[mapserver-users] syntax for passing a perl variable to setexpression

[regina.ctr.niner at faa.gov]

I'm using a perl script to map dynamic
flight tracks against a map of the world.

Would any of you know the correct syntax for using
a perl variable to call setexpression() ?
(I need to build layers based on a variable retrieved from
the database, and have been unsuccessful at using a variable
to set the expression for the applicable class - though
I have gotten a literal to work.)

Any hints would be appreciated.
Thanks!