sharp-chat/SharpChat/Packet/UserUpdatePacket.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace SharpChat.Packet {
    public class UserUpdatePacket : ServerPacket {
        public ChatUser User { get; private set; }

        public UserUpdatePacket(ChatUser user) {
            User = user ?? throw new ArgumentNullException(nameof(user));
        }

        public override IEnumerable<string> Pack() {
            StringBuilder sb = new();

            sb.Append("10");
            sb.Append('\t');
            sb.Append(User.Pack());

            yield return sb.ToString();
        }
    }
}