PHP's SingleInstance

1<?PHP2     //Singleton: A class has only one object. 3 //Restrict the class from getting more objects, allowing only one object to be generated. , an object can accomplish all the functions of the object in order to save costs. This is the singleton pattern .4     5     /*6 function func () {7 static $name;//local static variable, calculated according to the function life cycle, the next call will continue to exist,8         }9         Ten class test{ One static $name;//belongs to the Class property.  A         } -  -     */ the  -     classmysqldb{ -         //declaring a static variable storage object -         Private Static $_instance; +  -         //the declaration is constructed as private and does not allow the outside new object +         Private function__construct () { A  at         } -  -         //given a class method that does not allow the class to be accessed directly from the class name -          Public Static functiongetinstance () { -  -             //To determine whether an object is instantiated in             if(!isset(Static::$_instance)) { -                 //if (! (static::$_instance instanceof Static)) Using the object transport symbol instanceof to make judgments to //Does not exist object, new object and returns to private static variable +                 Static::$_instance=New Static; -             } the  *             //return to static variable storage $             return Static::$_instance;Panax Notoginseng         } -  the         //in order to prevent the external cloning of the private magic method +         Private function__clone () { A  the         } +     } -  $  $     $dao= MySQLdb::getinstance (); -  -     Var_dump($dao); the  -     $dao 1= MySQLdb::getinstance ();Wuyi  the     Var_dump($dao 1); -  Wu     //$dao 2 = Clone $dao; Run Save/**/

PHP's SingleInstance