title: Qt signals and slots - are they intended for GUI only or for entire app architecture?
body: <p>I'm very curious - are Qt's signals and slots (delegate pattern?) intended only for GUI callbacks, or they are perfectly fine and <strong>intended</strong> for entire apps? I mean, is it better to split apps into small, self-contained objects (classes) and interconnect them via signals and slots? And if so, what is the recommended way to return a value from a signal (request-like signal that is used to return something), since Qt's signals' return values are ignored?</p>