3 ms·

For self-referential datastructures (your first point above), using an Rc or Arc shouldn't have any overhead. I agree that it would be nice to be able to expres

by Jonhoo 10y ago

For self-referential datastructures (your first point above), using an Rc or Arc shouldn't have any overhead. I agree that it would be nice to be able to express this, but it's not really that big of a problem. For partial borrows, there has been some work on it (https://github.com/rust-lang/rfcs/issues/1215 https://github.com/rust-lang/rfcs/issues/1215), but I agree that this is something that's missing. That said, I very rarely run into this, and there's usually some fairly obvious restructuring I can do to make it work out.

steveklabnik 10y ago
Also, the owning_ref crate can help.
scottlamb 10y ago
> For self-referential datastructures (your first point above), using an Rc or Arc shouldn't have any overhead. I agree that it would be nice to be able to express this, but it's not really that big of a problem. I don't see how that could be true. It means using a separate heap allocation for each referenced piece (although the owning_ref thing steveklabnik mentioned might minimize that), a bit of extra RAM for the counter, and a bit of bookkeeping. I'm not saying the overhead is huge, but how could it be zero? fwiw, I finished this section of my code, and the context approach I mentioned worked out well for me. It was just a bit of a puzzle to find a way Rust would like. I'm pretty happy with Rust so far even though I've had to restructure parts of an apparently-working program to fit its model. My program is now more obviously correct, benchmarks are pretty good so far (though I wish profile-driven optimization were supported/mature: https://unhandledexpression.com/2016/04/14/using-llvm-pgo-in-rust/ https://unhandledexpression.com/2016/04/14/using-llvm-pgo-in...), and the open source library situation seems better than C/C++ for what I'm doing and actively improving where C/C++ is stagnant.

by Jonhoo 10y ago

steveklabnik 10y ago

Also, the owning_ref crate can help.

scottlamb 10y ago

> For self-referential datastructures (your first point above), using an Rc or Arc shouldn't have any overhead. I agree that it would be nice to be able to express this, but it's not really that big of a problem. I don't see how that could be true. It means using a separate heap allocation for each referenced piece (although the owning_ref thing steveklabnik mentioned might minimize that), a bit of extra RAM for the counter, and a bit of bookkeeping. I'm not saying the overhead is huge, but how could it be zero? fwiw, I finished this section of my code, and the context approach I mentioned worked out well for me. It was just a bit of a puzzle to find a way Rust would like. I'm pretty happy with Rust so far even though I've had to restructure parts of an apparently-working program to fit its model. My program is now more obviously correct, benchmarks are pretty good so far (though I wish profile-driven optimization were supported/mature: https://unhandledexpression.com/2016/04/14/using-llvm-pgo-in-rust/ https://unhandledexpression.com/2016/04/14/using-llvm-pgo-in...), and the open source library situation seems better than C/C++ for what I'm doing and actively improving where C/C++ is stagnant.