inheritance

Extending class template

How would I do to extend a template class, for example vector? The below code does not work. The compiler whines about 'Vector' not being a template. template <typename T> class Vector<T> : public std::vector<T> { public: void DoSomething() { // ... } }; ...

How do I implement multiple kinds of an object in OOP?

I have multiple kinds of an object, say Car for example. Do I have each kind in an inherited class/subclass of Car? Do I place these under a cartype namespace so as not to mess up the main namespace? Then later when I need an array of cars, should I declare it as var currentCars():Car or var currentCars():Object? Would the former supp...

Using member variables inherited from a templated base class (C++)

I'm trying to use member variables of a templated base class in a derived class, as in this example: template <class dtype> struct A { int x; }; template <class dtype> struct B : public A<dtype> { void test() { int id1 = this->x; // always works int id2 = A<dtype>::x; // always works int id3 = B::...

Refactoring a C# derived class with method dependancies

Hi Folks, I want to get your opinion on this. I have a class which is derived from a base class. I don't have control over the code in the base class and it is critical to the system that I derive from it. In my class I inherite two methods that are critical to the system and are used in pretty much every function, many times. I inte...

Form Inheritance in Visual Studios designer implementations

I'm in the process of Moving a project from Visual Studio 2003 to 2005 and have just seen the The event Click is read-only and cannot be changed when using inherited forms regardless of the Modifier on the Base Forms Controls will make all the Controls from the Base Readonly in the designer (Though in 2003 it didn't work this way)...

Inherit from Type class of .Net

Is there any point at all on inheriting from Type class in .Net? i.e. What could be the meaning of doing so? I am asking this because of this text in MSDN documentation: Notes to Inheritors When you inherit from Type, you must override the following members... list of members. MSDN doc for Type: http://msdn.microsoft.com/en-u...

Exporting non-public type through public API

What if I have few factory methods returning non-public type and pairing set of methods which gives variables of this non-public type? This results with titled warning message in NetBeans. In result public API will contain only two pairing sets of methods. The reason is to make my type hierarchy sealed (like seald classes in Scala) and ...

Why aren't Java's generics implicitly polymorphic?

I'm a bit confused about how Java generics handle inheritance / polymorphism. Assume the following hierarchy - Animal (Parent) Dog - Cat (Children) So suppose I have a method doSomething(List<Animal> animals). By all the rules of inheritance and polymorphism, I would assume that a List<Dog> is a List<Animal> and a List<Cat> is a List...

XSLT: Is there a way to "inherit" canned functionality?

i am once again having to cobble together a bit of XSLT into order to turn generated XML into (rather than simply generating HTML). i'm having huge deja-vu this time again. i'm once again having to solve again basic problems, e.g.: how to convert characters into valid html entity references how to preserve whitespace/carriage returns...

C++ LNK2019 error with constructors and destructors in derived classes

I have two classes, one inherited from the other. When I compile, I get the following errors: Entity.obj : error LNK2019: unresolved external symbol "public: __thiscall Utility::Parsables::Base::Base(void)" (??0Base@Parsables@Utility@@QAE@XZ) referenced in function "public: __thiscall Utility::Parsables::Entity::Entity(void)" (??0Ent...

C++ parent class alignment

hello. Is it possible to specify alignment of parent class? for example something like (which does not compiled): template<size_t n> class Vector : public boost::array<double,n> __attribute__ ((aligned(16))) { thanks well, from comments I gather this is no good way to go. I think I will just stick to composition/alignment of private...

Inherit static properties in subclass without redeclaration?

Hi, I'm having the same problem as this guy with the application I'm writing right now. The problem is that static properties are not being inherited in subclasses, and so if I use the static:: keyword in my main class, it sets the variable in my main class as well. It works if I redeclare the static variables in my subclass, but I expe...

Help with these warnings. [inheritance].

Hello there. I have a set of code, which mimics a basic library cataloging system. There is a base class named items, in which the the general id,title and year variables are defined and 3 other derived classes (DVD,Book and CD). Base [Items] Derived [DVD,Book,CD]. The programs runs, however I get the following warnings, I'm not sure ...

C# BinarySearch breaks when inheriting from something that implements IComparable<T>?

In .NET the BinarySearch algorithm (in Lists, Arrays, etc.) appears to fail if the items you are trying to search inherit from an IComparable instead of implementing it directly: List<B> foo = new List<B>(); // B inherits from A, which implements IComparable<A> foo.Add(new B()); foo.BinarySearch(new B()); // InvalidOperationException,...

A general question about inheritence in the .NET framework

I have a general question about inheritance in the .NET framework, lets say you have 2 classes, the first is called Parent and the second is called Child. Child inherits from Parent. Parent wants to ensure that each instance of child executes a specific piece of code when it loads irrespective of whether the child has their own onLoad c...

Imitating Multiple Inheritance in PHP

I am working on my own MVC framework and found myself stuck. I need the following construction: Controller --> Backend_Controller --> Backend_Crud_Controller --> Frontend_Controller --> Frontend_Crud_Controller Both 'Backend_Crud_Controller' and 'Frontend_Crud_Controller' have the same functionali...

WPF Extended TextBox design question

Hi ! I want to derive from System.Windows.Controls.TextBox and provide this functionality. IsEnabledProperty.OverrideMetadata(typeof(MyTextBox), new FrameworkPropertyMetadata( new PropertyChangedCallback(delegate(DependencyObject o, DependencyPropertyChangedEventArgs e) { MyTextBox tb = o as MyTe...

Force calling the derived class implementation within a generic function in C#?

Ok so I'm currently working with a set of classes that I don't have control over in some pretty generic functions using these objects. Instead of writing literally tens of functions that essentially do the same thing for each class I decided to use a generic function instead. Now the classes I'm dealing with are a little weird in that t...

ASP.NET MVC 2.0: Using Partial Classing or Inheritance on Database/Object Model?

I ask this because i'm using Partial classing to extend my db model, and in doing so some snags i've run into using inheritance and also snags i've run into declaring my db model in another class as a property and just using it like that ie: Public Property DBModelClass as DBModelClassType - however, doign direct partial classing has wo...

Friendness and derived class

Hi, Let's say I have the following class hierarchy: class Base { protected: virtual void foo() = 0; friend class Other; }; class Derived : public Base { protected: void foo() { /* Some implementation */ }; }; class Other { public: void bar() { Derived* a = new Derived(); a->foo(); // Compile...