[Python-Dev] getter/setter function signatures
Martin v. Loewis
18 Apr 2002 14:47:27 +0200
"Thomas Heller" <email@example.com> writes:
> At least descrobject.c, cPickle.c and funcobject.c defines PyGetSetDef
> arrays which use function signatures where the last void* parameter is
> missing. While obviously this does no harm (so far), it is surely a bug
> (or am I missing something)?
In the sense of strict C, this is a bug - the function is called with
the closure present, so it must also be declared with the closure.
Most C implementations support calls where the caller provides more
arguments than the callee consumes, for compatibility with K&R C, so
this is not a problem. Still, it should be changed, IMO.
> Related: I am always wondering, why the compiler (MSVC 6 in my case)
> gives a warning when you use these signatures for getter/setter functions
> PyObject *get(wrapperobject *, void *)
> int set(wrapperobject *, PyObject *, void *)
> (warning C4028: formal parameter 1 different from declaration),
> while if I use these signatures
> PyObject *get(PyObject *)
> int set(PyObject *, PyObject *)
> the compilation gives no warning at all. Another MSVC glitch?
MSVC is right when giving the warnings about the first set of
signatures: You cannot convert PyObject*(*)(wrapperobject*,void*) to
Apparently, it sees no problem with the conversion of
PyObject*(*)(PyObject*) to PyObject*(*)(PyObject*,void*), which,
again, could be for compatibility with K&R C (function pointer type
can be converted if the argument types of one function are an initial
sequence of the argument types of the other).
Just see whether compiling in strict C mode changes anything.