PHP类的私有属性和方法

Question

Noticed something about PHP's classes and I don't know if it's a bug or why it works, this is the code:

<?php
class A {
    private $prop = 'value';

    public function fun()
    {
        $obj = new A;
        $obj->echoProp();
    }

    private function echoProp()
    {
        echo 'Prop has value: '.$this->prop;
    }
}

$obj = new A;
$obj->fun();

And the result isn't an error as I was expecting since I'm calling a private method (tested on PHP 5.3.10-1ubuntu3.7 with Suhosin-Patch). The result is "Prop has value: value"

Answer 1

只要你在课堂上，就可以在任何实例上调用你的类的私有方法。

Answer 2

At the php documentation http://www.php.net/manual/en/language.oop5.visibility.php#language.oop5.visibility-other-objects it says:

Visibility from other objects

Objects of the same type will have access to each others private and protected members even though they are not the same instances. This is because the implementation specific details are already known when inside those objects.

So this isn't a bug but a wanted feature of php.