From: Wilson Bilkovich <wilsonb@...>
Date: 2006-02-17T00:49:06+09:00
Subject: Re: Newbie: how to dynamically add methods?

On 2/16/06, Jeff Cohen <devlists-ruby-talk@devlists.com> wrote:
> The PickAxe doesn't seem to cover details of how to dynamically create
> class or add methods to existing classes.  For example, sometimes I see
> people doing things like this:
>
>  class << self
>   ...
>
> and I'm wondering exactly what's going on.
>
> Anybody know of a good book or online tutorial for this kind of thing?
>

This may help:
http://www.whytheluckystiff.net/articles/seeingMetaclassesClearly.html

class << self is usually used for things that are a bit beyond a basic
method definition.
For example, if you just want to define a new class method called
blah, you could write:
def self.blah
....
end

However, if you want to do alias_method on a class method, you can't do:
alias_method :self.blah, etc, etc.
You need to put it inside a class << self section.