Tag Archives: extension methods

Using extension methods to raise an event

While reviewing some code at work the last days, I noticed I had a lot of similar methods I used to raise events. Basically, I did a test to check if the EventHandler is not null, and in this case, I raise the event:

// declaration of the event
public event EventHandler Saved;

// method I use to raise the event
private void OnSaved()
  if (this.Saved != null)
    this.Saved(this, EventArgs.Empty);

In some of my classes, I had around 10 methods like this one to do the check, and raise the event if the associated event handler is not null. I was thinking about creating an extension method that would do this job for me… And actually, it’s very simple ! Here is the code:

/// Raise an event with a given EventArgs
/// EventHandler to raised
/// Sender of the event
/// Argument of the event
public static void Raise(this EventHandler handler, object sender, EventArgs e)
    if (handler != null)
        handler(sender, e);

Now, I can remove all methods that looks like the first I mentioned in the post, and simply write

Saved.Raise(this, EventArgs.Empty);

I also created an overload of the extension method that does not supply an EventArgs (in case you want to use EventArgs.Empty) and also a generic version (in case you want to use an EventHandler).
You can download the associated class here.