CGAL users discussion list

[Johannes Ulen <>]

Thank you!
With minor adjustment the code you sent did exactly what I needed. 

For my curiosity (and futher people ending up here when they search for
my problem) I still do not understand how to inherit from
Extended_homogeneous kernel and why  the syntax would be different than
inheriting from the homogeneous kernel.

- Johannes

On Tue, 2012-04-24 at 08:37 +0200, Sebastien Loriot (GeometryFactory)
wrote:
> On 04/23/2012 02:55 PM, 
> 
>  wrote:
> > I'm trying the add one property to the point class.
> >
> > By help from  StackOverflow I was directed to Manual Chapter 11.5 
> > Extensible
> > Kernel using this I wrote the code below.
> >
> > The code  will not compile and I get the error:
> > ‘typename CGAL::Extended_homogeneous::Base’ names
> > 'CGAL::Extended_homogeneous::Base’, which is not a class template|
> >
> > == CODE ==
> > #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_>  >
> > {};
> >
> > #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<K_>::Type" it
> > will compile but Then I miss the propeties from Extentensions I guess? 
> > Because
> > I get the error "Constructor not available for this kernel" when I run the
> > program.
> 
> The point constructors are not changed by this mechanism. This means 
> that only those documented are available. If you want to initialize your 
> extra data, you need to first create an object of type My_point and then 
> init a point of type MyKernel::Point_3 with it.
> 
> The class in the kernel is a kind of interface while My_point is the
> representation.
> 
> Sebastien.
> 
> 
> 
>