C# lambda expressions and IComparer

Question

I am using lambda expressions to sort and search an array in C#. I don\'t want to implement the IComparer interface in my class, because I need to sort and search on multiple m

Answer 1

Try this:

public static class ComparisonEx
{
    public static IComparer AsComparer(this Comparison @this)
    {
        if (@this == null)
            throw new System.ArgumentNullException("Comparison @this");
        return new ComparisonComparer(@this);
    }

    public static IComparer AsComparer(this Func @this)
    {
        if (@this == null)
            throw new System.ArgumentNullException("Func @this");
        return new ComparisonComparer((x, y) => @this(x, y));
    }

    private class ComparisonComparer : IComparer
    {
        public ComparisonComparer(Comparison comparison)
        {
            if (comparison == null)
                throw new System.ArgumentNullException("comparison");
            this.Comparison = comparison;
        }

        public int Compare(T x, T y)
        {
            return this.Comparison(x, y);
        }

        public Comparison Comparison { get; private set; }
    }
}

It lets you use this code:

Comparison c = (x, y) => x == y ? 0 : (x <= y ? -1 : 1);
IComparer icc = c.AsComparer();

Func f = (x, y) => x == y ? 0 : (x <= y ? -1 : 1); 
IComparer icf = f.AsComparer();