PETER J. SCOTT runs Pacific Systems Design Technologies, providing Perl training, application development, and enterprise systems analysis. He was a speaker on the 2002 Perl Whirl cruise and at YAPC::Canada, and he founded his local Perl Monger group. A software developer since 1981 and a Perl developer since 1992, he has also created programs for NASA's Jet Propulsion Laboratory. Scott graduated from Cambridge University, England, with a Master's of Arts Degree in Computer Science and now lives in the Pacific Northwest with his wife Grace, a cat, and a parrot, at least one of which also uses Perl. He is the lead author of Perl Debugged.
On it's face that makes it sound like you should pick up the book immediately. And for someone who is serious about Perl I think you should get this book. But there are still some faults. It could be a little better organized. And some of the common problems, like CGI scripts having embedded HTML, could be given more prominence and the text templating alternative given some more space. I looked in the tiny index for HTML::Template and found only two references, both of which were pretty short.
In what is probably both a curse and a blessing the book is not only about fixing legacy code. The majority of the book is about becoming a better Perl programmer and writing Perl as Perl. There are a few chapters and the beginning and end that are specifically about working with legacy code, but the majority of the book is practical insights into Perl coding styles using code fragments with effective exposition.
Small problems aside. This unique book is fun to read and is packed with valuable insights if you spend the time to look. The author obviously knows a lot about Perl and understands how to convey that knowledge to the reader effectively. If you are looking to maintain some Perl, or if you have hit a plateau in your understanding of Perl and you need a push to get to a higher level this book is for you.
Perl gets a lot of bad press from people who claim that it encourages people to write unreadable code. Whilst there's certainly a lot of very bad Perl code out there I think that's more a sign that it's used by a lot of people who don't know how to program than a reflection on the language itself. And that's where this book comes in. It assumes that you are familiar with the syntax of Perl but that you've never really been shown how to use it effectively. Which is a situation that many Perl programmers find themselves in.
Perl Medic is actually targetted at people who have to maintain older Perl code written by someone else, but I think that the information it contains is just as useful to anyone coding in Perl. Peter Scott has a lot of experience in writing Perl and in training other people to write Perl and the distillation of that experience and knowledge into these 300-odd pages mean that there are few Perl programmers who won't pick up something useful from this book.
The main emphasis in the book is on increasing the maintainability of code. The techniques are wide-ranging. I particularly enjoyed the examples of refactoring programs and the coverage of using modules from CPAN. Two other very good sections are the one on antipatterns in chapter 4 and the one on cargo cult programming in chapter 6. Together these sections give a programmer a number of easy to recognise quick wins when improving existing code and a checklist of things not to do when writing new code.
There are a couple of niggles. I've already mentioned that I think the book has been slightly mis-targetted and that it should have been aimed at anyone writing Perl code. The other problem that I had was that the medic analogy that runs through the book gets a bit strained at times. But these are only minor and they shouldn't prevent you from adding this book to your library.
In fact, all in all, the quote on the front cover is pretty accurate.