Perl Medic : Transforming Legacy Code

Rating:
Summary: One of the best Perl books out there
Review: A quote on the front cover of this book says "if you code in Perl then you need to read this book". That's a pretty bold claim to make. It made me think of the hyperbole on covers of books that claim to teach you to program in Perl in just a few days. But this book is published by Addison Wesley, who are a well respected technical publisher of technical books and the quote is from Adam Turoff who certainly knows what he's talking about when it comes to Perl programming. So in this case the claim isn't hyperbole. The book really is one that I want every Perl programmer to read.

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.

Rating:
Summary: One of the best Perl books out there
Review: A quote on the front cover of this book says "if you code in Perl then you need to read this book". That's a pretty bold claim to make. It made me think of the hyperbole on covers of books that claim to teach you to program in Perl in just a few days. But this book is published by Addison Wesley, who are a well respected technical publisher of technical books and the quote is from Adam Turoff who certainly knows what he's talking about when it comes to Perl programming. So in this case the claim isn't hyperbole. The book really is one that I want every Perl programmer to read.

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.

Rating:
Summary: A "must have" for every Perl beginner...
Review: I wish I read this book earlier...
In fact it's my only regret about this book...

This book is an absolute "must have" for every Perl beginner.
Teaching how to program safely, and to maintain/debug/clean Perl code is not an easy goal, but the author
(who is obviously someone who loves and knows Perl)
manages to do it in a simple and pragmatic style.

A lots of subject are covered too many to mention here
(you HAVE to read this book anyway ;-) )
but I'd like to point the chapter about "cargo cult programming" which will be highly useful to beginners to my mind
(So sad the cargo cult constructor isn't described too (you know the one using : my $class = ref $proto || $proto; ))

While oriented to the beginners (IMHO), the experienced Perl coder will also probably find some useful tricks.
(Useful modules, uncommon options or other pieces of code that increase your productivity...)

In short this book is pure "Perl Packaged Experience", save you hours of trial&error frustration and buy this book, you won't regret it...


Rating:
Summary: This is a very good book
Review: The book is supposedly about "transforming legacy code," but what it teaches is actually much broader. It demonstrates a set of "best practices" for creating and maintaining large Perl projects, and it explains very clearly why these practices are best, and how they will benefit your project.

Because it is well written and well considered-- and above all, practical-- you will put much of what you learn to work right away.

Of particular interest are the chapters on testing (Chapter 3) and using CPAN modules (Chapters 8 and 9). The author spends quite a few pages explaining Perl's Test modules and demonstrating how to use them. This chapter alone is worth the price of the book, and will save you hours (or days) of debugging time.

The chapters on CPAN modules are equally useful because they point out some of the freely available modules that can save you a considerable amount of development time. The author takes the time to explain what each module can do, and in some cases gives examples of how to use them.

Chapter 9 describes modules that may be particularly useful during development, including modules for explaining regular expressions, benchmarking and profiling code, and finding dead code.

Other interesting chapters include:

- the opening chapter of the book, which lays out a plan of action for working with other programmers within an organization when you have inherited a mess of legacy code.

- a chapter that details specific changes between different versions of Perl, so that you can know exactly when certain features became a part of the language, and exactly which constructs, pragmas, etc. will work (or not work) with each version of Perl

Most of the book describes how to apply good programming practices within the Perl language: encapsulation, modularity, maintainability, clarity of style and efficiency of code. Perl includes pragmas, modules, and mechanisms to support these practices, though you may not have known this from reading the usual Perl books.

Overall, this book is very useful for intermediate to advanced Perl programmers, for anyone having to maintain legacy Perl code, and for anyone considering writing Perl applications of even moderate complexity.

Rating:
Summary: A good book with a misleading title
Review: While the "medic" metaphor recurs throughout the book, most of the material isn't directly related to repairing old code. Instead, this is a collection of best practices for new code. (The author recommends rewriting existing code if at all possible.) It ends up resembling another excellent Perl title, Joseph Hall's Effective Perl Programming. Good company to keep. Perl Medic has the advantage of being newer, and of covering a bit more material. The writing style is very easy to read, and the order of presentation works well. An excellent title for any intermediate-level Perl programmer.

Rating:
Summary: Novel and effective tutorial in solid Perl Programming
Review: You can learn a lot from books (or so it seems), but you can't learn a feel for the language. I had read all of the O'Reily Perl books and found myself in charge of a large Perl project writing new code. I hired on a real Perl guru and he taught me a ton, in person, about how to write Perl as Perl and do it well. What amazes me about Perl Medic is how much of what the Perl guru taught me is in this book. It's as if I had the man by my side again.

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.