# HG changeset patch
# User aidan
# Date 1109633792 0
# Node ID c8a9be2d4728fe1d542b2a3be3c684af61d16335
# Parent  a5158a1f89a40e7e6700c2023868a0eecf7b33f5
[xemacs-hg @ 2005-02-28 23:36:30 by aidan]
Add details about losing data to the unicode-to-char docstring.

The Mule character encoding model means that extant Unicode coding systems
will lose data. Make this clear in the docstring of unicode-to-char, give
sample code to implement support for some desired code points should our
distributors want to do that.

diff -r a5158a1f89a4 -r c8a9be2d4728 src/ChangeLog
--- a/src/ChangeLog	Mon Feb 28 22:51:03 2005 +0000
+++ b/src/ChangeLog	Mon Feb 28 23:36:32 2005 +0000
@@ -1,3 +1,11 @@
+2005-03-01  Aidan Kehoe  <kehoea@parhasard.net>
+
+	* unicode.c: The Mule character encoding model means that extant
+	Unicode coding systems will lose data. Make this clear in the
+	docstring of unicode-to-char, give sample code to implement
+	support for some desired code points should our distributors want
+	to do that. 
+
 2005-02-28  Aidan Kehoe  <kehoea@parhasard.net>
 
 	* select-gtk.c (emacs_gtk_selection_handle):
diff -r a5158a1f89a4 -r c8a9be2d4728 src/unicode.c
--- a/src/unicode.c	Mon Feb 28 22:51:03 2005 +0000
+++ b/src/unicode.c	Mon Feb 28 23:36:32 2005 +0000
@@ -1281,6 +1281,38 @@
 When there is no international support (i.e. the 'mule feature is not
 present), this function simply does `int-to-char' and ignores the CHARSETS
 argument.
+
+Note that the current XEmacs internal encoding has no mapping for many
+Unicode code points, and if you use characters that are vaguely obscure with
+XEmacs' Unicode coding systems, you will lose data.
+
+To add support for some desired code point in the short term--note that our
+intention is to move to a Unicode-compatible internal encoding soon, for
+some value of soon--if you are a distributor, add something like the
+following to `site-start.el.'
+
+(make-charset 'distro-name-private 
+	      "Private character set for DISTRO"
+	      '(dimension 1
+		chars 96
+		columns 1
+		final ?5 ;; Change this--see docs for make-charset
+		long-name "Private charset for some Unicode char support."
+		short-name "Distro-Private"))
+
+(set-unicode-conversion 
+ (make-char 'distro-name-private #x20) #x263A) ;; WHITE SMILING FACE
+
+(set-unicode-conversion 
+ (make-char 'distro-name-private #x21) #x3030) ;; WAVY DASH
+
+;; ... 
+;;; Repeat as necessary. 
+
+Redisplay will work on the sjt-xft branch, but not with server-side X11
+fonts as is the default.  However, data read in will be preserved when they
+are written out again.
+
 */
        (code, USED_IF_MULE (charsets)))
 {