note 90424 added to language.oop5.patterns

in reply to marshall dot mattingly at NOSPAM dot gmail dot com This is an example of a Singleton in php 5.2.8 <?php // php version: 5.2.8 //---------------------------- /** * class Singleton * */ class Singleton { protected static $_instance = NULL; // visible to all subclasses protected static $e = ''; // visible to all subclasses private function __clone(){} protected function __construct(){} public static function GetInstance() { if (is_null(self::$_instance) or !self::$_instance instanceof self) self::$_instance = new self(); return self::$_instance; } public static function SetMsg( $msg = '' ) { self::$e = $msg; } public static function GetMsg() { return self::$e; } } /** * class Extension * */ class Extension extends Singleton { /** * Throws a Fatal Error, because this function is never called in this context * but of the Singleton's which hasn't this function implemented ! */ public static function Call() { return 'Extension: class '.__CLASS__.' was called!'; } } // Test // #1 instance $a = Singleton::GetInstance(); $a->SetMsg('hi there! This is instance #1'); // Set the message $ext = Extension::GetInstance(); $ext->SetMsg('hey'); // change message. This change is visible on all instances // #2 instance $b = Singleton::GetInstance(); // change the message again? Will overwrite $ext->SetMsg('hey'); //$b->SetMsg('hi there! This is instance #2'); // #3 instance $c = Singleton::GetInstance(); echo '$a instance: '.$a->GetMsg().'<br/>'; echo '$b instance: '.$b->GetMsg().'<br/>'; echo '$c instance: '.$c->GetMsg().'<br/>'; echo '$ext instance: '.$ext->GetMsg().'<br/>'; echo '$ext instance call: '.$ext->Call().'<br/>'; /* outputs: */ /* $a instance: hey $b instance: hey $c instance: hey $ext instance: hey Fatal error: Call to undefined method Singleton::Call() in G:\phproot\DesignPatterns\Singleton\class.Singleton.php on line 80 */ ?> As you can see it works as expected, and the protected properties are visible to subclasses. I wonder if this really has been changed in php 5.3.0... hmmm.. ---- Server IP: 69.147.83.197 Probable Submitter: 95.76.10.140 ---- Manual Page -- http://www.php.net/manual/en/language.oop5.patterns.php Edit -- https://master.php.net/note/edit/90424 Del: integrated -- https://master.php.net/note/delete/90424/integrated Del: useless -- https://master.php.net/note/delete/90424/useless Del: bad code -- https://master.php.net/note/delete/90424/bad+code Del: spam -- https://master.php.net/note/delete/90424/spam Del: non-english -- https://master.php.net/note/delete/90424/non-english Del: in docs -- https://master.php.net/note/delete/90424/in+docs Del: other reasons-- https://master.php.net/note/delete/90424 Reject -- https://master.php.net/note/reject/90424 Search -- https://master.php.net/manage/user-notes.php