[racket] Creating a useful snip

It would've help me find the problem, but I already knew to look at
the doc page for what to override, so if that is updated, I don't
think I could be blamed.

Jay

2011/4/5 Robby Findler <robby at eecs.northwestern.edu>:
> Does it make sense to have snip%'s copy method signal an error instead
> of returning a (useless) snip%? or maybe it could check and see if
> this is a subclass and signal an error in that case?
>
> Robby
>
> On Tuesday, April 5, 2011, Matthias Felleisen <matthias at ccs.neu.edu> wrote:
>>
>> Please!
>>
>> On Apr 5, 2011, at 3:06 PM, Jay McCarthy wrote:
>>
>>> Should I update the docs to mention that as one that must be overridden?
>>>
>>> Jay
>>>
>>> 2011/4/5 Robby Findler <robby at eecs.northwestern.edu>:
>>>> 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
>>>>> _________________________________________________
>>>>>  For list-related administrative tasks:
>>>>>  http://lists.racket-lang.org/listinfo/users
>>>>>
>>>>
>>>
>>>
>>>
>>> --
>>> 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
>>>
>>> _________________________________________________
>>>  For list-related administrative tasks:
>>>  http://lists.racket-lang.org/listinfo/users
>>
>>
>



-- 
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