Most IMP modules are mostly written in C++ and provide a Python wrapper. However, it is also possible to write modules entirely in Python. To do this,

• add python_only=True to the module's dependencies.py file.
• don't provide a SWIG input file (swig.i-in) in the module's pyext directory (it will be ignored).
• provide an __init__.py in the module's pyext/src directory if needed.
• any programs in the module's bin subdirectory should be Python scripts.
• utility C++ headers can still be provided in the module's include directory but no .cpp files can be included in the src directory.

The advantage of making a Python-only module is that it is much faster to build (since it does not need to be compiled).

For good examples, see the test, sampcon, and saxs_merge modules.