Consistent usage of annotation syntax

[f-schnabel]

Fixes #5835.

Description

Use from __future__ import annotations in all source files using annotations, so we have consistent usage (and not only in ~5 files).
The new annotations are also more readable e.g. Optional[Union[List[str], str]] vs. list[str] | str | None.

Secondly, this issue includes changing from typing import Callable, Sequence, ... to from collections.abc import Callable, Sequence, ... since the ones in the typing module are deprecated. They are interchangeable even for isinstance checks (see also this stackoverflow thread).

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Quick tests passed locally by running ./runtests.sh --quick --unittests --disttests.

[f-schnabel]

There are some special cases, since these subscriptable types are only allowed as annotations but not inside casts. Therefore, cast(Iterable[str], x) fails with collections.abc.Iterable but works for typing.Iterable. For those cases I change it back to typing.Iterable.

[wyli]

thanks, could you please also review the pyupgrade configs
https://github.com/Project-MONAI/MONAI/blob/dev/.pre-commit-config.yaml#L33
maybe there are some options that could be enabled after this PR
https://github.com/asottile/pyupgrade#pep-585-typing-rewrites

[bhashemian]

There are some special cases, since these subscriptable types are only allowed as annotations but not inside casts. Therefore, cast(Iterable[str], x) fails with collections.abc.Iterable but works for typing.Iterable. For those cases I change it back to typing.Iterable.

I see! I believe it is better to ignore those typings instead of keeping a deprecated type.

[f-schnabel]

I think we still need the deprecated types here, since the new ones only work inside annotations, but this is creating a type alias.
https://github.com/Shadow-Devil/MONAI/blob/9f4c8059491af22c7d89f02f8d8ed804206868e3/monai/transforms/spatial/array.py#L111

Also here: https://github.com/Shadow-Devil/MONAI/blob/feature_use_new_annotation_syntax/monai/config/type_definitions.py

[wyli]

looks like it's feasible to ensure the "from __future__ import annotations" via isort config,

MONAI/setup.cfg

Line 157 in 6060a47

[isort]

could you please add this:

add_imports = ["from __future__ import annotations"]
append_only = true

[f-schnabel]

looks like it's feasible to ensure the "from __future__ import annotations" via isort config,

MONAI/setup.cfg

Line 157 in 6060a47

[isort]

could you please add this:

add_imports = ["from __future__ import annotations"]
append_only = true

This now also adds the imports to __init__ and test files.
Should I try to exclude them from isort? But then no import sorting would be happening to those files...

[wyli]

/black
thanks, I think it's good as long as the tools are configured to always enforce the style consistently

[wyli]

/build

[bhashemian]

I think we still need the deprecated types here, since the new ones only work inside annotations, but this is creating a type alias. https://github.com/Shadow-Devil/MONAI/blob/9f4c8059491af22c7d89f02f8d8ed804206868e3/monai/transforms/spatial/array.py#L111

Also here: https://github.com/Shadow-Devil/MONAI/blob/feature_use_new_annotation_syntax/monai/config/type_definitions.py

We have until 2025 to update this!😉 This behavior is accepted in 3.10 where we can define numeric = int | float for instance. Maybe by 2025 we can drop support for <3.10.