TITLE: forward declaration of nested class?

(Newsgroups: comp.lang.c++.moderated, 1 Sep 98)

WOODARD: "Tim Woodard" <timwoodard@dvc400.com> writes:

> Is there any way to forward declare a nested class without
> including the definition of the parent class? For example:

> // A.h
> class A {
> public:
>    class B { };
> };
>
> // Some other file
> // I don't want to #include "A.h" just to get A::B
> class A;
> class A::B;
>
> I know that this method doesn't work, but does anything else?


CLAMAGE: clamage@Eng.Sun.COM (Steve Clamage)

No. You cannot mention a member of a class unless the class
definition is visible.

You can un-nest the inner class and put both classes in a
namespace:

namespace AB {
    class A;
    class B;
}

In some other file you can provide the definitions of A and B.
Unlike classes, namespaces can be re-opened and added to.