SingletonSample

gistfile1.php

<?php
class SingletonSample {
        /**
	 * member variable;
	 * */
	private $id;
	
	/**
	 * constructor
	 * 
	 * creating a hashed value based on date as ID.  
	 * prevent you from creating the instance,
	 * cause adding private prefix to the construct function.
	 * */
	private function __construct() {
		$this->id = md5(date('r').mt_rand());
	}
	
	/**
	 * get instance
	 * */

	public static function getInstance() {
        /**
         * a variable that keeps the sole instance.
         */
        static $instance;

        if (!isset($instance)) {
            $instance = new SingletonSample();
            echo 'a SingletonSample instance was created !';
        }
        return $instance;
	}
	
	/**
	 * return ID 
	 * */
	public function getID() {
		return $this->id;
	}
	
	/**
	 * don't allow you to clone the instance.
	 * */	
	public final function __clone() {
		throw new RuntimeException('Clone is not allowed against ');
	}
	
}