http://www.perlmonks.org?node_id=1034383


in reply to Comparing spaceships (cmp and <=> as options)

Here is a version that uses a variant of the Schwartzian Transform. 

my @records = (
   [10, 'xyz232', 'secret project'],
   [ 5, 'foo123', 'world domination'],
   [ 7, 'bar666', 'have a beer'],
);

my %sort_this_way = ( 
    'hours' => 
        [0, sub { return sort { $a->[0][$a->[1]]  
                                    <=> $b->[0][$b->[1]]; } @_; }],
    'code'  => 
        [1, sub { return sort { $a->[0][$a->[1]] 
                                    cmp $b->[0][$b->[1]]; } @_; }],
    'name'  => 
        [2, sub { return sort { $a->[0][$a->[1]] 
                                    cmp $b->[0][$b->[1]]; } @_; }],
);

my $sort = 'hours'; # really comes from a switch

my @new = map  { $_->[0] }
          $sort_this_way{$sort}->[1](
          map  { [ $_ ,
                   $sort_this_way{$sort}->[0],
                   $_->[ $sort_this_way{$sort}->[0] ] ] } @records );

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Granted the sort part of the transform is actually a function call but I couldn't remember how to set up a function to not require parenthesis without defining a prototype first.


PJ
use strict; use warnings; use diagnostics;

In Section Seekers of Perl Wisdom