interfaces: introduce and use a protocol class for the `bdiff` module
This is allowed by PEP 544[1], and we basically follow the example there. The
class here is copied from `mercurial.pure.bdiff`, and the implementation
removed.
There are several modules that have a few different implementations, and the
implementation chosen is controlled by `HGMODULEPOLICY`. The module is loaded
via `mercurial/policy.py`, and has been inferred by pytype as `Any` up to this
point. Therefore it and PyCharm were blind to all functions on the module, and
their signatures. Also, having multiple instances of the same module allows
their signatures to get out of sync.
Introducing a protocol class allows the loaded module that is stored in a
variable to be given type info, which cascades through the various places it is
used. This change alters 11 *.pyi files, for example. In theory, this would
also allow us to ensure the various implementations of the same module are kept
in alignment- simply import the module in a test module, attempt to pass it to a
function that uses the corresponding protocol as an argument, and run pytype on
it.
In practice, this doesn't work (yet). PyCharm (erroneously) flags imported
modules being passed where a protocol class is used[2]. Pytype has problems the
other way- it fails to detect when a module that doesn't adhere to the protocol
is passed to a protocol argument. The good news is that mypy properly detects
this case. The bad news is that mypy spews a bunch of other errors when
importing even simple modules, like the various `bdiff` modules. Therefore I'm
punting on the tests for now because the type info around a loaded module in
PyCharm is a clear win by itself.
[1] https://peps.python.org/pep-0544/#modules-as-implementations-of-protocols
[2] https://youtrack.jetbrains.com/issue/PY-58679/Support-modules-implementing-protocols
# __init__.py - narrowhg extension
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
'''create clones which fetch history data for subset of files (EXPERIMENTAL)'''
from __future__ import annotations
from mercurial import (
localrepo,
registrar,
requirements,
)
from . import (
narrowbundle2,
narrowcommands,
narrowrepo,
narrowtemplates,
narrowwirepeer,
)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b'ships-with-hg-core'
configtable = {}
configitem = registrar.configitem(configtable)
# Narrowhg *has* support for serving ellipsis nodes (which are used at
# least by Google's internal server), but that support is pretty
# fragile and has a lot of problems on real-world repositories that
# have complex graph topologies. This could probably be corrected, but
# absent someone needing the full support for ellipsis nodes in
# repositories with merges, it's unlikely this work will get done. As
# of this writining in late 2017, all repositories large enough for
# ellipsis nodes to be a hard requirement also enforce strictly linear
# history for other scaling reasons.
configitem(
b'experimental',
b'narrowservebrokenellipses',
default=False,
alias=[(b'narrow', b'serveellipses')],
)
# Export the commands table for Mercurial to see.
cmdtable = narrowcommands.table
def featuresetup(ui, features):
features.add(requirements.NARROW_REQUIREMENT)
def uisetup(ui):
"""Wraps user-facing mercurial commands with narrow-aware versions."""
localrepo.featuresetupfuncs.add(featuresetup)
narrowbundle2.setup()
narrowcommands.setup()
narrowwirepeer.uisetup()
def reposetup(ui, repo):
"""Wraps local repositories with narrow repo support."""
if not repo.local():
return
repo.ui.setconfig(b'experimental', b'narrow', True, b'narrow-ext')
if requirements.NARROW_REQUIREMENT in repo.requirements:
narrowrepo.wraprepo(repo)
narrowwirepeer.reposetup(repo)
templatekeyword = narrowtemplates.templatekeyword
revsetpredicate = narrowtemplates.revsetpredicate