Issue 9252: PyImport_Import calls import with dummy fromlist (original) (raw)

I have discovered this issue while working on the unit tests for issue 7989. In the first version of the setUp/tearDown overrides, I made a mistake when restoring sys.modules after the test run. The fix was to do

sys.modules.init(saved_sys_modules)

instead of

sys.modules = saved_sys_modules

Interestingly, _pickle.c and pickle.py behaved differently when sys.modules was restored incorrectly: pickle.py, using

import(name, ..) mod = sys.modules[name]

picked up the incorrectly restored sys.modules, while _pickle.c, using PyImport_Import, which is effectively

mod = import(name, fromlist=["doc"], ..)

failed.

From discussion on python-dev [1], I realize that pickle.py approach is the correct one even though in my case it would probably mask an error in my code.

At the minimum, I think _pickle.c and pickle.py should be changed to do the same thing - probably call importlib.import_module(..). I don't know whether PyImport_Import should be fixed or deprecated.

[1] "Peculiar import code in pickle.py" <http://mail.python.org/pipermail/python-dev/2010-July/101906.html>.