How can one put a “[” after \item?

Question

The following does not compile because of the "[" after the \item. I presume it is because LaTeX expects a "]" as per the \item[option] syntax. However, I just want to insert the "[" character into the text as the first character of the enumerated item.

\documentclass[oneside,12pt]{article}

\begin{document}

\begin{enumerate}

\item before

\item [ random text

\item after

\end{enumerate}

\end{document}

I would like LaTeX to generate a document:

before

[ random text

after

One way I've come up with is to put a \ in front of the "[", however I'd appreciate thoughts on the least invasive way to do this.

Answer 1

Just like whenever you want to put a special character (such as a space, or something else) after a command, you can use the {} to supress the next character.

\item{}[your random text

Answer 2

\item looks ahead for the [ character in its definition using \@ifnextchar [:

\def\item{%
  \@inmatherr\item
  \@ifnextchar [\@item{\@noitemargtrue \@item[\@itemlabel]}}

This is done to enable an optional argument for \item. In that sense, using anything other than [ before using [ would suffice.

If you never use the optional argument for \item, you could remove it from its definition and use something different like \Item. That way you can use [ without worrying about it:

\documentclass{article}
\makeatletter
% Remove optional argument from \item
\newcommand{\Item}{\@inmatherr\item\@noitemargtrue\@item[\@itemlabel]}
\makeatother
\begin{document}
\begin{enumerate}
  \Item before
  \Item [ random text
  \Item after
\end{enumerate}
\end{document}

The \item renewal removes the conditional "peeking" for a [ in the input stream, setting the default optional argument to be the regular label. As mentioned, if you never use it in any of your lists, this should be no problem.