From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: Re: looking-at-p slower than looking-at Date: Wed, 25 Nov 2015 21:39:04 +0100 Message-ID: <87egfdzudz.fsf@mbork.pl> References: <87r3js7e8l.fsf@linux-qg7d.fritz.box> <87y4dzv1b3.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1448483995 19253 80.91.229.3 (25 Nov 2015 20:39:55 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 25 Nov 2015 20:39:55 +0000 (UTC) Cc: help-gnu-emacs@gnu.org To: Barry Margolin Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Nov 25 21:39:44 2015 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 1a1gqs-0006XD-Ic for geh-help-gnu-emacs@m.gmane.org; Wed, 25 Nov 2015 21:39:42 +0100 Original-Received: from localhost ([::1]:47606 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a1gqu-0003pp-EJ for geh-help-gnu-emacs@m.gmane.org; Wed, 25 Nov 2015 15:39:44 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53125) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a1gqj-0003pZ-1Y for help-gnu-emacs@gnu.org; Wed, 25 Nov 2015 15:39:33 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a1gqf-0004SS-1T for help-gnu-emacs@gnu.org; Wed, 25 Nov 2015 15:39:32 -0500 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:54509) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a1gqe-0004SM-RI for help-gnu-emacs@gnu.org; Wed, 25 Nov 2015 15:39:28 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id 4E8898F2003; Wed, 25 Nov 2015 21:39:07 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id SLzjiBABCokG; Wed, 25 Nov 2015 21:39:05 +0100 (CET) Original-Received: from localhost (unknown [109.232.24.28]) by mail.mojserwer.eu (Postfix) with ESMTPSA id B3B3B8F2002; Wed, 25 Nov 2015 21:39:04 +0100 (CET) User-agent: mu4e 0.9.13; emacs 25.0.50.1 In-reply-to: X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6.x X-Received-From: 195.110.48.8 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:108222 Archived-At: On 2015-11-25, at 16:48, Barry Margolin wrote: > In article , > Nicolas Richard wrote: > >> Marcin Borkowski writes: >> >> > You might also (depending on your use-case) want to use looking-at-p, >> > which is marginally slower than looking-at, but does not modify match >> > data. >> >> Why is it slower and how much slower is it ? I don't see how it can >> happen from its implementation: >> >> (defsubst looking-at-p (regexp) >> "\ >> Same as `looking-at' except this function does not change the match data." >> (let ((inhibit-changing-match-data t)) >> (looking-at regexp))) >> >> thanks, > > It takes a tiny amount of time to bind the variable > inhibit-changing-match-data. That's why it's a little slower. > > On the other hand, it doesn't have to set the internal variables that > hold the match data, so maybe they cancel out. Ah, I didn't think of that. Stupid me. (That might be the answer to the question why my benchmarks were inconclusive.) Thanks, -- Marcin Borkowski http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski Faculty of Mathematics and Computer Science Adam Mickiewicz University