#!/usr/bin/perl

use Data::Dumper;
use Animal::Dog;

my $rex = Animal::Dog->new();
print Dumper($rex);

##</code><code>##

package Animal;

use strict;
use warnings;

sub new {
    my ($class) = @_;
    my $proto = {need_oxygen => 1};
    return bless($proto, $class);
} 

1;

##</code><code>##

package Animal::Dog;
use base "Animal";

use strict;
use warnings;

sub new {
    my ($class) = @_;
    my $self = $class->SUPER::new();
    $$self{domesticated} = 1;
    return $self;
} 

1;

##</code><code>##

$VAR1 = bless( {
                 'domesticated' => 1,
                 'need_oxygen' => 1
               }, 'Animal::Dog' );