From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Kenichi Handa Newsgroups: gmane.emacs.devel Subject: Re: Coding system robustness? Date: Sat, 19 Mar 2005 10:08:16 +0900 (JST) Message-ID: <200503190108.KAA22411@etlken.m17n.org> References: <87wts43jxx.fsf-monnier+emacs@gnu.org> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 (generated by SEMI 1.14.3 - "Ushinoya") Content-Type: text/plain; charset=US-ASCII X-Trace: sea.gmane.org 1111195895 26029 80.91.229.2 (19 Mar 2005 01:31:35 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Sat, 19 Mar 2005 01:31:35 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Mar 19 02:31:35 2005 Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DCSoJ-00043E-2I for ged-emacs-devel@m.gmane.org; Sat, 19 Mar 2005 02:31:27 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DCT4u-0003Zc-3r for ged-emacs-devel@m.gmane.org; Fri, 18 Mar 2005 20:48:36 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1DCT43-0003Fs-LU for emacs-devel@gnu.org; Fri, 18 Mar 2005 20:47:52 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DCT3x-0003DO-Q2 for emacs-devel@gnu.org; Fri, 18 Mar 2005 20:47:39 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DCT3x-0003DC-KO for emacs-devel@gnu.org; Fri, 18 Mar 2005 20:47:37 -0500 Original-Received: from [192.47.44.130] (helo=tsukuba.m17n.org) by monty-python.gnu.org with esmtp (TLSv1:DES-CBC3-SHA:168) (Exim 4.34) id 1DCSRw-00057R-FH; Fri, 18 Mar 2005 20:08:21 -0500 Original-Received: from nfs.m17n.org (nfs.m17n.org [192.47.44.7]) by tsukuba.m17n.org (8.12.3/8.12.3/Debian-7.1) with ESMTP id j2J18HdY009997; Sat, 19 Mar 2005 10:08:18 +0900 Original-Received: from etlken.m17n.org (etlken.m17n.org [192.47.44.125]) by nfs.m17n.org (8.12.3/8.12.3/Debian-7.1) with ESMTP id j2J18GDI031644; Sat, 19 Mar 2005 10:08:16 +0900 Original-Received: (from handa@localhost) by etlken.m17n.org (8.8.8+Sun/3.7W-2001040620) id KAA22411; Sat, 19 Mar 2005 10:08:16 +0900 (JST) Original-To: Stefan Monnier In-reply-to: <87wts43jxx.fsf-monnier+emacs@gnu.org> (message from Stefan Monnier on Fri, 18 Mar 2005 13:11:43 -0500) User-Agent: SEMI/1.14.3 (Ushinoya) FLIM/1.14.2 (Yagi-Nishiguchi) APEL/10.2 Emacs/21.3.50 (sparc-sun-solaris2.6) MULE/5.0 (SAKAKI) 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 X-MailScanner-To: ged-emacs-devel@m.gmane.org Xref: news.gmane.org gmane.emacs.devel:34756 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:34756 In article <87wts43jxx.fsf-monnier+emacs@gnu.org>, Stefan Monnier writes: >> I'd like to know whether coding systems in general are supposed to be >> robust, meaning that decoding some random byte string into the coding >> system and reencoding it is guaranteed to deliver the same byte string >> again? > AFAIK, (encode-coding-string (decode-coding-string STR 'foo) 'foo) > should always return STR, otherwise it's a bug. > With the introduction of eight-bit-*, this should be true of "all" > coding-systems in Emacs-21, No. Redundant escape sequences in iso-2022 based coding systems are just ignored. For instance, (decode-coding-string "\e(J" 'iso-2022-jp) => "" And we can't recover "\e(J" on encoding. --- Ken'ichi HANDA handa@m17n.org