gistfile1.pl

# If you look at my Monger repository, imagine the following snippet being stuck in
# Monger.pm 

BEGIN {
    Moose::Meta::Class->meta->make_mutable;
    Moose::Meta::Class->meta->add_before_method_modifier('make_immutable', sub {
        my $self = shift;
        my $name = $self->name;

        # apply the dbref role if, and only if, we're a monger::document
        if($name->isa('Monger::Document') && $name ne 'Monger::Document') {
            ensure_all_roles($name, 'Monger::Role::::DBref');
        }
    });
    Moose::Meta::Class->meta->make_immutable;
};