CGAL: Inheritance and the kernel

Question

CGAL question:

Im trying the add one property to the point class. The first step I guess is to inherit a kernel and replace the point class with my own which I inherit from CGAL's. But just trying to get this small first step I run into trouble.

Edit: Based on the comment below I changed the inheritance to the way it's described in the Manual. The code below gives the following compile error:

• ‘typename CGAL::Extended_homogeneous::Base’ names 'CGAL::Extended_homogeneous::Base’, which is not a class template|

among others.

MyBase.h

#include <CGAL/Extended_homogeneous.h>

template < typename K_, typename K_Base >
class My_base  : public K_Base::template Base<K_>::Type
{
  typedef typename K_Base::template Base<K_>::Type   OldK;

public:
  typedef K_                                Kernel;

  template < typename Kernel2 >
  struct Base { typedef My_base<Kernel2, K_Base>  Type; };
 };

template < typename RT_ >
struct MyKernel  : public CGAL::Type_equality_wrapper<My_base<MyKernel<RT_>, CGAL::Homogeneous<RT_> >,  MyKernel<RT_> >
{};

Minimal.cpp

#include "MyKernel.h"
#include <CGAL/Nef_polyhedron_3.h>
typedef MyKernel<CGAL::Gmpz>    Kernel;

typedef CGAL::Nef_polyhedron_3<Kernel>  Nef_Polyhedron;
typedef Nef_Polyhedron::Plane_3  Plane;

int main()
{
  Nef_Polyhedron half_space(Plane(1,1,1,1), Nef_Polyhedron::EXCLUDED);

  return 0;
}

If the inhertiance is changed to "public K_Base::Base::template B::Type" it will compile but Then I miss the propeties from the Extentensions I guess? Because I get the error

• "Constructor not available for this kernel"

  when I run the program

Answer 1

The correct way to define your own kernel is described on the following page.

The things look complicated because of the type equality wrapper which makes Kernel::Point_2 equal to Point_2.