LuaMatthew Spain | Kerry Zhao

Agenda• Overview of Lua

• Language Details

• Application Areas

• Demo

• Conclusion

Overview

History• Made by Roberto Ierusalimschy, Luiz

Henrique de Figueiredo, and Waldemar Celes in 1993

• Members of Tecgraf, PUC-Rio in Brazil

• Brazil had trade barriers making it hard to buy software from abroad

Release TimelineJul 1993 - Lua 1.0Jul 1994 - Lua 1.1 (first public release), paperFeb 1995 - Lua 2.1 (first free commercial release)Nov 2000 - Lua 4.0, no built-in functionsApr 2003 - Lua 5.0, multithreading, full lexical scoping

Dec 2011 - Lua 5.2, current version

Language Influences• Replaces

o DEL (data-entry language)o SOL (simple object language)

• Scheme

• Modula

Resourceswww.lua.orgwww.lua-users.orgcode.google.com/p/luaforwindows

luadist.orgPlugins for most popular IDEs

Language Details

Function• High-level scripting language

• Lightweight - interpreter about 180k

• Embedded language - C API

Execution• Interpreter compiles to bytecode for

Lua VM

• Very fast, usually compiled at run-time

• Programs can be compiled in advance to skip overhead

• Portable, builds on anything with a C compiler

Paradigms• Multi-paradigm

• Imperative

• Functional

• Not object-oriented, but object-like constructs can be made using tables and metatables

Lexical/Syntactical Fun

Reserved Keywords• and

• break

• do

• else

• elseif

• end

• false

• for

• function

• goto

• if

• in

• local

• nil

• not

• or

• repeat

• return

• then

• true

• until

• while

Types• nil

• boolean

• numbers

• strings

• tables

• functions

• userdata

• threads

Control Flow• if...then…else…elseif…end

• for...do...end

• while…do...end

• repeat...until

Assignment• “multiple” assignment

o a, b, c = “this is multiple assignment”, “yep” i.e. a = “this is multiple assignment”, b = “yep”, c = nil

o a, b = b, a a and b have swapped values

o a = a or b if not a, a = b

Tables• EVERYTHING IS A TABLE

Typing and scope• Strongly typed

• Dynamic typing

• local keyword specifies non-globals

• Symbol table easily accessible

Special features• Metatables

• Closures

• Special allowance for object oriented programmers

Metatables• None by default,

added with setmetatable

• Metamethods include:o addo subo mulo divo modo powo unm

o concato len

o eqo lto leo indexo newindexo call

Closures• a function inside of a function

• inner function has access to local variables of the outside function

Object-oriented Features• No classes, only prototypes

• Syntactic sugar for methods:

function table.func(self, args)

can be written as

table:func(args)

Application Areas

Application Areas• GAMING

• Notables include World of Warcraft, FarCry, the CryENGINE2,

Garry’s Mod, Angry Birds

Application Areas Cont’d• IDE’s

• Operating Systems

• Plain Text Editors

• Robotics

Demo

Conclusion

References• The Evolution of Lua

• Programming in Lua, first Edition