There's not currently a way to attach structure-type properties to classes (as opposed to objects).
I don't seem any immediate technical problems with adding support for properties on classes, but there are design questions --- such as whether and how a class's properties apply to subclasses --- that we'd have to sort out if attaching properties to classes seems useful enough. At Thu, 5 Jun 2014 12:14:46 -0400, "Alexander D. Knauth" wrote: > I’m just wondering, would it be possible to make a class be a function that > would be equivalent to (make-object % arg …)? > > Is there a way to attach structure-type properties to classes, instead of to > instances of classes? > > Because if there is, then procedure-arity could work on the class. > > My first instinct was to do this: (I know why it doesn’t work) > #lang racket > > (define with-constructor% > (interface* () > ([prop:procedure (lambda (this . args) > (send/apply this constructor args))]) > constructor > )) > > (define point% > (class* object% (with-constructor%) > (super-new) (inspect #f) > (init-field [x 0] [y 0]) > (define/public (constructor . args) > (apply make-object this% args)) > )) > > (define p (point% 1 2)) > > But this doesn’t work because it attaches the structure type properties to > instances of the class instead of to the class itself. > > Is there a way to attach structure-type properties to classes, instead of to > instances of classes? > > On Jun 5, 2014, at 11:32 AM, Roman Klochkov <kalimeh...@mail.ru> wrote: > > > For any procedure I can use procedure-arity. But how to get the number of > init arguments for a class? > > > > Or maybe there are any other way to make a contract, like in Guide 7.3.9, > where one can compare number of arguments and arity of the function, but when > using (make-object someclass ...) > > instead of the function. > > > > > > -- > > Roman Klochkov > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
