Thanks, all, for the help! Much appreciated! I don't know if I've ever run across an online community that welcomes newbies as warmly as this one.

It seems that, as always, there's more than one way to do it.

The suggestion about using local typeglobs got me thinking that really what I want to do can be done more cleanly like this: Define the helper subroutine x() once at the outside level. Have a variable that modifies its behavior appropriately, and let that variable be declared as local within each subroutine that's going to call the helper.