February 5, 2025

Developer philosophy @ Things Of Interest

It's generally pretty well-understood that the ground-up rewrite can be an attractive and extremely dangerous prospect. The standard advice when it comes to ground-up rewrites is "Don't, ever". But I want to take a step back from that.

By the time the ground-up rewrite starts to seem like a good idea, avoidable mistakes have already been made. This is a scenario which you can see coming from a long way out and you can, and must, actively steer away from.

Warning signs to watch for: compounding technical debt. Increasing difficulty in making seemingly simple changes to code. Difficulty in documenting/commenting code. Difficulty in onboarding new developers. Dwindling numbers of people who know how particular areas of the codebase actually work. Bugs nobody understands.

Compounding complexity must be fought at every turn. Alternate between phases of expansion (new features) and consolidation.

Of course, a ground-up rewrite can actually work. It might even be a better choice that the alternative (persisting with your existing technical debt-laden swamp of code). Equally, it might be that neither choice will work — the project is doomed, and you're just choosing how it dies. The point is that there is inherent risk to this situation... but the situation itself is avoidable, and that risk is avoidable.

I love these "lessons learnt from x years of y" posts. This one rang true - you can see when complexity is building up - the heuristic of paying attention to when small changes take a lot of time / mental energy is a good one.