There are reasons all those Py libraries with C code didn't just do it in SWIG.

> There are reasons all those Py libraries with C code didn't just do it in SWIG.

And those reasons are?

The point of SWIG is it works across many langs, but this comes at a cost. The SWIG .i and autogen'd C wrapper are extra layers that can get annoying, particularly during debug. Always hated dealing with SWIG'd libs at work. And Python C modules give easier control over Python specifics.

There's no doubt that hand-written language adapter libraries are less noisy than those generated by a tool such as SWIG. The thing is, debugging tool-generated adapter code is typically more category-based than individual use-case based.

IMHO, both approaches have merit depending on the situation. I lean towards using SWIG until and unless the situation warrants a hand-written solution due to the boilerplate nature of these types of libraries.