pet_decorator.rb

# Say you have different types of pet classes. It appears that using method_missing is preferable 
# over using DelegateClass as we can decide our target at runtime. Is there a way to accomplish 
# this type of behaviour using DelegateClass ?

def PetDecorator
  def initialize(target)
    @target = target
  end

  def talk
    "-->" + super
  end

  def self.method_missing(method, *args, &block)
    @target.send(method, args, &block)
  end
end

PetDecorator.new(Cat.new)
PetDecorator.new(Dog.new)