// staticchecking/petspeak.go

// (c)2017 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

package main

import "fmt"

type Cat struct {}

func (this Cat) speak() { fmt.Printf("meow!\n")}

type Dog struct {}

func (this Dog) speak() { fmt.Printf("woof!\n")}

type Bob struct {}

func (this Bob) bow() {

fmt.Printf("thank you, thank you!\n")

}

func (this Bob) speak() {

fmt.Printf("Welcome to the neighborhood!\n")

}

func (this Bob) drive() {

fmt.Printf("beep, beep!\n")

}

type Speaker interface {

speak()

}

func command(s Speaker) { s.speak() }

// If "Speaker" is never used

// anywhere else, it can be anonymous:

func command2(s interface { speak() }) { s.speak() }

func main() {

command(Cat{})

command(Dog{})

command(Bob{})

command2(Cat{})

command2(Dog{})

command2(Bob{})

}

/* Output:

meow!

woof!

Welcome to the neighborhood!

meow!

woof!

Welcome to the neighborhood!

*/