irule development - fixed variables within iRule context

Hi Boneyard - we have 2 production sites and a single test site. Within the test site (on a single test F5) we run 4 test streams called fn1-fn4. Having a consistent naming standard for LTM units and for virtual servers has been very useful. I use CLIENT_ACCEPTED to set variables. I use switch statements to determine environments, which means that, technically, it's not the most efficient method, however like you, I want a single piece of code to move between environments, and I see the sacrifice of a few CPU cycles as worth it. Obviously an alternative would be to have a separate CLIENT_ACCEPTED iRule per environment....;-

when CLIENT_ACCEPTED {
     Switch on the device name - this tells us whether we are in test or prod
    switch -glob [info hostname] {
    "xxx*" -
    "yyy*" {
         This is a prod site
        set debug 0
        set dg_name "dg_ip_classification"
    }
    default {
         We're in test - determine testing stream
        switch -glob [virtual] {
            "*fn1" {
                set debug 0
                set dg_name "dg_ip_classification_fn1"
            }
            "*fn2" {
                set debug 0
                set dg_name "dg_ip_classification_fn2"
            }
            "*fn3" {
                set debug 0
                set dg_name "dg_ip_classification_fn3"
            }
            "*fn4" {
                set debug 0
                set dg_name "dg_ip_classification_fn4"
            }
        }
    }
    }
}