Have a parent class's method access the subclass's constants

Question

For example:

class Animal

 def make_noise
    print NOISE
 end

end

class Dog < Animal
    NOISE = \"bark\"
end

d = Dog.new
d.make_noise # I want this to p         


        

Answer 1

If you want it the Object-Oriented Way (TM), then I guess you want:

class Animal
  # abstract animals cannot make a noise
end

class Dog < Animal
  def make_noise
    print "bark"
  end
end

class Cat < Animal
  def make_noise
    print "meow"
  end
end

d = Dog.new
d.make_noise # prints bark

c = Cat.new
c.make_noise # prints meow

If you want to refactor to prevent duplicating the code for print:

class Animal
  def make_noise
    print noise
  end
end

class Dog < Animal
  def noise
    "bark"
  end
end

class Cat < Animal
  def noise
    if friendly
      "meow"
    else
      "hiss"
    end
  end
end

d = Dog.new
d.make_noise # prints bark

c = Cat.new
c.make_noise # prints meow or hiss