using System;

using System.Windows;

public class Program

{

    public static void Main()

    {

        var foo = new Foo();

​

        Console.WriteLine( "Set foo.Bar to 1" );

        foo.Bar = 1;

        Console.WriteLine( "Set foo.Bar to 1 (assigning the same value)" );

        foo.Bar = 1;

        Console.WriteLine( "Set foo.Bar to 2" );

        foo.Bar = 2;

    }

}

​

public class Foo : DependencyObject

{

    public int Bar

    {

        get { return (int) GetValue( BarProperty ); }

        set { SetValue( BarProperty, value ); }

    }

​

    public static readonly DependencyProperty BarProperty =

        DependencyProperty.Register(

            "Bar",

            typeof( int ),

            typeof( Foo ),

            new PropertyMetadata(

                defaultValue: 0,

                propertyChangedCallback: new PropertyChangedCallback( OnBarChanged ) ) );

​

    private static void OnBarChanged( DependencyObject d, DependencyPropertyChangedEventArgs e )

    {

        Console.WriteLine( "OnBarChanged: Property has changed from '{0}' to '{1}'", e.OldValue, e.NewValue );

    }

}