Re: About abstract classes and Inheritance

Victor Bazarov <>
Tue, 13 Oct 2009 20:00:57 -0400
Barzo wrote:

On 13 Ott, 20:45, Victor Bazarov <> wrote:

A doubt? A doubt you have when you are uncertain of some belief or
opinion, or when you lack confidence in your abilities.

You actually just have *two questions*.

Ok, I have two questions.. :-P

 > In the following code, why BaseAImpl is

abstract? Deriving it from BaseImpl the IBase::foo() is not defined?

'BaseAImpl' has two objects of type 'IBase'. One inside 'BaseImpl'
subobject, and the other inside the 'IBaseA' subobject. The former
defines the final overrider for 'IBase::foo', the latter does not.
That's why it's abstract. And, no, one base class' final overrider does
NOT become the final overrider for another base class' virtual function.

Thanks, now I understand.

I solved using 'virtual' Inheritance:

class IBase {...};

class IBaseA : virtual public IBase {...};

class BaseImpl : virtual public IBase {...};

class BaseAImpl : public IBaseA, public BaseImpl {...};

In this manner only one IBase object will be created, right?


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