From: Phrogz <phrogz@...>
Date: 2007-08-17T03:59:57+09:00
Subject: Re: Does singleton variables have any meaning ?

On Aug 16, 10:25 am, Alex Young <a...@blackkettle.org> wrote:
> Arno J. wrote:
> > class A
> >   @class_instance_variable
> >   class << self  #or class << A
> >     @singleton_variable # <- Can this be used/called elsewhere ?
> >     def some_method
> >       @class_instance_variable
> >     end
> >   end
> > end


> class A
>    class << self
>      @singleton_variable
>      attr_accessor :singleton_variable # <----- N.B.
>    end
> end
> irb(main):035:0> A.singleton_variable = :foo
> => :foo
> irb(main):037:0> A.singleton_variable
> => :foo

Your accessor method there is referencing a new class-level instance
variable, that is in a different scope than your (no-op)
@singleton_variable line there.

irb(main):001:0> class A
irb(main):002:1>   @foo = 1
irb(main):003:1>   class << self
irb(main):004:2>     @foo = 2
irb(main):005:2>     attr_accessor :foo
irb(main):006:2>   end
irb(main):007:1> end
=> nil
irb(main):008:0> A.foo
=> 1