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Programming in Lua 2nd Edition 131

Andre Carregal writes "In the second edition of Programming in Lua Roberto Ierusalimschy presents the Lua programming Language in a simple yet precise format for both novice and advanced programmers." Read the rest of Andre's review.
Programming in Lua, 2nd Edition
author Roberto Ierusalimschy
pages 328
publisher Lua.Org; 2nd edition (March 5, 2006)
rating 10
reviewer Andre Carregal
ISBN 8590379825
summary Shows how Lua is the language of choice for anyone who needs a scripting language that is simple, efficient, extensible, portable, and free.


The Lua programming language has been around for more than 10 years, but only recently has it started to appear on the mainstream radar screens. It has evolved from a simple scripting language to a full-fledged solution for scripting and embedding. Lua is portable, fast and small, and the language of choice for applications as diverse as games, Web sites and robot controllers as the Lua Users Wiki and LuaForge will confirm.

Lua portability can be shown by the long list of operating systems it runs on, which includes not only Windows and Linux, but also small systems and mobile devices. The memory and CPU requirements for the runtime are really low, and Lua has been used in environments that most other scripting options would not dare go into.

One of the milestones of the history of Lua has been the release of the book Programming in Lua (a.k.a "PiL"), by Roberto Ierusalimschy, in 2003. This review is about the second edition of Programming in Lua, a.k.a. the "Blue PiL" due to the color of its cover.

Lua is free software and can be obtained from its site (www.lua.org). There you will also find the reference manual of the language and the full contents of the first edition of Programming in Lua.

As a disclaimer, let me say that I'm one of the technical reviewers of the book and I have been working with Lua since 1993, most of the time interacting with Roberto Ierusalimschy, even when not working in the same projects as him.

The second edition manages to surpass an already good book in various aspects. The "Blue PiL" presents not only the language itself, but also gives an excellent view of how one could see Lua as the foundation of solid scripting techniques. The original Programming in Lua was focused on Lua 5.0, while the second edition focuses on Lua 5.1. While the differences between Lua 5.0 and 5.1 are not radical, the newer version has a lot more to offer, both in terms of the modularity aspect and of language features. The second edition of Programming in Lua indicates clearly when some concept or detail relates only to a specific version of Lua, but most of the contents can be applied to both Lua versions.

Programming in Lua is oriented to both the novice programmer who wants to get a first feeling for Lua, and to the advanced Lua or C programmer who wants to use the full potential of the language. The book clearly separates the two aspects and indicates the sections that can be skipped for each reader profile. The author manages to keep a light and easily readable style during the whole book and the examples are simple and direct, making the flow of the reading quite pleasant. I can say that, even having some reasonable experience with Lua, I was surprised by a lot of details in the book. The "Blue PiL" is one of those books that you can read many times over, and each time you learn something new.

The "Blue PiL" starts with an overview of the Lua language and slowly evolves through the more advanced concepts and the features that make Lua such a unique language. Even though it's a relatively thin book, it goes from the starting concepts to the more sophisticated ones with a grace that is really rare to find. The one other book that comes to mind with an effect like this is the classical Structure and Interpretation of Computer Programs by Harold Abelson and Gerald Jay Sussman, which says a lot.

The first part of the book presents the language and the basic features. In particular, concepts such as iterators, coroutines and closures are presented in a clear way, which is no small feat considering that many readers will be having contact with such concepts for the first time.

One of the strong points of Lua is its simplicity, but don't assume that this implies lack of power. An example of this balance is the table data structure, in fact the only data structure for Lua. Tables allow the construction of every other data structure (arrays, sets, bags etc) but also allows the use of sophisticated techniques such as metamethods, function environments, modules and object orientation.

In fact, instead of providing every feature one might want to use, Lua provides the meta mechanisms so you can create your own features, or use them as modules created by third parties. In order to explain the full power of these meta mechanisms the second part of the book takes the reader from the basic steps of creating a table and shows how each of the mechanisms can add features or help the usage of some advanced concepts.

As an example, the chapter on object-oriented programming not only shows how to use objects in Lua, but also how to think of objects as prototypes for other objects, and how to implement inheritance on such a model without using anything too fancy.

There are also chapters on the use of metatables (basically tables that define the behavior of other tables), the use of tables as function environments (a really powerful mechanism once understood), modules and finally weak tables. Weak tables allow the advanced use of memory resources in an automatic way, providing mechanisms for data structures that tend to be hard to implement in other languages, if even possible at all.

This slow but efficient presentation of concepts that, though complex, can be easily assimilated by the reader is a predominant aspect of Roberto's work. He is not only a skilled author but also knows how to present things in a way that a novice can grasp and an expert can master.

The third part of Programming in Lua covers all the language libraries (math, table, string, system, debug and I/O) in clear prose and shows that even with a small set of libraries Lua can pack a lot of power on a very small footprint.

Finally, the last part of the book is directed to programmers that want to use Lua to its full potential. Lua can be used as an extension language or as an embedded language, and knowing how to interact with the host language (C, C++, Java, Delphi etc.) is mandatory for that. The book presents the C API for Lua in the same progressive pace, but also manages to cover every ground needed so one can add Lua to a project without much pain, if any.

One important thing to note about the book is that it follows the same philosophy that guides the language, showing that simplicity and lightness has nothing to do with lack of power or coverage.

I really recommend this book to anyone interested in learning Lua, and also for those who already know how to use Lua but would like to fully master its way of thinking, the so called "Lua way" of doing things. The book has been considered by many as an excellent guide on programming, even if one is not interested in Lua in particular."


You can purchase Programming in Lua, 2nd Edition from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
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Programming in Lua 2nd Edition

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  • by Anonymous Coward
    > "Roberto Ierusalimschy presents the Lua programming Language in a simple yet precise format for both novice and advanced programmers."

    Of course, if you grew up with a last name like "Ierusalimschy", reading Perl aloud is probably pretty old hat for you. For that matter, so are APL and Brainf*ck.

    • by k4_pacific ( 736911 ) <k4_pacific AT yahoo DOT com> on Wednesday October 25, 2006 @02:33PM (#16583194) Homepage Journal
      Yeah, no kidding, Ierusalimschy isn't a name, it's a bad Scrabble hand.
      • by hesiod ( 111176 )
        > Ierusalimschy isn't a name, it's a bad Scrabble hand.

        Actually, to get that you would have to be cheating... badly.
      • One of the best MST3K lines (and one of the most useful in real life) ever!
      • We are not amused. The name looks like it's related to Jerusalem, it just looks a little odd in English due to the particular transliteration (cf. Iesus, Iehova). There are countless other examples of family names based on cities, this is pretty much like "von Jerusalem".
        • Re: (Score:2, Insightful)

          by Raenex ( 947668 )
          Who's "we", and when did they elect you to speak for them?
          • "We are not amused" is just a Monty Python way of saying "this is not funny". It was used in a sketch of Queen Victoria, who presumably referred to herself in plural. If you didn't recognize the line, please hand in your geek card on the way out ;)

            However, I also have a (Finnish) name that's pretty incomprehensible to English speakers, so I feel qualified to note when people make fun of something on the basis that they don't understand it.

            • by Raenex ( 947668 )

              Ah. I'm one of those anti-geek-establishment geeks who isn't into Monty Python. But besides that, I think you're being overly sensitive. The guy's last name looks funny to the average Slashdot reader. So what? I didn't detect any viciousness in the jokes.

      • You cheat, Dr. Jones!
  • Perfect... (Score:2, Informative)

    by T.Louis ( 1015101 )
    ... for the Burning Crusade expansion of World of Warcraft (Lua 5.1) and customized UIs!
    • Re:Perfect... (Score:5, Interesting)

      by jdray ( 645332 ) on Wednesday October 25, 2006 @02:42PM (#16583332) Homepage Journal

      I really recommend this book to anyone interested in learning Lua, and also for those who already know how to use Lua but would like to fully master its way of thinking, the so called "Lua way" of doing things.

      Every time I see one of these "Learn Language X in Your Spare Time" book reviews, I wonder, "Why another language?" Advancement of languages is good, and "new" languages like Ruby are great, but how many programming languages are we as a community going to produce? Like text editors, it would be better to focus on fewer targets and add features than keep coming up with new "my toolbox grew so big I created a compiler for it" languages.

      Of course, I may just be trollish today. Hard to tell.

      • Re: (Score:2, Interesting)

        Every time I see one of these "Learn Language X in Your Spare Time" book reviews, I wonder, "Why another language?" Advancement of languages is good, and "new" languages like Ruby are great, but how many programming languages are we as a community going to produce? Like text editors, it would be better to focus on fewer targets and add features than keep coming up with new "my toolbox grew so big I created a compiler for it" languages.

        I think that what you say really does apply to a number of languages

      • by misleb ( 129952 )

        Every time I see one of these "Learn Language X in Your Spare Time" book reviews, I wonder, "Why another language?" Advancement of languages is good, and "new" languages like Ruby are great, but how many programming languages are we as a community going to produce? Like text editors, it would be better to focus on fewer targets and add features than keep coming up with new "my toolbox grew so big I created a compiler for it" languages.

        "Because different people prefer different text editors" would be the o

      • The 'neat' thing about this language seems to be its easy memoization of functions. That would make it a good choice for programs that do certain kinds of calculations (and by the look of it, calculations that tend to be used in games). [wikipedia.org]

        Any of these 'new language X' are written to tackle a particular problem set. Would you use perl or C do to string munging? Would you use perl or Fortran to do fast and heavy number crunching? Being aware of what languages are out there may save you time when you encounter a
        • by radtea ( 464814 ) on Wednesday October 25, 2006 @05:19PM (#16585558)
          Would you use perl or Fortran to do fast and heavy number crunching?

          Incredibly, there is a rather good 4th order Runge-Kutta ODE solver available in Perl. I used it once because I wanted something quick and dirty, and expected performance would be terrible, but when I later translated it into C++ I had to squeeze pretty hard to get more than a factor of two speed increase. And the difference between C++ and FORTRAN is less than a factor of two for most applications these days (although I do confess to missing FORTRAN's optimized exponentiation.)

          Furthermore, with decent regex and string classes available for every language under the sun (except FORTRAN, of course...) there is less and less reason to prefer one language over another, and even less reason for people to go mad and write their own. And if you really need the performance of LAPACK in FORTRAN then you can call into it from C++ easily enough.

          If one is writing applications, then it is very hard to beat C++, especially given the number of excellent cross-platform application frameworks (I'm currently very happy with wxWidgets, but have used Qt heavily in the past). For scripting one has a wide range of viable choices: perl, python, Java... These are all well-supported, have large user bases, and while they are unsuitable for serious application development for a number of reasons, they all do the sorts of things we want scripting languages to do: runtime optimization, garbage collection (admittedly broken in many JVMs, but working well in perl and python), and adequate cross-platform support.

          So in this environment, new languages are more of an irritant than anything else, perhaps useful for their experimental value, but if you really want new features in perl or whatever, then the best way to get them there is to work on the development of that language, not re-capitulate everything with an almost-completely-but-not-quite-identically similar syntax. Given that perl 6 is near-as-damnit a new language anyway, this is a particularly auspicious time for such endeavours.
          • Re: (Score:3, Insightful)

            by Bastian ( 66383 )
            I hate to burst your bubble, but if C++, Perl, Python, and Java are really such solid languages that there's no reason why any programmer would want anything else, then the world is screwed. Furthermore, adding new features to existing languages really isn't the solution - that path leads to madness, to kitchen-sink monstrosities like C++ and Perl. Both of them have traveled so far beyond the pale that their creators have admitted the desire to more or less start over and make a cleaner language that does
            • by radtea ( 464814 )

              Embedded languages certainly have their place--I've used perl as an embedded language in the past and am likely to use python in the future. But using rare languages is problematic--it requires that whoever maintains your code in future is familiar with the same languages you are, and it requires that debuggers support calls across rare language boundaries.

              And while large languages do get bloated, they also get refactored, and from a community perspective we are far better off with people putting time into
              • by Bastian ( 66383 )
                I agree that using rare languages is problematic, but it's not showstopping, and it's not an argument for not using them - after all, if using them were always a bad idea, we'd still all be stuck with nothing more than a few languages like FORTRAN and BCPL.

                I question the idea that programmers not knowing the language is much of an issue - for the most part, all languages use variations of the same C-like syntax with only a few break-aways such as Smalltalk, Lisp, or FORTH. Besides, there are plenty of prog
            • I just cringed when you were grouping Perl with Java there... For that matter, I'd cringe if anyone would group any language with Java. It's really hard to make comparisons when you know that Java is pretty much always the worst choice in efficiency, speed and transparacy.

              But oh well :(

              Splut.
              • by Bastian ( 66383 )

                I just cringed when you were grouping Perl with Java there... For that matter, I'd cringe if anyone would group any language with Java. It's really hard to make comparisons when you know that Java is pretty much always the worst choice in efficiency, speed and transparacy.

                I have a feeling you're spouting cool-kid party line more than anything. Yeah, Perl has Java on memory consumption. But Java beats Perl [debian.org] hands down on speed. As for transparency, well, I guess there's no accounting for taste, but I think

          • (I'm currently very happy with wxWidgets, but have used Qt heavily in the past).

            Have you looked into FLTK? I confess I haven't looked at wxWidgets lately, but when I had to choose a free, cross-platform widget library a couple years ago, I decided FLTK was my best choice. I was a bit put off by its sluggish development, but I liked the API.
            • by radtea ( 464814 )
              Have you looked into FLTK?

              I looked at it many years ago, but it was just Not There in terms of the functionality I wanted. wxWidgets (wxWindows, in those days) wasn't ready for prime time either, which is why I went with Qt. I'm happy with wxWidgets as it stands today, and have enough invested in it to not want to change again.

          • If one is writing applications, then it is very hard to beat C++, especially given the number of excellent cross-platform application frameworks

            Just like junk food is the most popular food in the US, junk programming languages are the most popular languages: cheap, widely available, and many people are "happy" with them. They also cause analogous problems: software obesity and software heart attacks.

            Basically, your entire rant is just reiterating standard stereotypes about languages and just shows that you
      • by flynt ( 248848 )
        If we use your technique, I don't think we'd have Ruby for instance. There are far too many different kinds of people and programming tasks and techniques to limit to a few. If no one uses a new language, it dies. I don't see the problem here, it seems we're better off having too many options than too few!
      • Re:Perfect... (Score:5, Insightful)

        by alienmole ( 15522 ) on Wednesday October 25, 2006 @04:08PM (#16584674)
        Like text editors, it would be better to focus on fewer targets and add features

        The history of programming languages shows that this is a good way to kill a language. Languages are a delicate balance between enabling you to express things, and preventing you from expressing things. You can't just throw the kitchen sink in there and expect the result to be usable. People design new programming languages because they perceive limitations in the ones they already know, limitations that often can't just be overcome by adding features.

        From a programmer's point of view, a good reason to learn a new language is to expand your mental horizons. It can be a passable substitute for actually studying computer science (which you clearly haven't done, if you're asking "why another language?") Don't just learn an array of similar languages, like Python and Ruby. If you already know a popular OO language, then learn a language like Scheme, ML, or Erlang, or if you really want some nerdy metaphorical hair on your chest, learn Haskell (although you might want to start with one of the others first). Then you'll understand "why another language".

        • You've made the argument for learning another category of languages, not another language. Unless Lua is such a paradigm shift that it warrants its own, new category, then the GP's question remains a good one: Why another language?

          I was thinking "why another scripting language", but I don't know bupkis about Lua. But the problem is one can only be truly fluent in a couple or four languages, at a time. Outside the few that I have the chance to maintain high levels of expertise in, code that I write in any ot
          • I answered the original question in a general way, because it was stated generally, i.e. "Why another language". In Lua's case specifically, it has borrowed important features from Scheme and Icon, so for those who insist on only learning popular languages with familiar syntaxes, it might be a way to gain familiarity with some interesting capabilities that you won't find in standard Python, Ruby, or Java.

            But I don't think anyone is arguing that you should learn Lua specifically just because it's there. Yo
            • by jdray ( 645332 )

              You might learn Lua if you're looking for a lightweight embeddable scripting language, in which case it's one of the better choices available; or if you're working with one of the systems in which it's already embedded, in which case Lua is a foregone conclusion.

              Okay, so you have me interested. Can you elaborate on just what an "embeddable scripting language" is? I mean, I have an idea, but go about it as if I have no clue. That will satisfy those that believe such.

              And, just to let you know, I feel l

              • Okay, so you have me interested. Can you elaborate on just what an "embeddable scripting language" is? I mean, I have an idea, but go about it as if I have no clue.

                It's a language that can be integrated into an application at the source code level, so that the language becomes part of the application and has access to all that application's internal structures. This allows you to easily write programs which control (or "script") the application. This is one of the most successful software development

          • I agree that most people are not capable of maintaing fluency in more than a couple languages, but nobody's making you learn this new fangled language and neglect another. Lua, Python, Haskell, and all the rest exist because they encapsulate something new, that goes beyond syntax. The ideas might turn out to be really dumb, or it might turn out to be very smart, and then we all run of and try these things in our favorite language.

            I hated the whitespace thing in Python, now I'm convinced that every language

      • Re:Perfect... (Score:5, Insightful)

        by Cthefuture ( 665326 ) on Wednesday October 25, 2006 @04:34PM (#16585018)
        For starters Lua is older than Ruby so be sure to point your finger in the right direction. Lua was already at 1.0 when Matz starting thinking about Ruby.

        But Lua is different than those other languages anyway. It's extremely small, both as a language and as a binary. It's also easy to embed anywhere you need it. And finally it's pretty fast as far as dynamic languages go.

        Lua doesn't get enough credit these days. It's used in tons of products (especially games) but most of the time people don't realize they are using it.
        • Re: (Score:2, Interesting)

          by jdray ( 645332 )
          I have to admit that I don't know from shineola a thing about Lua. The book review didn't do anything to compel me to find out more, though, and that's unfortunate if Lua is such a wonderful thing to behold. It's not necessarily the job of a writer of a book review to educate his readership about the subject of the book in question, but a short paragraph telling me in a few sentences why I should care about Lua might make me more susceptible to his argument that it's something I should rush right out and
      • by crucini ( 98210 )
        I think Lua's main selling point is ease of embedding. When you write a large C++ application, you frequently end up wanting some embedded scripting language.
        Some interpreters, like Perl, are tricky to embed. Lua is very friendly to embedding. You can call user-defined Lua functions from C and call C functions from Lua.

        The interpreter is small, and the language is sandboxable - for instance, you could have untrusted Lua running in your webserver and it would have no access to I/O or filesystem.
    • Lua has the same relationship with WoW Lua that Java has to Javascript. One is a powerful, flexible, modular language and the other is a braindead scripting language that happens to share keywords and syntax. I understand that Blizzard wants to keep security within the game solid, but it was a real exercise in frustration to learn what little can be done within the game's engine. You want to customize the UI? Fine. You want to do some interesting things with chat text? Go ahead. You want to step outs
      • Yes, you are right it is restricted. But it is a game, it is not about who can write a macro/bot with a nice UI controller to play the game for you right? And besides, if you think it is that limited, go and download some of the more popular UIs and look at the creativity that flows from being constrained by such crap. My initial comment was sarcasm, maybe it was misunderstood, maybe not. T
      • by Res3000 ( 890937 )
        But that's exactly the thing LUA in WoW should do. Change your UI, and change things in your chat. You aren't even allowed to do other things than that. And I honestly don't know what else I would do with it. I don't want it to play the game for me.
  • ref book online (Score:5, Informative)

    by Anonymous Coward on Wednesday October 25, 2006 @02:30PM (#16583134)
    Every page has a donation or Amazon link...
    Anyways the ref book is online:
    http://www.lua.org/manual/5.1/ [lua.org]
  • Moo (Score:3, Interesting)

    by Chacham ( 981 ) on Wednesday October 25, 2006 @02:36PM (#16583228) Homepage Journal
    As a disclaimer, let me say that I'm one of the technical reviewers of the book and I have been working with Lua since 1993, most of the time interacting with Roberto Ierusalimschy, even when not working in the same projects as him.

    Disclaimer or not, should he be allowed as a reviewer?

    Hmm, the Review Guidelines [slashdot.org] state
    Important: If you have a relationship (other than as an ordinary reader) to the author or publisher of a book you're reviewing, disclose that relationship. This means not only cases like "My brother, the author, has given me a million dollars to type this review, and is holding me at gunpoint, while dictating to me from the Amazon review he himself wrote," but also "I used to work at this book's publisher, and was a technical reviewer for this book's three chapters on networking," or "The author is a good friend of mine." Better to disclose more than you think necessary (it can always be edited out if sensible; we'll let you know if we think there's an inappropriate conflict of interest) than less than actually necessary. If in doubt, please speak up.
    So, it OK according to the guidelines. Though, i'd wonder if someone so involved is a good person to actually write such a review.

    • Disclaimer or not, should he be allowed as a reviewer?

      [...]

      So, it OK according to the guidelines. Though, i'd wonder if someone so involved is a good person to actually write such a review.

      I do not understand your comment: "Disclaimer or not". That's precisely why the disclaimer is there -- so that you can make up your own mind about the reviewer! You are a perfect case-in-point! Without the disclaimer, you wouldn't have a clue about the reviewer's past relationship with the author. This way you can

  • But, I want to see how deep the rabbit hole goes!
  • hello world (Score:5, Funny)

    by DohnJoe ( 900898 ) on Wednesday October 25, 2006 @02:40PM (#16583302)
    as a short introduction to the LUA language I present here the code for a hello world app:

    print "Hello world"

    hope that helps...
    • by Shados ( 741919 ) on Wednesday October 25, 2006 @03:05PM (#16583700)
      Thanks, now with this newfound knowledge in mind, I can add on my resume "Intermediate LUA developer"
      • You say LUA Guru.
        Then when they question you, look at them as if they are below you in all ways, then write on the board print "Hello world"
        then say "Is testing my knowledge really an indicator? during an interview? I think not."
        The go on as if you got the job and the interview is just a minor inconvience.

    • Re: (Score:3, Interesting)

      by jhoger ( 519683 )
      No it's
      print ("Hello, world.")

      Reader's Digest guide to Lua:

      -1) I believe it's 'Lua' not LUA
      0) You need the parentheses on function calls.
      a) Only data structure is hash tables
      b) Hash tables with positive integer indexes emulate arrays (order is maintained)
      c) Positive integer indexed hash tables are one-based. Gawd. This makes for some serious unpleasantness if you want to embed Lua in your C application, since many real world things are 0 based and probably all the patterns you know for writing proper loops
      • You got a few things wrong:

        0) You need the parentheses on function calls.
        False, f("a string") is equivalent to f"a string" and f({a = b}) is equivalent to f{a = b}

        a) Only data structure is hash tables
        False, lua tables contain both a hash table part and a pure array part. The runtime figures out how to store stuff internally. As a lua programmer, you never need to care, but if you're only using positive integer keys between 1 and N, with few gaps, it will most likely be stored as an array.

        e) No sem
        • by jhoger ( 519683 )
          I'll grant that 0) is ok, you taught me something. But really, it's a narrow point. There are only two cases (single string parameter or single table constructor argument) where you can leave out the parens, unlike Perl where the cases where you must use parens are the exception. So you get in the habit of always putting them.
          For a) I maintain my statement; the Lua abstraction is an associative array (commonly called a "hash" by Perl programmers). Efficient use of positive integer indexes is a nice optimiza
      • Some other little gotchas:

        m) No built-in Unicode support (Waaak! How can a modern language not support a wide string type!)
        n) Variables are global BY DEFAULT and not local. To declare a local variable you have to say local foo = "blah".

      • No it's
        print ("Hello, world.")

        The GP code works fine:

        Lua 5.1.1 Copyright (C) 1994-2006 Lua.org, PUC-Rio
        > print "Hello world"
        Hello world
        >
  • by HoneyBeeSpace ( 724189 ) on Wednesday October 25, 2006 @02:46PM (#16583406) Homepage
    If you want to geek out a bit and program Lua on your Palm, you may do so: http://netpage.em.com.br/mmand/plua.htm [em.com.br]
  • by Blrfl ( 46596 ) on Wednesday October 25, 2006 @02:49PM (#16583470) Homepage
    Read the article again, and this time remember that "lua" is a word the Hawaiians use for the bathroom.
  • Celestia (Score:5, Informative)

    by Fallingcow ( 213461 ) on Wednesday October 25, 2006 @03:11PM (#16583792) Homepage
    If you need a reason to learn Lua, look no farther than Celestia [shatters.net].

    Lua is the more powerful of the two scripting languages that can be used with Celestia. You can do some awesome stuff with it, and there are lots of examples on various forums (fora?) devoted to Celestia scripting. Good times.

  • lua uses (Score:3, Informative)

    by Anonymous Coward on Wednesday October 25, 2006 @03:21PM (#16583932)
    http://www.lua.org/uses.html [lua.org] list an impressive amount of project (many of them games) using lua.
  • Although Lua's killer app seems to be as a scripting engine for games, it's also a good general-purpose data description language. I used it for that purpose, for a little database where the alternative would have been a csv file, and it worked out well. I would also be interested in people's thoughts about Lua vs Guile. They're both used as scripting engines for a lot of open-source apps, and they're also both good data description languages. Would the main difference be speed? Performance? Licensing? Por
    • I don't know anything about Lua, but portability is a concern for me. I don't use guile because it's next to impossible to compile a recent version on Windows with MinGW, when it should be a piece of cake.

      It's a shame, as I'd really like to be able to use it. But an "extension" language that isn't as portable as the GUI toolkit I'm using (QT) isn't worth the effort IMHO.

      From what little I've read, Lua seems as if it would be a bit more portable.

      • From what little I've read, Lua seems as if it would be a bit more portable.

        Written in very clean C. Tried it with half a dozen compilers and not so much as a warning. If your platform has a C compiler, lua will probably work.
        • Re: (Score:3, Informative)

          by SimHacker ( 180785 ) *

          Absolutely: The Lua interpreter source code is very clean and well written, and wonderfully portable and platform agnostic.

          Here's the source code [lua.org] that you can view online -- there isn't much to it! Four global header files, 19 core C files, 19 core header files, 10 library C files, 1 interpreter C file, and 2 compiler C files. Here is the main loop of the virtual machine [lua.org] -- notice that there are only 38 opcodes [lua.org]!

          A great example of some interesting code written in Lua is the Auctioneer [auctioneeraddon.com] add-on for World

          • by Fred_A ( 10934 )
            While there may be lots of reasons to use Lua and the language may have lots of qualities, this kind of argument is on par with saying Lua is better becase there are fewer "Lua sucks" pages indexed on Google than "<whatever> sucks" so it *just* has to be better.
            A language shouldn't be used "because it's better than language x" but because it's better for a task.

            I certainly haven't been converted over.

            Anyway since all your benchmarks compare everything unfavorably to C, you should be using C by your ow
            • I gave several reasons why Lua is better than Ruby, for many tasks. Most tasks consider speed and memory usage to be important. Also, Lua is much better than Ruby when it comes to embedding it in an application (like World of Warcraft does). And Lua is also very easy to extend the language with C or C++ code and libraries written in other languages, which is useful for a wide range of tasks. And the fact that it's well written and well designed certainly doesn't hurt.

              I still love Python and use it regul

            • by Bastian ( 66383 )
              The grandparen't wasn't saying that Lua's speed on these benchmarks alone is why Lua is the greatest language or anything. However, it does make Lua worth caring about. There are plenty of other reasons to like it - it's a fairly clean language, and in situations where maintainability matters it's probably preferable for a lot of people who don't like, say, perl's terseness and tangled syntax. It's a reflective language, which makes it useful for some more complex tasks than some other scripting language
          • I think it's laughable that someone would put their time into learning a faddishly popular language like Ruby, but would then not consider learning a technically superior language like Lua, since Ruby scores so badly on these benchmarks compared to Lua, Lua has been around a lot longer than Ruby, and it had already proven itself in many commercial products (like WOW).
            That's a total apples-and-oranges comparison. I've used both Lua and Ruby, and liked them both, but there's very little overlap between the
      • by Bastian ( 66383 )
        Lua is definitely more portable, and it's easier to get it to talk to other languages. I had originally looked at Guile for my current app (which does the heavy lifting with Objective-C), and decided against. Judging from the small number of Guile bridges, it looks like Guile doesn't play so nice with languages that aren't substantially similar to C, and even then there seem to be a lot of conditions and complications floating along the boundary between it and C.

        Lua, on the other hand, is happy to run on
    • Lua is a nice language for some purposes, but it has two major limitations. One is that it has no regexp support. It has some limited pattern matching stuff that looks superficially like regexp matching but isn't. This is intentional, in order to keep the footprint small. For game programming you probably don't need regular expressions, but it makes Lua much less suitable than Tcl, Python, or various other scripting languages for anything involved string processing.

      Secondly, Lua does not support Unicode

      • by bit01 ( 644603 )

        Secondly, Lua does not support Unicode, which is a defect not only for text processing but for anything requiring serious localization.

        That's a showstopper for me. In this day and age no language that claims to be general purpose should be without UTF-8 [wikipedia.org] support. English+ASCII covers only a fraction [ling.gu.se] of the world's languages.

        ---

        The patent mafia: When all they've got is a hammer, everything looks like a nail.

      • Secondly, Lua does not support Unicode, which is a defect not only for text processing but for anything requiring serious localization. Misinformation at its finest. *sighs* Lua is natively UTF-8 compatable. It does choke on the BOM in source files, but that can easily be fixed.
        • Unless you've got more up-to-date information than I have, Lua in fact does not support Unicode. It is true that you can kind of, sort of, manipulate Unicode strings in Lua, but to call this ability support is unwarranted. Here is the discussion of the topic from the Lua Users' Wiki [lua-users.org]. It says that the length functions do not return the number of characters in a string, only the number of bytes. It says that Lua's built-in pattern matching does not work on Unicode. It says that there is no notation that allo

  • by mhackarbie ( 593426 ) on Wednesday October 25, 2006 @03:27PM (#16584022) Homepage Journal
    I don't have any association with the author or the other creators of the language, so perhaps my opinion will add some legitimate support for the book and the language. I developed my previous project (Ribosome Builder [sourceforge.net]) with Lua and found it to be very stable, easy-to-use, small, fast and powerful. That said, I was eagerly looking forward to the release of this next edition of the book, because I'm using Lua again for my current projects, and hope to make even better use of Lua 5.1. I'm especially excited about the new support for modules, and also the fact that Lua is now supported by SWIG. Previously, I had to do a lot of manual hacking to define the interface functions between my core code (in C++) and the lua scripts.

    I've read about 3/4 of the book so far and I completely agree with the reviewer's assessment. It's very cleanly and clearly written, with many things explained in a concise and elegant style. For example, Ierusalimschy's explanation of closures allowed me to immediately grasp them and appreciate why they are useful. I remember reading about them way back years ago in Larry Wall's book 'Programming Perl', and was remained rather confused about the concept. I don't know if the additional years of experience helped, but the clear style of the Lua book certainly did.

    Using a scripting language for enhancing and extending a complex project just seems to be a given for most serious projects these days, and after surveying the field, I considered only two main choices: Python and Lua. Python is also really well designed and powerful, but I decided to go with Lua because it does pretty much everything I need it to do, does it very well, but best of all, it is so very small. These days when even the most basic projects can quickly grow into complex, interconnected monstrosities with a zillion dependencies, I believe that the values of small and simple are more important than ever. So for that reason especially, I'm really excited about Lua and the prospect for using it more effectively after I finish swallowing this Blue PIL.

    mhack

    • Python is generally easier to extend than embed; Lua is different in that it's designed to be embedded.
      • Lua has one major advantage over Python, that is it's use in a number of very populer mainstream games. Supreme commander uses it, and that may be enough to get it more populer.

        populer != best, but best is a relative term. Fit for purpose is more relevent. I do like python, but I'm starting to apreciate what lua enables in game modding, in so far as it involves the games I like.
        • by smaddox ( 928261 )
          populer != best, but best is a relative term.

          Yeah, only a geek would think that being best at something is more important than being popular =P
  • The syntax is similar to Pascal. No thanks. Out of all the languages I would be least likely to model a new langauge syntax after, Pascal and Lisp would be near the top.
  • Lua = moon (Score:2, Interesting)

    by Z80a ( 971949 )
    in brazil,from where this script language come from,lua = moon
  • World of Warcraft's UI system is programmed in LUA & something else, can't remember gotta go raid, kthxbye
  • Even if you have no plans to actually program in Lua, you should get this book as an example of how a technical book can and should be written!

    While the novice programmer can certainly pick this book up and learn to program (and it is perfectly suited to that), the examples, asides, and discussion in each chapter contain gems for the intermediate to advanced programmer. Everytime I look something up I see a new depth to some language feature or example I didn't see the first time around.

    I use Lua becau

  • by slonik ( 108174 ) on Wednesday October 25, 2006 @06:32PM (#16586272)
    Well, the first reaction of many people might be
    "O no, yet another scripting language finds it way from the obscurity into the lame light". Do we need an extra one if we already have Ruby, Python, Perl, Tcl, Scheme. And I say -- YES, Lua has its place, it is not redundant, it is not "me too" language. And here is why.

    I have been expert Ruby coder for the last 5 years using Ruby for data modelling, extensive scripting, wrote load-balancing scripts, Rails Web development, binding C++ libraries to Ruby using SWIG, you name it.

    Six month ago I got involved in LUA and I totally fell in love with it.
    What does make a beautiful programming language? Lots of features? wealth of libraries? simplicity of it? I think that language design is more art than science and the language beauty is the careful balance of features, simplicity, semantics, uniformity, etc. Like in a masterpiece painting it is the balance of color, shapes, motives and composition.

    C, for example, ia a beautiful language in the category of "portable assemblers". In that category C is powerful thanks to its libraries, simple and easily implementable thanks to its syntax and semantics, portable due to very clever and clean hardware abstraction.

    I think that Lua is to "high level scripting languages" is what C is to "portable assemblers". Lua has both OO and functional programming very naturally represented in its semantics. All objects are first class (including functions). Lua is small, very fast (in fact fastest scripting language according to http://shootout.alioth.debian.org/ [debian.org]), has very good Virtual Machine, incremental Garbage Collector. As far as fundamantals are concerned, Lua is light-years ahead of Ruby. It still lags behind in library support, but the recent progress is very encouraging.

    Anyway, give Lua a try. You will love it. Lua is nice, its codebase is tiny (about 10K lines). It runs on anything that support ANSI C compiler including embedded stuff (ARM, Palm, Cell phones, MIPS, x86, etc).
  • The best part about this book is how applicable it is to other languages: Even though it doesn't directly touch any others, of course, it introduces things like closures and tail recursion in a very good way for both intermediate programmers and newbs to understand and apply to, say, Perl.
  • "...As a disclaimer, let me say that I'm one of the technical reviewers of the book and I have been working with Lua since 1993, most of the time interacting with Roberto Ierusalimschy, even when not working in the same projects as him..." "...I really recommend this book to anyone interested in learning Lua, and also for those who already know how to use Lua but would like to fully master its way of thinking, the so called "Lua way" of doing things. The book has been considered by many as an excellent gui
  • Every reference to the language I do not know, should contain a special paragraph stating:
    To mapkinase: The uniqueness of this language is this, that, those and these. You should be using it instead of C, C++ and Perl because ...

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