PHP OOP - Wrong variables returned?

Question

Ok, so, with the code below:

class Core {
    public $child;
    public function start() {
        $child = Loader::instance('Child');
        print_r($this);
    }
}

class Loader extends Core {
    public static $instances;

    public static function instance($class) {
        if(!isset(self::$instances[$class])) {
            self::$instances[$class] = new $class();
        }

        return self::$instances[$class];
    }
}

class Child extends Core {
    public function __construct() {
        parent::__construct();

        $this->child = 'test';
    }
}

Loader::instance('Core')->start();

I should be able after a print_r($this) to see:

Core Object
(
    [child] => test
)

instead of

Core Object
(
    [child] => 
)

what is happening now?

Thanks again..

Tadeck · Accepted Answer · 2011-05-09 00:37:07Z

2

Within the start() method of Core class you use variable $child, that is not the property of the object. Instead write:

class Core {
    public $child;
    public function start() {
        $this->child = Loader::instance('Child')->child;
        print_r($this);
    }
}

and tell me, whether this is what you wanted to accomplish.

EDIT:

I believe you can achieve what you want by referencing static variables. But be careful, how they work. Moreover, you will not see the result by invoking print_r().

Here is the code:

class Core {
    static $child;
    public function start() {

        // invoking code that changes Core::$child inside
        $child = Loader::instance('Child');

        print_r($this);
    }
}

and

class Child extends Core {
    public function __construct() {
        parent::__construct();

        // changing static variable $child of both Core and Child
        self::$child = 'test';
    }
}

edited May 9, 2011 at 0:37

answered May 8, 2011 at 23:54

Tadeck

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7 Comments

Gabriel Santos Over a year ago

codeclass Child extends Core { public function __construct() { parent::__construct(); $this->variable = 'test'; } }

Tadeck Over a year ago

@Gabriel I have updated answer (added ->child). Does it work for you now?

Gabriel Santos Over a year ago

Yes.. now my question is: if I do the follow

class Child extends Core {     public function __construct() {         parent::__construct();          $this->child = 'test';     } }

I can't auto-update Core->child variable with 'test' value?

Tadeck Over a year ago

In that case object of class Child is the instance of Core class. In these terms you are already doing it. But if you are talking about $child being instance of class Child and $core being instance of class Core, then you have to separately change the value of $core->child. It is not done automatically, as object of class Core is not the same as object of class Child. They are only similar in types. This is basic understanding of how classes work.

Tadeck Over a year ago

I have updated the answer - you may be looking for static variables, but you should know how they work. And they won't be displayed when the print_r is invoked.

|

SIFE · Accepted Answer · 2011-05-08 23:51:50Z

0

$child = Loader::instance('Child');

Shoulld be:

$this->child = Loader::instance('Child');

answered May 8, 2011 at 23:51

SIFE

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Comments

mario · Accepted Answer · 2011-05-08 23:51:52Z

0

This is where your print_r output comes from:

    $child = Loader::instance('Child');
    print_r($this);

And it will print the current object ($this is a Core), rather than the newly instantiated $child (which would be a Child class).

answered May 8, 2011 at 23:51

mario

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