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Implementing class methods in C

I am having a problem implementing some methods of a python class in C.
The class is defined in python, but I would like to rewrite some methods
in c. Here is an example of what I want to do:

file _test.c:

#include <Python.h>

static PyObject *
func2(PyObject *self, PyObject *args)
if (self == NULL) {
PyErr_SetString(PyExc_SystemError, "self is NULL");
return NULL;

// Parse arguments
if (!PyArg_ParseTuple(args, ""))
return NULL;

return Py_None;

static PyMethodDef TestMethods[] = {
{"func2", func2, METH_VARARGS, "func2."},
{NULL, NULL, 0, NULL} /* Sentinel */

(void) Py_InitModule("_test", TestMethods);


class Test:
def func1(self):
print "I am in func 1"

import _test
import new
Test.func2 = new.instancemethod(_test.func2, None, Test)

t = Test()
When I run test.py, I get a SystemError exception (which is what I raise
if self is NULL). I think my confusion lies in the use of PyObject* self
in the function declaration. Shouldn't this be set to point to the
instance of class Test that I am calling it from? Am I misunderstanding
the purpose of PyObject* self? Thanks.


Naveen Michaud-Agrawal
Program in Molecular Biophysics
Johns Hopkins University
(410) 614 4435
Aug 15 '05 #1
0 1318

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