PHP core design patterns and practices

PHP core design patterns and practices

Introduction:
Design patterns are commonly used problem-solving templates in software development. They provide a reusable solutions that help us follow best practices and good software design principles during the development process. As a widely used programming language, PHP also has many common and useful design patterns that can be used in core development. This article will introduce several common PHP design patterns and provide relevant code examples.

1. Singleton Pattern (Singleton)
The singleton pattern is a design pattern that only allows the creation of one instance. It is often used in scenarios where resources need to be shared or the number of objects created is limited. The following is a PHP implementation of singleton mode:

class Database
{
    private static $instance;

    private function __construct()
    {
        // 初始化数据库连接
    }

    public static function getInstance()
    {
        if (!self::$instance) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    // 其他数据库操作方法
}

$db = Database::getInstance();

2. Factory pattern (Factory)
Factory pattern is a design pattern that creates objects through factory classes. It hides the creation logic of objects. Makes the code more flexible and maintainable. The following is a simple PHP implementation of the factory pattern:

interface Product
{
    public function getName();
}

class ProductA implements Product
{
    public function getName()
    {
        return 'Product A';
    }
}

class ProductB implements Product
{
    public function getName()
    {
        return 'Product B';
    }
}

class ProductFactory
{
    public static function create($type)
    {
        switch ($type) {
            case 'A':
                return new ProductA();
            case 'B':
                return new ProductB();
            default:
                throw new Exception('Unsupported product type');
        }
    }
}

$product = ProductFactory::create('A');
echo $product->getName();

3. Observer Pattern (Observer)
The observer pattern is a one-to-many dependency relationship between objects. When the state of an object occurs When changes occur, all dependent objects will be notified. The following is a simple PHP implementation of the observer pattern:

interface Observer
{
    public function update($data);
}

class Subject
{
    private $observers = [];

    public function attach(Observer $observer)
    {
        $this->observers[] = $observer;
    }

    public function detach(Observer $observer)
    {
        $index = array_search($observer, $this->observers);
        if ($index !== false) {
            unset($this->observers[$index]);
        }
    }

    public function notify($data)
    {
        foreach ($this->observers as $observer) {
            $observer->update($data);
        }
    }
}

class ConcreteObserver implements Observer
{
    public function update($data)
    {
        echo 'Received data: ' . $data;
    }
}

$subject = new Subject();
$observer = new ConcreteObserver();
$subject->attach($observer);
$subject->notify('Hello World');

Conclusion:
The above are sample codes for several common PHP core design patterns, which can help us better organize and manage code, And follow good software design principles. In actual development, choosing appropriate design patterns based on specific needs and scenarios can improve code quality and maintainability. I hope this article will help you understand and apply PHP design patterns.

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