Scheme/Lisp 定义一个类

;;定义一个类必须在类名字后面加%，这个是Scheme语法规定 object%是超类
(define email% (class object%
                         (init to from)
                         (define To to)
                         (define From from)
                         (super-new)
                         (define/public (send) (display From))
                         (define/public (receviver) (displayer To))
                         (define/public (change-sender new-sende-name)
                                                (set! From new-sende-name))))

(define email-one (new email% (to 'hh) (from 'ss)));;定义第一个email
(define email-two (make-object email% 'fg 'bb));; 定义第二个,make-object 创建一个对象！
(send email-one sender) ;;发送第一个
(send email-two sender);;发送第二个
(send email-one change-sender 'xxxxx);;重新定义第一个