On Tue, 2005-12-06 at 19:58 -0500, Raymond Hettinger wrote:
> Any real-world use cases or compelling contrived examples?
>
> ISTM, that the code calling it.stop() would already be in position to
> break-out of the iteration directly or set a termination flag. Instead
> of:
>
> it = itertools.interruptable(iterable):
> for x in it:
> . . .
> if cond(x):
> it.stop()
>
> Why not write:
>
> for x in iterable:
> . . .
> if cond(x):
> break
>
> If needed, the for-loop can have an else-clause for any processing
> needed in the event of interruption.
The idea was motivated by a case of nested loops, similar to:
for x in iterable1:
for y in iterable2:
for z in iterable3:
. . .
if cond1(x):
iterable1.stop()
if cond2(y):
iterable2.stop()
if cond3(z):
iterable3.stop()
. . .
It seemed more convenient at the time than having to deal with multiple
termination flags, or breaks, or a combination thereof.
The ability to remotely terminate a for-loop also struck me as somewhat
interesting:
def estimate(item, iterable):
. . .
if good_enough:
iterable.stop()
return result
for x in iterable:
. . .
approx *= estimate(x, iterable)
But these are highly contrived and hardly compelling.
I was primarily interested in whether anyone recalls discussing the
ability to prematurely terminate an iterator and whether there are any
technical drawbacks other than it being redundant.
Matthew Barnes
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