module ActionView::Helpers::PrototypeHelper
  
  def build_observer(klass, name, options={})
    if options[:with] && !options[:with].include?("=")
      options[:with] = "'#{options[:with]}=' + value"
    else
      options[:with] ||= 'value' if options[:update]
    end
    
    element_ref = options[:inline] ? "'#{name}'" : 'this'

    callback = options[:function] || remote_function(options)
    javascript  = "new #{klass}(#{element_ref}, "
    javascript << "#{options[:frequency]}, " if options[:frequency]
    javascript << "function(element, value) {"
    javascript << "#{callback}}"
    javascript << ", '#{options[:on]}'" if options[:on]
    javascript << ")"
    
    if options[:inline] 
      javascript_tag(javascript)
    else
      @controller.apply_behaviour("##{name}", javascript)
      return ''
    end
  end
  
end