Get started¶

flake8-lazy helps keep import-time overhead low by detecting imports that can be declared as lazy in __lazy_modules__. For this package itself, flake8-lazy --help runs roughly twice as fast when using Python 3.15's new lazy import system (following PEP 810).

Error messages will mention __lazy_modules__, but the lazy keyword is supported too.

Installation¶

python -m pip install flake8-lazy

Usually you would include this in some sort of dependency-group in your project, e.g. dev or lint. There's also a standalone runner. If you use uv or pipx, you can run it from anywhere without installation:

uvx flake8-lazy <filenames>
# OR
pipx run flake8-lazy <filenames>

Run through flake8¶

flake8 your_package

The plugin is auto-discovered by flake8 via entry points.

Run through pre-commit¶

flake8-lazy ships a pre-commit hook, so you can run the standalone checker without installing it into your environment. Add it to your .pre-commit-config.yaml:

- repo: https://github.com/henryiii/flake8-lazy
  rev: v0.8.1
  hooks:
    - id: flake8-lazy

By default the hook only reports diagnostics. To have it rewrite files in place, pass --apply:

- repo: https://github.com/henryiii/flake8-lazy
  rev: v0.8.1
  hooks:
    - id: flake8-lazy
      args: [--apply=list]

Next steps¶

• Rule reference — all LZY error codes
• Examples — common patterns and diagnostics
• CLI mode — standalone runner and --apply auto-fix
• How it works — detection logic and lazy-capable imports

Acknowledgements¶

GitHub Copilot in VS Code was used to help develop this package. The Scientific Python Development Guide template was used as a starting point.