sub what_i_want : Local {
   $c->detach("login") unless $c->user_exists... roles... etc...
   do_interesting_restricted_stuff()
}

sub login : Local {
    if ( authenticated... )
    {
        my $destination = $c->request->path eq 'login' ?
              $c->uri_for("/") : $c->uri_for( "/" . $c->request->path );
        $c->response->redirect($destination);
        $c->detach();
    }
}