[Tutor] Extension problem

Ali Alhakim alika at spray.se
Fri Aug 10 13:23:35 CEST 2007


I'm quiet new to Python and definitely a beginner in implementing Python extensions in C/C++. I've followed the structure given in the formal Python documentation to write the following code block:

#include <Python.h>

static unsigned int eigenvect_calc(double *min_eps)
 return 5;
static PyObject *cmat_eigv(PyObject *self, PyObject *args)
	double *min_eps;
	unsigned int m;
	if(!PyArg_ParseTuple(args, "d", &min_eps))
		return NULL;
	return Py_BuildValue("I", m);
static PyMethodDef cmat_methods[]=
	{ "eigenvect", cmat_eigv, METH_VARARGS, "Comment"},{NULL, NULL, 0, NULL}

void initcmat(void)
	 (void) Py_InitModule("cmat", cmat_methods);


I have succeeded to build and install this extension using disutils package in the setup.py file below:
from distutils.core import setup
from distutils.extension import Extension
      ext_modules=[Extension('cmat', ['cmatmod.c'])],

But when I try to call eigenvect(3.0) from Python I would receive a core dump:

 6 [main] python 2336 _cygtls::handle_exceptions: Error while dumping state
 (probably corrupted stack)
Segmentation fault (core dumped)

My question is what is wrong with the extension code above? Is it something with reference counting?
I don't know which method is suitable for debugging extension codes. I've tried gdb but I didn't understand the debug information:

(gdb) >>> eigenvect(4.0)

Program received signal SIGSEGV, Segmentation fault.
---Type <return> to continue, or q <return> to quit---
0x6abb248e in libpython2!PyEval_EvalFrameEx () from /usr/bin/libpython2.5dll

/best regards


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