platform : linux mint 17 / osx 10.11.3

example.c : the C extension function(s)

Method I (hand made)

1. Write wrap.c (for connecting C to python.)

There are 3 parts in wrap.c
A. Exported function

• Deal with function forms in C, should be one of the following
  • PyObject *MyFunction(PyObject *self, PyObject *args);
  • PyObject *MyFunctionWithKeywords(PyObject *self, PyObject *args, PyObject *kw);
  • PyObject *MyFunctionWithNoArgs(PyObject *self);
• Deal with args parsing while programming in C.

B. Method list
C. Initialization function

• Initialization function have different forms in python 2.x and 3.x
• Some structure members of PyModuleDef could just set as default value, check it while programming.

2. Write setup.py (for building C files.)

To avoid platform dependency problem, I strongly suggested to use python lib "distutils".

for python 2.x
$ python setup.py build

for python 3.x
$ python3 setup.py build

then go to "./build/" to find what you need.

enter python 2.x / 3.x

>>> import example
>>> example.fact(6)
720

Method II (ctypes in python)

build

$ gcc -fPIC -o example.so -shared example.c

enter python 2.x / 3.x

>>> from ctypes import *
>>> example = cdll.LoadLibrary("./example.so")
>>> example.fact(6)
720

Deal with args parsing by using ctypes while programming in python.

Other methods (for reference)

Others I (swig)

http://swig.org/index.php

0. install swig

1. write example.i

swig use example.i to generate wrap.c

2. run swig

$ swig -python -o wrap.c example.i
You can omit this step by fill in swig parameters in setup.py

3. Write setup.py (for building C files.)

To avoid platform dependency problem, I strongly suggested to use python lib "distutils".
distutils support swig.

Others II (boost.python)

http://www.boost.org/doc/libs/master/libs/python/doc/html/index.html
If you are familiar with boost lib, try this.

Others III (cython)

http://cython.org/
Infact, cython is another language but very similiar to python.

More details :

for wrap.c
https://docs.python.org/2.7/extending/index.html#extending-index
https://docs.python.org/2.7/c-api/index.html
https://docs.python.org/3.5/extending/index.html#extending-index
https://docs.python.org/3/c-api/index.html
for setup.py
https://docs.python.org/2/distutils/apiref.html
https://docs.python.org/3.5/distutils/apiref.html

for ctypes
https://docs.python.org/2/library/ctypes.html
https://docs.python.org/3.5/library/ctypes.html

write fit with both python 2.x and 3.x
http://python3porting.com/cextensions.html

Note :

• reference counter
• callback