User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; sv-SE; rv:1.9.2.22)
            Gecko/20110902 Thunderbird/3.1.14
MIME-Version: 1.0
References: <4E79D279.2050901@morningstar2.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit
Message-ID:  <4E79E2B7.6080906@residenset.net>
Date:         Wed, 21 Sep 2011 15:12:23 +0200
Reply-To: Mailing list for the LaTeX3 project
              <LATEX-L@listserv.uni-heidelberg.de>
Sender: Mailing list for the LaTeX3 project <LATEX-L@listserv.uni-heidelberg.de>
From: =?ISO-8859-1?Q?Lars_Hellstr=F6m?= <Lars.Hellstrom@RESIDENSET.NET>
Subject: Re: \interlinepenalties
To: LATEX-L@listserv.uni-heidelberg.de
In-Reply-To:  <4E79D279.2050901@morningstar2.co.uk>
Precedence: list
Status: R

Joseph Wright skrev 2011-09-21 14.03:
> Hello all,
>
> I am currently working on some galley-related code, and looking at the
> e-TeX extensions to Knuth's paragraph-breaking penalty system. The roles
> of \clubpenalties, \widowpenalties and \displaywidowpenalties are clear,
> and it seems reasonable to provide a documented interface to these
> primitives. On the other hand, \interlinepenalties

(None of these are e-TeX extensions, AFAICT.)

> seems to be very
> difficult both to explain and to see a real case for use. Does anyone
> have experience in using \interlinepenalties, and if so can then suggest
> a good example where it works to solve a real-life problem.

I don't have experience of using it (at least as far as I recall), but 
rereading now the TeXbook description of it, I realise there are a couple of 
cases where I could well have had reason to use it. Imagine a situation 
where you have a long list (typically not in the \begin{list}...\end{list} 
sense) of items -- e.g. lines of source code -- which usually fit on one 
line but sometimes need to be broken into several, and therefore constitute 
paragraphs; it is then natural to discourage page breaks inside an item. Of 
course, for items less than four lines long the \clubpenalty and 
\widowpenalty will usually have significant effect along these lines anyway, 
but I can see \interlinepenalty being closer to what my actual intent would be.

Lars Hellström