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Formatting Information — An introduction to typesetting with LATEX

Chapter 7: Programmability

Section 7.2: Macros using information gathered previously

A more complex example is the macro \maketitle which is used in almost every LATEX document to format the title block. In the default document classes (book, report, and article) it performs small variations on the layout of a centred block with the title followed by the author followed by the date, as we saw in § 2.3.

If you inspect one of the default document class files, such as report.cls you will see \maketitle defined (and several variants called \@maketitle for use in different circumstances). It uses the values for the title, author, and date which are assumed already to have been stored in the internal macros \@title, \@author, and \@date by the author using the matching \title, \author, and \date commands in the document before using the \maketitle command.

This use of one command (eg \title) to store the information in another (eg \@title) is a common way of gathering the information from the user. The use of macros containing the @ character prevents their accidental misuse by the user because they designed for use in packages and classes, and are disallowed in document text. To use them in your Preamble (eg to redefine \maketitle), you have to allow the @ sign to temporarily become a ‘letter’ using the \makeatletter command so the @ can be recognised in a command name (and remember to turn it off again afterwards with the \makeatother command — see the listitem ‘Enclosed the changes in makeatletter and …’ below).

\makeatletter
\renewcommand{\maketitle}{%
   \begin{flushleft}%
      \sffamily
      {\Large\bfseries\color{red}\@title\par}%
      \medskip
      {\large\color{blue}\@author\par}%
      \medskip
      {\itshape\color{green}\@date\par}%
      \bigskip\hrule\vspace*{2pc}%
   \end{flushleft}%
}
\makeatother
      

Insert this immediately before the \begin{document} in the sample file in the first listing, and make sure you have used the xcolor package. Typeset the file and you should get something like Figure 7.1.

Figure 7.1: Example of reprogrammed title layout

newtitle 

In this redefinition of \maketitle, we’ve done the following:

  1. Enclosed the changes in \makeatletter and \makeatother to allow us to use the @ sign in command names;

  2. Used \renewcommand and put \maketitle in the first pair of curly braces after it;

  3. Opened a second pair of curly braces to hold the new definition. The closing curly brace of this pair is immediately before the \makeatother;

  4. Inserted a flushleft environment so the whole title block is left-aligned;

  5. Used \sffamily so the whole title block is in the defined sans-serif typeface;

  6. For each of \@title, \@author, and \@date, we have used some font variation and colour, and enclosed each one in curly braces to restrict the changes just to each command. The closing \par of each one makes sure that multiline title and authors and dates would get typeset with the relevant line-spacing;

  7. Added some flexible space between the lines, and around the \hrule (horizontal rule) at the end;

Note the % signs after any line ending in a curly brace, to make sure no intrusive white-space find its way into the output. These aren’t needed after simple commands where there is no curly brace because excess white-space gets gobbled up there anyway.

Exercise 16: Rewriting the title

Add the code above to your test document (or create a new one), then add title, author, and date, and make your new title.

  1. If you move all this Preamble into a package (.sty) file of your own, you don’t need these commands: the use of @ signs in command names is allowed in package and class files.