For the record, this worked:
#lang typed/racket
(require typed/racket/class)
(define aninteger%
(class object%
(super-new)
(init-field [x : Integer 0])
(: getxinternal Integer)
(define getxinternal x)
(: getx (-> Integer))
(define/public (getx) getxinternal)))
(print (send (new aninteger% [x 2]) getx))
On Sunday, February 16, 2020 at 12:18:53 AM UTC+1, Alain De Vos wrote:
>
>
> Following code makes an "integerclass" with an "add" method :
>
> #lang racket
> (define (integerclass x)
> (define (getx) x)
> (define (setx! x_new) (set! x x_new))
> (define (add y)(integerclass (+ x (y 'getx))))
> (lambda (message . args)
> (case message
> ((getx) (apply getx args))
> ((setx!) (apply setx! args))
> ((add) (apply add args))
> (else (error "POINT: Unknown message ->" message)))))
>
> (define (myprint x) (print x)(newline))
> (define p1 (integerclass 1))
> (myprint (p1 'getx))
> (define p2 (integerclass 2))
> (myprint (p2 'getx))
> (define p3 (p1 'add p2))
> (myprint (p3 'getx))
>
> Question 1 : can this code be inproved, are there "better patterns" one
> can you.
> Question 2 : can i modify this code to use typed/racket. I tried but
> failed on the "apply" method in the code.
>
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