Still works, at least in some old 3.1 I had lying around: $ python3.1 Python 3.1a0 (py3k:70152, Mar 3 2009, 16:55:42) [GCC 4.0.1 (Apple Inc. build 5465)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import sys >>> sys.modules['string'] = None >>> import string Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: No module named string >>> $ python3.1 Python 3.1a0 (py3k:70152, Mar 3 2009, 16:55:42) [GCC 4.0.1 (Apple Inc. build 5465)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import string >>> $
The experiment should be easily repeatable. :-) --Guido On Thu, Jul 23, 2009 at 8:35 PM, Brett Cannon<br...@python.org> wrote: > > > On Thu, Jul 23, 2009 at 20:18, Guido van Rossum <gu...@python.org> wrote: >> >> So, I guess, we'll live with it for a while longer. Given that it >> managed to evade our attention for so long, I think that's fine. > > Can someone double-check me that the semantics can even be triggered in 3.1? > I just tried and couldn't come up with anything. Heck, I quick search for a > Py_None comparison in 3.1's import.c turned up nothing useful (other than > mark_miss() is the function used to set None in sys.modules). We might have > actually already removed it or made it so that the semantics can't be > triggered. > >> >> I agree that there's no reason for a None result from loaders to be >> interpreted the same way, assuming that's not how it works ATM. >> >> And we can live with import and importlib differing on this in 3.1 >> (though you could call it a bug in importlib and fix it for 3.1.1 -- >> not sure if you were planning on that). > > I can if people can trigger the semantics somehow so I have a test to go by. > -Brett > >> >> --Guido >> >> On Thu, Jul 23, 2009 at 7:50 PM, Brett Cannon<br...@python.org> wrote: >> > >> > >> > On Thu, Jul 23, 2009 at 19:48, Benjamin Peterson <benja...@python.org> >> > wrote: >> >> >> >> 2009/7/23 Brett Cannon <br...@python.org>: >> >> > >> >> > >> >> > On Thu, Jul 23, 2009 at 19:38, Benjamin Peterson >> >> > <benja...@python.org> >> >> > wrote: >> >> >> >> >> >> 2009/7/23 Brett Cannon <br...@python.org>: >> >> >> > None in Python 3.1 is really useless in terms of its semantics in >> >> >> > relative >> >> >> > imports; importlib doesn't support it and still passes as >> >> >> > __import__ >> >> >> > (at >> >> >> > least last time I ran the test suite that way). I thought we had >> >> >> > agreed >> >> >> > a >> >> >> > while back that supporting None was not warranted in Python 3.0? >> >> >> > Otherwise I >> >> >> > will do whatever work is necessary for this to happen. >> >> >> >> >> >> I think it's still nice for the rare cases where you need to trick a >> >> >> module into thinking another one doesn't exist. >> >> > >> >> > But None does not strictly mean "I don't exist". None is supposed to >> >> > trigger >> >> > an another import attempt for the module with a top-level name. It's >> >> > that >> >> > extra import trigger that has no real use in 3.0 and just complicates >> >> > import >> >> > semantics (IMO) needlessly. If you want a module to not exist then >> >> > you >> >> > either stick something else in (e.g. '42') or we remove the special >> >> > semantics for None (which I thought we had). >> >> >> >> >> >> I didn't realize None had other semantics attached to it. (Imagine >> >> that dealing with import!) +1 for making it simply indicate an >> >> ImportError. >> > >> > I'm +0 with having import raise ImportError if None is set in >> > sys.modules as >> > long as we don't suddenly expect loaders to trigger the same thing if >> > they >> > return None (actually, as of right now what loaders return count for >> > nothing, but just want to be clear). >> > -Brett >> >> >> >> -- >> --Guido van Rossum (home page: http://www.python.org/~guido/) > > -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
