4.3.4 Phony Targets

Rscons supports phony build targets. Normally, a builder produces an output file, and executes whenever the input files or command have changed. A phony build target can be used to register a builder that does not produce an output file. A custom builder can take some action when the input files change even if it does not produce an output file. Such a builder could perform verification or run a test on its source files, possibly failing if some conditions are not met. It could also simply output something to the console, such as an analysis of the source file, whenever it changes. A phony target is signified by passing a Symbol instead of a String as the first parameter (target) to a builder method.