Is there a design pattern I can use for a situation like below.  This is an example I made up to try and explain the situation I'm dealing with currently.  I keep having to add new DeviceScript classes to my DeviceAnalyzer as situation come up and adding logic about when to return the new type in the 'GetScriptForDevice'.   This example I have given is pretty simple but the business logic I'm having to implement for my real 'GetScriptForDevice' isn't always this easy.  Any suggestions on a pattern or an example of a better way to structure this code to follow a better pattern would be greatly appreciated.  I'm violating OCP every time I need to add a new DeviceScript and I'm trying to find a way around this because my class is getting quite long and fragile.Thanks.public class DeviceScript {    public string Name { get; set; }    public string SecurityScriptName { get; set; }    public string BusinessScriptName { get; set; }}public class DeviceAnalyzer {    public const string US_SecurityScript = US_SecurityScript;    public const string US_BusinessScript = US_BusinessScript;    public const string UK_SecurityScript = UK_SecurityScript;    public const string UK_BusinessScript = UK_BusinessScript;     private DeviceScript UnitedStates = new DeviceScript {         Name = US_Script,         SecurityScriptName = US_SecurityScript,         BusinessScriptName = US_BusinessScript     };     private DeviceScript UnitedKingdom = new DeviceScript {         Name = UK_Script,         SecurityScriptName = UK_SecurityScript,         BusinessScriptName = UK_BusinessScript     };     public DeviceScript GetScriptForDevice(IDevice device) {         if(device.Location == Locations.US) {          return UnitedStates;         }         if(device.Location == Locations.UK) {          return UnitedKingdom;         }        return null;     }}
Design Pattern Question/Violating OCP
c#;design patterns
I would suggest something like thatpublic interface IDeviceScript{    string Name { get; }    string SecurityScriptName { get; }    string BusinessScriptName { get; }    bool IsScriptApply(IDevice device);}public interface IDevice{    Locations Location { get; }    // more methods and properties}[Serializable][AttributeUsage(AttributeTargets.Class)]public class DeviceScriptAttribute : Attribute{}[DeviceScript]public class UnitedStatesScript : IDeviceScript{    public string Name    {        get { return US_Script; }    }    public string SecurityScriptName    {        get { return US_SecurityScript; }    }    public string BusinessScriptName    {        get { return US_BusinessScript; }    }    public bool IsScriptApply(IDevice device)    {        return device.Location == Locations.US;    }}public IDeviceScript GetScriptForDevice(IDevice device){    IEnumerable<IDeviceScript> deviceScripts =        Assembly.GetExecutingAssembly()                .GetTypes()                .Where(t => t.GetCustomAttributes<DeviceScriptAttribute>().Any())                .Select(t => Activator.CreateInstance(t))                .Cast<IDeviceScript>();    foreach (IDeviceScript deviceScript in deviceScripts)    {        if (deviceScript.IsScriptApply(device))        {            return deviceScript;        }    }    return null;}Now you can add more scripts just by adding new classes to your project. No xml configs are required :)Futher suggestions:After calculating deviceScripts enumerable once you can store it in some static field for further use.Name property of IDeviceScript could be moved to DeviceScriptAttribute if you don't need it in your code.I would make GetScriptForDevice method static but unfortunately .net doesn't support statics in interfaces :(