my %breeds = ( cocker => 'dog::cocker', setter => 'dog::setter', ); sub new { my $class = shift; my $breed = shift; my $self = { }; if($breed) { my $breed_class = $breeds{$breed}; eval " use $breed_class "; die $@ if $@; $self = $breed_class->new(); } else { bless $self, $class; } return $self; }