ok, i've got some module and it has some instance variables i want to
be set by the classes extending the module, and aparently i'm not doing
this correctly:


module A
  def test
    raise 'ARG' if !@blah
    @blah
  end
end

class B
  include A
  extend A
  @blah = 'YES!'
end



irb(main):025:0> b = B.new
=> #<B:0x136376c>
irb(main):026:0> b.test
RuntimeError: ARG
        from (irb):9:in `test'
        from (irb):26


can anyone tell me what the syntax should be? how do i set @blah in the
B class so that its available to the test method