Is there any reason you need the subroutine to be separate for each element? Let perl compile it once and use the same coderef for each element if you can, as that saves on memory and work. That doesn't prevent you from overriding those definitions with another coderef if you need to.

Also, don't be confused by the "DUMMY" bit (not that you've given any indication that you are confused -- mainly this is for the benefit of others). Data::Dumper can't deal with coderefs, so it just inserts a subroutine that is effectively a no-op, and returning "DUMMY" is as good as anything else.