Text Formatting ⇒ xspace | Redefine \LaTeX command

[svend_tveskaeg]

Hi all.

Is is possible to (i.e., how do I) redefine the \LaTeX command so that I do not have to write either {\LaTeX} or \LaTeX{} in order to get the correct spacing after the word?

I have tried the following:

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\documentclass{article}

\usepackage{xspace}
\renewcommand*{\LaTeX}{\LaTeX\xspace}

\begin{document}
\LaTeX
\end{document}

I then get the error

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! TeX capacity exceeded, sorry [input stack size=5000].
\LaTeX ->\LaTeX 
                \xspace 
l.7 \LaTeX

Thank you in advance!

[localghost]

You have to "save" the original command into a new one and later use this new command to redefine the old one.

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\documentclass[11pt]{article}
\usepackage[T1]{fontenc}
\usepackage{xspace}

\let\orgLaTeX\LaTeX
\renewcommand*{\LaTeX}{\orgLaTeX\xspace}

\begin{document}
  \LaTeX.

  \LateX rocks!
\end{document}

Otherwise you get an infinite loop, thus the error.


Thorsten

[Stefan Kottwitz]

You can use \expandafter to change the order of the macro expansion, which fixes the problem:

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\expandafter\def\expandafter\LaTeX\expandafter{\LaTeX\xspace}

Another possibility would be using an internal macro to attach \xspace to \LaTeX:

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\makeatletter
\g@addto@macro\LaTeX\xspace
\makeatother

Stefan

[svend_tveskaeg]

Nice.

Thank you, Thorsten and Stefan!

[cgnieder]

The reason why your definition fails is that TeX and thus LaTeX is a macro language. A macro gets replaced by its definition. I would prefer a description for \newcommand/\renewcommand as follows:

• \newcommand\csname{<replacement text>}

So, let's take your definition:

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\renewcommand*{\LaTeX}{\LaTeX\xspace}

and see what happens. I'll use => with the meaning “is replaced by”

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\LaTeX => \LaTeX\xspace => \LaTeX\xspace\xspace => \LaTeX\xspace\xspace\xspace => ...

You can see that this ends up in an endless loop and that's why the capacity exceeded.

The standard way would be something like this:

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% save previous definition:
\let\originalLaTeX\LaTeX
% redefine:
\renewcommand\LaTeX{\originalLaTeX\xspace}

See also the TeX FAQ entry on Patching existing commands.

Regards

PS: bah, too late again

[svend_tveskaeg]

Thank you, Clemens.

Nice explanation.

P.S. Better late than never.