Learning Python, 6th Edition

Chapter 4. Introducing Python Objects

This chapter begins our tour of the Python language. In an informal sense, in Python we do things with stuff. “Things” take the form of operations like addition and concatenation, and “stuff” refers to the objects on which we perform those operations. In this part of the book, our focus is on that stuff, and the things our programs can do with it.

Somewhat more formally, in Python, data takes the form of objects—either built-in objects that Python provides, such as strings and lists, or add-on objects we create with Python classes or external-language tools. As you’ll find, these objects are essentially just pieces of memory, with values and associated operations. Moreover, everything is an object in a Python script. Even simple numbers qualify, with values (e.g., 99) and supported operations (+, -, and so on).

Because objects are also the most fundamental notion in Python programming, this chapter gets us started with a survey that previews Python’s built-in object types. Later chapters in this part provide a second pass that fills in details we’ll gloss over in this survey. Here, our goal is a brief tour to introduce the basics.

The Python Conceptual Hierarchy

Before we get to the code, let’s first establish a clear picture of how this chapter fits into the overall Python picture. From a more concrete perspective, Python programs can be decomposed into modules, statements, expressions, and objects, as follows:

1. Programs are composed of ...