<?php

class Config {

    public static $factory = 1;

}

interface Product {

    public function getName();

}

abstract class AbstractFactory {

    public static function getFactory() {

        switch (Config::$factory) {

            case 1:

                return new FirstFactory();

            case 2:

                return new SecondFactory();

        }

        throw new Exception('Bad config');

    }

    abstract public function getProduct();

}

class FirstFactory extends AbstractFactory {

    public function getProduct() {

        return new FirstProduct();

    }

}

class FirstProduct implements Product {

    public function getName() {

        return 'The product from the first factory';

    }

}

class SecondFactory extends AbstractFactory {

    public function getProduct() {

        return new SecondProduct();

    }

}

class SecondProduct implements Product {

    public function getName() {

        return 'The product from second factory';

    }

}

$firstProduct = AbstractFactory::getFactory()->getProduct();

Config::$factory = 2;

$secondProduct = AbstractFactory::getFactory()->getProduct();

print_r($firstProduct->getName());

// The first product from the first factory

print_r($secondProduct->getName());

// Second product from second factory