Notes

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

namespace Observer1
{
class Program
{
static void Main(string[] args)
{

Auctioneer auctioneer = new Auctioneer();
auctioneer.Attach(new Bidder(auctioneer, "1.Gözlemci"));
auctioneer.Attach(new Bidder(auctioneer, "2.Gözlemci"));
auctioneer.Attach(new Bidder(auctioneer, "3.Gözlemci"));

auctioneer.State = AuctionStatus.increase;
auctioneer.Notify();

}
}

public interface IObserver
{
void Update();
}

public interface ISubject
{
void Attach(IObserver subscriber);
void Detach(IObserver subscriber);
void Notify();
}
public enum AuctionStatus
{
increase,
sell
}
public class Bidder : IObserver
{
Auctioneer _subject;
string _name;
public Bidder(Auctioneer subject, string name)
{
this._subject = subject;
this._name = name;

}

public void Update()
{
AuctionStatus status = _subject.State;
_subject.Detach(this);
}
}

public class Auctioneer : ISubject
{
private AuctionStatus _auctionStatus;
private List<IObserver> _subscribers = null;

public Auctioneer()
{
_subscribers = new List<IObserver>();
}

public AuctionStatus State
{
get
{
return _auctionStatus;
}
set
{
_auctionStatus = value;
}
}


public void Attach(IObserver subscriber)
{
foreach (var item in _subscribers)
{
if (_subscribers.Any(x => x.Equals(item) == false))
{
_subscribers.Add(subscriber);
break;
}
}
}


public void Detach(IObserver subscriber)
{
foreach (var item in _subscribers)
{
if (_subscribers.Any(x => x.Equals(item)))
{
_subscribers.Remove(subscriber);
break;
}
}

}

public void Dispose()
{
GC.SuppressFinalize(this);
this.Dispose();
}



public void Notify()
{
foreach (IObserver item in _subscribers)
{
item.Update();
}
}
}
}