App Inventor 2, 2nd Edition

Chapter 15. Engineering and Debugging an App

Figure 15-0.

HelloPurr, MoleMash, and the other apps covered in this book’s early chapters are relatively small software projects and don’t really require a significant amount of software engineering. As soon as you take on a more complicated project, you’ll realize that the difficulty of building software increases rapidly for each bit of complexity you add—it is not anywhere close to a linear relationship. You’ll quickly learn that to build even moderately complex software, you need forethought, planning, blueprints, user and system testing, and in general, techniques and skills that are more engineering than programming. For most of us, it takes a few hard knocks before we realize this fact. At that point, you’ll be ready to learn some software engineering principles and debugging techniques. If you’re already at that point, or if you’re one of those few people who want to learn a few techniques in the hope of avoiding some of those growing pains, this chapter is for you.

Software Engineering Principles

Here are some basic principles that we’ll cover in this chapter:

• Involve your prospective users in the process as early and as often as possible.
• Build an initial, simple prototype and then add to it incrementally.
• Code and test in small increments, never more than a few blocks at a time.
• Design the logic for your app before beginning ...