Section 6.11. List Selections

6.11. List Selections

Use grep and first instead of for when searching for values in a list.

The same principles apply when you want to refine a list by removing unwanted elements. Instead of a for loop:

          # Identify candidates who are unfit for the cut-and-thrust of politics...     my @disqualified_candidates;     for my $name (@candidates) {         if (cannot_tell_a_lie($name)) {             push @disqualified_candidates, $name;         }     }

just use a grep:

      
     # Identify candidates who are unfit for the cut-and-thrust of politics...
     my @disqualified_candidates         = grep {cannot_tell_a_lie($_)} @candidates;

Likewise, don't use a for when you're searching a list for a particular element:

          # Victimize someone at random...     my $scapegoat = $disqualified_candidates[rand @disqualified_candidates];     # Unless there's a juicier story...     SEARCH:     for my $name (@disqualified_candidates) {         if (chopped_down_cherry_tree($name)) {             $scapegoat = $name;             last SEARCH;         }     }     # Publish and be-damn...     print {$headline} "Disgraced $scapegoat Disqualified From Election!!!\n";

Using the first function often results in code that is both more comprehensible and more efficient:

      use List::Util qw( first );     
# Find a juicy story...
     my $scapegoat         = first { chopped_down_cherry_tree($_) }  @disqualified_candidates;     
# Otherwise victimize someone at random...
     if (!defined $scapegoat) {         $scapegoat = $disqualified_candidates[rand @disqualified_candidates];     }     
# Publish and be-damn...
     print {$headline} "Disgraced $scapegoat Disqualified From Election!!!\n";