備忘錄模式，在不破壞封裝物件的前提之下，提供物件一個「皇后殺手 第三爆彈：敗者成塵」的能力，物件在極度絕望的狀態下，把當前物件炸光光，並令時間往前倒退至上一個時空紀錄點的設計模式，跟吉良吉影的不同點在於命運會跟著被改變，被破壞的東西會恢復原狀。
為了讓大頭菜有爆掉並往前倒退至上一個時空紀錄點的功能，這次我們要先實作備忘錄模式，用來儲存大頭菜的時空狀態，好讓大頭菜可以回到過去。
大頭菜：「キラークイーン、バイツ・ザ・ダスト！」
Memento.php
/**
* Class Memento.
*/
class Memento
{
/**
* @var int
*/
protected int $price;
/**
* @var int
*/
protected int $count;
/**
* Memento constructor.
*
* @param int $price
* @param int $count
*/
public function __construct(int $price, int $count)
{
$this->price = $price;
$this->count = $count;
}
/**
* @return int
*/
public function getPrice(): int
{
return $this->price;
}
/**
* @return int
*/
public function getCount(): int
{
return $this->count;
}
}接下來要實作擁有第三爆彈的大頭菜，除了以往所擁有的資訊、方法以外，這次要提供儲存、載入的功能，讓大頭菜能在任意的時空點進行儲存，並且在自己被逼到極限時，按下第三爆彈穿越時空回到過去。
大頭菜：「到極限了，就是現在，按下去！」
Turnips.php
/**
* Class Turnips.
*/
class Turnips
{
/**
* @var int
*/
protected int $price;
/**
* @var int
*/
protected int $count;
/**
* Turnips constructor.
*
* @param int $price
* @param int $count
*/
public function __construct(int $price, int $count)
{
$this->price = $price;
$this->count = $count;
}
/**
* @return Memento
*/
public function saveToMemento(): Memento
{
return new Memento($this->price, $this->count);
}
/**
* @param Memento $memento
*/
public function restoreFromMemento(Memento $memento)
{
$this->price = $memento->getPrice();
$this->count = $memento->getCount();
}
/**
* @return int
*/
public function getPrice(): int
{
return $this->price;
}
/**
* @return int
*/
public function getCount(): int
{
return $this->count;
}
/**
* @return int
*/
public function setPrice(int $price)
{
$this->price = $price;
}
/**
* @return int
*/
public function setCount(int $count)
{
$this->count = $count;
}
/**
* @return int
*/
public function calculatePrice(): int
{
return $this->getPrice() * $this->getCount();
}
}接下來我們要替第三爆彈模式測試一下，要讓大頭菜真的儲存某個時空點，並且按下爆彈炸毀當前物件，然後飛躍時空回到過去。
MementoPatternTest.php
/**
* Class MementoPatternTest.
*/
class MementoPatternTest extends TestCase
{
/**
* @test
*/
public function test_bites_the_dust()
{
$turnips = new Turnips(100, 40);
$this->assertEquals(4000, $turnips->calculatePrice());
/**
* 儲存當前時空
*/
$memento = $turnips->saveToMemento();
$newPrice = random_int(0, 600);
$turnips->setPrice($newPrice);
$this->assertEquals($newPrice * 40, $turnips->calculatePrice());
/**
* 到極限了，就是現在，按下去！
*/
$turnips->restoreFromMemento($memento);
$this->assertEquals(4000, $turnips->calculatePrice());
}
}最後測試的執行結果會獲得如下：
PHPUnit Pretty Result Printer 0.28.0 by Codedungeon and contributors.
==> Configuration: ~/php-design-pattern/vendor/codedungeon/phpunit-result-printer/src/phpunit-printer.yml
PHPUnit 9.2.6 by Sebastian Bergmann and contributors.
==> ...fResponsibilitiesTest ✔ ✔ ✔
==> CommandPatternTest ✔
==> IteratorPatternTest ✔ ✔ ✔ ✔
==> MediatorPatternTest ✔ ✔ ✔
==> MementoPatternTest ✔
==> AbstractFactoryTest ✔ ✔ ✔ ✔
==> BuilderPatternTest ✔ ✔ ✔ ✔
==> FactoryMethodTest ✔ ✔ ✔ ✔
==> PoolPatternTest ✔ ✔
==> PrototypePatternTest ✔ ✔
==> SimpleFactoryTest ✔ ✔ ✔ ✔
==> SingletonPatternTest ✔
==> StaticFactoryTest ✔ ✔ ✔ ✔ ✔
==> AdapterPatternTest ✔ ✔
==> BridgePatternTest ✔ ✔ ✔
==> CompositePatternTest ✔ ✔ ✔
==> DataMapperTest ✔ ✔
==> DecoratorPatternTest ✔ ✔
==> DependencyInjectionTest ✔ ✔ ✔
==> FacadePatternTest ✔
==> FluentInterfaceTest ✔
==> FlyweightPatternTest ✔
==> ProxyPatternTest ✔ ✔
==> RegistryPatternTest ✔ ✔ ✔ ✔ ✔
Time: 00:00.105, Memory: 6.00 MB
OK (63 tests, 132 assertions)