基于接口实现Go多态

package main

import "fmt"

type User struct {
    Name string
    Email string
    Notifier userNotifier
}

func (u *User)notifier(message string) error {
    return u.Notifier.sendMessage(u, message)
}

type userNotifier interface {
    sendMessage(u *User, message string) error
}

type emailNotifier struct {}

func (e emailNotifier)sendMessage(u *User, message string) error  {
    _, err := fmt.Printf("send email to %s with content %s\n", u.Name, message)
    return err
}

type smsNotifier struct {}

func (s smsNotifier) sendMessage(u *User, message string) error {
    _, err := fmt.Printf("send sms to %s with content %s\n", u.Name, message)
    return err
}



func main() {
    user1 := User{
        Name:     "sss",
        Email:    "sss@qq.com",
        Notifier: emailNotifier{},
    }
    user2 := User{
        Name:     "xxx",
        Email:    "xxx@qq.com",
        Notifier: smsNotifier{},
    }
    user1.notifier("hello")
    user2.notifier("world")
}