Re: detect big5, utf8, gb2312 as good as firefox

[Kevin Rodgers]

Dan Jacobson wrote:
> Gentlemen, with three plain text files of coded in my most commonly
> encountered coding systems, I did this test:
> $ for c in zh_CN.gb2312 zh_TW.utf8 zh_TW.big5;
> do LC_CTYPE=$c LANG=$c LC_ALL=$c emacs -q gb2312 utf8 big5; done
> Well, zh_CN.gb2312 guessed right each time!
> With zh_TW.utf8, emacs guessed the big5 and gb files were latin-1, as
> seen by the 1 in the modeline and the jumble on the screen.
> With zh_TW.big5, the gb2312 file was seen jumbled as type big5.
> In .emacs I can do
> (set-language-environment "UTF-8")
> (prefer-coding-system 'utf-8-unix)
> (set-coding-priority ;So that big5 is still guessed right after utf-8.
>  (reverse ;Found these lisp thingies and it works.
>   (delete-duplicates
>    (reverse;no lisp pro me
>     (append(list 'coding-category-utf-8
>                  'coding-category-big5)coding-category-list)))))
> to detect all but gb2312 OK. What should I do, make my whole
> environment CN even though I only visit those kind of files once a
> week, and plan to live in UTF-8 / big5 land ... BTW, firefox guessed
> right each time even though they were plain text files with no
> charset= hints.

I would instead try this first:

;; From least- to most-preferred:
(prefer-coding-system 'gb2312)
(prefer-coding-system 'big5)
(prefer-coding-system 'utf-8)

If you insist on frobbing coding-category-list:

(set-coding-priority
 ;; Insert big5 after utf-8:
 (apply 'nconc
        (mapcar (lambda (coding-category)
                  (if (eq coding-category 'coding-category-utf-8)
                      (list 'coding-category-utf-8 'coding-category-big5)
                    (list coding-category)))
                coding-category-list)))

Note that you can replace (apply 'nconc (mapcar ...)) with
(require 'cl)(mapcan ...)

Do you get better or worse results with those approaches?

--
Kevin Rodgers