// Licensed to the .NET Foundation under one or more agreements. // The .NET Foundation licenses this file to you under the MIT license. // See the LICENSE file in the project root for more information. /*============================================================ ** ** ** ** ** ** Purpose: Interface for exposing an Observer in the ** Observer pattern ** ** ===========================================================*/ using System; namespace System { public interface IObserver { void OnNext(T value); void OnError(Exception error); void OnCompleted(); } }