From: German Monfort <monfort.german@...>
Date: 2007-05-01T02:52:58+09:00
Subject: Re: Class Level Variables

> 2) Class variables are associated with a class *and* its subclasses
> and the order of initialization is important.
>
> class C
>    @@foo = 42        # shared by C and its decendents!
>    def foo
>      @@foo           # shared with C, D, and E
>    end
>    def bar
>      @@bar           # this is C's @@bar
>    end
> end
>
> class D < C
> end
>
> class E < C
>    @@foo = 43        # @@foo shared with C, D, and E
>    @@bar = 44        # @@bar only defined for E
>    def bar
>      @@bar           # this is E's @@bar
>    end
> end
>
> puts D.new.foo       # 43
>
> puts E.new.bar       # 44
> puts C.new.bar       # undefined!
>
> class C
>    @@bar = 45
> end
>
> puts C.new.bar       # 45
> puts E.new.bar       # still 44
>
> Gary Wright
Shouldn't be 
puts D.new.foo � � � # 42 ?

Because D < C and has no foo method defined (so it uses C' foo) and also has 
no @@foo defined (so it uses C's @@foo) which is set to 42 not 43.
I'm confused here.