[Python-Dev] Word size inconsistencies in C extension modules

["Martin v. Löwis"]

Luke Mewburn schrieb:
> On Mon, Sep 10, 2007 at 07:37:02AM +0200, "Martin v. L?wis" wrote:
>   | In principle, it is possible to deal with these in ParseTuple.
>   | To do so:
>   | a) in configure.in, make a configure-time check to compute the
>   |    size of the type, and possibly its signedness.
>   | b) in _cursesmodule.c, make a conditional define of ATTR_T_FMT,
>   |    which would be either "i" or "l" (or #error if it's neither
>   |    the size of int nor the size of long). Then rely on string
>   |    concatenation in using that define.
> 
> Are there some good examples in the Python source where
> this technique has been used already?

Not directly. A check for the size of a library type can be found
for fpos_t, but there, no ParseTuple depends on it. An example
for using variable formatters (though again not for ParseTuple)
is PY_FORMAT_SIZE_T.

> Or were you proposing a cleaner solution that could be
> experimented with?

More that, yes.

>   | I have a GCC patch which checks for correctness of ParseTuple
>   | calls (in terms of data size) if you are interested.
> 
> Sounds like a useful variation of the standard -Wformat stuff.

Indeed, it's an extension to it. Unfortunately, introducing new kinds
of formats is only possible by editing GCC (and then, the existing
framework is focussed on %-style patterns, so I had to bypass that
framework as well - but there were hooks for doing so).

Regards,
Martin