myforwardable.rb

module MyForwardable
  def def_delegator(obj, method)
    define_method(method) do
      self.public_send(obj).public_send(method)
    end
  end
end

class Dog
  def speak
    puts "Bark! Bark! Bark! I am a good boy!"
  end
end

class SayHello
  extend MyForwardable
  def_delegator :pet, :speak

  attr_reader :pet
  def initialize(pet: Dog.new)
    @pet = pet
  end
end

SayHello.new.speak