How to prevent angle brackets beautification in semiverbatim environment?

Question

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[utf8]{inputenc}

\begin{document}
\begin{frame}[fragile]{Angle Brackets}
\newcommand{\bbb}{\protect\textless\protect\textless\protect\textless}
\begin{semiverbatim}
Wrong:
a <<< b

Right:
a \bbb b
\end{semiverbatim}

\end{frame}
\end{document}

angle brackets

Why is this happening at all? In the beamer documentation it only says that \, {, and } are handled specially.

Also, I can't say that I like my solution very much. I'd rather be able to use <<< as is. Is my solution the only way to go here?

Why is it happening? This is the work of \usepackage[T1]{fontenc} - remove it. — Werner, Jun 15 '13 at 16:23
Hm, you're right, but isn't it good practice to use T1 so that people can copy-paste properly? — letmaik, Jun 15 '13 at 16:26
If good practice leads to this or other problems, then it might not be good practice. It may be your use-case which is problematic. If you wish to keep that functionality, then some intervention is required... — Werner, Jun 15 '13 at 16:38
In my case I actually need fontenc because I use the luximono font which requires it. — letmaik, Jun 15 '13 at 18:18

Przemysław Scherwentke · Accepted Answer · 2013-06-15T16:19:15.773

5

If the question is "how to prevent", an additional grouping will be enough:

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[utf8]{inputenc}

\begin{document}
\begin{frame}[fragile]{Angle Brackets}
\newcommand{\bbb}{\protect\textless\protect\textless\protect\textless}%} % corrected
\begin{semiverbatim}
Wrong:
a <{<}< b % here - PS

Right:
a \bbb b
\end{semiverbatim}

\end{frame}
\end{document}

enter image description here

edited Jun 15 '13 at 16:19

answered Jun 15 '13 at 16:12

Przemysław Scherwentke

37,268

Hm, this doesn't work in lualatex. For the test I used pdflatex where your solution works. – letmaik Jun 15 '13 at 18:01
@neo Tested in pdfLaTeX and XeLaTeX. Probably a bug in luaLaTeX... – Przemysław Scherwentke Jun 15 '13 at 18:13
1

The reason why this does not work in LuaLaTeX, and another solution that does work, is explained in LuaTeX does not respect brace groups used for disabling ligatures - TeX - LaTeX Stack Exchange – user202729 Nov 23 '23 at 09:24
@user202729 Thank you! It is the next reason to choose other engines when it is possible. – Przemysław Scherwentke Nov 24 '23 at 00:27

score 4 · Answer 2 · answered Jun 15 '13 at 19:28

You can modify the definition of semiverbatim.

\documentclass{beamer}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[utf8]{inputenc}

\makeatletter
\def\semiverbatim{%
  \trivlist\item\relax
  \if@minipage\else
    \vskip\parskip
  \fi
  \leftskip\@totalleftmargin
  \rightskip\z@skip
  \parindent\z@
  \parfillskip\@flushglue
  \parskip\z@skip
  \@@par
  \@tempswafalse
  \def\par{%
    \if@tempswa
      \leavevmode\null\@@par\penalty\interlinepenalty
    \else
      \@tempswatrue
      \ifhmode
        \@@par\penalty\interlinepenalty
      \fi
    \fi}%
   \obeylines
   \def\verbatim@nolig@list{\do\<\do\>}%
   \verbatim@font\@noligs\catcode`\<=\active \catcode`\>=\active
   \let\org@prime'%
   \everymath\expandafter{\the\everymath\catcode`\'=12 \let'\org@prime}%
   \everydisplay\expandafter{\the\everydisplay\catcode`\'=12 \let'\org@prime}%
   \def\dospecials{\do\ \do\$\do\&\do\#\do\^\do\_\do\%\do\~\do\`\do\,\do\'\do\-}%
   \let\do\@makeother\dospecials
   \def\\{\char`\\}%
   \def\{{\char`\{}%
   \def\}{\char`\}}%
   \frenchspacing\@vobeyspaces
   \everypar\expandafter{\the\everypar\unpenalty}%
}
\makeatother

\begin{document}
\begin{frame}[fragile]{Angle Brackets}
\newcommand{\bbb}{\protect\textless\protect\textless\protect\textless}
\begin{semiverbatim}
Wrong:
a <<< b

Right:
a \bbb b
\end{semiverbatim}

\end{frame}
\end{document}

Maybe other characters need to be activated. I only disabled the << and >> ligatures.

Unfortunately a simpler patch is not possible, but this redefinition of semiverbatim is very faithful to the original one.

Nice, maybe this should be included in the beamer package. If you don't mind I'll suggest that in the beamer google group. — letmaik, Jun 16 '13 at 08:32

How to prevent angle brackets beautification in semiverbatim environment?

2 Answers2