From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.ciao.gmane.io!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: emacs rendering comparisson between emacs23 and emacs26.3 Date: Sat, 04 Apr 2020 18:53:45 -0400 Message-ID: References: <83h7y63sjj.fsf@gnu.org> <834ku43c61.fsf@gnu.org> <83k12zz6ds.fsf@gnu.org> <054393f3-3873-ab6e-b325-0eca354d8838@gmx.at> <20200403174757.GA8266@ACM> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="ciao.gmane.io:159.69.161.202"; logging-data="25105"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) Cc: Alan Mackenzie , eliz@gnu.org, rrandresf@gmail.com, rms@gnu.org, emacs-devel@gnu.org To: martin rudalics Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Apr 05 00:54:42 2020 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jKrgX-0006S7-N2 for ged-emacs-devel@m.gmane-mx.org; Sun, 05 Apr 2020 00:54:41 +0200 Original-Received: from localhost ([::1]:42804 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jKrgW-0004NA-Ph for ged-emacs-devel@m.gmane-mx.org; Sat, 04 Apr 2020 18:54:40 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:40824) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jKrfp-0003sA-Nx for emacs-devel@gnu.org; Sat, 04 Apr 2020 18:54:01 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jKrfn-00045c-T7 for emacs-devel@gnu.org; Sat, 04 Apr 2020 18:53:56 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:13459) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jKrfm-00041x-CL; Sat, 04 Apr 2020 18:53:54 -0400 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 32BBA80D58; Sat, 4 Apr 2020 18:53:53 -0400 (EDT) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 691F180D7C; Sat, 4 Apr 2020 18:53:47 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1586040827; bh=ZTepw0+boNuoj4Q9Mz5AOTU4kileoYx9IWajVZthiko=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=i95v+3rsIf8lVaHi2ZUtJ0qHQdO9z46m9IZhlZPCsZuFGZJVYSsHGyuJIGuEtfbq4 BIQjlCZRJfUfZEit2xREX59TzW6TEqge4zfA0n/Gvym57bCyCiWwAwOZt6tyL+imxv o8hsrOV6m61X4JPKWLXum0waVgiVhCs3dMdQaRqILWJuW0mTi8Jo98TfVoNkS8oeGe RqfzEsrGN6qIT0S8vixzGEQSsip4bvbJEnLcZ+NBOQ9yMT1btR79ACGKDHFzkyP7HQ wHF1px05DdxLOXuw9N9qRvB39LhC9vuEkJjN1gf094Vl0bjZneVCT7RBMr+Nc6tnGH /UzNXzDwDrp2g== Original-Received: from alfajor (unknown [104.247.241.114]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id EB8FE12064D; Sat, 4 Apr 2020 18:53:46 -0400 (EDT) In-Reply-To: (martin rudalics's message of "Sat, 4 Apr 2020 10:56:27 +0200") X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 132.204.25.50 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.23 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:246429 Archived-At: > I still don't understand why it had to be eliminated. Defaulting it to > nil but respecting a non-nil value would have been completely sufficient > IMHO. I can answer why it wasn't changed to nil: 1- o-p-i-c-0-i-d-s had an "invisible" effect on `forward-comment`, where the only visible effect was that sometimes it caused `forward-comment` to misbehave. This use was just an optimization. Setting the var to nil avoided the misbehavior but could result in *much* worse performance in some cases (e.g. calling `parse-partial-sexp` from `point-min` once per line skipped when scanning text backward, so O(N*M) where N is the size of the buffer and M is the distance we're moving). So just changing the var to nil was really not an option, it needed to be replaced by *another* optimization. BTW, I still see not reason to link this other optimization, which relies on `syntax-ppss` with the scrolling performance problems you are seeing, especially if it's only visible in CC-mode buffers and not in things like Javascript (which have an almost identical syntax-table). 2- o-p-i-c-0-i-d-s also had (and still has) an effect on `beginning-of-defun` and this effect is supposed to be visible and predictable. It's not just an optimization. So changing the var to nil would have changed the behavior of `beginning-of-defun` and there was a very clear resistance to that. Another reason not to just change its value to nil. I also can't imagine how defaulting to nil "would have been completely sufficient IMHO": setting the var to nil had been an option for decades but it never enjoyed much popularity. Stefan