namespace System.Extensions
{
    public static class ObjectExtensions
    {
        public static T Cast<T>(this object obj)
        {
            return (T)obj;
        }

        public static T As<T>(this object obj) where T : class
        {
            return obj as T;
        }

        public static Optional<T> ToOptional<T>(this T obj)
        {
            return Optional.FromValue(obj);
        }

        public static T ThrowIfNull<T>([ValidatedNotNull] this T obj, string name) where T : class
        {
            if (obj is null) throw new ArgumentNullException(name);

            return obj;
        }

        [AttributeUsage(AttributeTargets.Parameter)]
        sealed class ValidatedNotNullAttribute : Attribute
        {
        }
    }
}