Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!decwrl!labrea!rutgers!mit-eddie!uw-beaver!ssc-vax!bcsaic!lbaum
From: lbaum@bcsaic.UUCP (Larry Baum)
Newsgroups: comp.lang.lisp
Subject: Re: Amusing Code
Message-ID: <7209@bcsaic.UUCP>
Date: 24 Aug 88 16:01:29 GMT
References: <389@soi.UUCP>
Reply-To: lbaum@bcsaic.UUCP (Larry Baum)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 22

In article <389@soi.UUCP> alex@soi.UUCP (Alex Zatsman) writes:
>
>(defvar *Stack*)
>
>(defun Push-Object (Object) (push Object (car *Stack*)))
>
>(defun Init-Stack () (setf *Stack* '((:Bottom-Frame))))
>
>(defun Test-Stack ()
>  (Init-Stack)     (print *Stack*)
>  (Push-Object 11) (print *Stack*)
>  (Init-Stack)     (print *Stack*)  (values))
>
This is another in a long series of examples that show the danger in
using quoted lists instead of the LIST function, and also using
"destructive" operations such as PUSH.

Of course the "correct" code should do:

(defun Init-Stack () (setf *Stack* (list '(:Bottom-Frame))))

LSB