The PyArg_ParseTupleAndKeywords() function is declared as
follows:
int PyArg_ParseTupleAndKeywords(PyObject *arg, PyObject *kwdict,
char *format, char *kwlist[], ...);
The arg and format parameters are identical to those of the
PyArg_ParseTuple() function. The kwdict parameter
is the dictionary of keywords received as the third parameter from the
Python runtime. The kwlist parameter is a NULL-terminated
list of strings which identify the parameters; the names are matched
with the type information from format from left to right. On
success, PyArg_ParseTupleAndKeywords() returns true,
otherwise it returns false and raises an appropriate exception.
Note:
Nested tuples cannot be parsed when using keyword
arguments! Keyword parameters passed in which are not present in the
kwlist will cause TypeError to be raised.
Here is an example module which uses keywords, based on an example by
Geoff Philbrick (philbrick@hks.com):
#include "Python.h"
static PyObject *
keywdarg_parrot(PyObject *self, PyObject *args, PyObject *keywds)
{
int voltage;
char *state = "a stiff";
char *action = "voom";
char *type = "Norwegian Blue";
static char *kwlist[] = {"voltage", "state", "action", "type", NULL};
if (!PyArg_ParseTupleAndKeywords(args, keywds, "i|sss", kwlist,
&voltage, &state, &action, &type))
return NULL;
printf("-- This parrot wouldn't %s if you put %i Volts through it.\n",
action, voltage);
printf("-- Lovely plumage, the %s -- It's %s!\n", type, state);
Py_INCREF(Py_None);
return Py_None;
}
static PyMethodDef keywdarg_methods[] = {
/* The cast of the function is necessary since PyCFunction values
* only take two PyObject* parameters, and keywdarg_parrot() takes
* three.
*/
{"parrot", (PyCFunction)keywdarg_parrot, METH_VARARGS | METH_KEYWORDS,
"Print a lovely skit to standard output."},
{NULL, NULL, 0, NULL} /* sentinel */
};
void
initkeywdarg(void)
{
/* Create the module and add the functions */
Py_InitModule("keywdarg", keywdarg_methods);
}
