Ask HN: Have you ever inherited a codebase nobody on the team could understand?

This is a big issue I run in to. I've spent the last ... 10 years working as an independent consultant, and am often brought in to projects which are... a mess. Almost by definition - if they were good and you could hire cheap people to make stuff 'work' you wouldn't be calling me in.

This assumption that "it's correct" is probably the biggest sticking point I hit, in various incarnations. Was just talking to a colleague this morning about rewrites vs refactoring. Whenever I go for a rewrite, there's issues, but the refactoring is almost always way way way way way underestimated.

Recently, came in to a project 3 months ago that is 5 years old, built with 2 different web frameworks merged together (as in 2 different set of session handler clobbering each other at seemingly random times), a mix of raw JS, jquery, angular and vue, 0 unit tests, 0 docs, things breaking, and the client/owners generally insist that things used to work like XYZ". No, they didn't. In fact, I can point out that XYZ never worked. You think it did, but it didn't.

There's this assumption in "never rebuild" that "don't do it... you're no smarter than the people who came before you, you'll make the same mistakes, or worse, those 'ugly parts' are there for a reason, etc". And yet... you' ALWAYS hear people say "don't ever roll your own crypto!". OK... well... at some point you have a conflict here, and you can argue for just 'refactor' away the crypto, but you may come to realize that every major tenant of secure/modern practices has been seriously violated.

I'm not only fighting code, I'm wrestling with a client who think things were working just fine, or "hey, we might need a little tweak on ABC here". No... digging in everywhere, I've found "oh, that report about 'this number changed' last month? - the numbers are calculated wrong, and have been for 4 years, but this is the first person to report it". Having one numeric field be treated as both 'immutable' by some section of the code, and 'live/updateable' by others...

If you have a full team of people who are dedicated who live/breath project X, and you're all on the same page, working fulltime towards a singular resolution... yes. Refactor. Agree on refactoring, schedules, priorities, etc.

> I strongly value the skill of reading code in engineers

If what you're reading ends up being the equivalent of "see dick run" level of code that's in charge of PII, and you're seeing spelling and grammar mistakes in what you're reading, there comes a point when you say "fixing this is not worth the time involved".

If this was a physical building or structure, and you determined that the foundations were so fundamentally bad and were constantly failing, or found that the materials used were misrepresented, you'd probably face some legal issues if you covered that up and kept building anyway.

If you're coming in to something that is clear the original team was in way over their head, you're facing multiple security issues, logic/data issues, have no tests, sample data, repeatable builds, and the project will take weeks to get to a rebuildable state, and conflicting/contradictory input from stakeholders... a fresh rebuild will likely make more sense. Take segments from previous code if you can extract them, but only when it makes sense.

What I'm wrestling with now is currently owning 4 years of technical debt on my own. "Person A before you used to get this done in just a few days... Person B always worked much faster". Well... yes, because they didn't test, didn't ever fix anything correctly, and I'm not plugging 15 holes at the same time, and every change uncovers 4 more critical data integrity issues. I could also work fast if I was ignorant about what I was doing, or just lied about what the impact would be. And hey - let's not have any tests to run at all, so there's never a quick way to validate if I'm telling the truth when I say "this won't impact anything".

The code had to be destroyed and started from scratch. It was absolutely unsalvageable.

is this not what awful is?

One, adopting necessary libraries that are lacking features, have way too many features, or questionable code quality. Examples have been an animated slideshow carousel, Python and PHP OAuth, and a WordPress theme. I thoroughly read the code for each of those, deleted the parts I didn’t need, and literally rearranged everything.

Then there are the times I go back to my code after a few years and have no idea what is going on. If possible, I just leave it alone if it’s working. Sometimes I need to use a new language or have developed a better coding style. In those cases I’ve rewritten it with a close eye to whatever edge cases I seem to be handling in the old code.