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import sys |
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import platform |
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__all__ = ['install', 'NullFinder'] |
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def install(cls): |
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""" |
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Class decorator for installation on sys.meta_path. |
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Adds the backport DistributionFinder to sys.meta_path and |
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attempts to disable the finder functionality of the stdlib |
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DistributionFinder. |
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""" |
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sys.meta_path.append(cls()) |
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disable_stdlib_finder() |
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return cls |
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def disable_stdlib_finder(): |
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""" |
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Give the backport primacy for discovering path-based distributions |
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by monkey-patching the stdlib O_O. |
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See #91 for more background for rationale on this sketchy |
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behavior. |
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""" |
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def matches(finder): |
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return getattr( |
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finder, '__module__', None |
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) == '_frozen_importlib_external' and hasattr(finder, 'find_distributions') |
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for finder in filter(matches, sys.meta_path): |
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del finder.find_distributions |
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class NullFinder: |
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""" |
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A "Finder" (aka "MetaPathFinder") that never finds any modules, |
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but may find distributions. |
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""" |
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@staticmethod |
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def find_spec(*args, **kwargs): |
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return None |
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def pypy_partial(val): |
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""" |
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Adjust for variable stacklevel on partial under PyPy. |
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Workaround for #327. |
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""" |
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is_pypy = platform.python_implementation() == 'PyPy' |
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return val + is_pypy |
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