class extension

class_extension.rb

# see Metaprogramming Ruby, p. 116

# this will not work
#module MyModule
#  def self.my_method; 'hello'; end
#end

module MyModule
  def my_method; 'hello'; end
end

class MyClass
  class << self
    include MyModule
  end
end

puts MyClass.my_method # 'hello'