The lmake.import_machinery module

fix_import()

This should be called before importing any module that may be dynamically generated.

It updates the import mechanism to ensure that a dep is set to the source file when importing a module, even if such source file does not exist (yet). Without fix, when a statement import foo is executed, although foo.py is read if it exists, python does not attempt to access it if it does not exist. This is embarassing if foo.py is dynamically produced as initially, it does not exist and if no attempt is made to access it, there will be no dep on it and it will not be built.

module_suffixes

This variable holds the list of suffixes used to generate deps when importing a module and lmake.import_machinery.fix_import() has been called.

It is better to reduce this list to what is really needed in you flow, i.e. the list of suffixes used for generated python modules (modules that are sources are not concerned by this list and deps to them will be accurate in all cases). Reducing this list avoids useless deps.

The default value is the full standard list, e.g. ('/__init__.cpython-312-x86_64-linux-gnu.so','/__init__.abi3.so','/__init__.so','/__init__.py','.cpython-312-x86_64-linux-gnu.so','.abi3.so','.so','.py') for python3.12 running on Linux with a x86_64 processor architecture.

This standard list is constructed as follows:

• Call importlib.machinery.all_suffixes().
• Reorder to put suffixes ending with .so before those ending in .py to match actual python try order.
• Then use 2 copies of this list, the first one being prefixed with /__init__ for each entry (again, python gives priority to packages over leaf modules).

Reasonable values could be:

• ('/__init__.so','/__init__.py','.so','.py') if compiled packages and modules are used locally.
• ('/__init__.py','.py') if no modules nor packages are compiled.
• ('.py',) if no packages is used locally nor modules compiled.

Note that the management of .pyc files is independent.