Why the Go interface does not necessarily accept value types (but does accept pointer types)

Conclusion: the value does not guarantee that the address will be retrieved

Either s = &serviceImpl {} or s = &serviceImpl {} will work

type Service interface {
   Login(username, password string) string
}

type ServiceImpl struct{}

func (s ServiceImpl) Login(username, password string) string {
   return username + password
}

func main(a) {
   var s Service
   s = ServiceImpl{} 
   // s = &ServiceImpl{}
   fmt.Println(s.Login("abc"."123"))}Copy the code

But if we change the receiver of ServiceImpl to a pointer type, the interface must be assigned a pointer type:

type Service interface {
   Login(username, password string) string
}

type ServiceImpl struct{}

func (s *ServiceImpl) Login(username, password string) string {
   return username + password
}

func main(a) {
   var s Service
   s = &ServiceImpl{}
   fmt.Println(s.Login("abc"."123"))}Copy the code

There is no way to get an address for a type like the following:

type Time int

func main(a) {
   fmt.Println(&Time(1))}Copy the code

Sure, you can get the address like this:

type Time int

func main(a) {
   t := Time(1)
   fmt.Println(&t)
}
Copy the code