You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
73 lines
1.8 KiB
Python
73 lines
1.8 KiB
Python
import sys
|
|
import platform
|
|
|
|
|
|
__all__ = ['install', 'NullFinder', 'Protocol']
|
|
|
|
|
|
try:
|
|
from typing import Protocol
|
|
except ImportError: # pragma: no cover
|
|
# Python 3.7 compatibility
|
|
from typing_extensions import Protocol # type: ignore
|
|
|
|
|
|
def install(cls):
|
|
"""
|
|
Class decorator for installation on sys.meta_path.
|
|
|
|
Adds the backport DistributionFinder to sys.meta_path and
|
|
attempts to disable the finder functionality of the stdlib
|
|
DistributionFinder.
|
|
"""
|
|
sys.meta_path.append(cls())
|
|
disable_stdlib_finder()
|
|
return cls
|
|
|
|
|
|
def disable_stdlib_finder():
|
|
"""
|
|
Give the backport primacy for discovering path-based distributions
|
|
by monkey-patching the stdlib O_O.
|
|
|
|
See #91 for more background for rationale on this sketchy
|
|
behavior.
|
|
"""
|
|
|
|
def matches(finder):
|
|
return getattr(
|
|
finder, '__module__', None
|
|
) == '_frozen_importlib_external' and hasattr(finder, 'find_distributions')
|
|
|
|
for finder in filter(matches, sys.meta_path): # pragma: nocover
|
|
del finder.find_distributions
|
|
|
|
|
|
class NullFinder:
|
|
"""
|
|
A "Finder" (aka "MetaClassFinder") that never finds any modules,
|
|
but may find distributions.
|
|
"""
|
|
|
|
@staticmethod
|
|
def find_spec(*args, **kwargs):
|
|
return None
|
|
|
|
# In Python 2, the import system requires finders
|
|
# to have a find_module() method, but this usage
|
|
# is deprecated in Python 3 in favor of find_spec().
|
|
# For the purposes of this finder (i.e. being present
|
|
# on sys.meta_path but having no other import
|
|
# system functionality), the two methods are identical.
|
|
find_module = find_spec
|
|
|
|
|
|
def pypy_partial(val):
|
|
"""
|
|
Adjust for variable stacklevel on partial under PyPy.
|
|
|
|
Workaround for #327.
|
|
"""
|
|
is_pypy = platform.python_implementation() == 'PyPy'
|
|
return val + is_pypy
|