Building Shared Libraries: Python Extension Using C++ and SWIG

Question

I am working through the tutorial examples from http://www.swig.org/ and have run into some problems. I took the following command instructions from the tutorial on swig.org:
http://www.swig.org/tutorial.html
I have written example.c and example.i as described in the above tutorial. My first attempt at compiling the libraries was this:
swig -python example.i
gcc -c example.c example_wrap.c \
-I /System/Library/Frameworks/Python.framework/Versions/Current/Headers
ld -shared example.o example_wrap.o -o _example.so
this last command fails with the following error:
ld: unknown option: -shared
Any help?

Answer 1

Hi, newbie73
I'm also running into trouble with manually linking and creating .so objects using swig.
The good news is, for python there's a shortcut, using the distutils module. Using the example.c and example.i codes from the tutorial, make a python script called 'setup.py':
<pre>
from distutils.core import setup, Extension
setup(name='example',
version='1.0',
ext_modules = [
Extension('example', ['example.c','example.i'] )
</pre>
edit: The discussion markup is messing up this code snippet: line 5 should read:
Extension('example', LEFT BRACKET 'example.c' , 'example.i' ] )
Then run:
python setup.py build_ext
Python will do the compiling and linking for you, and create an example.so file inside a new 'build' directory. To use the .so file, move or rename this file to _example.so in your $PYTHONPATH.
(By the way, I found this information in the excellent textbook Beginning Python by M. Hetland)
I hope that helps!
Caleb
Message was edited by: Caleb Mattoon