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Issue #15502: Finish bringing importlib.abc in line with the current

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state of the import system. Also make importlib.invalidate_caches()
work with sys.meta_path instead of sys.path_importer_cache to
completely separate the path-based import system from the overall
import system.

Patch by Eric Snow.
This commit is contained in:
Brett Cannon 2012-08-10 12:21:12 -04:00
parent 2d6266d5f1
commit f4dc9204cc
8 changed files with 1294 additions and 1207 deletions
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42
Lib/importlib/abc.py
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@ -25,26 +25,22 @@ def _register(abstract_cls, *classes):
class Finder(metaclass=abc.ABCMeta):
"""Common abstract base class for import finders.
"""Legacy abstract base class for import finders.
Finder implementations should derive from the more specific
MetaPathFinder or PathEntryFinder ABCs rather than directly from Finder.
It may be subclassed for compatibility with legacy third party
reimplementations of the import system. Otherwise, finder
implementations should derive from the more specific MetaPathFinder
or PathEntryFinder ABCs.
"""
@abc.abstractmethod
def find_module(self, fullname, path=None):
"""An optional legacy method that should find a module.
"""An abstract method that should find a module.
The fullname is a str and the optional path is a str or None.
Returns a Loader object.
The path finder will use this method only if find_loader() does
not exist. It may optionally be implemented for compatibility
with legacy third party reimplementations of the import system.
"""
raise NotImplementedError
# invalidate_caches() is a completely optional method, so no default
# implementation is provided. See the docs for details.
class MetaPathFinder(Finder):
@ -52,12 +48,18 @@ class MetaPathFinder(Finder):
@abc.abstractmethod
def find_module(self, fullname, path):
"""Abstract method which when implemented should find a module.
"""Abstract method which, when implemented, should find a module.
The fullname is a str and the path is a str or None.
Returns a Loader object.
"""
raise NotImplementedError
def invalidate_caches(self):
"""An optional method for clearing the finder's cache, if any.
This method is used by importlib.invalidate_caches().
"""
return NotImplemented
_register(MetaPathFinder, machinery.BuiltinImporter, machinery.FrozenImporter,
machinery.PathFinder, machinery.WindowsRegistryFinder)
@ -68,13 +70,25 @@ class PathEntryFinder(Finder):
@abc.abstractmethod
def find_loader(self, fullname):
"""Abstract method which when implemented returns a module loader.
"""Abstract method which, when implemented, returns a module loader.
The fullname is a str. Returns a 2-tuple of (Loader, portion) where
portion is a sequence of file system locations contributing to part of
a namespace package. The sequence may be empty.
a namespace package. The sequence may be empty and the loader may be
None.
"""
raise NotImplementedError
def find_module(self, fullname):
"""Compatibility function which is the equivalent of
self.find_loader(fullname)[0]."""
return self.find_loader(fullname)[0]
def invalidate_caches(self):
"""An optional method for clearing the finder's cache, if any.
This method is used by PathFinder.invalidate_caches().
"""
return NotImplemented
_register(PathEntryFinder, machinery.FileFinder)