Use from __future__ import annotations across all code

[dimaqq]

Current status: discussion

from __future__ import annotations means we don't have to quote many type hints:

-    def from_dict(cls, d: '_SystemInfoDict') -> 'SystemInfo':
+    def from_dict(cls, d: _SystemInfoDict) -> SystemInfo:

Which originally stems from this:

if TYPE_CHECKING:
    from typing_extensions import NotRequired

I would argue that we should use new (py 3.10+) type hinting machinery and write our code almost as if it were for py 3.10+ only.

[tonyandrewmeyer]

In general, I'm in favour of using __future__ imports as early as possible.

My one concern here is that it's uncertain when the behaviour will become the default, or if it will change before that happens. However, my knowledge here is very limited (reading over the docs just now, and listing to a few podcast episodes talking about this quite some time back that I only partially recall). I'm not even sure what the current situation is - the docs link to the 3.11 postponement but not to anything about 3.12 or 3.13.

[tonyandrewmeyer]

With from __future__ import annotations we can change our types to be in the form a: int | str | None = 42 rather than a: Optional[Union[int, str]] = 42, and still support Python 3.8, right? I didn't realise this before today. If that is correct, then I'm 💯 in favour of this, even with the ultimate status of the PEP still in question.

[benhoyt]

Ooh, yes, if what Tony's saying is the case, I'd be in favour of this too. Let's confirm that and then do this. Can Pyright or Ruff or something automate the conversion?

[tonyandrewmeyer]

Can Pyright or Ruff or something automate the conversion?

pyupgrade can. Ruff has pyupgrade's checks, so maybe it also can?

[tonyandrewmeyer]

See also canonical/ops-scenario#203 for this being done in Scenario.