On 20 July 2011 21:13, Lisandro Dalcin <dalc...@gmail.com> wrote:
> On 20 July 2011 15:32, mark florisson <markflorisso...@gmail.com> wrote:
>> On 20 July 2011 20:04, Lisandro Dalcin <dalc...@gmail.com> wrote:
>>> On 20 July 2011 13:51, mark florisson <markflorisso...@gmail.com> wrote:
>>>> On 20 July 2011 18:06, Lisandro Dalcin <dalc...@gmail.com> wrote:
>>>>> On 19 July 2011 20:48, Robert Bradshaw <rober...@math.washington.edu>
>>>>> wrote:
>>>>>> On Tue, Jul 19, 2011 at 3:02 PM, Lisandro Dalcin <dalc...@gmail.com>
>>>>>> wrote:
>>>>>>> On 19 July 2011 02:24, Vitja Makarov <vitja.maka...@gmail.com> wrote:
>>>>>>>> 2011/7/18 Robert Bradshaw <rober...@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 <rober...@math.washington.edu>:
>>>>>>>>> On Mon, Jul 18, 2011 at 4:34 PM, Greg Ewing
>>>>>>>>> <greg.ew...@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?
>>>>>
>>>>
>>>> I believe Robert confirmed what you said and added to that that it
>>>> would be an error to have a cpdef extern enum in a .pxd without a
>>>> corresponding .pyx file.
>>>>
>>>
>>> But what an "error" means? Cython is going to fail compilation?
>>> Suppose I develop a package, and at setup.py install time my package
>>> installs somewhere a .pxd full of definitions in such a way that
>>> third-party code can cimport it. Then, while writing the third party
>>> code, you cimport the my package .pxd, and obviously there is no .pyx
>>> for my package, as you are writing YOUR code. What's going to happen
>>> in this case?
>>
>> If you want to use cpdef in your .pxd, it means you want to expose
>> those to Python. This means they must be importable from Python, which
>> means you need an extension module that exposes the constants, which
>> means you need a .pyx. So you ship a (possibly empty) .pyx file along
>> with your .pxd. If you don't want to expose them to Python but only to
>> Cython, don't use cpdef. This compile time error would be issued
>> whenever a user does a cimport of a .pxd file that has a cpdef enum
>> with no corresponding .pyx file, i.e. the pxd is unusable, you
>> wouldn't ship it in the first place.
>>
>
> So supose I want to write a small wrapper for dlopen(), then I do:
>
> # dl.pxd
> cdef from extern from "dlfcn.h":
> cpdef enum: RTLD_GLOBAL
> void * dlopen()(const char *filename, int flag);
>
> # dl.pyx
> def open(filename, mode):
> cdef void *handle = c_dlopen(fiename,handle)
> return <long>handle
>
> Then the "dl" module namespace contains "dlopen" and "RTLD_GLOBAL"
>
> Now, suppose I code my setup.py to build the ext module and install
> dl.pxd as package data.
>
> Now a user runs "pip install dl" and installs my package. She wants to
> reuse my .pxd (installed somewhere) for calling dlopen() in its own
> Cython code:
>
> # user.pyx
> from dl cimport RTLD_GLOBAL, c_dlopen
> dlopen("somelibrary.so", RTLD_GLOBAL)
>
>
> So the user code is going to fail? Then I cannot take advantage of
> cpdef enum for developing my "dl" module, I have to go back to
> manually exposing the enumerations
>
Why can't you ship both dl.pxd and dl.pyx as package data?
>
>
>
> --
> Lisandro Dalcin
> ---------------
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