configuration = $config; } public function getDsn(): string { // this is just for the sake of demonstration, not a real DSN // notice that only the injected config is used here, so there is // a real separation of concerns here return sprintf( '%s:%s@%s:%d', $this->configuration->getUsername(), $this->configuration->getPassword(), $this->configuration->getHost(), $this->configuration->getPort() ); } }