Allowing a “friend” class to access only some private members

Question

Suppose I have three C++ classes FooA, FooB and FooC.

FooA has an member function named Hello, I want to call this function in class FooB, but I don\'t

Answer 1

You'll need inheritance. Try this:

// _ClassA.h
class _ClassA
{
  friend class ClassA;
private:
  //all your private methods here, accessible only from ClassA and _ClassA.
}

// ClassA.h
class ClassA: _ClassA
{
  friend class ClassB;
private:
  //all_your_methods
}

This way you have: ClassB is the only one to be able to use ClassA. ClassB cannot access _ClassA methods, that are private.