Hands-on Rust

Rendering with Themes

The MapBuilder needs to know what theme you’re associating with your newly designed map. Open map_builder/mod.rs, and add a theme to the MapBuilder:

MapTheming/themed/src/map_builder/mod.rs

const NUM_ROOMS: usize = 20;
pub struct MapBuilder {
    pub map : Map,
    pub rooms : Vec<Rect>,
    pub monster_spawns : Vec<Point>,
    pub player_start : Point,
    pub amulet_start : Point,
    pub theme : Box<dyn MapTheme>
}

If you’re using an IDE, it probably just highlighted all of your map builders as compilation errors. These errors happen because you’ve extended MapBuilder to include a new field. Rust requires that you initialize every field in a struct on creation—uninitialized fields are a common source of bugs ...