Re: forward declaration of class from another namespace

1. I got header "headerA.h" with the following code:

----------------------------------------
#include "headerB.h"

namespace A
{
       class A
       {
            public:

               create_b_ojects()
               {
                    B* pB = new B( this );
               }
       };
}

-------------------------------------

2. And I got header "headerB.h" with the following code:
-------------------------------------------
namespace B
{

     class B
     {
           public:
             B(){}
             B( /* here I need to use pointer to object of type A::A
*/ ){....}
     };

}
-------------------------------------------
Question:
what is the correct way to make forward declaration of class A::A in
module B?