@romainneutron & @stof sure your points are valid... But here, it is either an anonymous function, either a string, [which works in 5.3](http://3v4l.org/YP8Wo).

But as you can't control the form of `$h['handler']`, as it may be an array, described by @stof (and @romainneutron), you should use the `call_user_func`, as ugly as that is.