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> How else would you implement C++’s vector::operator[] for example? Are you asking in a theoretical world where it isn’t defined to already return a `T&`?
by frutiger 2y ago
> How else would you implement C++’s vector::operator[] for example?
Are you asking in a theoretical world where it isn’t defined to already return a `T&`?
- blegr 2y agoNow that GP said it, it'd be nice to be able to write "some_map[i].value_or(some_value)".
- School-Cotton 2y agoYou can do this in rust with Vec::get, which returns an Option<&T>.
- School-Cotton 2y agoNo, that’s my point. It returns a reference. So it’s a good example of when you might want to return a reference, which you said seemed uncommon. But the reference it returns is unsafe (for example, it gets invalidated if the vector is later resized), whereas the reference returned by the corresponding Rust operator is safe.
- frutiger 2y agoSure, but the person I was relying to said they were writing code that returns references (not implementing the standard library). And my surprise was that they have to do it so often. My overall advice here would be that if you find yourself implementing vector-like data structures very often, then it is time to take a second look the design.
- School-Cotton 2y agoFair enough, but even if you’re not writing code like this, you still have to use it, so you’re still exposed to the unsafety.