Grafik i Racket

Grafikmotorer VI
(define *all-things* '())
(define (make-thing ...)
(define (update) ...)
(define (render canvas dc) ...)
(lambda (cmd)
(cond ((eq? cmd 'update) update)
((eq? cmd 'render) render))))
(define (render-fn canvas dc)
(define (render-one thing)
((thing 'render) canvas dc))
(for-each render-one *all-things*))
(define (tick!)
(define (update-one! thing)
((thing 'update))) ;;Kanske vill skicka med saker här
(for-each update-one! *all-things*)
(send *my-canvas* refresh))