[racket-dev] [racket] Question about fields in Racket OO

set!?

Try it in both positions (the commented out one and the other one):
the thing to keep in mind is that the declaration in c% is also kind
of like a set! that happens when the object is initialized.

Robby

#lang racket
(define c%
  (class object%
    (field [f 1])
    (define/public (get-f) f)
    (super-new)))

(define d%
  (class c%
    (inherit-field f)
    (set! f 2)
    (super-new)
    ; (set! f 2)
    ))

(send (new d%) get-f)

On Wed, Dec 15, 2010 at 11:46 PM, Mark Engelberg
<mark.engelberg at gmail.com> wrote:
> Thanks.  That seems to address the shared private issue.
>
> So is there a way to give a new value to an inherited field?
>
> --Mark
>
> On Wed, Dec 15, 2010 at 9:13 PM, Robby Findler <robby at eecs.northwestern.edu>
> wrote:
>>
>> See define-local-member-name.
>>
>> Robby
>>
>> On Wed, Dec 15, 2010 at 10:38 PM, Mark Engelberg
>> <mark.engelberg at gmail.com> wrote:
>> > I'm playing around with the object-oriented subset of Racket, and have a
>> > couple of questions.
>> >
>> > Ideally, I'd like to equip a class with a field that is visible only to
>> > it
>> > and its subclasses.  As far as I can tell, though, this isn't possible.
>> > It
>> > seems that I have to make a choice between a completely private field
>> > visible only to the class (by just using "define") or making a
>> > completely
>> > public field (by using "field").  Correct?
>> >
>> > Now, let's say I make the field public.
>> >
>> > In the subclass, how do I change the default value of field?
>> >
>> > For example, in the superclass, I might have
>> > (field [a 300])
>> >
>> > but in the subclass, I want to do something like
>> > (inherit-field [a 200])
>> >
>> > However, as far as I can tell, the syntax doesn't support anything other
>> > than
>> > (inherit-field a)
>> >
>> > Thanks,
>> >
>> > Mark
>> >
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>
>