Greg Ewing wrote:
I'm inclined to think this situation is a symptom that the idea of being able to catch GeneratorExit at all is flawed. If generator finalization were implemented by means of a forced return, or something equally uncatchable, instead of an exception, we wouldn't have so much of a problem.
Well, in theory people are meant to be writing "except Exception:" rather than using a bare except or catching BaseException - that's a big part of the reason SystemExit, KeyboardInterrupt and GeneratorExit *aren't* Exception subclasses.
Related to that, I'm starting to come back to my original instinct that GeneratorExit should not be thrown into the subiterator at all. Rather, it should be taken as an indication that the delegating generator is being finalized, and the subiterator's close() method called if it has one. Then there's never any question about whether to re-raise it -- we should always do so.
I think that's a simpler finalisation rule to remember, so I'd be fine with that approach. I don't think we're going to be able to completely eliminate the tricky subtleties from this expression, but we can at least try to keep them as simple as possible. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia ---------------------------------------------------------------