Since you've already got ascending/descending options, passing in $a and $b seems redundant.
The options could be simplified by mimicking the regex flags e.g. assuming case sensitivity as the default i.e. 'i' meaning case insensitive and no 'i' meaning case sensitive. And also leaving out the hyphens.
It could be expanded by proving alternate equivalent options so you don't have to remember the order of them e.g. 'idr', 'rid' and 'dir' would all mean insensitive + descending + reversed.
Example:
#!/usr/bin/perl
use strict;
use feature qw(switch say);
use List::Util qw(shuffle);
sub short_sorter {
my ($type) = @_;
# Legend:
# i = case insensitive
# a = ascending
# d = descending
# r = reverse (right to left)
# n = numbers
# l = length of value
my %sorter = (
'a' => sub { $a cmp $b },
'd' => sub { $b cmp $a },
);
given ($type) {
when ([qw[dr rd]]) { $sorter{$type} = sub { reverse($b) cmp re
+verse($a) }; }
when ([qw[ar ra]]) { $sorter{$type} = sub { reverse($a) cmp re
+verse($b) }; }
when ([qw[ai ia]]) { $sorter{$type} = sub { uc $a cmp uc $b };
+ }
when ([qw[di id]]) { $sorter{$type} = sub { uc $b cmp uc $a };
+ }
when ([qw[an na]]) { $sorter{$type} = sub { $a <=> $b }; }
when ([qw[nd dn]]) { $sorter{$type} = sub { $b <=> $a }; }
when ([qw[la al]]) { $sorter{$type} = sub { length($a) <=> len
+gth($b) }; }
when ([qw[ld dl]]) { $sorter{$type} = sub { length($b) <=> len
+gth($a) }; }
when ([qw[air ari iar ira rai ria]]) {
$sorter{$type} = sub { uc reverse($a) cmp uc reverse($b) }
+;
}
when ([qw[dir dri idr ird rdi rid]]) {
$sorter{$type} = sub { uc reverse($b) cmp uc reverse($a) }
+;
}
}
if ($type) {
return $sorter{$type} or die 'AAARGH!!';
}
else {
return (shuffle values %sorter)[0];
}
}
my @unsorted = qw(red lilac yelloW green cyan blue magenta);
my $criteria = short_sorter('dir');
my @sorted = sort $criteria @unsorted;
print "$_\n" for @sorted;
__DATA__
yelloW
green
cyan
blue
red
lilac
magenta
Update
The random option doesn't do the right thing in this version
Update 2
Corrected with respect to random option:
#!/usr/bin/perl
use strict;
use feature qw(switch say);
use List::Util qw(shuffle);
sub short_sorter {
my ($type) = @_;
# Legend:
# i = case insensitive
# a = ascending
# d = descending
# r = reverse (right to left)
# n = numbers
# l = length of value
my %sorter = (
a => sub { $a cmp $b },
d => sub { $b cmp $a },
ai => sub { uc $a cmp uc $b },
di => sub { uc $b cmp uc $a },
an => sub { $a <=> $b },
dn => sub { $b <=> $a },
al => sub { length($a) <=> length($b) },
dl => sub { length($b) <=> length($a) },
ar => sub { reverse($a) cmp reverse($b) },
dr => sub { reverse($b) cmp reverse($a) },
air => sub { uc reverse($a) cmp uc reverse($b) },
dir => sub { uc reverse($b) cmp uc reverse($a) },
);
given ($type) {
when ('dr') { $sorter{$type} = $sorter{dr} }
when ('ra') { $sorter{$type} = $sorter{ar} }
when ('ia') { $sorter{$type} = $sorter{ai} }
when ('id') { $sorter{$type} = $sorter{di} }
when ('na') { $sorter{$type} = $sorter{an} }
when ('nd') { $sorter{$type} = $sorter{dn} }
when ('la') { $sorter{$type} = $sorter{al} }
when ('ld') { $sorter{$type} = $sorter{dl} }
when ([qw[ari iar ira rai ria]]) {
$sorter{$type} = $sorter{air};
}
when ([qw[dri idr ird rdi rid]]) {
$sorter{$type} = $sorter{dir};
}
}
if ($type) {
return $sorter{$type} or die "Unknown options: $type";
}
else {
return (shuffle values %sorter)[0];
}
}
my @unsorted = qw(red lilac yelloW green cyan blue magenta);
my $criteria = short_sorter('dri');
my @sorted = sort $criteria @unsorted;
print "$_\n" for @sorted;
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