子类访问父的私有方法？

Question

A user posted a comment on PHP Visibility manual page . It's the second most voted comment. He used this code example:

<?php
abstract class base {
    public function inherited() {
        $this->overridden();
    }
    private function overridden() {
        echo 'base';
    }
}

class child extends base {
    private function overridden() {
        echo 'child';
    }
}

$test = new child();
$test->inherited();
?>

Output will be "base".

As I understand it: the "child" class inherits the inherited() method. Does not inherit the overridden() method since it is private but defines its own one instead. But when the test object (instance of child class) runs the inherited() method it outputs "base".

So my questions are:

1. How come the child runs a method to which it does not have access?
2. Why it does not run its own redefined method?

Answer 1

Since in the child class you didn't define any function inherited() , it'll have to call its parent's method. As the comment you referenced says:

... private methods are visible only for the class that defines them and the child class does not see the parent's private methods. ...

That said, since you don't have any public method to reference the child's private method, such as:

class child extends base {
    public function inherited() {
        $this->overriden();
    }

    // ...

From my point of view, calling $test->inherited() would use the scope of its parent, so, what happens if you create an instance of the parent class and call $this->inherited() . It'd output base .

Try doing what i said above: in the child class, copy and paste the parent's inherited method. It will output child .

I'm not sure this is well explained, if it is, maybe it can help you understand a bit more, if it's not, someone may help me improve it.