Issue #14646: __import__() now sets __loader__ if need be.

importlib.util.module_for_loader also will set __loader__ along with
__package__. This is in conjunction to a forthcoming update to PEP 302
which will make these two attributes required for loaders to set.

2 files changed, 53 insertions, 3 deletions

diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 2b26003..3153f21 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -257,9 +257,14 @@ def module_for_loader(fxn):
 
     The decorated function is passed the module to use instead of the module
     name. The module passed in to the function is either from sys.modules if
-    it already exists or is a new module which has __name__ set and is inserted
-    into sys.modules. If an exception is raised and the decorator created the
-    module it is subsequently removed from sys.modules.
+    it already exists or is a new module. If the module is new, then __name__
+    is set the first argument to the method, __loader__ is set to self, and
+    __package__ is set accordingly (if self.is_package() is defined) will be set
+    before it is passed to the decorated function (if self.is_package() does
+    not work for the module it will be set post-load).
+
+    If an exception is raised and the decorator created the module it is
+    subsequently removed from sys.modules.
 
     The decorator assumes that the decorated function takes the module name as
     the second argument.
@@ -274,7 +279,18 @@ def module_for_loader(fxn):
             # infinite loop.
             module = _new_module(fullname)
             sys.modules[fullname] = module
+            module.__loader__ = self
+            try:
+                is_package = self.is_package(fullname)
+            except (ImportError, AttributeError):
+                pass
+            else:
+                if is_package:
+                    module.__package__ = fullname
+                else:
+                    module.__package__ = fullname.rpartition('.')[0]
         try:
+            # If __package__ was not set above, __import__() will do it later.
             return fxn(self, module, *args, **kwargs)
         except:
             if not is_reload:
@@ -1012,6 +1028,12 @@ def _find_and_load(name, import_):
                 module.__package__ = module.__package__.rpartition('.')[0]
         except AttributeError:
             pass
+    # Set loader if need be.
+    if not hasattr(module, '__loader__'):
+        try:
+            module.__loader__ = loader
+        except AttributeError:
+            pass
     return module
 
 
diff --git a/Lib/importlib/test/test_util.py b/Lib/importlib/test/test_util.py
index b035d65..7963e4f 100644
--- a/Lib/importlib/test/test_util.py
+++ b/Lib/importlib/test/test_util.py
@@ -79,6 +79,34 @@ class ModuleForLoaderTests(unittest.TestCase):
             given = self.return_module(name)
             self.assertTrue(given is module)
 
+    def test_attributes_set(self):
+        # __name__, __loader__, and __package__ should be set (when
+        # is_package() is defined; undefined implicitly tested elsewhere).
+        class FakeLoader:
+            def __init__(self, is_package):
+                self._pkg = is_package
+            def is_package(self, name):
+                return self._pkg
+            @util.module_for_loader
+            def load_module(self, module):
+                return module
+
+        name = 'pkg.mod'
+        with test_util.uncache(name):
+            loader = FakeLoader(False)
+            module = loader.load_module(name)
+            self.assertEqual(module.__name__, name)
+            self.assertIs(module.__loader__, loader)
+            self.assertEqual(module.__package__, 'pkg')
+
+        name = 'pkg.sub'
+        with test_util.uncache(name):
+            loader = FakeLoader(True)
+            module = loader.load_module(name)
+            self.assertEqual(module.__name__, name)
+            self.assertIs(module.__loader__, loader)
+            self.assertEqual(module.__package__, name)
+
 
 class SetPackageTests(unittest.TestCase):