1.8. Static Factory (Statik Fabrika)

1.8.1. Amaç

Soyut Fabrika’ya (Abstract Factory) benzer biçimde, ilgili veya bağımlı nesneler serisi oluşturmak. Bu desen ile Soyut Fabrika deseni arasındaki fark, bu deseninoluşturabileceği her türlü nesneyi oluşturmak için yalnızca bir statik yöntem (method) kullanmasıdır. Yöntem ise genellikle factory, build veya create olarak adlandırılır.

1.8.2. UML Diyagramı

Alt StaticFactory UML Diagram

1.8.3. Kod

Bu kodu Github üzerinde de bulabilirsiniz.

StaticFactory.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\StaticFactory;

use InvalidArgumentException;

/**
 * Note1: Remember, static means global state which is evil because it can't be mocked for tests
 * Note2: Cannot be subclassed or mock-upped or have multiple different instances.
 */
final class StaticFactory
{
    public static function factory(string $type): Formatter
    {
        if ($type == 'number') {
            return new FormatNumber();
        } elseif ($type == 'string') {
            return new FormatString();
        }

        throw new InvalidArgumentException('Unknown format given');
    }
}

Formatter.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\StaticFactory;

interface Formatter
{
    public function format(string $input): string;
}

FormatString.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\StaticFactory;

class FormatString implements Formatter
{
    public function format(string $input): string
    {
        return $input;
    }
}

FormatNumber.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\StaticFactory;

class FormatNumber implements Formatter
{
    public function format(string $input): string
    {
        return number_format((int) $input);
    }
}

1.8.4. Test

Tests/StaticFactoryTest.php

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<?php

declare(strict_types=1);

namespace DesignPatterns\Creational\StaticFactory\Tests;

use InvalidArgumentException;
use DesignPatterns\Creational\StaticFactory\FormatNumber;
use DesignPatterns\Creational\StaticFactory\FormatString;
use DesignPatterns\Creational\StaticFactory\StaticFactory;
use PHPUnit\Framework\TestCase;

class StaticFactoryTest extends TestCase
{
    public function testCanCreateNumberFormatter()
    {
        $this->assertInstanceOf(FormatNumber::class, StaticFactory::factory('number'));
    }

    public function testCanCreateStringFormatter()
    {
        $this->assertInstanceOf(FormatString::class, StaticFactory::factory('string'));
    }

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

        StaticFactory::factory('object');
    }
}