How to increase lifetime of the bindings [duplicate] - rust

Question

This question already has answers here:
Extending borrowed lifetime for String slice
(2 answers)
Closed 5 years ago.
I have the following code ...
use std::process::Command;
fn main() {
let cmds = vec![vec!["ls", "-lh"], vec!["grep", "foo"]];
let mut processes: Vec<&mut Command> = Vec::new();
let mut i = 0;
let length = cmds.len();
while i < length {
let cmd = cmds[i].clone();
let mut p = Command::new(&cmd[0]).args(&(cmd[1..]));
processes.push(p);
i += 1;
}
println!("processes: {:?}", processes);
// want to manipulate processes elements here again.
// ...
}
Which doesn't compile:
error: borrowed value does not live long enough
--> src/main.rs:11:60
|
11 | let mut p = Command::new(&cmd[0]).args(&(cmd[1..]));
| --------------------- ^ temporary value dropped here while still borrowed
| |
| temporary value created here
...
19 | }
| - temporary value needs to live until here
|
= note: consider using a `let` binding to increase its lifetime
I understand why it refused to compile, I just don't know how to fix it in this case.

Answer 1

Instead of storing a borrowed reference, you could store the Command object itself.
let cmds = vec![vec!["ls", "-lh"], vec!["grep", "foo"]];
let mut processes: Vec<Command> = Vec::new();
// ^ you can store concrete objects instead of references.
for cmd in &cmds {
// ^ prefer a `for` loop over a `while` loop. (Also, you don't need to clone the cmds)
let mut p = Command::new(cmd[0]);
p.args(&cmd[1..]);
// ^ you can get a concrete `Command` instead of `&mut Command` reference
// if you store the returned object from `new()`.
processes.push(p);
}
println!("processes: {:?}", processes);
// processes: ["ls" "-lh", "grep" "foo"]