multiple-inheritance

There are two base classes have same function name. I want to inherit both of them, and over ride each method differently. How can I do that with separate declaration and definition (instead of defining in the class definition)? #include <cstdio> class Interface1{ public: virtual void Name() = 0; }; class Interface2 { public: virtual void Name() = 0; }; class RealClass: public Interface1, public Interface2 { public: virtual void Interface1::Name() { printf("Interface1 OK?\n"); } virtual void Interface2::Name() { printf("Interface2 OK?\n"); } }; int main() { Interface1 *p = new RealClass(); p-

Can an interface extend multiple interfaces in Java? This code appears valid in my IDE and it does compile: interface Foo extends Runnable, Set, Comparator<String> { } but I had heard that multiple inheritance was not allowed in Java. Why does there appear to be an exception for interfaces? Suresh Atta Yes, you can do it. An interface can extend multiple interfaces, as shown here: interface Maininterface extends inter1, inter2, inter3 { // methods } A single class can also implement multiple interfaces. What if two interfaces have a method defining the same name and signature? There is a

Assume I have a class implementing two or more COM interfaces: class CMyClass : public IInterface1, public IInterface2 { }; Almost every document I saw suggests that when I implement QueryInterface() for IUnknown I explicitly upcast this pointer to one of the interfaces: if( iid == __uuidof( IUnknown ) ) { *ppv = static_cast<IInterface1>( this ); //call Addref(), return S_OK } The question is why can't I just copy this ? if( iid == __uuidof( IUnknown ) ) { *ppv = this; //call Addref(), return S_OK } The documents usually say that if I do the latter I will violate the requirement that any call

http://en.wikipedia.org/wiki/Diamond_problem I know what it means, but what steps can I take to avoid it? A practical example: class A {}; class B : public A {}; class C : public A {}; class D : public B, public C {}; Notice how class D inherits from both B & C. But both B & C inherit from A. That will result in 2 copies of the class A being included in the vtable. To solve this, we need virtual inheritance. It's class A that needs to be virtually inherited. So, this will fix the issue: class A {}; class B : virtual public A {}; class C : virtual public A {}; class D : public B, public C {};