[C++-sig] Wrapping multiple class_<T> objects

[David Abrahams]

Peter Bienstman <Peter.Bienstman at rug.ac.be> writes:

> Hello,
>
> I'm trying to wrap a class and two specific instances of it:
>
>   class_<SlabWallMixed, bases<SlabWall> >
>     ("SlabWallMixed", init<const Complex&, const Complex&>());
>
>   object slab_E_wall 
>     = (class_<SlabWallMixed, bases<SlabWall> >
>        ("slab_E_wall", init<const Complex&, const Complex&>()))(1.0,1.0);
>   
>   object slab_H_wall 
>     = (class_<SlabWallMixed, bases<SlabWall> >
>        ("slab_H_wall", init<const Complex&, const Complex&>()))(1.0,-1.0); 
>
> Any of these statements by themselves work fine, but if I combine two or more, 
> I get:
>
> RuntimeError: trying to register to_python_converter for a type which already 
> has a registered to_python_converter
>
> Did I get the syntax wrong or is this currenty impossible?

There are lots of ways to write this so you don't instantiate the same
class_<> twice. One is:


  object slabwallmixed
         = class_<SlabWallMixed, bases<SlabWall> >
            ("SlabWallMixed", init<const Complex&, const Complex&>());

  object slab_E_wall = slabwallmixed(1.0,1.0);
  object slab_H_wall = slabwallmixed(1.0,-1.0); 

-- 
                       David Abrahams
   dave at boost-consulting.com * http://www.boost-consulting.com
Boost support, enhancements, training, and commercial distribution