[neocritter]

A classic: https://www.joelonsoftware.com/2000/04/06/things-you-should-...

>> "The idea that new code is better than old is patently absurd. Old code has been used. It has been tested. Lots of bugs have been found, and they’ve been fixed. There’s nothing wrong with it. It doesn’t acquire bugs just by sitting around on your hard drive."

>> "Each of these bugs took weeks of real-world usage before they were found. The programmer might have spent a couple of days reproducing the bug in the lab and fixing it. If it’s like a lot of bugs, the fix might be one line of code, or it might even be a couple of characters, but a lot of work and time went into those two characters."

>> "When you throw away code and start from scratch, you are throwing away all that knowledge. All those collected bug fixes. Years of programming work."

It's an older piece, but like good old code, it still holds up. Newer tools and technology have improved the creating of new code, but they've also made improving old code easier in equal measure.

[silotis]

It's a good point in general, but in this case it's not clear if the cost of re-writing the existing codebase is less than the cost of staying with a memory-unsafe language.

We know from past experience that it takes an extreme amount of time and effort to harden a browser written in C++ against malicious web content. The Ladybird codebase is not particularly "old" in any sense of the word. Judging by Github's stats most of the code is less than 4 years old and it is still a long ways from being ready for general use. I think it's safe to say Ladybird still has a vast amount of work to be done fixing vulnerabilities that arise from lack of memory safety.

I find it quite plausible that the cost of re-writing the existing code in Rust is less than the cost of fixing all of the current and future bugs in the C++ codebase that Rust would catch at compile time.

[neocritter]

That is the sneaky thing about rewrites. The "Ship of Theseus" rewrite is reasonably safe based on the article and what I could find of people sharing their experiences with rewrites. Fix what needs fixing, but swap in the newer better language/framework/whatever a piece at a time. It works!

People get in trouble when they decide to rewrite the whole thing. You might be right in this case, but I'm sure every person who began a doomed rewrite project felt the the benefits outweighed the risks.

Viewed in the rear view mirror of history, the Netscape rewrite was a good thing in a technical sense. As far as I understand it gave us the foundation for Firefox and the Gecko engine. It was just bad business in context because it let other browsers run laps around it while the rewrite proceeded. It let IE get a foothold that didn't shake for many years until Netscape became Firefox.

Rewriting the new browser in Rust would probably be similar from a technical POV. But from a business standpoint, we seem to be at an inflection point where a new browser might be able to enter in the cracks of discontent over sketchy AI features in Edge and the slow-boiling attempts to break ad blocking in Chrome. If they divert resources now to a rewrite, they could miss this opportunity to do to Chrome what Firefox did to IE.

It sounds like the plan is a Ship of Theseus rewrite anyway, so they'll get there in time without the risk of distraction.

[noduerme]

The only exception is if you have 500k LOC in a language whose runtime is going to be deprecated on all platforms overnight.

I'm referring to the uh, retrospectively unfortunate decision I made in 2007 to start building large scale business app frontends in AS3.

I guess I should be thankful for the work, having to rewrite everything in TS from scratch a decade later. (At least the backends didn't have to be torn down).

[neocritter]

There's a parallel universe where someone convinced you to rewrite it in something else from the start and you spent years on the rewrite instead and it never went anywhere. Could you have done that emergency rewrite without 10 years of becoming an expert in the problem you were solving? The alternative universe has you spending time becoming an expert in a new language instead and maybe not getting anywhere with the rewrite.

[Tade0]

I wonder how many businesses suffered the same?

I remember Flash as a complete, straight-to-business platform that allowed me to just focus on getting stuff done.

It was a sound decision back then.

[voidwtf]

My current employer, similarly, invested a significant amount of resources into Silverlight. Luckily only one component of the application had been switched to Silverlight, but a significant amount of code was written to be the core of that effort and future components before browsers/MS killed it overnight.

[8474_s]

Old code does acquire new bugs by sitting in your hard drive, since it interfaces with dozens of libraries and APIs that don't care about how well test the code is: every path of code is dependent on multiple components playing well and following standards/APIs/formats that old code has no knowledge of. Also, the mountain of patch-fixes and "workarounds" in the end force the programmers into a corner, where development is hobbled by constraints and quirks of "battle-tested" code, that will be thrown away as soon as it couldn't support fancy new feature X or cannot use fancy new library API without extra layers of indirection.