flake8-typing-only-imports 0.1.9

A flake8 plugin that flags imports exclusively used for type annotations

flake8-typing-only-imports

Plugin is still a work in progress

flake8 plugin that helps identify which imports to put into type-checking blocks, and how to adjust your type annotations once imports are moved.

Installation

pip install flake8-typing-only-imports

Codes

Code	Description
TYO100	Import should be moved to a type-checking block
TYO101	Third-party import should be moved to a type-checking block
TYO200	Missing 'from __future__ import annotations' import
TYO201	Annotation is wrapped in unnecessary quotes
TYO300	Annotation should be wrapped in quotes
TYO301	Annotation is wrapped in unnecessary quotes

TYO101 is disabled by default because third-party imports usually aren't a real concern with respect to import circularity issues.

TYO2XX and TYO3XX are mutually exclusive as they represent two different ways of solving the same problem. Make sure to ignore or enable just one of the series.

Motivation

Two common issues when annotating large code bases are:

1. Import circularity issues
2. Annotating not-yet-defined structures

These problems are largely solved by two features:

1. Type checking blocks

   from typing import TYPE_CHECKING
   
   if TYPE_CHECKING:
       # this code is not evaluated at runtime
       from foo import bar
   

2. Forward references
   
   Which can be used, like this

   class Foo:
       def bar(self) -> 'Foo':
           return Foo()
   

   or since PEP563 was implemented, like this:

   from __future__ import annotations
   
   class Foo:
       def bar(self) -> Foo:
           return Foo()
   

   See this excellent stackoverflow response explaining forward references, for more context.

The aim of this plugin is to automate the management of type annotation imports, and the forward references that then become necessary.

As a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml:

- repo: https://gitlab.com/pycqa/flake8
  rev: 3.7.8
  hooks:
  - id: flake8
    additional_dependencies: [flake8-typing-only-imports]

Supporting the project

Leave a ⭐️  if this project helped you!

Contributions are always welcome 👏