There must be an easy way to do this. I build a Flex app using ant that depends on a SWC library, which works fine except that it rebuilds the library whether it needs to or not. How do I tell ant to only run the task if any of the sources files of the library (*.as, *.mxml) are newer than the SWC? I've looked at <dependset but it only seems to delete files, not determine whether a task should be run or not. <depend seems to expect a one-to-one relationship between the source and target files rather than a one-to-many relationship -- I have many input files and one output file, but no intermediate object files. Thanks a lot, Alex