Problem with cyclic dependency

[soup007]

Hi,
I am having some difficulties with cyclic dependency between two classes. Situation is something like following -

///A.h
#include "B.h"
 
class A {
{
   int X;
public:
   P() { Q(); }
   Q() {
      R();
      bb = new B();
      bb.D( this ); )
   R() { uses X )
 
};
 
///B.h
class B: public someclass {
public:
   D(A& a) {
      a.Q();        //end condition for recursion depends on X 
      a.R();
 
};

SOME BACKGROUND-
I couldn't create D() in A as D() access private data in B. But D() calls
both Q() and R() and value of X has to be same everywhere. i.e. R()
called from D access the same X value that was used by class A. That's why I am passing this pointer of class A to B. There will be just one instance of A and B. But there isn't just one class B, there are lots of classes like B derived from a parent class. I am actually creating objects for these classes, kind of linked list. A has functions for creating a list, but it may be nested that's why there is a recursion.

PROBLEM-
Forward declaration of A in B doesn't work and I can't include header of A to B as header of B is included in A. I am using kdevelop on suse.
How do I solve this thing? Sorry for such a long description.
Any help would be very appreciated. Thanks.

[Savage]

You cannot use forward declaration because you need to access class methods, and by giving it only a forward declaration there is no way for compiler to know which are the methods and members of the forward declared class.
Instead try declaring a interface for class A in B.h which will contain Q() and R(). That interface will be passed as reference to D in class B.In A.h you will derive class A from this interface and trough polymorphism you should be able to get this to work.

Savage

[soup007]

You cannot use forward declaration because you need to access class methods, and by giving it only a forward declaration there is no way for compiler to know which are the methods and members of the forward declared class.
Instead try declaring a interface for class A in B.h which will contain Q() and R(). That interface will be passed as reference to D in class B.In A.h you will derive class A from this interface and trough polymorphism you should be able to get this to work.

Savage

Thanks a lot for the reply, I will just try that.

[soup007]

Beautiful, works like a charm.
Thanks