Re: coding-system for drafts

[kai.grossjohann@uni-duisburg.de (Kai Großjohann)]

TSUCHIYA Masatoshi <tsuchiya@namazu.org> writes:

> I think that your solution consists of two parts:
>
>   (1) A new draft which has a coding cookie is decoded in the coding
>       system specified in its cookie.
>   (2) An old draft which lacks a coding cookie is decoded in the value
>       of message-draft-coding-system.

That's right.  There is also the encoding part, though.  I don't have
an opinion which coding system should be used for new drafts (but the
safe iso-2022-7bit seems good), but whatever is chosen should be put
in the coding cookie so that subsequent readings of the file with do
the right thing.

> In this solution, the default value of message-draft-coding-system
> will be stayed in order to keep backwards compatibility.  Do I have a
> proper understanding?

Well, for new auto-save files a different encoding can be chosen.
Only the encoding for reading the old auto-save files must remain the
same.

Silly me, I thought that one could just hard-code `emacs-mule' as the
encoding for reading old files, but that would break if people have
changed message-draft-coding-system.  As you can see, I haven't
thought about it very thoroughly.

> Mr. Yamaoka and I think that emacs-mule is not suitable for the
> default value of message-draft-coding-system.  The main ground of our
> argument is that emacs-mule is not compatible between emacsen.  For
> example,
>
>   (a) emacs-mule is not compatible between Emacs20 and Emacs21,
>       because some charsets are supported by Emacs21 but are not
>       supported by Emacs20.
>   (b) emacs-mule is not compatible between Emacs20 with Mule-UCS and
>       Emacs20 without Mule-UCS.  Charsets related to Unicode are not
>       defined in Emacs20 without Mule-UCS.
>   (c) Because XEmacs does not have emacs-mule coding system, drafts
>       which are written under FSF Emacs are not readable with XEmacs.
>
> Therefore, we think that it is necessary to change the default value
> of message-draft-coding-system from emacs-mule to a coding system
> which is compatible between emacsen and can be used to encode
> multilingual text safely, such as iso-2022-7bit.

I agree that new files should be written using that encoding.

It does not mean that message-draft-coding-system must the variable to
do this.  Maybe we could make that variable obsolete and use a new
one.

> Unfortunately, once the default value of message-draft-coding-system
> is changed to iso-2022-7bit, old drafts encoded in emacs-mule will not
> be decoded correctly.  The trick described by Mr. Yamaoka is designed
> to solve this problem.

Right.  It's a good trick, I think.

Now I understand that we have been talking about different problems.
That explains our misunderstandings :-)

> Could you tell me how coding cookie solves this problem?

The coding cookie does not deal with old files, only with new files.
So the coding cookie is not a solution to the problem solved by
Yamaoka-san.

> It is true that we could safely change the default value of
> message-draft-coding-system, if coding cookie was introduced.

If it wasn't for the old files, we could...

kai
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