--- ERB::DefMethod.def_erb_method(methodname, erb)
    selferbΥץȤ᥽åɤƤ롣᥽å̾methodnameǻꤹ롣
    selfʸλΥեɤ߹ERBѴΤ᥽åɤȤ롣

      class Writer
        extend ERB::DefMethod
        def_erb_method('to_html', 'writer.erb')
        ...
      end
      ...
      puts writer.to_html

