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
Index: _ctypes.c
===================================================================
RCS file: /cvsroot/ctypes/ctypes/source/_ctypes.c,v
retrieving revision 1.340
diff -u -r1.340 _ctypes.c
--- _ctypes.c 22 Jun 2006 19:21:28 -0000 1.340
+++ _ctypes.c 4 Jul 2006 09:56:06 -0000
@@ -1633,9 +1633,8 @@
for (i = 0; i < nArgs; ++i) {
PyObject *tp = PyTuple_GET_ITEM(ob, i);
- StgDictObject *dict = PyType_stgdict(tp);
PyObject *cnv = PyObject_GetAttrString(tp, "from_param");
- if (!dict || !cnv)
+ if (!cnv)
goto argtypes_error_1;
PyTuple_SET_ITEM(converters, i, cnv);
}
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