Example
All values in Rust have a lifetime. A value's lifetime spans the segment of code from the value is introduced to where it is moved, or the end of the containing scope
{
let x = String::from("hello"); // +
// ... :
let y = String::from("hello"); // + |
// ... : :
foo(x) // x is moved | = x's lifetime
// ... :
} // = y's lifetime
Whenever you borrow a value, the resulting reference has a lifetime that is tied to the lifetime of the value being borrowed:
{
let x = String::from("hello");
let y = String::from("world");
// when we borrow y here, the lifetime of the reference
// stored in foo is equal to the lifetime of y
// (i.e., between let y = above, to the end of the scope below)
let foo = &y;
// similarly, this reference to x is bound to the lifetime
// of x --- bar cannot, for example, spawn a thread that uses
// the reference beyond where x is moved below.
bar(&x);
}
