Clone object with sub-objects in PHP

Question

I have an object (called a) which contains an array of two other objects (called b). I am trying to clone that object (a). When i clone the object, i also want to clone the other two objects. However, when i run a code to change the sub-objects(b) in the original object(a) array, it also changes the array with objects(b) in the cloned object(a). How do i prevent this? This is my code:

<?php
class a{
    public $b = array();

    function __clone(){
        foreach($this->b AS $key => $b){
            $this->b[$key]  = clone $b;
        }   
    }

    function addB($name,$b){
        $b->setA($this);
        $this->b[$name] = $b;
    }


}

class b{
    public $a;
    public $var = 'no';
    function execute(){
        $this->var  = 'yes';
    }

    function seeB1(){
        return $this->a->b['b1']->var;
    }

    function setA($a){
        $this->a    = $a;
    }
}



$a1 = new a;
$b1 = new b;
$b2 = new b;

$a1->addB('b1',$b1);
$a1->addB('b2',$b2);


//Clones A
$a2 = clone $a1;


$a1->b['b1']->execute();

var_dump($a1->b['b2']->seeB1()); //This should say Yes. It does
var_dump($a2->b['b2']->seeB1()); //This should say No. It says Yes

?>

The output is:

string 'yes' (length=3)

string 'yes' (length=3)

What i want to do with this script is clone A. After i clone A, i run the function execute() of the original b1 to change $var. Then I view original b1 from the original b2. This shows that $var of original b1 has changed, as it should be. However, if I view cloned b1 from cloned b1, it also shows that $var has changed. It shouldnt.

What am i doing wrong?

Regards, Tom.

montexristos · Accepted Answer · 2014-09-25 12:39:52Z

2

You can try to replace your __clone function with the following:

function __clone() {
    foreach ($this as $key => $value) {
        if (is_object($value) || (is_array($value))) {
            $this->{$key} = unserialize(serialize($value));
        }
    }
}

By using the serialize/unserialize method you will definitely avoid changing the original properties of the object.

Tested it and it works fine for simple objects like the ones in your example.

answered Sep 25, 2014 at 12:39

montexristos

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