cs231 Lecture Notes
Week 2, Monday

1) review of recursion, cont.

     mergesort -- leap of faith interpretation

     comment about interface design: modifiers and functions

     modifier: void method; just invoke it

	       Deck deck = buildDeck ();
	       shuffleDeck (deck);
	       sortDeck (deck);

     function: does not change the argument.  Returns new
     thing that (might) replace the old thing

	       	Deck deck = buildDeck ();
		shuffleDeck (deck);
		deck = mergeSort (deck);
		printDeck (deck);

	What happens if you forget the assignment?

	What happens to the old deck if you clobber it?


2) discussion of hw1

     what are classes for?

     (a) definition of new object (instance variables)
     (b) collection of related methods


Syntax issues pertaining to Homework 1:

       printDeck example from Section 12.0




Something new!!!

Object methods
--------------

Observation: lots of methods operate on a single object that
is passed on a parameter.

The object-oriented view of this is that you are invoking
a method "on" an object, or sometimes people say you are passing
a message to the object.

Either way, there is the notion that one of the parameters is
special.

OBJECT METHODS are an alternate syntax that makes the special
parameter invisible!


Object methods we have seen:

       g.drawOval (...);
       string.charAt (1);

When you invoke them, you invoke them "on" an object.

All the methods we have written have been CLASS METHODS.
You just invoke them.

Possible confusion:

	 Sometimes when you invoke a CLASS METHOD, you
	 specify the name of the class, as in

	 Card.printCard (...);
	 Math.cos (...);

How can we tell when we are invoking a CLASS or OBJECT method?


Ok, so how do we WRITE object methods?

1) leave out the word static!

2) leave out the magic parameter


In that case, how do we refer to the magic parameter?

1) using the keyword this

   OR

2) implicitly!

Examples:

	printDeck and printCard

plenty more examples in Chapter 13!