Re: Double abstract class Inheritance concern.

[Nathan Sidwell <nathan@xxxxxxxxxxxxxxxx>]

Tiago Stein wrote:
> > Chris Lattner wrote:
> >
> > > Tiago Stein wrote:
> > >
> > >
> > > > class A{};
> > > > class B :public A{};
> > > > class C: public A{ int g; };
> > > > class D: public B, public C {
> > > > unsigned int foo;
> > > > };
> > > > Why sizeof class D is 12? Should not be 8?

> But is not only a single A present at D?
no, there are two.

> If I wanted separate A for each
> side of inheritance shouldn't I use virtual inheritance?
no you'd use that when you wanted one instance

> When I Use it..
> it adds even more size to the final class, so that I have more space used
> than is necessary to keep each onde witha separet adress.
yes, that is what the standard says.

> So if I understand correctly.. yhis is done to keep B and A with different
> addresses.. and not B::A and C::A ?
you do not understand correctly.

this is now no longer a g++ specific question, but one about C++. A C++
newsgroup would be appropriate to explore the whys of this requirement.

nathan

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