for -- else: what was the motivation?

[Axy]

On 10/10/2022 15:52, Weatherby,Gerard wrote:
> Core developer Raymond Hettinger explains the history starting at 15:40 https://www.youtube.com/watch?v=OSGv2VnC0go
>
> (which I found on stackoverflow https://stackoverflow.com/questions/9979970/why-does-python-use-else-after-for-and-while-loops )
>
> TL:DR
> The “else” is a historical artificial from the way developers thought during the transition from unstructured (i.e. “GOTO”) programming to structured programming. Since we all do structured now, it seems odd.
>
>
> From: Python-list <python-list-bounces+gweatherby=uchc.edu at python.org> on behalf of Calvin Spealman <cspealma at redhat.com>
> Date: Monday, October 10, 2022 at 10:38 AM
> To: python-list at python.org <python-list at python.org>
> Subject: Re: for -- else: what was the motivation?
> *** Attention: This is an external email. Use caution responding, opening attachments or clicking on links. ***
>
> On Sat, Oct 8, 2022 at 5:35 PM rbowman <bowman at montana.com> wrote:
>
>> On 10/7/22 21:32, Axy wrote:
>>> So, seriously, why they needed else if the following pieces produce same
>>> result? Does anyone know or remember their motivation?
>> In real scenarios there would be more logic in the for block that would
>> meet a condition and break out of the loop. If the condition is never
>> met, the else block runs. To steal from w3schools:
>>
>>
>> fruits = ["apple", "peach", "cherry"]
>> for x in fruits:
>>     print(x)
>>     if x == "banana":
>>       break
>> else:
>>     print("Yes we got no bananas")
>>
> I wonder if for/else could have been less confusing if it was referred to
> as for-break-else and if the else clause was only valid syntax if the for
> loop actually contained a break statement in the first place.

Sounds reasonable. It would be something alike UnboundLocalError when a 
local variable referenced before assignment. If they won't remove "else" 
completely in far future, that checking really worths implementing now.

Excellent stackoverflow link, thanks!

Axy.