On Jul 7, 2009, at 11:15 AM, David Simmons-Duffin wrote:
> I'm trying to interface with some C code that defines a type called
> "object"
The type "object" is used to denote a Python object (essentially a
refcounted PyObject*), which is why you're having trouble redefining it.
> typedef union {
> struct {
> objtype type; reftype nref;
> } any;
> intcel i;
> bigint b;
> vector v;
> matrix m;
> poly pl;
> simpgrp s;
> group g;
> tekst t;
> } objcel, *object;
>
> However, if I try to write some cython code involving an object:
>
> cdef extern object groupmake(char lietype, int rank)
> cdef object g
> g = groupmake("A", 3)
>
> It's interpreted as a PyObject in the c code:
>
> PyObject *__pyx_t_1 = NULL;
> ...
> __pyx_t_1 = groupmake('A', 2);
>
> One possible solution is to just replace the word "object" in the C
> source with something else throughout. But I'd like to make as few
> modifications of the C source as possible. Is there an alternate
> solution?
Yes, you can use the magic c-namespace-renaming quotes. For your
example.
cdef extern from *:
ctypedef int objtype
ctypedef int reftype
ctypedef int intcel
cdef struct any_struct:
objtype type
reftype nref
ctypedef union objcel:
any_struct any
intcel i
...
ctypedef objcel *my_c_object "object"
Now use my_c_object, and in the c sources it will come out as object.
>
> I actually have another unrelated question: what is the correct cython
> syntax for the union statement at the top of this message? Cython
> doesn't seem to like me putting
>
> struct any:
> objtype type
> reftype nfref
>
> in the middle of a union statement.
Cython doesn't support anonymous structs. Give that struct a name,
and then you can declare your variable with that type. (The name you
choose will never actually be used.)
> And I'm also not sure what to do
> with "objcel, *object" at the end there. I'm a novice at this stuff,
> so apologies if these are stupid questions.
No worries. The only stupid questions are those that should have been
answered by a couple minutes of googling and reading the wiki. These
ones don't fall into that boat.
Just out of curiosity, what are you wrapping? It looks like a math
library of sorts.
- Robert
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