using System;

​

public class Program

{

    public static void Main()

    {

        // create long-lived app context:

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

        var request = new WebRequest(); // pretend we're getting a web request

        // create a short-lived request context for a given request:

        var requestContext = new RequestContext(app, request);

        // now you can create/fetch a controller instance:

        var controller = requestContext.ListUsersController;

    }

​

    // A pretend database connection object

    class Connection

    {

        public Connection(string connectionString)

        {

        }

    }

​

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

    class UserService

    {

        public UserService(Connection c)

        {

        }

    }

​

    // a pretend web request that 

    class WebRequest

    {

        public WebRequest()

        {

        }

    }

​

    class ListUsersController

    {

        public ListUsersController(UserService u, WebRequest r)

        {

        }

    }

​

    // application context:

    class ApplicationContext

    {

        private Lazy<Connection> _connection;

        private Lazy<UserService> _userService;

        public ApplicationContext(string connectionString)

        {

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

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

        }

​

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

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

    }

​

    // request context - same pattern, but constructor depends on application context + a specific web request:

    class RequestContext

    {

        private Lazy<ListUsersController> _listUsersController;

        public RequestContext(ApplicationContext app, WebRequest request)

        {

            _listUsersController = new(() => new ListUsersController(app.UserService, request));

        }

​

        public ListUsersController ListUsersController { get => _listUsersController.Value; }

    }

}