"Brett Calcott" <brett.calcott@[...].nz>  writes:

> >
> > lvalue_from_pytype is a simple template; take a look.  You could write
> > an extract function which does the same thing, but which uses your
> > non-constant PyTypeObject* expression in place of the template
> > parameter, and register that just the way the lvalue_from_pytype
> > constructor does.
> >
> 
>  Uh yeah. That wasn't so hard.
> 
>  A bit of messing around with your template got me this:
> 
>  template <class Extractor>
>  struct lvalue_from_nonconst_pytype
>  {
>      lvalue_from_nonconst_pytype(PyTypeObject *type)
>      {
>          // assume this is called only once
>          m_type = type;
>          converter::registry::insert(
>              &extract, detail::extractor_type_id(&Extractor::execute));
>      }
>   private:
>      static PyTypeObject *m_type;
> 
>      static void* extract(PyObject* op)
>      {
>          return PyObject_TypeCheck(op, m_type)
>              ? const_cast<void*>(
>                  static_cast<void const volatile*>(
> 
>  detail::normalize<Extractor>(&Extractor::execute).execute(op)))
>              : 0
>              ;
>      }
>  };
> 
>  template <class Extractor> PyTypeObject *
>      lvalue_from_nonconst_pytype<Extractor>::m_type = 0;
> 
> 
>  BOOST_PYTHON_MODULE(test)
>  {
>      import_pygame_rect();
>      lvalue_from_nonconst_pytype<extract_identity<PyRectObject> >
>          need_this_or_msvc_barfs(&PyRect_Type);
> 
>      ...etc...
> 
>  }

Wow, for some reason I couldn't see a generic solution and didn't
think of doing it that way.  That's totally cool!  Maybe I should
change the implementation in the library to allow non-const
PyTypeObjects.  It's more flexible, after all.


>  I am having great fun :)

I'm very pleased :)

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com


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