How to declare a lifetime for a closure argument?

Question

I would like to declare a lifetime for a closure in Rust, but I can\'t find a way to add a lifetime declaration.

use std::str::SplitWhitespace;

pub struct P         


        

Answer 1

I don't know how to answer your question, but there are two ways to solve the problem:

The easiest one is to let the closure reference the iterator directly.

{
    let mut nt = || tokens.next().ok_or(missing_token(line_number));
    // call the closure as many times as you need to
}
    // At this point `tokens` will be usable again.

If you don't actually need do anything else with tokens afterwards, just do:

let mut nt = || tokens.next().ok_or(missing_token(line_number)); 

The other solution is to write a function that emulates what the closure is doing and call that instead.