CS100, Spring 2000, Exercise 6: I Want My Privacy!
Due in lecture Tuesday, April 4

Concept: Encapsulation

What to turn in: 

    A printout of your revision of our core solution to Project 5,
    with your changes CLEARLY MARKED.

What to do:

    Make ALL instance variables $private$.

    For succinctness --but not completeness-- define getters/setters only
    as necessary for the program to work.

Helpful Notes:

    Methods may have the same name as instance variables:
    methods are distinguished from variables by virtue of 
    the parentheses used to invoke them.

    Method $getSize$ is already defined for class $Frame$ and hence
    for class $World$, but you can use $getsize$ or the observation
    above.