bug#39517: [PATCH] Add new option 'word-wrap-boundary'

[Jaehwang Jerry Jung]

On 11/02/2020 01:10, Eli Zaretskii wrote:
> > From: Jaehwang Jerry Jung <tomtomjhj@gmail.com>
> > Cc: 39517@debbugs.gnu.org
> > Date: Tue, 11 Feb 2020 00:36:01 +0900
> >
> > I noticed that word wrapping looks a bit weird when the text contains
> > long URLs.  So I wanted to add non-word ASCII characters so that URLs
> > can be wrapped more naturally as in other editors, while not changing
> > the default behavior.
> OK, but is that the only relevant use case?  Maybe we have others.  We
> need to think in more general terms, in case the other use cases might
> suggest different solutions.

Not that I know of.

> > -  ((it->what == IT_CHARACTER && (it->c == ' ' || it->c == '\t'))      \
> > +#define IT_DISPLAYING_WORD_WRAP_BOUNDARY(it)                           \
> > +  ((it->what == IT_CHARACTER                                                \
> > +    && strchr ((char *) SDATA (BVAR (current_buffer, word_wrap_boundary)), \
> > +               it->c))                                                      \
> >
> > This cannot be right: characters are stored in Lisp strings in a
> > multibyte encoding that is superset of UTF-8, so the above will only
> > support pure-ASCII boundary characters, which is probably not what you
> > had in mind.
> >
> > You're right. Actually I think it would be simpler to hard-code a better
> > list of boundary characters in that macro.
> I don't think we can hardcode them, because the set of characters must
> be buffer-local: we don't want to wrap on '/' in a general text-mode
> buffer, let alone in a C-mode buffer, right?

It's not uncommon to wrap on '/'. For example,
* Vim: http://vimdoc.sourceforge.net/htmldoc/options.html#'breakat'
* Visual Studio Code: 
https://github.com/microsoft/vscode/blob/39370d9c988c584fa2e834728d8ffa56259ff1ad/src/vs/editor/common/config/editorOptions.ts#L279-L283

Anyway, I agree with configurability. Perhaps I'll need some more time
to implement it with multibyte characters in mind. Or we could use the
syntax table.

> >   Last, but not least, for a contribution this large, we will need you
> > to assign the copyright to the FSF.  If you agree, I will send you the
> > form to fill and the instructions to send it.
> >
> > Yes, I agree.
> Form sent off-list.
>
> Thanks.

Thanks. I sent the request.