考虑下面的接口和类声明。如何创建从实现接口的基类派生的实例列表?
public interface IMessage
{
string Body { get; set; }
}
public abstract class MessageBase : IMessage
{
public string Body { get; set; }
}
public class MessageA : MessageBase { }
public class MessageB : MessageBase { }
public class MessageC : MessageBase { }
public interface IMessageProcessor<T> where T : IMessage
{
Action<T> ProcessorAction { get; set; }
}
public abstract class MessageProcessorBase<T> : IMessageProcessor<T> where T : MessageBase
{
public Action<T> ProcessorAction { get; set; }
}
public class MessageAProcessor : MessageProcessorBase<MessageA> { }
public class MessageBProcessor : MessageProcessorBase<MessageB> { }
public class MessageCProcessor : MessageProcessorBase<MessageC> { }
现在我要声明,像这样的处理器实例列表,但无法弄清楚什么泛型类型可以让我的任何派生处理器类型添加到列表中。
var processors = new List<???>();
processors.Add(new MessageAProcessor());
processors.Add(new MessageBProcessor());
processors.Add(new MessageCProcessor());
我曾尝试:
// compiles but throws InvalidCastException
var processors = new List<IMessageProcessor<IMessage>>();
processors.Add((IMessageProcessor<IMessage>)new MessageAProcessor());
和
// compiles but throws InvalidCastException
var processors = new List<IMessageProcessor<MessageBase>>();
processors.Add((IMessageProcessor<MessageBase>)new MessageAProcessor());
和
// won't compile
var processors = new List<MessageProcessorBase<MessageBase>>();
processors.Add((MessageProcessorBase<MessageBase>)new MessageAProcessor());
我应该这个列表的类型是什么?我知道我必须在这里错过一些明显的东西。任何帮助在这里将不胜感激。谢谢!
您可以将'ProcessMessage'实现移至基址:'var msg = message as T' –
@AlekseyL。好点,修正了,谢谢 – 3615
@ 3615谢谢 - 现在我明白了。 –