[Rust] Intro Lifetimes

The following code has compiler error:

fn jazz(years: &[i64]) -> Releases {
    let eighties: [i64] = &years[0..2];
    let nineties: [i64] = &years[2..4];
    
    Releases {
        years,
        eighties,
        nineties,
    }
}

let releases = {
   let all_years: Vec<i64> = vec![
      1980, 1985, 1990, 2000, 2005 
   ];
   jazz(&all_years)
}; //dealloc(all_years)

let eighties = releases.eighties;

Mainly due to after calling jazz(&all_years), Rust dealloc all_years, later when we try to refer to releases.eighties, it doesn't exist anymore.

 

To resolve the problem, we need to intro lifetime to help us to analysis the code:

// Named lifetime as all_years
fn jazz<'all_years>(years: &'all_years [i64]) -> Releases<'all_years> {
    let eighties: &'all_years [i64] = &years[0..2];
    let nineties: &'all_years [i64] = &years[2..4];
    
    Releases {
        years,
        eighties,
        nineties,
    }
}

// lifetime to struct
struct Releases<'years> {
   years: &'years [i64],
   eighties: &'years [i64],
   nineties: &'years [i64],
}

let releases = {
   let all_years: Vec<i64> = vec![
      1980, 1985, 1990, 2000, 2005 
   ];
   jazz(&all_years)
}; //dealloc(all_years)

let eighties = releases.eighties;