Inheritance and visibility - PHP

Question

I have difficulties in understanding why we get the output of this code:

<?php

class Bar 
{
    public function test() {
        $this->testPrivate();
        $this->testPublic();
    }

    public function testPublic() {
        echo "Bar::testPublic\n";
    }

    private function testPrivate() {
        echo "Bar::testPrivate\n";
    }
}

class Foo extends Bar 
{
    public function testPublic() {
        echo "Foo::testPublic\n";
    }

    private function testPrivate() {
        echo "Foo::testPrivate\n";
    }
}

$myFoo = new foo();
$myFoo->test(); 
?>

So Foo extends Bar. $myfoo is an obect of the class Foo. Foo doesn't have a method, called test(), so it extends it from its parent Bar. But why the result of test() is

Bar::testPrivate 
Foo::testPublic

Can you please explain me why the first isn't Foo::testPrivate, when this parent's method is overridden in the child?

Thank you very much in advance!

Answer 1

Probably becuase testPrivate is, as the name already suggests, a private method and won't be inherited / overwritten by class inheritance.

On the php.net manual page you probably got that code from it explicitely states that We can redeclare the public and protected method, but not private

So, what exactly happens is the following: The child class will not redeclare the method testPrivate but instead creates it's own version in the "scope" if the child object only. As test() is defined in the parent class, it will access the parents testPrivate.

If you would redeclare the test function in the child class, it should access the childs? testPrivate() method.

Answer 2

Private methods are not visible to anything but the declaring class. Since you call testPrivate from the parent class, the only method it has access to is its own declaration of the method. Thus you get the output you see. Had the access modifier been protected, however, then you would get the output you expect, since protected methods are visible throughout the inheritance chain.