Is there a boost or STL class that can wrap a member pointer if it was an member variable?

I have two classes with a circular dependency problem:

• A has a member variable of class B
• B is a subclass of vector<A>

I originally solved this like this:

A.h:

#include "B.h"

class A
{
  B b;
}

B.h:

class A;

class B : public vector<A>
{
}

#include "A.h"

Unfortunately, if A and B are exported on Windows, MSVC chokes on not having a full defini开发者_开发知识库tion of A when constructing B.

To resolve this I need to store a pointer to B in A. I'd like a wrapper for this, something like boost::scoped_ptr, but that creates a new object in its constructor, and has the same copy semantics as the object it points to. This would take the form:

A.h:

class B;

class A
{
  magic_ptr<B> b;
}

B.h:

#include "A.h"

class B : public vector<A>
{
}

Before I go reinventing the wheel, does anyone know if this already exists in STL or boost?

Is boost::shared_ptr what you try to find?