Book Image

Hands-On Dependency Injection in Go

By : Corey Scott
Book Image

Hands-On Dependency Injection in Go

By: Corey Scott

Overview of this book

Hands-On Dependency Injection in Go takes you on a journey, teaching you about refactoring existing code to adopt dependency injection (DI) using various methods available in Go. Of the six methods introduced in this book, some are conventional, such as constructor or method injection, and some unconventional, such as just-in-time or config injection. Each method is explained in detail, focusing on their strengths and weaknesses, and is followed with a step-by-step example of how to apply it. With plenty of examples, you will learn how to leverage DI to transform code into something simple and flexible. You will also discover how to generate and leverage the dependency graph to spot and eliminate issues. Throughout the book, you will learn to leverage DI in combination with test stubs and mocks to test otherwise tricky or impossible scenarios. Hands-On Dependency Injection in Go takes a pragmatic approach and focuses heavily on the code, user experience, and how to achieve long-term benefits through incremental changes. By the end of this book, you will have produced clean code that’s easy to test.
Table of Contents (15 chapters)

Advantages of constructor injection

For many programmers and programming languages, constructor injection is their default method for DI. It is perhaps no surprise therefore that it has numerous advantages.

Separation from the dependency life cycle—Constructor injection, like most DI methods, separates the life cycle management of the dependency from the object that it's being injected into. By doing this, the object becomes more straightforward and easier to understand.

Easy to implement—As we saw in our previous examples, it's easy to take this:

// WelcomeSender sends a Welcome email to new users
type WelcomeSender struct {
Mailer *Mailer

func (w *WelcomeSender) Send(to string) error {
body := w.buildMessage()

return w.Mailer.Send(to, body)

And change it to this:

func NewWelcomeSender(mailer *Mailer) *WelcomeSender {
return &WelcomeSender...