package Top::Base;
use Moose; 1;

package SubordinateA; use Moose; extends 'Top::Base'; 1;

package SubordinateB; use Moose; extends 'Top::Base'; 1;


##</code><code>##

package Top;

sub new {
    my ($class, %options) = @_;
    my $impl= "Top::$options{ base }";
    $impl->new( %options );
};