From: Robert Dober <robert.dober@...>
Date: 2007-05-02T07:11:19+09:00
Subject: Re: simple subclass question

On 5/1/07, Ball, Donald A Jr (Library) <donald.ball@nashville.gov> wrote:
> Thanks to you and Robert for the quick answers. I think I get it now; I
> was a little fuzzy on the notion of class instance variables before. I
> now use a construct like so:
>
> class A
>   class << self
>     attr_accessor :var
>   end
> end
>
> class B < A
>   class << self
>     def var
>       @var || superclass.var
>     end
>   end
> end
>
> to allow subclasses's instance variables to default to their
> superclass's until and unless overridden.

That was the point I missed, but of course you did that nicely :).
I'll admit the class << self
> syntax continues to mystify somewhat; can anyone proffer an explanation
> that would help me grok it fully?
I will take a chance by saying that

class << A
  def x...
  end
end

is the same as

class A
   def self.x
   end
end

although there might be some subtle differences

Do e.g, this
class << A
puts self
end
you can see kind of a Proxy object, but it behaves pretty much transparently.

Cheers
Robert

-- 
You see things; and you say Why?
But I dream things that never were; and I say Why not?
-- George Bernard Shaw