RE: Re: CLOS+defstruct issues

I added two files to the patches directory:

http://www.cormanlisp.com/CormanLisp/patches/2_01/

which fix this problem with :include in DEFSTRUCT.

Honestly, I was never aware of this feature, so didn't implement it,
although it makes perfect sense.

Thanks for tracking down the problem.

Roger

-----Original Message-----
From: news [mailto:news@xxxxxxxxxxxxxx] On Behalf Of Frode Vatvedt Fjeld
Sent: Friday, March 14, 2003 10:43 AM
To: cormanlisp@xxxxxxxxxxxxxxx
Subject: [cormanlisp] Re: CLOS+defstruct issues


Kenny Tilton <ktilton@xxxxxxxxxx> writes:

> Here is the source of talk.lisp, into which I pasted ACL results of 
> each
> test after they were run:
>
> (in-package :cl-user)
>
> (defstruct aaa xxx)
> (defstruct (bbb (:include aaa)) yyy)
> (defstruct (ccc (:include bbb)) zzz)

The problem is in Corman's defstruct. The classes generated by defstruct
don't get appropriate class-precedence-lists. As you can see, the
classes aaa and bbb are missing:

  (class-precedence-list (find-class 'ccc))
  => (#<Standard-Class CCC #xF30C80> #<Standard-Class STRUCTURE
#x1405498>
      #<Standard-Class T #x146DDC8>)

This means that the method dispatch won't recognize ccc objects as
instances of aaa or bbb.

Strangely, this still works:

  (typep (make-ccc) 'bbb)
  => t

Fix defstruct, and your method dispatch will work too.

-- 
Frode Vatvedt Fjeld



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