class A {
    var $arr_of_b = array();
    function render() {
        render($this->arr_of_b);
    }
}

class B {
    function render() {
        echo("Class B\n");
    }
}

$foo = new A();
for ($i = 0; $i < 5; $i++) {
    $bar = new B();
    $foo->arr_of_b[] = $bar;
};

$foo->render();

Output:

Class B
Class B
Class B
Class B
Class B