Skip to main content

A flake8 plugin to ban PEP-420 implicit namespace packages.

Project description pre-commit

A flake8 plugin to ban PEP-420 implicit namespace packages.


Python 3.8 to 3.12 supported.


First, install with pip:

python -m pip install flake8-no-pep420

Second, if you define Flake8’s select setting, add the INP prefix to it. Otherwise, the plugin should be active by default.

Linting a Django project? Check out my book Boost Your Django DX which covers Flake8 and many other code quality tools.


Implicit namespace packages are directories of Python files without an They’re valid and importable, but they break many tools, such as:

In most cases, tools fail silently, which can lead to a false sense of security:

  • Tests may look legitimate but never run

  • Code may be untested but not appear in coverage statistics

  • Types may never be checked

PEP-420’s algorithm is non-trivial which is probably why such tools haven’t (yet) implemented it.


INP001: File is part of an implicit namespace package. Add

flake8-no-pep420 will trigger this on the first line of any file that sits in a directory without an file.

Often projects have a few root files not in packages, for which an file should not be added. For example, Django projects normally have a file in the root of their repository. In these cases you can ignore the INP001 error. It’s possible to use # noqa: INP001 to ignore the error in-line, but this isn’t possible if the first line is a shebang, such as in Django’s In such cases it’s preferable to use Flake8’s per-file-ignores option, for example in setup.cfg:

# ...
per-file-ignores =

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

flake8_no_pep420-2.7.0.tar.gz (5.3 kB view hashes)

Uploaded Source

Built Distribution

flake8_no_pep420-2.7.0-py3-none-any.whl (4.7 kB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page