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.bugs Subject: bug#54764: encode-time: make DST and TIMEZONE fields of the list argument optional ones Date: Wed, 20 Apr 2022 12:17:47 -0700 Organization: UCLA Computer Science Department Message-ID: <37ffb641-a4da-89fd-6ef5-909db5a5fe3c__5124.57673191733$1650484239$gmane$org@cs.ucla.edu> References: <5ed963b2-3fa8-48d8-627e-bc0571d15b43@gmail.com> <149de00f-115b-5367-414f-c7700ef8966b@cs.ucla.edu> <2d57e59b-f971-483b-ad65-e0c5ff7883e8@gmail.com> <3624beb8-71fd-924e-a065-74d0034ed351@cs.ucla.edu> <8ba9e258-dd24-a0a0-1aa6-9c2831c05af0@gmail.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------s60V0Pd46BU99QesSH0ZmI3j" Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="24659"; 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: orgmode , 54764@debbugs.gnu.org To: Max Nikulin Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Wed Apr 20 21:50:31 2022 Return-path: Envelope-to: geb-bug-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 1nhGLP-0006Cl-0P for geb-bug-gnu-emacs@m.gmane-mx.org; 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Wed, 20 Apr 2022 12:17:48 -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 23io3Q-7kAZr; Wed, 20 Apr 2022 12:17:48 -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 E47951600CC; Wed, 20 Apr 2022 12:17:47 -0700 (PDT) Content-Language: en-US In-Reply-To: <8ba9e258-dd24-a0a0-1aa6-9c2831c05af0@gmail.com> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:230330 Archived-At: This is a multi-part message in MIME format. --------------s60V0Pd46BU99QesSH0ZmI3j Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable On 4/20/22 09:56, Max Nikulin wrote: > A typo: double "a". Thanks, fixed in the attached which I installed in master. > If I get your idea correctly then "January, 31" + "1 month" should be=20 > more impressive as impossible date. Thanks, good idea; also in the attached patch. > I can not figure out which elisp function can help to=20 > determine wall time for Aug 1 start of day in Cairo: >=20 > Africa/Cairo=C2=A0 Thu Jul 31 21:59:59 2014 UT =3D Thu Jul 31 23:59:59 = 2014 EET=20 > isdst=3D0 gmtoff=3D7200 > Africa/Cairo=C2=A0 Thu Jul 31 22:00:00 2014 UT =3D Fri Aug=C2=A0 1 01:0= 0:00 2014=20 > EEST isdst=3D1 gmtoff=3D10800 >=20 > input: 2014-08-01 Africa/Cairo > (timezone may be implicit as the system one) > expected output: 01:00:00 Given mktime's limitations there's no trivial way to do this for=20 arbitrary timestamps, since 00:00 doesn't exist in Cairo that day.=20 Worse, in some locations near the International Date Line entire days do=20 not exist, because at 00:00 they advanced the clocks forward 24 hours in=20 order to move the date line. It sounds like you're asking for a function that, given a date, yields=20 the first broken-down timestamp on or after 00:00 of that date. For=20 something like that, I'd use encode-time on 00:00 of that date to get a=20 timestamp T, and then use time-add and decode-time to decode T-86400=20 seconds, T, and T+86400 seconds, and if the decoded times all look fine=20 then return (decode-time T). If not (i.e., their UTC offsets differ, or=20 T's decoded time is not 00:00 on the correct date) I'd use binary search=20 to find discontinuities between T-86400 and T+86400 and look next to=20 those discontinuities to find timestamps closer to what you want. Of course this is not ideal - but it's similar to what many mktime=20 implementations do internally, and it's also similar to what Emacs's=20 cal-dst already does (maybe you can look there for ideas), so you'd be=20 in good company. --------------s60V0Pd46BU99QesSH0ZmI3j Content-Type: text/x-patch; charset=UTF-8; name="0001-More-encode-time-pitfall-doc-fixes.patch" Content-Disposition: attachment; filename="0001-More-encode-time-pitfall-doc-fixes.patch" Content-Transfer-Encoding: base64 RnJvbSBmOThjM2Y0NDI2ZmVjZjc5NGY0N2YyN2FlYmUxZjNiODU0ZmIxYmZkIE1vbiBTZXAg MTcgMDA6MDA6MDAgMjAwMQpGcm9tOiBQYXVsIEVnZ2VydCA8ZWdnZXJ0QGNzLnVjbGEuZWR1 PgpEYXRlOiBXZWQsIDIwIEFwciAyMDIyIDEyOjAzOjE5IC0wNzAwClN1YmplY3Q6IFtQQVRD SF0gTW9yZSBlbmNvZGUtdGltZSBwaXRmYWxsIGRvYyBmaXhlcwoKKiBkb2MvbGlzcHJlZi9v cy50ZXhpIChUaW1lIENvbnZlcnNpb24pOiBJbXByb3ZlIGRpc2N1c3Npb24gb2YKZW5jb2Rl LXRpbWUgcGl0ZmFsbHMgYmFzZWQgb24gY29tbWVudHMgYnkgTWF4IE5pa3VsaW4gKEJ1ZyM1 NDc2NCM2MykuCi0tLQogZG9jL2xpc3ByZWYvb3MudGV4aSB8IDIyICsrKysrKysrKysrKysr LS0tLS0tLS0KIDEgZmlsZSBjaGFuZ2VkLCAxNCBpbnNlcnRpb25zKCspLCA4IGRlbGV0aW9u cygtKQoKZGlmZiAtLWdpdCBhL2RvYy9saXNwcmVmL29zLnRleGkgYi9kb2MvbGlzcHJlZi9v cy50ZXhpCmluZGV4IGNhYmFlMDg5NzAuLjQxMzhkYWIwOWYgMTAwNjQ0Ci0tLSBhL2RvYy9s aXNwcmVmL29zLnRleGkKKysrIGIvZG9jL2xpc3ByZWYvb3MudGV4aQpAQCAtMTY3MCw3ICsx NjcwLDcgQEAgVGltZSBDb252ZXJzaW9uCiBjb252ZW50aW9uLCBAdmFye2RzdH0gaXMgQG1p bnVze30xIGFuZCBAdmFye3pvbmV9IGRlZmF1bHRzIHRvIHRoZQogY3VycmVudCB0aW1lIHpv bmUgcnVsZSAoQHB4cmVme1RpbWUgWm9uZSBSdWxlc30pLgogV2hlbiBtb2Rlcm5pemluZyBh biBvYnNvbGVzY2VudCBjYWxsZXIsIGVuc3VyZSB0aGF0IHRoZSBtb3JlLW1vZGVybgotbGlz dCBlcXVpdmFsZW50IGNvbnRhaW5zIDkgZWxlbWVudHMgd2l0aCBhIGEgQGNvZGV7ZHN0fSBl bGVtZW50IHRoYXQKK2xpc3QgZXF1aXZhbGVudCBjb250YWlucyA5IGVsZW1lbnRzIHdpdGgg YSBAY29kZXtkc3R9IGVsZW1lbnQgdGhhdAogaXMgQG1pbnVze30xLCBub3QgQGNvZGV7bmls fS4KIAogWWVhciBudW1iZXJzIGxlc3MgdGhhbiAxMDAgYXJlIG5vdCB0cmVhdGVkIHNwZWNp YWxseS4gIElmIHlvdSB3YW50IHRoZW0KQEAgLTE2OTUsMjIgKzE2OTUsMjggQEAgVGltZSBD b252ZXJzaW9uCiBGb3IgZXhhbXBsZToKIAogQGxpc3AKLTs7IFRyeSB0byBjb21wdXRlIHRo ZSB0aW1lIGZvdXIgeWVhcnMgZnJvbSBub3cuCis7OyBUcnkgdG8gY29tcHV0ZSB0aGUgdGlt ZSBvbmUgbW9udGggZnJvbSBub3cuCiA7OyBXYXRjaCBvdXQ7IHRoaXMgbWlnaHQgbm90IHdv cmsgYXMgZXhwZWN0ZWQuCiAobGV0ICgodGltZSAoZGVjb2RlLXRpbWUpKSkKLSAgKHNldGYg KGRlY29kZWQtdGltZS15ZWFyIHRpbWUpCi0gICAgICAgICgrIChkZWNvZGVkLXRpbWUteWVh ciB0aW1lKSA0KSkKKyAgKHNldGYgKGRlY29kZWQtdGltZS1tb250aCB0aW1lKQorICAgICAg ICAoKyAoZGVjb2RlZC10aW1lLW1vbnRoIHRpbWUpIDEpKQogICB0aW1lKQogQGVuZCBsaXNw CiAKIEBub2luZGVudAogVW5mb3J0dW5hdGVseSwgdGhpcyBjb2RlIG1pZ2h0IG5vdCB3b3Jr IGFzIGV4cGVjdGVkIGlmIHRoZSByZXN1bHRpbmcKLXRpbWUgaXMgaW52YWxpZCBkdWUgdG8g ZGF5bGlnaHQgc2F2aW5nIHRyYW5zaXRpb25zLCB0aW1lIHpvbmUgY2hhbmdlcywKK3RpbWUg aXMgaW52YWxpZCBkdWUgdG8gbW9udGggbGVuZ3RoIGRpZmZlcmVuY2VzLAorZGF5bGlnaHQg c2F2aW5nIHRyYW5zaXRpb25zLCB0aW1lIHpvbmUgY2hhbmdlcywKIG9yIG1pc3NpbmcgbGVh cCBkYXlzIG9yIGxlYXAgc2Vjb25kcy4gIEZvciBleGFtcGxlLCBpZiBleGVjdXRlZCBvbgot RmVicnVhcnkgMjksIDIwOTYgdGhpcyBjb2RlIHlpZWxkcyBhIG5vbmV4aXN0ZW50IGRhdGUg YmVjYXVzZSAyMTAwIGlzCi1ub3QgYSBsZWFwIHllYXIuICBUbyBhdm9pZCBzb21lICh0aG91 Z2ggbm90IGFsbCkgb2YgdGhlIHByb2JsZW0sIHlvdQorSmFudWFyeSAzMCB0aGlzIGNvZGUg eWllbGRzIGEgbm9uZXhpc3RlbnQgZGF0ZSBGZWJydWFyeSAzMCwKK3doaWNoIEBjb2Rle2Vu Y29kZS10aW1lfSB3b3VsZCBhZGp1c3QgdG8gZWFybHkgTWFyY2guCitTaW1pbGFybHksIGFk ZGluZyBmb3VyIHllYXJzIHRvIEZlYnJ1YXJ5IDI5LCAyMDk2IHdvdWxkIHlpZWxkIHRoZQor bm9uZXhpc3RlbnQgZGF0ZSBGZWJydWFyeSAyOSwgMjEwMDsgYW5kIGFkZGluZyBvbmUgaG91 ciB0byAwMTozMCBvbgorTWFyY2ggMTMsIDIwMjIgaW4gTmV3IFlvcmsgd291bGQgeWllbGQg YSB0aW1lc3RhbXAgMDI6MzAgdGhhdCBkb2VzIG5vdAorZXhpc3QgYmVjYXVzZSBjbG9ja3Mg c3ByYW5nIGZvcndhcmQgZnJvbSAwMjowMCB0byAwMzowMCB0aGF0IGRheS4KK1RvIGF2b2lk IHNvbWUgKHRob3VnaCBub3QgYWxsKSBvZiB0aGUgcHJvYmxlbSwgeW91CiBjYW4gYmFzZSBj YWxjdWxhdGlvbnMgb24gdGhlIG1pZGRsZSBvZiB0aGUgYWZmZWN0ZWQgdW5pdCwgZS5nLiwg c3RhcnQKLWF0IEp1bHkgMSB3aGVuIGFkZGluZyB5ZWFycy4gIEFsdGVybmF0aXZlbHksIHlv dSBjYW4gdXNlIHRoZQorYXQgdGhlIDE1dGggb2YgdGhlIG1vbnRoIHdoZW4gYWRkaW5nIG1v bnRocy4gIEFsdGVybmF0aXZlbHksIHlvdSBjYW4gdXNlIHRoZQogQGZpbGV7Y2FsZW5kYXJ9 IGFuZCBAZmlsZXt0aW1lLWRhdGV9IGxpYnJhcmllcy4KIEBlbmQgZGVmdW4KIAotLSAKMi4z Mi4wCgo= --------------s60V0Pd46BU99QesSH0ZmI3j--