Of course, careful coding and use of preprocessor macros is required with C, and we could certainly get away with the same thing in C++ if it weren’t for one problem: a macro has no concept of the scoping required with member functions. The preprocessor simply performs text substitution, so you cannot say something like

or anything even close. In addition, there would be no indication of which object you were referring to. There is simply no way to express class scope in a macro. Without some alternative to preprocessor macros, programmers will be tempted to make some data members public for the sake of efficiency, thus exposing the underlying implementation and preventing changes in that implementation, as well as eliminating the guarding that private provides.