[galaxy-dev] XML wrapper : use cheetath variable in from_work_dir tag

Hello, I don't know how to use a cheetah variable (#set var) inside a XML tag. I mean when I try to do this : #set foo = "file.txt" ... <outputs> <data format="txt" from_work_dir="something/${foo}" name="test"/> </outputs> from_work_dir tag contains "something/${foo}" instead of "something/file.txt" Is there a way to do this ? Regards Laure