How am I supposed to interpret this .cls code?

Question

I am submitting a paper to a journal. In the .cls file the editors provide, the following code appears:

\gdef\@author{\mbox{}}
\def\author{\@ifnextchar [{\@authortwo}{\@authorone}}
\def\@authortwo[#1]#2{\gdef\@author{\uppercase{#2}}\gdef\@shortauthor{#1}}
\def\@authorone#1{\gdef\@author{#1}
\begingroup\gdef\@shortauthor{#1}\endgroup}
\def\shortauthor#1{\gdef\@shortauthor{#1}}
\gdef\@shortauthor{}

I am pretty sure it gives information on how to insert the authors of the paper. Let's say they are called John Haide Well and Maxwell John Baide. How should I write this in my .tex file?

Answer 1

Line by line commentary

\gdef\@author{\mbox{}}

Initialize \@author to an empty box

\def\author{\@ifnextchar [{\@authortwo}{\@authorone}}

Define \author (the user level command) to execute \@authortwo if followed by [, \@authorone otherwise.

\def\@authortwo[#1]#2{\gdef\@author{\uppercase{#2}}\gdef\@shortauthor{#1}}

Define \@authortwo to absorb input of the form \author[x]{y} (we know [ is there; store the bracket-delimited argument into \@shortauthor and the normal argument in \@author but surrounded by \uppercase (programming error here).

\def\@authorone#1{\gdef\@author{#1}
\begingroup\gdef\@shortauthor{#1}\endgroup}

Define \@authorone to store its argument in \@author and also store it in \@shortauthor. Why is the latter command done inside a group is something only the code author can explain. Also, why in only one case the author name is uppercased is a big mystery.

\def\shortauthor#1{\gdef\@shortauthor{#1}}
\gdef\@shortauthor{}

A user level command for storing the short author name in \@shortauthor; the variable is initialized to empty.

Example 1

\author{Abigail Uthor}

We end up with \@author and \@shortauthor both containing Abigail Uthor

Example 2

\author[A. Uthor]{Abigail Uthor}

We end up with \@author containing \uppercase{Abigail Uthor} and \@shortauthor containing A. Uthor

Example 3

\author{Abigail Uthor}
\shortauthor{A. Uthor}

Like in example 2, but without the \uppercase.

Example 4

\shortauthor{A. Uthor}
\author{Abigail Uthor}

Like in example 1, because the redefinition of \@shortauthor by \shortauthor is overridden by the code in \author

Why is \uppercase a programming error?

Obviously, the different behavior when the optional argument is used is an error. However uppercasing should be done when \@author is used, not when it is stored. And \MakeUppercase should be used, anyway.