A complete treatment of programming principles and software design is clearly beyond the scope of this book. However, this chapter includes some core principles that we have found to be central to good software engineering.

Engineering

Do Not be Afraid to Do Engineering

The ultimate goal of professional software development is to create something useful—an engineering task much more than a scientific one. (Science is more immediately concerned with understanding the world around us, which is admittedly necessary, but not sufficient, for engineering.)

Resist the temptation to write code to model scientific realities that include all theoretical possibilities. It is not a “hack” to write code that has practical limitations if you are confident those limits do not affect the utility of the resulting system.

For example, imagine you need a data structure for tree traversal and choose to write a stack. The stack needs to hold at least as many items as the maximum depth of any tree. Now suppose that there is no theoretical limit to how deep one of these trees can be. You might be tempted to create a stack that can grow to an arbitrary size by reallocating memory and copying its items as needed. On the other hand, your team's understanding of the application may be such that in your wildest imagination you'd be amazed to see a tree with depth greater than 10. If so, the better choice would be to create a fixed-length stack with a maximum of, say, 50 elements.