flake8-typing-imports

flake8 plugin which checks that typing imports are properly guarded

installation

pip install flake8-typing-imports

flake8 codes

Code	Description
TYP001	guard import by `TYPE_CHECKING`
TYP002	`@overload` is broken in <3.5.2
TYP003	`Union[Match, ...]` or `Union[Pattern, ...]` must be quoted in <3.5.2
TYP004	`NamedTuple` does not support methods in 3.6.0
TYP005	`NamedTuple` does not support defaults in 3.6.0
TYP006	guard `typing` attribute by quoting

rationale

unfortunately, the typing module has been pretty unstable -- it has seen api changes in 3.5.0, 3.5.2, 3.5.3, 3.5.4, 3.6.0, 3.6.1, 3.6.2, 3.7.0, and 3.7.2!

depending on your supported version of python, you may need to guard your imports by if TYPE_CHECKING: (3.5.2+) or if False: if the things you are importing aren't available in all the pythons you support.

as it's pretty difficult to keep track of what version things changed and you can't always test against particular patch versions of python, this plugin helps you statically check this automatically!

# default / --min-python-version 3.5.0
from typing import Type  # TYP001

# default / --min-python-version 3.5.0
if False:
    from typing import Type  # OK!

# default / --min-python-version 3.5.0
from typing import overload  # TYP002

# default / --min-python-version 3.5.0
import sys
from typing import overload  # OK!
if sys.version_info < (3, 5, 2):
    def overload(f):
        return f

# default / --min-python-version 3.5.0
def foo(bar: Union[Match, str]) -> None: pass  # TYP003
def foo(bar: "Union[Match, str]") -> None: pass  # OK!

def foo(bar: Union[Pattern, str]) -> None: pass  # TYP003
def foo(bar: "Union[Pattern, str]") -> None: pass  # OK!

# --min-python-version 3.6.0
class NT(NamedTuple):
    x: int = 5  # TYP005

    def f(self) -> int:  # TYP004
        return self.x + 4

# --min-python-version 3.7.0
from typing import TYPE_CHECKING
if TYPE_CHECKING:
    from typing import OrderedDict  # OK!

configuration

this plugin has a single configuration point (beyond those provided by flake8) which is the --min-python-version option.

by default, this option is 3.5.0. this includes all versions of python which have the typing module present.

you can also set this option in the flake8 configuration if you don't want to use the commandline:

[flake8]
min_python_version = 3.6.2

if a >= is set for python_requires in setup.cfg, that value will be used:

# setup.cfg setuptools metadata

[options]
python_requires = >=3.6

as a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml: