Introduction to Lua Programming
Written By: S Kokila
- 31 Aug 2007 -
Description: Lua is a powerful, light-weight programming language designed for extending applications. Coupled with it being relatively fast and having a very lenient license, it has gained a following among game developers for providing a viable scripting interface. It has been used in games such as World of Warcraft and Far Cry, and in applications such as Adobe Photoshop Lightroom and Snort.
- What is Lua?
- Getting Started
- Identifiers, Types, and Values
- Variables and Expressions
- Operators
- Statements and Assignments
- Control Structures
- File I/O
What is Lua?
Lua is a powerful, light-weight programming language designed for extending applications. Lua is also frequently used as a general-purpose, stand-alone language. It is dynamically typed, interpreted from opcodes, great facility to handle strings and other kinds of data with dynamic size, and has automatic memory management with garbage collection, making it ideal for configuration, scripting, and rapid prototyping.
Lua is easily extended not only with software written in Lua itself, but also with software written in other languages, such as C and C++. Lua is also a glue language. Lua supports a component-based approach to software development, where we create an application by gluing together existing high-level components, written in a compiled, statically typed language, such as C or C++; Lua is the glue that we use to compose and connect those components. However, unlike other glue technologies, Lua is a full-fledged language as well. Therefore, we can use Lua not only to glue components, but also to adapt and reshape them, or even to create whole new components.
When to use Lua?
Lua is not the only scripting language around. There are other languages that you can use for more or less the same purposes, such as Perl, Tcl, Ruby, Forth, and Python. The following features set Lua apart from these languages; although other languages share some of these features with Lua, no other language offers a similar profile:
- Extensibility: Lua's extensibility is so remarkable that many people regard Lua not as a language, but as a kit for building domain-specific languages. Lua has been designed from scratch to be extended, both through Lua code and through external C code. As a proof of concept, it implements most of its own basic functionality through external libraries. It is really easy to interface Lua with C/C++ and other languages, such as Fortran, Java, Smalltalk, Ada, and even with other scripting languages.
- Simplicity: Lua is a simple and small language. It has few (but powerful) concepts. This simplicity makes Lua easy to learn and contributes for a small implementation. Its complete distribution (source code, manual, plus binaries for some platforms) fits comfortably in a floppy disk.
- Efficiency: Lua has a quite efficient implementation. Independent benchmarks show Lua as one of the fastest languages in the realm of scripting (interpreted) languages.
- Portability: When we talk about portability, we are not talking about running Lua both on Windows and on Unix platforms. We are talking about running Lua on all platforms we have ever heard about: NextStep, OS/2, PlayStation II (Sony), Mac OS-9 and OS X, BeOS, MS-DOS, IBM mainframes, EPOC, PalmOS, MCF5206eLITE Evaluation Board, RISC OS, plus of course all flavors of Unix and Windows. The source code for each of these platforms is virtually the same. Lua does not use conditional compilation to adapt its code to different machines; instead, it sticks to the standard ANSI (ISO) C. That way, usually you do not need to adapt it to a new environment: If you have an ANSI C compiler, you just have to compile Lua, out of the box.
For detailed information on Lua, please refer to the book Programming in Lua by Roberto Ierusalimschy, and Lua’s official site www.lua.org.
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