From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-08-16T03:32:37+09:00
Subject: Re: no clue

On Tue, 16 Aug 2005, Joe Van Dyk wrote:

> Isn't
> def self.create(*a)
> ...
>
> clearer than
>
> class << self
>  def create(*a)

not when you end up using 'attr' type meta-programming, having class methods
which refer to class methods, aliases, and other things that complicate the
matter:


   harp:~ > cat b.rb
     class C
       class << self
         attr 'a'
         attr 'b'
         alias class_a a
         alias class_b b
         def class_initialize
           @a, @b = 4, 2
         end
         def class_method
           puts [class_a, class_b].join('')
         end
       end

       self.class_initialize

       attr 'a'
       attr 'b'
       alias inst_a a
       alias inst_b b
       def initialize
         @a, @b = 'forty', 'two'
       end
       def instance_method
         puts [inst_a, inst_b].join('-')
       end
     end

   c = C::new
   C::class_method
   c.instance_method


   harp:~ > ruby b.rb
   42
   forty-two


note how 'attr', 'alias', calls to methods that do not specify a receiver, and
instance variables are all consistently in the class scope here.  to me this is
clearer than

   class C
     class << self
       attr 'a'
       attr 'b'
     end
     def self::c
       a + b
     end
   end

i always (o.k. mostly) setup my classes like

   class
     # all constants
     class << self
       # all class stuff
     end
     # all instance stuff
   end

if you use the the 'def self::method' approach you cannot be consistent since
some things don't work that way - like 'attr' and 'alias'.  for me it's just
an idiom that makes my code clearer, more consistent, and avoids typing.

> ?  I mean, they both create a class method, right?

yes.

hth.

-a
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