On Wed, 2007-06-20 at 00:21 +1000, Campbell Barton wrote:
> I want to add my own call's before and after PyLists standard functions
> but have a proplem with functons that use keywords and have no API
> equivalent.
> For example, I cant use the API's PyList_Sort because that dosnt support
> keywords like...
>
> ls.sort(key=lambda a: a.foo))
>
> And the Problem with PyObject_CallMethod is that it dosnt accept keywords.
Note that you can always simply call PyObject_Call on the bound method
object retrieved using PyObject_GetAttrString. The hardest part is
usually constructing the keywords dictionary, a job best left to
Py_BuildValue and friends. When I need that kind of thing in more than
one place, I end up with a utility function like this one:
/* Equivalent to PyObject_CallMethod but accepts keyword args. The
format... arguments should produce a dictionary that will be passed
as keyword arguments to obj.method.
Usage example:
PyObject *res = call_method(lst, "sort", "{s:O}", "key", keyfun));
*/
PyObject *
call_method(PyObject *obj, const char *methname, char *format, ...)
{
va_list va;
PyObject *meth = NULL, *args = NULL, *kwds = NULL, *ret = NULL;
args = PyTuple_New(0);
if (!args)
goto out;
meth = PyObject_GetAttrString(obj, methname);
if (!meth)
goto out;
va_start(va, format);
kwds = Py_VaBuildValue(format, va);
va_end(va);
if (!kwds)
goto out;
ret = PyObject_Call(meth, args, kwds);
out:
Py_XDECREF(meth);
Py_XDECREF(args);
Py_XDECREF(kwds);
return ret;
}
It would be nice for the Python C API to support a more convenient way
of calling objects and methods with keyword arguments.
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
http://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
