PHP 7.0.6 Released

    The SplSubject interface

    (PHP 5 >= 5.1.0, PHP 7)

    Introduction

    The SplSubject interface is used alongside SplObserver to implement the Observer Design Pattern.

    Interface synopsis

    SplSubject {
    /* Methods */
    abstract public void attach ( SplObserver $observer )
    abstract public void detach ( SplObserver $observer )
    abstract public void notify ( void )
    }

    Table of Contents

    User Contributed Notes

    przemyslaw dot szpiler at gmail dot com
    4 years ago
    <?php

    // Example implementation of Observer design pattern:

    class MyObserver1 implements SplObserver {
        public function     update(SplSubject $subject) {
            echo     __CLASS__ . ' - ' . $subject->getName();
        }
    }

    class     MyObserver2 implements SplObserver {
        public function     update(SplSubject $subject) {
            echo     __CLASS__ . ' - ' . $subject->getName();
        }
    }

    class     MySubject implements SplSubject {
        private     $_observers;
        private     $_name;

        public function     __construct($name) {
                $this->_observers = new SplObjectStorage();
                $this->_name = $name;
        }

        public function     attach(SplObserver $observer) {
                $this->_observers->attach($observer);
        }

        public function     detach(SplObserver $observer) {
                $this->_observers->detach($observer);
        }

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

        public function     getName() {
            return     $this->_name;
        }
    }

    $observer1 = new MyObserver1();
    $observer2 = new MyObserver2();

    $subject = new MySubject("test");

    $subject->attach($observer1);
    $subject->attach($observer2);
    $subject->notify();

    /*
    will output:

    MyObserver1 - test
    MyObserver2 - test
    */

    $subject->detach($observer2);
    $subject->notify();

    /*
    will output:

    MyObserver1 - test
    */

    ?>
    Anonymous
    2 years ago
    <?php
    class Observable implements SplSubject
    {
        private     $storage;

        function     __construct()
        {
                $this->storage = new SplObjectStorage();
        }

        function     attach(SplObserver $observer)
        {
                $this->storage->attach($observer);
        }

        function     detach(SplObserver $observer)
        {
                $this->storage->detach($observer);
        }

        function     notify()
        {
            foreach (    $this->storage as $obj) {
                    $obj->update($this);
            }
        }
            //...
    }

    abstract class     Observer implements SplObserver
    {
        private     $observable;

        function     __construct(Observable $observable)
        {
                $this->observable = $observable;
                $observable->attach($this);
        }

        function     update(SplSubject $subject)
        {
            if (    $subject === $this->observable) {
                    $this->doUpdate($subject);
            }
        }

        abstract function     doUpdate(Observable $observable);
    }

    class     ConcreteObserver extends Observer
    {
        function     doUpdate(Observable $observable)
        {
                //...
            }
    }

    $observable = new Observable();
    new     ConcreteObserver($observable);
    aiddroid at example dot com
    2 years ago
    /**
    * Subject,that who makes news
    */
    class Newspaper implements \SplSubject{
        private $name;
        private $observers = array();
        private $content;
       
        public function __construct($name) {
            $this->name = $name;
        }

        //add observer
        public function attach(\SplObserver $observer) {
            $this->observers[] = $observer;
        }
       
        //remove observer
        public function detach(\SplObserver $observer) {
           
            $key = array_search($observer,$this->observers, true);
            if($key){
                unset($this->observers[$key]);
            }
        }
       
        //set breakouts news
        public function breakOutNews($content) {
            $this->content = $content;
            $this->notify();
        }
       
        public function getContent() {
            return $this->content." (by {$this->name})";
        }
       
        //notify observers(or some of them)
        public function notify() {
            foreach ($this->observers as $value) {
                $value->update($this);
            }
        }
    }

    /**
    * Observer,that who recieves news
    */
    class Reader implements SplObserver{
        private $name;
       
        public function __construct($name) {
            $this->name = $name;
        }
       
        public function update(\SplSubject $subject) {
            echo $this->name.' is reading breakout news <b>'.$subject->getContent().'</b><br>';
        }
    }

    //classes test
    $newspaper = new Newspaper('Newyork Times');

    $allen = new Reader('Allen');
    $jim = new Reader('Jim');
    $linda = new Reader('Linda');

    //add reader
    $newspaper->attach($allen);
    $newspaper->attach($jim);
    $newspaper->attach($linda);

    //remove reader
    $newspaper->detach($linda);

    //set break outs
    $newspaper->breakOutNews('USA break down!');

    //=========output==========
    //Allen is reading breakout news USA break down! (by Newyork Times)
    //Jim is reading breakout news USA break down! (by Newyork Times)
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