LaTeX package "titling", titles with hard line breaks, and \MakeUpperCase

Question

I have a document with a title that is spread over several lines using hard line breaks. To configure the title formatting, I use the titling package with code adapted from its documentation:

\documentclass{article}

\usepackage{titling}
\pretitle{\begin{center}\LARGE\sffamily\bfseries}
\posttitle{\par\end{center}\vskip 0.5em}

\title{Higgelty Pigglety Pop! \\ or \\ There Must Be More to Life}

\begin{document}
\maketitle
\end{document}

…and it works perfectly.

I now want the title additionally to be in all caps and therefore change the \pretitle command:

\pretitle{\begin{center}\LARGE\sffamily\bfseries\MakeUppercase}

…and I get the following error message:

! Use of \@icentercr doesn't match its definition.
<argument> \def

l.12 \maketitle

This only happens with a title that includes hard line breaks.

What does this error message mean? How can I fix it?

Answer 1

Split the title at \\ and apply \MakeUppercase to each chunk:

\documentclass{article}

\usepackage{titling}
\pretitle{\begin{center}\LARGE\sffamily\bfseries}
\posttitle{\par\end{center}\vskip 0.5em}
\makeatletter
\renewcommand{\title}[1]{\gdef\@title{\DoUppercase{#1}}}
\DeclareRobustCommand\DoUppercase[1]{\Do@Uppercase#1\\\@nil}
\def\Do@Uppercase#1\\#2\@nil{%
  \MakeUppercase{#1}%
  \ifx\\#2\\%
    \expandafter\@gobble
  \else
    \\\expandafter\@firstofone
  \fi
  {\Do@Uppercase#2\@nil}%
}
\makeatother

\title{Higgelty Pigglety Pop! \\ or \\ There Must Be More to Life}

\begin{document}
\maketitle
\end{document}

This is obtained by redefining \title to store \DoUppercase{<title>} in \@title rather than just the title.

You can't use the vertical spacing optional argument to \\, though.

If you want to support also \\[3pt] or whatever, then it is possible with l3regex.

\documentclass{article}
\usepackage{xparse,l3regex}
\usepackage{titling}
\pretitle{\begin{center}\LARGE\sffamily\bfseries}
\posttitle{\par\end{center}\vskip 0.5em}
\makeatletter
\renewcommand{\title}[1]{\gdef\@title{\DoUppercase{#1}}}
\makeatother

\ExplSyntaxOn
\NewDocumentCommand{\DoUppercase}{m}
 {
  \tl_set:Nn \l_tmpa_tl { #1 }
  \tl_set:Nn \l_tmpb_tl { \\ }
  % Add \MakeUppercase{ at the beginning and } at end
  \regex_replace_once:nnN
   { (.*) }
   { \c{MakeUppercase}\cB\{\1\cE\}} \l_tmpa_tl
  % change \\[...] into }\\[...]\MakeUppercase{
  \regex_replace_all:nnN
   { \u{l_tmpb_tl}\[(.*?)\] }
   { \cE\}\u{l_tmpb_tl}\[\1\]\c{MakeUppercase}\cB\{ }
   \l_tmpa_tl
  % change \\ into }\\\MakeUppercase{
  \regex_replace_all:nnN
   { \u{l_tmpb_tl}([^\[]) }
   { \cE\}\u{l_tmpb_tl}\c{MakeUppercase}\cB\{\1 }
   \l_tmpa_tl
  \tl_use:N \l_tmpa_tl
 }
\ExplSyntaxOff

\title{Higgelty Pigglety Pop! \\[3pt] or \\ There Must Be More to Life}

\begin{document}
\maketitle
\end{document}

Answer 2

This problem arises because \\ is redefined in the center environment to something fragile, which \MakeUppercase doesn't like (see also this answer). The simplest way to get this title to work is to \protect the \\:

\title{Higgelty Pigglety Pop! \protect\\ or \protect\\ There Must Be More to Life}

Answer 3

Here's a solution with stringstrings. The reason it does not work directly with \MakeUppercase is that the argument of the title contains the macro \\. I am presuming that the \MakeUppercase macro works only or regular expressions without macros. In general the stringstrings package has the same limitations, but it does have provisions for limited exceptions.

What the logic does is tell stringstrings to pre-encode each \\ into a ASCII-encoded sequence. It then can operate \caseupper on this sequence using its [e] encoded mode (which does not print out an immediate result, instead storing it in the expanded macro \thestring). The \retokenize macro is needed to process \thestring, reconverting each ASCII-encoded \\ back into the LaTeX macro \\.

In the course of answering this question, a bug was discovered in the stringstrings package which required the following patch.

\usepackage{xpatch}
% BUG FIX
\makeatletter
\xpatchcmd{\@retokenizechar}{{~}}{{\ }}
\makeatother

However...

UPDATE: The stringstrings package was upgraded to V1.23 on 2 FEB 2015, to resolve this bug. Here is the revised MWE, without the need for a patch.

\documentclass{article}
\usepackage{titling,stringstrings}

\pretitle{\begin{center}\LARGE\sffamily\bfseries%
\encodetoken{\\}\caseupper[e]%
}
\posttitle{\retokenize{\thestring}%
\thestring\par\end{center}\vskip 0.5em}

\title{Higgelty Pigglety Pop!\\or\\There Must Be More to Life}

%Now Works for string without \\
%\title{Higgelty Pigglety Pop! or There Must Be More to Life}

\begin{document}
\maketitle

\clearpage
\end{document}

Answer 4

A simple solution is to load David Carlisle textcase package with the option overload. Then you just put the \\-macro into a \NoCaseChange{}, i.e.

\usepackage[overload]{textcase}

...
...

\title{Higglety, Pigglety Pop!\NoCaseChange{\\}or\NoCaseChange{\\} 
      There must be more to life}