stuart

composition.rb

class Movement
  
  attr_reader :distance
  
  def initialize(distance)
    @distance = distance
  end
  
  def move
    puts "moved #{@distance} miles"
  end
  
end

class Tesla
  
  def initialize
    @movement = Movement.new(2)
  end
  
  def move
    @movement.move
  end
  
end

class Ford
  
  def initialize
    @movement = Movement.new(3)
  end
  
  def move
    @movement.move
  end
  
end

vehicle.rb

class Vehicle

  attr_reader :driver, :distance
  
  def initialize(driver)
    @driver = driver
    @distance = 0
  end

  def self.move(vehicle)
    vehicle.move
  end
  
end

class Bicycle < Vehicle
  
  def move
    @distance += 2
  end

end

class Motorbike < Vehicle
  
  def move
    @distance += 4
  end

end

class Car < Vehicle
  
  def move
    @distance += 6
  end
  
end