Why use EventArgs.Empty instead of null?

Question

I recall reading, on multiple occasions and in multiple locations, that when firing the typical event:

protected virtual OnSomethingHappened() {     this.SomethingHappened(this, EventArgs.Empty); } 

e should be EventArgs.Empty if there are no interesting event args, not null.

I've followed the guidance in my code, but I realized that I'm not clear on why that's the preferred technique. Why does the stated contract prefer EventArgs.Empty over null?

Answer 1

I believe the reasoning behind the NOT NULL is that when passed as a parameter, it is not expected for the method to need to potentially handle a null reference exception.

If you pass null, and the method tries to do something with e it will get a null reference exception, with EventArgs.Empty it will not.

Answer 2

EventArgs.Empty is an instance of the Null object pattern.

Basically, having an object representing "no value" to avoid checking for null when using it.