From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: empty-directory predicate, native implementation Date: Sun, 18 Oct 2020 05:47:45 +0300 Message-ID: <83ft6cs10u.fsf@gnu.org> References: <83y2ka18t7.fsf@gnu.org> <87y2kaj799.fsf@gmx.de> <83blh60wgr.fsf@gnu.org> <87h7qxjh7g.fsf@gmx.de> <878sc8kgy8.fsf@gmx.de> <87imbcls71.fsf@gmx.de> <83eem0zt0b.fsf@gnu.org> <87k0vsrd6m.fsf@gmx.de> <83a6wozs7h.fsf@gnu.org> <87sgafq2e2.fsf@gmx.de> <87h7qvptm3.fsf@gmx.de> <871rhxp8we.fsf@gmx.de> <237bd21b-96c7-4433-a5bc-34b64a9f4250@default> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="29927"; mail-complaints-to="usenet@ciao.gmane.io" Cc: michael.albinus@gmx.de, arthur.miller@live.com, emacs-devel@gnu.org To: Drew Adams Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sun Oct 18 04:48:15 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 1kTyk2-0007hj-AJ for ged-emacs-devel@m.gmane-mx.org; Sun, 18 Oct 2020 04:48:14 +0200 Original-Received: from localhost ([::1]:60886 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kTyk1-0002Wl-Cy for ged-emacs-devel@m.gmane-mx.org; Sat, 17 Oct 2020 22:48:13 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:46654) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kTyjY-00026Q-Iv for emacs-devel@gnu.org; Sat, 17 Oct 2020 22:47:44 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:36917) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kTyjX-0003wE-4N; Sat, 17 Oct 2020 22:47:43 -0400 Original-Received: from [176.228.60.248] (port=4663 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1kTyjW-00061A-Im; Sat, 17 Oct 2020 22:47:42 -0400 In-Reply-To: <237bd21b-96c7-4433-a5bc-34b64a9f4250@default> (message from Drew Adams on Sat, 17 Oct 2020 13:03:35 -0700 (PDT)) 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:257982 Archived-At: > Date: Sat, 17 Oct 2020 13:03:35 -0700 (PDT) > From: Drew Adams > Cc: Eli Zaretskii , emacs-devel@gnu.org > > I don't understand why we would do this. Is the > real aim to be able to have an empty-directory > predicate, i.e., to be able to see if there are > no files in a directory? It could be useful to know that a directory has at least N files in it, and the complexity of stopping a loop after N iterations is the same as stopping after 1 iteration. > If so, then why not do just that, witout > bothering (changing the signature of) > `directory-files'? The signature got an additional optional argument, which is backward compatible. And it is now trivial to implement the predicate for an empty directory based on the modified directory-files. > And what is the order that defines which file > is first, second, etc.? Without knowing that, > what use is getting the "first" N? As discussed: on some filesystems the order is known in advance. Not sure how important that is.