3 ms·

Theres nothing special about unique_ptr, if you dont want allocations and youre ok with just moving your values around directly, you use value and move semantic

• School-Cotton 3y ago
  Move and value (deep copy) semantics exist in Rust too, but neither of those does the same thing as passing a raw pointer (or reference). Which you can do in c++, but not safely. That’s the difference with Rust. In C or C++ if a function/method takes a raw pointer (or some other lifetime-constrained type like string_view), I have no idea if it’s going to stash it somewhere and try to look at it again later. If it returns a raw pointer or reference, I don’t know whether it is going to get invalidated by some future call. Iterator invalidation is a huge source of UB in C++ but completely unknown in rust. Clearly having a hash map where all the values are stored indirectly in shared_ptr would let you provide a safe access API, but would be horrible for performance. In Rust you can have the safe API without compromising on efficiency.