PHP Single-instance mode

How is the singleton mode written?

4 steps are generally required to implement a single case

First: A static variable saves the current instance

private static $_instance;

Second: Private constructors prevent external instantiation of objects

Private Function__construct () {}

Third: Private cloning function to prevent the external cloning of objects

Private Function __clone () {}

IV: Static method, single access entry with uniform

public static function getinstance () {

if (Is_null (self::$_instance) | | isset (self::$_instance)) {

Self::$_instance=new self ();

}

return self::$_instance;

}

PHP Single-instance mode