Another concrete implementation
template object PolarPoint isa Point;
field x(p@PolarPoint) { … };
field y(p@PolarPoint) { … };
field rho(p@PolarPoint) := 0;
field theta(p@PolarPoint) := 0
method new_polar_point(rho0,theta0) {
concrete object isa PolarPoint {
Doesn’t reimplement the other methods (area, distance, etc.)