How do I create a Class using the Singleton Design Pattern in Ruby?

The singleton pattern is a design pattern that is used to restrict instantiation of a class to one object instance. Although I know how to code the singleton pattern in C++ and Java, I was wondering if anyone know how to implement it in Ruby?

From stackoverflow CodingWithoutComments

• Use the singleton module:

  class Clazz
    include Singleton
  end
  

  See http://www.ruby-doc.org/stdlib/libdoc/singleton/rdoc/index.html for more info.

  From cynicalman

• Actually, the above answer was not completely correct.

  require 'singleton'
  
  class Example
    include Singleton
  end
  

  You also need to include the require 'singleton' statement.

  From CodingWithoutComments

• You could use modules to the same effect I believe, although its not "the singleton pattern" you can have global state that way (which is what a singleton is ! Naughty global state !).

  From Michael Neale