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  • Is there a variable in Rails that equates to the template that is being rendered?

    - by Sean Ahrens
    I can do request.path_parameters['controller'] and request.path_parameters['action'], but is there anything like request.path_parameters['template'] so I can discern which template file (such as index.html.erb) is being rendered? I'm writing a method that automatically sets the body id to the template being rendered, for easy css manipulation: class ApplicationController < ActionController::Base ... after_filter :define_body_selector ... def define_body_selector # sets @body_id to the name of the template that will be rendered # ie. if users/index.html.erb was just rendered, @body_id gets set to "index" @body_id = ??? end ...

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  • What will be the value of i in the following pseudocode?

    - by user283403
    I got this question in a programming test. Do you think this question is even correct? Look at the answer choices. (2^x means 2 raised to x) Consider the following pseudocode. x := 1; i := 1; while (x = 1000) begin x := 2^x; i := i + 1; end; What is the value of i at the end of the pseudocode? a) 4 b) 5 c) 6 d) 7 e) 8 I am sure that the value of i will 1. I told the examiner of the discrepancy and he advised me the leave the question unanswered if I felt it was incorrect. What else could I have done?

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  • How to create a Windows GUI with a file explorer window, allowing users to choose files?

    - by Badri
    Here's what I want to do. I want to present a file explorer, and allow the user to select files, and list the selected files below. (I then want to process those files but that's the next part) For example, the way CD Burning softwares work. I have created a mock up here http://dl.dropbox.com/u/113967/Mockup.png As you can see, the left frame has a directory structure, the right frame has a file selected, and the bottom frame shows the selected file. What framework can I go about creating this? I am familiar with command line C++ stuff, but I haven't ventured into any GUI programming, and figured this idea would be a good place to start. Any suggestions on where to start?

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  • How can variadic char template arguments from user defined literals be converted back into numeric types?

    - by Pubby
    This question is being asked because of this one. C++11 allows you to define literals like this for numeric literals: template<char...> OutputType operator "" _suffix(); Which means that 503_suffix would become <'5','0','3'> This is nice, although it isn't very useful in the form it's in. How can I transform this back into a numeric type? This would turn <'5','0','3'> into a constexpr 503. Additionally, it must also work on floating point literals. <'5','.','3> would turn into int 5 or float 5.3 A partial solution was found in the previous question, but it doesn't work on non-integers: template <typename t> constexpr t pow(t base, int exp) { return (exp > 0) ? base * pow(base, exp-1) : 1; }; template <char...> struct literal; template <> struct literal<> { static const unsigned int to_int = 0; }; template <char c, char ...cv> struct literal<c, cv...> { static const unsigned int to_int = (c - '0') * pow(10, sizeof...(cv)) + literal<cv...>::to_int; }; // use: literal<...>::to_int // literal<'1','.','5'>::to_int doesn't work // literal<'1','.','5'>::to_float not implemented

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  • question about c++ template functions taking any type as long that type meets at least one of the re

    - by smerlin
    Since i cant explain this very well, i will start with a small example right away: template <class T> void Print(const T& t){t.print1();} template <class T> void Print(const T& t){t.print2();} This does not compile: error C2995: 'void Print(const T &)' : function template has already been defined So, how can i create a template function which takes any type T as long as that type has a print1 memberfunction OR a print2 memberfunction (no polymorphism) ?

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  • How do I change careers to become a programmer without spending a lot of money

    - by bgc83
    I'm currently a network engineer, but find myself wanting to get into the world of development. I took a little bit of Java in college, am 27 years old and have been network engineering for 4 years now. I have a mortgage and student loans so going back to school would be difficult. I'm willing to put in however much hardwork is needed around my full time job to learn, but part of me feels I may need actuall schooling to get down some of the advanced concepts. Just looking for a little advice and direction. I have purchased a bunch of the Head First programming books and have begun reading through some of them as I figure out my way into this transition.

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  • Given a number N, find the number of ways to write it as a sum of two or more consecutive integers

    - by hilal
    Here is the problem (Given a number N, find the number of ways to write it as a sum of two or more consecutive integers) and example 15 = 7+8, 1+2+3+4+5, 4+5+6 I solved with math like that : a + (a + 1) + (a + 2) + (a + 3) + ... + (a + k) = N (k + 1)*a + (1 + 2 + 3 + ... + k) = N (k + 1)a + k(k+1)/2 = N (k + 1)*(2*a + k)/2 = N Then check that if N divisible by (k+1) and (2*a+k) then I can find answer in O(N) time Here is my question how can you solve this by dynamic-programming ? and what is the complexity (O) ? P.S : excuse me, if it is a duplicate question. I searched but I can find

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  • No "redefinition of default parameter error" for class template member function?

    - by STingRaySC
    Why does the following give no compilation error?: // T.h template<class T> class X { public: void foo(int a = 42); }; // Main.cpp #include "T.h" #include <iostream> template<class T> void X<T>::foo(int a = 13) { std::cout << a << std::endl; } int main() { X<int> x; x.foo(); // prints 42 } It seems as though the 13 is just silently ignored by the compiler. Why is this? The cooky thing is that if the template declaration is in Main.cpp instead of a header file, I do indeed get the default parameter redefinition error. Now I know the compiler will complain about this if it were just an ordinary (non-template) function. What does the standard have to say about default parameters in class template member functions or function templates?

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  • Play! Framework - Can my view template be localised when rendering it as an AsyncResult?

    - by avik
    I've recently started using the Play! framework (v2.0.4) for writing a Java web application. In the majority of my controllers I'm following the paradigm of suspending the HTTP request until the promise of a web service response has been fulfilled. Once the promise has been fulfilled, I return an AsyncResult. This is what most of my actions look like (with a bunch of code omitted): public static Result myActionMethod() { Promise<MyWSResponse> wsResponse; // Perform a web service call that will return the promise of a MyWSResponse... return async(wsResponse.map(new Function<MyWSResponse, Result>() { @Override public Result apply(MyWSResponse response) { // Validate response... return ok(myScalaViewTemplate.render(response.data())); } })); } I'm now trying to internationalise my app, but hit the following error when I try to render a template from an async method: [error] play - Waiting for a promise, but got an error: There is no HTTP Context available from here. java.lang.RuntimeException: There is no HTTP Context available from here. at play.mvc.Http$Context.current(Http.java:27) ~[play_2.9.1.jar:2.0.4] at play.mvc.Http$Context$Implicit.lang(Http.java:124) ~[play_2.9.1.jar:2.0.4] at play.i18n.Messages.get(Messages.java:38) ~[play_2.9.1.jar:2.0.4] at views.html.myScalaViewTemplate$.apply(myScalaViewTemplate.template.scala:40) ~[classes/:na] at views.html.myScalaViewTemplate$.render(myScalaViewTemplate.template.scala:87) ~[classes/:na] at views.html.myScalaViewTemplate.render(myScalaViewTemplate.template.scala) ~[classes/:na] In short, where I've got a message bundle lookup in my view template, some Play! code is attempting to access the original HTTP request and retrieve the accept-languages header, in order to know which message bundle to use. But it seems that the HTTP request is inaccessible from the async method. I can see a couple of (unsatisfactory) ways to work around this: Go back to the 'one thread per request' paradigm and have threads block waiting for responses. Figure out which language to use at Controller level, and feed that choice into my template. I also suspect this might not be an issue on trunk. I know that there is a similar issue in 2.0.4 with regards to not being able to access or modify the Session object which has recently been fixed. However I'm stuck on 2.0.4 for the time being, so is there a better way that I can resolve this problem?

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  • Write the longest possible loop.

    - by Abhay
    Hello Group, Recently I was asked this question in a technical discussion. What is the longest possible loop that can be written in a programming language? This loop has to be as long as possible and yet not an infinite loop and should not end-up crashing the program (Recursion etc...) I honestly did not know how to attack this problem, so I asked him if is it practically possible. He said using some computer science concepts, you can arrive at a hypothetical number which may not be practical but nevertheless it will still not be infinite. Anyone here; knows how to analyse / attack this problem. P.S. Choosing some highest limit for a type that can store the highest numerical value is apparently not an answer. Thanks in advance,

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  • Why should I use a web framework's template language over python's templating options?

    - by stariz77
    I'm coming from a python CGI background and was wanting to move into something more contemporary and think I have decided upon web.py as the framework I would like to use. In regards to templating, previously I used formatted strings and the string.Template module to effect most of my templating needs. After reading through a few of the templating options I have heard mentioned, I began wondering what the main benefits of using something like the Django or jinja templating options over "native" Python templating options were? Am I just going to be replacing $tmpl_var with {{ tmpl_var }} and s.substitute(tmpl_var=value) with t.render(s), i.e., alternate syntax? or will I gain additional advantages from using these templating systems?

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  • In which language the KIS application might have been developed??

    - by Jeba
    Hello all, I just went through this link http://www.pcauthority.com.au/Feature/91093,the-tsar-of-antivirus.aspx and found that it's developed using c/c++ and visual studio with a little assembly language support. As a programmer i just want to know in what programming language the kaspersky internet security User Interface(UI) has been developed? Might be using QT(coz. of c++)? or using MFC(coz. of visual studio)?? With side tab like thing the UI looks good. Expecting the answers from expert analysts.

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  • Clojure for a lisp illiterate

    - by dbyrne
    I am a lifelong object-oriented programmer. My job is primarily java development, but I have experience in a number of languages. Ruby gave me my first real taste of functional programming. I loved the features Ruby borrowed from the functional paradigm such as closures and continuations. Eventually, I graduated to Scala. This has been a great way to gradually learn to approach non-trivial problems in a functional manner. Now I am interested in Clojure. I know all the sexy features that make it enticing (software transactional memory, macros, etc.), but I just can't get used to "thinking in lisp". I've seen Rich Hickey's screencasts aimed at java programmers, but they are geared towards explaining language features and not approaching real world problems. I am looking for any advice or resources which have made this transition easier for others.

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  • Can you use #defined values in if statements (In C programs)?

    - by Jordan S
    I am new at C programming. I thought when you type something like #define Const 5000 that the compiler just replaces every instance of Const with 5000 at compile time. Is that wrong? I try doing this in my code and I get a syntax error. Why can't i do this? #define STEPS_PER_REV 12345 ... in some function if(CurrentPosition >= STEPS_PER_REV) { // do some stuff here } The compiler complains about the if statement with a syntax error that gives me no details.

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  • Best solution to wait for all ajax callbacks to be executed

    - by glaz666
    Hi! Imagine we have to sources to be requested by ajax. I want to perform some actions when all callbacks are triggered. How this can be done besides this approach: (function($){ var sources = ['http://source1.com', 'http://source2.com'], guard = 0, someHandler = function() { if (guard != sources.length) { return; } //do some actions }; for (var idx in sources) { $.getJSON(sources[idx], function(){ guard++; someHandler(); }) } })(jQuery) What I don't like here is that in this case I can't handle response failing (eg. I can't set timeout for response to come) and overall approach (I suppose there should be a way to use more power of functional programming here) Any ideas? Regards!

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  • Tips for measuring the parallelism speed-up in multi-core development.

    - by fnCzar
    I have read many of the good questions and answers around multi-core programming how-tos etc. I am familiar with concurrency, IPC, MPI etc but what I need is advice on how to measure speed-up which will help in making a business case of spending the time to write such code. Please don't answer with "well run it with single-core code then multi-core code and figure out the difference". This is neither a scientific nor a reliable way to measure performance improvement. If you know of tools that will do some of the heavy lifting please mention them. Answers pertaining to methodology will be more fitting but listing tools is ok as well.

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  • Is there a way of providing a final transform method when chaining operations (like map reduce) in underscore.js?

    - by latentflip
    (Really strugging to title this question, so if anyone has suggestions feel free.) Say I wanted to do an operation like: take an array [1,2,3] multiply each element by 2 (map): [2,4,6] add the elements together (reduce): 12 multiply the result by 10: 120 I can do this pretty cleanly in underscore using chaining, like so: arr = [1,2,3] map = (el) -> 2*el reduce = (s,n) -> s+n out = (r) -> 10*r reduced = _.chain(arr).map(map).reduce(reduce).value() result = out(reduced) However, it would be even nicer if I could chain the 'out' method too, like this: result = _.chain(arr).map(map).reduce(reduce).out(out).value() Now this would be a fairly simple addition to a library like underscore. But my questions are: Does this 'out' method have a name in functional programming? Does this already exist in underscore (tap comes close, but not quite).

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  • How to evaluate text strings provided by sed/grep/whatever?

    - by T.J.
    This is for UNIX shell programming. It have to be supported by multiple UNIX platforms including Solaris, Linux, and AIX. I have this scenario -- I am to read from a text file a string that may or may not contain an environment variable that may or may not be defined. For example: <foo.bar> This error code was found: $(error_code) I have the following code: statement=$(sed -n $1'p' $messagefile) echo $echo_flag $statement $1 = line number supplied to this particular function/script. $messagefile = filename of log file. $echo_flag = "-e" in Linux, otherwise, empty. $(error_code) = 42. Instead of getting this when running: <foo.bar> This error code was found: 42 I still get this: <foo.bar> This error code was found: $(error_code) How exactly do I tell the shell script that the value of statement should be evaluated further beyond what sed have done?

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  • client-server application design

    - by nelly
    Hi, i want to create a client-server application using sockets on .net platform and being new to networking programming and i have a dilemma. The client will send data to server often and also the server will notify clients often. What is the best way to design it? should the server keep a thread to communicate with each client until it quits or just the clients send data to the server and it update the clients regularly(few seconds) or none of those? Some help would be great. Thanks guys.

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  • How can I write a function template for all types with a particular type trait?

    - by TC
    Consider the following example: struct Scanner { template <typename T> T get(); }; template <> string Scanner::get() { return string("string"); } template <> int Scanner::get() { return 10; } int main() { Scanner scanner; string s = scanner.get<string>(); int i = scanner.get<int>(); } The Scanner class is used to extract tokens from some source. The above code works fine, but fails when I try to get other integral types like a char or an unsigned int. The code to read these types is exactly the same as the code to read an int. I could just duplicate the code for all other integral types I'd like to read, but I'd rather define one function template for all integral types. I've tried the following: struct Scanner { template <typename T> typename enable_if<boost::is_integral<T>, T>::type get(); }; Which works like a charm, but I am unsure how to get Scanner::get<string>() to function again. So, how can I write code so that I can do scanner.get<string>() and scanner.get<any integral type>() and have a single definition to read all integral types? Update: bonus question: What if I want to accept more than one range of classes based on some traits? For example: how should I approach this problem if I want to have three get functions that accept (i) integral types (ii) floating point types (iii) strings, respectively.

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  • Experiences teaching or learning map/reduce/etc before recursion?

    - by Jay
    As far as I can see, the usual (and best in my opinion) order for teaching iterting constructs in functional programming with Scheme is to first teach recursion and maybe later get into things like map, reduce and all SRFI-1 procedures. This is probably, I guess, because with recursion the student has everything that's necessary for iterating (and even re-write all of SRFI-1 if he/she wants to do so). Now I was wondering if the opposite approach has ever been tried: use several procedures from SRFI-1 and only when they are not enough (for example, to approximate a function) use recursion. My guess is that the result would not be good, but I'd like to know about any past experiences with this approach.

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  • template specialization for static member functions; howto?

    - by Rolle
    I am trying to implement a template function with handles void differently using template specialization. The following code gives me an "Explicit specialization in non-namespace scope" in gcc: template <typename T> static T safeGuiCall(boost::function<T ()> _f) { if (_f.empty()) throw GuiException("Function pointer empty"); { ThreadGuard g; T ret = _f(); return ret; } } // template specialization for functions wit no return value template <> static void safeGuiCall<void>(boost::function<void ()> _f) { if (_f.empty()) throw GuiException("Function pointer empty"); { ThreadGuard g; _f(); } } I have tried moving it out of the class (the class is not templated) and into the namespace but then I get the error "Explicit specialization cannot have a storage class". I have read many discussions about this, but people don't seem to agree how to specialize function templates. Any ideas?

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  • Javascript: best solution to wait for all ajax callbacks to be executed

    - by glaz666
    Hi! Imagine we have to sources to be requested by ajax. I want to perform some actions when all callbacks are triggered. How this can be done besides this approach: (function($){ var sources = ['http://source1.com', 'http://source2.com'], guard = 0, someHandler = function() { if (guard != sources.length) { return; } //do some actions }; for (var idx in sources) { $.getJSON(sources[idx], function(){ guard++; someHandler(); }) } })(jQuery) What I don't like here is that in this case I can't handle response failing (eg. I can't set timeout for response to come) and overall approach (I suppose there should be a way to use more power of functional programming here) Any ideas? Regards!

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  • Instantiating Java object with a passed in method

    - by superluminary
    It's been a few years since I've been heavily into Java. Coming back to it I'm seeing this pattern all over the place: ratingBar.setOnRatingBarChangeListener(new OnRatingBarChangeListener() { public void onRatingChanged(RatingBar ratingBar, float rating, boolean fromUser) { // do work } }); This looks more like Functional programming to me. It's a nice pattern but how is it possible to pass a method like this? In the old days a class was a class, and once compiled there was little you could do to it. My questions are: Can anyone let me know what this pattern is called? How can I write a class that can be instantiated in this way. Are there any other useful examples of functional patterns that have made their way into Java? What do I need to Google to read more about this? Thanks.

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