Detect when a white space is needed after calling a command

Question

Say I have an expression I often use so I build a command shortcut to typeset it:

\documentclass[11pt]{report}
\usepackage{xparse}
\ProvideDocumentCommand \es{s}{expression shortcut\IfBooleanTF{#1}{s}{}}
\begin{document}
This is a \es and These are \es*.
\end{document}

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Can I avoid the manual addition of tilde (~) when the call is made within a sentence? In other words, is there a way to detect (using xparse or not) when Latex shouldn't "eat" the following white space?

tex will always eat the space in deciding which command it is, however as Paul says you can use xspace to put the space back, but before doing that read drawbacks of xspace — David Carlisle, Mar 25 '15 at 13:34
Well, since this is exactly what I need and since there appears to be no better way to do it, I'll use xspace. Thanks. — nadous, Mar 29 '15 at 10:43

oxio · Accepted Answer · 2015-03-25T15:08:25.783

2

In fact, according to The Not so short introduction to Latex (section 1.3.3), Latex ignores whitespaces after commands, so, quoting:

If you want to get a space after a command, you have to put either an empty parameter {} and a blank or a special spacing command after the command name

So either you use empty arguments or something like \hspace{0.5em} (or whatever space suits you better).

Edit:

Following Paul's advice, I tried the \xspace command and the trick is to include \usepackage{xspace} and inside the definition, include the command, like

\ProvideDocumentCommand \es{s}{expression shortcut\IfBooleanTF{#1}{s}{}\xspace}

I just tested it :)

edited Mar 25 '15 at 15:08

answered Mar 25 '15 at 13:16

oxio

98

4

Instead of hard-coding the size of the space, it's better to use control space \ so that TeX's glue is not adversely affected. And as mentioned in my comment above, there is also the option of \xspace. BTW, even though you've been around for a while, this is your first answer, so: Welcome to TeX.SX! :-) – Paul Gessler Mar 25 '15 at 13:26
Thanks :) I didn't know the option of \xspace, I think I will have to learn about it – oxio Mar 25 '15 at 15:01

Detect when a white space is needed after calling a command

1 Answers1