Blog "about python 3"

[Steven D'Aprano]

Roy Smith 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.

I know somebody who was once touring in the States, and ended up travelling
cross-country by road with the roadies rather than flying. She tells me of
the time someone pointed out that they were travelling in the wrong
direction, away from their destination. The roadie driving replied "Who
cares? We're making fantastic time!"

(Ah, the seventies. So many drugs...)

Fast is never more important than correct. It's just that sometimes you
might compromise a little (or a lot) on what counts as correct in order for
some speed.

To give an example, say you want to solve the Travelling Salesman Problem,
and find the shortest path through a whole lot of cities A, B, C, ..., Z.
That's a Hard Problem, expensive to solve correctly.

But if you loosen the requirements so that a correct solution no longer has
to be the absolutely shortest path, and instead accept solutions which are
nearly always close to the shortest (but without any guarantee of how
close), then you can make the problem considerably easier to solve.

But regardless of how fast your path-finder algorithm might become, you're
unlikely to be satisfied with a solution that travels around in a circle
from A to B a million times then shoots off straight to Z without passing
through any of the other cities.



-- 
Steven