# File lib/merb-core/controller/template.rb, line 177
    def register_extensions(engine, extensions) 
      raise ArgumentError, "The class you are registering does not have a compile_template method" unless
        engine.respond_to?(:compile_template)
      extensions.each{|ext| EXTENSIONS[ext] = engine }
      Merb::AbstractController.class_eval "include \#{engine}::Mixin\n"
    end