From: surge <gerases@...>
Date: 2007-06-21T06:40:27+09:00
Subject: class << self idiom

Hello,

I have trouble understanding the need for the class << self idiom. For
example, let's say I have this class:

class My_Class
 def method_1
 end
end

Now, I want to extend that class. I can do:

class My_Class
 def method_2
 end
end

or:

class My_Class
 class << self
   def method_2
   end
 end
end

I understand that in the second case we're extending the singleton
class of My_Class, but why is the second form so often used in Ruby
vs. the other form? Isn't the end result identical?