Table of Contents

Foreword xxi
Preface xxiii
Acknowledgments xxxi
About the Authors xxxv

Chapter 1: Modules, Packages, and Dependencies 1
Modules 1
Packages 4
Folders, Files, and Organization 6
Importing Packages and Modules 13
Dependencies 16
Summary 25

Chapter 2: Go Language Basics 27
Go Language Overview 27
Numbers 31
Strings 35
UTF-8 37
Variables 40
Constants 48
Naming Identifiers 51
Printing and Formatting 57
Summary 75

Chapter 3: Arrays, Slices, and Iteration 77
List Types: Arrays and Slices 77
How Slices Work 90
Iteration 104
Summary 110

Chapter 4: Maps and Control Structures 111
Maps 111
If Statements 129
Switch Statements 135
Summary 140

Chapter 5: Functions 141
Function Definitions 141
Variadic Arguments 151
Deferring Function Calls 156
Init 162
Summary 166

Chapter 6: Structs, Methods, and Pointers 167
Structs 167
Methods 176
Pointers 182
Nil Receivers 191
Summary 193

Chapter 7: Testing 195
Testing Basics 195
Code Coverage 202
Table Driven Testing 206
Running Tests 213
Test Helpers 222
Summary 229

Chapter 8: Interfaces 231
Concrete Types versus Interfaces 231
Explicit Interface Implementation 233
Implicit Interface Implementation 234
Before Interfaces 235
Using Interfaces 237
Implementing io.Writer 239
Multiple Interfaces 241
Asserting Interface Implementation 241
The Empty Interface 242
Defining Interfaces 243
Embedding Interfaces 249
Type Assertion 250
Assertions through Switch 252
Using Assertions 255
Summary 257

Chapter 9: Errors 259
Errors as Values 259
Panic 264
Don't Panic 273
Custom Errors 289
Wrapping and Unwrapping Errors 294
Errors As/Is 301
Stack Traces 307
Summary 309

Chapter 10: Generics 311
What Are Generics? 311
Summary 334

Chapter 11: Channels 335
Concurrency and Parallelism 335
Go's Concurrency Model 338
Communicating with Channels 342
Unidirectional Channels 351
Closing Channels 352
Buffered Channels 358
Capturing System Signals with Channels 363
Summary 371

Chapter 12: Context 373
The Context Interface 374
Context Rules 380
Context Nodal Hierarchy 381
Context Values 384
Problems with String Keys 388
Securing Context Keys and Values 393
Cancellation Propagation with Contexts 396
Timeouts and Deadlines 405
Context Errors 408
Listening for System Signals with Context 411
Summary 416

Chapter 13: Synchronization 419
Waiting for Goroutines with a WaitGroup 419
Error Management with Error Groups 433
Data Races 443
Synchronizing Access with a Mutex 447
Performing Tasks Only Once 459
Summary 466

Chapter 14: Working with Files 467
Directory Entries and File Information 467
Walking Directories 473
Skipping Directories and Files 477
Creating Directories and Subdirectories 481
File Path Helpers 484
Creating Multiple Directories 489
Creating Files 492
Fixing the Walk Tests 497
Appending to Files 500
Reading Files 503
Beware of Windows 505
The FS Package 506
Using the FS Interface 510
Mocking a File System 513
Embedding Files 517
Summary 522

Index 523

About the Author

Mark Bates is co-founder and instructor at Gopher Guides, the industry leader for Go training, consulting, and conference workshops. Since 2000, he has worked with some of the world's largest, most innovative companies, including Apple, Uber, and Visa. Mark discovered Go in 2013 and has attended GopherCon and hosted their lightning talks. He has spoken at conferences around the world and is a regular on the Go Time podcast.

Cory LaNou, Gopher Guides cofounder and instructor, is a full stack technologist who has specialized in start-ups for the last 20 years. Cory has deep ties to the Go community, having started one of the very first Go meetups in the world, Denver Gophers. Using his real world experience from working on projects such as InfluxDB, a highly scalable database written in Go, he has published numerous practical Go training courses and articles.