Ruby Enumerable和Yield的用法

Question

如果我没有以正确的方式提问，请提前道歉。

试着让这段Ruby代码工作。我不明白的是如何使点击在底部调用yield函数(这是一个交通灯)，以便点击将循环通过yield选项。true, false, false表示灯是红色的，因为它在顶部是亮的，底部的两个灯是假的。我也很难理解enumerator和yield。

class TrafficLight  
  include Enumerable
  include TL
  def each
    yield [true, false, false]
    yield [true, true, false]
    yield [false, false, true] 
    yield [false, true, false] 
  end
end
class Bulb < Shoes::Shape
  attr_accessor :stack
  attr_accessor :left
  attr_accessor :top
  attr_accessor :switched_on
  def initialize(stack, left, top, switched_on = false)    
    self.stack = stack #don't change. 
    self.left = left    
    self.top = top
    self.switched_on = switched_on
    draw left, top, bulb_colour
  end
  # HINT: Shouldn't need to change this method
  def draw(left, top, colour
    )    
    stack.app do
      fill colour
      stack.append do
        oval left, top, 50
      end
    end
  end
  def bulb_colour 
    "#999999"
  end  
end
class GoBulb < Bulb
  def bulb_colour
    "#00FF30"
  end
end
class WaitBulb < Bulb
  def bulb_colour
    "#FFFC00"
  end
end
class StopBulb < Bulb
  def bulb_colour
    "#FF0000"
  end
end
module TL 
  Go = "#00FF30"
  Wait = "#FFFC00"
  Stop = "#FF0000"
end
Shoes.app :title => "My Amazing Traffic Light", :width => 150, :height => 250 do
  background "000", :curve => 10, :margin => 25  
  stroke black    
  @traffic_light = TrafficLight.new
  @top = StopBulb.new self, 50, 40, true     
  @middle = Bulb.new self, 50, 100, true
  @bottom = Bulb.new self, 50, 160, true

  click do #make this switch on/off depending on what you click. Only 1 should be on 
  end
end

我已经谷歌和搜索，但我得到的枚举例子不允许我做我需要做的事情。任何见解都是非常感谢的。

Answer 1

当前版本的Ruby(1.9.1)在Enumerator#next上有一些意想不到的行为。当调用这个方法时，它会卡住。因此，您不能迭代地从Enumerator中检索值。

必须重写TrafficLight类以模拟Enumerator#next。如果next没有这样的错误，我们可以使用TraficLight.new.cycle，并在这个循环枚举器上重复调用' next '。

module TL 
  Go = "#00FF30"
  Wait = "#FFFC00"
  Stop = "#FF0000"
end
class TrafficLight
  include TL
  STATUS = [
    [true, false, false], 
    [true, true, false], 
    [false, false, true],
    [false, true, false]
  ]
  def initialize; @index = 0; end
  def current
    STATUS[@index % STATUS.size]
  end
  def next
    @index += 1
    current
  end
end

更新Bulb，增加一个方法update(on)来重画灯泡

def update(on = false)
  self.switched_on = on
  draw self.left, self.top, on ? self.bulb_colour : '#999999'
end

并更新Shoes.app的主逻辑以使用特定的灯泡:

@traffic_light = TrafficLight.new
@top = StopBulb.new self, 50, 40, true     
@middle = WaitBulb.new self, 50, 100, false
@bottom = GoBulb.new self, 50, 160, false
click do #make this switch on/off depending on what you click. Only 1 should be on 
  status = @traffic_light.next
  [@top, @middle, @bottom].zip(status).each do |light, on|
    light.update(on)
  end
end