comparison hgdemandimport/demandimportpy3.py @ 51901:f4733654f144

typing: add `from __future__ import annotations` to most files

Now that py36 is no longer supported, we can postpone annotation evaluation.
This means that the quoting is usually optional (for things imported under the
guard of `if typing.TYPE_CHECKING:` to avoid circular imports), and there's less
overhead on startup[1].

There may be some missing here.  I backed out 6000f5b25c9b (which removed the
`from __future__ import ...` that was supporting py2), reverted the changes in
`contrib/`, `doc/`, and `tests/`, and then ran:

    $ hg status -n --change . | \
        xargs sed -i -e 's/from __future__ import .*$/from __future__ import annotations/'

There were some minor tweaks needed when reviewing (mostly making the spacing
around the import consistent, and `mercurial/testing/__init__.py` had a
multiline import that wasn't fully rewritten.

[1] https://docs.python.org/3/whatsnew/3.7.html#pep-563-postponed-evaluation-of-annotations

51900:607e94e01851

* Much of the logic is per-package, not per-module, so any packages loaded
  before demandimport is enabled will not be lazily imported in the future. In
  practice, we only expect builtins to be loaded before demandimport is
  enabled.
"""

import contextlib
import importlib.util
import sys

51901:f4733654f144

* Much of the logic is per-package, not per-module, so any packages loaded
  before demandimport is enabled will not be lazily imported in the future. In
  practice, we only expect builtins to be loaded before demandimport is
  enabled.
"""

from __future__ import annotations

import contextlib
import importlib.util
import sys