fix: return "Self" from "BaseRetrying.copy"

[ThirVondukr]

Currently BaseRetrying.copy returns BaseRetrying, making reusing a "template"/base retrying object harder.
Example usecase:

from tenacity import AsyncRetrying


class SomeClient:
    def __init__(self, retry: AsyncRetrying) -> None:
        self._retry = retry

    async def method(self) -> None:
        async for attempt in self._retry.copy():
            with attempt:
                pass  # Do something

$ mypy main.py 
main.py:9: error: "BaseRetrying" has no attribute "__aiter__" (not async iterable)  [attr-defined]
Found 1 error in 1 file (checked 1 source file)

[mergify]

⚠️ No release notes detected. Please make sure to use reno to add a changelog entry.

[ThirVondukr]

@jd On an unrelated note - would a PR that adds a package manager (uv seems to be a good choice nowadays) to setup a dev environment be welcome?
Also would be nice to set up https://docs.pypi.org/trusted-publishers/

[jd]

@jd On an unrelated note - would a PR that adds a package manager (uv seems to be a good choice nowadays) to setup a dev environment be welcome?

Yes, if that can replace tox I'll be happy.

Also would be nice to set up https://docs.pypi.org/trusted-publishers/

I'll work on that at some point, good thing.

[ThirVondukr]

@jd On an unrelated note - would a PR that adds a package manager (uv seems to be a good choice nowadays) to setup a dev environment be welcome?

Yes, if that can replace tox I'll be happy.

If you need to run multiple python environments/versions/dependency versions tox is probably the right choice, but that could instead be done in CI and mypy/ruff seem to work correctly when you specify target version, though you still can run them in CI with all python versions.

[ThirVondukr]

I've checked with mypy, pyright and PyCharm:
PyCharm seems to derive copied type correctly:

Mypy works fine:

from tenacity import AsyncRetrying, Retrying

retrying = AsyncRetrying()
reveal_type(retrying.copy()) # note: Revealed type is "tenacity.asyncio.AsyncRetrying"

retrying_sync = Retrying()
reveal_type(retrying_sync.copy()) # note: Revealed type is "tenacity.Retrying"

Pyright too:

src\main.py:4:13 - information: Type of "retrying.copy()" is "AsyncRetrying"
src\main.py:7:13 - information: Type of "retrying_sync.copy()" is "Retrying"

Typing extensions has section in documentation about using types in runtime: https://typing-extensions.readthedocs.io/en/latest/#runtime-use-of-types
It would only be a problem here if BaseRetrying.copy would be inspected for some reason:

import typing

from tenacity import AsyncRetrying, Retrying

typing.get_type_hints(AsyncRetrying.copy)

but is seems to fail earlier due to StopBaseT not being defined since it's imported in a type-checking block too, so adding Self without typing_extensions doesn't seem to be a problem here.