# swig, Mac OSX, and python3

## 2015/05/14

I had my eye on a new tool, snakemake, that a friend pointed out to me. I decided it was the moment to switch to Python 3.

I installed Python 3 using MacPorts:

<code>sudo port install python34
sudo port select --set python python34
</code>

That seemed pretty easy. The trouble came when I decided that it was also time to start using swig. In short, I was thinking about running some simulations that were conceptually simple but computationally expensive, and writing the heavy lifting sections in C sounded like just the ticket.

I tried to run the example swig files using the library linking commands for OSX. I got an error ld: library not found for -lintl. When I switched back to python27 using port, the compilation and library linking worked just fine.

I found the answer in an out-of-the-way post:

<code> swig -python foo.i
gcc -c foo.c
gcc -c -I/opt/local/Library/Frameworks/Python.framework/Versions/3.4/include/python3.4m foo_wrap.c
ld -bundle -flat_namespace -undefined suppress -o _foo.so foo.o foo_wrap.o
</code>