Hi,

In message "Re: Security problems"
    on 03/01/10, Tim Bates <tim / bates.id.au> writes:

|Anything less than that and it's not really demonstrating OOP.
|So I guess what I really want to do is give a piece of code all the 
|restrictions of $SAFE == 4 with one exception - permission to extend one 
|particular class. I can't see a simple way to do this, but maybe I'm missing 
|something.

There's no restriction to create subclass in $SAFE level 4.
The point is constant assignment.  Wrap with a tainted module for
example.

  class Foo
  end

  module XXX
    self.taint
    Thread.start do
      $SAFE=4
      class Bar<Foo
      end
    end.join
  end

							matz.