David Pirotte <da...@altosw.be> writes: > Hi Mark, > >> > When using GOOPS, if a class has a second slot, the #:getter procedure >> > of the first slot returns the value of the second slot when applied to >> > an instance of a subclass. >> > >> > (use-modules (oop goops)) >> > >> > (define-class <foo> () >> > (a #:init-form 'foo #:getter foo-a) >> > (b #:init-form 42)) >> > >> > (define-class <bar> (<foo>) >> > (a #:init-form 'bar)) >> > >> > (foo-a (make <foo>)) => foo >> > (foo-a (make <bar>)) => 42 >> > >> > I expected: >> > >> > (foo-a (make <bar>)) => bar > >> Indeed, CLOS behaves as you expected... > > Are you sure about that?
Read this: http://clhs.lisp.se/Body/07_ec.htm In particular: "In general, more than one class among C and its superclasses can define a slot with a given name. In such cases, only one slot with the given name is accessible in an instance of C, and the characteristics of that slot are a combination of the several slot specifiers, computed as follows: [...]" Here's a transcript of an SBCL session I tried on Debian: --8<---------------cut here---------------start------------->8--- This is SBCL 1.0.57.0.debian, an implementation of ANSI Common Lisp. More information about SBCL is available at <http://www.sbcl.org/>. SBCL is free software, provided as is, with absolutely no warranty. It is mostly in the public domain; some portions are provided under BSD-style licenses. See the CREDITS and COPYING files in the distribution for more information. * (defclass foo () ((a :initform 'foo :reader foo-a) (b :initform 42))) #<STANDARD-CLASS FOO> * (defclass bar (foo) ((a :initform 'bar))) #<STANDARD-CLASS BAR> * (values (foo-a (make-instance 'foo)) (foo-a (make-instance 'bar))) FOO BAR --8<---------------cut here---------------end--------------->8--- Unknown_lamer on #guile tried the same thing with a different implementation of Common Lisp, and got the same answer. Mark
