Lua Matthew 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 Timeline Jul Lua 1.0 Jul Lua 1.1 (first public release), paper Feb Lua 2.1 (first free commercial release) Nov Lua 4.0, no built-in functions Apr Lua 5.0, multithreading, full lexical scoping Dec Lua 5.2, current version

Language Influences Replaces o DEL (data-entry language) o SOL (simple object language) Scheme Modula

Resources code.google.com/p/luaforwindows luadist.org Plugins 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 add o sub o mul o div o mod o pow o unm o concat o len o eq o lt o le o index o newindex o 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

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