From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Emacs 23 character code space Date: Sat, 29 Nov 2008 19:12:46 +0200 Message-ID: References: Reply-To: Eli Zaretskii NNTP-Posting-Host: lo.gmane.org X-Trace: ger.gmane.org 1227978774 16156 80.91.229.12 (29 Nov 2008 17:12:54 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 29 Nov 2008 17:12:54 +0000 (UTC) Cc: emacs-devel@gnu.org To: Kenichi Handa Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Nov 29 18:13:58 2008 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1L6TOH-0000By-9g for ged-emacs-devel@m.gmane.org; Sat, 29 Nov 2008 18:13:57 +0100 Original-Received: from localhost ([127.0.0.1]:57136 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1L6TN6-0000iN-Vt for ged-emacs-devel@m.gmane.org; Sat, 29 Nov 2008 12:12:45 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1L6TN1-0000g2-Uv for emacs-devel@gnu.org; Sat, 29 Nov 2008 12:12:39 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1L6TN1-0000fn-3Q for emacs-devel@gnu.org; Sat, 29 Nov 2008 12:12:39 -0500 Original-Received: from [199.232.76.173] (port=45988 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1L6TN1-0000fk-0g for emacs-devel@gnu.org; Sat, 29 Nov 2008 12:12:39 -0500 Original-Received: from mtaout6.012.net.il ([84.95.2.16]:43954) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1L6TN0-0003zc-LC for emacs-devel@gnu.org; Sat, 29 Nov 2008 12:12:38 -0500 Original-Received: from conversion-daemon.i-mtaout6.012.net.il by i-mtaout6.012.net.il (HyperSendmail v2007.08) id <0KB300B00UJ3HG00@i-mtaout6.012.net.il> for emacs-devel@gnu.org; Sat, 29 Nov 2008 19:14:45 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([77.127.156.55]) by i-mtaout6.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0KB300DMRUKISB80@i-mtaout6.012.net.il>; Sat, 29 Nov 2008 19:14:43 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by monty-python.gnu.org: Solaris 10 (1203?) 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:106308 Archived-At: > From: Kenichi Handa > CC: emacs-devel@gnu.org > Date: Thu, 27 Nov 2008 10:29:50 +0900 > > To convert between a character sequence and a byte sequence, > Emacs actually does two steps of conversions as below. > > > characters --(1)-> (charset code-point) pairs --(3)-> bytes > <-(2)-- <-(4)-- > > For the encoding of (1), Emacs uses infomaiton of coding > system to decide which charset to use, and then uses > informaiton of the selected charset to get a code point. > For the decoding of (2), Emacs uses informaiton of charset > to get character codes. > > For the encoding of (3) and the decoding of (4), Emacs uses > only information of coding system. Thanks. However, does this two-step procedure make a difference for a Lisp programmer? It sounds like this is an internal implementation detail that happens transparently, so Lisp programmers shouldn't care about it. My original confusion was about when character sets are exposed to Lisp application programs. I understand that one situation is when Emacs displays a character with some font. Are there other situations?