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Request #65718 __inClone() magic method to alter an object's inclusion in clones
Submitted: 2013-09-20 03:50 UTC Modified: 2013-09-20 04:10 UTC
From: metamarkers at gmail dot com Assigned:
Status: Wont fix Package: Class/Object related
PHP Version: Irrelevant OS:
Private report: No CVE-ID: None
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From: metamarkers at gmail dot com
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 [2013-09-20 03:50 UTC] metamarkers at gmail dot com 
Description:
------------
It would be nice if an object could determine whether or not it should be 
included in a clone, by returning a value that should be used in its stead, or an 
updated clone of itself, or anything of the like.

Test script:
---------------
class Foo { }

class Bar {
    public function __inClone ( $clone ) {
        return $clone instanceof Foo ? null : $this;
    } 
}

$foo = new Foo();
$foo->bar = new Bar();
$foo2 = clone $foo;
isset($foo2->bar); // false

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 [2013-09-20 04:10 UTC] requinix@php.net
-Status: Open +Status: Wont fix
 [2013-09-20 04:10 UTC] requinix@php.net 
That decision should be up to Foo, not up to Bar. If Foo is unaware that it no 
longer has a $bar member then that could introduce all sorts of unexpected and 
difficult to trace bugs.
Besides, PHP does not do deep copies during cloning anyways.

Implement Foo::__clone() such that it would normally clone all its members. Then 
you can
(a) Make it not clone its $bar and instead unset() it
(b) Implement a private Bar::__clone() so attempting to clone $bar raises a fatal 
"Call to private Bar::__clone from context 'Foo'"
(c) Implement a public Bar::__clone() and throw an Exception so attempting to 
clone $bar fails
Whichever way, Foo is responsible for knowing that Bar cannot be cloned and should 
adjust its own behavior accordingly.
 [2013-09-20 04:30 UTC] metamarkers at gmail dot com 
Valid points. Thanks for reading.
 
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