From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Lennart Borgman (gmail)" Newsgroups: gmane.emacs.help Subject: Re: Strange incf behavior in Emacs 22. Intentional? Date: Fri, 29 Jun 2007 01:29:52 +0200 Message-ID: <46844470.3010005@gmail.com> References: <1183034491.352998.214980@n2g2000hse.googlegroups.com> <85k5tn4sn7.fsf@lola.goethe.zz> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Trace: sea.gmane.org 1183073420 21088 80.91.229.12 (28 Jun 2007 23:30:20 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Thu, 28 Jun 2007 23:30:20 +0000 (UTC) Cc: help-gnu-emacs@gnu.org To: David Kastrup Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Jun 29 01:30:18 2007 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1I43RH-0004nj-OO for geh-help-gnu-emacs@m.gmane.org; Fri, 29 Jun 2007 01:30:15 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1I43RG-0002Oc-Us for geh-help-gnu-emacs@m.gmane.org; Thu, 28 Jun 2007 19:30:14 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1I43R2-0002Nj-IY for help-gnu-emacs@gnu.org; Thu, 28 Jun 2007 19:30:00 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1I43R1-0002Mr-3X for help-gnu-emacs@gnu.org; Thu, 28 Jun 2007 19:30:00 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1I43R0-0002Mo-Ur for help-gnu-emacs@gnu.org; Thu, 28 Jun 2007 19:29:58 -0400 Original-Received: from ch-smtp02.sth.basefarm.net ([80.76.149.213]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1I43Qz-0000iM-8o; Thu, 28 Jun 2007 19:29:57 -0400 Original-Received: from c83-254-133-189.bredband.comhem.se ([83.254.133.189]:60067 helo=[127.0.0.1]) by ch-smtp02.sth.basefarm.net with esmtp (Exim 4.66) (envelope-from ) id 1I43Qw-0005XZ-9W; Fri, 29 Jun 2007 01:29:55 +0200 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070604 Thunderbird/2.0.0.4 Mnenhy/0.7.5.666 In-Reply-To: <85k5tn4sn7.fsf@lola.goethe.zz> X-Antivirus: avast! (VPS 000752-3, 2007-06-28), Outbound message X-Antivirus-Status: Clean X-Originating-IP: 83.254.133.189 X-Scan-Result: No virus found in message 1I43Qw-0005XZ-9W. X-Scan-Signature: ch-smtp02.sth.basefarm.net 1I43Qw-0005XZ-9W a611157f7771ad59a1c9c692b244328f X-detected-kernel: Linux 2.6? (barebone, rare!) X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:45338 Archived-At: David Kastrup wrote: > "Lennart Borgman (gmail)" writes: > >> spamfilteraccount@gmail.com wrote: >>> Here are two functions: >>> >>> (defun testfun1 () >>> (interactive) >>> (setq a '(0 0)) >>> (print a)) >>> >>> (defun testfun2 () >>> (interactive) >>> (incf (car a)) >>> (print a)) >>> >>> >>> I call the first one, a is (0 0). >>> I call the second one, a is (1 0). >>> I call the second one, a is (2 0). >>> I call the first one, a is (2 0). >>> >>> "a" won't get the value (0 0) again until I redefine testfun1. >>> >>> I suspect it is caused be some kind of internal optimization. Is it >>> intentional? It cost me a great deal of head scratching to find out >>> why my program doesn't work. >> >> Are you using Emacs 22? Could you then please file a bug report? > > There is no bug, and no optimization involved. This is expected and > correct behavior (anything else would be _wrong_). A quoted list is > not regenerated when a function is entered new. A quoted list is > evaluated to a cons cell at _compile_ time. The contents of this cons > cell can be changed with setcar (or, in this case, incf). Ah, yes. I forgot about this case, but Juanma explained this before here.