Re: require-hard-newlines to use newline

[Chong Yidong]

>     As I see it, the rationale for turning on require-final-newline is
>     that a particular type of file should always end in a newline. The
>     user should type RET himself, but in case he forgets to do so, Emacs
>     does it for him. So (newline) should be used.
>
> That is true.  But those kinds of files are in special formats, not
> human-language text.  What is the motive for setting use-hard-newlines
> in one of those buffers?

Require-final-newline is a user option, and if a user customizes it to t
then it is turned on for every buffer, even for human-language text. A
user might do this if he want every file he edits to end in a newline.

>     The specific problem I am trying to solve is with Longlines mode
>     (which is not part of Emacs.) It is, in principle, impossible for
>     Longlines to distinguish between the soft newline inserted by
>     require-final-newline and the soft newline inserted by filling when
>     performing automatic line wrapping.
>
> "Automatic line wrapping" is not a normal Emacs term, and I am not
> sure what you mean by it.  Do you mean Auto Fill mode?  If so,
> longlines can distinguish the two cases because the newline inserted
> by Auto Fill mode is not at the end of the line.
>
> If it means something else, could you please say what?

Like Emacs' built-in Refill mode, Longlines does filling after every user
command, except that it uses its own filling functions (for various
reasons that have to do with simulating the behavior of "word-wrapped"
text editors.) In any case, it makes use of use-hard-newlines to keep
track of hard and soft newlines.

It is impossible to distinguish between a soft newline left at the end of
a line by require-final-newline, and a soft newline produced by, e.g., a
call to kill-line, simply by looking at the context. Both are soft, and
both occur at the end of a line. Both newlines might even occur at the end
of a buffer, if that was the final line. But the first is conceptually a
hard newline, and should not be converted into a space by filling; whereas
the second is a "real" soft newline.