What is a lifetime in Rust?
One of the most distinguished traits of Rust is that the majority of errors are handled during compile-time. Rust’s compiler has a Borrow Checker that compares scopes (aka lifetimes) of variables and their references to avoid invalid memory access during run-time.
For example, consider the code below; it does not compile because the reference,x, has a larger scope than the subject of the reference, y. This is why we get the error message "y does not live long enough."
fn main() {let x; //--------+(a){ // |let y = 2; //--+(b) |x = &y; // | |} //--+ |} //--------+
If the subject of the reference has a larger lifetime than the reference variable, the program will compile. As an example, let’s swap variables x and y to get rid of the error:
fn main() {let x = 2; //--------+(a){ // |let y = &x; //--+(b) |} //--+ |} //--------+
Since the subject (x) has a larger lifetime than the reference (y), the program compiles successfully.
