用于访问子类的子类

Question

I have a single class that calls aload of other classes;

require_once('class.database.php');
require_once('class.users.php');

Class Bootstrap {

     public $db;
     public $users;

     public function __construct() { $this->db = new Database(); $this->users = new Users(); }
}

$est = new Bootstrap();

And that class works fine, but lets say in my Database class I have;

 class Database {
     public function __construct() { }

     public function foo() {
         echo 'hi';
     }
 }

And then from the users class, I'd like to reference the function, but I wanna keep the code clean and therefore want to steer away from statics.

I've tried referencing it such as:

 * $est->db->foo();
 * $db->foo();

But none of them work, could somebody please show me the correct way to call it. Thanks!

Answer 1

Currently you have given yourself no way to access the specific db instance inside Bootstrap from within the Users class.

You could:

1. Hand the db instance to Users when you instantiate:

   $this->users = new Users($this->db);

2. Hand the Users class a reference to Bootstrap when you instantiate:

   $this->users = new Users($this);

3. Have the users class setup its own database connection:

   class Users { public function __construct() { $this->db = new Database(); } }

4. Setup statics