How to solve Boost::BGL template<->class circular dependency?

Question

I have a problem with using the adjacency-list of the Boost Graphics Library. It seems to be a circular dependency problem: I have a typedef T of a template which uses some class A. Additionally A stores a pointer to an object of type T. Now the compiler tells me, that T does not name a type.

Here are excerptions of my more concrete files:

//graphdefinitions.hpp
#include "lane.hpp"
#include "tie.hpp"

typedef boost::adjacency_list<boost::listS, boost::listS, 
                              boost::directedS, Tie, Lane> Map;
typedef boost::graph_traits<Map>::edge_descriptor edge_descriptor;

//lane.hpp
#include "graphdefinitions.hpp"
class Lane {
    ...
    edge_descriptor *left, *right;
};

//tie.hpp
//no important includes here
class Tie {
    ...
};

How do I solve this dependency / inclusion-order problem?

ANOTHER EDIT: I just had the idea that the type of an edge_descriptor might be a primitive one like int. That would have solved the problem because I would have been able to replace the edge_descriptors of Lane by plain int-variables and thus could have removed the inclusion of graphdefinitions.hpp inside tie.hpp. Unfortunately my idea was cra* and I have to find another solution. Edge_descriptor types seem to be there for a reason...

Answer 1

You have circularly included headers. Lane includes graphdefinitions, which includes lane, which includes graphdefinitions, etc. This is the cause of your problem.

Edit: I realized this was already mentioned in the OP. The solution to this problem is PIMPL.

Edit: What I would actually do is put the typedef inside the Lane class. That should solve the problem in the neatest way.