[Guido] > >uncertainty of the possibility to call close() from the > >destructor may have slowed that down.
[Phillip] > If you're talking about the bit about __del__ not working when hanging off > a cycle, my apologies for creating that confusion, I misunderstood Tim's post. No, I'm not talking about that. > If you're talking about the circular reference scenario involving > exceptions, then I think I've already given a tentative explanation why > such a cycle will not include the generator-iterator itself (only its > frame) as long as the generator-iterator clears its frame's f_back when the > frame is not in use. It would probably be a good idea to verify this, but > I think the basic idea is sound. Yes, the generator does clear its f_back when it's suspended. > The only scenario in which a generator-iterator would be uncollectable is > if you took some action outside the iterator to pass it into itself, or if > you stored the iterator in a global variable. However, even in the latter > case, the phase of Python shutdown that clears module contents would break > the cycle and cause the generator to finalize, albeit a bit late and > perhaps in a broken way. Still, storage of generator-iterators in module > globals is a very unlikely scenario, since it's more common to loop over > such iterators than it is to store them in any kind of variable. Sure. But I still have some reservations, since cycles can pop up in the strangest of places (especially when tracebacks are involved -- tracebacks have been causing problems due to cycles and keeping variables alive almost since Python's inception). I posted about this a while ago, but don't recall seeing a response that took my fear away. Unfortunately, discussing this is about 1000x easier when you have a shared drawing surface available -- I cannot even think about this myself without making drawings of object references... -- --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
