From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: does Calendar understand DST rules for past years? Date: Thu, 21 Dec 2006 13:06:47 -0500 Message-ID: Reply-To: rms@gnu.org NNTP-Posting-Host: dough.gmane.org Content-Type: text/plain; charset=ISO-8859-15 X-Trace: sea.gmane.org 1166980484 9666 80.91.229.10 (24 Dec 2006 17:14:44 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Sun, 24 Dec 2006 17:14:44 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Dec 24 18:14:43 2006 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by dough.gmane.org with esmtp (Exim 4.50) id 1GyWvo-0005e4-LW for ged-emacs-devel@m.gmane.org; Sun, 24 Dec 2006 18:14:40 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GyWvo-00026C-1e for ged-emacs-devel@m.gmane.org; Sun, 24 Dec 2006 12:14:40 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1GyWrH-0004JS-8k for emacs-devel@gnu.org; Sun, 24 Dec 2006 12:09:59 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1GyWrG-0004Hf-AZ for emacs-devel@gnu.org; Sun, 24 Dec 2006 12:09:58 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1GyWrG-0004HT-1l for emacs-devel@gnu.org; Sun, 24 Dec 2006 12:09:58 -0500 Original-Received: from [199.232.76.164] (helo=fencepost.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.52) id 1GyWrF-0006fS-Q5 for emacs-devel@gnu.org; Sun, 24 Dec 2006 12:09:57 -0500 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.60) (envelope-from ) id 1GyWr8-0002YX-VC; Sun, 24 Dec 2006 12:09:51 -0500 Original-To: rgm@gnu.org X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:64213 Archived-At: I asked Glenn Morris to look at this, but since he is away for a couple of weeks, I ask if anyone else can figure out what is right here. man/calendar.el says The dates used by Emacs for holidays are based on @emph{current practice}, not historical fact. Historically, for instance, the start of daylight savings time and even its existence have varied from year to year, but present United States law mandates that daylight savings time begins on the first Sunday in April. When the daylight savings rules are set up for the United States, Emacs always uses the present definition, even though it is wrong for some prior years. but the code seems to test calendar-dst-check-each-year-flag, which is normally true. I do not understand the code which that calls; it needs a lot more comments. Can you please add comments? But I can't see any sense in checking each year unless there is a facility for recording the changes in rules between years. In that case, the drawback which is documented is not reallky true.