fix-future-annotations

A CLI and pre-commit hook to upgrade the typing annotations syntax to PEP 585 and PEP 604.

Upgrade Details

PEP 585 – Type Hinting Generics In Standard Collections

typing.Dict[str, int]
List[str]

dict[str, int]
list[str]

PEP 604 – Allow writing union types as X | Y

typing.Union[str, int]
Optional[str]

str | int
str | None

PEP 563 – Postponed Evaluation of Annotations

def create() -> "Foo": pass

def create() -> Foo: pass

Import aliases handling

import typing as t
from typing import Tuple as MyTuple

def foo() -> MyTuple[str, t.Optional[int]]:
    pass

from __future__ import annotations

import typing as t

def foo() -> tuple[str, int | None]:
    pass

Full example

from typing import Union, Dict, Optional, Tuple

# non-annotation usage will be preserved
MyType = Union[str, int]


def foo() -> Tuple[Dict[str, int], Optional[str]]:
    ...

from __future__ import annotations

from typing import Union

# non-annotation usage will be preserved
MyType = Union[str, int]


def foo() -> tuple[dict[str, int], str | None]:
    ...

Unused import names will be removed, and if from __future__ import annotations is not found in the script, it will be automatically added if the new syntax is being used.

Use as pre-commit hook

Add the following to your .pre-commit-config.yaml:

repos:
  - repo: https://github.com/frostming/fix-future-annotations
    rev: x.y.z  # a released version tag
    hooks:
      - id: fix-future-annotations

Use as command line tool

python3 -m pip install -U fix-future-annotations

fix-future-annotations my_script.py

License

This work is distributed under MIT license.