/// <summary>
/// Orders the ordered observable by a further sorting criterion descendingly.
/// </summary>
/// <typeparam name="T">The element type of the source and result observables.</typeparam>
/// <typeparam name="TSelect">The type of the selected sorting criterion.</typeparam>
/// <param name="source">The observable to sort.</param>
/// <param name="selector">The selector to select the sorting criterion.</param>
/// <param name="comparer">The comparer to compare the sorting criterion.</param>
/// <returns>The new observable instance.</returns>
public static IOrderedAsyncObservable <T> ThenByDescending <T, TSelect>(this IOrderedAsyncObservable <T> source, Func <T, TSelect> selector, IComparer <TSelect> comparer)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
return(source.CreateOrderedObservable(selector, comparer, true));
}
/// <summary>
/// Orders the ordered observable by a further sorting criterion ascendingly.
/// </summary>
/// <typeparam name="T">The element type of the source and result observables.</typeparam>
/// <typeparam name="TSelect">The type of the selected sorting criterion.</typeparam>
/// <param name="source">The observable to sort.</param>
/// <param name="selector">The selector to select the sorting criterion.</param>
/// <returns>The new observable instance.</returns>
public static IOrderedAsyncObservable <T> ThenBy <T, TSelect>(this IOrderedAsyncObservable <T> source, Func <T, TSelect> selector)
{
if (source == null)
{
throw new ArgumentNullException(nameof(source));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
return(source.CreateOrderedObservable(selector, null, false));
}