"Steve R. Hastings" <[EMAIL PROTECTED]> writes:
> So, Python 2.5 will have new any() and all() functions.
> http://www.python.org/dev/peps/pep-0356/
And there was much rejoicing.
> any(seq) returns True if any value in seq evaluates true, False otherwise.
Yep.
> all(seq) returns True if all values in seq evaluate true, False otherwise.
Not quite how I'd phrase it. I prefer, for symmetry with 'any':
all(seq) returns False if any value in seq evaluates false, True otherwise.
> I have a question: what should these functions return when seq is an
> empty list?
>
>
>
> Here is Guido's original article where he suggested any() and all():
> http://www.artima.com/weblogs/viewpost.jsp?thread=98196
>
> He offered this sample code for the semantics of any() and all():
>
> def any(S):
> for x in S:
> if x:
> return True
> return False
>
> def all(S):
> for x in S:
> if not x:
> return False
> return True
I love the symmetry of these semantics, find them quite intuitive, and
therefore disagree with your interpretation of 'all()'.
> I'm completely on board with the semantics for any(). But all() bothers
> me. If all() receives an empty list, it will return True, and I don't
> like that. To me, all() should be a more restrictive function than any(),
> and it bothers me to see a case where any() returns False but all()
> returns True.
-1.
You may as well argue that "any() should be a more restrictive
function than all(), and it bothers me to see a case where all()
returns False but any() returns True."
It seems clear to me that an empty argument list fails a check for
"any True?", because that's the same as a check for "all False?". The
only reasonable alternative would be a special case for an empty
argument list, and that's too ugly.
It seems clear to me that an empty argument list passes a check for
"all True?", because that's the same as a check for "any False?". The
only reasonable alternative would be a special case for an empty
argument list, and that's too ugly.
To imagine that one of these "should be a more restrictive function"
would belie their simple, elegant, and (to me) obvious definitions. I
disagree with your interpretation.
--
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`\ the neighborhood kids I lift it over my head and tell them to |
_o__) get out of my yard or I'll throw it at them." -- Steven Wright |
Ben Finney
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