Monday, January 07, 2008

Yet another use for Extension methods : Extending IComparable

by wwagner via Bill Wagner: C# Development Blog | MySmartChannels on 1/7/2008 2:19:00 PM

I keep finding more uses for extension methods. This time it's extending IComparable<T>. The API signature for IComparable<T> has been around since the dawn of C: if the left is less than the right, return something less than 0, if left is greater than right, return something greater than 0, and if they are equivalent, return 0. Well, its readability leaves a bit to be desired.

So I wrote this set of extension methods for any type T that implements IComparable<T>:

public static class EquatableExtensions
{
    public static bool GreaterThan<T>(this T left, T right) where T : IComparable<T>
    {
        return left.CompareTo(right) > 0;
    }

    public static bool LessThan<T>(this T left, T right) where T : IComparable<T>
    {
        return left.CompareTo(right) < 0;
    }

    public static bool GreaterThanOrEqual<T>(this T left, T right) where T : IComparable<T>
    {
        return left.CompareTo(right) >= 0;
    }

    public static bool LessThanOrEqual<T>(this T left, T right) where T : IComparable<T>
    {
        return left.CompareTo(right) <= 0;
    }

    public static bool Equal<T>(this T left, T right) where T : IComparable<T>
    {
        return left.CompareTo(right) == 0;
    }
}

These methods mean I can write this:

if (foo.GreaterThan(bar))

instead of

if (foo.CompareTo(bar) > 0)

personally, I find the former much easier to read.

Ok, this is not rocket science, but it's useful, and it improves the readability of quite a bit of the code I work with on a day to day basis.