From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Drew Adams" Newsgroups: gmane.emacs.bugs Subject: bug#12314: 24.2.50; `add-to-history': use `setq' with `delete' Date: Sat, 8 Sep 2012 09:54:27 -0700 Message-ID: References: <7602D24B74DE42CF9901322634B85CA2@us.oracle.com> <87sjas4mc2.fsf@gnu.org> <83ipbomv6e.fsf@gnu.org> <2C45207ADF0E46BC98AF1B486695F632@us.oracle.com> <83fw6smti6.fsf@gnu.org> <9A8F619FD7584123A6319BD089E444E4@us.oracle.com> <83bohgmrdv.fsf@gnu.org> <838vckmq4c.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Trace: ger.gmane.org 1347123348 7648 80.91.229.3 (8 Sep 2012 16:55:48 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 8 Sep 2012 16:55:48 +0000 (UTC) Cc: 12314@debbugs.gnu.org, cyd@gnu.org To: "'Eli Zaretskii'" , "'Andreas Schwab'" Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Sat Sep 08 18:55:49 2012 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1TAOJt-0007z8-Bf for geb-bug-gnu-emacs@m.gmane.org; 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Sat, 8 Sep 2012 16:54:37 GMT Original-Received: from abhmt109.oracle.com (abhmt109.oracle.com [141.146.116.61]) by acsmt358.oracle.com (8.12.11.20060308/8.12.11) with ESMTP id q88GsaRF029541; Sat, 8 Sep 2012 11:54:36 -0500 Original-Received: from dradamslap1 (/71.202.147.44) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 08 Sep 2012 09:54:35 -0700 X-Mailer: Microsoft Office Outlook 11 In-Reply-To: <838vckmq4c.fsf@gnu.org> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Thread-Index: Ac2N36DhYm4sn6RJR02cAiOKV2JZ5wAAWflQ X-Source-IP: ucsinet21.oracle.com [156.151.31.93] X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.13 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 140.186.70.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.bugs:63960 Archived-At: > > Even if the element is not the first one, you always have > > to think about other references that may exist to the > > cons that is removed. > > Sorry, I'm not sure how this is related. Please elaborate. (Think pointers.) A variable stays pointed to the same cons cell - these operations do not change that. But they can change the relations among cons cells: which of them point to which others. (setq a '(1 2 3 4)) (setq b (cddr a)) a => (1 2 3 4) b => (3 4) (delq 4 b) a => (1 2 3) b => (3) The value of variable `a' was changed by changing the value of `b', because `b' points to a cons cell that is used in the list structure pointed to by `a'.