plac is targetting Python programmers, sys-admins, scientists and in general people writing throw-away scripts for themselves, choosing the command-line interface because it is quick and simple. Such users are interested in a small learning curve: they just want to be able to write a simple command line tool from a simple specification, not to build a command-line parser by hand, as required by the modules in the standard library. plac may also be appealing to more sophisticated users interested in implementing command-oriented domain specific languages to script or test their applications in an automatic way.