Design Patterns (singleton)

Source: Internet
Author: User

Singleton mode is the simplest design mode,


Ensure that a class has only one instance and provides a global access point to access it.


There can only be one instance and the customer can access it from a well-known access point.

When this unique instance should be extensible by subclasses, and the customer should be able to use an extended instance without changing the code.

Schematic diagram:

Code implementation:

<?phpclass Singleton {//     private static $_instance = Array ();    private static $_instance = ";    Public $num = 0;    public static function getinstance () {        if (empty (self::$_instance)) {            self::$_instance = new self ();        }         if (Isset (self::$_instance[])) {//             self::$_instance = new self ();/         }        return self::$_instance;    } public        function sayname ($name = ' Zhangsan ') {        echo $name, "<br/>";        $this->num++;    }    Public Function Saynum () {        echo $this->num, "<br/>";    }}      $test 1 = singleton::getinstance (); $test 1->sayname ();       Zhangsn$test1->saynum ();  1$test2 = Singleton::getinstance (); $test 2->sayname (' Lisi ');      Lisi$test2->saynum (); 2


Design Patterns (singleton)

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