-// Rust-101, Part 04: Ownership, Borrowing
-// =======================================
+// Rust-101, Part 04: Ownership, Borrowing, References
+// ===================================================
/*
void foo(std::vector<int> v) {
/* println!("The first element is: {}", v[0]); */ /* BAD! */
}
-// ## Shared borrowing
+// ## Borrowing a shared reference
fn vec_min(v: &Vec<i32>) -> Option<i32> {
use std::cmp;
let mut min = None;
- // This time, we explicitly request an iterator for the vector `v`. The method `iter` borrows the vector
- // it works on, and provides shared borrows of the elements.
+ // This time, we explicitly request an iterator for the vector `v`. The method `iter` just borrows the vector
+ // it works on, and provides shared references to the elements.
for e in v.iter() {
// In the loop, `e` now has type `&i32`, so we have to dereference it to obtain an `i32`.
min = Some(match min {
}
// Now that `vec_min` does not acquire ownership of the vector anymore, we can call it multiple times on the same vector and also do things like
-fn shared_borrow_demo() {
+fn shared_ref_demo() {
let v = vec![5,4,3,2,1];
let first = &v[0];
vec_min(&v);
println!("The first element is: {}", *first);
}
-// ## Mutable borrowing
+// ## Unique, mutable references
fn vec_inc(v: &mut Vec<i32>) {
for e in v.iter_mut() {
}
}
// Here's an example of calling `vec_inc`.
-fn mutable_borrow_demo() {
+fn mutable_ref_demo() {
let mut v = vec![5,4,3,2,1];
/* let first = &v[0]; */
vec_inc(&mut v);
// The ownership and borrowing system of Rust enforces the following three rules:
//
// * There is always exactly one owner of a piece of data
-// * If there is an active mutable borrow, then nobody else can have active access to the data
-// * If there is an active shared borrow, then every other active access to the data is also a shared borrow
+// * If there is an active mutable reference, then nobody else can have active access to the data
+// * If there is an active shared reference, then every other active access to the data is also a shared reference
//
// As it turns out, combined with the abstraction facilities of Rust, this is a very powerful mechanism
// to tackle many problems beyond basic memory safety. You will see some examples for this soon.