Unfortunately, the value of deep classes is not widely appreciated today. The conventional wisdom in programming is that classes should be small, not deep. Students are often taught that the most important thing in class design is to break up larger classes into smaller ones. The same advice is often given about methods: “Any method longer than N lines should be divided into multiple methods” (N can be as low as 10). This approach results in large numbers of shallow classes and methods, which add to overall system complexity.
