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- import os
- import sys
- import platform
- from typing import Union
- __all__ = ['install', 'NullFinder']
- 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
- 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
- if sys.version_info >= (3, 9):
- StrPath = Union[str, os.PathLike[str]]
- else:
- # PathLike is only subscriptable at runtime in 3.9+
- StrPath = Union[str, "os.PathLike[str]"] # pragma: no cover
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