Path: utzoo!attcan!uunet!van-bc!ubc-cs!fornax!laughlin
From: laughlin@fornax.UUCP (Bob Laughlin)
Newsgroups: comp.text.tex
Subject: variables in \def
Keywords: tex macros
Message-ID: <2206@fornax.UUCP>
Date: 28 Feb 91 02:16:46 GMT
Organization: School of Computing Science, Simon Fraser University
Lines: 22


    After years of using LaTeX pretty much as is, I'm starting to
write my own TeX macros. I'd like to know the best way to
allocate and use dimen and count registers in a macro. 

    I know I can reserve these with \newdimen\mydimen etc. or use
certain ones as scratch registers, e.g. \dimen0 - \dimen9.
The problem is \newdimen is outer and can't be used in
a \def and so if I'm not mistaken \mydimen has to be global to the whole
macro set. In a large macro package you could have an unwieldy
set of global dimen names. 

    In addition, since \dimen0 etc. are scratch registers if you call
other macros in your macro there is no guarantee that they will not
also use these registers and presumably destroy the contents.
At least thats what I think the TeXbook says.

    Is there a mechanism for generating the equivalent of automatic
local variable in C for TeX macros? Something whose name is hidden
in the macro and disappears after the macro is executed?
-- 
 Bob Laughlin  laughlin@cs.sfu.ca