design model 之 subcribe/publish

type sayer interface {
    say()
}

type man struct{

}

func (m *man)(){
    fmt.Printf("I am man")
}

type woman struct{

}

func (w *woman)(){
    fmt.Printf("I am woman")
}

func factory(t string) sayer{
    if t=="man" {
        return &man{}
    }else{
        return &woman{}
    }
}

func main(){
    s := factory("man")
    s.say()
}