emitter.rb

  class Emitter

    def initialize(&block)
      @block = block
    end

    def run(nodes, &block)
      nodes.each do |id, node|
        block.call(Fiber.new { 
          @block.call(id, node, self)
        }.resume)
      end
    end

    def emit(*args)
      Fiber.yield(*args)
    end

  end

# ruby-1.9.2-p180 :145 > e = Emitter.new { |a,b,c| c.emit(a+b) }
#   => #<Emitter:0x000001009485d0 @block=#<Proc:0x00000100948580@(irb):145>> 
# ruby-1.9.2-p180 :146 > e.run({1=>2,3=>4}) do |t|
# ruby-1.9.2-p180 :147 >     puts "Total: #{t}"
# ruby-1.9.2-p180 :148?>   end
# Total: 3
# Total: 7