如何用Golang实现组合对象结构_Golang 组合模式对象结构实践

type Logger struct{}

func (l *Logger) Log(msg string) {
    fmt.Println("Log:", msg)
}

type UserService struct {
    Logger // 匿名嵌入
    DB     *sql.DB
}

type OrderService struct {
    Logger // 同样复用
    Cache  *redis.Client
}

userSvc := &UserService{DB: db}
userSvc.Log("User created") // 直接调用嵌入的方法

type Notifier interface {
    Notify(message string) error
}

type EmailService struct{}

func (e *EmailService) Notify(message string) error {
    fmt.Println("Sending email:", message)
    return nil
}

type AlertService struct {
    Notifier // 嵌入接口
}

func (a *AlertService) Trigger(alert string) {
    a.Notify("ALERT: " + alert)
}

emailer := &EmailService{}
alert := &AlertService{Notifier: emailer}
alert.Trigger("High CPU usage")

type Context struct {
    Request *http.Request
    Writer  http.ResponseWriter
}

type AuthModule struct{}
func (a *AuthModule) Check() bool { return true }

type LoggerModule struct{}
func (l *LoggerModule) LogAccess() { fmt.Println("Access logged") }

type Handler struct {
    Context
    AuthModule
    LoggerModule
}

func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    h.Context = Context{r, w}
    if h.Check() {
        h.LogAccess()
        w.Write([]byte("OK"))
    } else {
        w.WriteHeader(403)
    }
}