A very long note on error-reporting

C++ has a love-hate relationship with error-reporting. By "error-reporting" in this context, I mean "what to do, when you can't do what you were asked". The classical, typical, and still the best-practice way to report this kind of "disappointment" in C++ is to throw an exception. We have seen in the previous chapters that, sometimes, throwing an exception is the only sensible thing to do, because there is no way to return to your caller. For example, if your task was to construct an object, and construction fails, you cannot return; when a constructor fails, the only same course of action is to throw. However, we have also seen (in Chapter 9, Iostreams) that C++'s own <iostream> library does not take this sane course of action! If the construction of a std::fstream object fails (because the named...