Documenting options of package

Question

Suppose i have a package like this:

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{test}[2014/08/21 Example package]

\newcommand{\bla}{}
\DeclareOption{optiona}{
    \renewcommand{\bla}{Choice A}
}

\DeclareOption{optionb}{
    \renewcommand{\bla}{Choice B}
}
\ProcessOptions\relax

And i want to write a documentation, where i want to show both options like this:

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[optionb]{test}
\begin{document}
This is the output with optiona:
\bla %prints Choice A
This is the output with optionb:
\bla%prints Choice B
\end{document}

How do i achieve that? i found something about keyval, but honestly, i don't get how that works. Any helpful tips?

Answer 1

The short answer is that you can't retrospectively change options for already loaded packages (see here: Applying options to already loaded package), but if you design your class file carefully then you can probably make hooks for you to latch on to in each case. Using your example:

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{test}[2014/08/21 Example package]

\newcommand{\bla}{}
\newcommand{\abla}{Choice A}
\newcommand{\bbla}{Choice B}
\DeclareOption{optiona}{
    \renewcommand{\bla}{\abla}
}

\DeclareOption{optionb}{
    \renewcommand{\bla}{\bbla}
}
\ProcessOptions\relax

and then in your documentation, something like

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[optionb]{test}
\begin{document}
This is the output with optiona:
\abla %prints Choice A
This is the output with optionb:
\bbla%prints Choice B
\end{document}

The above is ok, but you can be more clever if you use \if commands, something like \if@optiona which is set to true if optiona is specified, and then you can build that into the definition of \bla. Ultimately, however, it always comes down to the same thing: making a way of specifying the two different definitions from the tex file.