INotifyPropertyChanged Helpers

NotificationExtensions.cs

using System;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

namespace Samples
{
    public static class NotificationExtensions
    {
        /// <summary>
        /// Subscribe to PropertyChange notifications for the
        /// given property.
        /// </summary>
        /// <param name="propertyExpression">Lambda expression pointing to the property that you want to receive change notifications for.</param>
        public static void SubscribeToChanges<T>(this T notifier, Expression<Func<object>> propertyExpression,
                                                PropertyChangedEventHandler handler)
            where T : INotifyPropertyChanged
        {
            notifier.PropertyChanged +=
                (s, e) =>
                    {
                        var lambda = propertyExpression as LambdaExpression;
                        MemberExpression memberExpression;
                        if (lambda.Body is UnaryExpression)
                        {
                            var unaryExpression = lambda.Body as UnaryExpression;
                            memberExpression = unaryExpression.Operand as MemberExpression;
                        }
                        else
                        {
                            memberExpression = lambda.Body as MemberExpression;
                        }
                        var propertyInfo = memberExpression.Member as PropertyInfo;

                        if (e.PropertyName.Equals(propertyInfo.Name))
                        {
                            handler(notifier, e);
                        }
                    };
        }
    }
}

NotifyPropertyChangedBase.cs

using System;
using System.ComponentModel;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

namespace Samples
{
    public abstract class NotifyPropertyChangedBase : INotifyPropertyChanged
    {
        #region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion

        /// <summary>
        /// Raises the PropertyChanged event for the given property.
        /// </summary>
        /// <param name="propertyExpression">Lambda expression pointing to the property that the change notification should be raised for.</param>
        /// <example>
        /// Notify( () => PropertyThatChanged );
        /// </example>
        public void Notify(Expression<Func<object>> propertyExpression)
        {
            if (PropertyChanged == null)
                return;

            var lambda = propertyExpression as LambdaExpression;

            MemberExpression memberExpression;
            if (lambda.Body is UnaryExpression)
            {
                var unaryExpression = lambda.Body as UnaryExpression;
                memberExpression = unaryExpression.Operand as MemberExpression;
            }
            else
            {
                memberExpression = lambda.Body as MemberExpression;
            }

            if (memberExpression == null)
            {
                throw new ArgumentException("Expression must be a UnaryExpression or MemberExpression.",
                                            "propertyExpression");
            }

            var propertyInfo = memberExpression.Member as PropertyInfo;

            if (propertyInfo == null)
            {
                throw new ArgumentException("Expression must point to a property.", "propertyExpression");
            }

            PropertyChanged(this, new PropertyChangedEventArgs(propertyInfo.Name));
        }
    }
}