note 78363 deleted from language.oop5.cloning by nlopess
| From: | nlopess@php.net | Date: | Mon, 08 Oct 2007 19:40:57 +0000 |
| Subject: | note 78363 deleted from language.oop5.cloning by nlopess | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-131240@lists.php.net to get a copy of this message | ||
Note Submitter: muratyaman at gmail dot com
----
I think this is a bit awkward:
<?php
class A{
public $aaa;
}
class B{
public $a;
public $bbb;
function __clone(){
$this->a = clone $this->a;//clone MANUALLY!!!
}
}
$b1 = new B();
$b1->a = new A();
$b1->a->aaa = 111;
$b1->bbb = 1;
$b2 = clone $b1;
$b2->a->aaa = 222;//BEWARE!!
$b2->bbb = 2;//no problem on basic types
var_dump($b1); echo '<br />';
var_dump($b2);
/*
OUTPUT BEFORE implementing the function __clone()
object(B)#2 (3) { ["a"]=> object(A)#3 (1) { ["aaa"]=> int(222) }
["bbb"]=> int(1) }
object(B)#4 (3) { ["a"]=> object(A)#3 (1) { ["aaa"]=> int(222) }
["bbb"]=> int(2) }
OUTPUT AFTER implementing the function __clone()
object(B)#1 (3) { ["a"]=> object(A)#2 (1) { ["aaa"]=> int(111) }
["bbb"]=> int(1) }
object(B)#3 (3) { ["a"]=> object(A)#4 (1) { ["aaa"]=> int(222) }
["bbb"]=> int(2) }
*/
?>
Whenever we use another class inside, we must clone it manually. If you have 10s of classes related,
this is rather tedious. I don't want to even think about classes dynamically populated with
other objects. Be careful when designing your classes! You should look after your objects all the
time! This major change on PHP5 vs PHP4 regarding "references" definitely has very good
performance improvements but comes with very dangerous side effects as well..