我正在使用MVVM和Microsoft Prism库来开发
WPF项目.所以,当我需要通过类进行通信时,我使用类Microsoft.Practices.Prism.MefExtensions.Events.MefEventAggregator,我发布事件和订阅方法如下:
要发布:
myEventAggregator.GetEvent< MyEvent>()出版(myParams)
认购:
myEventAggregator.GetEvent< MyEvent>()订阅(MySubscribedMethod).
解决方法
据我所知,如果所有事件订阅者都使用ThreadOption.PublisherThread选项(这也是默认选项),则事件是同步执行的,订阅者可以修改EventArgs对象,因此您可以在发布者中使用
myEventAggregator.GetEvent<MyEvent>().Publish(myParams) if (myParams.MyProperty) { // Do something }
// Either of these is fine. myEventAggregator.GetEvent<MyEvent>().Subscribe(MySubscribedMethod) myEventAggregator.GetEvent<MyEvent>().Subscribe(MySubscribedMethod,ThreadOption.PublisherThread) private void MySubscribedMethod(MyEventArgs e) { // Modify event args e.MyProperty = true; }
如果您知道应始终同步调用该事件,则可以为事件创建自己的基类(而不是CompositePresentationEvent< T>),它会覆盖Subscribe方法,并且只允许订阅者使用ThreadOption.PublisherThread选项.它看起来像这样:
public class SynchronousEvent<TPayload> : CompositePresentationEvent<TPayload> { public override SubscriptionToken Subscribe(Action<TPayload> action,ThreadOption threadOption,bool keepSubscriberReferenceAlive,Predicate<TPayload> filter) { // Don't allow subscribers to use any option other than the PublisherThread option. if (threadOption != ThreadOption.PublisherThread) { throw new InvalidOperationException(); } // Perform the subscription. return base.Subscribe(action,threadOption,keepSubscriberReferenceAlive,filter); } }
然后,您不是从CompositePresentationEvent派生MyEvent,而是从SynchronousEvent派生它,它将保证您将同步调用该事件,并且您将获得修改后的EventArgs.