title: Apply Rails controller filter to all controllers of a particular namespace?
body: <p>I have a bunch of controllers in a namespace <code>Foo</code>.
  I'd like to apply a <code>before_filter 'require_user'</code> to all of them, but not to other controllers, that do not belong to <code>Foo</code> namespace.</p>
  
  <p>Is there any way to accomplish this besides explicitly invoking a before_filter method in each controller?</p>