GoLang: The Ultimate Guide

Cover....1

Half Title....2

Title Page....4

Copyright Page....5

Contents....6

Acknowledgments....20

About the Author....22

CHAPTER 1: Crash Course in GoLang....24

IS IT REFERRED TO AS Go OR GoLang?....25

WHAT IS THE PURPOSE OF GoLang?....25

WHY IS Go SO POPULAR?....25

Other Programming Languages vs. Go....26

Python vs. Go....26

But How Does Go Stack Up against Python?....26

SHOULD WE STUDY Go?....27

Go PROGRAMMING FEATURES....27

WHAT MAKES GoLang SUPERIOR TO OTHER COMPUTER LANGUAGES?....28

GoLang’s Core Capability....28

Multithreading and Concurrency....29

From within, Go Empowers Hardware....29

Unmatched Simplicity of Go....30

Built-in Testing and Profiling Framework....30

Easy Learning Curve....30

BEGINNING WITH Go....31

Text Editor....31

Finding a Go Compiler....31

INSTALL Go ON WINDOWS....31

How Can We Know Which Go Language Version Is Preinstalled?....32

Downloading and Installing Go....32

WRITING THE FIRST Go PROGRAM....33

Why Is There a “Go Language”?....34

What Is Missing in Go That the Other Languages Have?....34

Hardware Restrictions....35

The Upsides and Downsides of the Go Language....35

TERMINAL....36

The Open Terminal Tool Window....36

Start the New Session....37

INSTALL Go ON Mac....37

Making Our First Program....39

Implement a Go Program....39

Do Go Programs Interact with Programs Written in C/C++?....40

HOW CAN WE CREATE AN EMPTY FILE IN GoLang?....40

HOW TO MAKE A DIRECTORY IN Go....42

HOW TO READ AND WRITE A Go Program....43

HOW DO WE RENAME AND TRANSFER A FILE IN GoLang?....46

HOW TO READ A FILE LINE BY LINE AND CONVERT IT TO A STRING....47

BASIC SYNTAX....48

Tokens....48

Line Separator....48

Comments....48

Identifiers....49

Keywords....49

Whitespace....50

DATA TYPES IN Go....50

Numbers....51

Booleans....53

Strings....53

VARIABLES IN Go....54

Declaring a Variable....55

Employing the var Keyword....55

Using the Short Variable Declaration....58

CONSTANTS....61

How Should We Declare?....62

Untyped and Typed Numeric Constants....62

Numeric Constant....62

String Literals....64

Boolean Constant....65

VARIABLE SCOPE IN Go....66

Local Variables....66

Global Variables....67

DECLARATION OF MULTIPLE VARIABLES....69

SHORTHAND DECLARATION....71

OPERATORS IN Go....72

Arithmetic Operators....73

Relational Operators....74

Logical Operators....76

Bitwise Operators....76

Assignment Operators....77

Misc Operators....79

CONTROL STATEMENTS....80

if Statement....80

if…else Statement....81

Nested if Statement....83

if..else..if Ladder....84

SWITCH STATEMENT....86

Expression Switch....86

Type Switch....87

ARRAYS....88

Creating and Using an Array....88

Using var Keyword....88

Using a Shorthand Declaration....89

Multidimensional Array....90

How Do You Copy an Array into Another Array?....91

How Can We Pass an Array to a Function?....92

SLICES....93

Slice Declaration....93

Slice Components....94

How Do We Create and Begin a Slice?....95

Using Slice Literal....95

Using an Array....95

Using an Existing Slice....96

Using the make() Function....97

How to Iterate over a Slice....98

Using the for Loop....98

Using Range in a for Loop....99

Using a Blank Identifier in a for Loop....99

Slice Composite Literal....100

How to Sort a Slice of ints....100

Ints....101

IntsAreSorted....101

How Do We Trim a Slice of Bytes in GoLang?....102

How Do We Split a Slice of Bytes?....104

STRING....105

String Literals....106

Using Double Quotes (“”)....106

Using Backticks(“)....106

How Do We Trim a String?....107

Trim....107

TrimLeft....108

TrimRight....109

TrimSpace....110

TrimSuffix....111

TrimPrefix....112

How to Split a String....113

Split....113

SplitAfter....114

SplitAfterN....115

MAPS....116

How Do We Create and Initialize Maps?....117

Simple....117

Using the make() Function....118

WHAT IS A BLANK IDENTIFIER (underscore)?....119

DEFER KEYWORD....120

PANIC IN GoLang....121

RECOVER....122

CLOSURES....123

RECURSION....124

POINTERS....125

What Are Points Used For?....125

Pointers Declaration and Initialization....126

Declaring a Pointer....126

Pointer Initialization....126

Dereferencing a Pointer....127

In GoLang, How Can We Instantiate a Struct Using the New Keyword?....128

Pointers to a Function....129

Create a Pointer and Pass It to the Function....129

Passing an Address of the Variable to Function Call....130

Pointer to a Struct....131

Pointer to Pointer in Go....132

How to Declare a Pointer to a Pointer....132

Comparing Pointers....133

== operator....133

!= operator....134

GoLang STRUCTURES....135

Pointers to a Struct....137

GoLang’s NESTED STRUCTURE....137

GoLang METHODS....138

Method with the Struct Type Receiver....139

Method with the Non-Struct Type Receiver....139

Methods with the Pointer Receiver....140

INTERFACES....141

How Do We Make an Interface?....142

How to Implement Interfaces....142

Why Are Go Interfaces Wonderful?....143

Redundant Functions....143

INHERITANCE....144

POLYMORPHISM USING INTERFACES....146

CHAPTER 2: Test-Driven Development....148

DEVELOPING A NEW PROJECT....149

MAKING Go FILES....149

RUN TESTS....150

A TEST THAT FAILED....150

THE FUNCTION BEING TESTED....152

WRITING A TEST-FIRST FUNCTION....152

REFACTORING Go WITH Go/ANALYSIS....154

Invoke the Refactoring Command....154

Conflicts Resolve....154

Configure the Refactoring Options....154

My Top Four Go Refactoring Approaches....155

Method of Extraction....155

Method of Move....156

Create a Parameter Object....158

Replace Symbolic Constant with Magic Number....159

REFACTORING OUR FIRST Go CODE....160

Include a Parameter Check....161

Add String Formatting....161

Take Out the Code....162

Write a Test....162

GoLang ERROR HANDLING....163

Errors in GoLang....163

Creating Our Own Mistakes....164

Errors Caused by Strings....164

Data Custom Mistakes....165

Handling Errors in Functions....166

Defer....167

Panic....169

Recover....172

Error Wrapping....173

Casting Errors....175

WRITE UNIT TESTING IN Go....176

Beginning....176

Unique to Go....177

Setup and Teardown....178

Testing within the Same Package....179

Five Basic Techniques and Strategies for Developing GoLang Unit Tests....180

CHAPTER 3: Packaging in GoLang....186

PACKAGES IN GoLang....186

Workspace....186

Main Package....187

Import Packages....188

Install Third-Party Packages....188

Init Function....189

Important Considerations....190

Giving the Packages Names....192

Code Exported....193

Essential Go Packages and Libraries....195

Awesome Go....195

GoLang-Set....195

Color....197

Now....198

Gen....199

Gorm....201

Goose....203

Glide....203

Ginkgo....204

Etcd....204

NSQ....205

Docker....207

Kubernetes....207

DEPENDENCY MANAGEMENT....207

Versioning....207

Modules....208

Installing Dependencies....209

Dependencies Must Authenticate....210

Remove Unused Dependencies....210

Installing Dependencies That Are Missing....211

Updating the Versions of Dependencies....211

Listing Dependencies....213

Module vs. Package....213

Naming....213

Fetching Packages....214

CHAPTER 4: Handling Concurrency....216

CONCURRENCY....216

Illustration of the Sleeping Barber Issue....218

Example of a Producer-Consumer Problem....221

Goroutines – CONCURRENCY IN GoLang....224

Go Concurrent Programming....224

Issues with Multithreading....224

How to Create a Goroutine....225

MULTIPLE Goroutines....225

What Is the Difference between Parallelism and Concurrency?....227

Goroutines Provide Several Advantages over Threads....227

COMMUNICATE TO SHARE MEMORY....227

HOW TO USE Goroutines TO ACCESS SHARED RESOURCES....230

Access Shared Resources Using Goroutines....230

Using Mutual Exclusion to Get Access to Shared Resources....230

Using Atomic Counters to Get Access to Shared Resources....232

Concurrency Issues....233

Concurrency Disadvantages....234

Benefits of Concurrency....234

Problems with Concurrency....234

CHAPTER 5: GoLang for JavaScript Developers....236

FLOW CONTROL....236

Loop Control Statements in Go....242

Break Statement....243

Goto Statement....243

Continue Statement....244

TYPES....245

Basic Types....245

Numbers....245

Booleans....247

Strings....248

Type Conversion....249

Type Assertion....249

Structs....251

Initializing....253

Composition vs. Inheritance....253

HOW DO YOU MAKE MODULES IN GoLang?....258

Adding Dependencies to the Go Module....260

PACKAGE MANAGEMENT USING Go MODULES....260

What Exactly Is the Go Module?....261

Starting Out....262

Module Initializing....262

Setting Up Dependencies....262

Eliminating Unnecessary Dependencies....262

Updating a Dependency Version....263

ERROR HANDLING....263

Error Type Representation....264

Various Approaches to Getting More Information from an Error....265

Don’t Ignore Errors....269

IN GoLang, THERE ARE SEVERAL TECHNIQUES TO COMPARE STRINGS....270

Making Use of Comparison Operators....270

Using the Compare() Method....272

FUNCTIONS IN Go....273

Function Declaration....273

Function Calling....274

Function Arguments....275

FUNCTION RETURNING MULTIPLE VALUES....276

Giving Names to the Return Values....277

VARIADIC FUNCTIONS....278

ANONYMOUS FUNCTION....279

GoLang main AND init FUNCTIONS....279

main() Function....280

init() Function....280

CHAPTER 6: Code Optimization....282

A PATTERN FOR OPTIMIZING Go....282

Why Is Code Optimization Necessary?....290

Code Base That Is Cleaner....291

Improved Consistency....291

Pages That Load Faster....291

Improved Code Readability....292

More Efficient Refactoring....292

Easier to Understand Debugging....292

Enhanced Workflow....292

Code Upkeep Is Now Easier....293

Improved Feature Development....293

The Ultimate Guide to GoLang Performance Optimization....293

GoLang Performance Hints That Have Been Proven and Tested....293

Optimization of Resource Efficiency....293

Optimization of Latency in GoLang....294

Efficiency of Algorithms....294

Patterns of GoLang Application Performance....294

Use Goroutines Sparingly....294

CPU Work Should Parallelize....295

Asynchronous I/O Operations....295

Keep an Eye on Our Timeouts....295

Memory Should Not Allocate in Hot Spots....295

Make Use of Lock-Free Algorithms....295

Prefer Read-Only Locks....295

Reduce or Eliminate the Use of ‘cgo’....295

Make Use of Buffered I/O....296

Use Binary Instead....296

StringBuffer and StringBuilder Are Preferable....296

Make Use of Regular Expressions....296

Slices Should Preallocate....296

Select Protocol Buffers and MessagePack as Our Options....296

For Maps, Use int Rather Than a String....296

GoLang FOR SECURE CODING....296

Stuck in a Rut with Manual Security....296

With Go, There Is a Need for Integrated, Automated Security....297

How Does Instrument-Based Security Work in the Go Pipeline?....298

Contrast Goes Above and Beyond with Modern Application Security....299

Go Security Best Practices....299

Verify the Input Entries....300

Make Use of HTML Templates....301

Protect Ourselves against SQL Injections....301

Encrypt Any Sensitive Data....302

Make HTTPS Communication Mandatory....303

Be Cautious of Mistakes and Logs....305

BEST PRACTICES FOR GoLang....306

Syntax....307

Assign Datatypes to Newly Created Variables....307

Do Not Declare a Variable or Import a Package That We Do Not Require....307

Follow Proper Naming Conventions....307

Make Use of Comments to Help in Knowledge Transfer....308

Simple, Readable, and Maintainable Code....308

Avoid Nesting by Dealing with Mistakes First....308

Avoid Utility Repeats....308

To Address Exceptional Circumstances, Use the Type Switch....308

Go Code Organization....309

For Use in CI/CD Workflows....309

Make Use of Go Modules....309

Ensure Immutability and Availability Using GOPROXY....310

CHAPTER 7: GoLang Tutorials and Projects....312

WEB APPLICATION TO GENERATE QR CODE IN GoLang....312

Install the Necessary Package....313

Development....313

Main.go Source Code....313

Generator.html Source Code....314

Implementation....314

SETTING UP THE Go HTTP CLIENT....314

HTTP Client in GoLang....315

POST and GET Requests....316

Adding Request Headers....317

Our Requests Are Being Authorized....319

WHAT IS THE GoLang REST API?....320

Using GoLang to Consume a REST API....322

Project Setup....322

Imports....322

Example of a Response....323

Struct....323

Code....323

Run the Project....324

APPRAISAL....326

CHEAT SHEET....342

BIBLIOGRAPHY....352

INDEX....356

Go, also known as GoLang, is a Google-developed open-source, compiled, and statically typed computer language. Go is a general purpose programming language with a straightforward syntax and a large standard library. The building of highly accessible and scalable web apps is one of the primary areas where GoLang is widely used. It may also be used to develop command-line programs, desktop applications, and even mobile apps.

Go was designed from the ground up for networking and infrastructure-related applications. It was developed as a replacement for popular server-side languages like Java and C++. The Go programming language aims to combine the efficiency and safety of a statically typed, compiled language with the simplicity of programming of an interpreted, dynamically typed language. It also aspires to be cutting edge, with networked and multicore computer capabilities.

Why Should You Learn GoLang?

GoLang is becoming one of the most popular languages, which means that learning it can open up new doors of opportunity and even help you land a job at various companies that use Go extensively.

 Ease of writing concurrent programs, fast compilation, simple syntax, and static linking are some of the features that make Go an ideal candidate for developing various applications.

This Book Includes:

• A step-by-step approach to problem solving and skill development
• A quick run-through of the basic concepts, in the form of a "Crash Course"
• Advanced, hands-on core concepts, with a focus on real-world problems
• Industry-level coding paradigms, and a practice-oriented explanatory approach
• Special emphasis on writing clean and optimized code, with additional chapters focused on coding methodology