Behavior of the for-else construct

[Jon Ribbens]

On 2022-03-03, computermaster360 <computermaster360 at gmail.com> wrote:
> Do you find the for-else construct useful? Have you used it in
> practice?

Yes, I use it frequently.

> I have used it maybe once. My issue with this construct is that
> calling the second block `else` doesn't make sense; a much more
> sensible name would be `then`.

You are not the only person with this opinion, although personally
I have the opposite opinion. I think of 'for...else' as being
a search for something that matches a condition, and the 'else'
block is if no item is found that matches. If you think of it like
that, the syntax makes perfect sense.

> Now, imagine a parallel universe, where the for-else construct would
> have a different behavior:
>
>     for elem in iterable:
>         process(elem)
>     else:
>         # executed only when the iterable was initially empty
>         print('Nothing to process')
>
> Wouldn't this be more natural? I think so. Also, I face this case much
> more often than having detect whether I broke out of a loop early
> (which is what the current for-else construct is for).

I guess peoples' needs vary. I can't even remember the last time
I've needed something as you suggest above - certainly far less
often than I need 'for...else' as it is now.

> What are your thoughts? Do you agree?

I don't agree. But it doesn't really matter if anyone agrees or not,
since there is no chance whatsoever that a valid Python syntax is
suddenly going to change to mean something completely different, not
even in "Python 4000" or whatever far-future version we might imagine.

This exact topic was discussd in November 2017 by the way, under the
subject heading "Re: replacing `else` with `then` in `for` and `try`".
I'm not sure any particular conclusion was reached though except that
some people think 'else' is more intuitive and some people think
'then' would be more intuitive.