Solution Review: Implement Inheritance

package Shape {
    use Moose;
    
    sub area {
        die "area method must be overridden";
    }
}

package Rectangle {
    use Moose;
    extends 'Shape';

    has 'length' => (is => 'rw', isa => 'Num');
    has 'width'  => (is => 'rw', isa => 'Num');

    sub area {
        my $self = shift;
        return $self->length * $self->width;
    }
}

package Circle {
    use Moose;
    extends 'Shape';
    
    has 'radius' => (is => 'rw', isa => 'Num');
    
    sub area {
        my $self = shift;
        return 3.1416 * ($self->radius ** 2);
    }
}