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From: jeburke@jhunix.HCF.JHU.EDU (John Burke)
Newsgroups: comp.text.tex
Subject: Re: Strange result in macros
Summary: Not so strange after all
Keywords: simple parameters
Message-ID: <7403@jhunix.HCF.JHU.EDU>
Date: 24 Jan 91 14:43:49 GMT
Expires: 31 Jan 91 00:00:00 GMT
References: <1991Jan24.095405.8868@uni-paderborn.de>
Followup-To: comp.text.tex
Organization: The Johns Hopkins University - HCF
Lines: 43

In article <1991Jan24.095405.8868@uni-paderborn.de> elmar@pbinfo.UUCP (Elmar Schalueck) writes:
>%  I discovered a beautiful difference in macros depending
>%  on the position of the left braces after the macroname.
>%  Is this a desired effect and how can I make use of it to apply
>%  macros to whole words that are not surrounded by braces?
>%
>%  Greetings and have some fun with the example below
>%
>%  Elmar Schal\"{u}ck           elmar@uni-paderborn.de
>%
>%
>\documentstyle{article}
>\begin{document}
>\long\def\foo#1
>{Hurrah #1 Hurrah}
>\long\def\gnat#1{Yippee #1 Yippee}
>Now I test \foo{Why} and \gnat{Why not?} and everything's ok.
>
>But watch out for the difference to \foo{Me}-too and \gnat{You}-never.
>\end{document}

From _The TeXbook_, p. 201 (of my copy, anyway, pre-3.0):
<dangerous bend>  Caution: When you define a macro with simple
parameters, as in these examples, you must be careful not to put blank
spaces before the '{' that begins the replacement text. For example,
'\def\row #1 #2 {...}' will not give the same result as
'\def\row#1#2{...}', becuase the spaces after #1 and #2 tell TeX to
look for arguments that are followed by spaces.  (Arguments can be
"delimited" in a fairly general way, as explained below.)  But the
space after \row is optional, as usual, becuase TeX always disregards
spaces after control words.  After you have said '\def\row#1#2{...}',
you are allowed to put spaces between the arguments (e.g., '\row x
n'), because TeX doesn't use single spaces as undelimited arguments.
---

... in other words, look for answers to all life's trying questions in
the Good Book.  Blessed be Donald Knuth, and the horse He rode in on.

John Burke
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jeburke@jhunix.hcf.jhu.edu                    | Johns Hopkins doesn't
Homewood Academic Computing Information Center| want my opinions.  Why was
The Johns Hokins University                   | he selling whiskey, though.
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