ios - 如何在我的工厂解析器中注册 2 个具有相同抽象接口(interface)的依赖项？

Question

我有一个依赖容器，看起来像这样 -

public protocol DependencyContainer {
  typealias FactoryClosure = (Self) -> AnyObject
  func register<Service>(type: Service.Type, closure: @escaping FactoryClosure)
  func resolve<Service>(type: Service.Type) -> Service
}

public final class CoreDependencyContainer: DependencyContainer {

  private var services: Dictionary<ObjectIdentifier, FactoryClosure> = [:]

  public func register<Service>(type: Service.Type, closure: @escaping FactoryClosure) {
    services[ObjectIdentifier(type)] = closure
  }

  public func resolve<Service>(type: Service.Type) -> Service {
    if let service = services[ObjectIdentifier(type)]?(self) as? Service {
      return service
    }
    preconditionFailure("Could not resolve service for \(type)")
  }

}

我有一些服务注册如下:

dependencies.register(type: RemoteImageDataLoader.self, closure: { container in
  let httpClient = container.resolve(type: HTTPClient.self)
    return RemoteImageDataLoader(client: httpClient)
})

但是，我想注册 2 个符合抽象类型 RemoteImageDataLoader 的服务.

dependencies.register(type: RemoteImageDataLoader.self, closure: { container in
  let httpClient = container.resolve(type: HTTPClient.self)
    return RemoteImageDataLoader(client: httpClient)
})

dependencies.register(type: RemoteImageDataLoader.self, closure: { container in
  let httpClient = container.resolve(type: AuthenticatedHTTPClient.self)
    return RemoteImageDataLoader(client: httpClient)
})

这显然不起作用，因为第二个条目将替换 services 中的第一个条目字典。

我试图创建一个 typealias改为使用，但这不起作用。

dependencies.register(type: RemoteImageDataLoader.self, closure: { container in
  let httpClient = container.resolve(type: HTTPClient.self)
    return RemoteImageDataLoader(client: httpClient)
})

typealias AuthRemoteImageLoader = RemoteImageDataLoader

dependencies.register(type: AuthRemoteImageLoader.self, closure: { container in
  let httpClient = container.resolve(type: AuthenticatedHTTPClient.self)
    return RemoteImageDataLoader(client: httpClient)
})

在这种情况下如何注册第二个依赖项？

我想避免创建两个版本的 RemoteImageDataLoader因为唯一的区别是注入(inject)的 HTTPClient实例。

Answer 1

当您使用 ObjectIdentifier 时，它不能在当前工作作为字典中的键，typealias不改变。

您基本上是两次注册同一个对象。

创建一个符合相同接口(interface)的空协议(protocol)。您还需要扩展您以符合新的空接口(interface)，否则您的 resolve方法将抛出 preconditionFailure

protocol AuthRemoteImageLoader: RemoteImageDataLoader { }
extension RemoteImageDataLoader: AuthRemoteImageLoader { }

您也可以考虑使用泛型来指定 HTTPClient正在使用的接口(interface)，并扩展RemoteImageDataLoader根据客户的类型采取相应的行动。