Re: Cyrillic vs UTF-8

[Stefan Monnier]

> > > Maybe it is.  In my situation, I'd like utf-8 to be at the top
> > > of the preferences w.r.t decoding because it virtually never
> > > guesses wrong.
> > > OTOH, I'm still using a mostly-latin-1 environment, so I'd
> > > still rather avoid utf-8 when I can.  I.e. latin-1 should be at
> > > the top of my preferences w.r.t encoding.
> > 
> > In that case, I think the source of the problem is that the
> > command prefer-coding-system doesn't satisfy this request of
> > yours:
> >    Prefer utf-8 only in automatic detection on reading a
> >    file, not for the other situations.
> > 
> > (defun prefer-coding-system (coding-system)
> >   "Add CODING-SYSTEM at the front of the priority list for automatic 
> > detection.
> > This also sets the following coding systems:
> >   o coding system of a newly created buffer
> >   o default coding system for subprocess I/O
> > This also sets the following values:
> >   o default value used as `file-name-coding-system' for converting file 
> > names.
> >   o default value for the command `set-terminal-coding-system' (not on 
> > MSDOS)
> >   o default value for the command `set-keyboard-coding-system'
> > 
> > How about changing it to skip "This also ..." parts if
> > called with a prefix argument?
> > 
> > Then, on writing, if buffer-file-coding-system is not
> > locally bound, default-buffer-file-coding-system is tried
> > automatically.
> > 
> > And, for the case that buffer-file-coding-system is locally
> > bound differently from default-buffer-file-coding-system,
> > but it can'd encode the current buffer, we can change
> > select-safe-coding-system to try
> > default-buffer-file-coding-system before trying the most
> > preferred coding system.
> > 
> > That way, I think we can satisfy your request completely.
> 
> That seems like a cheap way to get what I want indeed.

Actually I don't currently use prefer-coding-system (specifically
because I didn't want to set all those other coding-systems),
instead I use

(when (boundp 'coding-category-utf-8)
  (set-coding-priority '(coding-category-utf-8)))

so I guess the only change that I care about is the part that uses
default-buffer-file-coding-system in preference to the most preferred
coding system (although it does sound paradoxical ;-)

The patch below would work for me; any comment/objection ?


        Stefan


Index: mule-cmds.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/international/mule-cmds.el,v
retrieving revision 1.231
diff -u -u -b -r1.231 mule-cmds.el
--- mule-cmds.el        16 May 2003 04:15:20 -0000      1.231
+++ mule-cmds.el        19 May 2003 13:45:16 -0000
@@ -1,5 +1,5 @@
 ;;; mule-cmds.el --- commands for mulitilingual environment
-;; Copyright (C) 1995 Electrotechnical Laboratory, JAPAN.
+;; Copyright (C) 1995, 2003 Electrotechnical Laboratory, JAPAN.
 ;; Licensed to the Free Software Foundation.
 ;; Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
 
@@ -631,7 +631,8 @@
 between FROM and TO are shown in a popup window.  Among them, the most
 proper one is suggested as the default.
 
-The list of `buffer-file-coding-system' of the current buffer and the
+The list of `buffer-file-coding-system' of the current buffer,
+the `default-buffer-file-coding-system', and the
 most preferred coding system (if it corresponds to a MIME charset) is
 treated as the default coding system list.  Among them, the first one
 that safely encodes the text is normally selected silently and
@@ -648,8 +649,8 @@
 list of coding systems to be prepended to the default coding system
 list.  However, if DEFAULT-CODING-SYSTEM is a list and the first
 element is t, the cdr part is used as the defualt coding system list,
-i.e. `buffer-file-coding-system' and the most prepended coding system
-is not used.
+i.e. `buffer-file-coding-system', `default-buffer-file-coding-system',
+and the most preferred coding system are not used.
 
 Optional 4th arg ACCEPT-DEFAULT-P, if non-nil, is a function to
 determine the acceptability of the silently selected coding system.
@@ -679,6 +680,9 @@
          (mapcar (function (lambda (x) (cons x (coding-system-base x))))
                  default-coding-system))
 
+    ;; From now on, the list of defaults is reversed.
+    (setq default-coding-system (nreverse default-coding-system))
+
     (unless no-other-defaults
       ;; If buffer-file-coding-system is not nil nor undecided, append it
       ;; to the defaults.
@@ -686,24 +690,30 @@
          (let ((base (coding-system-base buffer-file-coding-system)))
            (or (eq base 'undecided)
                (rassq base default-coding-system)
-               (setq default-coding-system
-                     (append default-coding-system
-                             (list (cons buffer-file-coding-system base)))))))
+               (push (cons buffer-file-coding-system base)
+                     default-coding-system))))
+
+      ;; If default-buffer-file-coding-system is not nil nor undecided,
+      ;; append it to the defaults.
+      (if default-buffer-file-coding-system
+         (let ((base (coding-system-base default-buffer-file-coding-system)))
+           (or (eq base 'undecided)
+               (rassq base default-coding-system)
+               (push (cons default-buffer-file-coding-system base)
+                     default-coding-system))))
 
       ;; If the most preferred coding system has the property mime-charset,
       ;; append it to the defaults.
       (let ((tail coding-category-list)
            preferred base)
-       (while (and tail
-                   (not (setq preferred (symbol-value (car tail)))))
+       (while (and tail (not (setq preferred (symbol-value (car tail)))))
          (setq tail (cdr tail)))
        (and (coding-system-p preferred)
             (setq base (coding-system-base preferred))
             (coding-system-get preferred 'mime-charset)
             (not (rassq base default-coding-system))
-            (setq default-coding-system
-                  (append default-coding-system
-                          (list (cons preferred base))))))))
+            (push (cons preferred base)
+                  default-coding-system)))))
 
   (if select-safe-coding-system-accept-default-p
       (setq accept-default-p select-safe-coding-system-accept-default-p))
@@ -724,7 +734,7 @@
              (push (car elt) safe))
          (push (car elt) unsafe)))
       (if safe
-         (setq coding-system (car (last safe)))))
+         (setq coding-system (car safe))))
 
     ;; If all the defaults failed, ask a user.
     (when (not coding-system)