multiple callbacks with form_validation?

[eluser]Unknown[/eluser]
Is there any way to make this work?

Code:

$this->form_validation->set_rules('foo', 'bar', 'trim|required|callback__foo_check|callback__bar_check');

Right now I've implemented it by combining _foo_check() and _bar_check() as one function, but it's a pain and creates more lines of code than feels necessary.