[Python-ideas] for/else statements considered harmful

MRAB python at mrabarnett.plus.com
Thu Jun 7 18:45:22 CEST 2012

On 07/06/2012 17:32, MRAB wrote:
> On 07/06/2012 16:52, Alice Bevan–McGregor wrote:
>>  On 2012-06-07 15:30:11 +0000, Mike Meyer said:
>>>   Calling it "wrap-up processing" seems likely to cause people to think
>>>   about it as meaning "finally". But if the else clause is not executed
>>>   if the except clause is (as done by try/except/else), then there's no
>>>   longer an easy way to describe it.
>>>   It seems like adding an except would change the conditions under which
>>>   the else clause is executed (unlike try/except/else), as otherwise
>>>   there's no easy way capture the current behavior, where else is
>>>   executed whenever there are no chunks left to process. But that kind
>>>   of things seems like a way to introduce bugs.
>>  Well, how about:
>>       for<var>   in<iterable>:
>>           pass # process each<var>
>>       except:  # no arguments!
>>           pass # nothing to process
>>       else:
>>           pass # fell through
>>       finally:
>>           pass # regardless of break/fallthrough/empty
>>  Now for loops perfectly match try/except/else/finally!>:D  (Like
>>  exception handling, finally would be called even with an inner return
>>  from any of the prior sections.)
> Is the "finally" clause really necessary? Is it just the same as putting it
> after the loop?
I've just noticed your remark about the finally clause being run even
if there's a return. I can't say I like that; that's the job of

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