PHP - Class Advice

I have mysqli object in Database class base:

[color=]database class:[/color]

class Database {
  private $dbLink = null;
  
  public function __construct() {
    if (is_null($this->dbLink)) {
      // load db information  to connect
      $init_array = parse_ini_file("../init.ini.inc", true);
      $this->dbLink = new mysqli($init_array['database']['host'],
                           $init_array['database']['usr'],
                           $init_array['database']['pwd'],
                           $init_array['database']['db']);
  
      if (mysqli_connect_errno()) {
        $this->dbLink = null;
      }
    }
  }

  public function __destruct() {
    $this->dbLink->close();
  }
}


Class derived is Articles where I use object dBLink in base (or parent) class and I can't access to mysqli methods (dbLink member of base class):

Articles class:

require_once ('./includes/db.inc');

class Articles extends Database{
  private $id,
              ....
              ....
             $visible = null;
  
  public function __construct() {
    // Set date as 2009-07-08 07:35:00
    $this->lastUpdDate = date('Y-m-d H:i:s');
    $this->creationDate = date('Y-m-d H:i:s');
  }
  
  // Setter
  ....
  ....

  // Getter
  ....
  ....

  public function getArticlesByPosition($numArticles) {
    if ($result = $this->dbLink->query('SELECT * FROM articles ORDER BY position LIMIT '.$numArticles)) {
      $i = 0;
      while ($ret = $result->fetch_array(MYSQLI_ASSOC)) {
        $arts[$i] = $ret;
      }
      $result->close();
      return $arts;
    }
  }
}


In my front page php I use article class:


include_once('./includes/articles.inc');
$articlesObj = new articles();
$articles = $articlesObj->getArticlesByPosition(1);
var_dump($articles);


[color=]Error that go out is follow[/color]

Notice: Undefined property: Articles::$dbLink in articles.inc  on line 89

Fatal error: Call to a member function query() on a non-object in articles.inc on line 89

If I remove constructor on derived class Articles result don't change 
Please help me

I have an existing instance of my class Database, now I want to call that instance in my Session class, how would I go about doing this?

Hi

Can you call Class A's methods or properties from Class B's methods?

Thanks.

Ok. I know you can pass the object of a class as an argument. Example:


class A {
    function test() {
        echo "This is TEST from class A";
    }
}


class B {
    function __construct( $obj ) {
        $this->a = $obj;
    }

    function test() {
       $this->a->test();
    }

}


Then you could do:

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


Ok so that's one way i know of.

I also thought that you could make a method static, and do this: (assuming class A's test is 'static')

class B {
    function test() {
       A::test(); 
   }
}


But that is not working.


I'd like to know all possible ways of accomplishing this. Any hints are appreciated. thanks

If a class has a constructor but also has a static method, if I call the static method does the constructor run so that I can use an output from the constructor in my static method?

--Kenoli