Programming Ruby

There are a few different editions of this book. The version I read is the second edition, written by Dave Thomas with Chad Fowler and Andy Hunt and published in 2005, covering Ruby 1.8.2. There's now a fourth edition, covering Ruby 1.9 and 2.0, which is probably what you'd want if you were buying this book today. This book, in whatever edition, is called the Pickaxe in the Ruby community after its cover.

I've used a lot of different programming languages, so I can usually pick one up on the fly reasonably well, but I still like to read a good introductory book before using one seriously. It's a bit too easy to get lost or to fall into habits that don't match the best practices of the language community without a solid introduction. I've been using a bit of Ruby off and on since I started using Puppet, but I'm looking at doing more serious development using Chef, so I decided it was time to get that introduction. (It helped that I had this book sitting around, although that's also why I read an older edition.)

Programming Ruby starts with the obligatory introduction to installing and running Ruby, and then provides a high-level introduction to the language and its basic types — just enough to make Ruby comprehensible before starting into the object system. Everything is an object in Ruby, so the book introduces the object system as early as possible, and then shows the rest of the language from constants up in the light of that object system. The rest of part one follows the normal language introduction path, building up from constants and methods to exceptions, modules, and basic IO. It closes with chapters about threads and processes, unit testing, and the debugger.

Part two is a grab-bag of one-chapter topics describing how to use Ruby in a particular setting, or showing one angle of the language. The best of those chapters for me was the one on RDoc, partly because I'm quite impressed by Ruby's documentation system. A few of these chapters are oddly in-depth for an introductory book — I doubt I'm ever going to use all the details about special irb configuration, and if I do, I'd just look them up — but I greatly appreciated the solid chapter on how to write Ruby extensions in C. There is also the obligatory chapter on writing GUI applications with Tk, which always seems to show up in these sorts of introductions and which always baffles me. Does anyone actually do this any more instead of writing a web application?

Part three dives back into the language and provides a more complete and formal description. The authors aren't afraid to get into some of the internals, which I appreciated. There is a good chapter here on the details of the type system and how objects and classes interact, and a much-needed extended discussion of duck typing. This type of weak typing and runtime binding is fundamental to how Ruby approaches objects, for better or worse. (I have mixed opinions; it makes some things easier, but I increasingly appreciate strong typing and more formal interface definitions.) Some discussion of marshalling and introspection closes out the discussion portion of the book.

That's about 420 pages of the material. The rest of the book is a detailed reference on all of the core classes, and a quicker overview of the standard library. Normally, this sort of thing is thrown into language introductions to pad out the page count, but usually the language's official documentation is better at this sort of reference. But I found Programming Ruby to be an exception. The reference is succinct, sticking to a paragraph or two for each method, and did a great job of providing enough cross-reference and discussion to put each class into a broader perspective. It's the most useful example of this type of reference section I've seen. I still probably won't use it after this initial reading, but I think I got a better feel for the language from reading through it.

It's hard to review a book like this without reviewing the language it documents, at least a little bit. I'll indulge: it entertains me how much Ruby is obviously based on Perl, including borrowing some of Perl's more dubious ideas. The global punctuation variables will look familiar to any Perl programmer, and the oddly-named global variables for the interpreter flags are in the same spirit. The language unfortunately has similar problems as Perl with safely running commands without using the shell; it's possible, but not the default and not what the built-ins do. There are places where I wish Ruby were a little less like Perl.

The plus side for an experienced Perl programmer is that Ruby feels quite familiar and has made some clear improvements. The ? and ! convention for methods that return booleans or modify objects in-place is brilliant in its simplicity, and something I'd love to see in more languages. And the way Ruby implements ubiquitous code blocks for both iterators and for any temporary objects is lovely once one gets used to it. It's similar to Python's context managers, except more general and built deeper into the language. Returning to the review of the book, rather than the topic, Programming Ruby has a good, clear explanation of blocks, iterators, and yield.

If you're interested in getting a grounding in Ruby, this book still feels like a solid introduction. The edition I read is getting a bit long in the tooth now that we're on Ruby 2.1, but the pace of language change has slowed, and most of the book is still applicable. (If you're buying it new, you should, of course, get the later edition.) The table of contents makes it seem like the book is covering the same ground multiple times, but that organizational strategy worked better than I expected. Ruby is not the most organized language in the world, so I still felt a bit overwhelmed with random method names in places, but I never felt lost in the mechanics of the language.

In short, recommended if you want a good introduction to the language, although probably in a later edition.

Rating: 8 out of 10

Reviewed: 2015-01-03