Private class instantinators

instantinators.php

<?php
/**
 * Sealed class can not be created directly
 */
class Seal
{
    private function __construct()
    {
        // private ctor prevents from direct creation of instance
    }
}

#1 Via traditional reflection without constructor
$refClass = new ReflectionClass(Seal::class);
$instance = $refClass->newInstanceWithoutConstructor();
var_dump($instance);


#2 Via closure binding to the sealed class
$instantinator = function () {
    return new static;
};
$instantinator = $instantinator->bindTo(null, Seal::class);
$instance      = $instantinator();
var_dump($instance);

#3 Via unserialize hack
$instance = unserialize(sprintf('O:%d:"%s":0:{}', strlen(Seal::class), Seal::class));
var_dump($instance);

#4 Via PDO, requires pdo_sqlite which is typically available, can be pdo_mysql, then change: SELECT "test" FROM DUAL
if (phpversion('pdo_sqlite')) {
    $database = new PDO('sqlite::memory:');
    $result   = $database->query('SELECT "test" as field1'); // We can even initialize properties in the object
    $instance = $result->fetchObject(Seal::class);
    var_dump($instance);
}

#5 Via STOMP, requires php_stomp to be loaded
if (phpversion('stomp')) {
    $connection = new Stomp(/* connection args */);
    $connection->subscribe('Test');
    $connection->readFrame(Seal::class);
}

https://3v4l.org/cSfPS