Why use EventArgs.Empty instead of null?

c# events eventargs
Greg D picture Greg D · Oct 9, 2008 · Viewed 14.6k times · Source

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

Mitchel Sellers picture Mitchel Sellers · Oct 9, 2008

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.

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