<?php
class Foo {
  private $prop;
  function __construct($prop) {
    $this->prop = $prop;
  }
  public function getPrinter() {
    return static function() { echo ucfirst($this->prop); };
  }
}

$a = new Foo('bar');;
$func = $a->getPrinter();
$func(); // Fatal error: Using $this when not in object context