| import platform |
| import sys |
|
|
| __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): |
| del finder.find_distributions |
|
|
|
|
| class NullFinder: |
| """ |
| A "Finder" (aka "MetaPathFinder") 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 |
|
|
