poodr_chap6_composition.rb

class Bicycle
  attr_reader :size, :chain, :tire_size

  def initialize(args = {})
    @size       = args[:size]
    @chain      = args[:chain]
    @tire_size  = args[:tire_size]
  end

  def self.default_chain
    '10-speed'
  end

  def spares
    {tire_size: tire_size,
     chain: chain}
  end
end

class RoadBike
  attr_reader :bike, :tape_color

  def initialize(args={})
    @bike = Bicycle.new(default_args.merge(args))
    @tape_color = args[:tape_color]
  end

  def default_args
    {
      chain: Bicycle.default_chain,
      tire_size: default_tire_size
    }
  end

  def spares
    bike.spares.merge({
      tape_color: tape_color
    })
  end

  def default_tire_size
    '23'
  end
end

class MountainBike
  attr_reader :bike, :front_shock, :rear_shock

  def initialize(args={})
    @bike = Bicycle.new(default_args.merge(args))
    @front_shock = args[:front_shock]
    @rear_shock =  args[:rear_shock]
  end

  def default_args
    {
      chain: Bicycle.default_chain,
      tire_size: default_tire_size
    }
  end

  def spares
    bike.spares.merge({
      rear_shock:  rear_shock
    })
  end

  def default_tire_size
    '2.1'
  end
end

class RecumbentBike
  attr_reader :bike, :flag

  def initialize(args={})
    @bike = Bicycle.new(default_args.merge(args))
    @flag = args[:flag]
  end

  def spares
    bike.spares.merge(flag: flag)
  end

  def default_args
    {
      chain: default_chain,
      tire_size: default_tire_size
    }
  end

  def default_chain
    '9-speed'
  end

  def default_tire_size
    '28'
  end
end

bent = RecumbentBike.new(flag: 'tall and orange')
bent.spares