Table of Contents

1 C for Perl programmers 1

1.1 Hello, world 1

1.2 The C compiler 2

1.3 Header files 3

1.4 The main function 4

1.5 Variables and functions 6

Function parameters 6, Automatic variables 7, Global variables 8, Static variables 9

1.6 Data types 10

C types 11, Types defined in Perl 15

1.7 Casting 16

1.8 Control constructs 17

Statements and blocks 17, The break and continue statements 18, The switch statement 19

1.9 Macros and the C preprocessor 20

1.10 Library functions 23

1.11 Summary 23

2 Extending Perl: an introduction 24

2.1 Perl modules 24

Module distributions 26

2.2 Interfacing to another language: C from XS 30

The Perl module 30, The XS file 31, Example: ?Hello, world? 32, Return values 36, Arguments and return values 37

2.3 XS and C: taking things further 38

Modifying input variables 38, Output arguments 39, Compiler constants 40

2.4 What about Makefile.PL? 44

It really is a Perl program 47

2.5 Interface design: part 1 47

Status and multiple return arguments 48, Don?t supply what is already known 48, Don?t export everything 49, Use namespaces 49, Use double precision 49

2.6 Further reading 50

2.7 Summary 50

3 Advanced C 51

3.1 Arrays 51

3.2 Pointers 53

Pointers and arrays 55, Pointers to functions 57

3.3 Strings 58

Arrays of strings 59

3.4 Structures 60

3.5 File I/O 62

3.6 Memory management 63

Allocating memory at runtime 64, Altering the size of memory 65, Manipulating memory 65, Memory manipulation and Perl 67

3.7 C Traps for the Perl programmer 68

3.8 Further reading 69

3.9 Summary 69

4 Perl?s variable types 70

4.1 General concepts 70

Reference counting 71, Looking inside: Devel::Peek 71, The flag system 72

4.2 Scalar variables 74

The SvNULL type 74, SvRV: references 76, SvPV: string values 76, SvPVIV: integers 78, SvPVNV: floating-point numbers 79, SvIV and SvNV 80, SvOOK: offset strings 80

4.3 Magic variables: SvPVMG 81

4.4 Array variables 85

4.5 Hashes 87

4.6 Globs 91

4.7 Namespaces and stashes 94

4.8 Lexical ?my? variables 95

4.9 Code blocks 96

Important CV flags 97

4.10 Further reading 99

4.11 Summary 99

5 The Perl 5 API 100

5.1 Sample entry 101

5.2 SV functions 101

Special SVs 101, Creating SVs 103, Accessing data 110, Manipulating data 119, String functions 124, References 129

5.3 AV functions 132

Creation and destruction 132, Manipulating elements 136, Testing and changing array size 142

5.4 HV functions 144

Creation and destruction 144, Manipulating elements 146

5.5 Miscellaneous functions 150

Memory management 150, Unicode data handling 155, Everything else 158

5.6 Summary 162

6 Advanced XS programming 163

6.1 Pointers and things 164

6.2 Filehandles 166

6.3 Typemaps 167

6.4 The argument stack 169

6.5 C structures 170

C structures as black boxes 170, C structures as objects 176, C structures as hashes 179

6.6 Arrays 183

Passing numeric arrays from Perl to C 183, Passing numeric arrays from C to Perl 190, The Perl Data Language 192, Benchmarks 198, Character strings 199

6.7 Callbacks 202

Immediate callbacks 203, Deferred callbacks 206, Multiple callbacks 207

6.8 Other languages 209

Linking Perl to C++ 209, Linking Perl to Fortran 216, Linking Perl to Java 223

6.9 Interface design: part 2 223

6.10 Older Perls 224

6.11 What?s really going on? 225

What does xsubpp generate? 226

6.12 Further reading 230

6.13 Summary 230

7 Alternatives to XS 231

7.1 The h2xs program 232

7.2 SWIG 233

Data structures 236

7.3 The Inline module 238

What is going on? 239, Additional Inline examples 240, Inline and CPAN 245, Inline module summary 246

7.4 The PDL::PP module 247

The .pd file 248, The Makefile.PL file 249, Pure PDL 251

7.5 Earlier alternatives 251

7.6 Further reading 252

7.7 Summary 253

8 Embedding Perl in C 254

8.1 When to embed 254

8.2 When not to embed 255

8.3 Things to think about 255

8.4 ?Hello C? from Perl 255

Compiling embedded programs 257

8.5 Passing data 257

8.6 Calling Perl routines 259

Stack manipulation 261, Context 263, Trapping errors with eval 263, Calling Perl methods in C 264, Calling Perl statements 265

8.7 Using C in Perl in C 265

8.8 Embedding wisdom 266

8.9 Summary 267

9 Embedding case study 268

9.1 Goals 268

9.2 Preparing the ground 269

9.3 Configuration options 270

9.4 Testing options 273

Binary options 273, Quad-state options 274, String options 275

9.5 Summary 276

10 Introduction to Perl internals 277

10.1 The source tree 277

The Perl library 277, The XS library 278, The I/O subsystem 278, The Regexp engine 278, The parser and tokenizer 278, Variable handling 279, Runtime execution 279

10.2 The parser 279

BNF and parsing 279, Parse actions and token values 281, Parsing some Perl 281

10.3 The tokenizer 282

Basic tokenizing 282, Sublexing 284, Tokenizer summary 285

10.4 Op code trees 285

The basic op 285, The different operations 286, Different flavors of ops 286, Tying it all together 288, PP Code 290, The opcode table and opcodes.pl 293, Scratchpads and targets 293, The optimizer 294, Op code trees summary 294

10.5 Execution 295

10.6 The Perl compiler 295

What is the Perl compiler? 296, B:: modules 296, What B and O provide 299, Using B for simple tasks 300

10.7 Further reading 303

10.8 Summary 303

11 Hacking Perl 304

11.1 The development process 304

Perl versioning 304, The development tracks 305, The perl5-porters mailing list 305, Pumpkins and pumpkings 305, The Perl repository 306

11.2 Debugging aids 306

Debugging modules 307, The built-in debugger: perl -D 307, Debugging functions 310, External debuggers 310

11.3 Creating a patch 317

How to solve problems 317, Autogenerated files 318, The patch itself 319, Documentation 320, Testing 320, Submitting your patch 320

11.4 Perl 6: the future of Perl 321

A history 321, Design and implementation 322, What happens next 323, The future for Perl 5 323

11.5 Further reading 323

11.6 Summary 323

A: Perl?s typemaps 324
B: Further reading 348
C: Perl API index 350
index 355