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From: piet@cs.ruu.nl (Piet van Oostrum)
Newsgroups: comp.text.tex
Subject: Re: hyphenation with hyphens
Keywords: latex tex
Message-ID: <4306@ruuinf.cs.ruu.nl>
Date: 14 Nov 90 11:24:36 GMT
References: <3684@rwthinf.UUCP>
Sender: news@ruuinf.cs.ruu.nl
Reply-To: piet@cs.ruu.nl (Piet van Oostrum)
Organization: Dept of Computer Science, Utrecht University, The Netherlands
Lines: 28
In-reply-to: norbert@rwthinf.UUCP (Norbert Kiesel)

>>>>> In message <3684@rwthinf.UUCP>, norbert@rwthinf.UUCP (Norbert Kiesel)
>>>>> (NK) writes:

NK> I'm trying to hyphenate words with imbedded hyphens ala 'subsystem-module'.

NK> A \showhyphens{subsystem modul subsystem-modul} gives
NK> ``sub-sy-stem mo-dul subsystem-modul'', i.e. no hyphenation in the third word.

See the TeX book pages 95, 286 and 454: TeX inserts a \discretionary{}{}{}
after a character that is the hyphenchar of its font in unrestricted
horizontal mode. However, a word that contains discretionaries is not
further hyphenated. So you must disable the hyphenchar while reading the
word and enable it while TeX hyphenates (i.e. at the end of the paragraph.

Two ways to do this:

\def\H#1{\setbox0=\hbox{#1}\unhbox0}
\showhyphens{subsystem modul \H{subsystem-modul}}

\edef\savehyphenchar{\the\hyphenchar\the\font}
\hyphenchar\the\font=0
\showhyphens{subsystem modul subsystem-modul
\hyphenchar\the\font=\savehyphenchar} 
-- 
Piet* van Oostrum, Dept of Computer Science, Utrecht University,
Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands.
Telephone: +31 30 531806   Uucp:   uunet!mcsun!ruuinf!piet
Telefax:   +31 30 513791   Internet:  piet@cs.ruu.nl   (*`Pete')