Include modules in directories without `__init__.py`

[jstriebel]

Python allows importing modules from directories without __init__.py (implicit namespace packages per PEP 420). However, grimp doesn't find these modules, so import-linter (my actual use-case) silently excludes them from analysis.

This means contracts may not cover the entire codebase with no warning.

Note: Grimp already supports namespace packages for the cross-distribution case (e.g., google.cloud.logging). This issue is different: it's about directories within a regular package that lack __init__.py.

Example

mypackage/
├── __init__.py
├── core.py
├── a/               # no __init__.py
│   └── missing.py   # ← Python can import this
└── b/
    ├── __init__.py
    └── found.py

Python can import mypackage.a.missing:

>>> from mypackage.a import missing  # works

But grimp doesn't see it:

>>> import grimp
>>> graph = grimp.build_graph("mypackage")
>>> "mypackage.a.missing" in graph.modules
False

Suggested fix

Add an option (e.g., include_implicit_namespace_packages = true) to scan the filesystem for .py files in directories without __init__.py and include them in the graph.

If the above is too invasive, at least warn when .py files exist on disk but weren't included in analysis.

Reproduction

mkdir -p mypackage/a mypackage/b
touch mypackage/__init__.py mypackage/core.py
touch mypackage/a/missing.py
touch mypackage/b/__init__.py mypackage/b/found.py

import grimp

graph = grimp.build_graph("mypackage")
print(sorted(m for m in graph.modules))
# ['mypackage', 'mypackage.b', 'mypackage.b.found', 'mypackage.core']
# mypackage.a.missing is missing

Environment

• import-linter: 2.9
• Python: 3.11+

This might be directly related to seddonym/import-linter#295

[seddonym]

Thanks for raising this issue.

Grimp already supports PEP 420 namespace packages. From what I understand of the spec, mypackage.a is not technically a namespace package, it's just missing an __init__.py file.

If you were to delete the mypackage/__init__.py, or if you were to add mypackage/a/__init__.py, I think Grimp will work as you expect. Is there any reason not to do that (genuine question)?