I replied too early. If you run the following program,
;; v.6.11.0.4
(require 2htdp/universe)
(require 2htdp/image)
(define mt (empty-scene 200 100))
(define xx 100)
(define yy 50)
;; String -> String
(define (main initial)
(big-bang initial
(on-key (lambda (w ke)
;; String KeyEvent -> String or (stop-with String)
;; add ke to w if 1String, stop with RETURN
(cond
[(key=? ke "\r") (stop-with w)]
[(= (string-length ke) 1) (string-append w ke)]
[else w])))
(stop-when (lambda (w)
;; String -> Boolean
(= (string-length w) 10))
(lambda (w)
;; String -> Image
(place-image (text w 22 'red) xx yy mt)))
(on-draw (lambda (w)
;; String -> Image
(place-image (text w 22 'black) xx yy mt)))))
(main "")
(main "0123456789")
you will see that regardless how the final state comes about, the text is
colored red meaning it goes through the last-picture rendering function.
If I misunderstood your request, please explain more carefully.
Merry Christmas — Matthias
> On Dec 24, 2017, at 3:38 PM, Matthias Felleisen <matth...@ccs.neu.edu> wrote:
>
>
>> On Dec 18, 2017, at 11:05 AM, A Mauer-Oats <mauero...@gmail.com> wrote:
>>
>> I recently came across the following behavior in big-bang that was new to me.
>> I am writing in case I have misunderstood something.
>>
>> 1. (stop-with model) does not run the draw handler one last time
>> (this is documented but I'm not sure why this choice was made)
>
>
> I can’t find this in the documentation. It promises the same properties as
> stop-when (based on my reading).
>
>
>> This means that a conditional in the draw handler cannot be used to draw a
>> "win screen".
>>
>> 2. (stop-when predicate? final-draw-handler)
>> the final-draw-handler runs at the stop of the animation, even if predicate?
>> does not cause the animation to stop
>
>
> I don’t know what you mean by this last sentence. If predicate? is never
> true, the final-draw-handler won’t be called.
>
>
>> The final-draw-handler is a fine creation.
>> If we had access to it without the predicate? then students could use
>> stop-when and get their win screen drawn without any extra baggage.
>> For example:
>> (to-draw ...)
>> (to-draw-final ...)
>>
>> In addition, perhaps there could be an option / default of making the final
>> draw handler be the same as the ordinary draw handler.
>
> In my experience, the last picture shows something rather different than the
> regular one. (With apologies to McMurtry.)
>
> I will think about this and come up with a solution. — Matthias
>
>
>
>
>
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