def uptodate_if_isdir(path):
    def do_check():
        return os.path.isdir(path)
    return do_check

def uptodate_if_older_than(dependency, *targets):
    def do_check():
        dep_mtime = os.stat(dependency).st_mtime
        mtimes = [os.stat(t).st_mtime for t in targets if os.path.isfile(t)]
        target_mtime = max(mtimes) if mtimes else 0
        return dep_mtime < target_mtime
    return do_check