Small inconsistency between string.split and "".split

[Michael Hudson]

aleaxit at yahoo.com (Alex Martelli) writes:

> Michael Hudson <mwh at python.net> wrote:
> 
> > aleaxit at yahoo.com (Alex Martelli) writes:
> > 
> > > Having ALL C-coded functions and methods that accept any argument
> > > accept keyword-style arguments in particular would surely lead to a
> > > more consistent language,
> > 
> > [...]
> > 
> > This whole area isn't particularly pretty.  In general it would be
> 
> Indeed, it isn't.
> 
> > better to expose more of an extension functions signature *outside*
> > the function, for efficiency, introspection and even things like
> 
> ...and consistency with the way Python-coded functions work.

Heh, yes, that too :-)

> > psyco.  METH_O, METH_NOARGS are a step in this direction -- but you
> > can't pass a keyword argument to a METH_O function (not that one would
> > want to, very often, but it's still a potential inconsistency).
> 
> Right; it could be remedied by letting a macro otherwise equivalent to
> METH_O know about that one argument's name.

But... how?  I guess the PyMethodDef struct could grow an ml_signature
field... wouldn't it be nice if you could do:

static PyObject*
foo(PyObject* ob, int index)
{
        ...;
}

PyMethodDef methods[] = {
        {"foo", foo, "O[ob]i[index]", "docstring"},
        {NULL, NULL}
}

?  Even nicer if you didn't have to write the signature by hand.

Unfortunately, I don't think you can do this in standard C.
> > I wonder what Pyrex does...
> 
> for:
> def example(aa, bb):
>     pass
> 
> it generates (name mangling apart, I'm demangling for legibility):
> 
> static PyObject* example(PyObject *self, PyObject *args, PyObject *kwds)
> {
>     PyObject *aa = 0;
>     PyObject *bb = 0;
>     static char *argnames[] = {"aa", "bb", 0};
> 
>     if(!PyArg_ParseTupleAndKeywords(args,kwds,"OO",argnames,&aa,&bb))
>         return 0;
> 
> etc, etc, and METH_VARARGS|METH_KEYWORDS in the PyMethodDef array.  IOW,
> nothing strange, and all correct, it seems to me.

Cool.  I should use pyrex more, I suspect.

Cheers,
mwh

-- 
 As it seems to me, in Perl you have to be an expert to correctly make
 a nested data structure like, say, a list of hashes of instances.  In
 Python, you have to be an idiot not  to be able to do it, because you
 just write it down.             -- Peter Norvig, comp.lang.functional