oops question

[veeru]

Hi there friends
am kind of new to oops, and i have a question.

Lest say i have a class a, class b extends a, class c extends b..
how can i have access to a property in class a in class b?i tried defining it as public, but it did'nt work for me, any suggestions?

Thanks
Vru

[cranial-bore]

Because b extends a it can access a's properties though they were it's own.
i.e

class B
{
   public function someMethod() {
      return $this->propert_defined_in_a;
   }
} 

Be aware that instantiating class B will not automatically run the constructor for class A, so any properties it defines won't be present.
You can have your class B constructor call the parent constructor if necessary.
If class B has no constructor defined then the class A constructor will run automatically.

class B
{
   public function __construct() {
     parent::__construct();
   }
} 

[veeru]

Okay, looks like i got the picture, but what do i need to do if i need class c to be able to acess properties of class?

[cranial-bore]

It's best not to inherit too deeply because it can get confusing. A better idea is probably to compose or aggregate a new class within the class that needs to use it.

E.g passing one object to another (data access example)
The constructor of the "articles" class receives a reference to the dataAccess object as an argument to the constructor

class articles
{
   private $dataAccess; //object
   public function __construct($dataAccess) {
      $this->dataAccess = $dataAccess;
   }

  public function get_recent($limit = 5) {
    $query = "SELECT title FROM `articles` ORDER BY date DESC LIMIT " . (int) $limit;
    return $this->dataAccess->get($query);
  }
}

//Calling Code
require('dataAccess.php');
$data = new dataAccess();

$articles = new articles($data);
print_r($articles->get_recent(6)); 

Another method is for one class to compose another class it needs

class users
{

  private $dataAccess;

  public function __construct() {
     require_once('dataAccess.php');
     $this->dataAccess = new dataAccess();
   }

   public function create_user($username, $password) {
      $query = "INSERT INTO `users` (username, password) VALUES ($username, $password");
     return $this->dataAccess->insert($query));
   }
} 

[veeru]

Exactly what i was looking for, i have a data access variable in class a and i want it to be available across class b and class c as well, the given example sounds like it could solve my problem.

Thanks