act_as.rb

module ActsAsWalker
  attr_reader :distance

  def walk!
    @distance += 1
  end
end

module ActsAsSpeaker
  attr_reader :speak, :gills
end

class Animal
  attr_reader :name, :age

  def initialize name:
    @name = name

    @age = 0
  end


  def birthday!
    @age += 1
  end

  def can_swim?
    @swim
  end

  def can_fly?
    @fly
  end

  def has_milk?
    @milk
  end
end

class Fish < Animal
  include ActsAsSpeaker

  def initialize name:
    super
    @swim = true
    @fly = false
    @milk = false
    @gills = 'yes'
  end

  def speak
    raise NoMethodError
  end
end

class Bird < Animal
  include ActsAsWalker
  include ActsAsSpeaker

  def initialize name:
    super
    @swim = false
    @fly = true
    @milk = false
    @speak = 'car'
    @distance = 0
  end

  def gills
    raise NoMethodError
  end
end

class Mammal < Animal
  include ActsAsWalker
  include ActsAsSpeaker

  def initialize name:
    super
    @swim = false
    @fly = false
    @milk = true
    @speak = 'mo-o-o-o'
    @distance = 0
  end

  def gills
    raise NoMethodError
  end
end

# Fish

fish = Fish.new name: 'Salmon'
p fish.name
p fish.age
fish.birthday!
p fish.age
p fish.can_swim?
p fish.can_fly?
p fish.has_milk?
# p fish.distance #NoMethodError
# p fish.walk! #NoMethodError
# p fish.speak #NoMethodError
p fish.gills

#Bird

bird = Bird.new name: 'Crow'
p bird.name
p bird.age
bird.birthday!
p bird.age
p bird.can_swim?
p bird.can_fly?
p bird.has_milk?
p bird.distance
bird.walk!
p bird.distance
p bird.speak
# p bird.gills #NoMethodError

#Mammal

mammal = Mammal.new name: 'Cow'
p mammal.name
p mammal.age
mammal.birthday!
p mammal.age
p mammal.can_swim?
p mammal.can_fly?
p mammal.has_milk?
p mammal.distance
mammal.walk!
p mammal.distance
p mammal.speak
# p mammal.gills #NoMethodError