Using commands inside environment definitions

Question

I want to do something like

\newenvironment{definition}
{
    \textit{
}
{
    }
}

but of course it doesn't work, the braces get mixed up. (In other words, I want that within my environment, the content is surrounded by a command such as \textit or \textbf for instance.) Any ideas?

EDIT : My environment now looks like this :

\newenvironment{definition}
{
    \textbf{\underline{Definition.}}
    \vspace{12 pt}
    \begin{itshape}
}
{
    \end{itshape}
}

minimal working example (MWE) please. – hpesoj626 Mar 09 '13 at 02:08 — hpesoj626, Mar 09 '13 at 02:08

score 11 · Accepted Answer · edited Apr 13 '17 at 12:35

11

In your given example, you can define

\newenvironment{myenv}{\itshape}{}

Actually, the way environments work, you could just use

\begin{itshape} <content> \end{itshape}

but don’t, it is better to have environments named in a meaningful semantic way, say

\newenvironment{emphasize}{\itshape}{}
\begin{emphasize} <content> \end{emphasize}

If you really need to use a macro that expects a parameter (like \textit) you can use the environ package and its \BODY macro as demonstrated by Werner.

edited Apr 13 '17 at 12:35

Community

1

answered Mar 09 '13 at 02:26

Qrrbrbirlbel

119,821

Thanks! Actually I chose the \begin{itshape}/\end{itshape} first and it work just fine... what exactly is wrong with it? – Patrick Da Silva Mar 09 '13 at 03:08
2

@PatrickDaSilva it is better to have a meaningful name for the environment. It's purpose surely isn't a demonstration of italic font shape, is it? IMHO the name of the environment should reflect its meaning and not what it is actually doing. – cgnieder Mar 09 '13 at 08:25
I edited my question to show what I actually did. Is it what you meant? – Patrick Da Silva Mar 13 '13 at 17:15
@PatrickDaSilva Yes, but remember, there isn’t an itshape environment but an \itshape font switch. A better definition would be \newenvironment{definition}{\textbf{\underline{Definition.}}\vspace{12 pt}\itshape}}{} (no additional group). – Qrrbrbirlbel Mar 13 '13 at 19:01

score 11 · Answer 2 · answered Mar 09 '13 at 02:33

11

In a general setting, you wish to capture the entire environment into a macro, and then pass that macro to another macro as an argument. That is exactly what the environ package provides:

enter image description here

\documentclass{article}
\usepackage{environ}% http://ctan.org/pkg/environ
\NewEnviron{myenv}[1][\textit]{%
  #1{\BODY}%
}
\begin{document}
\begin{myenv}
Hello World!
\end{myenv}

\begin{myenv}[\textbf]
Hello World!
\end{myenv}

\begin{myenv}[\slshape]
Hello World!
\end{myenv}

\begin{myenv}[]
Hello World!
\end{myenv}
\end{document}

environ allows you to capture the contents of the environment into the macro \BODY, which is then usable for whatever means. My definition prints it using \textit by default, but you can modify that using a different macro or font switch.

The above definition of myenv is general enough to allow for formatting of the environment content using a macro or a switch (as is done in the 3rd example). Supplying an empty (optional) argument removes any formatting.

answered Mar 09 '13 at 02:33

Werner

603,163

Interesting package. I don't think I need something so refined to do a simple italic in an environment though, your package seems to be able to do a lot. – Patrick Da Silva Mar 09 '13 at 03:09
What if you want to use \begin{verbatim}? Then \BODY won't work... – Someone Apr 14 '20 at 15:11
@Someone True, but is it necessary in your instance? Do you have bizarre symbols you want within the output? There are some alternatives, but it may depend on your actual use-case. – Werner Apr 14 '20 at 21:45
I wanted to put verbatim text into a colored background. – Someone Apr 22 '20 at 21:14
@Someone: See Getting verbatim with soft grey background, as in tex.stackexchange – Werner Apr 22 '20 at 21:44

score 2 · Answer 3 · answered Mar 09 '13 at 02:09

2

\documentclass{article}
\newenvironment{myenv}{\fontshape{it}\selectfont}{\fontshape{n}\selectfont}
\begin{document}
Before the environment

\begin{myenv}
Testing in the environment
\end{myenv}

Out of the environment
\end{document}

answered Mar 09 '13 at 02:09

Steven B. Segletes

237,551

4

Or you could just use \itshape. ;) As the environment itself acts as a group, you don’t need the end part. – Qrrbrbirlbel Mar 09 '13 at 02:22
Yeah, but I got yelled at in http://tex.stackexchange.com/questions/99292/lowercase-small-caps-in-section-subsection/99295#99295 for getting clever with \sc, so I now try to stick to orthodox solutions... especially with Werner on the thread. – Steven B. Segletes Mar 09 '13 at 02:43
@Steven : I must admit I don't know much about \sc, and something clever is not really relevant to me because I'm asking for something but I want to be able to work with it a little bit, otherwise I don't understand what's going on and I can't adapt your ideas to my work. Codes that "read easily" are more appropriate answers than clever codes that are very intricate... I +1'ed your answer but I prefered Qrrbrbirlbel's. – Patrick Da Silva Mar 09 '13 at 03:11
@PatrickDaSilva : Understood, and thanks. Here's a good reference for using/changing font attributes: http://latex-project.org/guides/fntguide.pdf – Steven B. Segletes Mar 09 '13 at 03:17
2

@StevenB.Segletes While \sc is a deprecated command, \itshape or \scshape aren't. Using lower level commands such as \fontshape and \selectfont is best avoided if higher level declarations are available. – egreg Mar 09 '13 at 10:11
@egreg Thanks. I can't win, it would seem. I must have difficulty keeping it all straight, but I appreciate the reminders. – Steven B. Segletes Mar 09 '13 at 13:32

Using commands inside environment definitions

3 Answers3