Re: [Omaha.pm] Sort quickie

[Jay Hannah <jay@jays.net>]

On Jul 14, 2004, at 10:32 PM, Hugh Jarce wrote:
> This sub can be written more efficiently as:
>   sub by_date2 { substr($a,4) cmp substr($b,4) || $a cmp $b }
> or:
>   sub by_date3 { substr($a,4).$a cmp substr($b,4).$b }

Wow. Very slick.

> Out of curiosity, I benchmarked 4 different ways to do it:
>  
> use strict;
> use Benchmark;

-ponder-  I need to study Benchmark. Looks cool. What's the point of 
@x? Can

   sub j9 { my @x = sort by_date @dates }

be written as

   sub j9 { sort by_date @dates }

?

> sub j1 {
>     my @x = map { substr($_,4) } sort map { substr($_,4).$_ } @dates
> }

-laugh-  Took me 3 minutes to figure out what that does. map tends to 
confuse my limited synapses.

> Which surprised me. I expected j1 to be much faster.

Usually its faster for me to re-write a use of map than it is for me to 
figure out what I was doing when I wrote it. -grin- Typically I can't 
grok map at a glance, which slows me down. Can't argue w/ fast 
benchmarking though!

Thanks for the tips!

j