Example of the general class pattern (original) (raw)

(define (point x y) (let ((x x) (y y) )

(define (getx) x)

(define (gety) y)

(define (add p) (point (+ x (send 'getx p)) (+ y (send 'gety p))))

(define (type-of) 'point)

(define (self message) (cond ((eqv? message 'getx) getx) ((eqv? message 'gety) gety) ((eqv? message 'add) add) ((eqv? message 'type-of) type-of) (else (error "Undefined message" message))))

self))