[piokuc]

What's also important is to have a simple, neat API, ideally C API. If you do have it, then writing wrappers for any language, even manually, without SWIG (which is great, but does add complexity to your project's build process), is simple.

[ThePhysicist]

Yes that's a valid point, manually writing bindings for C++ is very hard though (IMHO), as there are many intricacies that you have to keep in mind, and SWIG is really good at automating all of these away. For C-code the story is a bit different because usually the code is much less complex.