事件 event Action

public class A{    public event Action OnStateChanged;}public class B{    public A Stage;    public event Action OnXXStageChanged    {        add         {            if(Stage != null){                Stage.OnStateChanged += value;            }        }        remove        {            if(Stage != null){                Stage.OnStateChanged -= value;            }        }    }    }public class C{    void test()    {        B b = new B();        b.OnXXStageChanged += f;        b.OnXXStageChanged -= f;    }    void f()    {    }}

这么做的目的是可以把A中的时间封装起来