using System;

​

​

namespace Example

{

    public interface INotificationArgs

    {

    }

    public interface INotify<out T> where T: EventArgs, INotificationArgs

    {

        void PrintName();

    }

    public class MyEventArgsBase : EventArgs, INotificationArgs {}

​

    public class MyEventArgs1 : MyEventArgsBase {}

    public class MyEventArgs2 : MyEventArgsBase {}

    public class MyEventArgs3 : MyEventArgsBase {}

    class MyClass<T> : INotify<T> where T : EventArgs, INotificationArgs

    {

        public string Name { get; set; }

        public MyClass(string name) { Name = name; }

        public void PrintName()

        {

            Console.WriteLine(Name);

        }

    }

    public class Program

    {

        private static void doSomethingWithINotifyObject<T>(INotify<T> notify) where T : EventArgs, INotificationArgs

        {

            notify.PrintName();

        }

        public static void Main()

        {

            object[] tests = new object []

            {

                new MyClass<MyEventArgs1>("1"),

                new MyClass<MyEventArgs2>("2"),

                new MyClass<MyEventArgs3>("3")

            };

            foreach (var o in tests)

            {

                var i = o as INotify<MyEventArgsBase>;

                if (i != null)

                {

                    doSomethingWithINotifyObject(i);

                }

            }

        }

    }

}

​