Guru: Cohesion First – What A Procedure Should Be Responsible For
April 6, 2026 Gregory Simmons
One of the easiest mistakes to make in procedure-driven RPG is assuming that small procedures are automatically well-designed procedures. They are not. Size and cohesion are related, but they are not the same thing. A cohesive procedure has a single, clear responsibility. It exists to answer one business question or perform one business action. When a procedure tries to do more than that, it stops being a reusable building block and starts becoming a liability.
In procedural RPG, nothing enforces this discipline. There is no compiler warning when a procedure quietly takes on a second responsibility. There is no language …
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There has never been anything wrong with IBM i job logs themselves. They are exhaustive, consistent, and remarkably detailed. When something fails, the job log contains the truth. The issue has always been consumption. Large QPJOBLOG files can run thousands of lines (or