a sample of dependency injection in golang

dependency_injection.go

package main

import (
	"encoding/json"
	"log"
	"net/http"
)

// hashtag framework
type injectionContainer interface {
	GetDep(name string) interface{}
}
type handler func(w http.ResponseWriter, r *http.Request) (int, http.Header, []byte)
type controller func(r *http.Request) (int, http.Header, []byte)
type injectable func(container injectionContainer) controller

func (c controller) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	code, headers, body := c(r)
	for key, vals := range headers {
		for _, val := range vals {
			w.Header().Set(key, val)
		}
	}
	w.WriteHeader(code)
	w.Write(body)
}

// A default dependency injection container
type container map[string]interface{}

func (c container) GetDep(name string) interface{} {
	return c[name]
}

// application code
type repo interface {
	FindAll() []string
}

type movieRepo struct {
}

func (r *movieRepo) FindAll() []string {
	return []string{}
}

func movieController(repo *movieRepo) controller {
	return func(r *http.Request) (int, http.Header, []byte) {
		movies := repo.FindAll()
		body, _ := json.Marshal(movies)
		return 200, http.Header{}, []byte(body)
	}
}

func buildMovieController(container injectionContainer) http.Handler {
	movieRepo := container.GetDep("movieRepo").(*movieRepo)
	return http.Handler(movieController(movieRepo))
}

func main() {
	c := injectionContainer(container{
		"movieRepo": &movieRepo{},
	})
	http.Handle("/foo", buildMovieController(c))
	log.Fatal(http.ListenAndServe(":8080", nil))
}