namespace Chernobyl.Event
{
    /// <summary>
    /// An event argument used when an instance of some type has been changed by
    /// the invoker of the event.
    /// </summary>
    /// <typeparam name="T">The type of the values being changed.</typeparam>
    public class ValueChangedEventArgs<T> : ItemsEventArgs<T>
    {
        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="oldValue">The previous value of the item before it was 
        /// changed.</param>
        /// <param name="newValue">The new value of the item.</param>
        public ValueChangedEventArgs(T oldValue, T newValue) : base(oldValue, newValue)
        {
            OldValue = oldValue;
            NewValue = newValue;
        }

        /// <summary>
        /// The old item or the previous value of the item before it was 
        /// changed.
        /// </summary>
        public T OldValue { get; protected set; }

        /// <summary>
        /// The new item that was placed in the list.
        /// </summary>
        public T NewValue { get; protected set; }
    }
}