6.001 Recitation #12 – March
19, 2003
RI: Konrad Tollmar
•Basic Object System
Class:
specifies the common behavior of entities
in scheme, a "maker" procedure
Instance:
A particular object or entity of a given class
in scheme, an instance is a message-handling procedure made by the maker procedure
1. A Car maker
Write a HOP car-maker that create a message-handling procedure
, and maintain the states type and running. You should be able to get these states through the message type? and run? And you should be able to change the state running through the messages start and stop.
2. A Painter
Specify a Painter class that could set-up a paint area, and draw on that area using different colors. Use a Class diagram to specify the class, implement the class, and show with some instance diagrams how to create instances from this class.
3. A drawing program
Specify with an object-oriented model a drawing program. Use a class diagram to specify needed classes, and show how the classes relate to each other.