Re: filling bug in text-mode

[Juri Linkov <juri@jurta.org>]

>     One solution is to fix the regexp in `sentence-end' to match three
>     periods.
>
> I think that is the correct fix, because the sentence commands
> _should_ stop after three periods (when followed by two spaces
> or a newline).

Should the sentence commands stop also after three question marks???
And sentences can also end with three exclamation marks!!!

> It is a bug if they don't stop there.

This depends on the operational semantics of `sentence-end' rather
than its formal definition.  The current value of `sentence-end' allows
the sentence commands to process sentences with three periods correctly
except one place that caused this bug.  The use of `sentence-end' is
very questionable in this place.  Please, look at it again:

     (save-excursion
       (skip-chars-backward ". ")
       (and (looking-at "\\.")
     	    (not (looking-at (sentence-end)))))

Why only periods are skipped and matched by `looking-at' while
sentences can end also with `!' and `?' which are included in
`sentence-end' along with the period?

I'm inclined to fix this place rather than to change the default value
of `sentence-end'.  There are functions like `fill-delete-newlines'
that rely on its current default value, so changing the default value
of `sentence-end' will break such functions.

-- 
Juri Linkov
http://www.jurta.org/emacs/