The page “Notes on Multiple Inheritance in GCC C++ Compiler v4.0.1” is offline now, and http://web.archive.org didn’t archive it. So, I have found a copy of the text at tinydrblog which is archived at the web archive. There is full text of the original Notes, published online as part of “Doctoral Programming Language Seminar: GCC … Read more
The constructors for virtual base classes are always called from the most derived class, using any arguments it might pass in. In your case, the most derived class doesn’t specify an initializer for A, so the default constructor is used.
[*] The technical problem is that there’s no way to work out from a Base* what the offset is between the start of the Base sub-object and the start of the Derived object. In your example it appears OK, because there’s only one class in sight with a Base base, and so it appears irrelevant … Read more
When using virtual inheritance, the virtual base class’s constructor is called directly by the most derived class’s constructor. In this case, the daughter constructor directly calls the grandmother constructor. Since you didn’t explicitly call grandmother constructor in the initialization list, the default constructor will be called. To call the correct constructor, change it to: daugther(int … Read more
virtual base classes are special in that they are initialized by the most derived class and not by any intermediate base classes that inherits from the virtual base. Which of the potential multiple initializers would the correct choice for initializing the one base? If the most derived class being constructed does not list it in … Read more
You want: (Achievable with virtual inheritance) A / \ B C \ / D And not: (What happens without virtual inheritance) A A | | B C \ / D Virtual inheritance means that there will be only 1 instance of the base A class not 2. Your type D would have 2 vtable pointers … Read more
Virtual base classes, used in virtual inheritance, is a way of preventing multiple “instances” of a given class appearing in an inheritance hierarchy when using multiple inheritance. Consider the following scenario: class A { public: void Foo() {} }; class B : public A {}; class C : public A {}; class D : public … Read more