Golang generics - go

Question

trying to create auth service that is abstract by using generic type. I wanted to create package Auth that will have New() method for initialization but currently facing the issue that I can resolve. Anyone have idea if this is even possible and if this is even go way of solving the issue?
type Register[T any] interface {
SignUp(T) (*AuthEntity, error)
}
type AuthEntity struct {
ID string
UpdatedAt time.Time
CreatedAt time.Time
}
type AuthService[T any] struct {
Register[T]
}
type PasswordStrategy struct{}
type SignUpViaPassword struct {
Email string
Password string
}
func (s PasswordStrategy) SignUp(signUpData SignUpViaPassword) (*AuthEntity, error) {
return &AuthEntity{ID: "email#gmail.com"}, nil
}
func New[T any](register Register[T]) AuthService[T] {
return AuthService[T]{
Register: register,
}
}
type GoogleStrategy struct{}
type SignUpViaGoogle struct {
Token string
}
func (s GoogleStrategy) SignUp(signUpData SignUpViaGoogle) (*AuthEntity, error) {
return &AuthEntity{}, nil
}
func main() {
// This works as expected
authService := AuthService[SignUpViaPassword]{
Register: PasswordStrategy{},
}
entity, err := authService.SignUp(SignUpViaPassword{Password: "Kako ide", Email: "email#gmail.com"})
if err != nil {
log.Println(err)
}
log.Println(entity)
// This also works as expected
googleAuthService := AuthService[SignUpViaGoogle]{
Register: GoogleStrategy{},
}
entity2, err := authService.SignUp(SignUpViaPassword{Password: "Kako ide", Email: "email#gmail.com"})
if err != nil {
log.Println(err)
}
log.Println(entity2)
// this doesn't work and returns error type PasswordStrategy of PasswordStrategy{} does not match Register[T] (cannot infer T)
New(PasswordStrategy{})
New(GoogleStrategy{})
}

Answer 1

It cannot infer what T should be, so you can explicitly specify it:
New[SignUpViaPassword](PasswordStrategy{})