LaTeX3 from Package Options to Class Options

Question

Howdy please consider the following expample:

\RequirePackage{ expl3 , xparse , l3keys2e , xfrac  }

\ProvidesExplPackage
  {somewhat}
  {2012/04/29}
  {1}
  {descrr}


  \cs_new_nopar:Npn\font_color{green}

  \keys_define:nn {tgquixoptions} {
   font-color .tl_set:N = \tg_font_color, 
   font-color .default:n =\tl_set:Nn\tg_font_color{white},
   background-color .code:n=#1, 
   background-color .default:n = blue,
   }
  \ProcessKeysOptions{tgquixoptions}

  \message{------------message-----\tl_to_str:N\tg_font_color}

This works like a charm. But how can i make this into a Class? I tried this:

\LoadClass{beamer}
\RequirePackage{ expl3 , xparse , l3keys2e , xfrac  }

\ProvidesExplPackage
  {somewhat}
  {2012/04/29}
  {1}
  {descrr}


  \cs_new_nopar:Npn\font_color{green}

  \keys_define:nn {tgquixoptions} {
   font-color .tl_set:N = \tg_font_color, 
   font-color .default:n =\tl_set:Nn\tg_font_color{white},
   background-color .code:n=#1, 
   background-color .default:n = blue,
   }

  \ProcessKeysOptions{tgquixoptions}

  \message{------------message-----\tl_to_str:N\tg_font_color}

It seems that l3 doesn´t process the class options. When called like this:

\documentclass[font-color=somevalue]{somewhat}
%\usepackage[font-color=somevalue]{somewhat}
 \begin{document}
  \frame{
  }
\end{document}

So how can i make l3 listen to Package Options?

Answer 1

Class options are dealt with whenever a class is loaded. Thus if you want to process some package options but also load another class, you need to process your options first

\ProcessLKeysOptions{tgquixoptions}
\LoadClass{beamer}

You may want to use the .unknown property to pass any other options to beamer.

---

Your code in working form:

\begin{filecontents}{somewhat.cls}
\RequirePackage{ expl3 , xparse , l3keys2e , xfrac  }

\ProvidesExplClass
  {somewhat}
  {2012/04/29}
  {1}
  {descrr}


  \cs_new_nopar:Npn\font_color{green}

  \keys_define:nn {tgquixoptions} {
   font-color .tl_set:N = \tg_font_color_tl,
   font-color .default:n =white,
   background-color .code:n=#1, 
   background-color .default:n = blue,
   }

  \ProcessKeysOptions{tgquixoptions}

  \LoadClass{beamer}

  \message{------------message-----\tl_to_str:N\tg_font_color_tl}
\end{filecontents}
\documentclass[font-color=somevalue]{somewhat}
%\usepackage[font-color=somevalue]{somewhat}
 \begin{document}
  \frame{
  }
\end{document}