[Python-ideas] for/else statements considered harmful
Guido van Rossum
guido at python.org
Thu Jun 7 18:57:00 CEST 2012
On Thu, Jun 7, 2012 at 9:45 AM, MRAB <python at mrabarnett.plus.com> wrote:
> 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
>>> pass # fell through
>>> 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
>> 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
You can stop right there. This design is not going anywhere.
--Guido van Rossum (python.org/~guido)
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