A Python 3000 Question

[George Sakkis]

On Oct 31, 8:44 am, Neil Cerutti <horp... at yahoo.com> wrote:
> On 2007-10-30, George Sakkis <george.sak... at gmail.com> wrote:
>
>
>
> > On Oct 30, 11:25 am, Neil Cerutti <horp... at yahoo.com> wrote:
> >> On 2007-10-30, Eduardo O. Padoan <eduardo.pad... at gmail.com> wrote:
>
> >> > This is a FAQ:
> >> >http://effbot.org/pyfaq/why-does-python-use-methods-for-some-function...
>
> >> Holy Airy Persiflage Batman!
>
> >> Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bit (Intel)] on
> >> win32
> >> Type "help", "copyright", "credits" or "license" for more information.>>> import timeit
> >> >>> timeit.Timer('len(seq)', 'seq = range(100)').timeit()
> >> 0.20332271187463391
> >> >>> timeit.Timer('seq.__len__()', 'seq = range(100)').timeit()
>
> >> 0.48545737364457864
>
> > Common mistake; try this instead:
>
> > timeit.Timer('seqlen()',
> >              'seq = range(100); seqlen=seq.__len__').timeit()
>
> Why would I want to do that?


To realize that __len__ is actually faster than len in this case; your
second timing is dominated by the time to do attribute lookup.


George