目的

避免以标准方式（new Foo()）创建对象的成本，而是创建一个原型（prototype）并克隆它。

例子

• 大量数据（例如：通过 ORM 在数据库中创建百万行数据。）

UML 图

代码

BookPrototype.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Prototype;

abstract class BookPrototype
{
    protected string $title;
    protected string $category;

    abstract public function __clone();

    public function getTitle(): string
    {
        return $this->title;
    }

    public function setTitle(string $title): void
    {
        $this->title = $title;
    }
}

BarBookPrototype.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Prototype;

class BarBookPrototype extends BookPrototype
{
    protected string $category = 'Bar';

    public function __clone()
    {
    }
}

FooBookPrototype.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Prototype;

class FooBookPrototype extends BookPrototype
{
    protected string $category = 'Foo';

    public function __clone()
    {
    }
}

测试

Tests/PrototypeTest.php

<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\Prototype\Tests;

use DesignPatterns\Creational\Prototype\BarBookPrototype;
use DesignPatterns\Creational\Prototype\FooBookPrototype;
use PHPUnit\Framework\TestCase;

class PrototypeTest extends TestCase
{
    public function testCanGetFooBook()
    {
        $fooPrototype = new FooBookPrototype();
        $barPrototype = new BarBookPrototype();

        for ($i = 0; $i < 10; $i++) {
            $book = clone $fooPrototype;
            $book->setTitle('Foo Book No ' . $i);
            $this->assertInstanceOf(FooBookPrototype::class, $book);
        }

        for ($i = 0; $i < 5; $i++) {
            $book = clone $barPrototype;
            $book->setTitle('Bar Book No ' . $i);
            $this->assertInstanceOf(BarBookPrototype::class, $book);
        }
    }
}