jkh@pcsbst.UUCP (jkh) (08/19/89)
Ok, you're probably sick of me by this time, but I promise that the
question is a simple one. I've got AKCL/Victoria PCL (5/22/89) working,
but am confused by some of the behaviour I'm seeing:
Using the simple examples from the book "Object Oriented Programming in
Common Lisp" by Sonya E. Keene for "lock" classes:
(defclass lock ()
((name :initarg :name :reader lock-name))
(:documentation "The foundation of all locks."))
(defclass null-lock (lock)
()
(:documentation "A lock that is always free."))
(defclass simple-lock (lock)
((owner :initform nil :accessor lock-owner))
(:documentation "A lock that is either free or busy."))
I can create instances of both types of locks and query the names or set
the owner slot on the simple-lock type. However, getting to the next
set of examples, I get very different results.
Assuming that *null-lock* and *simple-lock* are instances of each, She says:
(type-of *null-lock*) => NULL-LOCK
(type-of *simple-lock*) => SIMPLE-LOCK
I get:
PCL>(type-of *null-lock*) => IWMC-CLASS
PCL>(type-of *simple-lock*) => IWMC-CLASS
Strange, no?
Also:
Doing (typep *simple-lock* 'simple-lock)
(typep *null-lock* 'null-lock)
and (type *simple-lock* 'lock)
Yield correct results.
However, she says that:
(subtypep 'simple-lock 'lock) => t t
(subtypep 'null-lock 'lock) => t t
(subtypep 'null-lock 'simple-lock) => t t
But I get:
PCL>(subtypep 'simple-lock 'lock) => NIL NIL
PCL>(subtypep 'null-lock 'simple-lock) => NIL NIL
PCL>(subtypep 'null-lock 'simple-lock) => NIL NIL
Any ideas?
Sigh. Trying to get this whole KCL/CLX/CLOS/CLUE stuff working together
is a *real* chore! I'm now beginning to understand why people are buying
DELPHI/IBUKI/LispWorks products. Still, it *is* interesting (haven't gotten
CLUE up yet, that should be fun). BTW, CLX is a *real dog*! Anybody know
why (besides the fact that the image is 6.9MB? :-)
Jordan
--
--------
Jordan Hubbard
PCS Computer Systeme GmbH
Munich, West Germany
UUCP: pyramid!pcsbst!jkh jkh@meepmeep.pcs.com
EUNET: unido!pcsbst!jkh
ARPA: jkh@violet.berkeley.edu hubbard@decwrl.dec.com