I proposed it several years ago on the Python-Dev mailing list and that change was approved in general. The reorganization was deferred because there were several known bugs in the RE engine (fixes for which could potentially be backported) and there were not merged patches waiting for review. Now the patch for atomic groups was merged and bugs was fixed (thanks to Ma Lin).

Both the C code and the Python code for the re module are distributed on few files, which lie down in directories Modules and Lib. It makes difficult to work with all related files because they are intermixed with source files of different modules.

The following changes are planned:

1. Convert the re module into a package. Make sre_* modules its submodules.
2. Move C sources for the _sre module into a separate directory.
3. Extract the code for generating definitions of C constants from definitions of Python constants into a separate script and add it in the Tools/scripts directory (there are precedences: generate_token.py, etc).