Constructor Injection in CodeIgniter controllers. Also resolves nested dependencies.

booking.php

<?php

use Nelissen\LooseCI\Services\BookingService;

class Booking extends CI_Controller
{

    /**
     * @var \Nelissen\LooseCI\Services\BookingService
     */
    private $booking;

    /**
     * @param BookingService $booking
     */
    public function __construct(BookingService $booking)
    {
        parent::__construct();

        $this->booking = $booking;
    }

    // etc

}

BookingService.php

<?php namespace Nelissen\LooseCI\Services;

use Nelissen\LooseCI\Repositories\Room\RoomRepositoryInterface;
use Nelissen\LooseCI\Repositories\Booking\BookingRepositoryInterface;
use Nelissen\LooseCI\Repositories\Booker\BookerRepositoryInterface;
use Nelissen\LooseCI\Models\Room;
use Nelissen\LooseCI\Models\Booker;
use Nelissen\LooseCI\Exceptions\BookingExceedsRoomCapacityException;

/**
 * Class BookingService
 *
 * @author Kaj Nelissen
 * @package Nelissen\LooseCI\Services
 */
class BookingService
{

    /**
     * @var
     */
    private $bookingRepo;

    /**
     * @var
     */
    private $roomRepo;

    /**
     * @var
     */
    private $bookerRepo;

    /**
     * @param BookingRepositoryInterface $bookingRepo
     * @param RoomRepositoryInterface $roomRepo
     * @param BookerRepositoryInterface $bookerRepo
     */
    public function __construct(BookingRepositoryInterface $bookingRepo,
                                RoomRepositoryInterface $roomRepo,
                                BookerRepositoryInterface $bookerRepo)
    {
        $this->bookingRepo = $bookingRepo;
        $this->bookerRepo = $bookerRepo;
        $this->roomRepo = $roomRepo;
    }

    // etc

}

CodeIgniter.php

<?php

    // CI code

    // insert following before the line $CI = new $class();
    $ioc = new \Illuminate\Container\Container();

    // bind interfaces to concrete implementation in order to resolve
    $ioc->bind('Nelissen\LooseCI\Repositories\Booking\BookingRepositoryInterface', 'Nelissen\LooseCI\Repositories\Booking\CIBookingRepository');
    $ioc->bind('Nelissen\LooseCI\Repositories\Booker\BookerRepositoryInterface', 'Nelissen\LooseCI\Repositories\Booker\CIBookerRepository');
    $ioc->bind('Nelissen\LooseCI\Repositories\Room\RoomRepositoryInterface', 'Nelissen\LooseCI\Repositories\Room\CIRoomRepository');

    // then replace $CI = new $class(); with
    $CI = $ioc->build($class);

    // $CI is now an instantiation of the requested controller
    // however, all constructor parameters are automatically resolved out of the IoC container
    // thus, improving testability

composer.json

{
    "name": "Nelissen/LooseCI",
    "description": "Just a proof of concept demonstrating some tricks to decouple and test CodeIgniter.",
    "keywords": ["codeigniter"],
    "license": "GPL-2.0",
    "authors": [
        {
            "name": "Kaj Nelissen"
        }
    ],
    "require": {
        "php": ">=5.3.0",
        "illuminate/container": "4.2.*",
        "filp/whoops": "~1.0"
    },
    "require-dev": {
        "phpunit/phpunit": "4.1.4",
        "mockery/mockery": "0.9.1",
        "phpdocumentor/phpdocumentor": "2.6.*",
        "phpspec/phpspec": "~2.0",
        "behat/behat": "2.4.*@stable",
        "behat/mink": "1.4@stable"
    },
    "autoload": {
        "psr-4": {
            "Nelissen\\LooseCI\\": "src/"
        },
        "classmap": [
            "application/core/",
            "application/libraries/",
            "application/models/",
            "application/controllers/"
        ]
    },
    "minimum-stability": "stable"
}

Wouldn't you be better off creating a way to allow people to override the creation of the controller? This way they could choose the container they want.

CodeIgniter.php? where i write tht in my project?