SRP and OCP example

trafficlight_ocp.rb

class TrafficLightDisplay
  def showState(state)
    puts state == :LIGHT_STATE_RED   ? "*  RED  *" : "   red"
    puts state == :LIGHT_STATE_AMBER ? "* AMBER *" : "  amber"
    puts state == :LIGHT_STATE_GREEN ? "* GREEN *" : "  green"
    puts "---------"
  end
end

class TrafficLight
  def initialize(schedule)
    @state = :LIGHT_STATE_RED
    @schedule = schedule
    @maxTime = schedule.keys.max
    @displays = []
  end

  def cycle
    0.upto @maxTime do |time|
      if @schedule.has_key?(time)
        @state = @schedule[time]
        signalStateChange
      end
      sleep 1
    end
  end
  
  def addDisplay(display)
    @displays.push display
    display.showState @state
  end
  
  def signalStateChange
    @displays.each do |display|
      display.showState @state
    end
  end

  def run
    while true
      cycle
    end
  end
end

tl = TrafficLight.new({
  5=>:LIGHT_STATE_GREEN,
  10=>:LIGHT_STATE_AMBER,
  12=>:LIGHT_STATE_RED
})
tl.addDisplay(TrafficLightDisplay.new)
tl.run

trafficlight_ocp2.rb

class TrafficLightDisplay
  def showState(state)
    puts state == :LIGHT_STATE_RED   ? "*  RED  *" : "   red"
    puts state == :LIGHT_STATE_AMBER ? "* AMBER *" : "  amber"
    puts state == :LIGHT_STATE_GREEN ? "* GREEN *" : "  green"
    puts "---------"
  end
end

class WalkSignalDisplay
  def showState(state)
    puts state == :LIGHT_STATE_RED   ? "*    DON'T WALK       *" : "     don't walk"
    puts state == :LIGHT_STATE_AMBER ? "* BLINKING DON'T WALK *" : "  blinking don't walk"
    puts state == :LIGHT_STATE_GREEN ? "*       WALK          *" : "        walk"
    puts "-----------------------"
  end
end

class TrafficLight
  def initialize(schedule)
    @state = :LIGHT_STATE_RED
    @schedule = schedule
    @maxTime = schedule.keys.max
    @displays = []
  end

  def cycle
    0.upto @maxTime do |time|
      if @schedule.has_key?(time)
        @state = @schedule[time]
        signalStateChange
      end
      sleep 1
    end
  end
  
  def addDisplay(display)
    @displays.push display
    display.showState @state
  end
  
  def signalStateChange
    @displays.each do |display|
      display.showState @state
    end
  end

  def run
    while true
      cycle
    end
  end
end

tl = TrafficLight.new({
  5=>:LIGHT_STATE_GREEN,
  10=>:LIGHT_STATE_AMBER,
  12=>:LIGHT_STATE_RED
})
tl.addDisplay(TrafficLightDisplay.new)
tl.addDisplay(WalkSignalDisplay.new)
tl.run

trafficlight_original.rb

class TrafficLight
  def initialize(schedule)
    setState :LIGHT_STATE_RED
    @schedule = schedule
    @maxTime = schedule.keys.max
  end

  def cycle
    0.upto @maxTime do |time|
      if @schedule.has_key?(time)
        setState(@schedule[time])
      end
      sleep 1
    end
  end

  def setState(newState)
    @state = newState
    showState()
  end

  def showState
    puts @state == :LIGHT_STATE_RED   ? "*  RED  *" : "   red"
    puts @state == :LIGHT_STATE_AMBER ? "* AMBER *" : "  amber"
    puts @state == :LIGHT_STATE_GREEN ? "* GREEN *" : "  green"
    puts "---------"
  end

  def run
    while true
      cycle
    end
  end
end

TrafficLight.new({
  5=>:LIGHT_STATE_GREEN,
  10=>:LIGHT_STATE_AMBER,
  12=>:LIGHT_STATE_RED
}).run

trafficlight_srp.rb

class TrafficLightDisplay
  def showState(state)
    puts state == :LIGHT_STATE_RED   ? "*  RED  *" : "   red"
    puts state == :LIGHT_STATE_AMBER ? "* AMBER *" : "  amber"
    puts state == :LIGHT_STATE_GREEN ? "* GREEN *" : "  green"
    puts "---------"
  end
end

class TrafficLight
  def initialize(schedule)
    @schedule = schedule
    @maxTime = schedule.keys.max
    @display = TrafficLightDisplay.new
    setState :LIGHT_STATE_RED
  end

  def cycle
    0.upto @maxTime do |time|
      if @schedule.has_key?(time)
        setState(@schedule[time])
      end
      sleep 1
    end
  end

  def setState(newState)
    @state = newState
    @display.showState(@state)
  end

  def run
    while true
      cycle
    end
  end
end

TrafficLight.new({
  5=>:LIGHT_STATE_GREEN,
  10=>:LIGHT_STATE_AMBER,
  12=>:LIGHT_STATE_RED
}).run