# File lib/listen/listener.rb, line 207
    def on_change(directories, options = {})
      changes = @directory_record.fetch_changes(directories, options.merge(
        :relative_paths => @use_relative_paths
      ))
      unless changes.values.all? { |paths| paths.empty? }
        @block.call(changes[:modified],changes[:added],changes[:removed])
      end
    end