Jim Jewett wrote:
> Why not just agressively run the finalization on both forms when the
> reference count permits?
So the iterator is always finalised if the for loop has the only reference?
Two problems I can see there is that naming the target of the for loop would
prevent it being finalised, and that this would make life interesting when the
Jython or IronPython folks catch up to Python 2.5. . .
The finalised/not finalised aspect definitely seems to be the key behavioural
distinction between the two forms, though. And I think there are legitimate use
cases for a non-finalised form. Things like:
for line in f:
if end_of_header(line):
break
# process header line
for line in f:
# process body line
With only a finalised form of iteration available, this would need to be
rewritten as something like:
def header(f):
line = next(f)
while not end_of_header(line):
line = next(f, yield line)
for line in header(f):
# process header line
for line in f:
# process body line
Considering the above, I actually have grave reservations about *ever* making
finalisation the default behaviour of for loops - if I break out of a standard
for loop before exhausting the iterator, I would expect to be able to resume the
iterator afterwards, rather than having it flushed behind my back.
Cheers,
Nick.
--
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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