CODEWITHSUNDEEP
rubyshoesenumerator
jenno
jenno

Reputation: 71

Ruby Enumerable and Yield usage

Sorry in advance if I am not asking my question in the correct way.

Trying to get this bit of Ruby code to work. What I don't understand is how to make the click do at the bottom call the yield functions (it's a traffic light) so that a click will cycle through the yield options. The true, false, false will mean the light is red because it's on at the top and the 2 bottom ones are false. I'm also having a hard time wrapping my head around enumerator and 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

I've Googled and searched but the enumerator examples I got didn't allow me to do what I needed to do. Any insight is greatly appreciated.

Upvotes: 1

Views: 194

Answers (1)

Arie Xiao
Arie Xiao

Reputation: 14082

The Ruby (1.9.1) packed with current version of Shoes has some unexpected behavior on Enumerator#next. It gets stuck when this method is called. So you cannot iteratively retrieve values from an Enumerator.

The TrafficLight class has to be rewrited to mimic the Enumerator#next. If there isn't such bug on next, we can use TraficLight.new.cycle and repeatedly call `next on this cycling enumerator.

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

Update Bulb, add a method update(on) to redraw the bulb.

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

And update the main logic of Shoes.app to use specific bulb:

@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

Upvotes: 2

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