1.8. Static Factory¶
1.8.1. Purpose¶
Similar to the AbstractFactory, this pattern is used to create series of
related or dependent objects. The difference between this and the
abstract factory pattern is that the static factory pattern uses just
one static method to create all types of objects it can create. It is
usually named factory
or build
.
1.8.2. UML Diagram¶

1.8.3. Code¶
You can also find this code on GitHub
StaticFactory.php
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | <?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
1 2 3 4 5 6 7 8 | <?php declare(strict_types=1);
namespace DesignPatterns\Creational\StaticFactory;
interface Formatter
{
public function format(string $input): string;
}
|
FormatString.php
1 2 3 4 5 6 7 8 9 10 11 | <?php declare(strict_types=1);
namespace DesignPatterns\Creational\StaticFactory;
class FormatString implements Formatter
{
public function format(string $input): string
{
return $input;
}
}
|
FormatNumber.php
1 2 3 4 5 6 7 8 9 10 11 | <?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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | <?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');
}
}
|