There are discussions below regarding how to create a singleton that allows subclassing. It seems with get_called_class there is now a cleaner solution than what is discussed below, that does not require overriding a method per subclass.
e.g.
<?php
abstract class MySuperclass {
static private $instances = array();
static public function getInstance(): ACFBlock {
$className = get_called_class();
if (!isset(self::$instances[$className])) {
self::$instances[$className] = new static();
}
return self::$instances[$className];
}
private function __construct() {
}
}
class MySubclass extends MySuperclass {
}
MySubclass::getInstance();
