scheme / racket super-type和访问struct属性

Question

我如何访问r的图层属性，1去哪里？我只能使用point-x和point-y访问2和3，即使它是一个共同值结构..

#lang racket

(define (object-constructor super-type layer)
  (struct commmon-value(layer)
    #:super super-type
    #:transparent
    #:property prop:procedure (lambda (self)
                                           layer))
  comm)

(struct point (x y) 
  #:transparent
  #:property prop:procedure (lambda (self)
                                      x y)))

(define r ((object-constructor struct:point 1) 2 3 4))
(point-x r)
(point-y r)
r
> (comm 2 3 4)

Answer 1

#lang racket

(struct layer (common) 
  #:transparent
  #:property prop:procedure (lambda (self) (layer-common self)))

(struct point layer (x y) 
  #:transparent
  #:property prop:procedure (lambda (self) (layer-common self)))

(define r (point 1 2 3))
(match-define (point c x y) r)

(r)
c
x 
y

输出结果为：

1
1
2
3