Hello, I was asking about a problem I was having over on the C++-python list, and they suggested I report it here as a possible Python problem. I was getting bus errors with a C module I was linking to, so factored it down too a very small example that reproduced the problem. Here it is: #include <Python.h> static double gfSumChiSquare = 123.0; static PyObject * getSumChiSquare(PyObject *self, PyObject *args){ return Py_BuildValue("d", gfSumChiSquare); } static PyMethodDef SimMethods[] = { {"getSumChiSquare", getSumChiSquare, METH_NOARGS, "Return fSumChiSquare"}, {NULL, NULL, 0, NULL} /* Sentinel */ }; PyMODINIT_FUNC inittestfloat(void) { (void) Py_InitModule("testfloat", SimMethods); } That caused a bus error 100% of the time when I simply imported the module into Python and called getSumChiSquare(), i.e.:
import testfloat testfloat.getSumChiSquare()
However, the problem seems to go away if I use METH_VARARGS, and parse the non-existent args with PyArg_ParseTuple: #include <Python.h> static double gfSumChiSquare = 123.0; static PyObject * getSumChiSquare(PyObject *self, PyObject *args){ if (!PyArg_ParseTuple(args, "", NULL)) return NULL; return Py_BuildValue("d", gfSumChiSquare); } static PyMethodDef SimMethods[] = { {"getSumChiSquare", getSumChiSquare, METH_VARARGS, "Return fSumChiSquare"}, {NULL, NULL, 0, NULL} /* Sentinel */ }; PyMODINIT_FUNC inittestfloat(void) { (void) Py_InitModule("testfloat", SimMethods); } This approach seems to work reliably -- at least variations I've tried haven't caused a bus error. But I haven't been able to discern an explanation from the docs as to why this would be better. The docs say that both METH_VARARGS and METH_NOARGS expect a PyCFunction. So if I am calling the function with no arguments, why can't I use METH_NOARGS and skip the call to PyArg_ParseTuple? Could it be that this is a python bug? Or am I doing something wrong? Note: this is using Python 2.3 on OS X: Python 2.3 (#1, Sep 13 2003, 00:49:11) Thanks in advance for any help or insight you can give, Gary -- Gary Robinson CTO Emergent Music, LLC grobinson@goombah.com 207-942-3463 Company: http://www.goombah.com Blog: http://www.garyrobinson.net