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Issue #15502: Bring the importlib ABCs into line with the current state of the import protocols given PEP 420. Original patch by Eric Snow.

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This commit is contained in:
Nick Coghlan 2012-08-02 21:26:03 +10:00
parent a90f311d05
commit 8a9080feff
5 changed files with 127 additions and 65 deletions
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82
Lib/importlib/abc.py
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@ -23,6 +23,61 @@ def _register(abstract_cls, *classes):
abstract_cls.register(frozen_cls)
class Finder(metaclass=abc.ABCMeta):
"""Common abstract base class for import finders.
Finder implementations should derive from the more specific
MetaPathFinder or PathEntryFinder ABCs rather than directly from Finder.
"""
def find_module(self, fullname, path=None):
"""An optional legacy 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):
"""Abstract base class for import finders on sys.meta_path."""
@abc.abstractmethod
def find_module(self, fullname, path):
"""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
_register(MetaPathFinder, machinery.BuiltinImporter, machinery.FrozenImporter,
machinery.PathFinder)
class PathEntryFinder(Finder):
"""Abstract base class for path entry finders used by PathFinder."""
@abc.abstractmethod
def find_loader(self, fullname):
"""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.
"""
raise NotImplementedError
_register(PathEntryFinder, machinery.FileFinder)
class Loader(metaclass=abc.ABCMeta):
"""Abstract base class for import loaders."""
@ -40,33 +95,6 @@ class Loader(metaclass=abc.ABCMeta):
raise NotImplementedError
class Finder(metaclass=abc.ABCMeta):
"""Abstract base class for import finders."""
@abc.abstractmethod
def find_loader(self, fullname):
"""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. When present,
`find_loader()` is preferred over `find_module()`.
"""
raise NotImplementedError
@abc.abstractmethod
def find_module(self, fullname, path=None):
"""Abstract method which when implemented should find a module.
The fullname is a str and the optional path is a str or None.
Returns a Loader object. This method is only called if
`find_loader()` is not present.
"""
raise NotImplementedError
_register(Finder, machinery.BuiltinImporter, machinery.FrozenImporter,
machinery.PathFinder, machinery.FileFinder)
class ResourceLoader(Loader):
"""Abstract base class for loaders which can return data from their