Raising C# events with an extension method - is it bad?
- by Kyralessa
We're all familiar with the horror that is C# event declaration. To ensure thread-safety, the standard is to write something like this:
public event EventHandler SomethingHappened;
protected virtual void OnSomethingHappened(EventArgs e)
{
var handler = SomethingHappened;
if (handler != null)
handler(this, e);
}
Recently in some other question on this board (which I can't find now), someone pointed out that extension methods could be used nicely in this scenario. Here's one way to do it:
static public class EventExtensions
{
static public void RaiseEvent(this EventHandler @event, object sender, EventArgs e)
{
var handler = @event;
if (handler != null)
handler(sender, e);
}
static public void RaiseEvent<T>(this EventHandler<T> @event, object sender, T e)
where T : EventArgs
{
var handler = @event;
if (handler != null)
handler(sender, e);
}
}
With these extension methods in place, all you need to declare and raise an event is something like this:
public event EventHandler SomethingHappened;
void SomeMethod()
{
this.SomethingHappened.RaiseEvent(this, EventArgs.Empty);
}
My question: Is this a good idea? Are we missing anything by not having the standard On method? (One thing I notice is that it doesn't work with events that have explicit add/remove code.)
