How to add handle as a class member, where class is used for template of heap?

Question

Consider the simple example:

#include <boost/heap/fibonacci_heap.hpp>

class MyClass;

struct compare_distances
{
    bool operator()(const MyClass* n1, const MyClass* n2) const
    {
        return n1->distance > n2->distance;
    }
};

typedef boost::heap::fibonacci_heap<MyClass*, boost::heap::compare<compare_distances> > fib_heap;

class MyClass
{
    public:
        string name;
        double distance;
        fib_heap::handle_type handle;
};

I want to have the access to handle of object of MyClass at heap in this manner. So I forward declare MyClass. But compiler says: error: invalid use of incomplete type ‘const class MyClass’ (error for return line in compare_distances). How to fix it?

It is necessary to implement a convenient network of objects such as:

class MyClass
{
    public:
        string name;
        double distance;
        fib_heap::handle_type handle[4]; // handles for other objects of MyClass
};

Answer 1

This compiles if you just declare the comparator functor's operator() before MyClass and you define it after the class definition like this:

class MyClass;

struct compare_distances
{
    inline bool operator()(const MyClass* n1, const MyClass* n2) const;
};

typedef boost::heap::fibonacci_heap<MyClass*, boost::heap::compare<compare_distances> > fib_heap;

class MyClass
{
public:
    string name;
    double distance;
    fib_heap::handle_type handle;
};

bool compare_distances::operator()(const MyClass* n1, const MyClass* n2) const
{
    return n1->distance > n2->distance;
}

Note that I've added inline to the function to avoid linker errors. (Member functions defined in a struct are implicitly inline.)