[Pythonmac-SIG] OS X C API bug?

[Gary Robinson]

Hello,

The attached file contains a c module with 4 versions of the same 
extremely simple function. All they do is return a float double to 
python. The zip also contains the setup.py to build it.

On Windows I can import the module into Python and run all of them 
successfully.

But on OS X Panther with XCode 1.5 installed, the first 3 work and the 
last 
one causes a bus error. There is no obvious reason why it should do so. 
(At least not to me or the others who have looked at it.) Here's the 
output on Panther:

>>> from check import *
>>> fun0()
411.0
>>> fun1()
534.30000000000007
>>> fun2()
411.0
>>> fun3()
Bus error


I originally reported this on the C++ sig's mail list. They suggested I 
try dev-python. Scott David Daniels on that list helped me refine some 
test cases and verified that they all worked on Windows. He suggested I 
try mac-python next, so here I am. We're thinking it may be 
compiler-related.

The code follows:

#include "Python.h"
static double value = 411.0;

static PyObject *
fun0(PyObject *self, PyObject *args)
{
    if (!PyArg_ParseTuple(args, "", NULL)) return NULL;
    return Py_BuildValue("d", value);
}

static PyObject *
fun1(PyObject *self, PyObject *args)
{
    return Py_BuildValue("d", 1.3*value);
}

static PyObject *
fun2(PyObject *self, PyObject *args)
{
    return PyFloat_FromDouble(value);
}

static PyObject *
fun3(PyObject *self, PyObject *args)
{
    return Py_BuildValue("d", value);
}


static PyMethodDef TestMethods[] = {
    {"fun0", fun0, METH_VARARGS, "Read args and return value"},
    {"fun1", fun1, METH_VARARGS, "Return value multiplied inline by 
1.3"},
    {"fun2", fun2, METH_VARARGS, "Return value using 
PyFloat_FromDouble"},
    {"fun3", fun3, METH_VARARGS, "Return value using Py_BuildValue 
without reading args -- causes bus error on OS X Panther with XCode 1.5 
installed"},
    {NULL, NULL, 0, NULL}        /* Sentinel */
};

PyMODINIT_FUNC
initcheck(void)
{
    PyObject *module;

    module = Py_InitModule3("check", TestMethods,
		"extension module with three functions.");
    if (module) {
	PyModule_AddStringConstant(module, "__version__", "0.02");
    }
}


Any help or insight would be most appreciated.

Gary



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-- 

Gary Robinson
CTO
Emergent Music, LLC
grobinson at goombah.com
207-942-3463
Company: http://www.goombah.com
Blog:    http://www.garyrobinson.net