Using relm on stable Rust

In this whole chapter, we used Rust nightly to be able to use custom attributes, which are currently unstable. The #[widget] attribute provided by relm provides many advantages:

• Declarative view
• Data bindings
• Less typing

So it would be nice to be able to use a similar syntax on stable that provides the same advantages. And it is possible to do so, by using the relm_widget! macro. We'll rewrite the App widget to use this macro:

relm_widget! {
    impl Widget for App {
        fn init_view(&mut self) {
            self.toolbar.show_all();
        }

        fn model() -> Model {
            Model {
          adjustment: Adjustment::new(0.0, 0.0, 0.0, 0.0, 0.0, 0.0),
                cover_pixbuf: None,
                cover_visible: false,
                current_duration: 0,
                current_time: 0,
                play_image: new_icon(PLAY_ICON),
                stopped: true,
            }
        }

        fn open(&self) {
            // …
     ...