How to generate sources before compilation
Sometimes you need to generate sources files before the compilation task runs.
Here is an example that checks for changes in *.yk files and will trigger code generation and recompilation if they change.
Note: on Buildr 1.4.6 and earlier, you may need to add .to_s for things to work properly,
(tracked by https://issues.apache.org/jira/browse/BUILDR-609)