Most useful design pattern in PHP

2 min readFeb 16, 2023

There are many design patterns that can be used in PHP, but here are some of the most commonly used ones:

Singleton pattern:

This pattern restricts the instantiation of a class to a single object. It can be useful when you need to ensure that only one instance of a particular object is available throughout the application. For example, a database connection object.

Factory pattern:

This pattern provides an interface for creating objects without specifying the exact class of object that will be created. It allows you to decouple object creation from the rest of the code. For example, you could use a factory to create different types of payment objects, such as CreditCardPayment, PayPalPayment, or BitcoinPayment.

Observer pattern:

This pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. For example, a news website might use the observer pattern to notify users when a new article is published.

Here are some examples of each pattern in PHP:

1. Singleton pattern:

class Database {
    private static $instance;

    private function __construct() {
        // Private constructor to prevent direct instantiation
    }    public static function getInstance() {
        if (!self::$instance) {
            self::$instance = new Database();
        }        return self::$instance;
    }    public function query($sql) {
        // Database query code here
    }
}

2. Factory pattern:

interface PaymentMethod {
    public function processPayment($amount);
}

class CreditCardPayment implements PaymentMethod {
    public function processPayment($amount) {
        // Credit card payment code here
    }
}class PayPalPayment implements PaymentMethod {
    public function processPayment($amount) {
        // PayPal payment code here
    }
}class PaymentFactory {
    public static function createPayment($method) {
        switch ($method) {
            case 'credit_card':
                return new CreditCardPayment();
            case 'paypal':
                return new PayPalPayment();
            default:
                throw new Exception("Invalid payment method");
        }
    }
}

3. Observer pattern:

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

interface Subject {
    public function attach(Observer $observer);
    public function detach(Observer $observer);
    public function notify($data);
}class NewsWebsite implements 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) {
            array_splice($this->observers, $index, 1);
        }
    }    public function notify($data) {
        foreach ($this->observers as $observer) {
            $observer->update($data);
        }
    }    public function publishArticle($article) {
        // Code to publish article here
        $this->notify($article);
    }
}class User implements Observer {
    public function update($data) {
        // Code to notify user of new article here

Happy coding