Accessing Protected Parent Class Variables in PHP: Why Use `$this->bb` Over `parent::bb`?

bb` Over `parent::bb`?" />

Accessing Parent Class Variables in PHP

The provided code demonstrates an issue where a child class is unable to access the protected variable $bb inherited from its parent class. To resolve this, the variable can be accessed using the syntax $this->bb.

<code class="php">class A {
    private $aa;
    protected $bb = 'parent bb';

    function __construct($arg) {
       //do something..
    }

    private function parentmethod($arg2) {
       //do something..
    }
}

class B extends A {
    function __construct($arg) {
        parent::__construct($arg);
    }
    function childfunction() {
        echo $this->bb; // Outputs 'parent bb'
    }
}

$test = new B($some);
$test->childfunction();</code>

Using $this->bb implies that the inherited variable is now part of the current object and can be accessed like any other instance variable.

Additional Note:

While using $this->bb solves the immediate issue, it's important to understand the difference between $this-> and parent:: when accessing inherited variables and methods.

$this-> refers to the current object, while parent:: refers to the parent class. $this-> can be used to access inherited variables directly, while parent:: is used to call parent class methods or access parent class static variables.

For example, if you wanted to override a parent class method while still accessing the original method from the parent class, you could use the following syntax:

<code class="php">class Child extends Parent {
    function myMethod() {
        parent::myMethod(); // Calls the parent class's myMethod()
    }
}</code>

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