From: dblack@...
Date: 2007-06-12T19:46:03+09:00
Subject: Re: self in method name

Hi --

On Tue, 12 Jun 2007, iskaldur wrote:

> Is there any difference between using self in a method name, and not
> using it?
> For example, I've seen a lot something like
>
> class Foo
>    def self.bar
>        ...
>    end
> end
>
> Is this the same thing as
>
> class Foo
>    def bar
>        ...
>    end
> end

def self.bar is just a special case of:

   def some_object.some_method

i.e., defining a singleton method on an object (a method that exists
only in the method look-up for that particular object, not for other
objects of its class).  Actually it's not even a special case; it's
just using the current value of self as the object on which to define
the method.

At the top level of a class definition block, self is the class object
-- in this case, Foo.  A singleton method defined on a class object
(such as Foo.bar) is usually referred to as a class method.  In
addition, class methods are special-cased a bit, in comparison with
other singleton methods... but that's Lesson Two :-)


David

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