C# 事件传递/冒泡

Question

我在 class 中订阅了一个 Event。比如

MainStation mainStation = StationFactory.GetMainStation();  
mainStation.FrequencyChanged += new EventArgs(MainStation_FrequencyChanged);

我的 MainStation 类通过调用事件 FrequencyChanged() 在某些情况下引发事件

问题

现在我有一个场景，我必须从 MainStation 实例化 SubStation，它也是 MainStation 的子类具有一些附加功能和 FrequencyChanged 事件必须作为 MainStation 订阅。考虑以下代码:

public class MainStation
{
    public event EventHandler FrequencyChanged;
    public static SubStation CreateSubStation()
    {
        SubStation subStation = new SubStation();
        //here I want to pass/bubble FrequencyChanged event to SubStation
        subStation.FrequencyChanged = FrequencyChanged; //THIS IS WRONG
    }
}

底线
我想触发一个类从另一个类订阅的事件，也冒泡事件

更新
StationFactory 创建 MainStation 并且 MainStation 实例中的 FrequencyChanged 事件设置为第一个代码块中定义的。

Answer 1

如果 FrequencyChanged 不属于 MainStation，而是属于某个 Base，您将不得不链接并公开事件你感兴趣。

public class MainStation : Base
{
    public event EventHandler StationFrequencyChanged;

    public MainStation()
    {
        // ...

        this.FrequencyChanged += new EventHandler(MainStation_FrequencyChanged);
    }

    void MainStation_FrequencyChanged(object sender, EventArgs e)
    {
        if (StationFrequencyChanged != null)
            StationFrequencyChanged(sender, e);
    }

    public void GetEventsFrom(MainStation src)
    {
        //this is where you assign src events to your object
        this.StationFrequencyChanged = src.StationFrequencyChanged;
    }

    public static SubStation CreateSubStation(MainStation main)
    {
        SubStation subStation = new SubStation();

        //register events    
        subStation.GetEventsFrom(main);

        return subStation;
    } 
}

public class SubStation : MainStation
{

}