Virtual Property

A virtual property is a class property, whose property hooks don’t use the value. The virtual property has no need for actual storage, and rely on other means to provide (get and set) the value.

<?php

class counter() {
     private $count = 1;

     // $next is a virtual property : it doesn't rely on $this->next;
     public $next {
             get => $this->count + 1;
             set {}
     }
}

?>

Documentation

See also https://geekytomato.com/php-8-4-property-hooks-virtual-properties-and-potential-issues/

Added in PHP 8.4+