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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,2b151131f90050ab X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-10-29 06:18:20 PST Path: archiver1.google.com!news1.google.com!sn-xit-02!supernews.com!newsfeed.direct.ca!look.ca!newshub2.rdc1.sfba.home.com!news.home.com!news2.rdc2.tx.home.com.POSTED!not-for-mail Message-ID: <3BDD6550.8020805@acm.org> From: Corey Minyard User-Agent: Mozilla/5.0 (X11; U; Linux ppc; en-US; rv:0.9.5+) Gecko/20011012 X-Accept-Language: en-us MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Ada, calendar, and daylight savings References: <3BDCEEFF.10409@acm.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 29 Oct 2001 14:18:20 GMT NNTP-Posting-Host: 24.7.109.109 X-Complaints-To: abuse@home.net X-Trace: news2.rdc2.tx.home.com 1004365100 24.7.109.109 (Mon, 29 Oct 2001 06:18:20 PST) NNTP-Posting-Date: Mon, 29 Oct 2001 06:18:20 PST Organization: Excite@Home - The Leader in Broadband http://home.com/faster Xref: archiver1.google.com comp.lang.ada:15345 Date: 2001-10-29T14:18:20+00:00 List-Id: Larry Kilgallen wrote: > In article <3BDCEEFF.10409@acm.org>, Corey Minyard writes: > >>I won't argue about the goofiness of our time system, since I can't do >>anything about that :-). >> >>Hopefully, missiles in flight are using UTC. It makes no sense to use >>anything else. However, you have no portable way of finding UTC in Ada. >> > > Just ask for the time to be returned. > > If your computer happens to be set to some unreliable source, > such as my watch, then you are at _least_ 5 minutes off from > _anybody's_ notion of time. That is no longer a programming problem. > You are correct, this is a system-level problem, not a programming language problem. But it's relatively easy to solve to a pretty accurate level. > > Please don't burden Ada.Calendar with illogical constructs. I don't agree with this. Suppose I can build a system that has time reasonably coordinated between various parts of the system. "Reasonable" means "It's good enough for the application". It's not unreasonable to do this, I have done it many times, and I still can't use standard Ada to take advantage of this. I could give thousands of examples, but I'll just give one. I used to work on telephony systems, and for billing purposes, you should report UTC time, or some standard time, because the subscriber may not even be in the same timezone as the switch, and switches are generally in different timezones and need to have their records coordinated. Yet you generally want to report logs in local time and UTC time so the operators in the office can make sense of the logs and machines can coordinate logs easily. How are you going to do this in Ada? You can't without using non-standard constructs. Ok, I'll give another. In the previous missile example, suppose the missile is communicating with satellites to maintain it's position. It better be able to tell what time the satellites and ground stations are using and coordinate this with its time. In distributed real-time systems, it's generally important to have some level of time coordination between system elements. -Corey