using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Observed od = new Observed();

        Observer or = new Observer();

        od.ObservedInt += 1;

        Observer2 or2 = new Observer2();

        od.ObservedObject = or;

    }

}

​

public class ObservableObject 

{

    public static void NotifyPropertyChanged(object sender, object propertyValue, EventHandler<CustomEventArgs> handlerDelegate)

    {

        CustomEventArgs e = new CustomEventArgs();

        e.PropertyValue = propertyValue;

        if(handlerDelegate != null)

        {

            handlerDelegate(sender, e);

        }

    }

}

​

public class CustomEventArgs : EventArgs

{

    public object PropertyValue {get; set;} 

}

​

public class Observed : ObservableObject

{

    int _observedInt = 0;

    public static event EventHandler<CustomEventArgs> IntChanged;

    public int ObservedInt

    {

        get{ return _observedInt;}

        set{

            if(value != _observedInt)

            {

                _observedInt = value;

                NotifyPropertyChanged(this, value, IntChanged);

            }

        }

    }

    object _observedObject;

    public static event EventHandler<CustomEventArgs> ObjectChanged;

    public object ObservedObject

    {

        get{ return _observedObject;}

        set{

            if(value != _observedObject)

            {

                _observedObject = value;

                NotifyPropertyChanged(this, value, ObjectChanged);

            }

        }

    }

​

}

​

public class Observer

{

    public Observer()

    {

        Observed.IntChanged += OnIntChange;

        Console.WriteLine("Hello World");

    }

    public void OnIntChange(object sender, CustomEventArgs e)

    {

        Console.WriteLine("sender: {0}. Value: {1} {2}", sender.ToString(), e.PropertyValue.ToString(), e.PropertyValue.GetType());

    }

}

​

public class Observer2

{

    public Observer2()

    {

        Observed.ObjectChanged += OnObjectChange;

        Console.WriteLine("Hello World");

    }

    public void OnObjectChange(object sender, CustomEventArgs e)

    {

        Console.WriteLine("sender: {0}. Value: {1} {2}", sender.ToString(), e.PropertyValue.ToString(), e.PropertyValue.GetType());

    }

}

​

​

​

​

​

​

​

​