GenericSingleton in PHP

GenericSingleton.php

<?php

class A1 {

    /**
     * @var array
     */
    private static $instanceDictionary = array();

    /**
     * @return self
     */
    public static function getInstance()
    {
        $calledClass = get_called_class();
        $dictionary = self::$instanceDictionary;
        if(!array_key_exists($calledClass, $dictionary)) {
            
            $reflectionClass = new \ReflectionClass($calledClass);
            $reflectionMethod = $reflectionClass->getMethod('createInstance');
            $reflectionMethod->setAccessible(true);
            $dictionary[$calledClass] = $reflectionMethod->invokeArgs(
                null, func_get_args()
            );
            
            self::$instanceDictionary = $dictionary;
        }

        return $dictionary[$calledClass];
    }

    /**
     * @return self
     */
    public static function createInstance()
    {
        var_dump('create '.get_called_class());
        $className = get_called_class();

        return new $className();
    }

    public $x1 = 10;
    
    /**
     *  thx. to radmen
     **/
    protected function __construct()
    {
    }
}

class A2 extends A1 {

    /**
     * Just to fix type hinting issues. otherwiese my PHPStorm ide assumes it to be A1 type
     * @return self
     */
    public static function getInstance()
    {
        return parent::getInstance();
    }

    public $x2 = 10;
}

class A3 extends A2 {
    
    /**
     * Just to fix type hinting issues. otherwiese my PHPStorm ide assumes it to be A1 type
     * @return self
     */
    public static function getInstance()
    {
        return parent::getInstance();
    }
    public $x3 = 10;
    public $x1 = 5;

}



$a1 = A1::getInstance();
$a2 = A2::getInstance();
$a3 = A3::getInstance();

$a1 = A1::getInstance();
$a2 = A2::getInstance();
$a3 = A3::getInstance();

var_dump($a1);
var_dump($a2);
var_dump($a3);

exit;

@radmen I re-implemented the getInstance() method in child classes to solve ide type hinting issues. Thats the only reason. For php itself you are right. There is no need to override that method within child classes.

Btw, same type hinting issue on inheritance in conjunction with chaining/fluid interfaces.

good job