The Cost of Dynamism (was Re: Pyhon 2.x or 3.x, which is faster?)
Steven D'Aprano
steve at pearwood.info
Mon Mar 14 19:24:43 EDT 2016
On Mon, 14 Mar 2016 06:39 am, BartC wrote:
> class switch(object):
> value = None
> def __new__(class_, value):
> class_.value = value
> return True
>
> def case(*args):
> return any((arg == switch.value for arg in args))
That's quite a clever use of a class. By clever, I mean imaginative, not
necessarily smart.
> I used it in my benchmark to replace the if-else chain checking three
> lots of ranges:
>
> switch(c)
> if case(ord("A"),ord("B"),ord("C"),ord("D"),ord("E"),ord("F"),
> ord("G"),ord("H"),ord("I"),ord("J"),ord("K"),ord("L"),
> ord("M"),ord("N"),ord("O"),ord("P"),ord("Q"),ord("R"),
> ord("S"),ord("T"),ord("U"),ord("V"),ord("W"),ord("X"),
> ord("Y"),ord("Z")):
> upper+=1
> elif case(ord("a"),ord("b"),ord("c"),ord("d"),ord("e"),ord("f"),
> ord("g"),ord("h"),ord("i"),ord("j"),ord("k"),ord("l"),
> ord("m"),ord("n"),ord("o"),ord("p"),ord("q"),ord("r"),
> ord("s"),ord("t"),ord("u"),ord("v"),ord("w"),ord("x"),
> ord("y"),ord("z")):
> lower+=1
> elif case(ord("0"),ord("1"),ord("2"),ord("3"),ord("4"),ord("5"),
> ord("6"),ord("7"),ord("8"),ord("9")):
> digits+=1
> else:
> other+=1
Ai-ai-ai-aiye!
What a mess! See what happens when you write assembly language in
Python? :-)
Try this instead:
c = chr(c)
if 'A' <= c <= 'Z':
upper += 1
elif 'a' <= c <= 'z':
lower += 1
elif '0' <= c <= '9':
digits += 1
else:
other += 1
But even better:
if c.isupper():
upper += 1
elif c islower():
lower += 1
elif c.isdigit():
digits += 1
else:
other += 1
which will work correctly for non-ASCII characters as well.
--
Steven
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