类中的变量（其值来自另一个类）不可用于方法[关闭]

I'm new to OOP so there's probably something fundamental I'm missing here. In the Foo class, the $this->user_group variable is not available to the bar() method. Why is that? And is there a less messy way to get these classes to all talk to each other than including the $DB (and others) every instantiation (this gets hairier with my actual code, which has many more classes). Here's an example:

class Foo {
    private $Auth, $user_group;

    function __construct($DB) {
        $this->Auth       = new Auth($DB);
        $this->user_group = $this->Auth->get_user_permissions_group();
        // ("echo $this->user_group;" here will output the correct value)
    }

    public function bar() {
        // ("echo $this->user_group;" here will output nothing)
        return ($this->user_group > 1 ? 'cool!' : 'not cool!');
    }
} 

class Auth {
    private $DB;

    function __construct($DB) {
        $this->DB = $DB;
    }

    public function get_user_permissions_group() {
        $result = $this->DB->query('return user permissions level from DB');
        return $result; // int, 1-3
    }
}


$DB = new Database();
$Foo = new Foo($DB);
echo $Foo->bar();

user_group should be visible in the bar function. Are you sure you didn't mess up your curly brace blocks somewhere in the code and that Auth->get_user_permissions_group() returns an integer?

You can double check the following code on this site. It's working fine for me.

class Foo {
    private $user_group;

    function __construct($group) {
        $this->user_group = $group;
    }

    public function bar() {
        return ($this->user_group > 1 ? 'cool!' : 'not cool!');
    }
} 


$Foo = new Foo(3);
echo $Foo->bar();