Table of Content
1.1 Hello, World 1
1.2 Command-Line Arguments 4
1.3 Finding Duplicate Lines 8
1.4 Animated GIFs 13
1.5 Fetching a URL 15
1.6 Fetching URLs Concurrently 17
1.7 A Web Server 19
1.8 Loose Ends 23
Chapter 2: Program Structure 27
2.1 Names 27
2.2 Declarations 28
2.3 Variables 30
2.4 Assignments 36
2.5 Type Declarations 39
2.6 Packages and Files 41
2.7 Scope 45
Chapter 3: Basic Data Types 51
3.1 Integers 51
3.2 Floating-Point Numbers 56
3.3 Complex Numbers 61
3.4 Booleans 63
3.5 Strings 64
3.6 Constants 75
Chapter 4: Composite Types 81
4.1 Arrays 81
4.2 Slices 84
4.3 Maps 93
4.4 Structs 99
4.5 JSON 107
4.6 Text and HTML Templates 113
Chapter 5: Functions 119
5.1 Function Declarations 119
5.2 Recursion 121
5.3 Multiple Return Values 124
5.4 Errors 127
5.5 Function Values 132
5.6 Anonymous Functions 135
5.7 Variadic Functions 142
5.8 Deferred Function Calls 143
5.9 Panic 148
5.10 Recover 151
Chapter 6:. Methods 155
6.1 Method Declarations 155
6.2 Methods with a Pointer Receiver 158
6.3 Composing Types by Struct Embedding 161
6.4 Method Values and Expressions 164
6.5 Example: Bit Vector Type 165
6.6 Encapsulation 168
Chapter 7: Interfaces 171
7.1 Interfaces as Contracts 171
7.2 Interface Types 174
7.3 Interface Satisfaction 175
7.4 Parsing Flags with flag.Value 179
7.5 Interface Values 181
7.6 Sorting with sort.Interface 186
7.7 The http.Handler Interface 191
7.8 The error Interface 196
7.9 Example: Expression Evaluator 197
7.10 Type Assertions 205
7.11 Discriminating Errors with Type Assertions 206
7.12 Querying Behaviors with Interface Type Assertions 208
7.13 Type Switches 210
7.14 Example: Token-Based XML Decoding 213
7.15 A Few Words of Advice 216
Chapter 8: Goroutines and Channels 217
8.1 Goroutines 217
8.2 Example: Concurrent Clock Server 219
8.3 Example: Concu rent Echo Server 222
8.4 Channels 225
8.5 Looping in Parallel 234
8.6 Example: Concurrent Web Crawler 239
8.7 Multiplexing with select 244
8.8 Example: Concurrent Directory Traversal 247
8.9 Cancellation 251
8.10 Example: Chat Server 253
Chapter 9: Concurrency with Shared Variables 257
9.1 Race Conditions 257
9.2 Mutual Exclusion: sync.Mutex 262
9.3 Read/Write Mutexes: sync.RWMutex 266
9.4 Memory Synchronization 267
9.5 Lazy Initialization: sync.Once 268
9.6 The Race Detector 271
9.7 Example: Concurrent Non-Blocking Cache 272
9.8 Goroutines and Threads 280
Chapter 10: Packages and the Go Tool 283
10.1 Introduction 283
10.2 Import Paths 284
10.3 The Package Declaration 285
10.4 Import Declarations 285
10.5 Blank Imports 286
10.6 Packages and Naming 289
10.7 The Go Tool 290
Chapter 11: Testing 301
11.1 The go test Tool 302
11.2 Test Functions 302
11.3 Coverage 318
11.4 Benchmark Functions 321
11.5 Profiling 323
11.6 Example Functions 326
Chapter 12: Reflection 329
12.1 Why Reflection? 329
12.2 reflect.Type and reflect.Value 330
12.3 Display, a Recursive Value Printer 333
12.4 Example: Encoding S-Expressions 338
12.5 Setting Variables with reflect.Value 341
12.6 Example: Decoding S-Expressions 344
12.7 Accessing Struct Field Tags 348
12.8 Displaying the Methods of a Type 351
12.9 A Word of Caution 352
Chapter 13: Low-Level Programming 353
13.1 unsafe.Sizeof, Alignof, and Offsetof 354
13.2 unsafe.Pointer 356
13.3 Example: Deep Equivalence 358
13.4 Calling C Code with cgo 361