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Beginning Lua Programming
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.
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.
Blizzard uses LUA as the scripting language for macros and UI controls in the World of Warcraft MMORPG.
"No one likes working in a hamster wheel, and your shop smells of cedar shavings from here." - TaleSpinner
It is also the scripting language that is used for WoW mods.
What advantage does Lua have over perl/python/ruby/other existing scripting languages that makes it worth investing the time to learn?
SpyDock: Scientific Python in a Docker container
Great example of how lua can extend the functionality of a program. Check out the Nmap Scripting Engine.
With lua and NSE, nmap can now do things like vulnerability testing. Why not download nmap now and give it a try?
Yeah, you forgot the women.
Its also used in Supreme Commander, to script a lot of the in game AI and unit actions as well as define the attributes of moddable units.
"Like anything good, it didn't take long for it to be discovered by others looking for a small and efficient scripting language."
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.
Any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so.
After reading over the Lua home page as well as the wikipedia entry, I'm left wondering if Lua is merely a language for writing extensions or if it's intended for building things (like, say, application frameworks?). The other thing I hope someone here can answer is this: are there no other languages designed for extending other applications? Why can't this be done in Ruby or Python or Perl or JavaScript? Not to offend the tens of Lua programmers reading this, but what's the point? What is it that Lua does better than other languages available for the task?
Neko's API is much more easier to use. What exactly does Lua have that Neko doesn't?
He didn't forget: he's a /. nerd, so clearly women never entered his mind.
Yeah, I agree. That was lame, lame, lame.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
You mean just like the US of A??
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.
http://zero-to-enterprise.blogspot.com/
As a Brazilian, I can say you are really not trying.
Mardi Gras?
There is no such thing in Brasil. I guess you mean carnival, it differs from mardi-gras in the ammount of naked people (and crossdressers).
Nazi hideout?
I think you confused Brazil with Argentina. 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).
Should you use it for your online web application backend, or your system administration scripts? Probably not.
The World Wide Web is dying. Soon, we shall have only the Internet.
to turn it into a bloated monstrosity because it would be so much more useful if it just did this one tiny little additional thing.
Deleted
Yeah, the soccer was a definite miss, but for those of use who think a work out is more than just moving a desktop from one cubicle to another, brazilian ju-jitsu is not only a great workout, but one of the best and most usable martial art out there. I would say that with the rise of MMA in this country, more Americans would relate BJJ with Brazil than soccer.
(yes, this is an Americentric post)
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
If you want to add scripting functionality to an existing application Lua is by far the easiest way to do so, and it has an added benifit being more efficient (both in terms of memory consumption and execution speed) than python or ruby. It is fairly easy for power-users to learn, as it is simular to javascript in many ways, and yet is also powerfull, as it is a complete functional language. For these reasons, you are seeing it being used more and more in open source desktop applications as well as many big name games such as WoW.
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.
>'Lua' means 'moon' in Portuguese and is pronounced LOO-ah.
I guess all the Americans here didn't get it.
thegodmovie.com - watch it
Brazil is famous for martial arts? WTF?
Asking what Lua has over Perl/python is like asking what YAML has over XML. You can do more in XML but it's not a lightweight format. YAML is clean and human readable, and fast to parse. It's so lightweight that I actually use it in my Python program to define complex structures of constants, since it's actually a cleaner syntax than the python code itself!
.plist files on macs ought to be YAML. this would make a much better bridge between unix flat file configs and the desired database style configs that .plist achieve. (On the other hand things like markup languages for complex text layout are apropos for XML. my point is very few places benefit from XML.)
Indeed there are extremely few XML applications I have seen that would not be much better served by YAML. for example,
So the analogy here is that sometimes simpler is more useful than full featured. the trick is getting the most out of the least, not simply removing features from the complex form. Besides which To the extent that YAML is turing complete it's as good as anything else. Just as YAML can in principle represent anything that XML can.
Some drink at the fountain of knowledge. Others just gargle.
It's also the scripting language used by Supreme Commander.
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).
:)
MMA is pretty popular in the states. Pre-MMA days, the first things I thought of when I heard Brasil was the Soccer team and hot women. Now I think of BJJ first, because BJJ was just that dominant in the early UFCs. As for martial artists not knowing BJJ outside of MMA, I have an article about Helio Gracie being in the longest fight ever from a Karate magazine around 1990, before the first UFC in America. I have to admit, I had no idea what to think when I read it as a kid, other than it had to be a boring fight.
...plastic surgery...
--I'm so big, my sig has its own sig.
-- See?
Don't forget waxes!
Having spent many years with Perl, then Python, and finally Ruby, I discovered Lua recently at v5.1, and *love* the language. Lots of people already mentioned that it is used heavily as an embedded language, but, it was designed as an 'extensible' language, lending itself to creating DSLs with ease. One of the fastest scripting languages, it is also one of the smallest: the whole distribution fits on a floppy disk (if you still use those).
Although there is good progress with the Kepler project, there is not yet a sparkly project like 'Rails' that actively promotes the language.
Java does too http://lejos.sourceforge.net/
I don't think there are python or ruby ports though, possibly because these devices are very limited.
Engineering is the art of compromise.
There are other things that Brazil should be known for...
1.) They are the nicest people one would ever want to meet, with qualities rarely found in North America such as humility, and spontaneous warmth and friendliness.
2.) They make excellent beer.
3.) Massive government corruption... In spite of the fact that perhaps up to two thirds of all politicians at all levels of government are corrupt, Brazilians vote them back into power time and time again. Though Brazilians can always get up a crowd to demonstrate against George Bush (who has nothing to do with this), they couldn't get off their butts to protest or demonstrate against their own corrupt leaders. They rather just complain about it and pretend that this is something beyond their control. Fiscal waste and corruption alone must be costing their GDP a good 20 percent.
4.) Brazil is totally inept at conserving its nature preserves and forests. Often there has been illegal cutting on grand scale in some forest reserve for a decade before arrests are made. Entire river systems with millions of fish are wiped out in an instant after some toxic spill. Thousands of fishermen become unemployed overnight, and people who depended on the fishery are suddenly starving and depending on handouts, but the perpetrator is never caught.
5.) Their justice system simply doesn't work very well. It takes so long to receive justice that people grow old and die before receiving fair compensation. The crooked politicians seem to never actually end up in jail. Criminals who commit heinous crimes serve little time before they are out again on holiday passes, then disappear.
6.)Oh - did anyone mention the beautiful women?
It also has a VAST disparity of wealth between an elite upper class and an utterly destitute lower class.
If you look at languages like C then having an array start at 0 makes sense, because the array index is the offset from the beginning of the array. However, if you don't have pointers, it's really unintuitive to have arrays starting at 0.
Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
We've learned over and over on this board that there's only one litmus test for a language's commercial success: whether people are adopting it and using it for business, NOT academic, purposes. Lua has been in the mainstream for game scripting for some time now.
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. Richard Stevens. The two books are both very good, but I think serve slightly different audiences. BLP is a comprehensive book filled with gradual, well thought-out examples that can pretty much lead anyone through Lua regardless of programming experience, and help them to learn it well. The PIL book is written for more experienced/professional programmers who don't need as much hand holding.
Despite being a small language, Lua sports some serious language features, and you will be sorry not to learn them all. This is where the two books differ I think. PIL assumes at least a nodding acquaintance with concepts such as closures, iterators, generators, and more advanced concepts such as its coroutines (which are a somewhat extended form of blocks in Ruby). If you are not familiar with these, BLP will ensure that you come away with a full understanding through a battery of examples and patient prose.
That said, people who are already familiar with the above (through prior experience with languages such as Ruby or Python, for example) might find BLP a little slow. This is where PIL really shines. PIL is an extremely well-written book by the Lua's principle architect which provides a full treatment of the language in an economy of pages. It is hard to believe when reading the text that English is the author's second language. The examples are all very good, well chosen, but not excessive. The book moves at a steady pace and covers the same ground in much less space than BLP. One place where PIL really shines is on covering the C API and C programming aspects of Lua. In this respect, it is clearly superior to BLP. But again, you have to be a well-grounded C/C++ developer to appreciate this.
As I said, I own them both. I read PIL first which got me embedding Lua in C applications in no time, and then went back and read BLP to round out and sharpen my skills in the language proper. I think the books can complement each other in this way. They are both above average books.
And now for those who have not used Lua and wonder why they would want to. Lua is a tiny, standalone language/interpreter that can be put almost anywhere. It is an ideal way to extend your application as the entire language and libraries fit into a single library under 200Kb in size. It is written in ANSI C and is extremely portable. In my opinion, Lua is not a language you would choose instead of Ruby or Python (unless of course you were already very proficient at it), as I think those languages have much more to offer in either syntactical elegance or extensive standard libraries. Lua's function as a language is very similar to SQLite's function as a database. It's a powerful little multitool you can use to dramatically enhance and extend your applications with very little effort. A feature that might take 3,000 lines of C might take 10 lines of Lua. My experience with it so far has been very positive, and it has pretty much become a staple in my programming repertoire. It is the ultimate compact domain specific language.
http://uncyclopedia.org/wiki/User:Steve_Ballmer
The syntax is just way too overblown - but then us Smug Lisp Weenies know that anything more than parens and a few lexical markers is overblown.
That is all.
btw, A big chunk of Adobe Lightroom's UI was written in Lua. You can google for more information.
Wrong...many Nazis went to Brazil.
the ammount of naked people (and crossdressers)
Doesn't that make them cross-undressers?
sic transit gloria mundi
Hmm, that's one point of view.. another one is that nerds have to keep track of ALL variables. :D
and of course, being this slashdot, we will of course mention Brazil and recall it maybe by its coffee or Football/soccer, but not because of brazil's mulatas/garotas....
There are two things that make Lua different/better than existing scripting languages, IMO:
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 languages worth their salt can embed data, Lua is *designed* around this feature. The use of tables as a built-in data type is key here.
If you like, you can think of Lua as a more flexible XML, an easily embedded scripting language, or some combination of both.
Irony: Agile development has too much intertia to be abandoned now.
Indexes starting at 0 might be unintuitive to people who aren't programmers, but it gets rid of a lot of +1s and -1s in your source code.
GCHQ Quantum Insert installed. If only our tongues were made of glass, how much more careful we would be when we speak
It is not even known by it's Martial Arts
Umm, Capoeira?
http://en.wikipedia.org/wiki/Capoeira/
> However, if you don't have pointers, it's really unintuitive to have arrays starting at 0.
Tell that to the modulo function. Or pretty much _any_ kind of index arithmetic. Would you rather do 28*i+7*j+k to do a mapping of threedimensional indices to one-dimensional, or 28*i+7*j+k-35? What about backwards?
k = n mod 7
j = (n div 7) mod 4
i = n div 28
or
k = 1+((n-1) mod 7)
j = (((n-1) div 7) mod 4) + 1
i = ((n-1) div 28) + 1
?
Just junk food for thought...
I wondered this myself, learning Java. Since Java abstracts from memory and hides pointers from us, why do array indices start with 0? However, building Tetris, I became very glad of this. (Think about the position of the blocks). I'm sure there are other reasons it makes sense....
I used to carry a bottle of whiskey for snake bite. And two snakes. -Nefarious Wheel
Lua's C API is rather stellar. It makes it very easy to jump between Lua and C code near-infinitely, to access C functions from Lua and Lua functions from C, often nested multiple times that way.
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.
Another scripting language to do what the other bajillion could do with a few libraries.
AHHHHH! When will it end!?
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
Lua is a great little language, unfortunately the runtime changes drastically between versions. While this keeps it small, powerful and fast (especially Mike Pall's luajit) it means your apps are going to have a limited lifespan on supported runtime.
If the developers could at least maintain ABI stability so library bindings work between versions then we'd see lua gain serious traction outside of gamedev. The luajit gives mono a run for it's money in shootouts, and register based VMs are better suited to dynamic languages.
... Brazilian Jiu Jitsu exists (we in Brazil don't call it that, we call it only Jiu Jitsu).
Obligatory Simpsons' quote:
Homer: I have a bladder the size of a Brazil nut.
Taxi Driver: We just call them nuts here.
How could you all forget about Garry's Mod? Basically a bunch of in game mods are built from Lua along with custom weapons and tools.
Lua is also used in garry's mod (Valve Source Engine physics sandbox mod)
It's embedded. Thus, any features you want to add, you'd add to your main app and call them from within Lua.
Don't thank God, thank a doctor!
What advantage does Lua have over Scheme?
And what's with the "it didn't take long" nonsense? Lua isn't exactly new ya know.
>> Small and efficient? Sure, for now. But wait until the rest of the OSS community gets done with it.
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 many extremely bright people, totally immersed in the language and able to make it do the most incredible things. And these very bright people naturally make many very insightful and valuable suggestions about what should be added to the language to make it ever better and more consistent and flexible.
And they are *ALL* ignored by the author, Roberto. And they don't care.
And that is what is odd about the Lua community. It is utterly static, stagnant and neutered, because the language's author might as well be carved out of stone, petrified, entombed in carbonite and held in a stasis field, for all the suggestions he accepts. Which is none, zero, the empty set. Ever.
(I'm excluding bug fixes; he does react to bug reports, but takes nothing else on board, regardless of source, merit, the number of people asking for it, nor the number of years over which they have been asking. It matters nothing to him, because ideas are only allowed to come from his own brain, full stop. He happily discusses everything, but adds absolutely nothing to *HIS* language as a result of those high-volume disussions. It's been so for many, many years, and it's now engrained in that community.)
So there you have it. Lua is an open-source language, but it does not have an open design. The design is utterly closed, and its author is immoveable. And the fanboys, like all fanboys everywhere, don't care, even when they themselves have been making the insightful suggestions which are always ignored.
So you see, there is no danger of Lua becoming bloated with open-community improvements. Because the openness stops dead at the foot of the author. There is not the slightest chance of any community-led improvements, at all.
Can you fit your Perl/Python/Ruby interpreter in 150 kilobytes?
No, but SIOD 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.
To a Lisp hacker, XML is S-expressions in drag.
One should add to that that Brazil has one of the largest aircraft manufacturers in the world. 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 has been totally developed in Brazil.
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).
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?
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Appropriately enough called ``LuaTeX'':
http://www.luatex.org/
Makes easy a lot of things which had required some bizarre texniques.
William
Sphinx of black quartz, judge my vow.
Such as Company of Heroes, Dawn of War, Homeworld.
The vendetta-online space MMORPG also uses Lua at it's core.
Adobe uses it too, in Lightroom
Lua is used in ion3 (a window manager). It's very easy to learn if you're already experienced in a programming language and is quite powerful (most people here probably wished at one time for the possibility to use code in some configuration file)
It has to do with two very basic properties of natural numbers: Cardinality and Ordinality.
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.
I might be missing something, but I've yet to see the name "Embraer" in any of these threads.
Why would you go to this rather than rebol? Which seems to have the advantage of offering easy to make guis as well. Whereas for a user interface don't you have to go to something like murgalua with Lua? Or are there other short cut gui designer environments for Lua?
No, but SIOD 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.
Yes, and I remember SIOD fondly, but I think Lua is still a better choice. I slightly prefer SIOD's syntax to Lua's, but Lua's syntax is going to be far easier to pick up for programmers that have grown up on Java and C++. In terms of built-in data structures, I think Lua beats SIOD hands down, both in terms of usability and familiarity.
Over a 100 comments but noone has realized that it's a real-time scripting language.
Many companies (including the one I work for) use Lua to extend compiled code on real-time industrial machines. Some even program everything in Lua.
TomsRtBt adopted lua to smash down the code size of some of the linux utilities.
Hello? Anybody in there? Rio is known for Chicks! And tiny thongs! And Ipanema! And Copacabana! And Samba!
Geeks. Geez.
668: Neighbour of the Beast
That ANSI-C compatibility will make it kind of annoying to implement any sort of OO interface to your app, though :/ My advice is to go with embedded python, unless you REALLY need an interpreter in 150k.
not know by it's martial arts
so what would you call capoeira? a carnival dance????
IT IS a martial art!!
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 traditional convention of a gap-less ordered array is dropped. And since embedded scripts (Lua's domain) are supposed to be very minimal, self-documenting "to-the-point" code, it would only help if the collections focus was more pervasive from day zero (heh).
http://zero-to-enterprise.blogspot.com/
Honestly, I wonder in which caves some people live ....
IANAL but write like a drunk one.
The first airplane was presented to the world in 1906, publicly, in Paris, by Alberto Santos Dumont, a Brazilian, so, before Wright brothers. The airplanes used until today, are based on a renewed model, named "Demoiselle", a brazilian airplane, presented to the world in 1907. Wright brothers presented their airplanes only in 1908 to the world, in Paris, and they have only a photo to proof it, "presumable" of 1903, to try "patent" the supposed invention. So who have/deserve the credits?
I'm picking Python here because it's powerful, flexible, fast, and should have bindings to everything needed, even on Windows.
Other than that, how do you pick a language? Do you just go for whatever was popular in school?
Don't thank God, thank a doctor!