Implementation of PHP5+ standard function library observer_PHP tutorial

Implementation of PHP5+ standard function library observer

The implementation of PHP's observer design pattern is relatively simple, but the PHP5+ version already has standard library support, and we only need to simply inherit and implement it.

Observer: Implements the standard interface class library SplSubject. One registration method: attach, one deregistration method: detach. A notification method: nofity.

<?php

class TSPLSubject implements SplSubject{

	 private $observers, $value;

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

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

	 public function detach(SplObserver $observer){
		if($idx = array_search($observer, $this->observers,true)) {
			unset($this->observers[$idx]);
		}
	 }
	 
    /**
	 *
	 * Notify observers one by one (main entry)
	 *
	 * @param none
	 * @return none
	 */
	 public function notify(){
		foreach($this->observers as $observer){
			$observer->update($this);
		}
	 }

	 public function setValue($value){
		$this->value = $value;
		//$this->notify();
	 }

	 public function getValue(){
		 return $this->value;
	 }
}

Observed: implements the standard interface class library SplObserver. An update method.

<?php

class TSPLObserver implements SplObserver{
	 public function update(SplSubject $subject){
		 echo &#39;The new state of subject &#39; , nl2br("\r\n");
//		 echo &#39;The new state of subject &#39;.$subject->getValue();
	 }
}

<?php

class TSPLObserver1 implements SplObserver{
	 public function update(SplSubject $subject){
		 echo &#39;The new state of subject one &#39; , nl2br("\r\n");
//		 echo &#39;The new state of subject &#39;.$subject->getValue();
	 }
}

Test call (in the same directory):

<?php

function __autoload($classname) { 
  require_once ($classname . ".php"); 
}

$subject = new TSPLSubject();
$subject->attach(new TSPLObserver());
$observer1 = new TSPLObserver1();
$subject->attach($observer1);
//$subject->attach(new TSPLObserver2());
//$subject->detach($observer1);

$subject->notify();

exit();

Output:

>php basic.php
The new state of subject

The new state of subject one

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