Rust closures from factory functions

Question

I have some Rust code I\'m trying to get working but I\'m not sure how to go about it.

fn main() {
    let names = vec![\"foo\", \"bar\", \"baz\"];
    let p         


        

Answer 1

The error says that names must outlive the static lifetime, this is because the boxed Fn has static lifetime. You have two options:

1. Add the 'static lifetime to names:

   fn printer(names: Vec<&'static str>) -> Box<Fn() -> String>{
       Box::new(move|| {
           // ...
       })
   }
   

2. Change the lifetime of the boxed Fn to match the names lifetime:

   fn printer<'a>(names: Vec<&'a str>) -> Box<Fn() -> String + 'a>{
       Box::new(move|| {
           // ...
       })
   }
   

Note that the body of closure needs to be adjusted and that you are giving the ownership of names to printer, so you cannot use names in do_other_thing. Here is a fixed version:

fn main() {
    let names = vec!["foo", "bar", "baz"];
    let print = printer(&names);
    let result = print();
    println!("{}", result);
    do_other_thing(names.as_slice());
}

fn printer<'a>(names: &'a Vec<&str>) -> Box<Fn() -> String + 'a>{
    Box::new(move || {
        // this is more idiomatic
        // map transforms &&str to &str
        names.iter().map(|s| *s).collect()
    })
}