using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Runtime.CompilerServices;

​

public class Program

{

    public static void Main()

    {

        using (var model = new CustomerModel()) {

            model.PropertyChanged += (sender, e) => {

                Console.WriteLine("{0}: {1}", e.PropertyName, sender.GetType().GetProperty(e.PropertyName).GetValue(sender));

            };

            model.CustomerName = "Efraín Reyes";

            model.OrderCount = 5;

            model.CustomerName = "Efraín Reyes";

            model.OrderCount = 5;

            model.CustomerName = null;

            model.CustomerName = null;

            model.CustomerName = null;

        }

    }

}

​

public abstract class ModelBase : INotifyPropertyChanged, IDisposable {

    private event PropertyChangedEventHandler _propertyChanged;

    private List<PropertyChangedEventHandler> _propertyChangedSubscribers =

        new List<PropertyChangedEventHandler>();

    // this is Miguel Castro's technique from his Pluralsight course

    // where he can add a delegate to an event handler 

    // without having to worry about duplicates

    public event PropertyChangedEventHandler PropertyChanged {

        add {

            if (!_propertyChangedSubscribers.Contains(value)) {

                _propertyChanged += value;

                _propertyChangedSubscribers.Add(value);

            }

        }

        remove {

            _propertyChanged -= value;

            _propertyChangedSubscribers.Remove(value);

        }

    }

    private void NotifyPropertyChanged(string propertyName = "")

    {

        if (_propertyChanged != null)

        {

            _propertyChanged(this, new PropertyChangedEventArgs(propertyName));

        }

    }

    protected void SetProperty<T>(ref T field, T value, [CallerMemberName]string property = "") {

        if (!EqualityComparer<T>.Default.Equals(field, value)) {

            field = value;

            NotifyPropertyChanged(property);

        }

    }

    // my own little twist

    // http://stackoverflow.com/q/1061727/2563028

    // this way instead of unregistering event handlers manually

    // one can simply Dispose() the object

    public void Dispose() {

        _propertyChanged = null;

        _propertyChangedSubscribers.Clear();

    }

}

​

public class CustomerModel : ModelBase {

    private string _customerName;

    public string CustomerName {

        get { return _customerName; }

        set { SetProperty(ref _customerName, value); }

    }

    private int _orderCount;

    public int OrderCount {

        get { return _orderCount; }

        set { SetProperty(ref _orderCount, value); }

    }

}