lua programming

8/3/2019 Lua Programming

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Beginning

Lua Programming

Kurt Jung and Aaron Brown

1 S O 7

© W IL E Y

2 O O 7

Wiley Publishing, Inc.



Conten

Acknowledgments Introduction

Chapter 1 : Ge tting Situa ted

Choosing How to Install Lua

Building Lua Yourself Selecting Prebuilt Lua

Finding Your System's Shell

Windows Shel ls She l ls on Unix and Unix-Like sys tem s

Shel l Features

The Envi ronmen t

Environment Variables on Unix-Like System s

Environment Variables on Windows

Dealing with Tarballs and Zip Files Compiling Lua

The Lua Source Tarball Compiling Lua on Linux and Other Unix-Like Systems

Compiling Lua on Windows Building Lua with Microsoft.Visual C++

Building Lua with the Tiny C Compiler

Building Lua with MinGW

Binary Packages Selecting a Prebuilt Binary Package Installing a Prebuilt Binary Package on a Unix-Type System

Installing a Prebuilt Binary Package on Windows Additional Tools

Programmer's Editor Revision Control System

Summary

Chapter 2 : First Step s •

Numbers and Arithmetic Operations: Basic Interpreter Usage Addition, Subtraction, Multiplication, Division, and Exponentiation Interacting with the Interpreter

Other Notations for Numbers



Contents

Interpreter Know-How

Quitting the Interpreter

Interpreter Shortcu ts

Numerical Gotchas

Division by Zero and Overflow

Floating-Point Rounding

Variables and Assignment

Assignment Basics

Multiple Assignment

Variables on the Right Side of Assignm ents

Strings

Quoting Strings

Quoting Strings with Double Quotes

Quoting Strings with Single Quotes -

Quoting Strings with Square Brackets

Backslash Escaping Relational Operators and Boolean Values

Comparing Numbers

Comparing Strings

The nil Value

Boolean Operators

The and Operator

The or Operator

The not Unary Operator

The Conc atenation, Length, and Modulo Operators

The String Concatenation Operator The Length Operator

The Modulo Operator

Au tom atic Conversion of Operands

Precedence and Associativity

Variables and Values

Comments

Expressions and State m ents

Compound Statem ents

The if Statemen t

The while Loop

The for Loop

The repeat Loop /

The break and do Statements '

Summary

Exercises

XII



Contents

Looping through Tables 124

Tables of Functions 128

The Table Library 128

table.sort 128

table.concat 131

table.remove 132

table.maxn 132

Object-Oriented Programming with Tables 133

Functions with Variable Numbers of Arguments 136

Defining Vararg Functions 136

Scripts as Vararg Functions 140

Keyword Arguments 143

Different but the Same 144

Table Equality 144

Avoiding Bugs by Understanding Mutability 145

Variables and Mutable Values 145

Tables and Functions 147

Copying Tables 148

Building Other Data Structures from Tables 152

Custom-Made Loops 158

Global Variable Environments 163

Summary 168

Exercises 169

Chapter 5: Using Strings 11 1

Basic String Conversion Functions 171

String Length 173

Converting Between Characters and Character Codes 173

Formatting Strings and Numbers with string.format 174

Input/Output 180

Writing to and Reading from a File 181

Pattern-Matching 185

Searching for a Specific String 186

Matching Any of Several Characters 186

Matches of Varying Lengths 193Captures 198

Matching Balanced Delimiters 202

More on string.find, string.match, and string.gsub ' 202

Iterating Through All Matches 204

Tricks for the Tricky 207

Magic Characters Chart 209

Summary 210

Exercises 210

xiv



Conte

Chapter 6: Handling and Avoiding Errors 2

Kinds of Errors

Syntax Errors

Runtime Errors

Handling Errors

Default Error BehaviorCheck ing Assumpt ions

Code Errors

Data Errors

The assert and error Functions

Defining Your Own Error Condition

Ant ic ipat ing Error Condi t ions

Working wi th Return Values

St ructur ing Code

Error-Containment Funct ions

The pcall Function

The xpcall Function

User-Written Scripts

Locating Errors

Summary

Exercises

Chapter 7: Using Modules

Interfaces and Implementations The require Function

Where to Put Modules

Creating a Module Directory

Setting Lua's Environment Variable

Preserving a Module's Interface

Module Bookkeeping

Bytecode

Namespaces

Creat ing and Reusing Namespaces

Avoiding Global Variables •Using the s trict Module

Reporting All Global Assignments

The module Function •

C Modules

Summary

Exercises



Contents

Chapter 8: Extending Lua's Behavior w ith M etam etho ds 2 4 9

Using Concatenation and Arithmetical Operators on Tables 24 9Relational Metamethods 257Indexing and Call Metamethods 2 5 8Non-Tables with Metamethods 265

Non-Syntactical Metamethods 267Metamethod Applicability . 2 6 8Summary 268Exercises 269

Chapter 9 : Handling Events Naturally with Coroutines 2 7 1

Coroutines and Program Control 2 7 1Coroutines Are Not Functions 27 2

How Coroutines Are Like Programs 27 2

Coroutines Transfer Control 27 3Wrapping a Coroutine 27 3

Corout ines Are Cooperat ive 2 73

Outside Looking In 27 5

Corout ines Have Statu s 2 7 8

Rules of Conduc t 2 79

Work Shoulder-to-Shoulder 27 9

Trust the Dispatcher 28 0

Expect the Best, Prepare for the Worst 28 0

Play on Your Side of the Fence 28 0

Avoid the Deep End 2 8 1Managing Concurrent Tasks 2 8 1Retaining State 2 82

Exercising a Coroutine's Memory 28 2

Iterating with Coroutines 28 6

Handling Events Simply 2 8 7

The Event Loop 288

Yielding to Another Coroutine 29 6

Summary 297Exercises 297

Chapter 1 0 : Looking Under the Hood 2 9 9

Bytecode and luac 29 9Garbage Collection 303The Implementation of Tables and Strings 307

XVI



Conte

The Debug Library 3

Inspecting and Manipulating Running Code 3

Hooks 3

Other Functions in the Debug Library

Summary 3

Exercises

Chapter 11: Exploring Lua's Libraries 3

Core Library 3

Environment Functions 3

Metatable Functions 3

Chunk-Loading Functions 3

Error-Containment Functions 3

Module Functions

The Garbage-Collection Function , 3Type and Conversion Functions 3

Basic Output 3

Error-Condition Functions 3

Table Traversal Functions 3

Vararg-Related Functions 3

Coroutine Library 3

Package Library 3

String Library 3

Pattern-Based String Functions 3

String-Conversion Functions 3Table Library 3

Math Library 3

Trigonometric Functions 3

Inverse Trigonometric Functions 3

Hyperbolic Functions

Exponent Functions 3

Logarithm Functions 3

Adjustment Functions 3

Floating Point Representation 3

Angle Conversion FunctionsPseudo-Random Number Functions 3

Modulus Functions 3

Minimum and Maximum Functions ' 3

Constants 3

Input/Output Library 3



Contents

Operating System Library 368

CPU Tim ing 368

Time and Date Functions 368

Filesystem Functions 369

Other Operating System Functions 370

Debugging Library 370

Summary 37

Chapter 12: Using Community Libraries 375

Library Overview 375

Dynamically Linked Libraries 37

Resolving External References 37

Configuration Options 37

Librar ies Bui l t f rom Source Code 37

Building Libraries onUnix-Like Systems 37

Building Libraries on Windows 37

L imi ts to Portabi l i ty 37

How Lua Interacts with Libraries 37

The Variable Registration P rocess 379

Calling a C Function from Lua 38

The pack Binary Structuring Library 38

Building the pack Library on Unix-type S ystems 38

Building and Installing the pack Library on Windows 38

Testing the pack Library 38

Installing the pack Library 38

Using the pack Library 38

The cU RL F ile Transfer Library 38

Building libcurl 38

Building libcurl on Unix-Like Systems 39

Building libcurl on Windows 39

Building luacurl 39

Building luacurl on Unix-Like Systems 39

Building luacurl on Windows 39

Using luacurl 39

The gd Graphics Library 39

Bui ld ing gd 39

Building gd on Unix-Like System s , 39

Installing gd on W indows ' 39

Building lua-gd 39

Building lua-gd on Unix-Like Systems 39

Building lua-gd on Windows 39

Using lua-gd 39

xvi i i



Conten

The SQLite Database Library 4Bui ld ing SQLi te3 4

Building SQLite3 on Unix-Like Systems 4

Building SQLite3 on Windows 4

Bui ld ing Iua-sql i te3 4

Building Iua-sqlite3 on Unix-Like System s 4

Building Iua-sqlite3 on Windows 4Using Iua-sql i te3 4


Chapter 1 3 : Interfacing Lua with Other Languages 4

How C Programs Use Lua 4Embedding Lua 4

Extending Lua 4

Embedding or Extending: Which Is Best? 4Comm unicating Between Lua and C 4Calling Lua from C 4

Obtaining a Lua Function 4

Calling a Lua Function 4

Protected Calls 4

Working with Userdata 4Indexing Values in C 4

Retrieving Indexed Values 4

Setting Indexed Values 4

Retaining Values in C 4The Registry 4

C Function Environments 4

Upvalues in C 4

Referencing Values 4

The Thread Environment 4

Layering Your Extension Library 4Summary 4Exercises 4

Chapter 1 4 : M anag ing Information with Databases 4

Some Basic Relational Database Concepts • 4SQL, LuaSQL, and MySQL 4Summary 4

Exercises 4



Contents

Chapter 15: Programming for the Web 4

A Web Server Primer 4

Dynamic Web Content 4

Embedded Web Server 4

Extended Web Server 4

Creating Content at Run Time with Lua 4Executing CGI Scripts 4

CGI Scripts on Unix-Type Systems 4

CGI Scripts onWindows 4

Installing a Web Server 4

Apache '

TinyWeb 4

Testing Your Web Server with Static Content 4

Serving Dynamic Web Content 4

Problems w ith CGI Scripts 4

Asynchronous Calls to the Server 4

Producing a Calendar Dynamically 4

Producing Charts Dynamically 4

Interactive CGI Applications 4

CGI Helper Routines 4

Developing CGI Scripts 4

Security Issues 4

The Kepler Project 4

CGI the Kepler Way 4

Lua Pages 5Summary 5

Exercises 5

Chapter 16: Connecting to a Larger World 5

Installing LuaSocket 5

Compiling LuaSocket 5

Compiling on Linux and Other Unix-Like Systems 5

Compiling on Windows 5

Installing Windows Binaries 5Network Overview 5

Routed Packets 5

Addresses '• 5

Domain Names 5

Identifying Internet Resources 5

Transport Protocols 5

Sockets: Streams and Datagrams 5

TCP Socket Sociology 5

XX



Conten

Using LuaSocket for Network Communication 5

Handling Multiple Persistent Connections 5

Using Lua Coroutines with the select Function 5

Multiple Connections on the Server Side 5

Setting Timeout Values for the Server Socket 5

The Application Protocols 5

Filtering the Flow of Data 5

Accessing Web Pages 5

Sending and Receiving E-mail Messages 5

Networking with Lua and Streams 5

On the Server Side: inetd and Friends 5

On the Client Side: ssh and Friends 5

Summary 5

Exercises 5

Chapter 17: Programming Games with Lua 5

Understanding Why and When to Use Lua 5

Simple 2-D Action Game Using SDL 5

Installing SDL and LuaCheia 5

Using SDL 5

Summary 5

Exercise 5

Chapter 18: Carrying Lua with You 5

Getting Started with Plua 5

Obtaining Plua 5

Examining the Distribution Contents 5

Exploring Plua's Features 5

Running the Plua Application 5

Saving Plua Programs 5

Reading the Online Documentation 5

Using Palm OS Streams 5

Compiling Applications 5

Compiling Libraries5

Plua on the Mothership 5

The Command-Line Compiler 5

The Palm OS Emula to r •

Obtaining the Emulator

Installing on W indows

Configuring POSE

Running Plua in the Emulator



Contents

Compiling a Program in the Emulator 58

Exiting th e Emulator 58

The Palm OS Simu la to r 5 8

Obtaining the Simulator 5 8

Using the Simulator . 5 8

Programming with Plua 5 8Generating Graphics 58

Programming the User Interface . 58Accessing Databases 59


Chapter 1 9 : Fitting into th e Lua Com munity 5 9

The Lua Web Site 59

The Lua Reference Manual 59Framing Questions 59The Lua Mailing List 59

Viewing and Searching the Archives 59

Downloading the Archives 59

Using a Web Browser to Access the List 59

Using a Newsreader to Access the List 59

Subscribing to the List Server 59

Posting Messages 60

The Lua Chat Room 6 0

Forums 60The Lua Wiki 6 0

LuaForge 60Annual Workshops 60Summary 60

Appendix A: Answers 6 0

Index 62

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