public function setLayoutVariableName($name)
    {
        $name = (string) $name;
        $name = trim($name);
        if (! preg_match('/^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*/', $name)) {
            throw new InvalidArgumentException('Invalid variable name');
        }
        $this->layoutVariableName = $name;
    }