connect & connect_async typing

[cepedus]

Hello, when using the methods connect or connect_async, the return types are lost because of the untyped decorators _async_connection_factory and _connection_factory.

The fix includes the adding of a TypeVar and a ParamSpec to make them coherent with the wrapped callables. This will be usable for all platforms and Python versions >=3.8, using typing_extensions for python < 3.10.

I can tackle the issue if needed :)

[anthony-tuininga]

Thanks for the details. I'll let @cjbj comment on whether he would like your assistance with this issue. Can you, however, share some details on how the current code fails? A quick test with mypy doesn't reveal any concerns, so I must be missing something!

[cjbj]

Two points:

• We don't want to be dependent any not absolutely needed modules, so I'm not in favor of using typing_extensions. This is for compliance and risk reasons. If this means that only 3.10+ have this feature, then we can live with that.
• Any contribution will need the OCA signed first.

[cepedus]

Hello @anthony-tuininga, here is a minimal script:

from typing import TYPE_CHECKING, Any

import oracledb


def get_connection() -> oracledb.Connection:
    conn_params: dict[str, Any] = {}
    return oracledb.connect(**conn_params)


def get_async_connection() -> oracledb.AsyncConnection:
    conn_params: dict[str, Any] = {}
    return oracledb.connect_async(**conn_params)


if TYPE_CHECKING:
    reveal_type(oracledb.connect)
    reveal_type(oracledb.connect_async)

The output of mypy on Python 3.10 is the following:

note: Revealed type is "Any"
note: Revealed type is "Any"

Using mypy --strict on Python 3.10 we get the error itself on the return statement lines:

error: Returning Any from function declared to return "Connection"  [no-any-return]
error: Returning Any from function declared to return "AsyncConnection"  [no-any-return]

---

@cjbj I have just signed the OCA, it is marked as "Under review" :)

[cepedus]

Actually, testing in local there is no need for ParamSpec. The improvement can be done for all supported Python versions