Exposing a C++ API to Python

I've used both (for the same project): Boost is better integrated with the STL, and especially C++ exceptions. Also, its memory management mechanism (which tries to bridge C++ memory management and Python GC) is way more flexible than SWIG's. However, SWIG has much better documentation, no external dependencies, and if you get the library wrapped in SWIG for Python you're more than half-way there to getting a Java/Perl/Ruby wrapper as well.

I don't think there's a clear-cut choice: for smaller projects, I'd go with Boost.Python again, for larger long-lived projects, the extra investment in SWIG is worth it.

EDIT - the Robin project is sadly abandoned, and won't be much use today

I've used Robin with great success.

Great integration with C++ types, and creates a single .cpp file to compile and include in your shared object.

I suggest SIP. SIP is better than SWIG due to the following reasons:

1. For a given set of files, swig generates more duplicate (overhead) code than SIP. SIP manages to generate less duplicate (overhead) code by using a library file which can be statically or dynamically linked. In other words SIP has better scalability.

2. Execution time of SIP is much less than that of SWIG. Refer Python Wrapper Tools: A Performance Study. Unfortunately link appears broken. I have a personal copy which can be shared on request.