From: dblack@...
Date: 2006-10-10T17:46:50+09:00
Subject: Re: "def self.method" vs "class << self; def method"

Hi --

On Tue, 10 Oct 2006, Ken Bloom wrote:

> joevandyk@gmail.com wrote:
>> What's the difference between
>>
>> class Foo
>>  class << self
>>    def foo; end
>>  end
>> end
>>
>> and
>>
>> class Foo
>>  def self.foo; end
>> end
>
> AFAIK nothing. But you can't do the second one with most
> metaprogrammed methods, for example attr_accessor.

That's a different matter, though (if I'm understanding your point
correctly); the difference between:

   class C
     attr_accessor :x
# and
     class << self
       attr_accessor :x

is not a limitation or exception -- it's just that you're calling
attr_accessor on two different objects (C and C's singleton class).
The first attr_accessor doesn't write methods in the singleton class,
so it's not analogous to def self.x.


David

-- 
                   David A. Black | dblack@wobblini.net
Author of "Ruby for Rails"   [1] | Ruby/Rails training & consultancy [3]
DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central, Inc.   [4]
[1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com
[2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org