def convert_codeblock(el, opts)
show_whitespace = el.attr['class'].to_s =~ /\bshow-whitespaces\b/
lang = el.attr['lang']
if show_whitespace || lang
options = []
options << "showspaces=%s,showtabs=%s" % (show_whitespace ? ['true', 'true'] : ['false', 'false'])
options << "language=#{lang}" if lang
options << "basicstyle=\\ttfamily\\footnotesize,columns=fixed,frame=tlbr"
id = el.attr['id']
options << "label=#{id}" if id
attrs = attribute_list(el)
"#{latex_link_target(el)}\\begin{lstlisting}[#{options.join(',')}]\n#{el.value}\n\\end{lstlisting}#{attrs}\n"
else
"#{latex_link_target(el)}\\begin{verbatim}#{el.value}\\end{verbatim}\n"
end
end