PHP子类访问父类中的对象

Question

class bm_main {

    public $db;

    public function __construct(){

        $this->db = new db();
    }

}

class bm extends bm_main{

    public function __construct($id){
        $this->db = parent::$db;
            $this->db->save($id);
    }
}

How to access the $db object from parent class so i can use it in the child one

Answer 1

Call the parent constructor so the db class is instantiated:

    public function __construct($id) {
        parent::__construct();
        $this->db->save($id);
    }

The $db property is inherited by the subclass, and is public, so you can access it using $this->db.