Returns a callable for the given controller.
string $controller A Controller string:
mixed A PHP callable
protected function createController($controller) {
if (false === strpos($controller, '::')) {
throw new \InvalidArgumentException(sprintf('Unable to find controller "%s".', $controller));
}
list($class, $method) = explode('::', $controller, 2);
if (!class_exists($class)) {
throw new \InvalidArgumentException(sprintf('Class "%s" does not exist.', $class));
}
return array(
new $class(),
$method,
);
}