Classes are great, what about Roles?

• Roles can be thought of as partial or incomplete classes.
• Roles are composed, not inherited.
• Roles are horizontal re-use, rather than vertical.

package Equality;
use Moose::Role;

requires 'equal_to';

sub not_equal_to { 
    my ($self, $other) = @_;
    not $self->equal_to($other);
}