boost::shared_ptr circular dependency

c++, include, shared-ptr, tree

Solution

Because I use boost::shared_ptr I cannot use forward declaration in B.hhp

This is not true. Declaring a `shared_ptr<>` should not require the pointed type to be complete:

#include <boost/shared_ptr.hpp>

class A;

int main()
{
    boost::shared_ptr<A> pA; // OK
}

class A { };

Your problem is not with mutual dependency on header files. You definitely can use forward-declarations to break those dependency.

The problem you are having is circular referencing between objects that keep each other alive. To break this cycle, use `boost::weak_ptr`.

Also, C++11 introduces the standard class templates `std::shared_ptr` and `std::weak_ptr` (defined in the `<memory>` header), so unless you're working with C++03, you should consider using these class templates instead of Boost's ones.

//A.hpp
class A
{
    List<boost::shared_ptr<B> > children;
};

//B.hpp
class B{
   boost::weak_ptr<A> parent;
};

Problem

Original source