Error with resolution operator while referencing model type depending on dynamic variable (PHP 5.2)

Question

Background Information:

I am trying to simplify the structure of my Yii app, by moving a common function from child classes into the base class they are extending from.

I moved the loadModel($id) function from the User (child) controller into the Base controller.

Before, in UserController.php. This works:

public function loadModel($id) {
    $model = User::model()->findByPk($id);
    if ($model === null)
        throw new CHttpException(404, 'The requested page does not exist.');
    return $model;
}

After, I removed the above function, and placed it into the Controller.php, which is inherited by UserController, and many others:

public function loadModel($id) {
    $type = modelname(); // returns a string, i.e.: "User"
    $model = $type::model()->findByPk($id);
    if ($model === null)
        throw new CHttpException(404, 'The requested page does not exist.');
    return $model;
}

Problem:

I have tried this out on my local PC, running PHP 5.4.4, which works as expected, but when this is uploaded into the testing server running PHP 5.2, this throws a HTTP Error 500 (Internal Server Error). On viewing the error logs, the error was PHP Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM error, which is referring to the resolution operator on the third line.

Question:

• Any reason why the resolution operator fails on PHP 5.2 in this case? and,
• Are there any workarounds to making this work with the same effect?

=================

Additional Information:

The global modelname function I am using, which returns the model name, i.e.: "User":

function modelname() {
    return Yii::app()->controller->id;
}

Answer 1

I have found the answer here:

http://php.net/manual/en/language.oop5.paamayim-nekudotayim.php

The Scope Resolution Operator (also called Paamayim Nekudotayim) or in simpler terms, the double colon, is a token that allows access to static, constant, and overridden properties or methods of a class.

When referencing these items from outside the class definition, use the name of the class.

As of PHP 5.3.0, it's possible to reference the class using a variable. The variable's value can not be a keyword (e.g. self, parent and static).

Basically, I had to upgrade the PHP version to be able to reference a class dynamically.

Answer 2

Actually, you don't have to upgrade to reference the class dynamically. Yii does it without and yii supports PHP 5.2. If you are interested, I can see if I can dig up how it is done, but I've run into the same problem and resolved it on PHP 5.2

Edit: Ok, here's the info. I posted the original info on a Yii wiki page.

Here's the code that returns a Yii singleton model:

    $thisModel = call_user_func($modelname, 'model');

But, per DCoder, it looks like CActiveRecord::model($modelname) will also work:

Yii info here: http://www.yiiframework.com/doc/api/1.1/CActiveRecord#model-detail