note hardburn Polymorphism is a much more general concept, and we skip over that generality by starting with the factory piece first. See my reply below for why this isn't a good example of polymorphisim anyway. Update: [blue_cowdawg]'s update fix the OP's polymorphisim issue. I would be interested to see if the factory could be made without using eval, as well...I think it can, especially if the dogs were loaded previously in a more-safe matter. It can using <code>require $path_to_breed;</code> instead of <code>eval "use $breed;";</code>. But it ammounts to almost the same thing, except that you have to specifiy the path to the breed file instead of the traditional 'module::name' format. As you say, it's also possible to load all the subclasses before anything is called, but that could get very inefficient fast. My favored solution would be to map a breed via a hash: <code> 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; } </code> <div class="pmsig"> <div class="pmsig-195718"> ---- <code>: () { :|:& };:</code> Note: All code is untested, unless otherwise stated </div></div> 339131 339182