Problem regarding use of constructors in PHP

Question

My problem is in using Codeigniter custom library but I think it is not specific to that and more related to use of constructors in PHP. I am trying to create a custom controller library in Codeigniter like this...

class MY_Controller extends Controller {
    var $data = array();

    function MY_Controller() {
        parent::Controller();
        $this->data['err'] = 'no';

        $this->load->helper('utilities');
    }
}

Now I create a codeigniter controller class like this...

class api_controller extends MY_Controller {
    function get_data() {
        $this->data['view'] = "data";
        $this->load->view("data_view", $this->data);
    }
    function get_xml() {
        $this->data['part'] = "xml";
        $this->load->view("data_view", $this->data);
    }
}

I want to ask that if the controller class extending the MY_Controller is instantiated when I access urls like api_controller/get_data and api_controller/get_xml, does the constructor of parent class always get called upon, i.e., MY_Controller() is always called.

Am I correct in inferring the following

get_data() called
-> $data => array ('err' => 'no', 'view' => 'data')

get_xml() called
-> $data => array ('err' => 'no', 'part' => 'xml')

Spudley · Accepted Answer · 2011-02-02 10:22:09Z

4

Your code looks like it's using the PHP4 syntax for constructors. You should switch to the PHP5 syntax.

PHP4:

class MyClassName {
    function MyClassName() {...}  //constructor.
}

PHP5:

class MyClassName {
    function __construct() {...}  //constructor.
}

You can then call the constructor of a parent class by calling parent::__constructor(); from within the child class's __constructor() method:

class MyClassName extends SomeOtherClass {
    function __construct() {
        //...code here runs before the parent constructor.
        parent::__construct();
        //...code here runs after the parent constructor.
    }
}

answered Feb 2, 2011 at 10:22

Spudley

169k39 gold badges240 silver badges309 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Phil Sturgeon Over a year ago

Upgrade to CI 2.0 for proper use of __construct() all the way through or some versions of PHP will not handle the constructors properly. Some versions can have __construct() map to PHP4-style Controller, but CI 2.0 just removes all PHP 4 style constructors.

Sondre · Accepted Answer · 2011-02-02 10:12:45Z

2

For PHP in general the parent constructor is not called default if the child has a constructor. Constructors. It can be called using parent::_construct();

If you're using php 5+ you should go with the new recommended style of using function __construct() instead of the old style with a function named the same as a class.

As for CI-specific stuff I can't help you, sorry!

answered Feb 2, 2011 at 10:12

Sondre

1,89819 silver badges34 bronze badges

Comments

Jake N · Accepted Answer · 2011-02-02 10:16:35Z

2

If you do not override __construct() in MY_Controller then Controller's __construct() will get run.

If you override it and then called parent::__construct() then it will run your own and the parent's.

So if you wanted it to run the parent's and your own you would do this

class MY_Controller extends Controller 
{
    var $data = array();

    function __construct()
    {
        parent::__construct();
        // Your code here
    }
}

answered Feb 2, 2011 at 10:16

Jake N

10.6k12 gold badges69 silver badges114 bronze badges

Comments

Riccardo Galli · Accepted Answer · 2011-02-02 10:12:52Z

0

Yes, the parent constructor it is always called (you may want to rewrite them as __construct() however, thinking also at codeigniter 2.0 ). If you really are in doubt toss in it an echo and see it for yourself.

Also the $this->data part is correct to me

answered Feb 2, 2011 at 10:12

Riccardo Galli

13.1k6 gold badges69 silver badges63 bronze badges

Comments

Carlos Mora · Accepted Answer · 2011-02-02 12:47:05Z

0

You are right in your affirmations about the data array contents. In you code you wrote:

function MY_Controller() {
    parent::Controller();

so the parents's class constructor is being called. There are lots of comments about PHP4 and PHP5 syntax, but basically everithing is ok.

In your question you wrote

that if the controller class extending the MY_Controller is instantiated

that is not correct. The instance is an object of class api_controller, calling the MY_Controller constructor is made using the same object. That is not the same, that is basic for polimorphism.

answered Feb 2, 2011 at 12:47

Carlos Mora

1,1942 gold badges13 silver badges31 bronze badges

Comments

wickedone · Accepted Answer · 2012-04-06 00:04:18Z

0

class Blog extends CI_Controller {

       public function __construct()
       {
            parent::__construct();
            // Your own constructor code
       }
}

edited Apr 6, 2012 at 0:04

wickedone

5401 gold badge6 silver badges18 bronze badges

answered Mar 28, 2012 at 14:22

Prabhakar

1

Collectives™ on Stack Overflow

Problem regarding use of constructors in PHP

6 Answers 6

1 Comment

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

1 Comment

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related