From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp0 ([2001:41d0:2:bcc0::]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) by ms0.migadu.com with LMTPS id qN88MVvkaWDzAwAAgWs5BA (envelope-from ) for ; Sun, 04 Apr 2021 18:07:55 +0200 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp0 with LMTPS id mFYdK1vkaWDOPwAA1q6Kng (envelope-from ) for ; Sun, 04 Apr 2021 16:07:55 +0000 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id DF51922114 for ; Sun, 4 Apr 2021 18:07:54 +0200 (CEST) Received: from localhost ([::1]:59554 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lT5I1-0003aV-PB for larch@yhetil.org; Sun, 04 Apr 2021 12:07:53 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33942) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lT5H1-0003a3-VC for emacs-orgmode@gnu.org; Sun, 04 Apr 2021 12:06:52 -0400 Received: from ciao.gmane.io ([116.202.254.214]:57654) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lT5Gz-0005Mz-OI for emacs-orgmode@gnu.org; Sun, 04 Apr 2021 12:06:51 -0400 Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1lT5Gx-0002Mq-Fw for emacs-orgmode@gnu.org; Sun, 04 Apr 2021 18:06:47 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: emacs-orgmode@gnu.org From: Maxim Nikulin Subject: Re: Idea for handling timezones Date: Sun, 4 Apr 2021 23:06:41 +0700 Message-ID: References: <20210403150042.GK27597@maokai> <701561.1617475882@apollo2.minshall.org> <87y2dz54sk.fsf@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 In-Reply-To: Content-Language: en-US Received-SPF: pass client-ip=116.202.254.214; envelope-from=geo-emacs-orgmode@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: 28 X-Spam_score: 2.8 X-Spam_bar: ++ X-Spam_report: (2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_ADSP_CUSTOM_MED=0.001, FORGED_GMAIL_RCVD=1, FORGED_MUA_MOZILLA=2.309, FREEMAIL_FORGED_FROMDOMAIN=0.25, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.25, NICE_REPLY_A=-0.001, NML_ADSP_CUSTOM_MED=0.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-orgmode@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "General discussions about Org-mode." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-orgmode-bounces+larch=yhetil.org@gnu.org Sender: "Emacs-orgmode" X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1617552475; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:list-id:list-help: list-unsubscribe:list-subscribe:list-post; bh=oZHipR1m4Ap7bwg0wApNARsPgrauEpoDAkw0GdK2Fo8=; b=shlRZX3g/UpXGDOCPnTt+2VVhqyL96hVgJ5+JIVbALAbc/n8I4bPaAHp9D/VBf8ZOjno4S M/OuReWcctRRvtZemEWfzJ20cT7POGcyzURAvE4gSi5HWy+i73ovoFXgP0rIwGH3IhSC18 zZj26dYYpUauEqMHGLVRjalf4H86hQi3ZLwoZXEEb2rU1+IxUxS63eB8GWFv75oxlu/bgp P+LIpvAElbqQbP5TqnxjHgHpKZ7EzbX5C+9f/AnGXoifWYqpuurrMwsEijJrE7QrTUyQpV vatNFNUV2aUFSz8lqbcZJ0GlFrKXnWFEbvEHpMl5lTSSfP9avb61K5VSFwi+3w== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1617552475; a=rsa-sha256; cv=none; b=kBKqSuUZHg/v9c5FXr9F1TxI8wlOnFXFLNCj96c7ylkJ/aaiMg1ewa+FQVS2PU+FYSMZjX b6vecmVERrOAnt38Zis/Cm9bgK+qfgZfePG35u0DKDeiBYl9piYA8VPimmg9NHkCepBHZ7 d+ybHDOSoGfXl4phwDzpXjnWBXi4gJwQcpsWZ8I/Ao52djb/z2hzczBUIiWg/R0AaDRseb Z0rTG/+NOK6IGVct4LyJevuxCB7jJvOC45vjG6UN9oBUHQbYgr/LaZ2kx2HVhp0xxNXk2Y RhiKt7g7i73iR+FSrAQor/xoIi+HW2LJSQ3e5tfLRZQ+WLKwHNQ7DPY2zLDqzw== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=none; spf=pass (aspmx1.migadu.com: domain of emacs-orgmode-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=emacs-orgmode-bounces@gnu.org X-Migadu-Spam-Score: -1.84 Authentication-Results: aspmx1.migadu.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=gmail.com (policy=none); spf=pass (aspmx1.migadu.com: domain of emacs-orgmode-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=emacs-orgmode-bounces@gnu.org X-Migadu-Queue-Id: DF51922114 X-Spam-Score: -1.84 X-Migadu-Scanner: scn0.migadu.com X-TUID: lesEb9uGawLg The notes below are quite general and unrelated to particular message. On 04/04/2021 07:51, Tom Gillespie wrote: > > followed by a space and then the repeat or delay for example > [+10000-01-01 10:11:00,992315771-04:00 Sat] or > [-480-08-20 05:00+01:00] > or more temporally local > [2021-03-03 17:43-07:00 Sat] Just an idea, I do not know if it is feasible and convenient. Have anyone considered a kind of src blocks to describe timestamps? Current inline syntax is suitable for simple cases, sometimes more details are required, some information could be redundant to allow consistency check: - Date-time in the original form as it appeared in external source (with a hint related to particular format e.g. rfc822 date. - Either it is local time or it is bound to some event as Solar eclipse. - List if time zones to have notion of local time of all participants of an online meeting. - Location for planned event since there is a chance that existing time zone will be split into smaller ones. A couple of bookmarks to get impression of complexity: - https://stackoverflow.com/tags/timezone/info timezone Tag Info - https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time Falsehoods programmers believe about time and follow-ups. Emacs API is hardly suitable for working with multiple time zones. Something could be borrowed from other projects, e.g. https://howardhinnant.github.io/date_algorithms.html Low-Level Date Algorithms (C++) A special attribute has been added in python to deal with local time ambiguity around time transitions https://docs.python.org/3/library/datetime.html#datetime.datetime.fold https://www.python.org/dev/peps/pep-0495/ PEP 495 -- Local Time Disambiguation I think, it is a challenge to provide a convenient way to generate agenda for a trip across several time zones. P.S. Raw UNIX timestamp as 1234567890 is convenient for some computations but hardly human friendly. UTC date-time 2009-02-13T23:31:30Z is better. With particular offset 2009-02-13T22:31:30-01:00 it is equally precise and even more convenient. Still neither of such forms are applicable if it is scheduled event with fixed local time and offset of particular timezone might be changed.