CPython source code
This section gives an overview of CPython's code structure and provides a summary of file locations for modules and built-ins.
Source code layout
For a Python module, the typical layout is:
Lib/<module>.py
Modules/_<module>.c (if there's also a C accelerator module)
Lib/test/test_<module>.py
Doc/library/<module>.rst
For an extension module, the typical layout is:
Modules/<module>module.c
Lib/test/test_<module>.py
Doc/library/<module>.rst
For builtin types, the typical layout is:
Objects/<builtin>object.c
Lib/test/test_<builtin>.py
For builtin functions, the typical layout is:
Some exceptions to these layouts are:
built-in type int is at
built-in type str is at
built-in module sys is at
built-in module marshal is at
Windows-only module winreg is at