# File lib/uttk/filters/Filter.rb, line 36
      def self.composition ( *desc )
        class_eval do
          @@desc = desc
          def initialize ( *a, &b )
            super()
            Filters[*@@desc].each do |obs|
              raise ObserverError, obs unless obs.respond_to? :update
              add_observer(obs)
            end
          end
        end
      end

# File lib/uttk/filters/Filter.rb, line 22
      def initialize ( observers=[], options=nil )
        @options = default_options.merge(options || {})
        observers.each do |obs|
          raise ObserverError, obs unless obs.respond_to? :update
          add_observer(obs)
        end
        super()
      end

# File lib/uttk/filters/Filter.rb, line 39
          def initialize ( *a, &b )
            super()
            Filters[*@@desc].each do |obs|
              raise ObserverError, obs unless obs.respond_to? :update
              add_observer(obs)
            end
          end

# File lib/uttk/filters/Filter.rb, line 31
      def notif ( *args )
        changed
        notify_observers(*args)
      end