Put them in a helper and include them in your controller(s).
If you want them to be available *everywhere*, write a new helper, say GlobalHelper in a file called global_helper and in your application_helper and application_controller say
class Application[Helper|Controller] include GlobalHelper ... end
BTW, a better way to implement this function is:
def empty_string? s !(s && !s.empty?) end
Better still, you can add an empty? method to NilClass, which negates the need for the function in the first place:
class NilClass def empty? true end end
This means that you can now call empty? on a nil object or a string, nil always returning true.
If you have many functions like that, you should really spend some time reading the pickaxe book and the Ruby api docs. Also have a look at the ruby facets library. I think you'll find that a lot of what you are trying to do is either already there or can be implemented in a better way.
Max
