将一个类的实例传递给另一个类以使用其变量

我正在尝试将我的生成器类的一个实例传递给另一个类以使用某些变量。生成器类实例工作正常，但是当我将其传递给另一个（选择策略）类时，它似乎根本没有传递变量。我不确定我做错了什么 - 我在调用的函数上使用var_dump来检查它给了我什么，但它只是空白的。

功能

class Generator 
{
    //properties for self
    private $s_charge;
    public $connection;
    public $task_priority;
    public $fog_mode = true;
    public $nodes = array();
    public $type;
    public function generateNodesSpecs() {
        $node = array();
        for ($i = 0; $i < 100; $i++) {
            $charge1 = mt_rand(30,100);
            $node['charge'] = $charge1;
            //array_push($node, $charge1);
            $hops = mt_rand(0,4);
            $node['hops'] = $hops;
            //array_push($node, $hops);
            $resource1 = mt_rand(0,100);
            if ($resource1 <= 50) {
                if ($resource1 <=10){
                    $node['connection'] = '4G';
                    //array_push($node, '4G');
                }
                else {
                    $node['connection'] = '3G';
                    //array_push($node, '3G');
                }
            }
            else if ($resource1 > 50 && $resource1 <= 60) {
                $node['connection'] = 'WiFi';
                //array_push($node, 'WiFi');
            }
            else {
            }
            $resource2 = mt_rand(0,100);
            if ($resource2 <=60) {
                $node['additional'] = 'CPU';
                //array_push($node, 'CPU');
            }
            else {
            $node['additional'] = 'none';
            }
            $this->nodes[] = $node;
            //array_push($nodes, $node);
            unset($node);
        }
    //compare which get the resources
    //var_dump($this->nodes[0]); 
    }
class SelectStrategy {
//take in generator class instance
    private $generator;
    private $priority;
    private $size;
    private $slaves = array();
    private $found_slave = null; //will hold item with max val;
    public function __construct($generator) {
        $this->generator = $generator;
    }
private function selectSlaves() {
        $max = -9999999; //will hold max val
        foreach($this->generator->nodes as $k=>$v)
        {
            if($v['charge']>$max)
            {
               $max = $v['charge'];
               $this->found_slave = $v;
            }
        }
        var_dump($this->found_slave); 
} 
}

和类/函数调用

$generator = new Generator();
$generator->generateNodesSpecs();
$select_strategy = new SelectStrategy($generator);
$select_strategy->selectSlaves();

$this->generator->nodes是 2D 数组