Rust by Example

fn main() { // Assign a reference of type `i32`. The `&` signifies there // is a reference being assigned. let reference = &4; match reference { // If `reference`s is pattern matched against `&val`, it results // in a comparison like: // `&i32` // `&val` // ^ We see that if the matching `&`s are dropped, then the `i32` // should be assigned to `val`. &val => println!("Got a value via destructuring: {:?}", val), } // To avoid the `&`, you dereference before matching. match *reference { val => println!("Got a value via dereferencing: {:?}", val), } // What if you don't start with a reference? `reference` was a `&` // because the right side was already a reference. This is not // a reference because the right side is not one. let _not_a_reference = 3; // Rust provides `ref` for exacty this purpose. It modifies the // assignment so that a reference is created for the element; this // reference is assigned. let ref _is_a_reference = 3; // Accordingly, by defining 2 values without references, references // can be retrieved via `ref` and `ref mut`. let value = 5; let mut mut_value = 6; // Use `ref` keyword to create a reference. match value { ref r => println!("Got a reference to a value: {:?}", r), } // Use `ref mut` similarly. match mut_value { ref mut m => { // Got a reference. Gotta dereference it before we can // add anything to it. *m += 10; println!("We added 10. `mut_value`: {:?}", m); }, } }