<?php declare ( strict_types = 1 ) ; namespace foo ; class bar { const x = 'abc' ; /** @var int */ private $y = 1 ; public function __construct ( ) { // do something } public function getY ( ) : int { return $this -> y ; } public function getSomeX ( ) : string { return self :: x ; } public function some ( bar $b ) : string { return $b -> getSomeX ( ) . '-def' ; } }