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)

DI induced damage

DI induced damage results from situations where the use of DI makes the code harder to understand, maintain, or otherwise use.

A long constructor parameter list

A long constructor parameter list is perhaps the most common and most often complained about code damage caused by DI. While DI is not the root cause of code damage, it certainly doesn't help. 

Consider the following example, which uses constructor injection:

func NewMyHandler(logger Logger, stats Instrumentation,
parser Parser, formatter Formatter,
limiter RateLimiter,
cache Cache, db Datastore) *MyHandler {

return &MyHandler{
// code removed
}
}

// MyHandler does something fantastic
type MyHandler struct {
// code removed...