On Fri, Oct 25, 2013 at 1:15 PM, Brett Cannon <br...@python.org> wrote: > > On Fri, Oct 25, 2013 at 12:24 PM, PJ Eby <p...@telecommunity.com> wrote: >> At least through all 2.x, reload() just uses module.__name__ to >> restart the module find-and-load process, and does not assume that >> __loader__ is valid in advance. > > > That doesn't make much sense in a post-importlib world where import makes > sure that __loader__ is set (which it has since Python 3.3). Otherwise you > are asking for not just a reload but a re-find as well.
That's a feature, not a bug. A reload() after changing sys.path *should* take into account the change, not to mention any changes to meta_path, path hooks, etc. (And it's how reload() worked before importlib.) I suppose it's not really documented all that well, but way way back in the 2.3 timeframe I asked for a tweak to PEP 302 to make sure that reload() (in the re-find sense) would work properly with PEP 302 loaders like zipimport -- some of the language still in the PEP is there specifically to support this use case. (Specifically, the bit that says loaders *must* use the existing module object in sys.modules if there's one there already, so that reload() will work. It was actually in part to ensure that reload() would work in the case of a re-find.) It appears that since then, the PEP has been changed in a way that invalidates part of the purpose of the prior change; I guess I missed the discussion of that change last year. :-( ISTM there should've been such a discussion, since IIRC importlib wasn't supposed to change any Python semantics, and this is a non-trivial change to the semantics of reload() even in cases that aren't doing lazy imports or other such munging. reload() used to take sys.* and __path__ changes into account, and IMO should continue to do so. If this is an intentional change in reload() semantics, other Python implementations need to know about this too! (That being said, I'm not saying I shouldn't or couldn't have tested this in 3.3 and found out about it that way. And the existence of issue18698 suggests that nobody's relying yet on even the *fundamental* semantics of PEP 302 reload() working properly in 3.3, since that was an even bigger change that nobody spotted till a couple of months ago.) _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
