[racket] Creating a useful snip

copy.

Robby

On Tue, Apr 5, 2011 at 1:34 PM, Jay McCarthy <jay.mccarthy at gmail.com> wrote:
> I'm trying to create a useful snip that displays a different sub-snip
> every second. I think I've overridden every method required to get a
> "useful" snip, but nothing gets display in DrRacket and the functions
> aren't called ever. Are there other methods that need to be
> overridden?
>
> The code is below...
>
> Jay
>
> #lang racket/base
> (require (for-syntax racket/base)
>         racket/class
>         racket/function
>         racket/runtime-path
>         racket/snip)
>
> (define reactive-snip%
>  (class* snip% ()
>    (init-field sub-snips)
>
>    (printf "Snips: ~a\n" sub-snips)
>
>    (define (the-snip)
>      (list-ref sub-snips
>                (modulo (current-seconds) (length sub-snips))))
>
>    (define-syntax-rule (delegate id)
>      (define/override (id . a)
>        (define some-snip (the-snip))
>        (printf "Delegating (~a ~a) to ~a\n"
>                'id a
>                some-snip)
>        (send/apply some-snip id a)))
>
>    (delegate get-extent)
>    (delegate draw)
>    (delegate get-text)
>    ; set-unmodified or modified
>
>    (super-new)))
>
> (define-runtime-path img1 '(lib "PLT-206-larval.png" "icons"))
> (define-runtime-path img2 '(lib "PLT-206-mars.jpg" "icons"))
>
> (define sub-snips
>      (map (curry make-object image-snip%)
>           (list img1 img2)))
>
> (define x
>  (make-object
>      reactive-snip%
>    sub-snips))
>
> sub-snips
>
> x
>
> --
> Jay McCarthy <jay at cs.byu.edu>
> Assistant Professor / Brigham Young University
> http://faculty.cs.byu.edu/~jay
>
> "The glory of God is Intelligence" - D&C 93
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