From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.help Subject: Re: About setf extensions Date: Fri, 15 Feb 2013 15:11:21 +0100 Message-ID: <871uchmzue.fsf@web.de> References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1360937395 7056 80.91.229.3 (15 Feb 2013 14:09:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 15 Feb 2013 14:09:55 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Feb 15 15:10:15 2013 Return-path: Envelope-to: geh-help-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 1U6LzP-0004nf-Rs for geh-help-gnu-emacs@m.gmane.org; Fri, 15 Feb 2013 15:10:11 +0100 Original-Received: from localhost ([::1]:47251 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U6Lz5-0002vQ-MD for geh-help-gnu-emacs@m.gmane.org; Fri, 15 Feb 2013 09:09:51 -0500 Original-Received: from eggs.gnu.org ([208.118.235.92]:52895) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U6Lyw-0002uz-T8 for help-gnu-emacs@gnu.org; Fri, 15 Feb 2013 09:09:46 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1U6Lyv-0006xh-5s for help-gnu-emacs@gnu.org; Fri, 15 Feb 2013 09:09:42 -0500 Original-Received: from mout.web.de ([212.227.15.3]:54339) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1U6Lyu-0006xM-T4 for help-gnu-emacs@gnu.org; Fri, 15 Feb 2013 09:09:41 -0500 Original-Received: from drachen.dragon ([92.74.177.220]) by smtp.web.de (mrweb001) with ESMTPSA (Nemesis) id 0Lr2I7-1Ub22K222V-00ebX6; Fri, 15 Feb 2013 15:09:39 +0100 Mail-Followup-To: help-gnu-emacs@gnu.org In-Reply-To: (Xue Fuqiao's message of "Fri, 15 Feb 2013 21:07:36 +0800") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) X-Provags-ID: V02:K0:gQ3PPUFnKpsagtc3g1lDsvyY00QqHneH5KBM5Us8C5F PUdJUy8viIjsgIv+jB6gu10b+0SZv+SuRiPBO1gBxlAFweCP9O wasGqHD3bpA5QsHngPR+Sq4j3GXWz0H1TgUmV/qOTi3hbL+rWQ U+vBsFECrCLPHc8xRdlTYGEV6rrOjeNBhNhPGGSWd977pcRDz+ TnAetOgwCBM4hX3AXOogv+SXlVZza8ewPnpV3pg6Tc= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] X-Received-From: 212.227.15.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:89107 Archived-At: Xue Fuqiao writes: > In (info "(cl) Setf Extensions"): > > Most of these have directly corresponding "set" functions, like > `use-local-map' for `current-local-map', or `goto-char' for > `point'. A few, like `point-min', expand to longer sequences of > code when they are used with `setf' (`(narrow-to-region x > (point-max))' in this case). > > I don't understand the `point-min' example. What does the "x" mean > here? I know it is the START argument of `narrow-to-region', but where > is it from? And where will it be used? Thanks. I guess it's the value the generalized variable `(point-min)' should be set to. I.e., (setf (point-min) x) is translated to (narrow-to-region x (point-max)) This seems reasonable, because afterwards, (point-min) will give x. Regards, Michael.