Burada denetleyici fonksiyon kayıt bulunuyor ()

public function register()
{
    	$userdata = array();
    	$formdata = array(
    		'uname' => '',
    		'password' => '',
    		'email' => '',
    		'fname' => '',
    		'lname' => ''
    	);

    	// copy the form as errors
    	$errors = $formdata;

    	// process data if form is submitted
    	if (isset($_POST['submitted']))
    	{
    		// initialize validation library
    		$post = new Validation($_POST);

    		// add filters
    		$post->pre_filter('trim', 'uname', 'fname', 'lname');

    		// set validation rules
    		$post->add_rules('uname', 'required', 'alpha_numeric');
    		$post->add_rules('password', 'required', 'length[6, 12]');
    		$post->add_rules('email', 'required', 'email');
    		$post->add_rules('fname', 'required', 'alpha');
    		$post->add_rules('lname', 'required', 'alpha');
    		$post->add_callbacks('uname', array($this, ' _username_exists'));

    		if($post->validate())
    		{
    			$userdata = array(
    				'username' => $_POST['uname'],
    				'email' => $_POST['email'],
    				'password' => $_POST['password'],
    				'firstname' => $_POST['fname'],
    				'lastname' => $_POST['lname']
    			);

    			$this->user->register($userdata);
    			// url::redirect('test/register_success');
    		}
    		// show form with validation errors
    		else
    		{
    			// repopulate form fields
    			$formdata = arr::overwrite($formdata, $post->as_array());

    			// populate the error fields
    			$errors = arr::overwrite($errors, $post->errors('register_error_messages'));
    		}
    	}

    	// show form
    	$view = new View('register');
    	$view->form = $formdata;
    	$view->errors = $errors;
    	$view->render(true);
    }

Burada geri çağırma işlevi bulunuyor

public function _username_exists(Validation $post)
    {
    	// if add_rules validation found any errors, exit
    	if (array_key_exists('uname', $post->errors())) return;

    	$result = $this->user->check_username_exists($username);
    	if (!$result)
    	{
    		//add error to validation object
    		$post->add_error('uname', 'username_exists');
    	}
    }

Ben geri Funcion için çağrı açıklama eğer mükemmel çalışıyor