[Python-Dev] 2.5 and beyond

[Thomas Heller]

Neal Norwitz schrieb:
> I'm glad to see Anthony ratcheting down.  At this point, we need to be
> fixing bugs and improving doc.  Maybe Anthony and I should have a
> contest to see who can revert the most changes. :-)
> 
Neal (and/or Anthony),

I would like to ask about the possibility to add some improvements to ctypes
in Python 2.5, although the feature freeze is now in effect.  Hopefully former
third-party libraries can have the freeze relaxed somewhat;-).

I intend to do these changes, the first is a small and trivial one, but allows
a lot of flexibility:

- Remove the restriction that the argtypes attribute of foreign functions must
  be ctypes types.  Instead they are only required to implement a .from_param
  class method.  The advantage is that custom objects can be used as function
  parameters.  One usecase is to allow numpy arrays as function parameters
  without any conversion - this change at least allows to code this in Python.
  The patch is attached as from_param.patch.

The second one is more involved, and not yet complete.  I can post the patch
or a link to it for review when it is implemented completely:

- Implement the __array_struct__ attribute as describes by the numpy pep at
  http://numpy.scipy.org/array_interface.html.  The properties needed to implement
  the __array_struct__ attribute could be calculated from a given ctypes array type,
  however, it would be more efficient to calculate them at type creation time.
  This requires the StgDSictObject that holds information about the ctypes type
  to grow a few fields: 'int nd' - contains the number of dimensions,
  'char typekind' - a struct-like character for the item type, and
  'Py_intptr_t *shape' - an array of size 'nd' containing shape information.

Thanks for investigating this,
Thomas
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