tonigonenstein - Slashdot User

Comment Re:BitTorrent Inc. concept flawed from the start (Score -1, Troll) 115

by tonigonenstein on Tuesday April 03, 2007 @01:57PM (#18590859) Attached to: BitTorrent Inc. Introduces Ad-Supported Downloads

However, if you have a half-decent revenue model, such as advertising, revenue easily offsets the bandwidth costs of distributing video from a central server over HTTP, so why put your users through the pain of having to install a piece of client software?

BitTorrent's problem is that anyone that can afford to pay them for their services can probably afford to distribute their content over HTTP from a centralized server, and why wouldn't they given the much lower barrier to entry for their users?

lines 5-7: warning: redundant paragraph.
lines 1-3: point previously made here.

Submission + - Beginning Lua Programming

Submitted by

Simon P. Chappell

on Friday March 30, 2007 @10:02AM

Simon P. Chappell writes: "These days, Brazil is no longer just on the map for it's 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.

This is definitely a book targeted at those new to Lua. But, 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."

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