flake8-pyi

A plugin for Flake8 that provides specializations for type hinting stub files, especially interesting for linting typeshed.

Refer to this documentation for more details on stub files.

Functionality

1. Adds the .pyi extension to the default value of the --filename command-line argument to Flake8. This means stubs are linted by default with this plugin enabled, without needing to explicitly list every file.

2. Modifies PyFlakes runs for .pyi files to defer checking type annotation expressions after the entire file has been read. This enables support for first-class forward references that stub files use.

3. Provides a number of .pyi-specific warnings that enforce typeshed’s style guide.

Note: Be careful when using this plugin in the same environment as other flake8 plugins, as they might generate errors that are inappropriate for .pyi files (e.g., about missing docstrings). We recommend running flake8-pyi in a dedicated environment in your CI.

Lints provided

This plugin reserves codes starting with Y0. For a full list of lints currently provided by flake8-pyi, see the list of error codes.

Note that several error codes recommend using types from typing_extensions or _typeshed. Strictly speaking, these packages are not part of the standard library. However, these packages are included in typeshed’s stdlib/ directory, meaning that type checkers believe them to be part of the standard library even if this does not reflect the reality at runtime. As such, since stubs are never executed at runtime, types from typing_extensions and _typeshed can be used freely in a stubs package, even if the package does not have an explicit dependency on either typing_extensions or typeshed.

Flake8-pyi’s checks may produce false positives on stubs that aim to support Python 2.

License

MIT

Authors

Originally created by Łukasz Langa and now maintained by Jelle Zijlstra, Alex Waygood, Sebastian Rittau, Akuli, and Shantanu.

See also

• List of error codes
• Changelog
• Information for contributors