flake8-pep585

flake8-pep585

This plugin enforces the changes proposed by PEP 585.

What does PEP 585 change?

Before PEP 585, you had to import stuff from typing to annotate some objects from the standard library:

• For context managers, you'd import typing.ContextManager
• For lists, you'd import typing.List
• For callables, you'd import typing.Callable
• ...and so on

With PEP 585, you can now use classes already present in the standard library. For example:

• For a context manager giving an int, use contextlib.AbstractContextManager[int]
• For a list of dicts mapping strs to ints, use list[dict[str, int]]
• For a callable taking a float and returning an int, use collections.abc.Callable[[float], int]

typing.List, typing.Callable etc. are now deprecated. This is pretty hard to discover, since these imports don't cause a deprecation warning. IDEs don't help either: the "auto-import" feature often suggests importing a deprecated item.

This plugin lets you find these deprecated imports.

Examples

Direct import

from typing import Callable

PEA001 typing.Callable is deprecated, use collections.abc.Callable instead. See PEP 585 for details

Qualified import

from datetime import time
import typing as ty

def construct_time(match: ty.Match) -> time:
    return time(
        hour=int(match["hour"]),
        minute=int(match["minute"]),
    )

PEA001 typing.Match is deprecated, use re.Match instead. See PEP 585 for details

Installation

1. Make sure you have flake8 installed
2. Run pip install flake8-pep585
3. Run flake8 on your code

Configuration

Via your setup.cfg file:

[flake8]
pep585-activation = always  # "always", "auto" or "never"

# Symbols that you're okay with being imported from `typing`
pep585-whitelisted-symbols =
    Callable
    Match
    Pattern

Via the CLI:

python -m flake8 --pep585-activation=always your_project/file.py

This only changes how the plugin behaves on Python 3.7.x and Python 3.8.x. By default ("auto"), it will be enabled if a from __future__ import annotations line is found.