composition.rs

fn main() {
    let mut c = CompoundGraphics::new();
    c.add_all(vec![
        Box::new(Dot {
            x: 100,
            y: 200,
        }),
        Box::new(Rectangle {
            x: 200,
            y: 300,
            width: 30,
            height: 40,
        }),
    ]);
    c.draw();
}

trait Graphics {
    fn moved(&mut self, x: i32, y: i32);
    fn draw(&self);
}


struct CompoundGraphics<'a> {
    children: Vec<Box<dyn Graphics + 'a>>,
}

impl<'a> CompoundGraphics<'a> {
    fn new() -> Self {
        Self {
            children: Vec::new()
        }
    }

    fn add_all(&mut self, shapes: Vec<Box<dyn Graphics>>) {
        self.children.extend(shapes);
    }
}


impl Graphics for CompoundGraphics<'_> {
    fn moved(&mut self, _: i32, _: i32) {}

    fn draw(&self) {
        for child in &self.children {
            child.draw();
        }
    }
}

struct Dot {
    x: i32,
    y: i32,
}

impl Graphics for Dot {
    fn moved(&mut self, x: i32, y: i32) {
        self.x = x;
        self.y = y;
    }

    fn draw(&self) {
        println!("Dot::draw(x: {}, y: {},)", self.x, self.y);
    }
}

struct Rectangle {
    x: i32,
    y: i32,
    width: i32,
    height: i32,
}

impl Graphics for Rectangle {
    fn moved(&mut self, x: i32, y: i32) {
        self.x = x;
        self.y = y;
    }

    fn draw(&self) {
        println!(
            "Rectangle::draw(x: {}, y: {}, width: {}, height:{})",
            self.x, self.y, self.width, self.height
        );
    }
}