public function cmdDeleteProductClass()
    {
        $id = $this->getParam(0);

        $result = null;

        if (isset($id)) {

            if (empty($id) || !is_numeric($id)) {
                $this->errorAndExit($this->text('Invalid argument'));
            }

            $result = $this->product_class->delete($id);

        } else if ($this->getParam('all')) {

            $deleted = $count = 0;
            foreach ($this->product_class->getList() as $item) {
                $count++;
                $deleted += (int) $this->product_class->delete($item['product_class_id']);
            }

            $result = $count && $count == $deleted;

        } else {
            $this->errorAndExit($this->text('Invalid command'));
        }

        if (empty($result)) {
            $this->errorAndExit($this->text('Unexpected result'));
        }

        $this->output();
    }