Bugs item #1542308, was opened at 2006-08-17 18:56 Message generated for change (Comment added) made by etrepum You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1542308&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Interpreter Core Group: Python 2.5 Status: Open Resolution: None Priority: 8 Submitted By: Bob Ippolito (etrepum) Assigned to: Nobody/Anonymous (nobody) Summary: Nested finally in generators don't follow PEP 342 Initial Comment: The close() and GC interaction of generators that use yield inside of finally blocks doesn't execute correctly when nested. See the attached example. More information about the issue is in the Mozilla bug tracker (they found a similar bug in their implementation for JS 1.7): https://bugzilla.mozilla.org/show_bug.cgi?id=349012 ---------------------------------------------------------------------- >Comment By: Bob Ippolito (etrepum) Date: 2006-08-22 17:00 Message: Logged In: YES user_id=139309 Uh no, that wouldn't reach an infinite loop because any attempt to yield during close will raise RuntimeError and terminate the loop. The problem is that finally doesn't execute. Finally clauses always must execute. If they don't, then they're worthless. The real strange issue is that if close is called, then GC makes a second attempt, and it *does* execute the outer finally clause. There are definitely bugs here. ---------------------------------------------------------------------- Comment By: Guido van Rossum (gvanrossum) Date: 2006-08-22 16:47 Message: Logged In: YES user_id=6380 I lost my patience halfway through reading the Mozilla bug tracker, but IMO this works as designed. The philosophical question is, would you rather see the outer finally clause reached in your example, or would you rather see the following generator terminated upon close? (If you "fix" the former, the latter ends up in an infinite loop when you attempt to close() or GC it.) def gen(): while True: try: yield except: pass ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1542308&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
