note 100379 rejected from language.oop5.visibility by frozenfire
| From: | frozenfire@php.net | Date: | Fri, 15 Jul 2011 02:20:01 +0000 |
| Subject: | note 100379 rejected from language.oop5.visibility by frozenfire | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-181542@lists.php.net to get a copy of this message | ||
Note Submitter: ryan dot m dot lange at gmail dot com
----
Here's a bizarre little quirk that I haven't seen mentioned before:
<?php
class ParentClass
{
private $foo;
public function __construct()
{
$this->foo = 'foo';
}
public function foo()
{
echo $this->foo;
}
}
class ChildClass1 extends ParentClass
{
public function bar()
{
echo $this->foo;
}
}
class ChildClass2 extends ParentClass
{
public function __construct()
{
$this->foo = 'bar';
}
public function bar()
{
echo $this->foo;
}
}
$parent = new ParentClass();
$parent->foo(); // "foo"
$child1 = new ChildClass1();
$child1->foo(); // "foo"
$child1->bar(); // "Notice: Undefined property: ChildClass1::$foo in [file] on line
[line]"
$child2 = new ChildClass2();
$child2->foo(); // <nothing>
$child2->bar(); // "bar"
?>
The output of ChildClass1::foo() and ChildClass1::bar() are expected given the private visibility of
$foo. However, the output of ChildClass2::foo() and ChildClass2::bar() are completely unexpected
according to the documentation (to my understanding, at least).
Setting a private property of a parent class in the constructor of a child class is not only
possible, but essentially "hijacks" that property away from the parent class.