Programming Perl, 4th Edition

What’s New in This Edition

What’s not new? It’s been a long time since we’ve updated this book. Let’s just say we had a couple of distractions, but we’re all better now.

The third edition was published in the middle of 2000, just as Perl v5.6 was coming out. As we write this, it’s 12 years later and Perl v5.16 is coming out soon. A lot has happened in those years, including several new releases of Perl 5, and a little thing we call Perl 6. That 6 is deceptive though; Perl 6 is really a “kid sister” language to Perl 5, and not just a major update to Perl 5 that version numbers have trained you to expect. This book isn’t about that other language. It’s still about Perl 5, the version that most people in the world (even the Perl 6 folks!) are still using quite productively.^[1]

To tell you what’s new in this book is to tell you what’s new in Perl. This isn’t just a facelift to spike book sales. It’s a long anticipated major update for a language that’s been very active in the past five years. We won’t list everything that’s changed (you can read the perldelta pages), but there are some things we’d like to call out specifically.

In Perl 5, we started adding major new features, along with a way to shield older programs from new keywords. For instance, we finally relented to popular demand for a switch-like statement. In typical Perl fashion, though, we made it better and more fancy, giving you more control to do what you need to do. We call it given–when, but you only get that feature if ...