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%$**Header: /swanhills/prof/hoover/lib/tex/macros/RCS/utility.tex,v 1.1 89/09/01 12:58:45 hoover Exp $
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%$**Log:	utility.tex,v $
% Revision 1.1  89/09/01  12:58:45  hoover
% Initial revision
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%
%  Special utility macros used by any civilized tex macro package.
%
%  Note for editing: to put a cr into a line using vi do ^V<cr>
%  Note: put space after constant in \ifnum=0 \stuff
%
%  Definitions of special utility macros used to define macros, check if
%  csnames are already defined, and write messages to the terminal
%
%  def with checking, use the same as a \def eg.
%    \define\mess{\message{hello there}}
%  note: dont try and define \relax, it wont catch the error
%  note: also hope that no one has defined \eat or \dresult
\def\eat#1{}
\def\define#1{\expandafter\ifx\csname\expandafter\eat\string#1\endcsname\relax
   \def\dresult{\def#1}
\else\errmessage{ERROR - define - \string#1\space is already defined}
   \def\dresult{\def\garbage}
\fi\dresult}
%
% check if defined, eg. \checkdef\mess
\def\checkdef#1{\expandafter\ifx\csname\expandafter\eat\string#1\endcsname\relax
\else \errmessage{ERROR - checkdef - \string#1\space is already defined}
\fi }
%
%  make sure that spaces are not eaten following a macro invocation.
\define\dontignorespaces#1{#1}
%
% message function to terminal, but each message on new line
\define\messagel#1{\immediate\write16{#1}}
%
% This write expands its argument list immediately, for example:
%   \expandwrite\refdev{Sequence number \useseq}
% will evaluate the sequence number and place it in the token list to write.
% Otherwise, if the sequence number is changed before the write
% actually occurs the wrong one will be used.
% To delay expansion until the page is actually output, as in the case
% for page numbers, use \noexpand as in:
%   \expandwrite\refdev{Used on page \noexpand\folio}
% To prevent expansion entirely, as when you want to construct macro calls
% for future processing, use \noexpand\noexpand\noexpand as in:
%   \expandwrite\refdev{\noexpand\noexpand\noexpand\rrefer
%   {Theorem \useseq\space on page \noexpand\folio}}
% There must not be a macro called eewrite floating around.
\checkdef\eewrite
\define\expandwrite#1#2{%
\edef\eewrite{\write#1{#2}}%
\ignorespaces\eewrite\ignorespaces}
%
% this saves having to type 3 \noexpand s, as in
%   \expandwrite\refdev
%   {\asis\rrefer{Theorem \useseq\space on page \noexpand\folio}}
\define\asis{\noexpand\noexpand\noexpand}