安全事件

public static class EventHandlerExtensions
{
    public static void SafeInvoke<T>(this EventHandler<T> evt, object sender, T e) where T : EventArgs
    {
        if (evt != null)
        {
            evt(sender, e);
        }
    }
}

Using that method, you can invoke the events like this:

protected void OnSomeEvent(EventArgs e)
{
    SomeEvent.SafeInvoke(this, e);
}