Factory and DI example

factory_di

<?php
class Car
{
    protected $power;
    protected $doors;

    public static function factory($type, Engine $engine, Transmission $transmission)
    {
        $instance = null;
        switch ($type) {
            case 2:
                $instance = new Sedan($engine, $transmission);
                break;
            case 4:
                $instance = new Crossover($engine, $transmission);
                break;
            default:
                throw new Exception('Invalid type');
        }

        return $instance;
    }

    public function __construct(Engine $engine, Transmission $transmission)
    {
        $this->engine       = $engine;
        $this->transmission = $transmission;
    }
}

class Sedan extends Car
{
    // implementation
}

class Crossover extends Car
{
    // implementation
}