for...else
Peter Otten
__peter__ at web.de
Tue Jun 2 08:27:35 EDT 2015
acdr wrote:
> Hi,
>
> Currently, in various places in my code, I have the equivalent of:
>
> for x in it:
> if complicated_calculation_1():
> cleanup()
> break
> complicated_calculation_2()
> if complicated_calculation_3():
> cleanup()
> break
>
> Obviously, I'm repeating myself by having two separate calls to
> cleanup(). I can't really see a nicer way to do this. (Though I see
> plenty of non-nice ways to do this, such as adding "broken = True" in
> front of every "break", and then after the loop is done, have an "if
> broken" section.) Other solutions that I'm not particularly fond of
> can be found on stackexchange, where someone else is trying to do the
> same thing:
> http://stackoverflow.com/questions/3296044/opposite-of-python-for-else
Perhaps you like of these:
for x in it:
if not complicated_calculation_1():
complicated_calculation_2()
if not complicated_calculation_3():
continue
cleanup()
break
def f():
for x in it:
if complicated_calculation_1():
break
complicated_calculation_2()
if complicated_calculation_3():
break
else:
return
cleanup()
> I'm wondering if there is a demand for expanding the "for...else"
> functionality to be expanded also have a block of code that only gets
> called if the loop is broken out of. I.e.:
>
> for x in it:
> ...
> then:
> # "break" was called
> ...
> else:
> # "break was not called
> ...
You may not like using a flag, but it's a really obvious approach and the
situations where it's necessary are not very common. Apart from indentation-
based blocks Python is very middle-of-the-road, so I'd ask if there is an
existing language that has such a feature, and if yes, is it used
frequently? I suspect that there are many Python programmers that have never
even used (for...else).
Python the language is already becoming too complicated for my taste; I
would rather not add more constructs where there is no significant
advantage.
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