Message-ID:  <9604021450.AA25874@r8h.cs.man.ac.uk>
Reply-To: Mailing list for the LaTeX3 project
              <LATEX-L@relay.urz.uni-heidelberg.de>
In-Reply-To:  <199604021335.PAA03506@murnau.idris.fr> (message from Bernard
              GAULLE on Tue, 2 Apr 1996 15:35:14 +0200)
Date:         Tue, 2 Apr 1996 15:50:38 BST
From: David Carlisle <carlisle@CS.MAN.AC.UK>
Sender: Mailing list for the LaTeX3 project
              <LATEX-L@relay.urz.uni-heidelberg.de>
To: Multiple recipients of list LATEX-L
              <LATEX-L@relay.urz.uni-heidelberg.de>
Subject:      Re: Changing \hyphenchar
Status: R

Bernard writes

  I'd like (and all French speaking people with me) a general solution
  be found for LaTeX.

Well this message will not provide a general solution (sorry!) but
anyway some thoughts...


> With the dc, the printed glyph is font slot '177 / ^^7f
> (except with olddc package)

The fd files generated by `olddc.ins' use the dc 1.1 release font
names and the ones generated by `newdc.ins' generate the new release
1.2 names, but in both cases the hyphenchar of the fonts are not set
(except for tt fonts which set it to -1)

(The fd files distributed with the dc fonts do set it, but that is
another issue)

As the hyphenchar is not set when the fonts are loaded, the
\defaulthyphenchar is used, no standard LaTeX package changes this
from its default plain value of 45 (-) and so LaTeX whether using cm
fonts, or new or old dc currently gets French hyphenation right
according to your criteria (and presumably therefore gets it wrong
for other languages).

If someone wants to use the alternative hyphenation character with the
fd files distributed by LaTeX, then more or less they just need to set
\defaulthypenchar to 127 before loading the fonts. Unfortunately this
has a side effect of disabling all hyphenation in old 7bit fonts as
the fd files for them do not set a \hyphenchar on the assumption the
\defaulthyphenchar would be 45.  So probably all the `OT1' fd files
should be modified to explicitly set \hyphenchar for each OT1 font to
be 45. As the hyphenchar of T1 fonts is not set in the fd files, that
leaves it free for a user to set \defaulthyphenchar to customise
whether 45 or 127 is used.

Unfortunately this needs to be switched before any fonts are loaded
into the format, but a suitable cfg file declaration could be
constructed...

However major open questions relate to multilingual documents. TeX
makes it very inconvenient to have the same font loaded with different
values for the font parameters like hyphenchar, so if you are setting
two different languages, one which `should' use 45 and one which
`should' use 127 then probably there needs to be a compromise
somewhere...

One possible compromise would be to have hyphenation tables that could
`cope' with either setting of hyphenchar. It is almost certainly not
necessary to load extra patterns to prohibit __all__ possible letter
combinations near - as that makes the hyphenation tables very large,
hopefully some smaller set would work `in practice'. Especially if
mono-lingual documents were anyway set with the old 45 position, and so
the extra hyphenation patterns were only needed in special
multi-lingual contexts. (Languages that normally used the 127 slot
might want to load a more extensive range of patterns for - as the
extra memory taken would presumably be justified in those cases)

> Ok, the solution is: type in ^^7f in place of "-" and the problem will
> be solved :-) Or, worst, activate "-"...
The first solution doen't work as  If you type

\documentclass{article}

\usepackage[T1]{fontenc}
\catcode`\^^7f=12

\begin{document}

aaa-bbb

aaa^^7fbbb


\end{document}}

Then you see that ^^7F is totally unsuitable for use as a compound
word character, as it has its side bearings adjusted so that it is a
hanging punctuation. Of course this highlights one of the problems,
the current mess is caused by a typical TeX `compromise' that mixes
two features that ought to be distinct,

* The hyphenation behaviour around an explict hyphen
* The choice of a different glyph for end-of-line hyphens as opposed
  to compound word marks.

While staying with TeX (as opposed to etex or omega or somthing)
these two features may not be separated, anything you do to affect
one, is likely to have an effect on the other. Hopefully LaTeX can
have some kind of interface that hides this as much as possible,
but currently, as I say, it just ducks the issue and does what it
always did and uses slot 45 with no `good' interface for changing
this.

David