OK, it works when the set! occurs after the super-new. I didn't think set! would work at all in a class definition (as opposed to within a method); I was thinking of the whole system of defining classes as more of a declarative DSL that only allowed certain constructs.
Now that you point it out though, I see there is an example in the guide that does set! on an inherited field. Thanks, Mark On Wed, Dec 15, 2010 at 9:53 PM, Robby Findler <ro...@eecs.northwestern.edu>wrote: > 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.engelb...@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 < > ro...@eecs.northwestern.edu> > > wrote: > >> > >> See define-local-member-name. > >> > >> Robby > >> > >> On Wed, Dec 15, 2010 at 10:38 PM, Mark Engelberg > >> <mark.engelb...@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 > >> > > >> > _________________________________________________ > >> > For list-related administrative tasks: > >> > http://lists.racket-lang.org/listinfo/users > >> > > > > > >
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