On 8/22/11 11:51 AM, Matthew Brett wrote: > Hi, > > I recently ran into this behavior: > >>>> import sys >>>> import apkg.subpkg >>>> del sys.modules['apkg'] >>>> import apkg.subpkg as subpkg > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > AttributeError: 'module' object has no attribute 'subpkg' > > where 'apkg' and 'subpkg' comprise empty __init__.py files to simplify the > example. > > It appears then, that importing a subpackage, then deleting the containing > package from sys.modules, orphans the subpackage in an unfixable state. > > I ran into this because the nose testing framework does exactly this kind of > thing when loading test modules, causing some very confusing errors and > failures. > > Is this behavior expected?
Yes. Doing an import of "apkg.subpkg" results in more then just "test1" being cached in sys.modules, and you're removing half of that so leaving Python in a weird state. You also want to del sys.modules["apkg.subpkg"], then you'll be able to re-import apkg.subpkg. I.e: Python 2.7.1 (r271:86882M, Nov 30 2010, 10:35:34) [GCC 4.2.1 (Apple Inc. build 5664)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> import test1.test2 >>> del sys.modules['test1'] >>> del sys.modules['test1.test2'] >>> import test1.test2 as test2 >>> -- Stephen Hansen ... Also: Ixokai ... Mail: me+list/python (AT) ixokai (DOT) io ... Blog: http://meh.ixokai.io/
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