定义变量时PHP语法错误

I am using Yii-user module for authentication and I am trying to filter some output with user id.

class WordsController extends Controller
{
...
     private $userObject = Yii::app()->getModule('user')->user();
...
}

This code shows this error:

Parse error: syntax error, unexpected '(', expecting ',' or ';' in ...

I don't have an idea what is wrong.

Here is the link of the module https://code.google.com/p/yii-user/wiki/API

Your declaration of the class property is invalid. This usage is not allowed by PHP.

private $userObject = Yii::app()->getModule('user')->user();  // Invalid usage

To get around this, use the following : class WordsController extends Controller

{
...
    private $userObject = null;

    public function init()
    {
       $this->userObject = Yii::app()->getModule('user')->user();
    }
...
}

See the PHP manual for more details: http://www.php.net/manual/en/language.oop5.properties.php