name : dummy_threading.py """Faux ``threading`` version using ``dummy_thread`` instead of ``thread``. The module ``_dummy_threading`` is added to ``sys.modules`` in order to not have ``threading`` considered imported. Had ``threading`` been directly imported it would have made all subsequent imports succeed regardless of whether ``_thread`` was available which is not desired. """ from sys import modules as sys_modules import _dummy_thread # Declaring now so as to not have to nest ``try``s to get proper clean-up. holding_thread = False holding_threading = False holding__threading_local = False try: # Could have checked if ``_thread`` was not in sys.modules and gone # a different route, but decided to mirror technique used with # ``threading`` below. if '_thread' in sys_modules: held_thread = sys_modules['_thread'] holding_thread = True # Must have some module named ``_thread`` that implements its API # in order to initially import ``threading``. sys_modules['_thread'] = sys_modules['_dummy_thread'] if 'threading' in sys_modules: # If ``threading`` is already imported, might as well prevent # trying to import it more than needed by saving it if it is # already imported before deleting it. held_threading = sys_modules['threading'] holding_threading = True del sys_modules['threading'] if '_threading_local' in sys_modules: # If ``_threading_local`` is already imported, might as well prevent # trying to import it more than needed by saving it if it is # already imported before deleting it. held__threading_local = sys_modules['_threading_local'] holding__threading_local = True del sys_modules['_threading_local'] import threading # Need a copy of the code kept somewhere... sys_modules['_dummy_threading'] = sys_modules['threading'] del sys_modules['threading'] sys_modules['_dummy__threading_local'] = sys_modules['_threading_local'] del sys_modules['_threading_local'] from _dummy_threading import * from _dummy_threading import __all__ finally: # Put back ``threading`` if we overwrote earlier if holding_threading: sys_modules['threading'] = held_threading del held_threading del holding_threading # Put back ``_threading_local`` if we overwrote earlier if holding__threading_local: sys_modules['_threading_local'] = held__threading_local del held__threading_local del holding__threading_local # Put back ``thread`` if we overwrote, else del the entry we made if holding_thread: sys_modules['_thread'] = held_thread del held_thread else: del sys_modules['_thread'] del holding_thread del _dummy_thread del sys_modules