[Pyrex] Inheriting from an externally defined extension type

[Konrad Hinsen]

Consider the following code:

cdef extern from "spam.h":

    ctypedef class spam.Spam [object PySpamObject]:
        cdef int spam

cdef class SpamAndEggs(Spam):

    cdef int eggs

    def __init__(self, spam, eggs):
        self.spam = spam
        self.eggs = eggs

    cdef cook(self):
        print "Frying ", spam, " spam and ", eggs, "eggs."


Compiling this with Pyrex 0.9 yields a C module containing

struct __pyx_vtabstruct_4spam_SpamAndEggs {
  struct None __pyx_base;
  PyObject *((*cook)(struct __pyx_obj_4spam_SpamAndEggs *));
};

There is no "struct None" defined, so the C compiler complains.

A messge in the archive by Paul Prescod from January 14 proposes a patch for 
this problem. After this patch, the above code becomes:

struct __pyx_vtabstruct_4spam_SpamAndEggs {
  struct __pyx_vtabstruct_4spam_Spam __pyx_base;
  PyObject *((*cook)(struct __pyx_obj_4spam_SpamAndEggs *));
};

Unfortunately, struct __pyx_vtabstruct_4spam_Spam isn't defined either, 
because Spam is not a class generated by Pyrex. Later in the C code, there 
are two references to
  __pyx_vtabptr_4spam_Spam;
which doesn't exist either, for the same reason.

Does anyone have a solution or a workaround?

Konrad.
-- 
-------------------------------------------------------------------------------
Konrad Hinsen                            | E-Mail: hinsen at cnrs-orleans.fr
Centre de Biophysique Moleculaire (CNRS) | Tel.: +33-2.38.25.56.24
Rue Charles Sadron                       | Fax:  +33-2.38.63.15.17
45071 Orleans Cedex 2                    | Deutsch/Esperanto/English/
France                                   | Nederlands/Francais
-------------------------------------------------------------------------------