Inherited getInstance()

inherited_getinstance.php

<?php
class A
{
    protected static $instance = array();

    protected function A()
    {
    }


    public static function getInstance()
    {
        $class = get_called_class();

        if ( !isset(self::$instance[$class]) ) {
            self::$instance[$class] = new $class();

        }

        return self::$instance[$class];

    }
}

class B extends A
{
    protected function B()
    {

    }

}

echo get_class(A::getInstance());
echo "\n";
echo get_class(B::getInstance());
echo "\n";