Why can you call a private method on a new instance made inside a method of the same class type, in PHP?

Question

Why can you call a private method on a new instance made inside a public method of the same class type?

class Foo
{
    private function thePrivateMethod()
    {
        echo 'can not be called publicly?';
    }

    public function thePublicMethod()
    {
        $clone = new Foo;
        $clone->thePrivateMethod();
    }
}

$foo = new Foo();
$foo->thePublicMethod();
$foo->thePrivateMethod();

The above results in the following output when run in PHP 7.3.18

can not be called publicly?

Fatal error:  Uncaught Error: Call to private method Foo::thePrivateMethod() from context

Intuitively, I would expect the first call to Foo::thePrivateMethod() to also cause a fatal error. But I'm not able to find in the documentation that this behaviour would be allowed?

Answer 1

Basically, following the Object Oriented paradigm you can always call a private or protected method within the own class. Here is a table that can explain better the concept behind 'Why does this work?'

The first time, you call a public method that recall a private method within the context of the class, so it's allowed. The second time, you call directly a private method, that is not allowed outside the class.

Is the same concept of the attributes, if you declare aprivate $test within the class, you cannot access to it by $foo = new Foo();$foo -> test;

but instead, you need to declare a public method that do this for you, and then call it to get the value of $test : $foo -> getTest();

NB. since you have init the object within the context of the class, it's always allowed.