class precedence list

From: Anthony Beurive' <>
Date: Tue, 12 Oct 1999 16:12:21 +0200

I got a problem with class precedence. I will simplify the problem
for clarity. Consider the following class definitions:

(define-class <A> () ())
(define-class <B> (<A>) ())
(define-class <C> (<A>) ())
(define-class <D> (<B>) ())
(define-class <E> (<C>) ())
(define-class <F> (<D> <E>) ())

The class precedence list of <F> resulting of a call to
class-precedence-list gives the following: (<F> <D> <E> <B> <A> <C>).
I believe this brakes the first rule of class precedence given in the
reference manual p. 87: "Each class is more specific than its
superclasses." Obviously, <C> is more specific than <A>, but it
appears later.

Is it a well-known problem of class precedence in STklos or CLOS? I
must admit I'm new to this kind of problems.

I can see two solutions that don't really satisfy me. The first one
is <B> not to inherit from <A>. The second is to explicitly specify
the class precedence list of <F>: (define-class <F> (<D> <E> <B> <C>)
()) or (define-class <F> (<D> <E> <B> <C> <A>) ()). Do other
solutions exist? Maybe I should modify the class-precedence-list

LaBRI (Univ. Bordeaux I)
351, cours de la Liberation
33405 Talence, FRANCE
Received on Tue Oct 12 1999 - 16:12:30 CEST

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