Object messages
          The messages described in this section provide low-level access to the instance variables of an object.
          Primitive accessing
          instVarAt:, instVarAt:put:, instVarNamed:, instVarNamed:put: 
          Note:
          The Blue Book does not define instVarNamed: and instVarNamed:put:, but they seem to provide useful function analogous to the other 2 messages and so have been included.
         
        
          Last modified date: 01/29/2015