Example dependencies injection with dig

main.go

package main

import (
	"fmt"
	"go.uber.org/dig"
)

type Say struct {
	Name string
}

func (s Say) Hello() {
	fmt.Println("HELLO ", s.Name)
}

type Eat struct {
	Meal string
}

func (e Eat) Diner() {
	fmt.Println(e.Meal, "!!!")
}

type Hoooman struct {
	dig.In
	Say *Say
	Eat *Eat
}

func main() {
	c := dig.New()
	// Provide a Config object. This can fail to decode.
	err := c.Provide(func() (*Say, error) {
		return &Say{Name: "Dzung"}, nil
	})
	if err != nil {
		panic(err)
	}

	// Provide a way to build the logger based on the configuration.
	err = c.Provide(func() (*Eat, error) {
		return &Eat{Meal: "Pizza"}, nil
	})
	if err != nil {
		panic(err)
	}

	// Invoke a function that requires the injected object
	err = c.Invoke(func(e *Eat, s *Say) {
		s.Hello()
		e.Diner()
	})
	if err != nil {
		panic(err)
	}


	var hoo *Hoooman
	// Invoke with Parameter Objects
	err = c.Invoke(func(h Hoooman) {
		hoo = &h
	})
	if err != nil {
		panic(err)
	}

	hoo.Say.Hello()
	hoo.Eat.Diner()
}