The Lua programming Language has been around for a while but this book by Roberto Ierusalimschy will be a mark in its history. The book managed to surpass every expectation I had for it, and I was eager! From someone with no Lua knowledge to those with Lua klocs in their backs, this book will be a great companion in a nice to read trip down the Lua 5.0 lane.
The book begins with the basic Lua elements and structures and then advances through control structures, functions, iterators and coroutines. Iterators and coroutines are one of those language features that may confuse the first timers, but the author manages to show the concepts and inter relations between them in a way that clarified the issues even for a seasoned Lua programmer. Alas, make no mistake, the whole first part is totally worthwhile for non beginners.
The second part of the book shows one of Lua biggest assets: tables and metatables. I've seen people sneer at Lua at first glance and then convert themselves to Lua evangelists simply for the features of tables and metatables. The author does his magic and makes a whole set of apparently complex concepts flow by the reader as fluid and logical as they can be.
By the way, fluency is arguably one of the major benefits of this book. The reader is taken from substrate to substrate of the Lua way of life without even taking notice. Every end of chapter left me with the satisfaction of having been presented with one more facet of Lua and with the tranquility that everything was falling in place at the right timing.
After tables and metatables, the book presents the concepts of Packages and Object Orientation in Lua. If you had any doubt ever that Lua was able to sustain "real" Modular/OO programming, be prepared to replace your dogmas. The book not only clarifies how to do it in Lua but also shows how easy and clear the coding gets.
The author ends the second part of the book with a great chapter on Weak Tables. I have to admit that I was somewhat refractory to Weak Tables before I read this book, but after this single chapter I was converted. May the name "weak" not influence your judgment on those Weak Tables. They are great, and the book showed more about them than I was expecting.
The third part of the book focuses on the standard libraries. Those would be the Table, String, I/O, Operating System and Debug libraries. Instead of repeating the contents of the Lua reference manual, the author manages to show lots of new information about the libraries by the use of examples and clear explanations. There are some points in Lua that can indeed be quite idiosyncratic at a glance, but this book is more than enough to clarify every one of them.
The fourth and last part of the book brings us the Lua C API. For the beginner Lua programmer this part will probably be skipped, but for the average programmer and most of all for the hardcore Lua explorer, this part will be pure delight. C programming is not for the faint of heart, but having a Lua interface for your C library is akin to the jackpot of embedded languages in my opinion.
This part of the book shows that the task of wrapping C code for Lua is not only feasible, but easily done once you grasp the fundamentals. Have one thing in mind, this was no small task for the author. Describing such an plethora of resources and how to use them in six chapters demands a clear yet straight to the point approach, and once again the book shines through.
Step by step the author shows how to deal with the Stack, to get arguments from and return values back to Lua, to handle tables (even those big ones), to call Lua functions from C code, to call C functions from Lua code, to handle strings, to handle state (using the registry, references and upvalues), and last but not least to use userdata types and metatables in C.
The last chapter of the book brings two examples of the use of the C API, one offers a directory iterator and the other a really nice example of binding an existent library (expat) for Lua use. Lots of my questions on the C API were dismissed with those two examples.
I should also reserve a praise for the book index. Not only I've found it complete but it is easy to understand some details of the Lua structure only by glancing at the index pages.
Conclusion
Being one of the first readers of this book was not only a great honor but also a great surprise. As a Lua old timer, I wasn't expecting to be presented to so many novelties, subtleties and jewels of programming in almost every chapter. Was I wrong...
If you have not seen Lua until now, this book is THE starting point.
If you are acquainted with other versions of Lua but have not studied version 5.0, this book is a great shortcut for your new endeavors.
Finally, if you think Lua is your native language and no book could teach you something worthwhile, think again. I was grateful I didn't skip not even one paragraph.
We've got the language. We've got the book. Let the revolution begin... :o)
