From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.4 required=5.0 tests=AC_FROM_MANY_DOTS,BAYES_00 autolearn=no autolearn_force=no version=3.4.4 X-Google-Thread: 103376,ee78aab9bfd2fe2a X-Google-Attributes: gid103376,domainid0,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Wilhelm Spickermann Newsgroups: comp.lang.ada Subject: Re: Inspiration for a better calendar package? Date: Mon, 15 Dec 2008 13:59:02 +0100 Message-ID: <6qn2kmFdflp2U1@mid.individual.net> References: <873agxd6i1.fsf@nbi.dk> <12gqldae49yoe$.1sf2zlz1fthvh.dlg@40tude.net> <6qmg8dFd8kd2U1@mid.individual.net> <1jv16tgrmhor4$.c3a8ugjxu6ed$.dlg@40tude.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7Bit X-Trace: individual.net 7AwDStXiT62CWYjJYe7V6AX4EITNih5+sIdwB2YuKOmreTxvA8 Cancel-Lock: sha1:SGY5CFdais10asmF1Gs0/1TjxtI= Xref: g2news1.google.com comp.lang.ada:2992 Date: 2008-12-15T13:59:02+01:00 List-Id: Dmitry A. Kazakov wrote: >> The second one is a wall clock time with the smallest unit >> being a minute on the wall clock (thus having 59, 60 or 61 >> seconds length). We can define an arithmetic here and it is >> used to specify times related to human activities. This time >> is used to store dates like "second monday after easter 2014 >> at 10:00 UTC" or "every day at 12:00 UTC". > > Why cannot you use UTC instead? Political time is a combination > of UTC time and the time zone. The latter is a function that > yields the time offset for each given UTC time value. Yes you > could skew the resolution down to the point where any > differences become invisible. What about one year? (:-)) The > question what this thing could be used for? Well, I can add 900_000_000 seconds to "now" in the first kind of time I mentioned. Then we will have a clearly specified point in time resulting, which we could very well use, to start some process. But we cannot convert it to UTC, as we do not know all the leap second rules of the future. On the other hand, we can make an appointment for the 17-aug-2023, 10:00 UTC and this is also a somehow clearly specified point in time, as we would be able to meet at that time. But no one is able to convert this specification to a "real time" now. (That's why I refuse to call it UTC.) The resolution of "one nominial minute" (_not_ a physical unit) for wall clock time was chosen, because it's the finest usable resultion. We can tell that we have 4 nominal minutes between 31-dec-2044 23:59:58 and 01-jan-2045 00:00:02. But we cannot express this difference in seconds (or in the physical unit "one minute"). We will hopefully be able to do that in summer 2044 or perhaps earlier, when the leap seconds are eliminated. Wilhelm