Bam is a fast and flexible build system. Bam uses Lua to describe the build process. It's takes its inspiration for the script files from scons. While scons focuses on being 100% correct when building, bam makes a few sacrifices to acquire fast full and incremental build times.
Make it optional if an output should be touched or not. If not, bam should check and ensure that the output timestamp has been updated by the tool.