Warning. That eval solution needs error checks. Else you could get very confused working out why you are getting no result, when the problem is that $routine expects to be sharing some variables with its environment, the environment doesn't have them, and strict finds this to be a situation worth complaining about.

(Just to list one non-obvious way that a non-trivial error in $routine may need to be handled.)

UPDATE
Re the reply, I understand fully. I just like pointing these things out because you have to expect people to just lift code from here directly without understanding the issues. So if you are posting it as a suggestion, it should look like production code.

That said, I find the eval solution painful on the face of it. I would prefer to solve that with just using Filter::Simple and a few well-chosen macros. If I was going to solve things that way. Which I would probably avoid for reasons listed above...