得到所有对象的字段

Question

在球拍中是否可以同时获取物体的所有区域？

我想基本上将对象转换为哈希表,其中字段名称为键,字段值为值.

我找到了一个函数(field-names obj),但后来我不知道如何使用返回的字段名来从obj中获取值.该函数get-field可用于获取字段的值,但我不知道如何使用它的值:

> (define x% (class object% (init-field x y) (super-new)))
> (define obj (make-object x% 1 2))
> (get-field x obj)
1
> (field-names obj)
'(y x)
> (define field-name (second (field-names obj)))
> field-name
'x
> (get-field field-name obj)
get-field: given object does not have the requested field
  field name: field-name
  object: (object:x% ...)
  errortrace...:
  context...:
    /usr/lib/racket/collects/racket/private/class-internal.rkt:4906:0: obj-error29
    /usr/lib/racket/collects/racket/private/misc.rkt:87:7

Answer 1

这里有一些代码可以帮助您入门

#lang racket

> (define x% (class object% (inspect #f) (init-field x y) (super-new)))
> (define obj (make-object x% 1 2))
> (let-values (((name field-cnt field-name-list field-accessor field-mutator super-class skipped) 
               (class-info x%)))
    (for/hash ((name field-name-list)
               (idx field-cnt))
      (values name (field-accessor obj idx))))
'#hash((x . -1) (y . 0))

您可能希望将检查器从#f更改为不易受攻击的程序,但可以根据需要打开.一般来说,阅读班级信息和检查员.