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

Thanks Matt,

I'll have go at this right after my nap.

Guenther

P.S. I didn't know that lambda had been introduced yet.

Matthias Felleisen wrote:
>  For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> 
> You will need a callback for each button. When the event happens the 
> callback
> to this button is triggered. Do it manually for each button and then 
> follow the
> design recipe from this section to abstract over the button creation 
> process in
> general
> 
>  (map (lambda (row) (map make-button row)) pad)
> 
> and the button callback function in particular. -- Matthias
> 
> P.S. I promise it will be enlightening.
> 
> On Saturday, November 29, 2003, at 10:30 AM, 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
>>
> 
>