Factory Method Pattern

Das Factory Method Pattern definiert eine Schnittstelle zur Erzeugung von Objekten, verlagert aber die eigentliche Instanziierung in Unterklassen und läßt die Unterklassen entscheiden, welche konkreten Implementierungen verlangt werden.

Logger Interface

 

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

interface Logger
{
    public function log(string $message);
}

 

LoggerFactory Interface

 

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

interface LoggerFactory
{
    public function createLogger(): Logger;
}

 

Logger Implementation (FileLogger)

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

class FileLogger implements Logger
{
    private $filePath;

    public function __construct(string $filePath)
    {
        $this->filePath = $filePath;
    }

    public function log(string $message)
    {
        file_put_contents($this->filePath, $message . PHP_EOL, FILE_APPEND);
    }
}

 

Loggerimplementation (StOutLogger)

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

class StdoutLogger implements Logger
{
    public function log(string $message)
    {
        echo $message;
    }
}

 

LoggerFactory Implementation ( StdOutLoggerFactory)

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

class StdoutLoggerFactory implements LoggerFactory
{
    public function createLogger(): Logger
    {
        return new StdoutLogger();
    }
}

 

LoggerFactory Implementation (FileLoggerFactory)

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod;

class FileLoggerFactory implements LoggerFactory
{
    private $filePath;

    public function __construct(string $filePath)
    {
        $this->filePath = $filePath;
    }

    public function createLogger(): Logger
    {
        return new FileLogger($this->filePath);
    }
}

 

FactoryMethodTest

<?php declare(strict_types=1);

namespace DesignPatterns\Creational\FactoryMethod\Tests;

use DesignPatterns\Creational\FactoryMethod\FileLogger;
use DesignPatterns\Creational\FactoryMethod\FileLoggerFactory;
use DesignPatterns\Creational\FactoryMethod\StdoutLogger;
use DesignPatterns\Creational\FactoryMethod\StdoutLoggerFactory;
use PHPUnit\Framework\TestCase;

class FactoryMethodTest extends TestCase
{
    public function testCanCreateStdoutLogging()
    {
        $loggerFactory = new StdoutLoggerFactory();
        $logger = $loggerFactory->createLogger();

        $this->assertInstanceOf(StdoutLogger::class, $logger);
    }

    public function testCanCreateFileLogging()
    {
        $loggerFactory = new FileLoggerFactory(sys_get_temp_dir());
        $logger = $loggerFactory->createLogger();

        $this->assertInstanceOf(FileLogger::class, $logger);
    }
}