[Python-ideas] Control Flow - Never Executed Loop Body

[Vito De Tullio]

Chris Angelico wrote:

>>     item = _sentinel = object()
>>     for item in iterable:
>>         # do for each item
>>     if item is _sentinel:
>>         # do exactly when iterable raises StopIteration on the first pass
> 
> What if 'iterable' is locals().values()? Can you, with perfect
> reliability, recognize that case? AIUI this is exactly why next() and
> __next__() are defined to "return a value or raise", rather than
> "return a value or return a magic no-more-values value", because
> there's always the possibility that the no-more-values value is a
> legitimately-yielded value.

so, the "correct" way to handle this is something like

    try:
        e = next(iterable)
    except StopIteration:
        empty_suite()	# there is no element
    else:
        main_suite(e)	# handle the first element
        for e in iterable:
            main_suite(e)	# handle the rest of the elements

?

apart for the readability you need to "copy" the same code two times (or 
refactor in a function)


-- 
By ZeD