无法将对象添加到列表

我在试一个使用 Domain Events 通知系统中发生了什么事情(从 here 和 here ).

我真的很接近让代码按我想要的方式工作,但是,我碰到了一个砖墙位。这是我的 DomainEvents 班级:

 public static class DomainEvents
    {
        [ThreadStatic]
        private static IList<IEventHandler<IDomainEvent>> Actions;

        public static void Register<T>(IEventHandler<T> callback) where T : IDomainEvent
        {
            if (Actions == null)
            {
                Actions = new List<IEventHandler<IDomainEvent>>();
            }

            Actions.Add(callback); // <---- Problem here, since I can't add callback to the collection.
        }

        public static void ClearCallbacks()
        {
            Actions = null;
        }

        public static void Raise<T>(T args) where T : IDomainEvent
        {
            if (Actions == null)
            {
                return;
            }

            foreach (var action in Actions)
            {
                if (action is IEventHandler<T>)
                {
                    ((IEventHandler<T>)action).Handle(args);
                }
            }
        }

以上内容无法编译,因为 Actions.Add callback 因为这是一个 IEventHandler<T> 键入而不是a IEventHandler<IDomainEvent> 类型。这里还有一些代码需要澄清。

这是从我的控制台应用程序调用的:

DomainEvents.Register(new CustomerHasUnpaidDuesEventHandler());

CustomerHasUnpaidDuesEventHandler 工具 IEventHandler<CustomerHasUnpaidDuesEvent> ,在哪里 CustomerHasUnpaidDuesEvent IDomainEvent

public class CustomerHasUnpaidDuesEventHandler : IEventHandler<CustomerHasUnpaidDuesEvent>
    {
        public IEmailSender EmailSender { get; set; }

        public void Handle(CustomerHasUnpaidDuesEvent @event)
        {
            this.EmailSender.SendEmail(@event.Customer.EmailAddress);
        }
    }

public class CustomerHasUnpaidDuesEvent : IDomainEvent
    {
        public CustomerHasUnpaidDuesEvent(Customer customer)
        {
            this.Customer = customer;
        }

        public Customer Customer { get; set; }
    }

这就是我不明白的-如果 客户支付 IDomain事件 ,那为什么打电话给 操作。添加 弱点?我如何解决这个问题?

编辑:

为了让事情更清楚,下面是我的测试应用程序的完整代码:

    class Program
    {
        static void Main()
        {
            DomainEvents.Register(new CustomerHasUnpaidDuesEventHandler());

            var c = new Customer();

            c.EmailAddress = "test@dfsdf.com";

            c.CheckUnpaidDues();
        }
    }


 public interface IEventHandler<in T> where T : IDomainEvent
    {
        void Handle(T args);
    }

 public interface IEmailSender
    {
        void SendEmail(string emailAddress);
    }


 public interface IDomainEvent
    {
    }

public static class DomainEvents
    {
        [ThreadStatic]
        private static IList<IEventHandler<IDomainEvent>> Actions;

        public static void Register<T>(IEventHandler<T> callback) where T: IDomainEvent
        {
            if (Actions == null)
            {
                Actions = new List<IEventHandler<IDomainEvent>>();
            }

            Actions.Add(callback);
        }

        public static void ClearCallbacks()
        {
            Actions = null;
        }

        public static void Raise<T>(T args) where T : IDomainEvent
        {
            if (Actions == null)
            {
                return;
            }

            foreach (IEventHandler<T> action in Actions)
            {
                (action).Handle(args);
            }
        }
    }


public class CustomerHasUnpaidDuesEventHandler : IEventHandler<CustomerHasUnpaidDuesEvent>
    {
        public IEmailSender EmailSender { get; set; }

        public void Handle(CustomerHasUnpaidDuesEvent @event)
        {
            this.EmailSender.SendEmail(@event.Customer.EmailAddress);
        }
    }

public class CustomerHasUnpaidDuesEvent : IDomainEvent
    {
        public CustomerHasUnpaidDuesEvent(Customer customer)
        {
            this.Customer = customer;
        }

        public Customer Customer { get; set; }
    }

public class Customer
    {
        public string Name { get; set; }

        public string EmailAddress { get; set; }

        public bool HasUnpaidDues { get; set; }

        public void CheckUnpaidDues()
        {
            HasUnpaidDues = true;
            DomainEvents.Raise(new CustomerHasUnpaidDuesEvent(this));
        }
    }

干杯。