Guru: Assertions, Take 2

February 12, 2024 Ted Holt

It’s been almost 20 years since Cletus the Codeslinger introduced assertions to the IBM midrange world, and in that time, I have included many assertions in my RPG programs. During that 20 years, RPG has changed a bit and Cletus has quit writing articles (but not source code), so I’ve taken it upon myself to update the code he gave us.

First, however, it might be a good idea to briefly review the topic of assertions for readers who don’t know what they are. An assertion is a program statement or command that cancels a program if a fatal condition …