Learning Processing: A Beginner's Guide to Programming Images ...

8
8.1
Objects
“ No object is so beautiful that, under certain conditions, it will not look ugly. ”
—Oscar Wilde
In this chapter:
– Data and functionality, together at last.
– What is an object?
– What is a class?
– Writing your own classes.
– Creating your own objects .
– Processing “ tabs. ”
I’m down with OOP.
Objects 121
Before we begin examining the details of how object-oriented programming (OOP) works in Processing ,
let’s embark on a short conceptual discussion of “ objects ” themselves. It is important to understand that
we are not introducing any new programming fundamentals: objects use everything we have already
learned: variables, conditional statements, loops, functions, and so on. What is entirely new, however, is a
way of thinking, a way of structuring and organizing everything we have already learned.
Imagine you were not programming in Processing , but were instead writing out a program for your day, a
list of instructions, if you will. It might start out something like:
• Wake up.
• Drink coffee (or tea).
• Eat breakfast: cereal, blueberries, and soy milk.
• Ride the subway.
What is involved here? Specifi cally, what things are involved? First, although it may not be immediately
apparent from how we wrote the above instructions, the main thing is you , a human being, a person. You
exhibit certain properties. You look a certain way; perhaps you have brown hair, wear glasses, and appear
slightly nerdy. You also have the ability to do stuff , such as wake up (presumably you can also sleep), eat,
or ride the subway. An object is just like you, a thing that has properties and can do stuff .
So how does this relate to programming? Th e properties of an object are variables; and the stuff an object
can do are functions. Object-oriented programming is the marriage of everything we have learned in
Chapters 1 through 7, data and functionality, all rolled into one thing .
Let’s map out the data and functions for a very simple human object:
Human data
• Height.
• Weight.
• Gender .