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: How to get plist properties list? Date: Fri, 08 Jan 2021 00:20:59 -0500 Message-ID: References: <7eec4142-3c37-4084-9ea1-73df5df2c821@default> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="26353"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:OOMQcwpUYiTwcxVfDggu2Z7fPtE= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 08 06:22:50 2021 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 1kxkEb-0006bJ-Rf for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 06:22:49 +0100 Original-Received: from localhost ([::1]:42982 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kxkEa-0003yA-UN for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 08 Jan 2021 00:22:48 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:60540) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxkCv-0002J1-Sx for help-gnu-emacs@gnu.org; Fri, 08 Jan 2021 00:21:05 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:56318) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kxkCu-0003pa-NA for help-gnu-emacs@gnu.org; Fri, 08 Jan 2021 00:21:05 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kxkCt-0004lm-EM for help-gnu-emacs@gnu.org; Fri, 08 Jan 2021 06:21:03 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.248, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 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" Xref: news.gmane.io gmane.emacs.help:127091 Archived-At: > (dotimes (i length (reverse properties)) > (if (divisible-by-2-or-0-p i) > (push (elt plist i) properties))))) This is another example of a dotimes+elt loop, i.e. a loop where you end up with an unwarranted O(nē) complexity (i.e. a performance bug). > (while (/= n (length plist)) > (push (elt plist n) properties) > (setq n (+ 2 n))) > properties)) Same problem here. > But maybe there is some more simpler way to get plist properties list? Probably not the simplest but this should work: (defun plist-keys (plist) (let (keys iskey) (dolist (x plist) (if (setq iskey (not iskey)) (push x keys))) (nreverse keys))) The simplest might be: (map-keys plist) -- Stefan