如何将对象投射到Action< T>

本文介绍了如何将对象投射到Action< T>的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我已经创建了一个简单的消息总线，它可以排队并发出/发布事件.

I've created a simple message bus that queues and emits/publishes events.

我正在使用StructureMap定位事件的注册处理程序( Action< T> )，但不确定如何将其从StructureMap返回的对象强制转换为可调用的操作.

I'm using StructureMap to locate the registered handlers (Action<T>) of the event but am not sure how to cast it from the object that StructureMap returns into an invoke-able action.

因为我无法转换为 Action< object> ，所以我假设 Action< T> 不是协变的?可以用另一种方式吗?

Since I can't cast to Action<object> I'm assuming that Action<T> is not covariant? Can this be done another way?

public class Bus { private ConcurrentQueue<object> events = new ConcurrentQueue<object>(); public void Queue<TEvent>(TEvent e) { events.Enqueue(e); } public void Emit() { object e; while (events.TryDequeue(out e)) { var handlerType = typeof(Action<>).MakeGenericType(e.GetType()); foreach (var handler in ObjectFactory.GetAllInstances(handlerType)) { // how to invoke action? } } } }

推荐答案

如果在您的 Queue 方法内部，您不将事件排队，而是将发出事件的代码排队?

What if inside your Queue method you'd queue not events but rather the code which emits them?

private ConcurrentQueue<Action> handlers = new ConcurrentQueue<Action>(); public void Queue<TEvent>(TEvent e) { handlers.Enqueue(new Action(() => { foreach (var handler in GetHandlers<TEvent>()) { handler(e); } })); } public void Emit() { Action act; while (handlers.TryDequeue(out act)) { act(); } } private IEnumerable<Action<TEvent>> GetHandlers<TEvent>() { return ObjectFactory.GetAllInstances(typeof(Action<TEvent>>)); }

希望这会有所帮助.