1.3. 팩토리 메서드 (Factory Method)

1.3.1. 사용 목적

단순팩토리(SimpleFactory)의 좋은점은 서브클래스가 객체를 여러 방법으로 구현할 수 있다는 것 입니다.

간단한 예로는, 이 추상 클래스는 인터페이스가 될 수 있다는 것입니다.

이 패턴은 “real” 디자인 패턴 입니다. 왜냐하면 S.O.L.I.D 원리에서 “D”에 해당하는, 일명 “역 의존성 원리(Dependency Inversion Principle)”를 달성해야 하기 때문입니다.

이 말은 FactoryMethod(코드에 언급된)클래스는 구체적인 클래스가 아닌, 추상화에 따른다는 것입니다. 이것은 단순팩토리나 정적팩토리에 비하면 진짜 기술입니다.

1.3.2. UML 다이어그램

1.3.3. 코드

코드는 또한 GitHub 에서 볼 수 있습니다.

FactoryMethod.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * class FactoryMethod
 */
abstract class FactoryMethod
{

    const CHEAP = 1;
    const FAST = 2;

    /**
     * The children of the class must implement this method
     *
     * Sometimes this method can be public to get "raw" object
     *
     * @param string $type a generic type
     *
     * @return VehicleInterface a new vehicle
     */
    abstract protected function createVehicle($type);

    /**
     * Creates a new vehicle
     *
     * @param int $type
     *
     * @return VehicleInterface a new vehicle
     */
    public function create($type)
    {
        $obj = $this->createVehicle($type);
        $obj->setColor("#f00");

        return $obj;
    }
}

ItalianFactory.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * ItalianFactory is vehicle factory in Italy
 */
class ItalianFactory extends FactoryMethod
{
    /**
     * {@inheritdoc}
     */
    protected function createVehicle($type)
    {
        switch ($type) {
            case parent::CHEAP:
                return new Bicycle();
                break;
            case parent::FAST:
                return new Ferrari();
                break;
            default:
                throw new \InvalidArgumentException("$type is not a valid vehicle");
        }
    }
}

GermanFactory.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * GermanFactory is a vehicle factory in Germany
 */
class GermanFactory extends FactoryMethod
{
    /**
     * {@inheritdoc}
     */
    protected function createVehicle($type)
    {
        switch ($type) {
            case parent::CHEAP:
                return new Bicycle();
                break;
            case parent::FAST:
                $obj = new Porsche();
                // we can specialize the way we want some concrete Vehicle since
                // we know the class
                $obj->addTuningAMG();

                return $obj;
                break;
            default:
                throw new \InvalidArgumentException("$type is not a valid vehicle");
        }
    }
}

VehicleInterface.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * VehicleInterface is a contract for a vehicle
 */
interface VehicleInterface
{
    /**
     * sets the color of the vehicle
     *
     * @param string $rgb
     */
    public function setColor($rgb);
}

Porsche.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * Porsche is a german car
 */
class Porsche implements VehicleInterface
{
    /**
     * @var string
     */
    protected $color;

    /**
     * @param string $rgb
     */
    public function setColor($rgb)
    {
        $this->color = $rgb;
    }

    /**
     * although tuning by AMG is only offered for Mercedes Cars,
     * this is a valid coding example ...
     */
    public function addTuningAMG()
    {
    }
}

Bicycle.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * Bicycle is a bicycle
 */
class Bicycle implements VehicleInterface
{
    /**
     * @var string
     */
    protected $color;

    /**
     * sets the color of the bicycle
     *
     * @param string $rgb
     */
    public function setColor($rgb)
    {
        $this->color = $rgb;
    }
}

Ferrari.php

<?php

namespace DesignPatterns\Creational\FactoryMethod;

/**
 * Ferrari is a italian car
 */
class Ferrari implements VehicleInterface
{
    /**
     * @var string
     */
    protected $color;

    /**
     * @param string $rgb
     */
    public function setColor($rgb)
    {
        $this->color = $rgb;
    }
}

1.3.4. 테스트

Tests/FactoryMethodTest.php

<?php

namespace DesignPatterns\Creational\FactoryMethod\Tests;

use DesignPatterns\Creational\FactoryMethod\FactoryMethod;
use DesignPatterns\Creational\FactoryMethod\GermanFactory;
use DesignPatterns\Creational\FactoryMethod\ItalianFactory;

/**
 * FactoryMethodTest tests the factory method pattern
 */
class FactoryMethodTest extends \PHPUnit_Framework_TestCase
{

    protected $type = array(
        FactoryMethod::CHEAP,
        FactoryMethod::FAST
    );

    public function getShop()
    {
        return array(
            array(new GermanFactory()),
            array(new ItalianFactory())
        );
    }

    /**
     * @dataProvider getShop
     */
    public function testCreation(FactoryMethod $shop)
    {
        // this test method acts as a client for the factory. We don't care
        // about the factory, all we know is it can produce vehicle
        foreach ($this->type as $oneType) {
            $vehicle = $shop->create($oneType);
            $this->assertInstanceOf('DesignPatterns\Creational\FactoryMethod\VehicleInterface', $vehicle);
        }
    }

    /**
     * @dataProvider getShop
     * @expectedException \InvalidArgumentException
     * @expectedExceptionMessage spaceship is not a valid vehicle
     */
    public function testUnknownType(FactoryMethod $shop)
    {
        $shop->create('spaceship');
    }
}