Learning Python - Mark Lutz [18]
I also want to thank my original editor at O’Reilly, the late Frank Willison. This book was largely Frank’s idea, and it reflects the contagious vision he had. In looking back, Frank had a profound impact on both my own career and that of Python itself. It is not an exaggeration to say that Frank was responsible for much of the fun and success of Python when it was new. We still miss him.
Finally, a few personal notes of thanks. To OQO for the best toys so far (while they lasted). To the late Carl Sagan for inspiring an 18-year-old kid from Wisconsin. To my Mom, for courage. And to all the large corporations I’ve come across over the years, for reminding me how lucky I have been to be self-employed for the last decade!
To my children, Mike, Sammy, and Roxy, for whatever futures you will choose to make. You were children when I began with Python, and you seem to have somehow grown up along the way; I’m proud of you. Life may compel us down paths all our own, but there will always be a path home.
And most of all, to Vera, my best friend, my girlfriend, and my wife. The best day of my life was the day I finally found you. I don’t know what the next 50 years hold, but I do know that I want to spend all of them holding you.
—Mark Lutz Sarasota, FloridaJuly 2009
Part I. Getting Started
Chapter 1. A Python Q&A Session
If you’ve bought this book, you may already know what Python is and why it’s an important tool to learn. If you don’t, you probably won’t be sold on Python until you’ve learned the language by reading the rest of this book and have done a project or two. But before we jump into details, the first few pages of this book will briefly introduce some of the main reasons behind Python’s popularity. To begin sculpting a definition of Python, this chapter takes the form of a question-and-answer session, which poses some of the most common questions asked by beginners.
Why Do People Use Python?
Because there are many programming languages available today, this is the usual first question of newcomers. Given that there are roughly 1 million Python users out there at the moment, there really is no way to answer this question with complete accuracy; the choice of development tools is sometimes based on unique constraints or personal preference.
But after teaching Python to roughly 225 groups and over 3,000 students during the last 12 years, some common themes have emerged. The primary factors cited by Python users seem to be these:
Software quality
For many, Python’s focus on readability, coherence, and software quality in general sets it apart from other tools in the scripting world. Python code is designed to be readable, and hence reusable and maintainable—much more so than traditional scripting languages. The uniformity of Python code makes it easy to understand, even if you did not write it. In addition, Python has deep support for more advanced software reuse mechanisms, such as object-oriented programming (OOP).
Developer productivity
Python boosts developer productivity many times beyond compiled or statically typed languages such as C, C++, and Java. Python code is typically one-third to one-fifth the size of equivalent C++ or Java code. That means there is less to type, less to debug, and less to maintain after the fact. Python programs also run immediately, without the lengthy compile and link steps required by some other tools, further boosting programmer speed.
Program portability
Most Python programs run unchanged on all major computer platforms. Porting Python code between Linux and Windows, for example, is usually just a matter of copying a script’s code between machines. Moreover, Python offers multiple options for coding portable graphical user interfaces, database access programs, web-based systems, and more. Even operating system interfaces, including program launches and directory processing, are