Safe Extraction Operator in Chains in OOP in PHP

The safe extraction operator ?-> can be used in call chains. Let's look at an example. Suppose we have the following classes:

php<?php
  class User {
    public $city = null;
  }
  
  class City {
    public function getName() {
      return 'city name';
    }
  }
?>

Suppose we want to get the user's city through the chain:

php<?php
  $user = new User();
  $user->city = new City();
  
  echo $user->city->getName();
?>

In case the city is equal to null, calling such a chain will cause an error:

php<?php
  $user = new User();
  $user->city = null;
  
  echo $user->city->getName(); // error
?>

To suppress the error, we can use the safe extraction operator:

php<?php
  $user = new User();
  $user->city = null;
  
  echo $user->city?->getName();
?>

Suppose now the city can also be null. In this case, we can use the operator safe extraction twice:

php<?php
  $user = null;
  
  echo $user?->city?->getName();
?>

php<?php
  class Employee {
    public $name;
    public $position;
    
    public function __construct($name, $position)
    {
      $this->name = $name;
      $this->position = $position;
    }
  }
  
  class Position {
    private $name;
    
    public function __construct($name)
    {
      $this->name = $name;
    }
    
    public function getName() {
      return $this->name;
    }
  }
  
  $position = new Position('developer');
  $employee = new Employee('john', $position);
  
  echo $employee->position->getName();
?>