private modifier in php doesn' work like expected-CodePudding

i have this class

class Product {
    public $name;
    private $price2;
    protected $number;

function getNmae() {
    return $this->name;
}

function getPrice() {
    return $this->price2;
}

function getNumber() {
    return $this->number;
}
}

and here I can use private price without any problem?

<?php
include 'oop_test.php';

class Banana extends Product {
   
   
}


$ba = new Banana();
echo $ba->price2 = 2000;

?>

the result like this:

I cannot understand how could I assign value to private variable ?

CodePudding user response：

Looks like you've created a property on-the-fly in this case. A reduced sample shows this:

<?php
class Product {
    private $price2;

    function getPrice() {
        return $this->price2;
    }
}

class Banana extends Product {}


$ba = new Banana();
$ba->price2 = 2000;

echo 'On the fly property: ' . $ba->price2;
echo 'Private property: ' . $ba->getPrice();

That code prints 2000 for the property price2, but nothing is returned from getPrice - so you haven't really written the property price2 on the Product class, but created a new one within the Banana class.

The "original" property from the Product class is not involved here, as it is a private property and thus not available in the Banana class after all.

CodePudding user response：

Actually the display of 2000 does not mean that the parent class value is set.

Your statement only creates a new variable for the class itself, not for the parent class because the price2 is not declared as protected / public.

For private variable... the private scope when you want your property/method to be visible in its own class only.

Try create a method (say setPrice) to set the price2 in the parent class if you need it

<?php
class Product {
    public $name;
    private $price2;
    protected $number;

function getNmae() {
    return $this->name;
}

function setPrice($a) {
   $this->price2 = $a;

}


function getPrice() {
   return $this->price2;

}

function getNumber() {
    return $this->number;
}
}

?><?php
// include 'oop_test.php';

class Banana extends Product {
   
   
}


$ba = new Banana();
//$ba->price2 = 2000;
$ba->setPrice(2001);

echo $ba->getPrice();


?>