214 ;;Quote: objects in computer languages should match natural mechanisms for storing and using real world knowledge

214 ;;Quote: can represent a set by its essential properties or by a prototypical example

214+;;Quote: if use prototypical examples for sets, describe other members by how they differ from the prototype

215 ;;Quote: while a set is defined by its members or defining characteristics, difficult to do in practice; we typically create new concepts from examples

215 ;;Quote: prototypes are good for expressing defaults; e.g., Fred is like Clyde but white, instead of, Fred is an exceptional, white elephant

215 ;;Quote: use delegation and prototypes to remove the distinction between class and instance

215 ;;Quote: if want some object to share knowledge with a prototype, it delegates messages to the prototype that it can't handle

216 ;;Quote: can define methods, variables, and extensions as objects in their own right

216 ;;Quote: in object-oriented systems, a variable is an object that remembers a name and a value, and responds to access and modification messages

216 ;;Quote: a class method is a system object that only responds to messages for which it is designed

216 ;;Quote: an extension object uses delegation to forward a message to an appropriate receiver

218 ;;Quote: it is easy to implement inheritance with delegation of messages, but not vice versa