diff --git a/Lib/importlib/util.py b/Lib/importlib/util.py index f1bb4b1fb41576..c94a148e4c50e0 100644 --- a/Lib/importlib/util.py +++ b/Lib/importlib/util.py @@ -178,15 +178,17 @@ def __getattribute__(self, attr): # Only the first thread to get the lock should trigger the load # and reset the module's class. The rest can now getattr(). if object.__getattribute__(self, '__class__') is _LazyModule: + __class__ = loader_state['__class__'] + # Reentrant calls from the same thread must be allowed to proceed without # triggering the load again. # exec_module() and self-referential imports are the primary ways this can # happen, but in any case we must return something to avoid deadlock. if loader_state['is_loading']: - return object.__getattribute__(self, attr) + return __class__.__getattribute__(self, attr) loader_state['is_loading'] = True - __dict__ = object.__getattribute__(self, '__dict__') + __dict__ = __class__.__getattribute__(self, '__dict__') # All module metadata must be gathered from __spec__ in order to avoid # using mutated values. @@ -216,8 +218,10 @@ def __getattribute__(self, attr): # Update after loading since that's what would happen in an eager # loading situation. __dict__.update(attrs_updated) - # Finally, stop triggering this method. - self.__class__ = types.ModuleType + # Finally, stop triggering this method, if the module did not + # already update its own __class__. + if isinstance(self, _LazyModule): + object.__setattr__(self, '__class__', __class__) return getattr(self, attr) diff --git a/Lib/test/test_importlib/test_lazy.py b/Lib/test/test_importlib/test_lazy.py index 4d2cc4eb62b67c..5c6e0303528906 100644 --- a/Lib/test/test_importlib/test_lazy.py +++ b/Lib/test/test_importlib/test_lazy.py @@ -196,6 +196,34 @@ def test_lazy_self_referential_modules(self): test_load = module.loads('{}') self.assertEqual(test_load, {}) + def test_lazy_module_type_override(self): + # Verify that lazy loading works with a module that modifies + # its __class__ to be a custom type. + + # Example module from PEP 726 + module = self.new_module(source_code="""\ +import sys +from types import ModuleType + +CONSTANT = 3.14 + +class ImmutableModule(ModuleType): + def __setattr__(self, name, value): + raise AttributeError('Read-only attribute!') + + def __delattr__(self, name): + raise AttributeError('Read-only attribute!') + +sys.modules[__name__].__class__ = ImmutableModule +""") + sys.modules[TestingImporter.module_name] = module + self.assertIsInstance(module, util._LazyModule) + self.assertEqual(module.CONSTANT, 3.14) + with self.assertRaises(AttributeError): + module.CONSTANT = 2.71 + with self.assertRaises(AttributeError): + del module.CONSTANT + if __name__ == '__main__': unittest.main() diff --git a/Misc/NEWS.d/next/Library/2024-03-23-12-28-05.gh-issue-117182.a0KANW.rst b/Misc/NEWS.d/next/Library/2024-03-23-12-28-05.gh-issue-117182.a0KANW.rst new file mode 100644 index 00000000000000..6b3b841d9d5d7b --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-03-23-12-28-05.gh-issue-117182.a0KANW.rst @@ -0,0 +1,2 @@ +Lazy-loading of modules that modify their own ``__class__`` no longer +reverts the ``__class__`` to :class:`types.ModuleType`.