Online PHP editor | output for 02vqB

<?php final class DemoFile { /** * @var array{ * cache: array{directory: null} * } */ protected array $config = [ 'cache' => [ 'directory' => null, ], ]; public function getCacheDirectory(): ?string { $dir = $this->config['cache']['directory'] ?? null; \assert(\is_string($dir) || $dir === null, 'Invalid cache directory.'); return $dir; } } $demo = new DemoFile(); var_dump($demo->getCacheDirectory());