Unsorted List:beta, apple, gamma globulin, alpha, zeta, gesorenplatz!!, gamma, delta, foolish mortal,
Sorted List:, beta, zeta, alpha, apple, delta, gamma, foolish mortal, gamma globulin, gesorenplatz!!

##</code><code>##

#!/usr/bin/perl -w
#
# Orcish_Ex.pl
#
# Exercises from the "Orcish Sorting" section of perlmonks tutorial node
# "Resorting to Sorting" (id=node 128722).
#
# Exercise 1:
#       Q: Why should you make the caching hash viewable only by the
#       sorting function?  How is this accomplished?
#
#       A: To avoid namespace pollution.  By declaring locally in a block.
#       (My answers.  I haven't checked 'em yet.)
#       NOTE: while coding it up, I started to suspect that %cache should
#       be nulled out, or successive sort calls could botch it up.  Is it
#       a problem?  See Orcish_Ex_test.pl
#
# Exercise 2:
#       Use Orcish Manuever to sort a list of strings in the same way as
#       described in Naive section, Exercise 1.
#
# Note: Yes, there is an intentional blank line at the end so we can see
#       where the empty string will sort to!
#
use strict;
use warnings;

# Orcish section
{
        my %cache;
        sub len_or_str {
                my $va = ($cache{$a} ||= [ length($a), substr($a,0,5) ]);
                my $vb = ($cache{$b} ||= [ length($b), substr($b,0,5) ]);
                return  ($va->[0] <=> $vb->[0])
                        or ($va->[1] cmp $vb->[1]);
        }

        sub print_cache {
                print "Cache after sort:\n";
                for my $k (keys %cache) {
                        print "\t", $k, " => [", $cache{$k}->[0], ", ",
                                $cache{$k}->[1], "]\n";
                }
        }
}

sub print_msg_list {
        my $msg = shift @_;
        print $msg, join(", ", @_), "\n";
}

my @unsorted = <DATA>;
chomp @unsorted;

&print_msg_list("Unsorted List:", @unsorted);

my @sorted = sort len_or_str @unsorted;

&print_msg_list("Sorted List:", @sorted);

&print_cache;

__DATA__
beta
apple
gamma globulin
alpha
zeta
gesorenplatz!!
gamma
delta
foolish mortal