4 ms·

It would probably take several years to do a full rewrite of a complicated system, and there'd be subtle differences all over the place.

• db48x 3y ago
  Then you don’t have good enough documentation or tests, and you probably tried to rewrite too much. You should rewrite that portion of your code where the performance is most critical, because that’s where you will save the most money.
  • bombolo 3y ago
    Have you even worked with a big complicated legacy system whose authors have all quit?
    • db48x 3y ago
      Yes. A good example would be Firefox. Mozilla is gradually replacing core components of Firefox with replacements written in Rust. It is not cheap to do this without causing regressions, but they have a great test suite and they know that it will save money in the long run. It increases performance, decreases memory usage, and most importantly it greatly reduces the defect rate. They’ll probably never bother to replace _all_ of the C++ code with Rust, because a lot of it works well or isn’t security–critical. They’ve been doing this since Rust 1.0, with measurable improvements in every release of the last few years.