empty clause of for loops

[Sven R. Kunze]

On 16.03.2016 14:09, Tim Chase wrote:
> If you can len() on it, then the obvious way is
>
>    if my_iterable:
>      for x in my_iterable:
>        do_something(x)
>    else:
>      something_else()
>
> However, based on your follow-up that it's an exhaustible iterator
> rather than something you can len(), I'd use enumerate:
>
>    count = 0 # have to set a default since it doesn't get assigned
>              # if no iteration happens
>    for count, x in enumerate(my_iterable, 1):
>      do_something(x)
>    if not count:
>      something_else()

Interesting variation. Good to keep in mind if I encounter a situation 
where I need both (empty flag + counter). Thanks. :)

> I do a lot of ETL work, and my code often has to report how many
> things were processed, so having that count is useful to me.
> Otherwise, I'd use a flag:
>
>    empty = True
>    for x in my_iterable:
>      empty = False
>      do_something(x)
>    if empty:
>      something_else()

Best,
Sven