any() and all() on empty list?

Ron Adam rrr at ronadam.com
Fri Mar 31 21:00:33 CEST 2006


Carl Banks wrote:
> Ron Adam wrote:
>> Carl Banks wrote:
>>
>>> In Python, yes and no are the only possible answers.  Probably the only
>>> analogous thing you could do in Python would be for all() to raise
>>> ValueError when passed an empty sequence.
>> There is also 'None' which serves a similar purpose of indicating an
>> invalid value when passing arguments.
> 
> If all() were to return None, then if would essentially be like
> returning False, because an if-statement would treat False and None the
> same (as would most anything else expecting a boolean value).
> 
> The only reasonable way to say "false assumption" in Python is to raise
> an exception.
> 
> 
> Carl Banks

Then maybe None should be evaluated as True so it is consistent with 
all().   ;-)


Not serious of course,  Cheers,
    Ron










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