“自定义事件”如何在VB.Net中运行?
发布时间:2020-12-17 00:20:19 所属栏目:大数据 来源:网络整理
导读:在C#中如果我想创建一个“自定义事件”,你可以这样做: private EventHandler _MyEvent;Public Event EventHandler MyEvent { add{ _MyEvent += value; } remove{ _MyEvent -= Value; }}protected void RaiseMyEvent(){ if(_MyEvent != nul) _MyEvent(this,E
在C#中如果我想创建一个“自定义事件”,你可以这样做:
private EventHandler _MyEvent; Public Event EventHandler MyEvent { add{ _MyEvent += value; } remove{ _MyEvent -= Value; } } protected void RaiseMyEvent() { if(_MyEvent != nul) _MyEvent(this,EventArgs.Empty); } 在VB中,这不是那么简单,我也无法在网上找到任何帮助. private _MyEvent as EventHandler Public Custom Event MyEvent as EventHandler AddHandler(ByVal value as EventHandler) _MyEvent += value 'does not work addhandler _MyEvent,value 'does not work [Delegate].Combine(_MyEvent,value) '_MyEvent still nothing End AddHandler RemoveHandler(ByVal value as EventHandler) 'Same kind of stuff here End RemoveHandler RaiseEvent(sender as Object,e as EventArgs) if(_MyEvent IsNot Nothing) Then '_MyEvent is always nothing _MyEvent.Invoke(sender,e) End If End RaiseEvent End Event 请帮忙.
委托是不可变的,因此方法“[Delegate] .Combine”返回新委托,但不修改参数.所以你需要:
_MyEvent = [Delegate].Combine(_MyEvent,value) (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |