Go language dependency injection introduction and application

Dependency injection is a design pattern used to inject objects and their dependencies to improve code testability and flexibility. In Go, dependency injection can be done through: Constructor injection: Passing dependencies when calling the constructor. Setter injection: Define setter methods to set dependencies. Containers: Create and manage dependency containers using third-party libraries or built-in functions.

Introduction and Application of Go Language Dependency Injection

Dependency Injection

Dependency Injection Is a software design pattern for injecting objects and their dependencies. It is the opposite of specifying dependencies when creating a class or method, allowing for code testability and flexibility.

Dependency injection in Go

In Go, dependency injection can be achieved through the following tools:

• Constructor injection : Pass dependencies directly when calling the constructor.
• setter injection: Define a setter method to set dependencies.
• Containers: Create and manage dependency containers using third-party libraries (such as Wire) or built-in functions (Builder).

Practical case: logging

Suppose we have an interface named logger, which has a Log Method:

type logger interface {
    Log(msg string)
}

We have a fileLogger structure that implements the logger interface, which writes log information to a file:

type fileLogger struct {
    path string
}

func (f fileLogger) Log(msg string) {
    // 将日志信息写入文件
}

Now , we create a function to handle the user's request:

func handleRequest(l logger) {
    // 使用 l 记录处理过程中的日志
}

Using constructor injection

We can pass it # directly when calling the handleRequest function ##fileLogger：

func main() {
    // 创建一个 fileLogger
    logger := fileLogger{"log.txt"}

    // 使用 fileLogger 处理请求
    handleRequest(logger)
}

Use setter injection

We can also use setter injection:

func handleRequest(l logger) {
    // 如果 l 不为 nil，则使用 l 记录日志
    if l != nil {
        l.Log("处理请求")
    }
}

func main() {
    // 创建一个 fileLogger
    logger := fileLogger{"log.txt"}

    // 使用 fileLogger 处理请求
    handleRequest(logger)

    // 处理另一个请求时不记录日志
    handleRequest(nil)
}

Use container

Using containers makes it easier to manage dependencies, for example Wire:

func Initialize(logger fileLogger) (*Service, error) {
    // 初始化一个 Service，依赖于 fileLogger
    return &Service{}, nil
}

Then in the

main function:

func main() {
    // 创建一个 Wire 容器
    container, err := wire.Build(Initialize)
    if err != nil {
        log.Fatal(err)
    }

    // 从容器中获取 Service
    service, err := container.Get(new(*Service))
    if err != nil {
        log.Fatal(err)
    }
}

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