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Design Patterns with PHP

Time to go through some design patterns used wide in creating the applications.

Why do they exists, anyway?

Let's go to Observer pattern.See the example below, 

<?php

// Observer interface

interface Observer {

    public function update($message);

}

// Concrete Observers

class EmailSubscriber implements Observer {

    private $email;

    public function __construct($email) {

        $this->email = $email;

    }

    public function update($message) {

        echo "Email sent to {$this->email}: $message\n";

    }

}

class SMSSubscriber implements Observer {

    private $phone;


    public function __construct($phone) {

        $this->phone = $phone;

    }


    public function update($message) {

        echo "SMS sent to {$this->phone}: $message\n";

    }

}


// Subject

class NewsPublisher {

    private $subscribers = [];


    public function attach(Observer $observer) {

        $this->subscribers[] = $observer;

    }


    public function detach(Observer $observer) {

        $this->subscribers = array_filter(

            $this->subscribers,

            function($sub) use ($observer) {

                return $sub !== $observer;

            }

        );

    }


    public function notify($message) {

        foreach ($this->subscribers as $subscriber) {

            $subscriber->update($message);

        }

    }

}


// Usage

$publisher = new NewsPublisher();


$email1 = new EmailSubscriber("alice@example.com");

$email2 = new EmailSubscriber("bob@example.com");

$sms1 = new SMSSubscriber("+919999999999");


$publisher->attach($email1);

$publisher->attach($email2);

$publisher->attach($sms1);


// Send notification

$publisher->notify("🚨 Breaking News: Observer Pattern Enhanced!");


?>

 

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