I think you have to define your specific certain-class-equal?
So does record-type.
 2014年11月10日 下午8:58于 "Jan Nieuwenhuizen" <janneke@gnu.org>写道：

> Hi,
>
> In the example below, my implementation of equal? is only being
> used if both types are the same.  That surprised me; the manual
> says equal? becomes a generic and for normal generics this works
> as I expect.
>
> How do I get the magic equal? to do what show the same result as the
> simple generic type-equal?
>
> And also, do we want such surprises?
>
> Greetings,
> Jan
>
> (read-set! keywords 'prefix)
> (use-modules (oop goops))
>
> (define-class <type> ()
>   (name :accessor .name :init-value #f :init-keyword :name))
>
> (define-method (equal? (a <type>) (b <type>))
>   (display "<type>equal?\n")
>   (eq? (.name a) (.name b)))
>
> (define-method (equal? (a <type>) (b <symbol>))
>   (display "<type0>equal?\n")
>   (eq? (.name a) b))
>
> (define-method (type-equal? (a <type>) (b <symbol>))
>   (display "<type1>equal?\n")
>   (eq? (.name a) b))
>
> (format #t "equal?: ~a\n" (equal? (make <type> :name 'a) (make <type>
> :name 'a)))
> (newline)
> (format #t "equal?: ~a\n" (equal? (make <type> :name 'a) 'a))
> (newline)
> (format #t "type-equal?: ~a\n" (type-equal? (make <type> :name 'a) 'a))
> (newline)
>
>
> --
> Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond http://lilypond.org
> Freelance IT http://JoyofSource.com | Avatar®  http://AvatarAcademy.nl
>
>