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About This Book
This section underscores some important points about this book in general, regardless of its edition number. No book addresses every possible audience, so it’s important to understand a book’s goals up front.
This Book’s Prerequisites
There are no absolute prerequisites to speak of, really. Both true beginners and crusty programming veterans have used this book successfully. If you are motivated to learn Python, this text will probably work for you. In general, though, I have found that any exposure to programming or scripting before this book can be helpful, even if not required for every reader.
This book is designed to be an introductory-level Python text for programmers.* It may not be an ideal text for someone who has never touched a computer before (for instance, we’re not going to spend any time exploring what a computer is), but I haven’t made many assumptions about your programming background or education.
On the other hand, I won’t insult readers by assuming they are “dummies,” either, whatever that means—it’s easy to do useful things in Python, and this book will show you how. The text occasionally contrasts Python with languages such as C, C++, Java, and Pascal, but you can safely ignore these comparisons if you haven’t used such languages in the past
This Book’s Style and Structure
This book is based on training materials developed for a three-day hands-on Python course. You’ll find quizzes at the end of each chapter, and exercises at the end of the last chapter of each part. Solutions to chapter quizzes appear in the chapters themselves, and solutions to part exercises show up in Appendix B. The quizzes are designed to review material, while the exercises are designed to get you coding right away and are usually one of the highlights of the course.
I strongly recommend working through the quizzes and exercises along the way, not only to gain Python programming experience, but also because some of the exercises raise issues not covered elsewhere in the book. The solutions in the chapters and in Appendix B should help you if you get stuck (and you are encouraged to peek at the answers as much and as often as you like).
The overall structure of this book is also derived from class materials. Because this text is designed to introduce language basics quickly, I’ve organized the presentation by major language features, not examples. We’ll take a bottom-up approach here: from built-in object types, to statements, to program units, and so on. Each chapter is fairly self-contained, but later chapters draw upon ideas introduced in earlier ones (e.g., by the time we get to classes, I’ll assume you know how to write functions), so a linear reading makes the most sense for most readers.
In general terms, this book presents the Python language in a linear fashion. It is organized with one part per major language feature—types, functions, and so forth—and most of the examples are small and self-contained (some might also call the examples in this text artificial, but they illustrate the points it aims to make). More specifically, here is what you will find:
Part I, Getting Started
We begin with a general overview of Python that answers commonly asked initial questions—why people use the language, what it’s useful for, and so on. The first chapter introduces the major ideas underlying the technology to give you some background context. Then the technical material of the book begins, as we explore the ways that both we and Python run programs. The goal of this part of the book is to give you just enough information to be able to follow along with later examples and exercises.
Part II, Types and Operations
Next, we begin our tour of the Python language, studying Python’s major built-in object types in depth: numbers, lists, dictionaries, and so on. You can get a lot done in Python with these tools alone. This is the most substantial part of the book because we lay groundwork here for later chapters. We’ll also look at dynamic typing and its references—keys to using Python well—in this part.
Part III, Statements and Syntax
The next part moves on to introduce Python’s statements—the code you type to create and process objects in Python. It also presents Python’s general syntax model. Although this part focuses on syntax, it also introduces some related tools, such as the PyDoc system, and explores coding alternatives.
Part IV, Functions
This part begins our look at Python’s higher-level program structure tools. Functions turn out to be a simple way to package code for reuse and avoid code redundancy. In this part, we will explore Python’s scoping rules, argument-passing techniques, and more.
Part V, Modules
Python modules let you organize statements and functions into larger components, and this part illustrates how to create, use, and reload modules. We’ll also look at some more advanced topics here, such as module packages, module reloading, and the __name__ variable.
Part VI, Classes and OOP
Here, we explore Python’s object-oriented programming tool, the class—an optional but powerful way to structure code for customization and reuse. As you’ll see, classes mostly reuse ideas we will have covered by this point in the book, and OOP in Python is mostly about looking up names in linked objects. As you’ll also see, OOP is optional in Python, but it can shave development time substantially, especially for long-term strategic project development.
Part VII, Exceptions and Tools
We conclude the language fundamentals coverage in this text with a look at Python’s exception handling model and statements, plus a brief overview of development tools that will become more useful when you start writing larger programs (debugging and testing tools, for instance). Although exceptions are a fairly lightweight tool, this part appears after the discussion of classes because exceptions should now all be classes.
Part VIII, Advanced Topics (new in the fourth edition)
In the final part, we explore some advanced topics. Here, we study Unicode and byte strings, managed attribute tools like properties and descriptors, function and class decorators, and metaclasses. These chapters are all optional reading, because not all programmers need to understand the subjects they address. On the other hand, readers who must process internationalized text or binary data, or are responsible for developing APIs for other programmers to use, should find something of interest in this part.
Part IX, Appendixes
The book wraps up with a pair of appendixes that give platform-specific tips for using Python on various computers (Appendix A) and provide solutions to the endof-part exercises (Appendix B). Solutions to end-of-chapter quizzes appear in the chapters themselves.
Note that the index and table of contents can be used to hunt for details, but there are no reference appendixes in this book (this book is a tutorial, not a reference). As mentioned earlier, you can consult Python Pocket Reference, as well as other books, and the free Python reference manuals maintained at http://www.python.org for syntax and built-in tool details.
