically took the same form as juxt, but used map: (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply %1 %2) funs (repeat args)))) => ((juxt inc dec str) 1) [2 0 "1"] => ((could-be-lazy-juxt inc dec str) 1) (2 0 "1") => ((juxt * / -) 6 2) [12 3 4] => ((could-be-lazy-juxt * / -) 6 2) (12 3 4) As posted in the original question, I have little clue about the laziness or performance of it, but timing in the REPL does suggest something lazy-ish is going on. => (time (apply (juxt + -) (range 1 100))) "Elapsed time: 0.097198 msecs" [4950 -4948] => (time (apply (could-be-lazy-juxt + -) (range 1 100))) "Elapsed time: 0.074558 msecs" (4950 -4948) => (time (apply (juxt + -) (range 10000000))) "Elapsed time: 1019.317913 msecs" [49999995000000 -49999995000000] => (time (apply (could-be-lazy-juxt + -) (range 10000000))) "Elapsed time: 0.070332 msecs" (49999995000000 -49999995000000) I'm sure this function is not really that quick (the print of the outcome 'feels' about as long in both). Doing a 'take x' on the function only limits the amount of functions evaluated, which probably is limited in it's applicability, and limiting the other parameters by 'take' should be just as lazy in normal juxt. Is this juxt really lazy ? Would a lazy juxt bring anything useful to the table, for instance as a compositing step between other lazy functions ? What are the performance (mem / cpu / object count / compilation) implications ? Is that why the Clojure juxt implementation is done with a reduce and returns a vector ? Edit: Somehow things can always be done simpler in Clojure. (defn could-be-lazy-juxt [& funs] (fn [& args] (map #(apply % args) funs)))

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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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  • 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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  • What are these lines doing?

    - by Montecristo
    I'm starting learning javascript for a project, I've found a script that does a part of what I need to do, I'd like to know how it works, both for me and in case it needs to be modified. Originally it was used inside the page, now I've put it in a file on its own and does not work anymore, so I'm dividing it in parts, because I fail to get the whole thing. Here is what bother me most for now: 1) Is this a declaration a function? What is its name? How can it be invoked? (function() { //some code })(); 2) No clue of what is going on here var VARIABLE = VARIABLE || {}; 3) Am I defining a the implementation of methodCall here? Something like overriding a method in Java? VARIABLE.methodCall = function(parameter) { console.log("parameter was: " + parameter); }; Thank you in advance for your help.

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  • How to automatically run in the background?

    - by Hun1Ahpu
    I'm not sure that it's not implemented yet, I hope that it is. But I know that in .Net programmers should manually run time-consuming task in the background thread. So every time we handle some UI event and we understand that this will take some time we also understand that this will hang UI thread and our application. And then we make all this Background work things and handle callbacks or whatever. So my question is: Is there in some language/platform a mechanism that will automatically run time-consuming tasks in the background and will do all related work itself? So we just write the code for handling specific UI event and this code will be somehow detected as time-consuming and will be executed in background. And if there isn't, then why?

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  • Which header files are necessary to run this code snippet?

    - by httpinterpret
    It's from here,but fails when compiling: int main(int argc, char **argv) { struct hostent { char *h_name; // main name char **h_aliases; // alternative names (aliases) int h_addrtype; // address type (usually AF_INET) int h_length; // length of address (in octets) char **h_addr_list; // alternate addresses (in Network Byte Order) }; #define h_addr h_addr_list[0] // First address of h_addr_list. struct hostent *info_stackoverflow; int i = 0; info_stackoverflow = gethostbyname( "www.stackoverflow.com" ); printf("The IP address of %s is %s", info_stackoverflow->h_name, inet_ntoa( * ((struct in_addr *)info_stackoverflow->h_addr ))); /* aliases */ while( *(pc_ip->h_aliases + i) != NULL ) { printf("\n\tAlias: %s", *(pc_ip->h_aliases + i) ); i++; } }

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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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  • 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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  • C++ String manipulation isn't making sense to me...

    - by Andrew Bolster
    I am trying some of the Stanford SEE courses online to learn some new languages; this particular assignment has to do with removing substrings from strings. What I've got so far is below, but if text = "hello hello" and remove ="el", it gets stuck in a loop, but if i change text to text = "hello hllo", it works, making me think I'm doing something obviously stupid. There is a stipulation in the assignment not to modify the incoming strings, and instead to return a new string. string CensorString1(string text, string remove){ string returned; size_t found=0, lastfound=0; found = (text.substr(lastfound,text.size())).find(remove); while (string::npos != found ){ returned += text.substr(lastfound,found); lastfound = found + remove.size(); found = (text.substr(lastfound,text.size())).find(remove); } returned += text.substr(lastfound,found); return returned; } Guidance would be appreciated :-) Thanks

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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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  • What is the Software Development Lifecycle?

    - by j-t-s
    Our investor wants a SDLC. I've never written one before, and I don't have enough time to go and buy a book, or spend much time learning about them. From what I've been told about them, they consist of requirements (what needs to be done), and a list is done. Is this correct? Update: I have found this article which really helps to explain things in simple terms and very quickly. Not that I think an SDLC should be done quickly. In my case, I have no other option.

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  • Manifesto for Integrated Development Environments

    - by Hugo S Ferreira
    Have you recently take a peek at Coda, or Espresso, or Textmate? Or even Google Chrome's Developer Tools? They are well designed, intuitive, interface rich, and extensible. But Coda, Espresso or Textmate, among several, are text editors, not IDEs. On the other side, VIM and Emacs live in the last century, and Eclipse is an overbloated platform. This is more like an outcry for a decent, common infrastructure for REAL IDEs. But there's some questions attached: (i) what features are needed for such a product and (ii) what products are out there that could fullfil this need, and what are they missing. So here's my draft for a manifesto: Manifesto for Integrated Development Environments: We favor interactivity and productivity over syntax and tools. We favor inline, contextual documentation over man and html files. We favor high-definition, graphic-capable color screens over 80x25 character terminals. We favor the use of advanced input schemas over unintuitive keyboard shortcuts. We favor a common, extensible and customizable infrastructure over unmaintained chaintools. We know the difference between search&replace and refactoring. We know the difference between integrated debugging support over a terminal window. We know the difference between semantic-aware code-completion over dumb textual templates. We favor the usage of standards like (E)BNF.

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  • Is it possible to have more than P2P on iPhone with Bluetooth

    - by Ricardo Ferreira
    Hi all, This seems like a straightforward google search answer, but after a while, I still can't be 100% sure of this. I've found Z2Live (http://www.z2live.com/), which is basically a layer above GameKit and they too use only P2P with Bluetooth. So I just want to be sure if I can only have P2P with Bluetooth or if I can have like 4 iPhones all connected to a server (who will also be a client) using Bluetooth. Thanks in advance.

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  • How to use boost::transform_iterator to iterate over modifed std::map values?

    - by Frank
    I have an std::map, and I would like to define an iterator that returns modified values. Typically, a std::map<int,double>::iterator iterates over std::pair<int,double>, and I would like the same behavior, just the double value is multiplied by a constant. I tried it with boost::transform_iterator, but it doesn't compile: #include <map> #include <boost/iterator/transform_iterator.hpp> #include <boost/functional.hpp> typedef std::map<int,double> Map; Map m; m[100] = 2.24; typedef boost::binder2nd< std::multiplies<double> > Function; typedef boost::transform_iterator<Function, Map::value_type*> MultiplyIter; MultiplyIter begin = boost::make_transform_iterator(m.begin(), Function(std::multiplies<double>(), 4)); // now want to similarly create an end iterator // and then iterate over the modified map The error is: error: conversion from 'boost ::transform_iterator< boost::binder2nd<multiplies<double> >, gen_map<int, double>::iterator , boost::use_default, boost::use_default >' to non-scalar type 'boost::transform_iterator< boost::binder2nd<multiplies<double> >, pair<const int, double> * , boost::use_default, boost::use_default >' requested What is gen_map and do I really need it? I adapted the transform_iterator tutorial code from here to write this code ...

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  • what is the programmatic parlance for this phenomenon?

    - by deostroll
    Here is javascript code (jquery) for adding a row of images: var tr = $('<tr>'); var td = '<td><img src="myimg.jpg"/></td>'; tr.append(td).append(td).append(td); $('#mytable tbody tr:eq(0)').before(tr); tr.empty(); //I really don't need this line... Technically tr.empty() shouldn't have worked. It actually does the opposite of what I want. What is the techinical term for this behaviour - You've added tr to the DOM, but any jquery function calls to that object still works, where as you'd normally not expect it to work i.e. make changes to the DOM?

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  • Using Cases to change background colour | Visual Studio 2008

    - by Simon
    I really need help working with cases, I'm only learning it so far, but just can't get a drop down menu to work that would change the background of a Textbox. Private Sub cbColours_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbColours.SelectedIndexChanged Select Case colours Case Is = "Red" txtSpace.BackColor = Color.Red Case Is = "Blue" txtSpace.BackColor = Color.Blue Case Is = "Green" txtSpace.BackColor = Color.Green End Select End Sub It isn't doing anything at all... In the dropdown menu, it has Red, Blue and Green one per line When the value (e.g. Green) is clicked, it will then change the Textbox to the colour selected. Many help appreciated :)

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  • Function Composition in C++

    - by Channel72
    There are a lot of impressive Boost libraries such as Boost.Lambda or Boost.Phoenix which go a long way towards making C++ into a truly functional language. But is there a straightforward way to create a composite function from any 2 or more arbitrary functions or functors? If I have: int f(int x) and int g(int x), I want to do something like f . g which would statically generate a new function object equivalent to f(g(x)). This seems to be possible through various techniques, such as those discussed here. Certainly, you can chain calls to boost::lambda::bind to create a composite functor. But is there anything in Boost which easily allows you to take any 2 or more functions or function objects and combine them to create a single composite functor, similar to how you would do it in a language like Haskell?

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