using System;

​

//  Domainaton , a singleton prototype class as a derived singleton that can be templated for any business logic or....

//  used as a  common singleton that mutates based on a business module/component / domain, how ever you divide your ...

//  business enterprise system.

// best practice: Like singletons, they must instiate themselves and only one time per lifetime of "app".. not component :)

//                Cannot instiate or change localized singleton (domainaton) at any time... no access to (reflection? well. dont)

//                Base class is a template abstract class and privatized, cannot use as singleton itself

//                template: You can inherit and set constructor to only private.. or protected to extend futher

//                          will check in future, but must set initializer with an action to return new instiation.

//                          any added function to recall new function from child scope is illegal to singleton pattern

//                          senior devs - please hide any domainaton classes privately within one service or class to protect

//                                        only release access to Instance through a safe property of the class / service

//                business global: ex: logging, printing, API calls, common functions can be first level  as domainatons.

//                business domains or app divisions: inherit from first level as domainatons based on business model.2nd level

//                                                   rule of thumb: first level must hide access to Instance as protected.. and

//                                                                  application level services can be it's own business domain in 2nd level                                                                    

// 3rd levels or higher will be antipattern in most application developing models

​

​

​

public abstract class singleton<T>

{

    protected singleton()   {}

​

    private static T instance;

    private static Func<T> act;

    private static readonly object padlock = new object ();

    protected static void initializer(Func<T> action)   {act = action;  }

​

    protected static T Instance

    {

        get

        {

            lock (padlock)

            {

                if (singleton<T>.instance == null) {    instance = act(); }

                return singleton<T>.instance;

            }

        }

    }

}

​

public class Printer : singleton<Printer>

{

    private Printer() { }

​

    public new static Printer Instance

    {

        get

        {

            Printer.initializer(() =>

            {

                Console.WriteLine("System: Printer Singleton Initialized");

                return new Printer();

            });

            return singleton<Printer>.Instance;

        }

    }

​

    public void print(string m) {   Console.WriteLine("To Printer; " + m);  }

}

​

public class Logger : singleton<Logger>

{

    private Logger() {}

​

    public new static Logger Instance

    {

        get

        {

            Logger.initializer(() =>

            {

                 Console.WriteLine("System: Logger Singleton Service initiated");

                 return new Logger();

            });

            return singleton<Logger>.Instance;

        }

    }

    public void log(string m)   {   Console.WriteLine("Logger: " + m);  }

}

​

​

public static class Program

{

    public static void Main()

    {

        Logger.Instance.log("test loegger");

        Logger.Instance.log("hello logger");

        Printer.Instance.print("hello printer");

        Logger.Instance.log("hello logger again");

        // singleton<Logger>.Instance.log("logging");  access hidden :) must create singleton

        //Logger l = new Logger(); access hidden, cannot initialize :)

    }

}