Emilio>"...you may wish no to be bound to the internal struture of your
object within your very object itself. May be because your are not sure of
the internal shape your object would have."

Your desire is evidently a logical inconsistency.

Worse, it's actually easier to find and change all references to an instance
variable in all the methods of a class inheritance hierarchy than it is to
find and change all sends to self (and super) of a particular message--which
means that referencing the instance variable directly results in looser, not
tighter, binding.  Even better, if there's no method, then there can't be
any external sends of the message, so that that case doesn't even need to be
checked.

--Alan