From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Jeremiah Dodds Newsgroups: gmane.emacs.devel Subject: Re: Usefulness of (t nil) as the last sexp in (cond ...) constructs? Date: Sun, 19 Aug 2012 06:23:15 -0400 Message-ID: <87ipcf6uzw.fsf@friendface.i-did-not-set--mail-host-address--so-tickle-me> References: <87mx1rthxb.fsf@altern.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1345371820 1724 80.91.229.3 (19 Aug 2012 10:23:40 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 19 Aug 2012 10:23:40 +0000 (UTC) Cc: emacs-devel@gnu.org To: Bastien Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Aug 19 12:23:40 2012 Return-path: Envelope-to: ged-emacs-devel@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 1T32fO-0005sP-5A for ged-emacs-devel@m.gmane.org; Sun, 19 Aug 2012 12:23:34 +0200 Original-Received: from localhost ([::1]:51197 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T32fM-00080G-GS for ged-emacs-devel@m.gmane.org; Sun, 19 Aug 2012 06:23:32 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:37021) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T32fK-00080A-Cr for emacs-devel@gnu.org; Sun, 19 Aug 2012 06:23:31 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T32fI-0005pb-Go for emacs-devel@gnu.org; Sun, 19 Aug 2012 06:23:30 -0400 Original-Received: from mail-iy0-f169.google.com ([209.85.210.169]:53493) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T32fI-0005pX-CP for emacs-devel@gnu.org; Sun, 19 Aug 2012 06:23:28 -0400 Original-Received: by iahk25 with SMTP id k25so1941052iah.0 for ; Sun, 19 Aug 2012 03:23:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version:content-type:content-transfer-encoding; bh=EQRYW3YXPoTVWPd3I+DUjQir++xJOPl05V3GUe5OVXU=; b=kvj1g+B0s53dq6jH1V6G+Thb7zF9zmYRIqE+X3sjuMXFbcKe7gN/T33uXKm+huModk 1xthuldEN4DSbGXScJsRExCG0qStz0W8vMhVHug+WSi3GRRS4896BwGTPtcwfn1XLUhI Qm89w3eMwc5gVh1xM5gv2HznAseZtes2InQWcQNwR6oWr6iTaXbexrjgFMm7Y625Au/v 0OxFpbLU1m2QBrdduReFHMDeBNbKZ8AMPexGt5XO21DCLu4wCjXsm0ykdaZryAgXU2a5 VZ33UKaj7oad5FrX7gEWsvkcFMkNzDxXXHVjdqz8O1cnEhaE2VNPxVo4Ha/0y8OvtWig SGZQ== Original-Received: by 10.50.188.130 with SMTP id ga2mr6808600igc.32.1345371807193; Sun, 19 Aug 2012 03:23:27 -0700 (PDT) Original-Received: from friendface (cpe-184-56-72-181.neo.res.rr.com. [184.56.72.181]) by mx.google.com with ESMTPS id xm2sm19479721igb.3.2012.08.19.03.23.25 (version=SSLv3 cipher=OTHER); Sun, 19 Aug 2012 03:23:26 -0700 (PDT) In-Reply-To: <87mx1rthxb.fsf@altern.org> (Bastien's message of "Sun, 19 Aug 2012 09:07:09 +0200") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.2.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 209.85.210.169 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:152665 Archived-At: Bastien writes: > There are many places in *.el elisp files where we have this construct > > (cond (...) > (...) > (t nil)) > > My understanding is that (t nil) is useless, since the =CC=80t' condition= =20 > is only tested if other conditions are `nil'. > > What is the purpose of (t nil)? IIRC, it's mostly there to make it explicit that "this cond is expected to return nil sometimes". > Can we safely remove it? Again, IIRC, it shouldn't affect behaviour to do so, but it might not be preferable.=20 --=20 Jeremiah Dodds blog : http://jdodds.github.com github : https://github.com/jdodds freenode : exhortatory twitter : kaens