php单例型(singleton pattern)

搞定，吃饭

<?php
/*
The purpose of singleton pattern is to restrict instantiation of class to a single object. It
is implemented by creating a method within the class that creates a new instance of
that class if one does not exist. If an object instance already exists, the method simply
returns a reference to an existing object.
*/class Logger {private static $instance;public static function getInstance() {if (!isset(self::$instance)) {self::$instance = new self;}return self::$instance;}public function logNotice($msg) {return 'logNotice: ' . $msg . '<br/>';}public function logWaring($msg) {return 'logWaring: ' . $msg . '<br/>';}public function logError($msg) {return 'logError: ' . $msg . '<br/>';}
}echo Logger::getInstance()->logNotice('test-log-notice');
echo Logger::getInstance()->logWaring('test-log-waring');
echo Logger::getInstance()->logError('test-log-error');
?>