From: Luc Teirlinck <teirllm@dms.auburn.edu>
Cc: emacs-devel@gnu.org
Subject: Re: Is this a bug of Emacs-Lisp?
Date: Fri, 17 Feb 2006 11:57:42 -0600 (CST) [thread overview]
Message-ID: <200602171757.k1HHvgc14231@raven.dms.auburn.edu> (raw)
In-Reply-To: <87slqipmde.fsf@emacsfans.org> (message from Zhang Wei on Fri, 17 Feb 2006 13:47:41 +0800)
Zhang Wei wrote:
(defun dummy () '(1 . 2))
(dummy)
=> (1 . 2)
(setcdr (dummy) 3)
(dummy)
=> (1 . 3)
Modify the return value of dummy changed it's defination. Is this
a bug of Elisp?
No. You get the same result in Common Lisp if you replace, in the
above, setcdr with rplacd.
If it's not. How does this happen?
If a function returns a quoted cons, then after you change the cdr of
the cons, it still returns that (now changed) cons.
Using (defun dummy (cons 1 2)) will prevent this.
Sincerely,
Luc.
next prev parent reply other threads:[~2006-02-17 17:57 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-17 5:47 Is this a bug of Emacs-Lisp? Zhang Wei
2006-02-17 16:21 ` Giorgos Keramidas
2006-02-18 5:26 ` Drew Adams
2006-02-18 6:42 ` Drew Adams
2006-02-18 16:18 ` Andreas Schwab
2006-02-17 16:28 ` Andreas Schwab
2006-02-17 17:20 ` David Kastrup
2006-02-17 17:57 ` Luc Teirlinck [this message]
2006-02-17 18:18 ` Luc Teirlinck
2006-02-17 19:24 ` Alan Mackenzie
2006-02-17 19:29 ` Kevin Rodgers
2006-02-17 22:34 ` Sascha Wilde
2006-02-18 18:34 ` Richard M. Stallman
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