Like Topsy, Perl just grew, and as a result the need for a third edition came about. It's now over 1,000 pages, which it needs to be, as it performs several different duties. First, it's an introduction to the Perl language for those who are new to programming; also, it's a guide for those who are coming from other languages; and, finally, it's a Perl language reference.
Among Larry Wall's other pursuits is being a linguist, and it's perhaps for this reason that Perl is a peculiarly flexible language with many routes to achieving the same ends, as the authors ably demonstrate. It's also extensible in several ways, designed to work with many other languages. Also, as it's largely interpreted, programs written in Perl tend to run unmodified on a variety of platforms--although platform-specific Perl modules and programming practices are also discussed.
A major strength of Programming Perl is the way subject areas are approached from several directions. This constant shift of viewpoint eliminates blind spots in the reader's understanding and provides a pleasing echo of the way Perl itself can take many routes from here to there.
Because the Perl community is both knowledgeable and active, the language covers much more ground here than in the previous edition. Even if you have both previous editions, you'll want this latest version--if only for the new jokes. --Steve Patient, amazon.co.uk