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  • Needing forward declaration in Ruby

    - by dbarbosa
    Hi, I am trying to write a Ruby script in one file. I would like to know if it is possible to write the "main" function in the beginning, having the other functions that are used by main, defined after it. In other words, I would like to call a not yet defined function, so that they do not depends on definition order. Just changing the order is not possible because it gives an "undefined method" error. In C/C++ we use forward declarations... is there something similar in Ruby or another solution to this?

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  • java looping - declaration of a Class outside / inside the loop

    - by lisak
    when looping, for instance: for ( int j = 0; j < 1000; j++) {}; and I need to instantiate 1000 objects, how does it differ when I declare the object inside the loop from declaring it outside the loop ?? for ( int j = 0; j < 1000; j++) {Object obj; obj =} vs Object obj; for ( int j = 0; j < 1000; j++) {obj =} It's obvious that the object is accessible either only from the loop scope or from the scope that is surrounding it. But I don't understand the performance question, garbage collection etc. What is the best practice ? Thank you

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  • Declaration, allocation and assignment of an array of pointers to function pointers

    - by manneorama
    Hello Stack Overflow! This is my first post, so please be gentle. I've been playing around with C from time to time in the past. Now I've gotten to the point where I've started a real project (a 2D graphics engine using SDL, but that's irrelevant for the question), to be able to say that I have some real C experience. Yesterday, while working on the event system, I ran into a problem which I couldn't solve. There's this typedef, //the void parameter is really an SDL_Event*. //but that is irrelevant for this question. typedef void (*event_callback)(void); which specifies the signature of a function to be called on engine events. I want to be able to support multiple event_callbacks, so an array of these callbacks would be an idea, but do not want to limit the amount of callbacks, so I need some sort of dynamic allocation. This is where the problem arose. My first attempt went like this: //initial size of callback vector static const int initial_vecsize = 32; //our event callback vector static event_callback* vec = 0; //size static unsigned int vecsize = 0; void register_event_callback(event_callback func) { if (!vec) __engine_allocate_vec(vec); vec[vecsize++] = func; //error here! } static void __engine_allocate_vec(engine_callback* vec) { vec = (engine_callback*) malloc(sizeof(engine_callback*) * initial_vecsize); } First of all, I have omitted some error checking as well as the code that reallocates the callback vector when the number of callbacks exceed the vector size. However, when I run this code, the program crashes as described in the code. I'm guessing segmentation fault but I can't be sure since no output is given. I'm also guessing that the error comes from a somewhat flawed understanding on how to declare and allocate an array of pointers to function pointers. Please Stack Overflow, guide me.

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  • What would be different in Java if Enum declaration didn't have the recursive part

    - by atamur
    Please see http://stackoverflow.com/questions/211143/java-enum-definition and http://stackoverflow.com/questions/3061759/why-in-java-enum-is-declared-as-enume-extends-enume for general discussion. Here I would like to learn what exactly would be broken (not typesafe anymore, or requiring additional casts etc) if Enum class was defined as public class Enum<E extends Enum> I'm using this code for testing my ideas: interface MyComparable<T> { int myCompare(T o); } class MyEnum<E extends MyEnum> implements MyComparable<E> { public int myCompare(E o) { return -1; } } class FirstEnum extends MyEnum<FirstEnum> {} class SecondEnum extends MyEnum<SecondEnum> {} With it I wasn't able to find any benefits in this exact case. PS. the fact that I'm not allowed to do class ThirdEnum extends MyEnum<SecondEnum> {} when MyEnum is defined with recursion is a) not relevant, because with real enums you are not allowed to do that just because you can't extend enum yourself b) not true - pls try it in a compiler and see that it in fact is able to compile w/o any errors PPS. I'm more and more inclined to believe that the correct answer here would be "nothing would change if you remove the recursive part" - but I just can't believe that.

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  • Using 'or' in Java Generics declaration

    - by Shervin
    I have a method that returns an instance of Map<String, List<Foo>> x(); and another method that returns an instance of Map<String, Collection<Foo>> y(); Now if I want to dynamically add one of this Maps in my field, how can I write the generics for it to work? ie: public class Bar { private Map<String, ? extends Collection<Foo>> myMap; public void initializer() { if(notImportant) myMap = x(); //OK else myMap = y(); // !OK (Need cast to (Map<String, ? extends Collection<Foo>>) } Now is it ok that I cast to the signature even though the y() is declared as being Collection? } } If it is not ok to cast, can I somehow write this (Collection OR List) I mean, List is a Collection, so it should somehow be possible. private Map<String, Collection<Foo> | List<Foo>>> myMap;

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  • Javascript Namespace Declaration

    - by objektivs
    What neat ways do you use for declaring JavaScript namespaces. I've come across this one: if (Foo == null || typeof(Foo) != "object") { var Foo = new Object();} Is there a more elegant or succinct way of doing this? Just a bit of fun...

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  • storing an integral value in a pointer variable while declaration

    - by benjamin button
    int main() { int *d=0; printf("%d\n",*d); return 0; } this works fine. >cc legal.c > ./a.out 0 if i change the statement int *d=0; to int *d=1; i see the error. cc: "legal.c", line 6: error 1522: Cannot initialize a pointer with an integer constant other than zero. so its obvious that it will allow only zero.i want to know what happens inside the memory when we do this int *d=0 which is making it valid syntax. I am just asking this out of curiosity!

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  • Jump to function declaration in php

    - by aeonsleo
    HI, I have the following ide's for php Dreamweaver php-Eclipse Textpad I wish to jump to a function's definition which is located in another file which is not yet open. How could I do that. I am studying a websites code and have the entire directory struction in my local root folder. I come accross certain functions and I dont know in which file their definition is. Pls suggest something.Thanks

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  • Jsp declaration element

    - by Stardust
    <%! class father { static int s = 0; } %> <% father f1 = new father(); father f2 = new father(); f1.s++; out.println(f2.s); // It must print "1" %> When I run the file, I got this error. Can anybody explain? "The field s cannot be declared static; static fields can only be declared in static or top level types"

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  • JavaScript Namespace Declaration

    - by Hery
    I created a javascript class as follow: var MyClass = (function() { function myprivate(param) { console.log(param); } return { MyPublic : function(param) { myprivate(param); } }; })(); MyClass.MyPublic("hello"); The code above is working, but my question is, how if I want to introduce namespace to that class. Basically I want to be able to call the class like this: Namespace.MyClass.MyPublic("Hello World"); If I added Namespace.MyClass, it'll throw error "Syntax Error". I did try to add "window.Namespace = {}" and it doesn't work either. Thanks.. :)

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  • typedef declaration syntax

    - by mt_serg
    Some days ago I looked at boost sources and found interesting typedef. There is a code from "boost\detail\none_t.hpp": namespace boost { namespace detail { struct none_helper{}; typedef int none_helper::*none_t ; } // namespace detail } // namespace boost I didn't see syntax like that earlier and can't explain the sense of that. This typedef introduces name "none_t" as pointer to int in boost::detail namespace. What the syntax is? And what difference between "typedef int none_helper::*none_t" and for example "typedef int *none_t" ?

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  • Calling a jQuery method at declaration time, and then onEvent

    - by cesarsalazar
    I've been writing JS (mainly jQuery) for quite a few months now, but today I decided to make my first abstraction as a jQuery method. I already have working code but I feel/know that I'm not doing it the right way, so I come here for some enlightenment. Note: Please do not reply that there's already something out there that does the trick as I already know that. My interest in this matter is rather educational. What my code is intended to do (and does): Limit the characters of a textfield and change the color of the counter when the user is approaching the end. And here's what I have: $(function(){ $('#bio textarea').keyup(function(){ $(this).char_length_validation({ maxlength: 500, warning: 50, validationSelector: '#bio .note' }) }) $('#bio textarea').trigger('keyup'); }) jQuery.fn.char_length_validation = function(opts){ chars_left = opts.maxlength - this.val().length; if(chars_left >= 0){ $(opts.validationSelector + ' .value').text(chars_left); if(chars_left < opts.warning){ $(opts.validationSelector).addClass('invalid'); } else{ $(opts.validationSelector).removeClass('invalid'); } } else{ this.value = this.value.substring(0, opts.maxlength); } } In the HTML: <div id="bio"> <textarea>Some text</textarea> <p class="note> <span class="value">XX</span> <span> characters left</span> </p> </div> Particularly I feel really uncomfortable binding the event each on each keyup instead of binding once and calling a method later. Also, (and hence the title) I need to call the method initially (when the page renders) and then every time the user inputs a character. Thanks in advance for your time :)

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  • Java Method declaration

    - by user1701604
    I'm trying to declare a method for my program that takes only a 5 digit integer and for each digit of the integer, reads a value from the program and prints it out. I understand this isn't very clear but im having trouble relaying what I mean. I understand it will be some sort of for loop to read each digit of the integer individually until something reaches 5. Something like the charAt() string method but works for digits.

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  • friend declaration block an external function access to the private section of a class

    - by MiP
    I'm trying to force function caller from a specific class. For example this code bellow demonstrate my problem. I want to make 'use' function would be called only from class A. I'm using a global namespace all over the project. a.h #include "b.h" namespace GLOBAL{ class A{ public: void doSomething(B); } } a.cpp #include "a.h" using namespace GLOBAL; void A::doSomething(B b){ b.use(); } b.h namespace GLOBAL{ class B{ public: friend void GLOBAL::A::doSomething(B); private: void use(); } Compiler says: ‘GLOBAL::A’ has not been declared ‘void GLOBAL::B::use()’ is private Can anyone help here ? Thanks a lot, Mike.

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  • Confusing Javascript class declaration

    - by clutch
    I have some third-party Javascript that has statements like this: FOO = function() { ...functions() ... return { hash } }(); It is working as designed but I'm confused by it. Can anybody define what this structure is doing? Is it just a weird way to create a class?

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  • A general declaration for all inherited classes

    - by Soham
    Consider, there is a class called SuperClass from which, ClassA, ClassB, ClassC is derived. From each one of those derived Classes, there are further more two classes are derived each called ChildClassAA and ChildClassAB[AB stands for Bth Child class from the Ath Class.Lets not really pull our hair on this nomenclature]. Now, ideally, I want to declare a general type as a private member of another Class say IndependentClass which can be initialized during run time as either of the objects of type ClassAor ClassB or ClassC and even the derived classes like ClassAA or ClassAB. Is there a possible way to do it?

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  • Allowed characters in linux environment variable names

    - by Christian Semrau
    What characters are allowed in linux environment variable names? My cursory search of man pages and the web did only produce information about how to work with variables, but not which names are allowed. I have a Java program that requires an defined environment variable containing a dot, like com.example.fancyproperty. With Windows I can set that variable, but I had no luck setting it in linux (tried in SuSE and Ubuntu). Is that variable name even allowed?

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  • Java compiler rejects variable declaration with parameterized inner class

    - by Johansensen
    I have some Groovy code which works fine in the Groovy bytecode compiler, but the Java stub generated by it causes an error in the Java compiler. I think this is probably yet another bug in the Groovy stub generator, but I really can't figure out why the Java compiler doesn't like the generated code. Here's a truncated version of the generated Java class (please excuse the ugly formatting): @groovy.util.logging.Log4j() public abstract class AbstractProcessingQueue <T> extends nz.ac.auckland.digitizer.AbstractAgent implements groovy.lang.GroovyObject { protected int retryFrequency; protected java.util.Queue<nz.ac.auckland.digitizer.AbstractProcessingQueue.ProcessingQueueMember<T>> items; public AbstractProcessingQueue (int processFrequency, int timeout, int retryFrequency) { super ((int)0, (int)0); } private enum ProcessState implements groovy.lang.GroovyObject { NEW, FAILED, FINISHED; } private class ProcessingQueueMember<E> extends java.lang.Object implements groovy.lang.GroovyObject { public ProcessingQueueMember (E object) {} } } The offending line in the generated code is this: protected java.util.Queue<nz.ac.auckland.digitizer.AbstractProcessingQueue.ProcessingQueueMember<T>> items; which produces the following compile error: [ERROR] C:\Documents and Settings\Administrator\digitizer\target\generated-sources\groovy-stubs\main\nz\ac\auckland\digitizer\AbstractProcessingQueue.java:[14,96] error: improperly formed type, type arguments given on a raw type The column index of 96 in the compile error points to the <T> parameterization of the ProcessingQueueMember type. But ProcessingQueueMember is not a raw type as the compiler claims, it is a generic type: private class ProcessingQueueMember <E> extends java.lang.Object implements groovy.lang.GroovyObject { ... I am very confused as to why the compiler thinks that the type Queue<ProcessingQueueMember<T>> is invalid. The Groovy source compiles fine, and the generated Java code looks perfectly correct to me too. What am I missing here? Is it something to do with the fact that the type in question is a nested class? (in case anyone is interested, I have filed this bug report relating to the issue in this question) Edit: Turns out this was indeed a stub compiler bug- this issue is now fixed in 1.8.9, 2.0.4 and 2.1, so if you're still having this issue just upgrade to one of those versions. :)

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  • implicit declaration of function 'objc_lookUpClass'

    - by idober
    I am getting this warning for the line code: Class myClass = objc_lookUpClass([_className UTF8String]); I am adding #import <Foundation/NSObjCRuntime.h> #import <objc/objc.h> And it still don't resolve the problem Another warning i get on this line is: "Initialization makes pointer from integer without a cast"

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  • I changed the web service declaration and then wsimport says that I have a repeated message

    - by Oso
    I had a Web service method working fine on Tomcat as deployed by Netbeans 6.8. Then I had to add a new parameter for the same method so I erased the method and then added a new one with the same name but different parameters. After that, ws-import keeps on telling me that I have duplicated messages for such method, and if I remove the new one, the WSDL will still show me the old one with the old parameter list. How do I get rid of the old one? thanks in advance.

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  • ANTLR C grammar, optional init_declarator_list?

    - by eisbaw
    Hello, In the ANSI C grammar for ANTLR v3 ( http://antlr.org/grammar/1153358328744/C.g ), how can init_declarator_list be optional in rule declaration ? Instead of: | declaration_specifiers init_declarator_list? ';' -I would say: | declaration_specifiers init_declarator_list ';' What part of the C standard allows statements like: int; EDIT: I just tried, it is allowed! Okay then, why is it allowed?

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  • jquery document.ready multiple declaration

    - by Hendry H.
    I realized that I can specify $(document).ready(function(){}); more than once. Suppose like this $(document).ready(function(){ var abc = "1122"; //do something.. }); $(document).ready(function(){ var abc = "def"; //do something.. }); Is this standard ? Those codes work on my FF (16.0.2). I just a little afraid that other browser may not. What actually happen ? How jQuery handle those code ? Thanks.

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