ObjectSort.php: Syntax didn't work with PHP7

src/Alecsia/AnnotationBundle/Twig/Extension/ObjectSort.php

@@ -9,7 +9,8 @@ function basic_sort($key, $comparison) {
    return function ($first, $second) use ($key, $comparison) {
       if (is_array($key)) {
          for ($i = 0; $i < count($key); $i++) {
-            $result = $comparison($first->$key[$i](), $second->$key[$i]());
+            $member_function = $key[$i];
+            $result = $comparison($first->$member_function(), $second->$member_function());
             if ($result != 0)
                return $result;
          }