Property setting for Data Model/Business Object transformations with dirty/modified tracking

PropertyHelper.cs

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

namespace Haukcode.DataAccess.Util
{
    internal static class PropertyHelper
    {
        public static void Set<T, TProp>(T target, Expression<Func<T, TProp>> memberLamda, TProp sourceValue, ref bool isDirty)
        {
            Set(target, memberLamda, sourceValue, (a, b) =>
            {
                if (b == null && a == null)
                    return true;

                if ((b == null && a != null) || !b.Equals(a))
                    return false;

                return true;
            }, ref isDirty);
        }

        public static void Set<T, TProp>(T target, Expression<Func<T, TProp>> memberLamda, TProp sourceValue, Func<TProp, TProp, bool> comparer, ref bool isDirty)
        {
            var memberSelectorExpression = memberLamda.Body as MemberExpression;
            if (memberSelectorExpression != null)
            {
                var property = memberSelectorExpression.Member as PropertyInfo;
                if (property != null)
                {
                    var targetValue = (TProp)property.GetValue(target);
                    if (!comparer(sourceValue, targetValue))
                    {
                        // Changed
                        property.SetValue(target, sourceValue, null);
                        isDirty = true;
                    }
                }
                else
                    throw new ArgumentException("Invalid property type");
            }
            else
                throw new ArgumentException("Invalid property");
        }
    }
}