Issue #15502: Bring the importlib ABCs into line with the current state of the import protocols given PEP 420. Original patch by Eric Snow.
diff --git a/Lib/importlib/abc.py b/Lib/importlib/abc.py
index 7fcf2de..5e71758 100644
--- a/Lib/importlib/abc.py
+++ b/Lib/importlib/abc.py
@@ -23,6 +23,61 @@
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 @@
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