我可以说这个scala代码是依赖注入的吗?
我读过一些关于Scala蛋糕模式的文章,基本上理解了它。以下是我从本文中复制的一些示例代码: 组成部分:我可以说这个scala代码是依赖注入的吗?,scala,dependency-injection,cake-pattern,Scala,Dependency Injection,Cake Pattern,我读过一些关于Scala蛋糕模式的文章,基本上理解了它。以下是我从本文中复制的一些示例代码: 组成部分: case class User(username:String, password: String) trait UserRepositoryComponent { val userRepository: UserRepository class UserRepository { def authenticate(user: User): User = {
case class User(username:String, password: String)
trait UserRepositoryComponent {
val userRepository: UserRepository
class UserRepository {
def authenticate(user: User): User = {
println("authenticating user: " + user)
user
}
def create(user: User) = println("creating user: " + user)
def delete(user: User) = println("deleting user: " + user)
}
}
trait UserServiceComponent { this: UserRepositoryComponent =>
val userService: UserService
class UserService {
def authenticate(username: String, password: String): User =
userRepository.authenticate(User(username, password))
def create(username: String, password: String) =
userRepository.create(new User(username, password))
def delete(user: User) =
userRepository.delete(user)
}
}
要组合它们的对象:
object ComponentRegistry extends
UserServiceComponent with
UserRepositoryComponent {
val userRepository = new UserRepository
val userService = new UserService
}
object TestingComponentRegistry extends
UserServiceComponent with
UserRepositoryComponent {
val userRepository = mock[UserRepository]
val userService = mock[UserService]
}
object Application {
val userService = new UserService(new UserRepository)
}
object Test {
val userService = new UserService(mock[UserRepository])
}
如果我在一个简单的项目中,我想让它变得更简单。代码如下所示:
case class User(username:String, password: String)
class UserRepository {
def authenticate(user: User): User = {
println("authenticating user: " + user)
user
}
def create(user: User) = println("creating user: " + user)
def delete(user: User) = println("deleting user: " + user)
}
class UserService(userRepository: UserRepository) {
def authenticate(username: String, password: String): User =
userRepository.authenticate(User(username, password))
def create(username: String, password: String) =
userRepository.create(new User(username, password))
def delete(user: User) =
userRepository.delete(user)
}
将它们结合起来:
object ComponentRegistry extends
UserServiceComponent with
UserRepositoryComponent {
val userRepository = new UserRepository
val userService = new UserService
}
object TestingComponentRegistry extends
UserServiceComponent with
UserRepositoryComponent {
val userRepository = mock[UserRepository]
val userService = mock[UserService]
}
object Application {
val userService = new UserService(new UserRepository)
}
object Test {
val userService = new UserService(mock[UserRepository])
}
我的问题是,我的代码是否仍然可以被视为“依赖注入”
UserService
的构造函数中声明了依赖项UserService
接收它应该用作构造函数参数的组件,而不是在UserService
中直接实例化UserRepository
IMHO,您的代码正是DI 90%以上的时候应该使用的代码。不需要像Spring或Guice这样的“花哨”框架,不需要像cake模式这样的“花哨”设计模式,只需在构造函数中注入依赖项即可。完成、干净、易于测试、易于更换不同的实现(*)
(*):请注意,在您的示例中,要实现这一点,
UserRepository
可能应该是一个特性,而不是一个类。我非常喜欢您的答案:)这就是蛋糕模式,经常使用它的是所谓的“依赖注入”,从这个角度来看,它可以被视为“组件化”的特例由蛋糕促进的软件。