StructExtensions.cs

using System.Collections.Generic;
using System.Reflection;
using System.Linq;

namespace Sonorous.Core.Services
{
    public static class StructExtensions
    {
        public delegate bool TryParseDelegate<T>(string input, out T value);

        public static T? TryParse<T>(this string input)
            where T : struct
        {
            var methodInfo = typeof(T).GetMethods(BindingFlags.Static | BindingFlags.Public)
                .FirstOrDefault(mi => mi.Name == "TryParse" && mi.GetParameters().Length == 2);

            if (methodInfo == null)
                return null;

            var selector = (TryParseDelegate<T>)methodInfo.CreateDelegate(typeof(TryParseDelegate<T>));
            return input.TryParse(selector);
        }

        public static T? TryParse<T>(this string input, TryParseDelegate<T> selector)
            where T : struct
        {
            T result;
            if (selector(input, out result))
                return result;

            return null;
        }

        public static IEnumerable<T?> AsNullable<T>(this IEnumerable<T> items)
            where T : struct
        {
            return items.Cast<T?>();
        }
    }
}