go 多态

// Sample program to show how polymorphic behavior with interfaces.
package main

import (
    "fmt"
)

// notifier is an interface that defines notification
// type behavior.
type notifier interface {
    notify()
}

// user defines a user in the program.
type user struct {
    name  string
    email string
}

// notify implements the notifier interface with a pointer receiver.
func (u *user) notify() {
    fmt.Printf("Sending user email to %s<%s>\n",
        u.name,
        u.email)
}

// admin defines a admin in the program.
type admin struct {
    name  string
    email string
}

// notify implements the notifier interface with a pointer receiver.
func (a *admin) notify() {
    fmt.Printf("Sending admin email to %s<%s>\n",
        a.name,
        a.email)
}

// main is the entry point for the application.
func main() {
    // Create a user value and pass it to sendNotification.
    bill := user{"Bill", "bill@email.com"}
    sendNotification(&bill)

    // Create an admin value and pass it to sendNotification.
    lisa := admin{"Lisa", "lisa@email.com"}
    sendNotification(&lisa)
}

// sendNotification accepts values that implement the notifier
// interface and sends notifications.
func sendNotification(n notifier) {
    n.notify()
}

Sending user email to Bill<bill@email.com>
Sending admin email to Lisa<lisa@email.com>