Re: mm-with-unibyte-current-buffer

[Eli Zaretskii <eliz@gnu.org>]

> Date: Mon, 10 May 2010 16:26:29 +0900
> From: Katsumi Yamaoka <yamaoka@jpl.org>
> Cc: emacs-devel@gnu.org
> 
> I've redefined the `mm-with-unibyte-current-buffer' macro so as
> not to bind the default value of `enable-multibyte-characters' to
> nil, since it is no longer allowed (causes an error actually) in
> Emacs 24.  Formerly it did in a multibyte buffer:
> 
> (letf (((default-value 'enable-multibyte-characters) nil))
>   (set-buffer-multibyte nil)
>   bla bla bla
>   (set-buffer-multibyte t))
> 
> Now it only does:
> 
>   (set-buffer-multibyte nil)
>   bla bla bla
>   (set-buffer-multibyte t)

Binding the value of enable-multibyte-characters may be a no-no, but
_testing_ its value is still possible.  So I see no reason to
set-buffer-multibyte unconditionally, because you may already be in a
unibyte buffer.

> Anyway changing the multibyteness of a buffer may cause a serious
> trouble to buffer's contents especially if there are multibyte or
> 8-bit characters.

Like what?  I thought we are way past this kind of trouble in Emacs 23.