class Program
    {
        static void Main(string[] args)
        {
            var map = Map(testInt: 5, testString: "hello");

            map.testDouble = 10.5;

            map[10] = "number 10";

            Console.WriteLine(map.testInt);
            Console.WriteLine(map.testString);
            Console.WriteLine(map.testDouble);
            Console.WriteLine(map[10]);
            map.Remove(10);
            Console.WriteLine(map[10, "10 default"]);
            Console.WriteLine(map[15, "15 default"]);

            Console.ReadLine();
        }

        static dynamic Map { get => new DynamicDictFactory(); }
    }

    public class DynamicDictFactory : DynamicObject
    {
        private Dictionary<dynamic, dynamic> res = new Dictionary<dynamic, dynamic>();

        public void Clear() => res.Clear();
        public void Remove(object key) => res.Remove(key);

        public override bool TrySetMember(SetMemberBinder binder, object value)
        {
            res[binder.Name] = value;
            return true;
        }

        public override bool TrySetIndex(SetIndexBinder binder, object[] indexes, object value)
        {
            res[indexes[0]] = value;
            return true;
        }

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            if (res.ContainsKey(binder.Name))
                result = res[binder.Name];
            else throw new ArgumentException();
            return true;
        }

        public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object result)
        {
            if (res.ContainsKey(indexes[0]))
                result = res[indexes[0]];
            else if (indexes.Length > 1)
                result = indexes[1];
            else throw new ArgumentException();
            return true;
        }

        public override bool TryInvoke(InvokeBinder binder, object[] args, out object result)
        {
            var names = binder.CallInfo.ArgumentNames;

            for (var i = 0; i < args.Length; i++)
            {
                var argName = names[i];
                if (string.IsNullOrEmpty(argName)) throw new ArgumentException();
                res[argName] = args[i];
            }
            result = this;
            return true;
        }
    }