NeedsTeXFormat{LaTeX2e}
ProvidesClass{myclass}
RequirePackage{kvoptions}

DeclareBoolOption{foo}

ProcessKeyvalOptions*

ifmyclass@foo
def@title{foo}
else
def@title{bar}
fi

ProcessOptionsrelax

LoadClass{article}

documentclass[foo]{myclass}

begin{document}

maketitle
end{document}

LaTeX Warning: Unused global option(s):
    [foo].