Constructores

 <?php

        class A {

            public $elementos = [];

            public function __construct() {
                for ($i = 0; $i < 10; $i++) {
                    $this->elementos[] = $i;
                }
            }
          

        }

        class B {

            public $elementos = [];

            public function __construct($num=10) {
                for ($i = 0; $i < $num; $i++) {
                    $this->elementos[] = $i;
                }
            }

        }

        $a = new A();
        $b = new A();


        $c = new B(3);
        $d = new B(9);
        $e = new B();

        print_r($c->elementos);
        print_r($d->elementos);
        print_r($e->elementos);
        ?>