From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: [External] : Passing buffers to function in elisp Date: Tue, 07 Mar 2023 17:45:49 -0500 Message-ID: References: <87mt56hg4e.fsf@iki.fi> <87bklihln8.fsf@iki.fi> <87pm9yf0ph.fsf@web.de> <87v8jmkfd0.fsf@iki.fi> <87jzzsjkrp.fsf@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="37025"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Cc: help-gnu-emacs@gnu.org To: Petteri Hintsanen Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Tue Mar 07 23:46:38 2023 Return-path: Envelope-to: geh-help-gnu-emacs@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 1pZg4s-0009U3-Gy for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 07 Mar 2023 23:46:38 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pZg4P-00052v-D1; Tue, 07 Mar 2023 17:46:09 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pZg4L-0004rL-Ee for help-gnu-emacs@gnu.org; Tue, 07 Mar 2023 17:46:05 -0500 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pZg4G-0006yu-Hq for help-gnu-emacs@gnu.org; Tue, 07 Mar 2023 17:46:04 -0500 Original-Received: from pmg2.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id 51EF6808E1; Tue, 7 Mar 2023 17:45:58 -0500 (EST) Original-Received: from mail01.iro.umontreal.ca (unknown [172.31.2.1]) by pmg2.iro.umontreal.ca (Proxmox) with ESMTP id F3E35807D5; Tue, 7 Mar 2023 17:45:56 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1678229157; bh=5L0JDYqtnebbnVNffMBWUeeNcOGHhfQ6COCm33qnnNU=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=kpJdOKeiBmvAQ/h0mJP5L2IhvIwyL87h0vyWqfpSxmxb7MTyirGbAGfXAklMIAZ2g 51+Lc8xf07BEubLtRkKh+Kf7CYpFtfjKXpHZvH0Gk3uh9LW+wuiaN1o1L6RZMf0skp 38wOzoQ8AMEhw+eqk4akQ5mfxYEvoA0cfsDpp1SJt6O3sUwo1oqXUsi7CnCIl7LrdO k/9DXhlcCeyDP1qb/80EC/r5uD44VRiYXT8EQbpDQdLUnzDUAiOMEt9Q8HXry9T53G KU0LcUiM/ySlHZIFsWQ17W1JaZikUA4dHAQn8gRwJ1ATk7aQrMCgfPc8AeJHGnyLzW L+TA2aEeGEQWA== Original-Received: from pastel (unknown [216.154.34.24]) by mail01.iro.umontreal.ca (Postfix) with ESMTPSA id BEDBF12252F; Tue, 7 Mar 2023 17:45:56 -0500 (EST) In-Reply-To: <87jzzsjkrp.fsf@iki.fi> (Petteri Hintsanen's message of "Tue, 07 Mar 2023 23:48:10 +0200") Received-SPF: pass client-ip=132.204.25.50; envelope-from=monnier@iro.umontreal.ca; helo=mailscanner.iro.umontreal.ca X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:142940 Archived-At: >> This is a typical a source of unnecessary O(N=B2) complexity: the above >> line takes O(N) time, so if you do it O(N) times, you got your >> N=B2 blowup. You're usually better off doing >> >> (push (plist-get page :stream) stream-chunks) >> >> and then at the end get the `stream` with >> >> (mapconcat #'identity (nreverse stream-chunks) nil) >> or >> (apply #'vconcat (nreverse stream-chunks)) > > Right, I see. Stream chunks are in this case byte vectors, so > just reversing those chunks does not do the trick. > But surely I can get from an order of N=B2 to 2N or so. I'm suggesting to build a list of chunks backward and to reverse *the list*, not the chunks. So the end result should still be the same. > Okay, this is something I did not foresee. But what about eval-defun > and eval-... in general? They are very convenient when trying out > things. It's OK to use them, of course. It usually means you still have 98% of your code compiled. >> The compiler is your friend. He can help you get the code in good >> shape :-) > I'm afraid that even the compiler cannot help against quadratic > complexity blunders. :-) It's just a friend, yes. Stefan