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Re: \s[-\n(.s] and \s-\n(.s inconsistent
From: |
Gunnar Ritter |
Subject: |
Re: \s[-\n(.s] and \s-\n(.s inconsistent |
Date: |
Sun, 10 Sep 2006 01:39:25 +0200 |
User-agent: |
Heirloom mailx 12.2pre 7/7/06 |
Werner LEMBERG <address@hidden> wrote:
> > > At the same time, I've disallowed `\s-[-...]' and friends.
> >
> > Why? Their previous behavior was just fine mathematically.
>
> First of all, it isn't documented.
Yes it is: "\s+[N] ... N is a numeric expression".
Note that you are now also disallowing code like
.nr a -3
.nr b 5
\s-[\na+\nb]
Then there is
.ps --2
which is compatible to v7 troff.
> Secondly, it creates an ambiguity:
> shall the second minus character start a relative size change (within
> the relative size change), or shall it start a negative number because
> we already are in `relative' mode?
The first alternative makes no sense to me at all.
AT&T troff always only checks the first character of an expression
to determine if it is relative; a sign as the second character is
interpreted as a unary operator.
Gunnar