[plt-scheme] Re: HTDP Exercise 22.3.3. - Hint needed

Hi Matt,

I'm not a 100% whether or not this is what you (plural) had in mind, 
well it does work.

I've used the functions returning functions in this case, however it 
seems a bit odd, I mean yes it works, but doesn't this produce more 
overhead compared to using a generalized function with parameters instead?

Guenther

;;model

(define pad
   '((1 2 3)
     (4 5 6)
     (7 8 9)
     (\# 0 *)))

(define pad2
   '((1 2 3  +)
     (4 5 6  -)
     (7 8 9  *)
     (0 = \. /)))

;; view

(define md (make-message "n"))

(define (pad->gui title a-list)
   (cons
    (list (make-message title))
    (cons (list md)
          (traverse a-list))))

(define (traverse a-list)
   (cond
     ((empty? a-list) empty)
     ((list? a-list)
      (cons (traverse (first a-list))
            (traverse (rest a-list))))
     (else
      (make-button
       (cond
         ((symbol? a-list) (symbol->string a-list))
         (else (number->string a-list)))
       (fun-composer a-list)))))


;; controller

(define (fun-composer a-string)
   (local
       ((define (cb e)
          (draw-message md (cond
                             ((symbol? a-string)(symbol->string a-string))
                             (else (number->string a-string))))))
     cb))

(create-window (pad->gui "PHONE" pad))


Guenther Schmidt wrote:
>  For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> 
> Hi,
> 
> I've developed the code following code but I have one problem: How do I 
> identify the button that was pressed?
> 
> When I specify the callback function to a button do I need to pass 
> specific arguments, in short: I don't know how it's done.
> 
> ;; model
> 
> (define pad
>   '((1 2 3)
>     (4 5 6)
>     (7 8 9)
>     (\# 0 *)))
> 
> (define pad2
>   '((1 2 3  +)
>     (4 5 6  -)
>     (7 8 9  *)
>     (0 = \. /)))
> 
> 
> ;; view
> 
> (define md (make-message "n"))
> 
> (define (pad->gui title a-list)
>   (cons
>    (list (make-message title))
>    (cons (list md)
>          (traverse a-list))))
> 
> (define (traverse a-list)
>   (cond
>     ((empty? a-list) empty)
>     ((list? a-list)
>      (cons (traverse (first a-list))
>            (traverse (rest a-list))))
>     (else
>      (make-button
>       (cond
>         ((symbol? a-list) (symbol->string a-list))
>         (else (number->string a-list)))
>       test))))
> 
> ;; controller
> 
> (define (test e)
>   (draw-message md "2"))
> 
> (create-window (pad->gui "PHONE" pad))
> 
> 
> 
> Cheers
> 
> Guenther
> 
> 
>