Counter Game

counter.rb

module Actions
  class Increment
    def self.call(state)
      { count: state[:count] + 1 }
    end
  end

  class Decrement
    def self.call(state)
      { count: state[:count] - 1 }
    end
  end
end

class Graphics
  def self.drawAction(action)
    puts "Aha! An #{action} just happened."
  end

  def self.drawState(state)
    puts "The count is now #{state[:count]}"
  end
end

ActionTypes = [:increment, :decrement]

ActionMap = {
  increment: Actions::Increment,
  decrement: Actions::Decrement
}

class Game
  def self.apply(action, state)
    handler = ActionMap[action]
    handler.call(state)
  end
end

state = { count: 0 }

Graphics.drawState(state)

(1..10).each do |i|
  randomIndex = rand(2)
  action = ActionTypes[randomIndex]
  state = Game.apply(action, state)

  Graphics.drawAction(action)
  Graphics.drawState(state)
end

screenshot.png