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  • C++ non-member functions for nested template classes

    - by beldaz
    I have been writing several class templates that contain nested iterator classes, for which an equality comparison is required. As I believe is fairly typical, the comparison is performed with a non-member (and non-friend) operator== function. In doing so, my compiler (I'm using Mingw32 GCC 4.4 with flags -O3 -g -Wall) fails to find the function and I have run out of possible reasons. In the rather large block of code below there are three classes: a Base class, a Composed class that holds a Base object, and a Nested class identical to the Composed class except that it is nested within an Outer class. Non-member operator== functions are supplied for each. These classes are in templated and untemplated forms (in their own respective namespaces), with the latter equivalent to the former specialised for unsigned integers. In main, two identical objects for each class are compared. For the untemplated case there is no problem, but for the templated case the compiler fails to find operator==. What's going on? #include <iostream> namespace templated { template<typename T> class Base { T t_; public: explicit Base(const T& t) : t_(t) {} bool equal(const Base& x) const { return x.t_==t_; } }; template<typename T> bool operator==(const Base<T> &x, const Base<T> &y) { return x.equal(y); } template<typename T> class Composed { typedef Base<T> Base_; Base_ base_; public: explicit Composed(const T& t) : base_(t) {} bool equal(const Composed& x) const {return x.base_==base_;} }; template<typename T> bool operator==(const Composed<T> &x, const Composed<T> &y) { return x.equal(y); } template<typename T> class Outer { public: class Nested { typedef Base<T> Base_; Base_ base_; public: explicit Nested(const T& t) : base_(t) {} bool equal(const Nested& x) const {return x.base_==base_;} }; }; template<typename T> bool operator==(const typename Outer<T>::Nested &x, const typename Outer<T>::Nested &y) { return x.equal(y); } } // namespace templated namespace untemplated { class Base { unsigned int t_; public: explicit Base(const unsigned int& t) : t_(t) {} bool equal(const Base& x) const { return x.t_==t_; } }; bool operator==(const Base &x, const Base &y) { return x.equal(y); } class Composed { typedef Base Base_; Base_ base_; public: explicit Composed(const unsigned int& t) : base_(t) {} bool equal(const Composed& x) const {return x.base_==base_;} }; bool operator==(const Composed &x, const Composed &y) { return x.equal(y); } class Outer { public: class Nested { typedef Base Base_; Base_ base_; public: explicit Nested(const unsigned int& t) : base_(t) {} bool equal(const Nested& x) const {return x.base_==base_;} }; }; bool operator==(const Outer::Nested &x, const Outer::Nested &y) { return x.equal(y); } } // namespace untemplated int main() { using std::cout; unsigned int testVal=3; { // No templates first typedef untemplated::Base Base_t; Base_t a(testVal); Base_t b(testVal); cout << "a=b=" << testVal << "\n"; cout << "a==b ? " << (a==b ? "TRUE" : "FALSE") << "\n"; typedef untemplated::Composed Composed_t; Composed_t c(testVal); Composed_t d(testVal); cout << "c=d=" << testVal << "\n"; cout << "c==d ? " << (c==d ? "TRUE" : "FALSE") << "\n"; typedef untemplated::Outer::Nested Nested_t; Nested_t e(testVal); Nested_t f(testVal); cout << "e=f=" << testVal << "\n"; cout << "e==f ? " << (e==f ? "TRUE" : "FALSE") << "\n"; } { // Now with templates typedef templated::Base<unsigned int> Base_t; Base_t a(testVal); Base_t b(testVal); cout << "a=b=" << testVal << "\n"; cout << "a==b ? " << (a==b ? "TRUE" : "FALSE") << "\n"; typedef templated::Composed<unsigned int> Composed_t; Composed_t c(testVal); Composed_t d(testVal); cout << "c=d=" << testVal << "\n"; cout << "d==c ? " << (c==d ? "TRUE" : "FALSE") << "\n"; typedef templated::Outer<unsigned int>::Nested Nested_t; Nested_t e(testVal); Nested_t f(testVal); cout << "e=f=" << testVal << "\n"; cout << "e==f ? " << (e==f ? "TRUE" : "FALSE") << "\n"; // Above line causes compiler error: // error: no match for 'operator==' in 'e == f' } cout << std::endl; return 0; }

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  • Finding unused classes in C# app.

    - by duder
    I'm a C#/.net/Visual Studio noob. I inherited a half-completed C# application for a mobile phone. In the course of debugging, I came across several half-finished classes that don't seem to be used anywhere else in the code. Is there a way to get determine if a class definition is instantiated anywhere?

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  • Documenting Objective C classes, methods and variables

    - by Alex Reynolds
    What are good approaches to documenting ObjC classes, variables and methods, esp. for automated, downstream class creation, documentation creation, and general integration with Xcode? As an example, I like to use: #pragma mark - #pragma mark UITextField delegate methods for demarcating chunks of code of interest, for quick access from within Xcode.

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  • ColdFusion CFC implementation of C# Partial Class?

    - by Brian David Berman
    Does ColdFusion offer a mechanism for splitting CFCs into multiple files? I am NOT talking about extension, I am talking about splitting the SAME CFC into multiple files; the same way C# allows for "partial" classes. The reason for this is because I am using T4 to generate a bunch of CFCs and I want to be able to tag functionality onto the generated CFC by doing so in another file. I want to do this in a way that doesn't violate the Open-Closed Principle.

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  • Use reflection to get a list of static classes

    - by Christian
    Hi, many questions are close, but none answers my problem... How do I use reflection in C# 3.5 to get all classes which are static from an assembly. I already get all Types defined, but there is no IsStatic property. Counting 0 constructors is really slow and did not work either. Any tips or a line of code? :-) Chris

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  • Combining multiple classes gives me errors

    - by Martti Laine
    Hello I'm creating a website with structure like this: class main { } class mysql extends main { } class user extends main { } class etc extends main { } The idea is for these classes to use functions from each other. This doesn't work. How can I call a function from mysql in user? Martti Laine

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  • C#: Abstract classes need to implement interfaces?

    - by bguiz
    My test code in C#: namespace DSnA { public abstract class Test : IComparable { } } Results in the following compiler error: error CS0535: 'DSnA.Test' does not implement interface member 'System.IComparable.CompareTo(object)' Since the class Test is an abstract class, why does the compiler require it to implement the interface? Shouldn't this requirement only be compulsory for concrete classes?

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  • selecting the first of multiple classes

    - by gleddy
    Not sure if you can do this, but I want to select the first of two classes of an element with jQuery and return it's first class only. <div class="module blue"> I want to return 'module'. tried this: var state = $('body').attr('class').first(); but none of that seems to work, thanks for any advice.

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  • Missing JAXB classes from XMLschema.xsd

    - by XLR
    Hi, I'm working on a xml schema resolver and I'm using JAXB with XMLSchema.xsd. I experience problems with JAXB, because I don't get classes for all the top level elements. For example for <xs:element name="maxLength" id="maxLength" type="xs:numFacet"> I do not get a class MaxLength or anything like that. Only NumFacet exists. Anyone else experienced that and could please help me? Cheers, XLR

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  • Exporting classes containing std:: objects (vector, map, etc) from a dll

    - by RnR
    I'm trying to export classes from a DLL that contain objects such as std::vectors and std::stings - the whole class is declared as dll export through: class DLL_EXPORT FontManager { The problem is that for members of the complex types I get this warning: warning C4251: 'FontManager::m__fonts' : class 'std::map<_Kty,_Ty' needs to have dll-interface to be used by clients of class 'FontManager' with [ _Kty=std::string, _Ty=tFontInfoRef ] I'm able to remove some of the warnings by putting the following forward class declaration before them even though I'm not changing the type of the member variables themselves: template class DLL_EXPORT std::allocator<tCharGlyphProviderRef>; template class DLL_EXPORT std::vector<tCharGlyphProviderRef,std::allocator<tCharGlyphProviderRef> >; std::vector<tCharGlyphProviderRef> m_glyphProviders; Looks like the forward declaration "injects" the DLL_EXPORT for when the member is compiled but is it safe? Does it realy change anything when the client compiles this header and uses the std container on his side? Will it make all future uses of such a container DLL_EXPORT (and possibly not inline?)? And does it really solve the problem that the warning tries to warn about? Is this warning anything I should be worried about or would it be best to disable it in the scope of these constructs? The clients and the dll will always be built using the same set of libraries and compilers and those are header only classes... I'm using Visual Studio 2003 with the standard STD library. ---- Update ---- I'd like to target you more though as I see the answers are general and here we're talking about std containers and types (such as std::string) - maybe the question really is: Can we disable the warning for standard containers and types available to both the client and the dll through the same library headers and treat them just as we'd treat an int or any other built-in type? (It does seem to work correctly on my side.) If so would should be the conditions under which we can do this? Or should maybe using such containers be prohibited or at least ultra care taken to make sure no assignment operators, copy constructors etc will get inlined into the dll client? In general I'd like to know if you feel designing a dll interface having such objects (and for example using them to return stuff to the client as return value types) is a good idea or not and why - I'd like to have a "high level" interface to this functionality... maybe the best solution is what Neil Butterworth suggested - creating a static library?

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  • Class accessing inner class privates?

    - by aloh
    Class Outer { ... private class Node { private T data; ... private T getData() { return data; } } } What's the purpose of using set and get methods if the outer class can access inner class private members? What's the purpose of making inner classes private? Package access?

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  • Question about factory classes

    - by devoured elysium
    Currently I have created a ABCFactory class that has a single method creating ABC objects. Now that I think of it, maybe instead of having a factory, I could just make a static method in my ABC Method. What are the pro's and con's on making this change? Will it not lead to the same? I don't foresee having other classes inherit ABC, but one never knows! Thanks

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  • How to configure Jetty to reload a WebAppContext when classes are changed

    - by Guss
    I'm developing a web application and I run Jetty as the development and testing environment when I develop under Eclipse. When I make changes to Java classes, Eclipse automatically compiles them to the build directory, but Jetty won't see the changes until I stop and start the server. I know that Jetty supports "hot deployment" using ContextDeployer that will refresh updated application contexts, but it relies on a context file in a context directory being updated - which is not very useful in my case. Is there a way to set up Jetty so that it will reload the web app when any of the classes it uses is updated? My current jetty.xml looks something like this: <?xml version="1.0"?> <!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure.dtd"> <Configure id="Server" class="org.eclipse.jetty.server.Server"> <Set name="ThreadPool"><!-- bla bla --></Set> <Call name="addConnector"><!-- bla bla --></Call> <Set name="handler"> <New id="Handlers" class="org.eclipse.jetty.server.handler.HandlerCollection"> <Set name="handlers"> <Array type="org.eclipse.jetty.server.Handler"> <Item> <New id="webapp" class="org.eclipse.jetty.webapp.WebAppContext"> <Set name="displayName">My Web App</Set> <Set name="resourceBase">src/main/webapp</Set> <Set name="descriptor">src/main/webapp/WEB-INF/web.xml</Set> <Set name="contextPath">/mywebapp</Set> </New> </Item> <Item> <New id="DefaultHandler" class="org.eclipse.jetty.server.handler.DefaultHandler"/> </Item> </Array> </Set> </New> </Set> </Configure>

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  • Grails dependency inject domain classes

    - by Don
    Hi, The Grails manual shows this example of dependency injecting domain classes: class Book { def bookService def buyBook() { bookService.buyBook(this) } } However, I tried this out, and bookService is null. My guess is that the dependency injection happens when an object is loaded from the DB, so the following will always return null new Book().bookService Can someone confirm this?

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  • Python and classes

    - by Artyom
    Hello, i have 2 classes. How i call first.TQ in Second ? Without creating object First in Second. class First: def __init__(self): self.str = "" def TQ(self): pass def main(self): T = Second(self.str) # Called here class Second(): def __init__(self): list = {u"RANDINT":first.TQ} # List of funcs maybe called in first ..... ..... return data

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