From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Davis Herring" Newsgroups: gmane.emacs.devel Subject: Re: Why isn't the string returned by symbol-name read-only? Date: Sat, 23 Jan 2010 17:12:17 -0800 (PST) Message-ID: <15016.128.165.0.81.1264295537.squirrel@webmail.lanl.gov> References: <4B5B6250.1080108@censorshipresearch.org> Reply-To: herring@lanl.gov NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1264295562 8771 80.91.229.12 (24 Jan 2010 01:12:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 24 Jan 2010 01:12:42 +0000 (UTC) Cc: Emacs development discussions To: "Daniel Colascione" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Jan 24 02:12:35 2010 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1NYr1m-0000aV-4h for ged-emacs-devel@m.gmane.org; Sun, 24 Jan 2010 02:12:34 +0100 Original-Received: from localhost ([127.0.0.1]:46004 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NYr1m-0001VR-Fy for ged-emacs-devel@m.gmane.org; Sat, 23 Jan 2010 20:12:34 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NYr1g-0001U8-3S for emacs-devel@gnu.org; Sat, 23 Jan 2010 20:12:28 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NYr1a-0001PH-Ed for emacs-devel@gnu.org; Sat, 23 Jan 2010 20:12:26 -0500 Original-Received: from [199.232.76.173] (port=52297 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NYr1a-0001PB-85 for emacs-devel@gnu.org; Sat, 23 Jan 2010 20:12:22 -0500 Original-Received: from proofpoint2.lanl.gov ([204.121.3.26]:36439) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NYr1Z-0008Db-QP for emacs-devel@gnu.org; Sat, 23 Jan 2010 20:12:22 -0500 Original-Received: from mailrelay2.lanl.gov (mailrelay2.lanl.gov [128.165.4.103]) by proofpoint2.lanl.gov (8.14.3/8.14.3) with ESMTP id o0O1CH4D021949; Sat, 23 Jan 2010 18:12:17 -0700 Original-Received: from localhost (localhost.localdomain [127.0.0.1]) by mailrelay2.lanl.gov (Postfix) with ESMTP id BEBC415DE02D; Sat, 23 Jan 2010 18:12:17 -0700 (MST) X-NIE-2-Virus-Scanner: amavisd-new at mailrelay2.lanl.gov Original-Received: from webmail1.lanl.gov (webmail1.lanl.gov [128.165.4.106]) by mailrelay2.lanl.gov (Postfix) with ESMTP id AC37B15DDFC8; Sat, 23 Jan 2010 18:12:17 -0700 (MST) Original-Received: by webmail1.lanl.gov (Postfix, from userid 48) id A6A551DE01B7; Sat, 23 Jan 2010 18:12:17 -0700 (MST) Original-Received: from 128.165.0.81 (SquirrelMail authenticated user 196434) by webmail.lanl.gov with HTTP; Sat, 23 Jan 2010 17:12:17 -0800 (PST) In-Reply-To: <4B5B6250.1080108@censorshipresearch.org> User-Agent: SquirrelMail/1.4.8-5.7.lanl7 X-Priority: 3 (Normal) Importance: Normal X-Proofpoint-Virus-Version: vendor=fsecure engine=1.12.8161:2.4.5, 1.2.40, 4.0.166 definitions=2010-01-23_03:2010-01-20, 2010-01-23, 2010-01-23 signatures=0 X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6, seldom 2.4 (older, 4) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:120317 Archived-At: > That returns in an error when you try to evaluate it. The object > returned by (symbol-name 'car) must have some read-only bit set. > > Why isn't that bit set for *all* symbol names? It's set for that string not because `car' is too important to be changed, but because it was created before Emacs was dumped. (Of course, it is created that early because it is important.) Making such strings read-only saves the time in checking whether they might need garbage-collection later. So it's purely an optimization; it's not meant to protect anything. Davis -- This product is sold by volume, not by mass. If it appears too dense or too sparse, it is because mass-energy conversion has occurred during shipping.