The right way to set a protected variable from another class PHP

Question

I have this issue to solve: I create two classes where the second is an extends of the first and there I want to set and get an variable from the first class, but... I can't find the 'right' way to do it basically this:

class class_one {

    protected $value;
    private $obj_two;

    public function __construct() {
        $this->obj_two = new class_two;
    }

    public function firstFunction() {

        $this->obj_two->obj_two_function();

        echo $this->value; // returns 'New Value' like set in the class two

    }

}

class class_two extends one {   
    public function obj_two_function() {    
        "class_one"->value = 'New Value';   
    } 
}

How can I do this?

Answer 1

First class should not initialize the second, unless you're seeking Uroboros! Protected variables can be set by an extended class without any function support. Just go $this->protVariable = "stuff";

But you will need a function that may be protected to set ClassOne's private variable from the second class. Likewise a function must be made in ClassOne to actually retrieve its value.

class ClassOne {
    private $privVariable;
    protected $protVariable;

    /**
     */
    function __construct () {

    }

    /**
     * This function is called so that we may set the variable from an extended
     * class
     */
    protected function setPrivVariable ($privVariable) {

        $this->privVariable = $privVariable;

    }

}

In the second class you can then call to parent::setPrivVariable() to set the value using the parent function.

class ClassTwo extends \ClassOne {

    /**
     */
    public function __construct () {

        parent::__construct ();

    }

    /**
     * Set the protected variable
     */
    function setProtVariable () {

        $this->protVariable = "stuff";

    }

    /**
     * see ClassOne::setPrivVariable()
     */
    public function setPrivVariable ($privVariable) {

        parent::setPrivVariable ( $privVariable );

    }

}