Quacking in Ruby

Duck.rb

class Duck
  def initialize(how_to_quack)
    @how_to_quack = how_to_quack
  end

  def how_to_quack=(how_to_quack)
    @how_to_quack = how_to_quack
  end

  def quack
    @how_to_quack.call
  end 
end

just_quacking = lambda {puts "Quack!\n"}
squeaking = lambda {puts "Squeak!\n"}
mute_quacking = lambda {puts "<< Silence >>\n"}

duck = Duck.new(just_quacking)
duck.quack
duck.how_to_quack = squeaking
duck.quack
duck.how_to_quack = mute_quacking
duck.quack