for / while else doesn't make sense

Sat May 21 00:01:52 EDT 2016

On Sat, May 21, 2016 at 1:50 PM, Steven D'Aprano <steve at pearwood.info> wrote:
> On 2016年5月21日 10:24 am, Jon Ribbens wrote:
>>> On 2016年05月20日, Ethan Furman <ethan at stoneleaf.us> wrote:
>>>> If you don't take the extra step of _break_ it is the usual case.
>>>> Having an "for: else:" clause without a "break" would be so unusual
>> that it's literally nonexistent, because it would always be a bug.
>> So no, it isn't the usual case for "for: else:".
>>> What do you mean? A for...else without a break is perfectly legal code, and
> does *EXACTLY* what it is documented as doing:
>> - first the "for" block runs, looping as appropriate;
> - THEN the "else" block runs, *once*.
>> How is this "always a bug"?
>> Would you classify the second line here:
>> print("Hello World!")
> pass
>>> as a bug? What exactly would your bug report be? "pass statement does
> nothing, as expected. It should do nothing. Please fix."
>
Yes, I would. It's not a bug in Python or CPython - it's a bug in the
second line of code there. It implies something that isn't the case.
It's like having this code:
if True:
 pass
elif False:
 pass
else:
 assert True
It's well-defined code. You know exactly what Python should do. But is
it good code, or is it the sort of thing that gets posted here:
http://thedailywtf.com/articles/a-spiritual-journey
ChrisA