我猜是没有办法像Autofac一样做以下事情,为ctor注入一个可枚举的开放泛型类型集合?各种Handle类型都有依赖关系,否则我只是动态构建它们。
class EventOne : IEvent {...}
class EventTwo : IEvent {...}
class EventThree : IEvent {...}
interface IHandleEvent<T> where T : IEvent {...}
class HandleEventOne : IHandleEvent<EventOne> {...}
class HandleEventTwo : IHandleEvent<EventTwo> {...}
class HandleEventThree : IHandleEvent<EventThree> {...}
builder.RegisterAssemblyTypes(myAssembies).AsClosedTypesOf(typeof(IHandleEvent<>));
builder.RegisterType<AService>().As<IAService>();
class AService : IAService
{
public AService(IEnumerable<IHandleEvent<IEvent>> handles)
{...}
}
答案 0 :(得分:9)
正如评论中所解释的那样,你想要的东西是不可能在C#中实现的并且有充分的理由。如果您能够将IHandleEvent<EventOne>
强制转换为IHandleEvent<IEvent>
,那么它也会传入EventTwo
,这会在运行时失败。
所以你需要的是一个中介抽象,它允许获得所有兼容的事件处理程序并调用它们。这种调解员通常被称为IEventPublisher
,可能看起来像这样:
public interface IEventPublisher {
void Publish(IEvent e);
}
您现在可以创建特定于容器的实现。例如,对于Autofac,这将如下所示:
public class AutofacEventPublisher : IEventPublisher {
private readonly IComponentContext container;
public AutofacBusinessRuleValidator(IComponentContext container) {
this.container = container;
}
public void Publish(IEvent e) {
foreach (dynamic handler in this.GetHandlers(e.GetType())) {
handler.Handle((dynamic)e);
}
}
private IEnumerable GetHandlers(Type eventType) =>
(IEnumerable)this.container.Resolve(
typeof(IEnumerable<>).MakeGenericType(
typeof(IHandleEvent<>).MakeGenericType(eventType)));
}
消费者现在可以依赖这种新抽象:
class AService : IAService
{
public AService(IEventPublisher publisher) {...}
}
答案 1 :(得分:0)
您将无法将{
"name": "lib",
"version": "0.0.1",
"main": "lib.js",
"typings": "lib"
}
投射到IHandleEvent<EventThree>
因为IHandleEvent<IEvent>
不是协变,您可以通过添加IHandleEvent<T>
修饰符来添加它。
out
不幸的是, Autofac 不支持协变类型,只支持逆变类型。
顺便说一下,您可以创建自定义public interface IHandleEvent<out TEvent>
where TEvent : IEvent
{ }
实现以获得所请求的行为。像这样:
IRegistrationSource
使用此public class CovariantHandleEventRegistrationSource : IRegistrationSource
{
public bool IsAdapterForIndividualComponents
{
get
{
return false;
}
}
public IEnumerable<IComponentRegistration> RegistrationsFor(Service service,
Func<Service, IEnumerable<IComponentRegistration>> registrationAccessor)
{
IServiceWithType typedService = service as IServiceWithType;
if (typedService == null)
{
yield break;
}
if (typedService.ServiceType.IsGenericType && typedService.ServiceType.GetGenericTypeDefinition() == typeof(IHandleEvent<>))
{
IEnumerable<IComponentRegistration> eventRegistrations = registrationAccessor(new TypedService(typeof(IEvent)));
foreach (IComponentRegistration eventRegistration in eventRegistrations)
{
Type handleEventType = typeof(IHandleEvent<>).MakeGenericType(eventRegistration.Activator.LimitType);
IComponentRegistration handleEventRegistration = RegistrationBuilder.ForDelegate((c, p) => c.Resolve(handleEventType, p))
.As(service)
.CreateRegistration();
yield return handleEventRegistration;
}
}
}
}
,您可以拥有:
IRegistrationSource