CSC223 2004F, Class 24: OOD Heuristics (2): Relationships

Admin:
* SAM TANG IS SOMETHAT DEAD MEAT
* Missing or late: Evan, others
* Should Jesse be permitted to design a four-year plan that includes no humanities outside of foreign language and no social studies?  Yes, as long as SamR is not his advisor.
* Take-home exam 1 assigned (and discussed)
* In-class exam next Monday
  * Closed book (one hand-written page of notes permitted)
  * Written
  * Conceptual (I hope)
* Why both kinds of exams?
  * Test different skills.
  * Final will be in-class, so at least one in-class is helpful.
* Friday's homework (draw pretty pictures) is week 10's homework
  (Talk about slipping schedules.)
* Questions on that homework?  
  * Bring 'em on Friday
  * How should we do it?  Override the paintComponent method for some component of your choice (probably a JLabel)
  * Two possible designs:
    * One big JLabel, each tile drawn at a different place
    * One JLabel for each tile
* Topic for Friday: Graphics!  Fun fun fun.

Overview:
* Preliminaries
  * Questions on the reading?
  * QUIZ!
* Basics:
  * Ways in which classes/objects relate to each other
  * Obtaining classes to use
* Class Design
* Inheritance
* Polymorphism
* Association

/Questions: What didn't you understand?/

What's the difference between containment and association?
* In some languages, when you have an object as a field, you actually contain that object
public class Foo {
  int x;
}
public class Bar {
  Foo foo;
}
* In some languages:  The memory allocated to a Bar includes memory for a Foo
* In other languages (such as Java), all objects are stored by reference, in which case the memory allocated to a Bar includes only space for a reference to a Foo.
* In languages which have "real containment" (memory includes memory for the contained field), the first kind of thing is "containment" and the second is "association"
* In Java, all containment is association

Are there ever cases in which X is part of Y and Y is part of X?
* There may be, but they'll be a really hard thing to model in some object-oriented languages.
* Such things will be handled by association-type containment
* A vector of things that contain vectors sort of fits, but the two "vectors" are different

QUIZ TIME!
* TITLE IT: "Quiz on Surreptitious Case Analysis"
* What is "explicit case analysis" mentioned in 5.12 and 5.13 and many other places in the text?
* What is "surreptitious coupling"?  How does it relate to the other kinds of coupling?
* If you don't know an answer, you can say so and explain why you didn't ask during question time.
* When you finish, you may leave.

Answers on Friday