?? ????? ???? ??? ??? ?? ???? ?????. ??? ??? ???? ??? ????? ??????? ?? ????? ???? ? ??? ??? ????? ??? ????? ????? ???? ???? ??????. ??? ??? ?? ???? ??? ?? ? ????, PHP ???? ???? ? ??? ????? ???.

? ????? Observer ??? ??? ??? ???? ?? PHP ???????? ???? ??? ?????.

??? ???? ??????

??? ??? ?? ?? ??? ?? ??? ???? ?? ??? ?? ??? ????, ??? ??? ???? ?? ???? ?? ??? ??? ?? ???? ????? ? ????.

??? ???? ??? ????? ? ?? ??? ??? ????. Subject? ??? ????, ??? ???? ?? ??? ?? ??? ??? ? ?????. Observer? Subject? ?? ??? ???? ?? ???????. Subject? ??? ???? Observer? ??? ?? ?? ??? ???????.

PHP?? ??? ?? ??

PHP?? ??? ??? ???? ?? ?? ?????. PHP ?? ???? ?? ? ??? ??? ??? ? ????. ?? ???? ??? ??? ???? ??? ??? ????.

<?php

interface Subject {
  public function registerObserver(Observer $observer);
  public function removeObserver(Observer $observer);
  public function notifyObservers();
}

interface Observer {
  public function update();
}

class Product implements Subject {
  private $observers = array();
  private $name;

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

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

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

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

  public function setName($name) {
    $this->name = $name;
    $this->notifyObservers();
  }

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

class ProductObserver implements Observer {
  private $name;

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

  public function update($name) {
    echo $this->name . " has been updated to " . $name . "<br>";
  }
}

$product = new Product("Product A");
$observerA = new ProductObserver("Observer A");
$observerB = new ProductObserver("Observer B");

$product->registerObserver($observerA);
$product->registerObserver($observerB);

$product->setName("New Product");

$product->removeObserver($observerB);

$product->setName("Another Product");

? ????? Subject, Observer ? Product?? ? ?? ?????? ?????. Product ???? Subject ?????? ???? $observers ??? ?????. RegisterObserver(), RemoveObserver() ? informObservers() ???? ???? ??, ?? ? ??? ? ?????.

ProductObserver ???? Observer ?????? ???? ??? ??? ??? ? ??? ??? update() ???? ??????.

Product ????? ??? ? ?? ProductObserver ????? ???? ??? ? ????. Product? ??? ???? ?? setName() ???? ???? informObservers() ???? ???? ??? ?? ProductObserver ????? ??? ?? ???. ???? ??? ?? ?? ???, RemoveObserver() ???? ???? ???.

??

??? ??? ?? ?? ??? ?? ?? ???? ??? ? ??? ?? ?? ??? ??? ?????. PHP?? Observer ??? ???? ?? ?? ?? ??? ?????? ????? ?????. PHP ????? ??? ??????? ? ? ????? ???? ? ??? ?? Observer ??? ??? ?? ?? ?????.

? ??? PHP ????: ??? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!