empty clause of for loops

[Sven R. Kunze]

On 16.03.2016 11:47, Peter Otten wrote:
>
> What would you expect?

A keyword filling the missing functionality? Some Python magic, I 
haven't seen before. ;-)

>
>>>> class Empty(Exception): pass
> ...
>>>> def check_empty(items):
> ...     items = iter(items)
> ...     try:
> ...         yield next(items)
> ...     except StopIteration:
> ...         raise Empty
> ...     yield from items
> ...
>>>> try:
> ...    for item in check_empty("abc"): print(item)
> ... except Empty: print("oops")
> ...
> a
> b
> c
>>>> try:
> ...    for item in check_empty(""): print(item)
> ... except Empty: print("oops")
> ...
> oops

He will be highly delighted so see such a simplistic solution. ;-)

> I'm kidding, of course. Keep it simple and use a flag like you would in any
> other language:
>
> empty = True:
> for item in items:
>      empty = False
>      ...
> if empty:
>      ...
>

He likes this approach. Thanks. :-)


Although, I for one would like a keyword. I remember having this issue 
myself, and found that the "empty" variable approach is more like a 
pattern. As usual, patterns are workarounds for features that a language 
misses.

Best,
Sven