A borrowed variable was used by a closure.
Erroneous code example:
fn you_know_nothing(jon_snow: &mut i32) {
let nights_watch = &jon_snow;
let starks = || {
*jon_snow = 3; // error: closure requires unique access to `jon_snow`
// but it is already borrowed
};
println!("{}", nights_watch);
}
RunIn here, jon_snow
is already borrowed by the nights_watch
reference, so it
cannot be borrowed by the starks
closure at the same time. To fix this issue,
you can create the closure after the borrow has ended:
fn you_know_nothing(jon_snow: &mut i32) {
let nights_watch = &jon_snow;
println!("{}", nights_watch);
let starks = || {
*jon_snow = 3;
};
}
RunOr, if the type implements the Clone
trait, you can clone it between
closures:
fn you_know_nothing(jon_snow: &mut i32) {
let mut jon_copy = jon_snow.clone();
let starks = || {
*jon_snow = 3;
};
println!("{}", jon_copy);
}
Run