/// <summary>
/// Initializes a new instance of the <see cref="CompoundComparer<T>"/> class.
/// </summary>
/// <param name="source">The source comparer. If this is <c>null</c>, the default comparer is used.</param>
/// <param name="secondSource">The second comparer. If this is <c>null</c>, the default comparer is used.</param>
public CompoundComparer(IComparer <T> source, IComparer <T> secondSource)
: base(source, true)
{
this.secondSource_ = ComparerHelpers.NormalizeDefault(secondSource);
}
/// <summary>
/// Initializes a new instance of the <see cref="SourceComparerBase<T, TSource>"/> class.
/// </summary>
/// <param name="source">The source comparer. If this is <c>null</c>, the default comparer is used.</param>
/// <param name="allowNulls">A value indicating whether <c>null</c> values are passed to <see cref="EqualityComparerBase{T}.DoGetHashCode"/> and <see cref="ComparerBase{T}.DoCompare"/>. If <c>false</c>, then <c>null</c> values are considered less than any non-<c>null</c> values and are not passed to <see cref="EqualityComparerBase{T}.DoGetHashCode"/> nor <see cref="ComparerBase{T}.DoCompare"/>.</param>
protected SourceComparerBase(IComparer <TSource> source, bool allowNulls)
: base(allowNulls)
{
this.source_ = ComparerHelpers.NormalizeDefault(source);
}