Aluode/PerceptionLabPortable

1import sys2import platform3 4 5__all__ = ['install', 'NullFinder']6 7 8def install(cls):9    """10    Class decorator for installation on sys.meta_path.11 12    Adds the backport DistributionFinder to sys.meta_path and13    attempts to disable the finder functionality of the stdlib14    DistributionFinder.15    """16    sys.meta_path.append(cls())17    disable_stdlib_finder()18    return cls19 20 21def disable_stdlib_finder():22    """23    Give the backport primacy for discovering path-based distributions24    by monkey-patching the stdlib O_O.25 26    See #91 for more background for rationale on this sketchy27    behavior.28    """29 30    def matches(finder):31        return getattr(32            finder, '__module__', None33        ) == '_frozen_importlib_external' and hasattr(finder, 'find_distributions')34 35    for finder in filter(matches, sys.meta_path):  # pragma: nocover36        del finder.find_distributions37 38 39class NullFinder:40    """41    A "Finder" (aka "MetaPathFinder") that never finds any modules,42    but may find distributions.43    """44 45    @staticmethod46    def find_spec(*args, **kwargs):47        return None48 49 50def pypy_partial(val):51    """52    Adjust for variable stacklevel on partial under PyPy.53 54    Workaround for #327.55    """56    is_pypy = platform.python_implementation() == 'PyPy'57    return val + is_pypy58