flake8-noreturn

Flake8 plugin to check for using -> None: type hint for return type. Helps to replace them with -> NoRetun type hint from typing.

Why to use NoReturn type hint?

Using NoReturn type hint:

• is more explicit and helps to avoid confusion with None value,
• helps to avoid bugs when using None as a default value for function arguments.
• helps mypy to detect unreachable code

Installation

Use pip to install the package:

$ pip3 install flake8-noreturn

Usage

$ flake8 .

to select only flake8-noreturn errors:

$ flake8 --select NR .

Rules

Currently, the plugin checks implements only one rule:

NR001 Using -> None. Indicates usage of -> None: type hint for return type.

Examples:

def foo() -> None:
    pass

will raise NR001.

from typing import NoReturn

def foo() -> NoReturn:
    pass

will not raise NR001.

def foo() -> tuple[int, None]:
    return 2, None

will not raise NR001.

Related Projects

There is a flake8-no-types which was a heavy inspiration for this project.

Credits

Thank you adamchainz for the inspiring article and the flake8-no-types which helped me to create this plugin.

License

MIT © Krystian Safjan.