Chapter 6. Oh Oh: Objects and Classes
No object is mysterious. The mystery is your eye.
Elizabeth Bowen
Take an object. Do something to it. Do something else to it.
Jasper Johns
Up to this point, you’ve seen data structures such as strings and dictionaries, and code structures such as functions and modules. In this chapter, you’ll deal with custom data structures: objects.
What Are Objects?
As I mention in Chapter 2,
everything in Python,
from numbers to modules,
is an object.
However, Python hides most of the object machinery
by means of special syntax.
You can type num = 7
to create a object of type integer with the value 7,
and assign
an object reference to the name num.
The only time you need to look inside objects is
when you want to make your own or modify the behavior of existing objects.
You’ll see how to do both in this chapter.
An object contains both data
(variables, called attributes)
and code (functions, called methods).
It represents a unique instance of some
concrete thing. For example, the integer object with the value
7 is an object that facilitates methods
such as addition and multiplication,
as is demonstrated in “Numbers”.
8 is a different object.
This means there’s an Integer class in Python,
to which both 7 and
8 belong.
The strings 'cat' and 'duck' are also objects
in Python, and have string methods that
you’ve seen, such as capitalize() and replace().
When you create new objects no one has ever created before, you must create a class that indicates ...
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