Expression is not allowed as field default value

问题:

I am trying to make $app available for the whole class.

First, I get:

"Expression is not allowed as field default value"

Second, on line 5, I get:

Unidentified variable $app

How can I achieve my goal?

class UserController extends XController
{
    var $app = Yii::app();;
    public function init()
    {
        $test = $app;

回答1:

You can not call a method to set a default value for a variable in PHP, even if it is a static method. Change it to be set in the constructor:

use Yii;

class UserController extends XController    
{
    var $app;

    function __construct() {
        $this->app =  = Yii::app();
    }

    public function init()    
    {
        $test = $this->app;
    } 
}

As a sidenote, you should not use the var keyword in PHP versions > 4, see this question for explanation.