ABAP OOP Design Patterns — Part 2: Factory, Observer, and Decorator Patterns in Real SAP Systems

ABAP OOP Design Patterns — Part 2: Factory, Observer, and Decorator Patterns in Real SAP Systems If you’ve been writing ABAP long enough, you’ve probably inherited a codebase where every business rule is buried inside a 3,000-line function module, and adding a new requirement means copy-pasting logic you’re not even sure is correct. That’s not a skills problem — it’s an architecture problem. In Part 1 of this series, we explored how the Strategy Pattern helps you swap business logic cleanly without touching the calling code. Now it’s time to go further. In this second installment, we’re tackling three more battle-tested ABAP OOP design patterns: Factory, Observer, and Decorator. Each one solves a very specific pain point I’ve encountered repeatedly across large SAP S/4HANA implementations — and I’ll show you exactly how to apply them. Before we dive in, a quick note: these patterns aren’t academic exercises. Every example below is inspired by real implementation challenges on productio