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Re: [Groff] Conditional problem: "!" operator after "&"
From: |
Tadziu Hoffmann |
Subject: |
Re: [Groff] Conditional problem: "!" operator after "&" |
Date: |
Wed, 28 Jul 2010 20:09:00 +0200 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
> Meanwhile, is this something that would break AT&T troff if
> groff were to do it right?
The question is, what is "right"? I believe you're looking for
a mapping of integers to booleans, and a "not" operator for
booleans. [ntg]roff already has both (in a way):
* positive numbers are "true", nonpositive numbers are "false"
(in contrast to several other languages which use "zero" and
"nonzero").
* if "n" is a number (integer) interpreted as a boolean, then
"not n" is given by "(1-n)".
Thus:
.nr NC 0
.nr SI 0
.if \n(NC&(1-\n(SI) NC only.
.if (1-\n(NC)&\n(SI SI only.
.if \n(NC&\n(SI NC and SI.
.if (1-\n(NC)&(1-\n(SI) neither.
(tested with OSF1 nroff, which only has 1- and 2-character names).