[Python-Dev] Extending Python 3000 (original) (raw)

Rob Crowther weilawei at gmail.com
Tue Sep 18 23:46:58 CEST 2007

I'm attempting to wrap the GNU MP mpf_t type and related functions, as I need the extra precision and speed for a package I'm writing. The available wrappers are either unmaintained or undocumented and incompatible with Python 3000. Following the docs in the Python 3000 section of the website, I've started off with this:

mpfmodule.c

#include <Python.h> #include <stdio.h> #include <gmp.h>

typedef struct { PyObject_HEAD mpf_t ob_val; } MPFObject;

static PyTypeObject MPFType = { PyObject_HEAD_INIT(NULL) 0, /ob_size/ "mpf.MPF", /tp_name/ sizeof(MPFObject), /tp_basicsize/ 0, /tp_itemsize/ 0, /tp_dealloc/ 0, /tp_print/ 0, /tp_getattr/ 0, /tp_setattr/ 0, /tp_compare/ 0, /tp_repr/ 0, /tp_as_number/ 0, /tp_as_sequence/ 0, /tp_as_mapping/ 0, /*tp_hash / 0, /tp_call/ 0, /tp_str/ 0, /tp_getattro/ 0, /tp_setattro/ 0, /tp_as_buffer/ Py_TPFLAGS_DEFAULT, /tp_flags/ "GNU MP mpf_t objects", / tp_doc */ };

static PyMethodDef mpf_methods[] = { {NULL} };

#ifndef PyMODINIT_FUNC #define PyMODINIT_FUNC void #endif

PyMODINIT_FUNC initmpf(void) { PyObject* m;

MPFType.tp_new = PyType_GenericNew;
if (PyType_Ready(&MPFType) < 0)
    return;

m = Py_InitModule3("mpf", mpf_methods,
                   "Wrapper around GNU MP mpf_t and related methods");

Py_INCREF(&MPFType);
PyModule_AddObject(m, "MPF", (PyObject *) &MPFType);

}

Upon running my setup.py script, it gives me numerous warnings. These do not occur if I attempt to use Python 2.5. It also works fine under Python 2.5.

weilawei at archeron:~/Code/mpf$ python setup.py build running build running build_ext building 'mpf' extension gcc -pthread -fno-strict-aliasing -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -fPIC -DMAJOR_VERSION=1 -DMINOR_VERSION=0 -I/usr/local/include -I/usr/local/include/python3.0 -c mpfmodule.c -o build/temp.linux-i686-3.0 /mpfmodule.o mpfmodule.c:11: warning: missing braces around initializer mpfmodule.c:11: warning: (near initialization for ‘MPFType.ob_base.ob_base’) mpfmodule.c:13: warning: initialization makes integer from pointer without a cast mpfmodule.c:32: warning: initialization from incompatible pointer type gcc -pthread -shared build/temp.linux-i686-3.0/mpfmodule.o -L/usr/local/lib -lgmp -o build/lib.linux-i686-3.0/mpf.so

Inside the Python interpreter:

weilawei at archeron:~/Code/mpf/build/lib.linux-i686-3.0$ python Python 3.0a1 (py3k, Sep 15 2007, 00:33:44) [GCC 4.1.3 20070831 (prerelease) (Ubuntu 4.1.2-16ubuntu1)] on linux2 Type "help", "copyright", "credits" or "license" for more information.

import mpf test = mpf.MPF() Traceback (most recent call last): File "", line 1, in MemoryError mpf.MPF Segmentation fault

Pointers as to what has changed and what I need to do to compile an extension for Py3k would be very much appreciated. Thank you all in advance for your time.

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