On Apr 22, 2005, at 12:28 AM, Brett C. wrote:
Bob Ippolito wrote:
On Apr 21, 2005, at 8:59 PM, Josiah Carlson wrote:
Guido van Rossum <[EMAIL PROTECTED]> wrote:
[Brett]
I think I agree with Samuele that it would be more pertinent to put all of this effort into trying to come up with some way to handle cleanup in a generator.
I.e. PEP 325.
But (as I explained, and you agree) that still doesn't render PEP 310
unnecessary, because abusing the for-loop for implied cleanup
semantics is ugly and expensive, and would change generator semantics;
and it bugs me that the finally clause's reachability depends on the
destructor executing.
Yes and no. PEP 325 offers a method to generators that handles cleanup
if necessary and calls it close(). Obviously calling it close is a
mistake. Actually, calling it anything is a mistake, and trying to
combine try/finally handling in generators with __exit__/close (inside
or outside of generators) is also a mistake.
Start by saying, "If a non-finalized generator is garbage collected, it
will be finalized." Whether this be by an exception or forcing a return,
so be it.
If this were to happen, we have generator finalization handled by the
garbage collector, and don't need to translate /any/ for loop. As long
as the garbage collection requirement is documented, we are covered
(yay!).
Well, for the CPython implementation, couldn't you get away with using garbage collection to do everything? Maybe I'm missing something..
[SNIP]
Well, if you are missing something then so am I since your suggestion is
basically correct. The only issue is that people will want more immediate
execution of the cleanup code which gc cannot guarantee. That's why the
ability to call a method with the PEP 325 approach gets rid of that worry.
Well in CPython, if you are never assigning the generator to any local or global, then you should be guaranteed that it gets cleaned up at the right time unless it's alive in a traceback somewhere (maybe you WANT it to be!) or some insane trace hook keeps too many references to frames around..
It seems *reasonably* certain that for reasonable uses this solution WILL clean it up optimistically.
-bob
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