I recently needed to create a new macro for a User manual. The macro was to output a defined character, but in a colour specified by the author. Therefore, I needed a macro that accepted a single optional argument.
After doing a lot of searching around, I could only find advice on two or more arguments. I needed this:
Print my symbol in black \specialsymbol please. Print my symbol in red \specialsymbol[red] please. Print my symbol in blue \specialsymbol[blue] please.
The macro is:
\newcommand{\specialsymbol}[1][black]{% \begin{myfont}% \textcolor{#1}{`}% backtick character contains the symbol in the "myfont" font. \end{myfont}% }%
And for extra niceness, if you want your macro to ensure text following the symbol does not butt up hard against it, change line three to:
\textcolor{#1}{`}\ %