[Cython] How to define C-consts in python module scope

Lisandro Dalcin dalcinl at gmail.com
Wed Jul 20 18:06:00 CEST 2011

On 19 July 2011 20:48, Robert Bradshaw <robertwb at math.washington.edu> wrote:
> On Tue, Jul 19, 2011 at 3:02 PM, Lisandro Dalcin <dalcinl at gmail.com> wrote:
>> On 19 July 2011 02:24, Vitja Makarov <vitja.makarov at gmail.com> wrote:
>>> 2011/7/18 Robert Bradshaw <robertwb at math.washington.edu>:
>>>> Trevor King and I discussed this quite a while back, but every time I
>>>> got around to looking at his code (I don't think he ever created a
>>>> formal pull request) something came up. The idea was that we could
>>>> support cpdef structs and extern functions as well.
>>> That's interesting, I think I shouldn't hurry with my pull request.
>>> 2011/7/19 Robert Bradshaw <robertwb at math.washington.edu>:
>>>> On Mon, Jul 18, 2011 at 4:34 PM, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
>>>>> My suggestion is
>>>>>  cdef exposed enum:
>>>>>    ...
>>>> I agree, public is an overloaded word. This meaning is analogous to
>>>> its use for cdef class members. Perhaps we should use "api" for api
>>>> generation, and public used for Python-level access, with cpdef being
>>>> the preferred form for declaring Python-accessible types.
>>> It seems to me that cpdef is more cythonic but exposed could be used
>>> in this case:
>>> cdef extern from "ev.h":
>>>    exposed enum:
>>>        EV_READ
>>>        EV_WRITE
>> And what about this?
>> cdef extern from "ev.h":
>>   cpdef enum:
>>       EV_READ
>>       EV_WRITE
> Yep, exactly.
>> BTW, how is this supposed to work with *.pxd files? I think the values
>> will be exposed just in the matching implementation .pyx file, and not
>> with cimport, right?
> It would be an error unless there's an corresponding .pyx file (which
> could be empty). The idea is that one could also define extern cpdef
> functions and structs and wrappers would be provided.

It would be an error? What do you mean? if you cpdef enum in foo.pxd,
and have foo.pyx, then the enumerations should be exposed in the 'foo'
module. But then if you "cimport foo" in bar.pyx, that should succeed
but the enumerations should not be exposed in the "bar" module... Am I
missing something?

Lisandro Dalcin
Predio CONICET-Santa Fe
Colectora RN 168 Km 472, Paraje El Pozo
3000 Santa Fe, Argentina
Tel: +54-342-4511594 (ext 1011)
Tel/Fax: +54-342-4511169

More information about the cython-devel mailing list