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From: Kenichi Handa <handa@m17n.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Inconsistencies regarding nil coding-system
Date: Mon, 13 Dec 2010 16:45:53 +0900	[thread overview]
Message-ID: <tl7r5dm15fy.fsf@m17n.org> (raw)
In-Reply-To: <83aakcvbtp.fsf@gnu.org> (message from Eli Zaretskii on Sat, 11 Dec 2010 12:33:06 +0200)

In article <83aakcvbtp.fsf@gnu.org>, Eli Zaretskii <eliz@gnu.org> writes:

>   (coding-system-change-eol-conversion nil 'unix) => nil
>   (coding-system-change-text-conversion 'latin-1-dos nil) => undecided-dos
>   (coding-system-base nil) => no-conversion

> When primitives that encode/decode text accept nil as their
> coding-system argument, they use `undecided' (AFAIK).  So the second
> result above looks reasonable, but the first and the last are
> inconsistent, and the last one is downright surprising.

> Any reasons not to change coding-system-change-eol-conversion and
> coding-system-base to consistently treat nil as `undecided'?  (If
> agreed to, I suggest to make this change only on the trunk, not on the
> release branch.)

When I first introduced coding-system, nil was for
no-conversion, and t was for undecided, and as time passed,
we have shifted to `no-conversion' and `undecided'.  But,
some old codes still treat nil for `no-conversion' and new
codes consider nil as "unspecified" and thus treat it as
`undecided'.  Perhaps, ver. 24 is a good timing to wipe out
this confusion, but I'm not sure how to treat nil.  Nil
should usually mean "unspecified", and what exactly
"unspecified" means depends on a situaion.

---
Kenichi Handa
handa@m17n.org



  reply	other threads:[~2010-12-13  7:45 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-11 10:33 Inconsistencies regarding nil coding-system Eli Zaretskii
2010-12-13  7:45 ` Kenichi Handa [this message]
2010-12-13 14:58   ` Eli Zaretskii
2010-12-14  1:41     ` Kenichi Handa
2010-12-14  4:00       ` Eli Zaretskii
2010-12-14  4:40         ` Kenichi Handa
2010-12-14  7:44           ` Kenichi Handa
2010-12-14  9:25             ` Eli Zaretskii
2010-12-14 11:03               ` Kenichi Handa
  -- strict thread matches above, loose matches on Subject: below --
2010-12-11 10:33 Eli Zaretskii

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