interfaces: convert the zope `Attribute` attrs to regular fields
At this point, we should have a useful protocol class.
The file syntax requires the type to be supplied for any fields that are
declared, but we'll leave the complex ones partially unspecified for now, for
simplicity. (Also, the things documented as `Callable` are really as future
type annotating worked showed- roll with it for now, but they're marked as TODO
for fixing later.) All of the fields and all of the attrs will need type
annotations, or the type rules say they are considered to be `Any`. That can be
done in a separate pass, possibly applying the `dirstate.pyi` file generated
from the concrete class.
The first cut of this turned the `interfaceutil.Attribute` fields into plain
fields, and thus the types on them. PyCharm flagged a few things as having
incompatible signatures when the concrete dirstate class subclassed this, when
the concrete class has them declared as `@property`. So they've been changed to
`@property` here in those cases. The remaining fields that are decorated in the
concrete class have comments noting the differences. We'll see if they need to
be changed going forward, but leave them for now. We'll be in trouble if the
`@util.propertycache` is needed, because we can't import that module here at
runtime, due to circular imports.
# demandimportpy3 - global demand-loading of modules for Mercurial
#
# Copyright 2017 Facebook Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""Lazy loading for Python 3.6 and above.
This uses the new importlib finder/loader functionality available in Python 3.5
and up. The code reuses most of the mechanics implemented inside importlib.util,
but with a few additions:
* Allow excluding certain modules from lazy imports.
* Expose an interface that's substantially the same as demandimport for
Python 2.
This also has some limitations compared to the Python 2 implementation:
* 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
from . import tracing
_deactivated = False
class _lazyloaderex(importlib.util.LazyLoader):
"""This is a LazyLoader except it also follows the _deactivated global and
the ignore list.
"""
_HAS_DYNAMIC_ATTRIBUTES = True # help pytype not flag self.loader
def exec_module(self, module):
"""Make the module load lazily."""
with tracing.log('demandimport %s', module):
if _deactivated or module.__name__ in ignores:
# Reset the loader on the module as super() does (issue6725)
module.__spec__.loader = self.loader
module.__loader__ = self.loader
self.loader.exec_module(module)
else:
super().exec_module(module)
class LazyFinder:
"""A wrapper around a ``MetaPathFinder`` that makes loaders lazy.
``sys.meta_path`` finders have their ``find_spec()`` called to locate a
module. This returns a ``ModuleSpec`` if found or ``None``. The
``ModuleSpec`` has a ``loader`` attribute, which is called to actually
load a module.
Our class wraps an existing finder and overloads its ``find_spec()`` to
replace the ``loader`` with our lazy loader proxy.
We have to use __getattribute__ to proxy the instance because some meta
path finders don't support monkeypatching.
"""
__slots__ = ("_finder",)
def __init__(self, finder):
object.__setattr__(self, "_finder", finder)
def __repr__(self):
return "<LazyFinder for %r>" % object.__getattribute__(self, "_finder")
# __bool__ is canonical Python 3. But check-code insists on __nonzero__ being
# defined via `def`.
def __nonzero__(self):
return bool(object.__getattribute__(self, "_finder"))
__bool__ = __nonzero__
def __getattribute__(self, name):
if name in ("_finder", "find_spec"):
return object.__getattribute__(self, name)
return getattr(object.__getattribute__(self, "_finder"), name)
def __delattr__(self, name):
return delattr(object.__getattribute__(self, "_finder"), name)
def __setattr__(self, name, value):
return setattr(object.__getattribute__(self, "_finder"), name, value)
def find_spec(self, fullname, path, target=None):
finder = object.__getattribute__(self, "_finder")
try:
find_spec = finder.find_spec
except AttributeError:
loader = finder.find_module(fullname, path)
if loader is None:
spec = None
else:
spec = importlib.util.spec_from_loader(fullname, loader)
else:
spec = find_spec(fullname, path, target)
# Lazy loader requires exec_module().
if (
spec is not None
and spec.loader is not None
and getattr(spec.loader, "exec_module", None)
):
spec.loader = _lazyloaderex(spec.loader)
return spec
ignores = set()
def init(ignoreset):
global ignores
ignores = ignoreset
def isenabled():
return not _deactivated and any(
isinstance(finder, LazyFinder) for finder in sys.meta_path
)
def disable():
new_finders = []
for finder in sys.meta_path:
new_finders.append(
finder._finder if isinstance(finder, LazyFinder) else finder
)
sys.meta_path[:] = new_finders
def enable():
new_finders = []
for finder in sys.meta_path:
new_finders.append(
LazyFinder(finder) if not isinstance(finder, LazyFinder) else finder
)
sys.meta_path[:] = new_finders
@contextlib.contextmanager
def deactivated():
# This implementation is a bit different from Python 2's. Python 3
# maintains a per-package finder cache in sys.path_importer_cache (see
# PEP 302). This means that we can't just call disable + enable.
# If we do that, in situations like:
#
# demandimport.enable()
# ...
# from foo.bar import mod1
# with demandimport.deactivated():
# from foo.bar import mod2
#
# mod2 will be imported lazily. (The converse also holds -- whatever finder
# first gets cached will be used.)
#
# Instead, have a global flag the LazyLoader can use.
global _deactivated
demandenabled = isenabled()
if demandenabled:
_deactivated = True
try:
yield
finally:
if demandenabled:
_deactivated = False