dip1.go

package main

type Repository interface {
    Find(id int) (interface{}, error)
    Save(data interface{}) error
}

type User struct {
    ID   int
    Name string
}

type UserRepository struct {}

func (r UserRepository) Find(id int) (interface{}, error) {
    return User{ID: id, Name: "John Doe"}, nil
}

func (r UserRepository) Save(data interface{}) error {
    user := data.(User)
    fmt.Printf("Saving user %d: %s\n", user.ID, user.Name)
    return nil
}

type Service struct {
    repository Repository
}

func (s Service) FindUser(id int) (interface{}, error) {
    return s.repository.Find(id)
}

func (s Service) SaveUser(user User) error {
    return s.repository.Save(user)
}

func main() {
    userRepository := UserRepository{}
    service := Service{repository: userRepository}

    user, _ := service.FindUser(1)
    fmt.Println(user) // User{ID: 1, Name: "John Doe"}

    service.SaveUser(User{ID: 1, Name: "Jane Smith"}) // Saving user 1: Jane Smith
}