Rust Programming By Example

Reference-counting pointer

We'll also change some code before we continue. Since we'll want to share our Playlist widget with different parts of our code, including some event handlers, we need a way of sharing a reference that will last long enough (remember the issue we had with the lifetime). One easy way of doing so is to use a reference-counting pointer type—Rc. So, in our App structure, let's change the playlist field to use an Rc:

struct App {
    adjustment: Adjustment,
    cover: Image,
    playlist: Rc<Playlist>,
    toolbar: MusicToolbar,
    window: Window,
}

This requires a new import at the top of the main module:

use std::rc::Rc;

Also, the creation of the playlist needs to be updated:

let playlist = Rc::new(Playlist::new());

We now wrap the