[Python-ideas] for/else syntax

[Gerald Britton]

Yes, you need to have some early exit in the body of the loop.
Anyway, it's just a toy example.  Not too hard to come with better
ones.

On Sat, Oct 3, 2009 at 11:31 AM, Masklinn <masklinn at masklinn.net> wrote:
> On 3 Oct 2009, at 13:49 , Gerald Britton wrote:
>>
>> Sory Carl, I did NOT get it dead wrong.  The else is executed if the
>> for loop falls through.  That's the whole idea.  Probably I should
>> have set i to -1 in the else clause of the toy example though:
>>
>> for i, j in enumerate(something):
>>  # do something
>>  i += 1
>> else:
>> i = -1
>>
>> if i > 0:
>>  # we did something
>>
>> If you don't think the else is executed when the for-loop falls
>> through, then you should re-read the documentation, here:
>
> Carl didn't dispute that point. In fact that's exactly the issue with your
> code: since you don't have any `break` statement in your `for:` loop, the
> `else:` clause will *always* be executed, whether `something` is an empty
> collection or not.
>
> Thus, the following `if i > 0:` clause cannot under any circumstance be
> executed.
>
> Your code (unless there is a break in the 'do something' part) is equivalent
> to:
>
>    for i, j in enumerate(something):
>        # do something
>        i += 1
>    i = -1
>
>    if i > 0:
>        # can never happen
>



-- 
Gerald Britton