using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var foos = GetFoos();

        // var foos = GetFoosWithForeach();

        foos.Take(5).Dump();

    }

    public static IEnumerable<int> GetFoos()

    {

        using (var fooSource = new DisposableFoo())

        {

            return fooSource.GetFoos(); 

        }

    }

    public static IEnumerable<int> GetFoosWithForeach()

    {

        using (var fooSource = new DisposableFoo())

        {

            foreach (var foo in fooSource.GetFoos())

                yield return foo;

        }

    }

    public class DisposableFoo : IDisposable

    {

        public bool Disposed { get; set; }

        public void Dispose()

        {

            Dispose(true);

            GC.SuppressFinalize(this);

        }

        protected virtual void Dispose(bool disposing)

        {

            Disposed = true;

        }

        public IEnumerable<int> GetFoos()

        {

            while (true)

            {

                if (Disposed)

                    throw new ObjectDisposedException("");

                yield return 1;

            }

        }

    }

}