zope-deferredimport

import sys from zope.deferredimport import deferredImport # Simulate a module that would be slow to import or cause a circular dependency # In a real scenario, 'my_app.utils' might be a separate file/module. sys.modules['my_app.utils'] = type('module', (object,), { 'complex_function': lambda: "Complex function executed!", 'helper_constant': 42, 'another_item': 'hello' }) # Define deferred imports for a target module 'my_app.api' deferredImport( 'my_app.api', 'my_app.utils:complex_function', 'my_app.utils:helper_constant', 'my_app.utils:non_existent_item', # This will raise AttributeError on access ) # At this point, 'my_app.api' exists but its contents are not loaded (lazy) print(f"Is 'my_app.api' in sys.modules? {'my_app.api' in sys.modules}") print(f"Has 'complex_function' been imported yet? {'complex_function' in sys.modules.get('my_app.api', {}).__dict__}") # Accessing 'complex_function' triggers its import from 'my_app.utils' import my_app.api print(f"Value of complex_function: {my_app.api.complex_function()}") print(f"Has 'complex_function' been imported now? {'complex_function' in sys.modules.get('my_app.api', {}).__dict__}") print(f"Value of helper_constant: {my_app.api.helper_constant}") # Accessing a non-existent item will raise an AttributeError as expected try: my_app.api.non_existent_item except AttributeError as e: print(f"Expected error for non-existent item: {e}") # Clean up sys.modules for example isolation (not typically done in app code) del sys.modules['my_app.utils'] del sys.modules['my_app.api']