view mercurial/typelib.py @ 49818:3fd5824f1177

typing: attempt to remove @overloads in the platform module for stdlib methods

This is mostly successful, as examining util.pyi, posix.pyi, and windows.pyi
after a pytype run shows that the type overloads for `oslink`, `readlink`,
`removedirs`, `rename`, `split`, and `unlink` have been removed.  (Some of these
still have an @overload, but the differences are the variable names, not the
types.)  However, @overloads remain for `abspath` and `normpath` for some
reason.

It's useful to redefine these methods for the type checking phase because in
addition to excluding str and PathLike variants, some of these functions have
optional args in stdlib that aren't implemented in the custom implementation on
Windows, and we want the type checking to flag that instead of assuming it's an
allowable overload everywhere.

One last quirk I noticed that I can't explain- `pycompat.TYPE_CHECKING` is
always False, so the conditionals need to check `typing.TYPE_CHECKING` directly.
I tried dropping the custom code for assigning `pycompat.TYPE_CHECKING` and
simply did `from typing import TYPE_CHECKING` directly in pycompat.py, and used
`pycompat.TYPE_CHECKING` for the conditional here... and pytype complained that
`pycompat` doesn't have the `TYPE_CHECKING` variable.

# typelib.py - type hint aliases and support
#
# Copyright 2022 Matt Harbison <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import typing

# Note: this is slightly different from pycompat.TYPE_CHECKING, as using
# pycompat causes the BinaryIO_Proxy type to be resolved to ``object`` when
# used as the base class during a pytype run.
TYPE_CHECKING = typing.TYPE_CHECKING


# The BinaryIO class provides empty methods, which at runtime means that
# ``__getattr__`` on the proxy classes won't get called for the methods that
# should delegate to the internal object.  So to avoid runtime changes because
# of the required typing inheritance, just use BinaryIO when typechecking, and
# ``object`` otherwise.
if TYPE_CHECKING:
    from typing import (
        BinaryIO,
    )

    BinaryIO_Proxy = BinaryIO
else:
    BinaryIO_Proxy = object