c# - When should you override OnEvent as opposed to subscribing to the event when inheritting

Question

When should one do the following?

class Foo : Control
{
    protected override void OnClick(EventArgs e)
    {
        // new code here
    }
}

As opposed to this?

class Foo : Control
{
    public Foo()
    {
        this.Click += new EventHandler(Clicked);
    }

    private void Clicked(object sender, EventArgs e)
    {
        // code
    }
}

Answer 1

Overriding rather than attaching a delegate will result in more efficient code, so it is generally recommended that you always do this where possible. For more information see this MSDN article. Here is a pertinent quote:

The protected OnEventName method also allows derived classes to override the event without attaching a delegate to it. A derived class must always call the OnEventName method of the base class to ensure that registered delegates receive the event.