Programming Python, 3rd Edition

This Book’s Motivation

Over the 10 years since the first edition of this book was written, Python has transitioned from an emerging language that was of interest primarily to pioneers to a widely accepted tool used by programmers for day-to-day development tasks. Along the way, the Python audience has changed as well, and this book has been refocused with this new readership in mind. You will find that it is a nuts-and-bolts text, geared less toward introducing and popularizing the language and more toward showing you how to apply Python for realistically scaled programming tasks.

So, What’s Python?

If you are looking for a concise definition of this book’s topic, try this:

Python is a general-purpose, open source computer programming language optimized for quality, productivity, portability, and integration. It is used by hundreds of thousands of developers around the world in areas such as Internet scripting, systems programming, user interfaces, product customization, and more.

As a popular programming language that shrinks the development time, Python is used in a wide variety of products and roles. Counted among its current user base are Google, Industrial Light & Magic, ESRI, the BitTorrent file sharing system, NASA’s Jet Propulsion Lab, and the U.S. National Weather Service. Python’s application domains range from system administration, web site development, cell phone scripting, and education to hardware testing, investment analysis, computer games, and spacecraft control.

Among other things, Python sports OOP; a remarkably simple, readable, and maintainable syntax; integration with C components; and a vast collection of precoded interfaces and utilities. Its tool set makes it a flexible and agile language, ideal for both quick tactical tasks as well as longer-range strategic application development efforts.

Although it is a general-purpose language, Python is often called a scripting language because it makes it easy to utilize and direct other software components. Perhaps Python’s best asset is simply that it makes software development more rapid and enjoyable. To truly understand how, read on; we’ll expand on these concepts in the next chapter.

Since writing the first edition, I have also had the opportunity to teach Python classes in the U.S. and abroad some 170 times as of mid-2006, and this book reflects feedback garnered from these training sessions. The application domain examples, for instance, reflect interests and queries common among the thousands of students I have introduced to Python. Teaching Python to workers in the trenches, many of whom are now compelled to use Python on the job, also inspired a new level of practicality that you will notice in this book’s examples and topics.

Other book examples are simply the result of me having fun programming Python. Yes, fun. One of the most common remarks I hear from Python newcomers is that Python is actually enjoyable to use—it is able to both kindle the excitement of programming among beginners and rekindle that excitement among those who have toiled for years with more demanding tools. When you can code as fast as you can think, programming becomes a very different proposition and feels more like pleasure than work.

As you will see in this book, Python makes it easy to play with advanced but practical tools such as threads, sockets, GUIs, web sites, and OOP—areas that can be both tedious and daunting in traditional languages such as C and C++. It enables things you may not have considered or attempted with other tools.

Frankly, even after 14 years as a bona fide Pythonista, I still find programming most enjoyable when I do it in Python. Python is a remarkably productive and flexible language, and witnessing its application firsthand is an aesthetic pleasure. I hope this edition, as much as the two before it, will both demonstrate how to reap Python’s productivity benefits and communicate some of the excitement to be found in this rewarding tool.