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Re: GOOPS %modify-[instance|class]
From: |
Mikael Djurfeldt |
Subject: |
Re: GOOPS %modify-[instance|class] |
Date: |
Fri, 10 Jan 2003 11:12:02 +0100 |
User-agent: |
Gnus/5.090008 (Oort Gnus v0.08) Emacs/21.2 (i386-pc-linux-gnu) |
Clinton Ebadi <address@hidden> writes:
> I think %modify-instance and -class should be public.
Could you be more specific why? These seem pretty strange and magical
to me, and might change as the implementation evolves...
> I specialized change-class and change-object-class (to the same
> thing, just to be safe because the manual says either one may be
> called but not both).
The manual shouldn't mention change-object-class since that is a
private part of the implementation. BTW, change-class is a generic
function while change-object-class is a prociedure.
> I seem to have a problem: when I return the updated class, all my
> pointers to the old class are invalidated! And then it seems that
> GOOPS continues in an infinite loops updated the same objects over
> and over again.
Could you please explain what you want to do. You talk about
returning an updated class. But this only happens if one is using
change-class to change the metaclass of a class instance. The normal
job for change-class is to change the class of an instance.
Here's an example of specialization to change-class:
(define-class <class-change-notice-class> (<class>))
(define-method (change-class (o <object>) (c <class-change-notice-class>))
(next-method)
(format #t "class changed for instance ~A\n" o))
(define-class c () (x) #:metaclass <class-change-notice-class>)
(define o (make c))
;;; Now we redefine c:
(define-class c () (x) (y) #:metaclass <class-change-notice-class>)
;;; If we now refer to o, it will be lazily updated:
o
-->
class changed for instance #<c 807f890>
#<c 807f890>
This seems to work.
Could you please give me enough information to reproduce the infinite
loop you are talking about?
Best regards,
Mikael Djurfeldt