Display of em dashes in our documentation

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

> Even if such an option existed, it would still beg the question: how
> to produce the Info manuals we provide as part of the Emacs release
> tarballs?  The downside of any decision in this matter is that it is
> imposed on everyone, no matter what their views on this.

OTOH, they already get the old/readable em dash rendering in many other
GNU manuals.  So perhaps not many people are very invested in the issue?

> So I'd prefer to deal with this differently: introduce a new
> (buffer-local) minor mode, which will install a display-table, whereby
> "problematic" Unicode characters will be displayed as their ASCII
> equivalents or equivalent ASCII strings.  We already set that up
> automatically on terminals that are incapable of displaying those
> characters, but nothing precludes us from having such a feature on
> demand for capable displays as well.  Then users who don't want the
> effects of these characters on display could activate such a mode, and
> solve their problems without affecting the actual contents of the Info
> files.

That's an interesting idea.  So you propose that this minor mode could
display many more problematic Unicode characters in a different way, and
that it would not necessarily be limited to info?

I guess it doesn't take much coding, but the interesting question is
which other Unicode characters it should cover.  I only know about em
dash; are there others?

One drawback is that em dash is only confirmed to be problematic in some
situations; that is when they are written "like—this" with no space in
between, whereas in situations "like — this" I think it is much
preferable to show the actual Unicode character.

Actually, this gives me another way of how we could do it: in our info
manuals, as the final step before displaying it, we do something like
this (here quickly coded up as a hook):

    (defun sk/Info-fix-em-dashes ()
      (save-excursion
        (goto-char (point-min))
        (let ((case-fold-search t)
              (buffer-read-only nil))
          (while (re-search-forward "\\([a-z”’']\\)—\\([a-z]“‘`'\\)" nil t)
            (replace-match "\\1 — \\2" t)))))

    (add-hook 'Info-selection-hook #'sk/Info-fix-em-dashes)

    (info "(emacs) After a Crash")

This could be made optional, or even the default if we agree that it is
more readable than what we have now.

In any monospace font, I certainly prefer this:

       When ‘recover-session’ is done, the files you’ve chosen to recover
    are present in Emacs buffers.  You should then save them.  Only
    this — saving them — updates the files themselves.

To this:

       When ‘recover-session’ is done, the files you’ve chosen to recover
    are present in Emacs buffers.  You should then save them.  Only
    this—saving them—updates the files themselves.

That way, everyone gets readable text but also UTF-8 characters.
Win-win.  Perhaps this is even something the Texinfo developers would be
willing to consider.