OOP Pattern - Singleton: Enter Point



PHP Singleton Pattern Step By Step Tutorial - Part 1: In OOP, there are one or two resouces that are created and shared for entire application. Example, database connection. We don't need create a object every need connection. In this case, we use named Singleton pattern. A class based on singleton pattern properly instantiates and initializes one instance of the class and provide access to same object everytime. In this practice, we will create a singleton class that can certain method (can not access directly): 
<?php
class CarSingleton {
  
  var $instance = NULL;
	  
  function CarSingleton($fromGetInstance = false){
    if(M_E != $fromGetInstance){
	  trigger_error('do not instantiate 
	    directly');
	}
  }
  
  function &washCar(){
	if(!$this->instance){
	  $this->instance = new CarSingleton(M_E);
	  return $this->instance;
	}
  }

}

// try to test
$obj = CarSingleton::washCar();
$obj2 = new CarSingleton;
?>
We use M_E as key.

Series this article:
OOP Pattern - Singleton: Enter Point
OOP Pattern - Singleton: Using One Instance


Tag: oop, pattern, singleton Category: PHP Classes Post : February 19th 2008 Read: 1,192 Bookmark and Share

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