Flyweight Pattern Gist

ZoneFactory.cs

    public class ZoneFactory
    {
        private readonly IDictionary<string, Zone> _zones = new Dictionary<string, Zone>();
        private readonly object _lock = new object();

        public Zone GetZone(string zipCode)
        {
            lock (_lock)
            {
                if (_zones.TryGetValue(zipCode, out var zone))
                {
                    return zone;
                }
                
                zone = new Zone(zipCode);
		_zones.Add(zipCode, zone);
                return zone;
            }
        }
    }