Question

I subscribe to an Event inside a class. Such as

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

My MainStation class raises the event on some condition by just calling the event FrequencyChanged()

The Problem

Now I have a scenario where I must instantiate SubStation from MainStation which is also a subclass of MainStation with some additional features and FrequencyChanged event must be subscribed as the MainStation subscrbed. Consider the code noted below:

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
    }
}

Bottom Line
I want to fire an event that a class subscribes from another class, also bubble up events

Update
StationFactory creates MainStation and the FrequencyChanged event in MainStation instance is set as defined in the first code block.

Answer 1

If FrequencyChanged does not belong to MainStation, but rather to some Base, you’re going to have to chain and expose the event you’re interested in.

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
{

}