"sometimes" is doing a lot of work there.
Sometimes it is, but also sometimes it isn't, and Rust at least gives you a choice (you can use Arc all over the place, or if performance is critical you can be more careful about specifying lifetimes)
Sometimes it is, but also sometimes it isn't, and Rust at least gives you a choice (you can use Arc all over the place, or if performance is critical you can be more careful about specifying lifetimes)