[Python-Dev] Expose the array interface in Python 2.5? (original) (raw)

Travis E. Oliphant oliphant.travis at ieee.org
Sun Mar 19 06:32:44 CET 2006

Paul Moore wrote:

On 3/17/06, Thomas Heller <theller at python.net> wrote:

Travis E. Oliphant wrote: Would it be possible to add at least the C-struct array interface to the Python arrayobject in time for Python 2.5? I'm very much for that.

Is someone on this list willing to help make it happen? Unfortunately not me - I'm too busy with ctypes, and if the array interface makes it into the core I will have to implement/use that in ctypes too.

The ctypes interface is also another reason I really want a basic array interface into the core.

As the very clever people on this list noticed, I was actually asking two different things because I was really looking for support from people who wanted either one...

What I would really like to see is a very-simple C-object defined (perhaps not even exposed to the Python user but only the extension-module writer).

This C-object would have the structure of NumPy arrays, be inheritable, and define an array_struct method (notice I'm not even asking at this point for a new function-pointer table like the buffer protocol has --- although I think at some point that could be useful and maybe it is even better right now to push for that).

The purpose of the C-object would be so that all extension writers to Python can rely on a simple but general-purpose description of an array that Numeric has established over the past decade.

This C-object already has been somewhat fleshed out and the only real work would be to add support for it on other objects.

If all that is required is a simple C definition added to the Python code, then it seems to me that would be (a) fairly easy, but (b) pretty useless (on the basis that a standards-style PEP like the DB API ones would do much the same, without any code changes).

I think I would like to see a real object that can be inherited from (at least in C extension modules). Again perhaps in Python 2.5, this object is not even intentionally exposed to the Python level.

On the third hand, the PEP referenced from the page you quote (at http://svn.scipy.org/svn/PEP/PEPgenarray.txt) seems to specify an implementation - are you just asking for that to be added to the core? If so, why not submit this as a formal PEP, and see what happens from there? (For this route, one of the Numeric people needs to champion the PEP, IMHO, as only they are qualified to address any points that get raised in general discussion).

The big problem is the release schedule of Python 2.5, I've really wanted to get "something" along these lines going for Python 2.5, but I've not had the time to finish the PEP. So, perhaps I'll tone down the request to a simple C-object with even less defined and put that out.

Frankly, I'm really looking for help from an avid Python-dev person who may have an interest but perhaps not much experience with arrays.

-Travis

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