Re: custom type `color' is not enforced

["Lennart Borgman (gmail)" <lennart.borgman@gmail.com>]

Richard Stallman wrote:
>     >     `C-h M-o color RET TAB' correctly gives all options defined with :type
>     >     `color' (rigid equality test). However, since Emacs currently does not
>     >     distinguish type `color' from type `string' (= this bug),
>     >
>     > That statement surprises me.  The two types have different names, and
>     > don't behave the same, so in what sense does Emacs not distinguish
>     > them?
> 
>     Please reread what I said:
> 
> You said Emacs does not distinguish type `color' from type `string'.
> That's mistaken; it does distinguish them.  They behave differently.
> 
> I agree it would be good to make `color' check for a valid color.
> I hope someone will do that.


Something like this?


(defun color-digits-p (color)
   (save-match-data
     (string-match (rx bos
                       "#"
                       (or (repeat 3 3 hex-digit)
                           (repeat 6 6 hex-digit))
                       eos)
                   color
                   )))

(defun widget-color-validate (widget)
   (let ((val (widget-value widget)))
     (unless (or
              ;;(color-defined-p val)
              (member val x-colors)
              (and (stringp val)
                   (color-digits-p val)))
       (widget-put widget :error (format "Invalid color: %S"
                                         (widget-value widget)))
       widget)))

(define-widget 'color 'editable-field
   "Choose a color name (with sample)."
   :format "%{%t%}: %v (%{sample%})\n"
   :size 10
   :tag "Color"
   :validate 'widget-color-validate
   :value "black"
   :complete 'widget-color-complete
   :sample-face-get 'widget-color-sample-face-get
   :notify 'widget-color-notify
   :action 'widget-color-action)

(defcustom test-color "black"
   "color test"
   :type 'color)