schlitt.info - php, photography and private stuff
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- Revision 1
- by Tobias Schlitt
- Wed, 19 Nov 2008
- 23:29:46 +0100
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Reflecting private properties
I recently stumbled over reflecting private properties in PHP again. As you might know, this was not possible until now and if you tried this:
<?php
class Foo
{
private $bar = 23;
}
$obj = new Foo();
$refObj = new ReflectionObject( $obj );
$refProp = $refObj->getProperty( 'bar' );
echo $refProp->getValue( $obj );
?>PHP thanked it to you with this:
ReflectionException: Cannot access non-public member Foo::bar in /home/dotxp/dev/ez/ezcomponents/trunk/reflection.php on line 12While it is absolutly correct that direct access to private properties is strictly forbidden, it is quite disturbing that even reflection cannot do it when you do metaprogramming where accessing private properties can be essential. Today things changed for PHP 5.3 and 6, after Derick and me managed to convince Marcus and Derick provided a patch. You still need to explicitly state that you want to access the value of a protected/private property through reflection by the new method setAccessible() (which is a good thing to avoid people doing stupid things accedentally), but you finally get the access to it:
<?php
class Foo
{
private $bar;
}
$obj = new Foo();
$refObj = new ReflectionObject( $obj );
$refProp = $refObj->getProperty( 'bar' );
// Gather access to this properties value, although it is private
$refProp->setAccessible( true );
echo $refProp->getValue( $obj );
?>This code should not throw an exception to you, but print the desired 23 value.
Thanks to Marcus and Derick for getting this finally done, so that we can soon forget about ugly hacks in the metaprogramming and testing area.
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Comments
-
Derick
It's setAccessible(), not setAccesible().
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Toby
K, fixed here, too. ;)
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Michael Gauthier
Does the new method return a clone of internal objects? If not, encapsulation could be broken. For example, you could return an internal private property and modify it in a way that would break the class.
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sapphirecat
The first code snippet worked in 5.1.6--something was broken since then.
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Derick
No, it does not clone anything. You can't change the value though... just read it.
Link to comment -
Toby
No, objects stored in private properties are not cloned and you are correct, that encapsulation is broken by this. This is the reason for the setAccessible() method, to ensure the developer knows, what he does.
Link to comment -
Fran
It seems that this does not works now:
Link to comment
Fatal error: Call to undefined method ReflectionProperty::setAccessible()
My version:
PHP 5.2.10-2ubuntu6.4 with Suhosin-Patch 0.9.7 (cli) (built: Jan 6 2010 22:41:56)
Someone knows how to do it now? -
Fran
Oops! I see that you're using PHP5.3, so forget my previous comment, it's clear that the problem should be that this feature is not supported on PHP5.2 that's what I'm using.
Link to comment -
Ahmad Al Jayousi
Ahmad Al Jayousi
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E-mail: aaljayousi@philadelphia.edu.jo -
Lu4
I think that using setAccessible(true) is a rubbish, when people are using reflection aren't they already aware of what are they doing?
Link to comment -
Lu4
Reflection is good for delegates implementation, not just call_user_func function that calls public class members but, the real delegates to private class members. Things like Events and EventHandlers can not be implemented without delegates and blocking this feature makes php lack huge class of OOP patterns that are common to other languages. Check
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http://stackoverflow.com/questions/4584182/the-correct-way-of-doing-delegates-or-callbacks-in-php -
Adrian
Hi have, principally, the same approach but more bound to the concern, imho:
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<?php
$reflectedProperty = new \ReflectionProperty('BareClassName', 'desiredPropertyName');
$reflectedProperty->setAccessible(true);
echo $reflectedProperty->getValue($instanciatedClass);
?>
I write this here because it took myself a bit to get the approach of the reflection; the idea is with ->getValue get the value of the reflected property *in context* to the object passed in as parameter. -
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