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/) >
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