multiple-inheritance

I know the memory layout of multiple inheritance is not defined, so I should not rely on it. However, can I rely on it in a special case. That is, a class has only one "real" super class. All others are "empty classes", i.e., classes that neither have fields nor virtual methods (i.e. they only have non-virtual methods). In this case, these additional classes should not add anything to the memory layout of the class. (More concisely, in the C++11 wording, the class has standard-layout ) Can I infer that all the superclasses will have no offset? E.g.: #include <iostream> class X{ int a; int b; }

in the following code: class A { public: int x; A(int x):x(x){} }; class B: public virtual A { public: B(int x):A(x){} }; class C: public virtual A { public: C(int x):A(x){} }; class D: public B, public C { public: D(int x):B(x++), C(x++), A(x++){} }; two questions: Why do I need to add A(...) in D's initializer list? D(int x):B(x++), C(x++), A(x++){} and D(int x):A(x++), B(x++), C(x++){} both give the same result with cout<<D(10).x , why? Why do I need to add A(...) in D's initializer list? That's because virtual base subobjects must be initialized before all other subobjects. Since A does

Do interfaces solve the deadly diamond of death problem? I don't think so, for example: // A class implementing two interfaces Interface1 and Interface2. // Interface1 has int x=10 and Interface2 has int x = 20 public class MultipleInterface implements Interface1, Interface2{ public void getX(){ System.out.println(x); } } Here we get an ambiguous x . Though interfaces are a good way for solving method ambiguity, I guess they fail in the case of variables? Am I correct? If I am missing something, enlighten me. Rizwan Java resists the multiple Concrete/abstract class inheritance but not multiple

I have a class ( MyClass ) that inherits most of its functionality from a Qt built-in object ( QGraphicsTextItem ). QGraphicsTextItem inherits indirectly from QObject . MyClass also implements an interface, MyInterface . class MyClass : public QGraphicsTextItem, public MyInterface I need to be able to use connect and disconnect on MyInterface* . But it appears that connect and disconnect only work on QObject* instances. Since Qt does not support multiple inheritance from QObject-derived classes, I cannot derive MyInterface from QObject . (Nor would that make much sense for an interface anyway.

What I read in the C++ standard about injected class names contradicts (as I see it) with the behavior of a sample program I will present shortly. Here's what I read: From 3.4 (paragraph 3) The injected-class-name of a class (clause 9) is also considered to be a member of that class for the purposes of name hiding and lookup. From 9 (paragraph 2) A class-name is inserted into the scope in which it is declared immediately after the class-name is seen. The class-name is also inserted into the scope of the class itself; this is known as the injected-class-name. For purposes of access checking,