Lecture 21 Summary, CSE 341 Spring 2004

* Smalltalk look-up rules

* variables are lexically scoped and may resolve to fields or globals

* messages are second-class, searched from subclasses to superclasses

* late-binding (dynamic dispatch, virtual function call) is essential
  to OOP

* late-binding is not magic: we can use it as a pattern in Scheme and
  as a by-product get a good idea of how to implement it