Handy methods for property reflection, and subscription to properties in MVVM

PropertyUtil.cs

  
/// <summary>
/// Methods for handling property names and values, using reflection.
/// </summary>
public static class PropertyUtil
{
    public static string GetPropertyName<TObject, TValue>(this TObject type,
        Expression<Func<TObject, TValue>> propertySelector)
    {
        return GetPropertyNameCore(propertySelector.Body);
    }

    public static string GetPropertyName<TObject, TValue>(Expression<Func<TObject, TValue>> propertySelector)
    {
        return GetPropertyNameCore(propertySelector.Body);
    }

    private static string GetPropertyNameCore(Expression propertySelector)
    {
        if (propertySelector == null)
            throw new ArgumentNullException("propertySelector", "propertyRefExpr is null.");

        MemberExpression memberExpr = propertySelector as MemberExpression;
        if (memberExpr == null)
        {
            UnaryExpression unaryExpr = propertySelector as UnaryExpression;
            if (unaryExpr != null && unaryExpr.NodeType == ExpressionType.Convert)
                memberExpr = unaryExpr.Operand as MemberExpression;
        }

        if (memberExpr != null && memberExpr.Member.MemberType == MemberTypes.Property)
            return memberExpr.Member.Name;

        throw new ArgumentException("No property reference expression was found.",
            "propertySelector");
    }

    public static void SetValueForProperty<TObject, TValue>(this TObject type, Expression<Func<TObject, TValue>> propertySelector, TValue value)
    {
        string propertyName = type.GetPropertyName(propertySelector);
        var property = type.GetType().GetProperty(propertyName);
        property.SetValue(type, value, null);
    }

    public static object GetValueForProperty<TObject, TValue>(this TObject type, Expression<Func<TObject, TValue>> propertySelector)
    {
        string propertyName = type.GetPropertyName(propertySelector);
        var property = type.GetType().GetProperty(propertyName);
        return property.GetValue(type, null);
    }

    public static void SubscribeToProperty<T>(this T me, Expression<Func<T, object>> propertySelector, Action<T> callback) where T : INotifyPropertyChanged
    {
        var propertyName = GetPropertyName(propertySelector);
        me.PropertyChanged += (sender, args) =>
        {
            if (args.PropertyName == propertyName)
            {
                callback(me);
            }
        };
    }
}