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> Javascript VM´s these days are fairly complex beasts with huge amount of man-hour and expertise. You know what else is a MASSIVE time and money sink? C/C++.

by mamcx 7y ago

> Javascript VM´s these days are fairly complex beasts with huge amount of man-hour and expertise. You know what else is a MASSIVE time and money sink? C/C++. Combining 2 big and nasty complex stuff you get something even bigger. ---- I don't say to blind rewrite. Is know to be: > an exercize in vanity and why not say it, stupidity. But this must take in account TIME. Right now, is not the time for a rewrite, but is better to have it planned. ---- I'm not naive saying this. This is my life (as a rewriter of codebases for several years and many projects). I'm moving a medium sized ERP project to Rust. In parts, too. Focusing in data exchange, yes. But if we don't do it, then the complexity behind will kill us.

pjmlp 7y ago
Depends, using WinUI, Qt or Gtkmm is way faster than Gtk-rs, regarding productivity.
oscargrouch 7y ago
The topic of rewrite, i think it depends a lot of the context. Some things might make perfect sense for a rewrite, but i still think that a very optimized with huge amount of man-hour piece of sophisticated and complex C++ codebase like Spidermonkey VM are not one of those things. Theres no gain in clear performance, unless theres a better algorithm being implemented, no clear gain in productivity, as C++ and Rust are both equaly complex beasts, and with not much gain in security, if you already implemented in "modern c++" and are using smart pointers, including in API´s and moves correctly. The other gains in security/safety that you might have with Rust, are maybe lost if you think that the C++ codebase have been used and tested in every possible scenario, so a lot of bugs are corrected, and if you think that given this is a Jit VM you will have to use Rust´s unsafe{} in a lot of places, i still think, giving the context, that is not a smart thing to do, and it will be more like a trophy to Rust, but without a more pragmatic and realistic approach to the matter, not focusing properly on results. Not much gain, you will end with a worse and more buggy JIT in the end, and will have to spend more years, only to get parity to the VM you already had in the first place.
- mamcx 7y ago
  That is correct, in the SHORT time. The thing with rust is that it provide safety guarantee FOREVER. Is like null. You can write null-safe code in any language... as long your developers become "compilers" and by discipline make sure EVERY LINE is null safe. But when your lang do it for you, is a problem that get solved. C++ demand a lot of attention to details that are unnecessary in rust. This is where the gain come.

by mamcx 7y ago

pjmlp 7y ago

Depends, using WinUI, Qt or Gtkmm is way faster than Gtk-rs, regarding productivity.

oscargrouch 7y ago

The topic of rewrite, i think it depends a lot of the context. Some things might make perfect sense for a rewrite, but i still think that a very optimized with huge amount of man-hour piece of sophisticated and complex C++ codebase like Spidermonkey VM are not one of those things. Theres no gain in clear performance, unless theres a better algorithm being implemented, no clear gain in productivity, as C++ and Rust are both equaly complex beasts, and with not much gain in security, if you already implemented in "modern c++" and are using smart pointers, including in API´s and moves correctly. The other gains in security/safety that you might have with Rust, are maybe lost if you think that the C++ codebase have been used and tested in every possible scenario, so a lot of bugs are corrected, and if you think that given this is a Jit VM you will have to use Rust´s unsafe{} in a lot of places, i still think, giving the context, that is not a smart thing to do, and it will be more like a trophy to Rust, but without a more pragmatic and realistic approach to the matter, not focusing properly on results. Not much gain, you will end with a worse and more buggy JIT in the end, and will have to spend more years, only to get parity to the VM you already had in the first place.

mamcx 7y ago
That is correct, in the SHORT time. The thing with rust is that it provide safety guarantee FOREVER. Is like null. You can write null-safe code in any language... as long your developers become "compilers" and by discipline make sure EVERY LINE is null safe. But when your lang do it for you, is a problem that get solved. C++ demand a lot of attention to details that are unnecessary in rust. This is where the gain come.