比较器< T> .NET 4中的创建 [英] Comparer<T>.Create in .NET 4

问题描述

我已经在.Net 4.5中创建了一个比较器：

I have created a Comparer in .Net 4.5:

public static Comparer<Room> RoomComparer = 
  Comparer<Room>.Create((a, b) => a.RoomId.CompareTo(b.RoomId))

如何在c＃.NET 4.0中创建比较器？

How can i create Comparer in c# .NET 4.0?

推荐答案

您可以使用以下

public static class Comparer
{
    public static Comparer<T> Create<T>(Comparison<T> comparison)
    {
        if (comparison == null) throw new ArgumentNullException("comparison");
        return new ComparisonComparer<T>(comparison);
    }
    private sealed class ComparisonComparer<T> : Comparer<T>
    {
        private readonly Comparison<T> comparison;
        public ComparisonComparer(Comparison<T> comparison)
        {
            this.comparison = comparison;
        }
        public override int Compare(T x, T y)
        {
            return comparison(x, y);
        }
    }
}

像这样

public static Comparer<Room> RoomComparer = 
  Comparer.Create<Room>((a, b) => a.RoomId.CompareTo(b.RoomId))

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