C#中自定义事件的注意事项

一个类中定义如下事件：

public delegate void AfterDrawPointEvent(object sender,double x,double y);

private AfterDrawPointEvent pAfterDrawPointEvent; /// <summary> /// 插入要素事件 /// </summary> public event AfterDrawPointEvent AfterDrawpoint { add { pAfterDrawPointEvent += value; } remove { pAfterDrawPointEvent -= value; } } private void RaiseAfterDrawPointEvent(object sender, double x,double y) { if (pAfterDrawPointEvent != null) { pAfterDrawPointEvent(sender,x,y); } }然后定义实现的响应方法，注意要先去掉旧的响应方法，否则可能出现部分变量的状态无法更新。代码如下：

m_pDrawCustomPoint.AfterDrawpoint-= new DrawCustomPoint.AfterDrawPointEvent(m_pDrawCustomPoint_AfterDrawpoint); m_pDrawCustomPoint.AfterDrawpoint += new DrawCustomPoint.AfterDrawPointEvent(m_pDrawCustomPoint_AfterDrawpoint);