I’m slowly starting Rust for Rustaceans, and it’s already poking holes in my understanding of Rust. Here’s a couple initial questions I have:
A shared reference, &T is , as the name implies, a pointer that may be shared. Any number of references may exist to the same value, and each shared reference is Copy, so you can trivially make more of them
I don’t understand why a shared reference has to implement copy. In fact, isn’t this not true just by the fact that references work for Strings and Strings size can’t be known at compile time?
- I’m having trouble with the idea of assigning a new value to a mutable reference.
let mut x = Box::new(42); *x = 84;
Why in this example, is the assignment dereferenced. Why not just do x=84? is it dereferenced specifically because is Boxed on the heap?
In this context mutability is part of the type signatures. &T and &mut T are two different types, the former implements copy but not the later. It’s not really an “exception” in the type system.