Blog "about python 3"

[Chris Angelico]

On Sun, Jan 5, 2014 at 12:55 AM, Roy Smith <roy at panix.com> wrote:
> In article <mailman.4882.1388808283.18130.python-list at python.org>,
>  Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
>
>> Surely everybody prefers fast but incorrect code in
>> preference to something that is correct but slow?
>
> I realize I'm taking this statement out of context, but yes, sometimes
> fast is more important than correct.  Sometimes the other way around.

More usually, it's sometimes better to be really fast and mostly
correct than really really slow and entirely correct. That's why we
use IEEE floating point instead of Decimal most of the time. Though
I'm glad that Python 3 now deems the default int type to be capable of
representing arbitrary integers (instead of dropping out to a separate
long type as Py2 did), I think it's possibly worth optimizing small
integers to machine words - but mainly, the int type focuses on
correctness above performance, because the cost is low compared to the
benefit. With float, the cost of arbitrary precision is extremely
high, and the benefit much lower.

With Unicode, the cost of perfect support is normally seen to be a
doubling of internal memory usage (UTF-16 vs UCS-4). Pike and Python
decided that the cost could, instead, be a tiny measure of complexity
and actually *less* memory usage (compared to UTF-16, when lots of
identifiers are ASCII). It's a system that works only when strings are
immutable, but works beautifully there. Fortunately Pike doesn't have
any, and Python has only one, idiot like jmf who completely
misunderstands what's going on and uses microbenchmarks to prove
obscure points... and then uses nonsense to try to prove... uhh...
actually I'm not even sure what, sometimes. I wouldn't dare try to
read his posts except that my mind's already in a rather broken state,
as a combination of programming and Alice in Wonderland.

ChrisA