Awesome
flake8-future-annotations
Verifies python 3.8+ files use from __future__ import annotations if a type is used in the module that can be rewritten using PEP 563.
Pairs well with pyupgrade with the --py37-plus flag or higher, since pyupgrade only replaces type annotations with the PEP 563 rules if from __future__ import annotations is present.
The flake8-future-annotations plugin, along with autofixes, is now available in Ruff!
flake8 codes
| Code | Description |
|---|---|
| FA100 | Missing import if a type used in the module can be rewritten using PEP563 |
| FA101 | Missing import when no rewrite using PEP563 is available (see config) |
| FA102 | Missing import when code uses simplified types (list, dict, set, etc) |
Example
import typing as t
from typing import List
def function(a_dict: t.Dict[str, t.Optional[int]]) -> None:
a_list: List[str] = []
a_list.append("hello")
As a result, this plugin will emit:
hello.py:1:1: FA100 Missing from __future__ import annotations but imports: List, t.Dict, t.Optional
After adding the future annotations import, running pyupgrade allows the code to be automatically rewritten as:
from __future__ import annotations
def function(a_dict: dict[str, int | None]) -> None:
a_list: list[str] = []
a_list.append("hello")
Configuration
If the --force-future-annotations option is set, missing from __future__ import annotations will be reported regardless of a rewrite available according to PEP 563; in this case, code FA101 is used instead of FA100.
If the --check-future-annotations option is set, missing from __future__ import annotations will be reported because the following code will error on Python versions older than 3.10 (this check should not be enabled on Python 3.10+):
def function(a_dict: dict[str, int | None]) -> None:
a_list: list[str] = []
a_list.append("hello")
hello.py:1:1: FA102 Missing from __future__ import annotations but uses simplified type annotations: dict, list, union