Observer design Pattern

When many objects needs to recieve updates when there is a change in another objects,
Benifit =
Loosely coupled – publishers need not be aware of the type of subscriber (observer)

Flaws
The publishers( subject ) may send updates that dont matter to the subscriber (observer)


using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

// Liskov Substitution Principle

namespace ManualResetEvent_
{
    interface IPublisher
    {
        void register(Subscriber subscriber);
        void unregister(Subscriber subscriber);
        void notify();
    }


    class publisher_ : IPublisher
    {
        private int no_of_items;
        private List<Subscriber> subscriber_list = new List<Subscriber>();
        public int inventory
        {
            get { return no_of_items; }
            set
            {
                if (no_of_items < value)
                    notify();
                no_of_items = value;
            }
        }

       public void register(Subscriber subscriber)
        {
            subscriber_list.Add(subscriber);
        }

        public void unregister(Subscriber subscriber)
        {
            subscriber_list.Remove(subscriber);
        }

        public void notify()
        {
            subscriber_list.ForEach(x => x.Update());
        }

    }

        class Subscriber : ISubscriber
        {
            public string Subscriber_name;
            public string Name
            {
                get{return Subscriber_name;}
                private set{}
            }

            public Subscriber(string name)
            {
                Subscriber_name =name;
            }

            public void Update()
            {
                Console.WriteLine(this.Subscriber_name+"A new product is introduced ");
            }

        }

        interface ISubscriber
        {
            void Update();
        }

        class program
        {
            public static void Main()
            {
                Subscriber sub_1 = new Subscriber("Moto");
                Subscriber sub_2 = new Subscriber("Nokia");
                Subscriber sub_3 = new Subscriber("MI");
                publisher_ pub1 = new publisher_();
                pub1.register(sub_1);
                pub1.register(sub_2);
                pub1.register(sub_3);
                pub1.inventory++;
                pub1.unregister(sub_3);
                pub1.inventory++;

                Console.ReadLine();


               


            }

        }
       

    }