42

With a macro such as:

\def\naive{na\"{\i}ve}

I find that the space which I would hope to follow it, is absent. So, with

the \naive approach

I get

the naïveapproach

in the output. How do I bring back the space?

lockstep
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user4417
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8 Answers8

39

The problem of using \naive\ or \naive{}: If you happen to forget the closing backslash/braces, you'll end with gobbled space without noticing it.

The problem of adding \xspace to a macro's definition: This may produce inconsistent spacing if the macro uses \emph. See xspace and italic correction for details.

In the thread linked above, Will Robertson suggested to use "delimited" macros (e.g. with / at the end) as an alternative. The main advantage of \naive/ is that an error message will occur if you happen to forget the closing slash.

(See also the comments to this answer.)

\documentclass{article}

\newcommand{\naive}{}% To make sure that \naive isn't already defined    
\def\naive/{na\"{\i}ve}

\begin{document}

the \naive/ approach

\end{document}

enter image description here

Community
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lockstep
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  • 1
    the \newcommand should be a \providecommand and then you can use a \renewcommand –  Aug 16 '11 at 10:59
  • 4
    @Herbert: a) I want TeX to throw an error, not to silently overwrite an existing definition, so it's \newcommand for me. b) AFAIK, \renewcommand doesn't work for delimited macros. – lockstep Aug 16 '11 at 11:02
  • 2
    no, then it should be \@ifdefinable{...} –  Aug 16 '11 at 11:13
  • @Herbert: I don't know \@ifdefinable{...}, why is it better? – user4417 Aug 16 '11 at 11:53
  • then you can out a message in the text, which the user understand! –  Aug 16 '11 at 11:57
15

Use the package xspace. It

provides a single command that looks at what comes after it in the command stream, and decides whether to insert a space to replace one "eaten" by the TeX command decoder.

For your case it can be used as in the following:

\documentclass{article}

\usepackage{xspace}

\def\naive{na\"{\i}ve\xspace}

\begin{document}

the \naive approach

\end{document}
lockstep
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N.N.
  • 36,163
6

Use braces \naive{} or \naive\ or xspace. See the FAQ: https://texfaq.org/FAQ-xspace

David Carlisle
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Ulrike Fischer
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4

The problem is that the follwing space is uses as macro end. Type \navie{} or use the xspace package.

\documentclass{minimal}

\usepackage{xspace}
\newcomand{\naiv}{naiv\xspace}

\begin{document}
Test \naiv Test.
\end{document}
Tobi
  • 56,353
3

A dirty trick: Use a special character in the macro name (not working with \newcommand): 

\documentclass{article}
\def\¶naive{na\"{\i}ve}
\begin{document}
the \¶naive approach
\end{document}

MWE

Note: Do no start another macro with the same special character, although is possible use again this character in another position.

Fran
  • 80,769
3

I don't know xspace package but I mean that it does somethig similar to this:

\def\maybespacelist{.,;!?}
\def\maybespace{\let\nexxt=\space 
   \edef\maybespaceA{\noexpand\maybespaceB\maybespacelist\relax}%
   \futurelet\next\maybespaceA
}
\def\maybespaceB#1{\ifx#1\relax \nexxt \else \ifx#1\next \let\nexxt=\relax\fi
   \expandafter\maybespaceB\fi
}
\protected\def\naive{na\"{\i}ve\maybespace}

The \naive approach. The approach is \naive.

\bye
wipet
  • 74,238
3

Quick answer: the \naive\ approach

Better answer: Use the xspace-package

\usepackage{xspace}
\newcommand{\better\xspace }
...

the \better approach

Advantage: xspace take a look on the next character. So you have not an obsolete space in:

Macro at sentence end\better.
Seamus
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knut
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3

For completeness, you could also define the macro as

\def\naive#{na\"{\i}ve}

which will require that it be followed by {} when ever it is used. For example, the \naive{} approach will work whereas the \naive approach will raise an error which says Use of \naive doesn't match its definition..

See page 204 of The TEXbook for details. Also, this answer may be of interest.

Community
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Guho
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