Working Effectively with Legacy Code

Chapter 19: My Project Is Not Object Oriented. How Do I Make Safe Changes?

The title of this chapter is a bit provocative. We can make safe changes in any language, but some languages make change easier than others. Even though object orientation has pretty much pervaded the industry, there are many other languages and ways of programming. There are rule-based languages, functional programming languages, constraint-based programming languages—the list goes on. But of all of these, none are as widespread as the plain old procedural languages, such as C, COBOL, FORTRAN, Pascal, and BASIC.

Procedural languages are especially challenging in a legacy environment. It’s important to get code under test before modifying it, but the number of things you ...