“The most important advantage of an object-oriented programming language is that the objects—for instance, various objects in a video game—can be specified independently and then combined to create new programs. Writing a new object-oriented program sometimes feels a bit like throwing a bunch of animals into a cage and watching what happens. The behavior of the program emerges, as a result of the interactions of the programmed objects. For this reason, as well as the fact that object-oriented languages are relatively new, you might think twice about one for writing a safety-critical system that flies an airplane.”