From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Is add-to-list supposed to work when lexical-binding is t? Date: Tue, 04 Jun 2013 22:41:59 -0400 Message-ID: References: <1370306529.4188.YahooMailClassic@web141101.mail.bf1.yahoo.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1370400329 32095 80.91.229.3 (5 Jun 2013 02:45:29 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 5 Jun 2013 02:45:29 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Jun 05 04:45:27 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 1Uk3j4-0007yT-HW for geh-help-gnu-emacs@m.gmane.org; Wed, 05 Jun 2013 04:45:26 +0200 Original-Received: from localhost ([::1]:40704 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uk3j4-00031M-77 for geh-help-gnu-emacs@m.gmane.org; Tue, 04 Jun 2013 22:45:26 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:39357) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uk3in-0002uT-IP for help-gnu-emacs@gnu.org; Tue, 04 Jun 2013 22:45:14 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Uk3ii-0006JY-Dl for help-gnu-emacs@gnu.org; Tue, 04 Jun 2013 22:45:09 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:51608) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Uk3ii-0006Fx-7z for help-gnu-emacs@gnu.org; Tue, 04 Jun 2013 22:45:04 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Uk3ig-0007fO-W6 for help-gnu-emacs@gnu.org; Wed, 05 Jun 2013 04:45:03 +0200 Original-Received: from 69-165-139-76.dsl.teksavvy.com ([69.165.139.76]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 05 Jun 2013 04:45:02 +0200 Original-Received: from monnier by 69-165-139-76.dsl.teksavvy.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 05 Jun 2013 04:45:02 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 22 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 69-165-139-76.dsl.teksavvy.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) Cancel-Lock: sha1:uk8NK0HkUOIs0Y79wNkMHbyQNqQ= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 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:91310 Archived-At: >> > (let ((x '(a))) (add-to-list 'x 'b) x) -> (b a) >> Yup, this is asking for trouble. Use `push' or `cl-pushnew' instead. > Unless you're knee-deep in the internals of the language, the difference > between `cl-pushnew' and `add-to-list' is so obscure as to be > incomprehensible. Agreed. I never liked add-to-list, and now I really know why. To give you an idea of why `add-to-list' is a problem: (add-to-list 'o 'b) does the same as (add-to-list (intern (substring "ouch" 0 1)) 'b) so other than by ad-hoc handling the case where the first arg is passed via quoting, the byte-compiler would have to handle both cases, and the second case is pretty hopeless. Stefan