Because this book’s examples form much of its content, I want to say a few words about them up front.
As before, examples, updates, corrections, and supplements for this book will be maintained at the author’s website, which lives officially at the following URL:
This page at my book support website will contain links to all supplemental information related to this version of the book. Because I don’t own that domain name, though, if that link ceases to be during this book’s shelf life, try the following alternative site as a fallback option:
|http://learning-python.com/books/about-pp4e.html (alternative location)|
If neither of those links work, try a general web search (which, of course, is what most readers will probably try first anyhow).
Wherever it may live, this website (as well as O’Reilly’s, described in the next section) is where you can fetch the book examples distribution package—an archive file containing all of the book’s examples, as well as some extras that are mentioned but not listed in the book itself. To work along without having to type the examples manually, download the package, unpack it, and consult its README.txt file for usage details. I’ll describe how example labels and system prompts in this book imply file locations in the package when we use our first script in the first chapter.
As for the first three editions, I will also be maintaining an informal “blog” on this website that describes Python changes over time and provides general book-related notes and updates that you should consider a supplemental appendix to this text.
O’Reilly’s website for this book, described later in this Preface, also has an errata report system, and you can report issues at either my site or O’Reilly’s. I tend to keep my book websites more up to date, but it’s not impossible that O’Reilly’s errata page may supersede mine for this edition. In any event, you should consider the union of these two lists to be the official word on book corrections and updates.
The examples in this book were all developed, tested, and run under Windows 7, and Python 3.1. The book’s major examples were all tested and ran successfully on the upcoming Python 3.2, too (its alpha 3 release), just before the book went to the printer, so most or all of this book applies to Python 3.2 as well. In addition, the C code of Chapter 20 and a handful of parallel programming examples were run under Cygwin on Windows to emulate a Unix environment.
Although Python and its libraries are generally platform neutral, some of this book’s code may require minor changes to run on other platforms, such as Mac OS X, Linux, and other Unix variants. The tkinter GUI examples, as well as some systems programming scripts, may be especially susceptible to platform differences. Some portability issues are pointed out along the way, but others may not be explicitly noted.
Since I had neither time nor budget to test on and accommodate all possible machines that readers might use over the lifespan of this book, updates for platform-specific behaviors will have to fall into the suggested exercises category. If you find a platform dependency and wish to submit a patch for it, though, please see the updates site listed earlier; I’ll be happy to post any platform patches from readers there.
The book examples package described earlier also includes portable example demo launcher scripts named PyDemos and PyGadgets, which provide a quick look at some of this book’s major GUI- and Web-based examples. These scripts and their launchers, located at the top of the examples tree, can be run to self-configure program and module search paths, and so can generally be run immediately on compatible platforms, including Windows. See the package’s README files as well as the overviews near the end of Chapters 6 and 10 for more on these scripts.
We now interrupt this Preface for a word from the legal department. This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.
We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: “Programming Python, Fourth Edition, by Mark Lutz (O’Reilly). Copyright 2011 Mark Lutz, 978-0-596-15810-1.”