[Python-Dev] Deprecating non-Py_ssize_t use of PyArg_ParseTuple

[Victor Stinner]

Le lundi 21 mars 2011 à 15:35 +0100, Stefan Behnel a écrit :
> Victor Stinner, 21.03.2011 15:21:
> > Le lundi 21 mars 2011 à 04:09 +0100, "Martin v. Löwis" a écrit :
> >> Since Python 2.5, we maintain two versions of PyArg_ParseTuple:
> >> one outputting int; the other one outputting Py_ssize_t.
> >>
> >> The former should have been removed in 3.0, but this was forgotten.
> >>
> >> Still, I would like people to move over to the new version, so
> >> that extension modules will typically support 64-bit collections
> >> well. Therefore, I'd like to propose that the int version is deprecated
> >> in 3.3.
> >
> > By the way, what is the status of migration to Py_ssize_t of CPython
> > extensions? I suppose that adding a warning will quickly give an answer.
> 
> You'll get a series of very visible warnings from the C compiler when 
> compiling a non-Py_ssize_t extension on a 64bit platform, which is a rather 
> common platform type these days. So I'd doubt that there are any 
> still-in-use extensions left that have not migrated.

Which instrution does emit a warning? If a module still use int, the
compiler was not emit any warning on call to PyArg_Parse*() because the
size arguments are passed as pointers in the magical "..." argument.

But when you switch to Py_ssize_t, you may get errors because Py_ssize_t
may be casted to a narrower type (like int).

Victor