From: "David A. Black" <dblack@...>
Date: 2003-12-04T03:23:59+09:00
Subject: Re: Attempted roadmap of future instance variables....

Hi --

On Thu, 4 Dec 2003, Robert Klemme wrote:

> 
> "David A. Black" <dblack@wobblini.net> schrieb im Newsbeitrag
> >   class A
> >     def m
> >       instance_variable_set("@x",1)
> >       instance_variable_set("@_y",2)
> >     end
> 
> This is all well, but what if you invoke those methods from the outside?

OK, I think this illustrates your question (and a conjectural answer
:-)

Given this:

  class M
    def y1
      @_y
    end
  end

  class N < M
    def y2
      @_y
    end
  end

if we do this:

  n = N.new
  n.instance_variable_set("@_y",100)

which @_y got set?  In other words, what will the two @_y-getters give
us?

  puts n.y1    # M's view of n's @_y
  puts n.y2    # N's view of n's @_y

I would tend to assume that we'd get

  nil
  100

i.e., that instance_variable_set, if it has to choose a class-local
scope as well as instance scope, would choose the object's "birth
class".  But I'm not certain.  


David

-- 
David A. Black
dblack@wobblini.net