Rust Struct Lifetime

main.rs

#![allow(unused)]

use std::fmt;

#[derive(Copy, Clone)]
pub struct Type<'a> {
    mime_type: &'a str,
}

impl<'a> Type<'a> {
    pub(crate) const fn new(mime_type: &'a str) -> Self {
        Self { mime_type }
    }

    pub const fn mime_type(&self) -> &'a str {
        self.mime_type
    }
}

impl fmt::Debug for Type<'_> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Kind")
            .field("mime_type", &self.mime_type)
            .finish()
    }
}

pub struct Infer<'a> {
    mmap: Vec<Type<'a>>,
}

impl<'a> Infer<'a> {
    pub const fn new() -> Infer<'a> {
        Infer { mmap: Vec::new() }
    }

    pub fn add(&mut self, mime_type: &'a str) {
        self.mmap.push(Type::new(mime_type));
    }

    pub fn get_first(&self) -> &'a Type {
        &self.mmap[0]
    }
}

fn main() {
    let mut i = Infer::new();
    i.add("foo");
    println!("first: {:?}", i.get_first());
}