GoF State Pattern vs FSM: Choosing the Right Tool for Complex Workflows

The classic Gang of Four State Pattern, while popular in textbooks and interviews, can create tightly coupled code when applied to complex real-world scenarios. In the GoF model, each state class must directly reference other state classes to trigger transitions, making the code harder to maintain as business rules grow. A Finite State Machine addresses this by centralising all transition rules in a single lookup structure, so individual state handlers remain unaware of each other. This approach makes it easier to add, remove, or modify states without breaking existing logic. Developers are advised to use the GoF pattern only for simple, closed-loop flows, and to prefer an FSM when transitions are event-driven, non-linear, or likely to change over time.