A Brief Introduction to Lua Scripting
The First Step to World of Warcraft's Interface Customization
Jun 24, 2009
The most interesting thing about the Lua scripting languages is not that:
- Lua is free to download, install and use
- Lua is open source
- Lua is small and fast
- Lua is portable
- Lua is embeddable
- Tiobe reports that Lua is the 20th most used programming language (as of June 2009) with 0.557% of programmers using it
- Lua is Portuguese for “Moon”
No, the most interesting thing about Lua is that it is used by more people than there are living in Belgium, and they don't even realize it.
How can the Number of Lua Users be Greater than the Population of Belgium?
One reason for Lua's success is that it is used as part of the interface customization for World of Warcraft (WoW), and it's an interesting fact that:
- the current population of Belgium is 10, 403, 951
- the current population of World of WarCraft (WoW) is 11 million
As well as World of Warcraft, Lua is used in (to name but a few):
- Adobe Photo Lightshop
- Apache
- Baldur's Gate
- Damn Small Linux
- Heroes of Might and Magic
- MySQL
- SciTE
- Supreme Commander
So, obviously Lua must be very complicated to use? Well, no, it's not. And that is why Lua is so powerful – it can be used as easily in a small scale development in Windows as a complex application targeted for a Playstation or a GameCube.
Installing Lua
The Lua installation application can be downloaded directly from the a href='http://www.lua.org'>Lua web site. It's worth noting that Lua requires the Microsoft Visual C++ 2005 SP1 redistributable to be installed as well (although the installation process will attempt to do that if the redistributable is missing and the user's computer is connected to the Internet).
A Simple Lua Script
Lua comes with its own command line interface, and so, once Lua has been installed the programmer can click the desktop shortcut to Lua, or start a command prompt and then type 'lua'. It's then just a matter of trying out some scripting (as can be seen in figure 1 at the bottom of this article):
Once the obligatory 'Hello World' has been tried out then it can be turned into a function:
Which can then be called by typing:
And, of course, the programmer will then want the function to accept inputs:
This is run by typing:
If this code is now saved to a file (for example c:\lua\hello) then it can run from any command prompt (as shown in figure 2) by typing:
At this point the programmer can relax with a nice cup of Moca, look at WoW and say “I know how that all works”. Well, maybe not, but at least they'll have taken their first steps down that road.
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