test1.go

package main

type animal interface {
	say()
	work()
}

type dog struct {
}

type cat struct {
}

func (self dog) say() {
	println("i am a dog")
}

func (self *dog) work() {
	println("dog is working")
}

func (self cat) say() {
	println("i am a cat")
}

func (self *cat) work() {
	println("cat is working")
}

func main() {
	d := new(dog)
	d.say()
	d.work()
	d1 := *d
	d1.say()
	d1.work()

	c := new(cat)
	c.say()
	c.work()
	c1 := *c
	c1.say()
	c1.work()

	println("=================")
	doit(d)
	// doit(d1)
	println(">>>>>>>>>>>>>>>>>>")
	doit(c)
}

func doit(a animal) {
	a.say()
	a.work()
}