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
# util.py - Utilities for declaring interfaces.
#
# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
# zope.interface imposes a run-time cost due to module import overhead and
# bookkeeping for declaring interfaces. So, we use stubs for various
# zope.interface primitives unless instructed otherwise.
from __future__ import annotations
from .. import encoding
if encoding.environ.get(b'HGREALINTERFACES'):
from ..thirdparty.zope import interface as zi
Attribute = zi.Attribute
Interface = zi.Interface
implementer = zi.implementer
else:
class Attribute:
def __init__(self, __name__, __doc__=b''):
pass
class Interface:
def __init__(
self, name, bases=(), attrs=None, __doc__=None, __module__=None
):
pass
def implementer(*ifaces):
def wrapper(cls):
return cls
return wrapper