Welcome to Python 3.1!
I've been working with Python for about ten years now, and every new version has caused me to fall in love with the language all over again. Version 3.1 is no different. If you are new to Python, rest easy — I'll guide you every step of the way. If, on the other hand, you are an old Python hand exploring the new version, the book is structured so that you can learn the new information you need, without wasting time on already-known information.
I wanted to write this book because I love Python. I love it! And I want to share my love with you. And, maybe you'll grow to love it as I do.
If you're computer-literate, and want to learn a fun programming language to better control your computer, this book is for you.
If you are a system administrator who wants to learn a great language to help you better manage and configure systems and networks, this book is for you.
If you already know Python, but are wondering what cool new features are available in version 3.1, this book is for you.
In summary, this book is for anyone interested in exploring Python programming with the newest and most full-featured, easy-to-use version, 3.1.
This book is designed to cover Python 3.1. Python 3.1, released in 2009, is the latest major revision of the Python programming language. Since Python is a cross-platform language, the content and examples in the book are applicable in any platform (unless specified otherwise). When there is a choice to be made as to platform independence, the examples will be as cross-platform as possible.
In addition, since Python 3.1 is relatively new, not all supporting libraries have been updated to work in Python 3.x. In those instances where this is the case and it is felt that the theory still needs to be expounded upon, Python 2.6 will be used in lieu of version 3.1.
As might be expected from a "Beginning" book, the book begins with an introduction to the language. From there, you'll move through the core of the language, then move on to more advanced and specialized topics. The book is divided up into four parts.
Part I — Dipping Your Toe into Python
The first part will allow you to, as the title suggests, dip your toe in.
First you'll be introduced to Python. This chapter will explore what Python is, and why it is so useful and powerful. Also explored will be Python's history from its early development to the newest version, which is the focus of this book. You'll also learn about the scope of Python's reach, and all the different areas of application development in which Python plays a part. Finally, you'll learn to work with your first data type — strings.
This chapter will guide you through the basics of working with numbers and operators. You will learn the different types of numbers, how to perform simple — and complex — equations, and work with the various operators. You will also learn about order of precedence and formatting numbers.
Ultimately, programming languages help you to manage different types of information — in other words, data. An understanding of data types and how they are represented in Python is essential to programming in Python. This chapter will help you to understand the best ways to represent different data types in Python.
Part II — Python Language and the Standard Library
Of course, the core piece of knowledge you need to use a language is to know the language itself, and familiarize yourself with its syntax and modules. This part will start small, with data types and variables, and gradually introduce additional concepts until you have all the information you need to develop fully functional Python programs.
You'll want to read through these chapters sequentially — each chapter builds on the information presented in the previous chapter.
Ultimately, there will come a point when your program must make a decision — do I take this path or that path? And what happens when I take that path? In this chapter, you will learn how to compare data, such as deciding if one value is greater than another, and use repetition to repeat repetitive tasks.
This chapter will help you to expand on your Python knowledge by introducing you to functional programming. Functions allow you to take advantage of powerful concepts like parameter passing and code reuse. You'll learn how to use functions to make your code more efficient and flexible.
Here you will be shown what objects are and learn to create classes. You will learn how to define them, create objects in your classes, write methods, and discuss the scope of your objects.
When your programs get larger, you'll want to divide them up into separate components. This chapter will discuss Python modules. You'll also explore packages, which are nothing but collections of modules.
An important part of everyday programming is learning to work with files and directories. This chapter focuses on creating, modifying, and working with files in general. In addition, you will learn how to obtain data from files and how to interact with the various directories.
Here you will learn about some of the other features the language has to offer, including how to make decisions with lists, string substitutions with dictionaries, and some of the featured modules.
Modules help you save time by allowing you to reuse snippets of code. It also ensures fewer errors, as the module you use will have been tested and used many times before. Here, we will learn to create our own modules, as well as import and work with pre-existing modules — something that makes Python particularly powerful.
There are so many things you can do with text in programming and in essence, text is the key to effectively communicating with your user. After all, without it, the only thing you are left with is images. In this chapter you learn to process text in a variety of ways, including: working with regular expressions, searching for files, and searching for files of a particular type.
Part III — Putting Python to Work
So, now that you know what Python is, and how to work with the language, what's next, you ask? This final part explores many of the programming topics you'll likely encounter or want to explore. These can be looked at sequentially, or in any order you like ... these chapters are independent of each other.
There is only one way to ensure your program works before it is in the hands of the user, and that is by testing your program. Here, you will learn not only the concepts behind properly testing your programs, but the tools and frameworks available to you.
Thus far in the book, all the programs work through the command line. In this chapter, you'll be introduced to the concept of GUI programming. You'll also walk through creating a few GUI programs with Tkinter, the most popular GUI toolkit used by Python programmers.
Databases store information that your program can use for an infinite amount of reasons. It also acts as a place for you to store information, and later retrieve that information for a given task. In this chapter you learn about the different types of databases and how to work with them.
XML is a powerful tool for processing data on the Internet. Here, you will learn the basics of XML including the difference between schema and DTD, basic syntax, how to create and validate your own XML, and more advanced topics such as using lxml.
Now that the Internet has wormed its way into our everyday lives, and has become more of a necessity than a privilege, learning to programmatically send e-mails and allow users to communicate across the web is essential. In this chapter, you will learn how to do just that.
This chapter delves into programming with the C language, including working with C frameworks and modules, the basics of C, and passing parameters from Python to C, and then returning value back to Python.
Numbers were touched on briefly in the beginning of this book; now it is time to delve more deeply below the surface. Here you will learn all there is to know about integers and floating point numbers, as well as complex numbers, arrays, and working with built-in math functions and modules.
Django is a web application framework written in Python, which utilizes the model-view-architecture pattern. Originally created for managing news websites, Django has become popular for its ease of use, allowing programmers to create complex websites in a simple fashion, including database-focused sites. Here we will learn the basics of Django.
Here you will learn the foundations of working with web applications and web services. You will learn about the REST architecture, as well as how to work with HTTP Requests and Responses.
Part IV: Appendices
In the back of the book, there are some useful appendices to further your knowledge and fun with Python:
Answers to the Exercises
Online Resources — where do you go from here?
What's New in Python 3.1
Glossary of terms
There are some minimal requirements to use the material in this book. The following are recommendations, as Python itself runs on many different platforms. However, the first chapters assume that you have access to a GUI such as is available in Windows, Mac OS X, or the X Window system on UNIX and Linux. Naturally, some chapters, such as the GUI chapter, require the GUI as well, and chapters involving networking will make much more sense if a network connection is in place.
Following are the suggested minimum requirements:
A PC running Linux, a BSD UNIX, or Windows running at 500MHz or faster, or a G3 or later Macintosh running Mac OS X version 10.2 or later
256MB of memory (at a minimum)
A graphical user interface native to the platform you are on
Necessary access to the computer you are on so that you may install required software
Network access to a TCP/IP network such as the Internet or a campus network
Internet access to download required software
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