#! /bin/perl

use Data::Dumper;

my $hash = {
        'wheels' => {
                'four' => {
                        'car' => {
                                'plain' => {
                                        'sporty' => 'honda',
                                        'retro' => 'volkswagon',
                                        },
                                'fancy' => {
                                        'red' => 'ferrari',
                                        'silver' => 'maserati',
                                        },
                                },
                        'truck' => {
                                'light' => {
                                        'chevy' => 'pickup',
                                        },
                                'utility' => {
                                        'us' => 'mail',
                                        'city' => 'trash',
                                        'muni' => 'power',
                                        },
                                },
                        },
                'one' => 'Unicycle',
                'two' => {
                        'pedals' => 'bicycle',
                        'motorized' => 'motorcycle',
                        },
                'three' => 'tricycle',
                },
        };


##---------------------------
## DEEP REFERENCE
##---------------------------

fetch($hash, 'wheels');
fetch($hash, 'wheels', 'one');
fetch($hash, 'wheels', 'four', 'truck', 'utility');
fetch($hash, 'wheels', 'four', 'truck', 'utility', 'blah'); # doesn't exist

sub fetch {
        my ($hash, @keys) = @_;
        print "==> Fetching [" . join(', ', @keys) . ']' . "\n";
        my $results = deep_reference($hash, @keys);
        print Dumper($results), "\n\n";
        }

sub deep_reference {
        my ($hash, @keys) = @_;
        my $ref = undef;
        my $code = '$hash->' . join('->', map { "{$_}" } @keys);
        return eval $code;
        }