Online PHP editor | output for t7qhR

<?php class Example { public int $nextNumber { get { $this->nextNumber ??= 0; return $this->nextNumber++; } set => throw new Error('Property Example::$nextNumber is read-only'); } } $foo = new Example; var_dump($foo->nextNumber, $foo->nextNumber, $foo->nextNumber); $foo->nextNumber = 42;