Wicked Cool Perl Scripts

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This book review was published by Slashdot, 2006-06-28.

Wicked Cool Perl Scripts

Of all the popular programming languages now in use, Perl is perhaps the best suited for writing utilities — for several reasons, such as its text processing capabilities, ease of addressing system resources, and minimal language overhead for input, output, list processing. It was designed to blend the rapid solution development of shell scripting, with the powerful control constructs of third-generation languages. Consequently, Perl quickly became a favorite language for developing programs ranging from system administration utilities to CGI scripts that power websites. In fact, Perl has been called the glue that holds the Internet together. The tremendous flexibility and power of Perl is seen in Steve Oualline's book Wicked Cool Perl Scripts: Useful Perl Scripts That Solve Difficult Problems.

Published by the cleverly named No Starch Press, Wicked Cool Perl Scripts comprises 336 pages, spanning 11 chapters, with a brief introduction, as well as an index. The book appeared in February 2006, and was published under the ISBN of 978-1593270629. No Starch Press maintains a Web page for the book, where readers can find a sample chapter (the third one, covering CGI debugging), in PDF format. There is a link for downloading all of the source code, as well as links for purchasing the book in paper form, or PDF, or both (at a discount of almost $15).

The book presents 47 scripts, grouped into 11 categories: general-purpose utilities, website management, CGI debugging, CGI programs, Internet data mining, Unix system administration, picture utilities, games and learning tools, development tools, mapping, and regular expression graphing. The scripts perform such functions as finding duplicate files on your PC, converting currencies, processing error logs, generating jokes randomly, getting stock quotes, and managing photos and other images. Some of the scripts play games, while others would be invaluable to any Linux or Unix system administrator. For readers with their own websites, the book offers scripts for verifying links, locating orphan files, detecting hackers, and locking them out. In addition, there is a script for counting the number of visitors to your site, and even one for presenting a guest book. Software developers will find the material valuable, as there are Perl scripts for generating code, locating dead code, and handling regular expressions — parsing and graphing them.

The scripts themselves are fairly wide ranging in complexity and size, with a few fitting on a single page of the book, while others requiring more than ten pages. Fortunately, the scripts generally contain enough comments so as to be clear in how they work to any programmer comfortable with the language. Nonetheless, the author explains how to run each script, what sort of results the reader should see, how the script works, and what modifications one might want to make to it ("hacking the script"). In addition, every one of the scripts contains a POD (Plain Old Documentation) section, though only in the downloadable version — not the version seen in the book, to save space.

It is doubtful that any beginning Perl programmer might mistake this book as a Perl primer or reference. The title alone makes clear that the focus is on the offered scripts themselves, and their ability to help the reader solve common problems. On the other hand, Perl programmers of any level of fluency with the language, would benefit from reading through the scripts, as well as the author's explanation of how they address and solve each problem. I myself have been programming in Perl for ages, and yet I spotted CPAN modules that I can use in my own Perl scripts in the future.

The value of the scripts themselves to each individual reader, naturally depends upon what sort of tasks the reader would like to accomplish with Perl. The 11 categories of scripts are varied enough so as likely to be of use to just about anyone who would like to use the "Swiss Army knife of languages" for getting the job done on their computer, or that of their employer (as a system administrator). Personally I found most useful the scripts for detecting changed files, scanning websites for dead links, and parsing regular expressions.

There are other aspects to like about this book. It has a RepKover binding, to lay flat when open. The illustrations are clear and not excessive in number. Unlike some technical authors, whose weak attempts at humor simply make their obtuse material more annoying, Oualline is more subtle, such as his reference to the cost of Microsoft Windows CDs in a Hong Kong shop, or "Ingesting a Cheerio nasally". Well, perhaps not always subtle, but invariably welcome in what could otherwise be an extremely dry subject.

Like any book, there are some areas for improvement, perhaps in future editions: In the illustrations that employ rays pointing from one node to the next, some of the curved rays are remarkably jagged, as if they were not computer-generated. Far more importantly, some of the scripts could benefit from more internal comments, as well as having the code broken up into smaller functions, which improves clarity and maintainability. Also, some of the variables and functions could use more descriptive names. For instance, using two examples from a randomly chosen page: $file_name would be more clear than $cur_file (is it the file's name, full path, or contents?). print_file_cell() would be better than do_file() (do what to the file?).

But aside from those weaknesses, Wicked Cool Perl Scripts is a fine book that would be of interest to any Perl programmer, regardless of their expertise. In fact, the administrator of a website or a Linux/Unix server, would not even have to know the language in order to download these Perl scripts, and use them to solve problems on the job.

Copyright © 2006 Michael J. Ross. All rights reserved.

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