main.rs

struct MyVec<T>(T);

impl fmt::Display for MyVec<&Vec<i32>> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "[");

        for (i, el) in *(self.0).iter().enumerate() {
            if i != 0 {
                write!(f, ", ");
            }
            write!(f, "{}", el);
        }

        write!(f, "]")
    }
}

fn main() {
    let mut vec = vec![1, 2, 3];
    {
        let _vec = MyVec(&vec);
        println!("{}", _vec);
    }
    
    vec.push(4);
    {
        let _vec = MyVec(&vec);
        println!("{}", _vec);
    }
}

stdout

-*- mode: cargo-process; default-directory: "~/scratch/" -*-
Cargo-Process started at Sun Jul  9 16:58:47

cargo bench
   Compiling scratch v0.1.0 (file:///home/arrdem/scratch)
error[E0106]: missing lifetime specifier
  --> src/main.rs:39:29
   |
39 | impl fmt::Display for MyVec<&Vec<i32>> {
   |                             ^ expected lifetime parameter

error: aborting due to previous error

error: Could not compile `scratch`.

To learn more, run the command again with --verbose.

Cargo-Process exited abnormally with code 101 at Sun Jul  9 16:58:47