[Numpy-discussion] Array Protocol change for Python 2.6
strawman at astraw.com
Fri Jun 9 16:51:57 EDT 2006
Travis Oliphant wrote:
> Andrew Straw wrote:
>> On the one hand, I feel we should keep __array_struct__ behaving
>> exactly as it is now. There's already lots of code that uses it, and
>> it's tremendously useful despite (because of?) it's simplicity. For
>> these of use cases, the __array_descr__ information has already
>> proven unnecessary. I must say that I, and probably others, thought
>> that __array_struct__ would be future-proof. Although the magnitude
>> of the proposed change to add this information to the C-struct
>> PyArrayInterface is minor, it still breaks code in the wild.
> I don't see how it breaks any code in the wild to add an additional
> member to the C-struct. We could easily handle it in new code with a
> flag setting (like Python uses). The only possible problem is
> looking for it when it is not there.
Ahh, thanks for clarifying. Let me paraphrase to make sure I got it
right: given a C-struct "inter" of type PyArrayInterface, if and only if
((inter.flags & HAS_ARRAY_DESCR) == HAS_ARRAY_DESCR) inter could safely
be cast as PyArrayInterfaceWithArrayDescr and thus expose a new member.
This does seem to avoid all the issues and maintain backwards
compatibility. I guess the only potential complaint is that it's a
little C trick which might be unpalatable to the core Python devs, but
it doesn't seem egregious to me.
If I do understand this issue, I'm +1 for the above scheme provided the
core Python devs don't mind.
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