using System;

​

public class Program

{

    public static void Main()

    {

        // create long-lived app context:

        var app = new ApplicationContext("user=blah;password=meh");

        app.Server.Start();

    }

​

    // A pretend database connection object

    class Connection

    {

        public Connection(string connectionString)

        {

            // ...

        }

    }

​

    // A pretend service that operates on user objects in a database

    class UserService

    {

        private Connection connection;

        public UserService(Connection connection)

        {

            this.connection = connection;

        }

    }

    class Server

    {

        private UserService userService;

        public Server(UserService userService)

        {

            this.userService = userService;

        }

        public void Start()

        {

            Console.WriteLine("Starting server...");

        }

    }

​

    // application context:

    class ApplicationContext

    {

        private Lazy<Connection> _connection;

        private Lazy<UserService> _userService;

        private Lazy<Server> _server;

        public ApplicationContext(string connectionString)

        {

            _connection = new(() => new Connection(connectionString));

            _userService = new(() => new UserService(Connection));

            _server = new(() => new Server(UserService));

        }

​

        public Connection Connection { get => _connection.Value; }

        public UserService UserService { get => _userService.Value; }

        public Server Server { get => _server.Value; }

    }

}