Greg Ewing wrote:
> Ron Adam wrote:
>> There seems to be some confusion as to weather or
>> not 'for's will do finalizing. So I was trying to stress I think
>> regular 'for' loops should not finalize. They should probably give an
>> error if an object with an try-finally in them or an __exit__ method.
>
> But if the for-loop can tell whether the iterator
> needs finalizing or not, why not have it finalize
> the ones that need it and not finalize the ones
> that don't? That would be backwards compatible,
> since old for-loops working on old iterators would
> work as before.
That's why I suggested to have the behaviour depend on what is passed
in as EXPR.
for VAR in EXPR:
BLOCK
could be translated to:
__cleanup = False
__itr = EXPR
if not isinstance(__itr,iterator):
__itr = iter(__itr)
__cleanup = True
while True:
try:
VAR = __itr.next()
except StopIteration:
break
BLOCK
if __cleanup:
__itr.__exit__()
Which would require isinstance(__itr,iterator) or equivalent to act as
a robust test on iterators.
I'll leave 'for' with an 'else' clause as an exercise to the reader.
--eric
_______________________________________________
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
