Ways to create Singleton Methods in Ruby

ways_to_create_ruby_singleton_methods.rb

# Reference: http://madebydna.com/all/code/2011/06/24/eigenclasses-demystified.html

class Dog
  def self.closest_relative
    "wolf"
  end
end

class Dog
  class << self
    def closest_relative
      "wolf"
    end
  end
end

def Dog.closest_relative
  "wolf"
end

class << Dog
  def closest_relative
    "wolf"
  end
end