Property Name from Another Object in OOP in PHP

A property name can even be a property of another object. Let's say we have the following class User:

php<?php
  class User
  {
    public $name;
    public $surn;
    
    public function __construct($name, $surn)
    {
      $this->name = $name;
      $this->surn = $surn;
    }
  }
?>

Let's create an object of this class:

php<?php
  $user = new User('john', 'smit');
?>

Let's also say we have a class Prop, which will store the name of a property in its value property:

php<?php
  class Prop
  {
    public $value;
    
    public function __construct($value)
    {
      $this->value = $value;
    }
  }
?>

Let's create an object of this class:

php<?php
  $prop = new Prop('name'); 
?>

Now, using this object, let's output the user's name:

php<?php
  echo $user->{$prop->value}; // outputs 'john'
?>

php<?php
  class Employee
  {
    public $name;
    public $salary;
    public $position;
    
    public function __construct($name, $salary, $position)
    {
      $this->name = $name;
      $this->salary = $salary;
      $this->position = $position;
    }
  }
?>

php<?php
  class Data
  {
    public $prop1 = 'name';
    public $prop2 = 'salary';
    public $prop3 = 'position';
  }
?>