Change importlib.machinery.PathFinder to not have implicit semantics (that's
not handled by importlib._bootstrap._DefaultPathFinder).
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 54e2f9d..1b4053d 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -610,36 +610,25 @@
"""Meta path finder for sys.(path|path_hooks|path_importer_cache)."""
- _default_hook = staticmethod(chaining_fs_path_hook(ExtensionFileImporter,
- PyFileImporter))
-
- # The list of implicit hooks cannot be a class attribute because of
- # bootstrapping issues for accessing imp.
@classmethod
- def _implicit_hooks(cls):
- """Return a list of the implicit path hooks."""
- return [cls._default_hook, imp.NullImporter]
+ def _path_hooks(cls, path, hooks=None):
+ """Search sequence of hooks for a finder for 'path'.
- @classmethod
- def _path_hooks(cls, path):
- """Search sys.path_hooks for a finder for 'path'.
-
- Guaranteed to return a finder for the path as NullImporter is the
- default importer for any path that does not have an explicit finder.
+ If 'hooks' is false then use sys.path_hooks.
"""
- for hook in sys.path_hooks + cls._implicit_hooks():
+ if not hooks:
+ hooks = sys.path_hooks
+ for hook in hooks:
try:
return hook(path)
except ImportError:
continue
else:
- # This point should never be reached thanks to NullImporter.
- raise SystemError("no hook could find an importer for "
- "{0}".format(path))
+ raise ImportError("no path hook found for {0}".format(path))
@classmethod
- def _path_importer_cache(cls, path):
+ def _path_importer_cache(cls, path, default=None):
"""Get the finder for the path from sys.path_importer_cache.
If the path is not in the cache, find the appropriate finder and cache
@@ -657,9 +646,9 @@
finder = cls._path_hooks(path)
sys.path_importer_cache[path] = finder
else:
- if finder is None:
+ if finder is None and default:
# Raises ImportError on failure.
- finder = cls._default_hook(path)
+ finder = default(path)
sys.path_importer_cache[path] = finder
return finder
@@ -680,6 +669,30 @@
return None
+class _DefaultPathFinder(PathFinder):
+
+ """Subclass of PathFinder that implements implicit semantics for
+ __import__."""
+
+ _default_hook = staticmethod(chaining_fs_path_hook(ExtensionFileImporter,
+ PyFileImporter))
+
+ @classmethod
+ def _path_hooks(cls, path):
+ """Search sys.path_hooks as well as implicit path hooks."""
+ try:
+ return super()._path_hooks(path)
+ except ImportError:
+ implicit_hooks = [cls._default_hook, imp.NullImporter]
+ return super()._path_hooks(path, implicit_hooks)
+
+ @classmethod
+ def _path_importer_cache(cls, path):
+ """Use the default path hook when None is stored in
+ sys.path_importer_cache."""
+ return super()._path_importer_cache(path, cls._default_hook)
+
+
class ImportLockContext(object):
"""Context manager for the import lock."""
@@ -693,6 +706,8 @@
imp.release_lock()
+_IMPLICIT_META_PATH = [BuiltinImporter, FrozenImporter, _DefaultPathFinder]
+
def _gcd_import(name, package=None, level=0):
"""Import and return the module based on its name, the package the call is
being made from, and the level adjustment.
@@ -736,8 +751,7 @@
# Backwards-compatibility; be nicer to skip the dict lookup.
parent_module = sys.modules[parent]
path = parent_module.__path__
- meta_path = (sys.meta_path +
- [BuiltinImporter, FrozenImporter, PathFinder])
+ meta_path = sys.meta_path + _IMPLICIT_META_PATH
for finder in meta_path:
loader = finder.find_module(name, path)
if loader is not None: