Re: detecting encoding for Japanese

[Katsumi Yamaoka <yamaoka@jpl.org>]

>>>>> In <vaf8z2k8fj0.fsf@INBOX.auto.gnus.tok.lucy.cs.uni-dortmund.de>
>>>>>	Kai.Grossjohann@CS.Uni-Dortmund.DE (Kai Großjohann) wrote:

[...]

Kai> Okay.  So it seems that Japanese users always want what you are
Kai> saying.

Kai> What do you think about changing the default value to the
Kai> following expression?

Kai> (when (string= current-language-environment "Japanese")
Kai> '(iso-2022-jp iso-2022-jp-2 japanese-shift-jis utf-8))

Kai> We could add a comment saying that we still need to investigate
Kai> which values are good for other language environments.

That's good.

Kai> But I wonder if there is a right way to do this?  The right way,
Kai> IMHO, would be to use the standard coding system priorities in
Kai> principle, except that they are slightly modified to prefer
Kai> iso-2022-jp over euc-jp.  Hm.  "emacs -q -no-site-file", then
Kai> setting the Japanese language environment, tells me:

Kai>| Priority order for recognizing coding systems when reading
Kai>| files: 1. iso-2022-jp (alias: junet)
Kai>| 2. japanese-iso-8bit (alias: euc-japan-1990 euc-japan euc-jp)
Kai>| 3. japanese-shift-jis (alias: shift_jis sjis)
Kai>| 4. iso-2022-jp-2
Kai>| 5. iso-latin-1 (alias: iso-8859-1 latin-1)

[...]

Although surely it becomes so in almost systems, please see the
function `setup-japanese-environment-internal' doing:

(defun setup-japanese-environment-internal ()
  (cond ((eq system-type 'ms-dos)
	 (prefer-coding-system 'japanese-shift-jis))
	((eq system-type 'usg-unix-v)
	 (prefer-coding-system 'japanese-iso-8bit)))
  [...])

This is defined in language/japan-util.el and which will be
called from `(set-language-environment "Japanese")'.  Because of
this, the coding priority in Solaris will be the order of:

(mapcar 'symbol-value coding-category-list)
 => (japanese-iso-8bit iso-2022-jp japanese-shift-jis
     iso-2022-jp-2 iso-latin-1 iso-2022-7bit iso-2022-8bit-ss2
     emacs-mule raw-text chinese-big5 nil no-conversion ...)

I do not know whether only `usg-unix-v' is special, though.
-- 
Katsumi Yamaoka <yamaoka@jpl.org>