ruby class vars and inheritance

gistfile1.txt

irb
1.8.7 :001 > class Foo
1.8.7 :002?>   class << self
1.8.7 :003?>     def setvar(val)
1.8.7 :004?>       @myvar = val
1.8.7 :005?>       end
1.8.7 :006?>     end
1.8.7 :007?>   end
 => nil 
1.8.7 :008 > class Bar < Foo
1.8.7 :009?>   end
 => nil 
1.8.7 :010 > Foo.setvar("foo")
 => "foo" 
1.8.7 :011 > Bar.setvar("bar")
 => "bar" 
1.8.7 :013 > Foo.instance_variable_get(:@myvar)
 => "foo" 
1.8.7 :014 > Bar.instance_variable_get(:@myvar)
 => "bar" 
1.8.7 :015 >