[Python-checkins] bpo-35673: Add a public alias for namespace package __loader__ attribute (#29049)
warsaw
webhook-mailer at python.org
Wed Oct 20 17:05:34 EDT 2021
https://github.com/python/cpython/commit/876fc7fcec9a79a11546b7588d3683a5ccb4d31c
commit: 876fc7fcec9a79a11546b7588d3683a5ccb4d31c
branch: main
author: Barry Warsaw <barry at python.org>
committer: warsaw <barry at python.org>
date: 2021-10-20T14:05:29-07:00
summary:
bpo-35673: Add a public alias for namespace package __loader__ attribute (#29049)
Rename namespace package __loader__ class to be public.
Make the old name, i.e. _NamespaceLoader, an alias for the public name, for backward compatibility.
files:
A Misc/NEWS.d/next/Library/2021-10-18-18-12-47.bpo-35673.KOkHWe.rst
M Doc/library/importlib.rst
M Lib/importlib/_bootstrap.py
M Lib/importlib/_bootstrap_external.py
M Lib/importlib/abc.py
M Lib/importlib/machinery.py
M Lib/test/test_importlib/test_namespace_pkgs.py
diff --git a/Doc/library/importlib.rst b/Doc/library/importlib.rst
index 19230570f2d5f..a25f5145cac83 100644
--- a/Doc/library/importlib.rst
+++ b/Doc/library/importlib.rst
@@ -1394,6 +1394,24 @@ find and load modules.
.. versionadded:: 3.4
+.. class:: NamespaceLoader(name, path, path_finder):
+
+ A concrete implementation of :class:`importlib.abc.InspectLoader` for
+ namespace packages. This is an alias for a private class and is only made
+ public for introspecting the ``__loader__`` attribute on namespace
+ packages::
+
+ >>> from importlib.machinery import NamespaceLoader
+ >>> import my_namespace
+ >>> isinstance(my_namespace.__loader__, NamespaceLoader)
+ True
+ >>> import importlib.abc
+ >>> isinstance(my_namespace.__loader__, importlib.abc.Loader)
+ True
+
+ .. versionadded:: 3.11
+
+
.. class:: ModuleSpec(name, loader, *, origin=None, loader_state=None, is_package=None)
A specification for a module's import-system-related state. This is
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 889f08f8aeec1..afb95f4e1df86 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -507,9 +507,9 @@ def _init_module_attrs(spec, module, *, override=False):
if spec.submodule_search_locations is not None:
if _bootstrap_external is None:
raise NotImplementedError
- _NamespaceLoader = _bootstrap_external._NamespaceLoader
+ NamespaceLoader = _bootstrap_external.NamespaceLoader
- loader = _NamespaceLoader.__new__(_NamespaceLoader)
+ loader = NamespaceLoader.__new__(NamespaceLoader)
loader._path = spec.submodule_search_locations
spec.loader = loader
# While the docs say that module.__file__ is not set for
diff --git a/Lib/importlib/_bootstrap_external.py b/Lib/importlib/_bootstrap_external.py
index c9692b542a5cc..ef4f23a4b499f 100644
--- a/Lib/importlib/_bootstrap_external.py
+++ b/Lib/importlib/_bootstrap_external.py
@@ -1279,8 +1279,10 @@ def append(self, item):
self._path.append(item)
-# We use this exclusively in module_from_spec() for backward-compatibility.
-class _NamespaceLoader:
+# This class is actually exposed publicly in a namespace package's __loader__
+# attribute, so it should be available through a non-private name.
+# https://bugs.python.org/issue35673
+class NamespaceLoader:
def __init__(self, name, path, path_finder):
self._path = _NamespacePath(name, path, path_finder)
@@ -1291,7 +1293,7 @@ def module_repr(module):
The method is deprecated. The import machinery does the job itself.
"""
- _warnings.warn("_NamespaceLoader.module_repr() is deprecated and "
+ _warnings.warn("NamespaceLoader.module_repr() is deprecated and "
"slated for removal in Python 3.12", DeprecationWarning)
return '<module {!r} (namespace)>'.format(module.__name__)
@@ -1327,6 +1329,10 @@ def get_resource_reader(self, module):
return NamespaceReader(self._path)
+# We use this exclusively in module_from_spec() for backward-compatibility.
+_NamespaceLoader = NamespaceLoader
+
+
# Finders #####################################################################
class PathFinder:
diff --git a/Lib/importlib/abc.py b/Lib/importlib/abc.py
index 0b4a3f8071750..1d6843b2ddd44 100644
--- a/Lib/importlib/abc.py
+++ b/Lib/importlib/abc.py
@@ -213,7 +213,7 @@ def source_to_code(data, path='<string>'):
exec_module = _bootstrap_external._LoaderBasics.exec_module
load_module = _bootstrap_external._LoaderBasics.load_module
-_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter)
+_register(InspectLoader, machinery.BuiltinImporter, machinery.FrozenImporter, machinery.NamespaceLoader)
class ExecutionLoader(InspectLoader):
diff --git a/Lib/importlib/machinery.py b/Lib/importlib/machinery.py
index 9a7757fb6e449..d9a19a13f7b27 100644
--- a/Lib/importlib/machinery.py
+++ b/Lib/importlib/machinery.py
@@ -12,6 +12,7 @@
from ._bootstrap_external import SourceFileLoader
from ._bootstrap_external import SourcelessFileLoader
from ._bootstrap_external import ExtensionFileLoader
+from ._bootstrap_external import NamespaceLoader
def all_suffixes():
diff --git a/Lib/test/test_importlib/test_namespace_pkgs.py b/Lib/test/test_importlib/test_namespace_pkgs.py
index 3fe3ddc589844..f80283233f977 100644
--- a/Lib/test/test_importlib/test_namespace_pkgs.py
+++ b/Lib/test/test_importlib/test_namespace_pkgs.py
@@ -1,5 +1,7 @@
import contextlib
import importlib
+import importlib.abc
+import importlib.machinery
import os
import sys
import unittest
@@ -342,6 +344,11 @@ def test_path_indexable(self):
expected_path = os.path.join(self.root, 'portion1', 'foo')
self.assertEqual(foo.__path__[0], expected_path)
+ def test_loader_abc(self):
+ import foo
+ self.assertTrue(isinstance(foo.__loader__, importlib.abc.Loader))
+ self.assertTrue(isinstance(foo.__loader__, importlib.machinery.NamespaceLoader))
+
if __name__ == "__main__":
unittest.main()
diff --git a/Misc/NEWS.d/next/Library/2021-10-18-18-12-47.bpo-35673.KOkHWe.rst b/Misc/NEWS.d/next/Library/2021-10-18-18-12-47.bpo-35673.KOkHWe.rst
new file mode 100644
index 0000000000000..e7d6a5fa5a910
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-10-18-18-12-47.bpo-35673.KOkHWe.rst
@@ -0,0 +1,4 @@
+Improve the introspectability of the ``__loader__`` attribute for namespace
+packages. :class:`importlib.machinery.NamespaceLoader` is now public, and
+implements the :class:`importlib.abc.InspectLoader` interface. ``_NamespaceLoader``
+is kept for backward compatibility.
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