animals.rb

class Animal
  
  attr_reader :name, :age

  def name=(value)
    if value == ""
      raise "Name can't be blank!"
    end
    @name = value
  end

  def age=(value)
  	if value < 0
  	  raise "An age of #{value} isn't valid!"
  	end
  	@age = value
  end

  def talk
    puts "#{@name} says Bark!"
  end

  def move(destination)
    puts "#{@name} runs to the #{destination}"
  end

  def report_age
    puts "#{@name} is #{@age} years old."
  end

end

class Bird < Animal

  def talk
    puts "#{@name} says Chirp! Chirp!"
  end

  def move(destination)
    puts "#{@name} flys to the #{destination}"
  end

end

class Dog < Animal

	def to_s
	  "#{@name} the dog, age #{age}"
	end

end

class Cat < Animal

  def talk
    puts "#{@name} says Meow!"
  end

end

class Armadillo < Animal

  def move(destination)
  	puts "#{@name} unrolls!"
  	super
  end
end

lucy = Dog.new
lucy.name = "Lucy"
lucy.age = 4

rex = Dog.new
rex.name = "Rex"
rex.age = 2

puts lucy.to_s, rex.to_s