From: Matma Rex <matma.rex@...>
Date: 2013-01-10T07:26:24+09:00
Subject: Re: Extending class

On Wed, 09 Jan 2013 23:12:31 +0100, Damjan Rems <lists@ruby-forum.com> wrote:
> Is there a clear way of extending classes?

`extend Something` is mostly the same as `class << self; include Something; end`.

The `class << something` syntax opens the "singleton class" (aka "eigenclass") of `something`; include is just your regular include.

For example:

module MyModule
     def test; puts "Hello world!"; end
end

class MyClass
     class << self
         include MyModule
     end
end

MyClass.test # => Hello world!

The combination means that the methods included from MyModule end up as class methods of MyClass.

-- 
Matma Rex