[Omaha.pm] return from sub: array vs. arrayref

["Jay Hannah" <jhannah@omnihotels.com>]

The ? was posed to me: Why would you ever return a single array ref from a sub? Why not just return an array?

One possible argument is efficiency/speed: arrayrefs can be faster if you have huge (or huge number of) arrays you're returning. Save Perl one forced copy/clear of an array.

j


j.pl:
---
use Benchmark qw(:all) ;

timethese(100000, {
  'array'    => 'loop_array()',
  'arrayref' => 'loop_arrayref()'
});



sub loop_array {
   my @a = return_array();
   foreach (@a) { $_; }
}

sub return_array {
   @ret = 1..100;
   return @ret;
}

sub loop_arrayref {
   my $a = return_arrayref();
   foreach (@$a) { $_; }
}

sub return_arrayref {
   @ret = 1..100;
   return \@ret;
}
---

$ perl j.pl
Benchmark: timing 100000 iterations of array, arrayref...
     array:  8 wallclock secs ( 8.28 usr +  0.00 sys =  8.28 CPU) @ 12077.29/s (n=100000)
  arrayref:  3 wallclock secs ( 4.83 usr +  0.00 sys =  4.83 CPU) @ 20703.93/s (n=100000)