Exposing buffer interface for non-extension types?

[Robert Kern]

On 7/20/10 9:39 PM, Ken Watford wrote:
> On Tue, Jul 20, 2010 at 9:26 PM, Robert Kern<robert.kern at gmail.com>  wrote:
>> On 7/20/10 8:38 PM, Ken Watford wrote:
>>>
>>> On Tue, Jul 20, 2010 at 6:58 PM, Stefan Behnel<stefan_ml at behnel.de>
>>>   wrote:
>>>>
>>>> Ken Watford, 21.07.2010 00:09:
>>>>>
>>>>> Is there any way to expose the PEP 3118 buffer interface for objects
>>>>> that aren't extension types?
>>>>
>>>> Given that it's a pure C-level interface, I don't think there would be
>>>> much
>>>> use for that.
>>>
>>> Perhaps, but *why* is it only a pure C-level interface? It's based
>>> on/inspired by the array interface, which was not a pure C-level
>>> interface. Did they simply neglect to provide the functionality due to
>>> lack of obvious use cases, or did they consciously decide to drop thaThat
>>> functionality?
>>
>> Lack of obvious use cases. The primary use case is for C extensions to
>> communicate with each other. SWIG is the odd man out in that it does not
>> create true extension types. While the functionality of the PEP derives from
>> numpy's interface, it's inclusion in Python was largely seen as the
>> extension of the older buffer interface which is also a pure C interface.
>>
>> The Python-level __array_interface__ numpy API is not and will not be
>> deprecated despite some outdated language in the documentation. Please
>> continue to use it.
>
> Thanks, that's good to know. (Someone should probably do something
> about the big red box that says the opposite in the current docs).

I just did. I'm sorry; we had a discussion about that some time ago, and I 
thought we had removed it then.

> I assume the same is true about __array_struct__? Since it *is* an
> extension despite the non-extension types, filling in a structure is a
> little more convenient than building the dictionary.

Yes, __array_struct__ is also not deprecated.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco