2.11. Registry

2.11.1. Rôle

To implement a central storage for objects often used throughout the application, is typically implemented using an abstract class with only static methods (or using the Singleton pattern). Remember that this introduces global state, which should be avoided at all times! Instead implement it using Dependency Injection!

2.11.2. Diagramme UML

Alt Registry UML Diagram

2.11.3. Code

Vous pouvez également trouver ce code sur GitHub

Registry.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Registry;

use InvalidArgumentException;

abstract class Registry
{
    const LOGGER = 'logger';

    /**
     * this introduces global state in your application which can not be mocked up for testing
     * and is therefor considered an anti-pattern! Use dependency injection instead!
     *
     * @var Service[]
     */
    private static array $services = [];

    private static array $allowedKeys = [
        self::LOGGER,
    ];

    public static function set(string $key, Service $value)
    {
        if (!in_array($key, self::$allowedKeys)) {
            throw new InvalidArgumentException('Invalid key given');
        }

        self::$services[$key] = $value;
    }

    public static function get(string $key): Service
    {
        if (!in_array($key, self::$allowedKeys) || !isset(self::$services[$key])) {
            throw new InvalidArgumentException('Invalid key given');
        }

        return self::$services[$key];
    }
}

Service.php

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<?php

namespace DesignPatterns\Structural\Registry;

class Service
{

}

2.11.4. Test

Tests/RegistryTest.php

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<?php declare(strict_types=1);

namespace DesignPatterns\Structural\Registry\Tests;

use InvalidArgumentException;
use DesignPatterns\Structural\Registry\Registry;
use DesignPatterns\Structural\Registry\Service;
use PHPUnit\Framework\MockObject\MockObject;
use PHPUnit\Framework\TestCase;

class RegistryTest extends TestCase
{
    /**
     * @var Service
     */
    private MockObject $service;

    protected function setUp(): void
    {
        $this->service = $this->getMockBuilder(Service::class)->getMock();
    }

    public function testSetAndGetLogger()
    {
        Registry::set(Registry::LOGGER, $this->service);

        $this->assertSame($this->service, Registry::get(Registry::LOGGER));
    }

    public function testThrowsExceptionWhenTryingToSetInvalidKey()
    {
        $this->expectException(InvalidArgumentException::class);

        Registry::set('foobar', $this->service);
    }

    /**
     * notice @runInSeparateProcess here: without it, a previous test might have set it already and
     * testing would not be possible. That's why you should implement Dependency Injection where an
     * injected class may easily be replaced by a mockup
     *
     * @runInSeparateProcess
     */
    public function testThrowsExceptionWhenTryingToGetNotSetKey()
    {
        $this->expectException(InvalidArgumentException::class);

        Registry::get(Registry::LOGGER);
    }
}