From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Time resolution in Emacs Date: Mon, 25 Apr 2022 09:38:00 -0700 Organization: UCLA Computer Science Department Message-ID: References: <5ed963b2-3fa8-48d8-627e-bc0571d15b43@gmail.com> <4a23f3a4-fe8f-d396-49d8-10034803be63@gmail.com> <52fb10fb-892a-f273-3be8-28793f27e204@cs.ucla.edu> <5cd820d4-ae67-43d4-9e63-c284d51ff1e4@gmail.com> <83tuapvcxs.fsf@gnu.org> <6efc5d24-34a2-fd30-cd20-fe4ac3e48310@cs.ucla.edu> <83fsm8tdzl.fsf@gnu.org> <9e4781b2-2ffa-b1ce-09b4-ead82cad9038@cs.ucla.edu> <83ilr3siku.fsf@gnu.org> <4e41671c-fae8-61c4-845c-4c7ba4317e88@cs.ucla.edu> <83fsm7sh2s.fsf@gnu.org> <83czhbsgc2.fsf@gnu.org> <33fb24fb-282b-cc13-a597-e7b63f19982d@cs.ucla.edu> <83y1zzq6kd.fsf@gnu.org> <837d7hr8s3.fsf@gnu.org> <83h76kq5c6.fsf@gnu.org> <9afbcc3d-b57c-b5bf-e4f6-52b352f99af8@cs.ucla.edu> <83bkwspa1r.fsf@gnu.org> <3008dea1-572b-9010-f3c4-15272145fd8a@cs.ucla.edu> <83mtg9m9en.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="5921"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Cc: manikulin@gmail.com, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Apr 25 18:38:43 2022 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 1nj1jW-0001OY-VP for ged-emacs-devel@m.gmane-mx.org; Mon, 25 Apr 2022 18:38:42 +0200 Original-Received: from localhost ([::1]:56694 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nj1jV-0002cW-Fq for ged-emacs-devel@m.gmane-mx.org; Mon, 25 Apr 2022 12:38:41 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:44956) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nj1iw-0001xW-M8 for emacs-devel@gnu.org; Mon, 25 Apr 2022 12:38:06 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:37142) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nj1iu-0001va-SI; Mon, 25 Apr 2022 12:38:06 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id AE62B1600DB; Mon, 25 Apr 2022 09:38:01 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id VX5J3yoZ2p83; Mon, 25 Apr 2022 09:38:01 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 002241600E5; Mon, 25 Apr 2022 09:38:00 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id d-ErY8NrNX8U; Mon, 25 Apr 2022 09:38:00 -0700 (PDT) Original-Received: from [192.168.1.9] (cpe-172-91-119-151.socal.res.rr.com [172.91.119.151]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id CA9061600DB; Mon, 25 Apr 2022 09:38:00 -0700 (PDT) Content-Language: en-US In-Reply-To: <83mtg9m9en.fsf@gnu.org> Received-SPF: pass client-ip=131.179.128.68; envelope-from=eggert@cs.ucla.edu; helo=zimbra.cs.ucla.edu X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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:288863 Archived-At: On 4/25/22 09:10, Eli Zaretskii wrote: > What do you do if you get a timestamp whose > fractional part looks like .123000 -- do you consider this to be > millisecond resolution or microsecond resolution? The latter. That's standard practice, pretty much everywhere. > we'd > get in trouble as result of trivial arithmetics on timestamps Whatever trouble we get into, will be less trouble than we get with arbitrarily converting to a resolution that differs from that of the incoming timestamp. More generally, we can't do a perfect job with timestamp resolution, but that's OK. There's never perfection in timestamps anyway. What we can do, is do a better job than what we're currently doing. > It's very hard to keep only that many significant digits when working > with fractional numbers. It's not hard to send a textual timestamp. Emacs does this sort of thing routinely when printing floats, and fractions are easier than floats. And Emacs code that computes timestamps internally can continue to use whatever resolution it is currently using; it doesn't need to arbitrary limit that resolution.