module RFuture

  class Delay
    def initialize(&block)
      @block = block
      @called = false
      for m in methods
        if (['__send__', '__id__', '__delayed_value__', 'method_missing'].index  m).nil?
          eval <<END
          def #{m}(*args)
            __delayed_value__.__send__(:#{m}, *args)
          end
END
        end
      end
    end
  
    def method_missing(method_id, *args)
      __delayed_value__.__send__(method_id, *args)
    end
  
    def __delayed_value__
      if @called == false
        @called = true
        @result = @block.call 
      end
      @result
    end
  end


  class Future
    def initialize(&block)
      @block = block
      @ready = false
    
      @thread = Thread.new do
        @result = @block.call
        @ready = true
      end
    
      for m in methods
        if (['__send__', '__id__', '__future_value__', 'method_missing'].index  m).nil?
          eval <<END
          def #{m}(*args)
            __future_value__.__send__(:#{m}, *args)
          end
END
        end
      end
    end
  
    def method_missing(method_id, *args)
      __future_value__.__send__(method_id, *args)
    end
  
    def __future_value__
      if @ready == false
        @thread.join
      end
      @result
    end
  end


  def RFuture.future
    Future.new { yield }
  end

  def RFuture.delay
    Delay.new { yield }
  end
end