# File lib/action_controller/base.rb, line 484
      def filter_parameter_logging(*filter_words, &block)
        parameter_filter = Regexp.new(filter_words.collect{ |s| s.to_s }.join('|'), true) if filter_words.length > 0

        define_method(:filter_parameters) do |unfiltered_parameters|
          filtered_parameters = {}

          unfiltered_parameters.each do |key, value|
            if key =~ parameter_filter
              filtered_parameters[key] = '[FILTERED]'
            elsif value.is_a?(Hash)
              filtered_parameters[key] = filter_parameters(value)
            elsif block_given?
              key = key.dup
              value = value.dup if value
              yield key, value
              filtered_parameters[key] = value
            else
              filtered_parameters[key] = value
            end
          end

          filtered_parameters
        end
        protected :filter_parameters
      end