Clone

Sometimes you want to make a copy of a value. The Clone trait accomplishes this.

# // Copyright 2023 Google LLC
# // SPDX-License-Identifier: Apache-2.0
#
fn say_hello(name: String) {
    println!("Hello {name}")
}

fn main() {
    let name = String::from("Alice");
    say_hello(name.clone());
    say_hello(name);
}

• The idea of Clone is to make it easy to spot where heap allocations are occurring. Look for .clone() and a few others like vec! or Box::new.

• It's common to "clone your way out" of problems with the borrow checker, and return later to try to optimize those clones away.

• clone generally performs a deep copy of the value, meaning that if you e.g. clone an array, all of the elements of the array are cloned as well.

• The behavior for clone is user-defined, so it can perform custom cloning logic if needed.