On Fri, Aug 6, 2021 at 5:31 PM <wyz2...@163.com> wrote:
>
> Before the introduction of bool and also in other languages, `not not x`
> was/is used to convert to True (1) and False (0). However, the old way is
> still much faster than bool(x) or even operator.truth(x).
> Test:
> > py -3.10 -m timeit -s "objects = 1, 0, -0.0, "20", "False", 93, 28.569, [],
> > set(), {1: 5}" "[(not not x) for x in objects]"
> 200000 loops, best of 5: 1.12 usec per loop
> > py -3.10 -m timeit -s "objects = 1, 0, -0.0, "20", "False", 93, 28.569, [],
> > set(), {1: 5}" "[(bool(x)) for x in objects]"
> 200000 loops, best of 5: 2.32 usec per loop
> > py -3.10 -m timeit -s "from operator import truth; objects = 1, 0, -0.0,
> > "20", "False", 93, 28.569, [], set(), {1: 5}" "[(truth(x)) for x in
> > objects]"
> 200000 loops, best of 5: 2.04 usec per loop
> > py -3.10 -V
> Python 3.10.0rc1
>
> That's nearly 52%/46% faster! I guess the name lookup and the FUNCTION_CALL
> is slower than UNARY_NOT. So actually, using `not not` is an optimize,
> although it isn't clear. This is interesting.
>
Interesting perhaps, but not really surprising. Name lookups and
function calls aren't as fast as operators. But why is this on
python-ideas?
ChrisA
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/OAAIKIR52GTDTOY7QGXDGQY7APO5D53K/
Code of Conduct: http://python.org/psf/codeofconduct/
