PHP 类的私有(private)属性和方法

Question

注意到一些关于 PHP 类的东西，我不知道它是否是一个错误或者它为什么起作用，这是代码:

<?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();

结果不是我预期的错误，因为我正在调用私有(private)方法(在 PHP 5.3.10-1ubuntu3.7 上使用 Suhosin-Patch 测试)。结果是“Prop has value: value”

Answer 1

在 php 文档中 http://www.php.net/manual/en/language.oop5.visibility.php#language.oop5.visibility-other-objects它说:

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.

所以这不是错误，而是 php 需要的功能。