Hi,
I'm getting an error when I try to use 'apply' on an inherited method:
colourwell.rkt:60:47: class: misuse of method (not in application) in: set
I feel I've missed something in my reading of the reference manual for apply
or inheriting methods, but I don't know where I've gone wrong?
I'm sure this is a simple thing, but I'd love it if someone could tell me
where I've gone wrong.
Seasons greetings,
Stephen
---
Details follow:
I have a little class colour% to which I'm adding a simple HSV mapping
I wanted to
(define/public (set-hsv hue saturation value)
(apply set (hsv->rgb hue saturation value)))
But I had to
(define/public (set-hsv hue saturation value)
(define set-rgb (lambda (r g b) (set r g b)))
(apply set-rgb (hsv->rgb hue saturation value)))
I have set the class definition to inherit 'set':
(define colour% (class color%
(inherit red green blue set)
-class-definition--
(define colour% (class color%
(inherit red green blue set)
(define (hsv->rgb h s v)
(if (= s 0)
(list v v v)
(let* ((var_h (* h 6))
(var_i (floor var_h));
(var_1 (* v (- 1 s)));
(var_2 (* v (- 1 (* s (- var_h var_i)))));
(var_3 (* v (- 1 (* s (- 1 (- var_h
var_i)))))))
(case (floor var_h)
((0) {list v var_3 var_1})
((1) {list var_2 v var_1})
((2) {list var_1 v var_3})
((3) {list var_1 var_2 v})
((4) {list var_3 var_1 v})
(else {list v var_1 var_2})))))
(define (rgb->hsv r g b); -> (list h s v)
(define minVal (min r g b))
(define maxVal (max r g b))
(define delta (- maxVal minVal))
(define v maxVal)
(append
(if (= delta 0)
(list 0 0)
;; else
(list (/ delta maxVal) ; s
(let* (
(del_R (/ (+ (/ (- maxVal r) 6) (/
delta 2)) delta))
(del_G (/ (+ (/ (- maxVal g) 6) (/
delta 2)) delta))
(del_B (/ (+ (/ (- maxVal b) 6) (/
delta 2)) delta))
(h (cond
((= r maxVal) (- del_B del_G))
((= g maxVal) (+ (/ 1 3) del_R (-
del_B)))
((= b maxVal) (+ (/ 2 3) del_G (-
del_R))))))
(cond
((< h 0) (+ h 1))
((> h 1) (- h 1))))))
(list v)))
(super-new)
(define/public (hue)
(car (rgb->hsv (red) (green) (blue))))
(define/public (saturation)
(second (rgb->hsv (red) (green) (blue))))
(define/public (value)
(third (rgb->hsv (red) (green) (blue))))
(define/public (set-hsv hue saturation value)
(define set-rgb (lambda (r g b) (set r g b)))
(apply set-rgb (hsv->rgb hue saturation value)))
))
_________________________________________________
For list-related administrative tasks:
http://lists.racket-lang.org/listinfo/users
