Beginning Lua Programming 173
Simon P. Chappell writes "These days, Brazil is no longer just on the map for its fine coffee and martial arts. They have a few other reasons and one of them is called Lua. Lua is an open-source scripting language that was originally designed for small size and excellent portability to support its use in embedded systems. Like anything good, it didn't take long for it to be discovered by others looking for a small and efficient scripting language."
| Beginning Lua Programming | |
| author | Kurt Jung, Aaron Brown |
| pages | 400 |
| publisher | Wiley |
| rating | 9 |
| reviewer | Simon P. Chappell |
| ISBN | 0470069171 |
| summary | A great introduction to Lua with solid writing and explanations of the concepts |
This is definitely a book targeted at those new to Lua. While it begins gently, it picks up speed quite quickly and takes its reader through a full range of Lua usage. This book is unusual, for the more mass-market beginner books, in that it does not treat the reader like an idiot. I found the tone to be very respectful of the reader's intelligence. This aspect alone, makes the book stand out in a crowded beginners market.
This book is also a very good introduction to Lua for programmers experienced with one or more other programming languages. I found it very easy to pick up the concepts with my previous programming experience.
The first chapter of most books like this, will typically cover getting setup with the language. This book delivers well, with not only explaining how to install the binary version, but also covers compilation under Unix-styled operating systems and a number of development environments for Microsoft Windows. Guidelines are given for building Lua on Windows using Visual C++, Tiny C and MinGW.
Chapter two is called "First Steps" and is a walkthrough of all of the core language. This is well done and there are plenty of examples where a Lua command is typed and the resulting display from the Lua environment is shown. Chapter three is dedicated to the art of the Lua function. Functions are first class values and have enough power and complexity that they deserve their own chapter. Did you know that Lua automatically recognises tail recursion and handles it appropriately? It does. So if your looking to experiment with some of the trendy functional techniques that tend to swamp Reddit these days, Lua would be a good place to try it.
Chapter four explores Lua's only data structure, the table. What's a table, you ask? My best description, as far as I've managed to get my head around it, would be that it's a Swiss-Army Knife style Hash Table with multiple personalities, alternatively thinking that it's an array, a list, an Erlang-style tuple or a tree structure. However you decide to use it, this chapter explains it and provides lots of examples. Chapter five brings us that ultimate datatype, the string. As with tables, Lua can do many things with the humble string and this chapter will make sure that you can work with substrings, handle user input, read and write files and use the built-in pattern matching available in the language.
Chapter six covers "Handling and Avoiding Errors". I know, I know, we don't have errors anymore, now that we've all discovered the benefits of agile development using scripting languages. Except that we do and circumstances external to our programs can still bring pain to our code. Users type the wrong things, network connections die, power can go out suddenly and, of course, sometimes there are parts of our programs that aren't as imperfect as we'd like to think they are. Chapter seven is about "Using Modules" and explains Lua's interfaces and implementations together with guidelines on modularising scripts and calling those modules.
Any agile language worth its electrons is going to have meta-programming facilities within it. Lua has them and chapter eight is where we learn about "Extending Lua's Behaviour with Metamethods". Chapter nine examines Lua's ability to handle events using coroutines. This is a powerful feature and enables Lua applications to manage concurrent tasks with ease.
Chapter ten explores the fascinating world of Lua internals. While Lua is a scripting language, it does use a virtual machine, this chapter shows how scripts can be pre-compiled to the appropriate bytecode. It also covers memory management and implementation details for tables and strings. Chapter eleven is somewhat reference-like, covering the standard libraries supplied with Lua. Chapter twelve is a good compliment, describing some of the available libraries from the Lua community.
Chapter thirteen addresses the matter of interfacing Lua with other languages. If your language can handle C-style calling conventions, then it can be used by your Lua programs. Chapter fourteen is for everyone that wishes to store information in a database now and then. Lua has bindings for connecting to a number of popular database systems and this chapter will help you use them.
My favourite chapter is number fifteen, where using Lua for web applications is explained. There are several alternatives for the budding Lua web application programmer, ranging from that humble and faithful technique, the CGI script, to the Kepler web server environment with the convenience of LuaPages. In this highly-connected world, it is important to be able to communicate over a network and if chapter fifteen didn't tip you off, then chapter sixteen will make you absolutely certain that Lua is ready for networks. Chapter sixteen explores networking from LuaSockets to email and webpages.
Lua is very popular among video games designers. While not generally used to write the frameworks, it is often used for in-game scripting. Chapter seventeen recounts many of the ways that Lua can be used within video games. Chapter eighteen will appeal to the Palm carrying geeks in the house. If you've been looking for a programming language for your Palm PDA, then Plua may be just what you were looking for. Plua (actually Plua2, but they call it Plua) is an implementation of Lua 5.0 for the Palm OS. It gives full access to both data and graphics and is programmable on the Palm; no need to be tethered. Finally, chapter nineteen addresses the subject of "Fitting into the Lua Community".
That's a long list of chapters. Phew! After all of that, let's see what was worth noting along the way.
The writing style is good. Light without being flippant and respectful of the readers intelligence. I like that. I liked the fact that the topics were broken down into appropriately sized chapters. It meant that this book has more chapters than usual, but each one is nicely partitioned, so it doesn't feel over-whelming. I also like the fact that this book seems like it will continue to be useful in the medium term as well. Some beginners books stop being useful quite quickly after you've learned the basics from them, but this one covers quite a number of topics that will useful at the mid-level of Lua skills.
I have very little negative to say about the book. While I normally don't care for books much larger than 300 pages, this one doesn't feel like it has any gratuitous stuffing in it. There is an appendix with answers to the programming questions asked here and there in the chapters, but other than that, everything feels like it should be there.
As a typography and layout nut, I did feel that the layout was a little cramped and the primary type size was a little small. The program listings were generally well done, although I'm not sure that every single one needed a gray background to help separate it from the body text.
The title of chapter nineteen, "Fitting into the Lua Community" seemed a little patronizing to me. I understand the need for maintaining community values, but most communities do that fairly well without the aid of authors playing the heavy. Apparently the community lasted this long without the book. Let's hope they make it a little longer, now that the masses know about it.
All in all, this is a great introduction to Lua. It has solid writing and explanations of the concepts, with plenty of examples. Recommended.
You can purchase Beginning Lua Programming from amazon.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
LUA in WoW (Score:5, Informative)
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I've looked at it and it looks like it'd be something really nice to incorporate into projects where you'd like to give people scripting abilities, but it's got some really really annoying things:
It looks like a cross between Pascal and BASIC
OK, well, that's all I could think of.
It almost makes my head hurt.
I suppose if I had been doing VB over the past decade instead of using all C-like languages, I could wrap my head ar
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As for Lua, it's neither BASIC nor Pascal syntax-like. Syntactically it's probably closest to Modula without semicolons (which is a good thing, very clean syntax), or Ruby for something more modern to compare to. Semantically it's somewhere between Scheme and JavaScript.
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You can easily hook up a Lua method to access a variable in your containing applicat
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Other games too (Score:2)
Yeah... (Score:3, Funny)
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That struck me as odd, too. A joke? I always thought Brazil was on the map for the Amazon, Carnaval, and fine women (see: Carnaval). I suppose you can also add ethanol and insane gang and prison violence.
Insane gang and prision violence?? (Score:1, Insightful)
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You forgot hacking.
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>I pretty much stopped reading after that.
Exactly. If theres one thing I cant s'tand its people who dont know how to us'e punctuation.
Re:Yeah... (Score:5, Funny)
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WoW (Score:2, Informative)
LUA in games (Score:2, Informative)
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As another example of what you can do with Lua, it is used in Ion, a window manager (http://modeemi.fi/~tuomov/ion/ [modeemi.fi]). Granted, it is a little known window manager, intended for people who dislike mouse and fancy graphic effects, but it has been designed to be a lightweight solution and that's why Lua had been chosen.
http://www.yzis.org/ [yzis.org] uses it also.
Another scripting language? (Score:2)
Re:Another scripting language? (Score:4, Informative)
I must agree though that this article didn't do too much in terms of selling the language, which is probably what the book is supposed to do.
Re:Another scripting language? (Score:5, Insightful)
Lua is useful because it's easy to fold into other programs. Lua is what you pull out when you're writing an application in a non-scripting language but you decide to make part of it user-scriptable. Conversely, you may be using one of those applications, in which case there are Lua scripts around for you to play with.
Some examples of what it's good for (Score:4, Informative)
It's also extremely small in terms of memory size and footprint, making it ideal for some embedded applications. I've used it to create a (yes, really) AJAX-enabled web-UI for configuring small Linux boards.
I had to write some sqlite bindings for Lua to do it (sorry, closed source, GRRR) but it really wasn't even remotely hard.
On the downside, most Lua projects start to feel like Lisp as you start to add your own language support for things that aren't in the core, and it's best to avoid the object/module support -- that's rather hairy stuff.
Non-OO (Score:2)
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when they say "lightweight"... they mean it (Score:5, Informative)
Should you use it for your online web application backend, or your system administration scripts? Probably not.
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Did you just get modded up for not being able to type "MIT license" into google?
MIT is BSD-style without any clause that would stop it from being re-used in a commercial product. And sorry guys, this is a requirement for use in games right now.
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Does it matter?
Here, let me fix this for you:
If the game had been written in Perl/Python/Ruby in the first place, no additional scripting language would be needed. Granted, Python is probably the only one of those that's reasonably fast enough, but still...
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I'm not convinced of that. Until very recently (until people started actually thinking about 64-bit gaming), Python looked like a very real possibility. Almost fast enough, can be extended with C (and thus Assembly) for the few cases where it's not, and I believe there are ways to compile it to an EXE.
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No, I'm saying that there are reasons, but they don't often apply when people think they do. We could start by you telling me which reasons you endorse for using another language...
(And no, I'm not a drooling Python fanboy. In fact, I hate Python. Perl6 looks better, but there are things I hate about it, too, and it's not even out yet. I just am not en
So how do you pick a language? (Score:2)
Other than that, how do you pick a language? Do you just go for whatever was popular in school?
As usual, if you want lightweight and featureful.. (Score:3, Interesting)
No, but SIOD [delphiforums.com] fits into 75K, has a track record with the Gimp and game extension, and has a use-it-any-way-you-want license. I've used it for web-related stuff and sysadminish things, too.
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A potential competitor here is Tcl, which, like Lua, has an embedding background.
You can't fit Tcl into that space either these days. But you do get more functionality out of the box, and it's trivial to profile that functionality for specific application usage too (very useful for embedded use).
Tcl uses the
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It is extremely easy to embed. (Score:5, Insightful)
I don't know that I would go out of my way to learning it just to learn it, but I would love to see it become the defacto scripting language for linux desktop apps.
YAML versus XML or JSON (Score:2)
Indeed there are extremely few XML applications I have seen that would not be much better served by YAML. for example,
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You put that in parentheses as a secondary characteristic, but that's the very distinguishing reason why XML was invented. You're not supposed to need complete documentation for using a XML file format, they should mostly self-documenting - it was designed as a flexible format for interchange. Binary and XML are for different goals, you preferring one over the other is like saying that you prefer cars over railways because
Lua works on Lego robots (Score:3, Informative)
Java does too http://lejos.sourceforge.net/ [sourceforge.net]
I don't think there are python or ruby ports though, possibly because these devices are very limited.
It's an embedded data-description language (Score:2)
1) It's designed to be embedded in applications.
2) It's a data-management language.
Other languages can be embedded, but it's harder to do (at least when I last looked), and I have yet to see an embedded language as lightweight as Lua with equivalent features. It also has the advantage of being a self-describing human-readable data format (plain-text), but it has an advantage that it's ALSO a language. While all la
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That makes it a pretty poor choice to do anything that's fairly complex, because under the covers you're still going to write a significant amount of C. All the flexibility of a scripting language, all the danger of C code is not a place I like to spend my time.
Lua is a tiny, tiny scripting language, which is pretty cool. However, it also has an e
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When it comes to day to day scripting, I don't think its worth to learn, since it just doesn't provide much in that area, its just not what is was build for. What LUA however is very good at is getting embedded in other applications, in that area it just is way superior to perl/python/ruby/etc.
Its not just a matter of size, but mainly a matter of flexibility, i.e. if you
Try out lua - on Nmap (Score:4, Informative)
With lua and NSE, nmap can now do things like vulnerability testing. Why not download nmap [insecure.org] now and give it a try?
Supreme Commander (Score:3, Informative)
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The entire user interface is scripted in lua, which facilitates a huge array of user made customizations.
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Small? (Score:3, Insightful)
Small and efficient? Sure, for now. But wait until the rest of the OSS community gets done with it. I give it two years tops before, like PHP, it's been "extended" with 1.67 million indecipherable functions.
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Explanation of "Fitting into the Lua Community" (Score:2, Insightful)
No, that won't happen. To understand why, you first have to understand what the reviewer meant by "Fitting into the Lua Community". This was a mighty unusual chapter to find in a book, and many will have wondered what was behind it. Well, there is no substitute for experiencing it yourself directly, but here's a small explanation by way of preview.
The Lua community is odd, very odd. It contains ma
Is it only for extending things? (Score:2)
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I find that when I'm writing stuff in ruby, I enjoy it a tad more, than say, perl or php. I've not measured it but I think there is a correlation between enjoyment and efficency. Maybe only in that I get sick of the project I'm working on at a later
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Can't say about all of them, but most of them only allow you a single VM, which just isn't good enough when you want to keep your scripts apart from each other and secure (i.e. in a game a users script shouldn't crash the engine or change the behavior of other unrelated scripts). In Lua on the other side you can have as many VMs as you want and you never run the risk that any scripts breaks out of its little sandbox. You might be able to repl
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Let's say your're working on the PSP. You've got 24MB to start with. Take away 4MB for the executable and static data, 5MB for your core geometry & textures (player, car, whatever.) 2MB for sound, half a meg or so for display lis
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Yes, about zillion od them. My impression is that lua is more powerful than s-lang, easier to learn than scheme, and smaller and more portable than ruby/python/perl.
I'm sure I'm not the only one to point it out, but (Score:3, Informative)
What's with the "base index of 1" array conventions in their standard library?
I love Lua, and have played around with it quite a bit, but that part of their specs always annoyed me. Interestingly, it is flexible enough to allow custom "standard lib" code that uses base index of zero. Also, custom scriptable objects can define their own conventions, including relying more on the iterator interfaces, which forces things to be theoretically cleaner.
But still, just having that even as a possibility irks me.
Re:I'm sure I'm not the only one to point it out, (Score:4, Informative)
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If your natural numbers start with 0, then the Ordinality of n (the position number in the sequence of natural numbers) is equal to the Cardinality of n (the amount of numbers, that are smaller than n).
So whenever you have to talk about both position in (ordered) sets and size of sets, starting to count with 0 has its advantages.
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There are a few replies to your post about merits of a base index of zero. But I wanted to elaborate on the collections framework thing.
Lua, being a new language, should have right away very heavily discouraged the use of anything but abstracted opaque collection types such as unordered sets and collections and iterators. Sure, those seem a little clunky and slow compared to the iconic for(int i = 0; i < n; i++) but they actually allow for faster and more streamlined implementations when the traditiona
And it won't take too long (Score:2)
Why bother? (Score:2)
Cue the toilet humor (Score:3, Insightful)
I guess all the Americans here didn't get it.
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Step up to Lua (Score:1, Insightful)
Although there is good progress with the Kepler project, there is not
Some thoughts on Lua (Score:2, Informative)
I got on the Lua bandwagon last year, and for what it is designed to do, it is quite good.
Before I start cheerleading, some comments on the book. Beginning Lua Programming (BLP) is a very good book on the subject, especially for people new to Lua or perhaps even to programming. I own this book as well as the "Programming in Lua" (PIL) book by Roberto Ierusalimschy, the latter of which I think has some of the best technical writing I've seen in a computer book and is on par with the likes of the late W. Ri
Too heavy... (Score:2)
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The Important Question is (Score:2)
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A stripped-down Scheme which offered a one-shot alternative to Scheme continuations, more like Lua's coroutines, might help. To compete with Lua, it would also need to be implemented as a bytecode interpreter. Existing Schemes like MzScheme and Guile are relatively heavyweight. TinyScheme isn't bytecode-based
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with (an, addition, operator)
Chosen for pdftex successor (Score:2)
http://www.luatex.org/ [luatex.org]
Makes easy a lot of things which had required some bizarre texniques.
William
rebol pros and cons and Lua (Score:2)
Fine coffee and martial arts? (Score:3, Funny)
Geeks. Geez.
Football, samba, carnival? (Score:2)
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Yeah, you forgot the women.
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Re:The ignorant and SlashDot authorship... (Score:5, Insightful)
Mardi Gras?
There is no such thing in Brasil. I guess you mean carnival [wikipedia.org], it differs from mardi-gras in the ammount of naked people (and crossdressers).
Nazi hideout?
I think you confused Brazil with Argentina [wikipedia.org]. A lot of criminals flees to Brasil, a lot are born there, but Nazi is not really our specialty, as our ethnic diversity would easily get them mad and bust their covers.
Soccer?
We don't know this sport there. But we are five times champions of Football (Association), if that is what you mean. (Tongue in cheek)
Regardless of that, I agree with your take, Brasil is not known only by its fine coffee and Martial Arts. It is not even known by it's Martial Arts, for god sake, except for people that follows MMA and know that Brazilian Jiu Jitsu exists (we in Brazil don't call it that, we call it only Jiu Jitsu).
The general sensation in Brazil is that we are known by our futebol, our samba and carnival, our giant man-eater screaming snake overlords (anacondas), our monkeys and our natural beauties (landscapes and women).
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Doesn't that make them cross-undressers?
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Obligatory Simpsons' quote:
Homer: I have a bladder the size of a Brazil nut.
Taxi Driver: We just call them nuts here.
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When I read the intro I first thought of Capoeira. Is it part of the culture in Brazil, or just well advertised here in the States?
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I might be missing something, but I've yet to see the name "Embraer" [embraer.com] in any of these threads.
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(yes, this is an Americentric post)
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Aircraft? (Score:3, Informative)
One should add to that that Brazil has one of the largest aircraft manufacturers in the world [embraer.com]. Embraer started in 1969 as a federal government owned company and was privatized in 1994. Although they had some technology transfer contracts with foreign companies in the past, their current lineup of airplanes [embraer.com] has been totally developed in Brazil.
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