Re: Emacs-diffs Digest, Vol 2, Issue 28

[Kenichi Handa <handa@m17n.org>]

In article <E18Zh9W-00012L-00@fencepost.gnu.org>, Richard Stallman <rms@gnu.org> writes:

>     ! The string argument is normally a multibyte string, except:
>     ! - if the process' input coding system is no-conversion or raw-text,
>     !   it is a unibyte string (the non-converted input), or else

> Is this really the right way for it to work?
> Should the choice of unibyte or multibyte string
> be tied in this way to the choice of coding system?

This facility was added upon someone's request or to fix
some problem long ago.

1998-12-21  Kenichi Handa  <handa@etl.go.jp>
[...]
	* process.c (read_process_output): Decide the multibyteness of
	string given to a process filter by a coding system used for
	decoding the process output.

But, I don't remeber the detail now.

> If you want multibyte strings "without decoding", would emacs-mule
> give you that?

It depends on what kind of multibyte string we want.

If we want the same result as reading a file containing the
same byte sequence by emacs-mule, emacs-mule is fine.   This
is the same as reading by no-converson, and insert the given
unibyte string by:
  (insert (string-as-multibyte UNIBYTE-STRING)).

If we want a multibyte sequence that is the same as the
result of converting each of the original bytes by
unibyte-char-to-multibyte, we must read by no-conversion,
and insert the given unibyte string just by `insert':
  (insert UNIBYTE-STRING)
This is the same as doing:
  (insert (string-make-multibyte UNIBYTE-STRING))

If we want a multibyte sequence but each character contained
is one of ascii, eight-bit-control, and eight-bit-graphic
corresponding to the original bytes, we must read by
no-conversion, and insert characters one by one as below:
  (apply 'insert (string-to-list UNIBYTE-STRING))
Perhaps, we must have a function, say, string-to-multibyte,
and make this enable.
  (insert (string-to-multibyte UNIBYTE-STRING))

---
Ken'ichi HANDA
handa@m17n.org