←
Beta
Home

Now that we know a little bit about trait objects and how to work with them, let's use them in a different example, this challenge focuses on using Box<dyn Trait> as fields in structs to encapsulate objects with dynamic behavior.

Your Task

You need to define a trait called Renderable and create two structs, Circle and Rectangle, that implement this trait. Then, you will create another struct called Canvas, which can hold a collection of objects implementing the Renderable trait. The Canvas struct should have methods to add objects and render all objects.

Requirements

Here are the requirements for the program, make sure to read them carefully:

Define the Renderable Trait

  • The trait should have a method render(&self) -> String to represent the object visually.

Define the Circle and Rectangle Structs

  • Circle should have a radius: f64 field.
  • Rectangle should have width: f64 and height: f64 fields.

Implement the Renderable Trait

  • For Circle, the render method should return a string like "Circle with radius X".
  • For Rectangle, the render method should return a string like "Rectangle with width X and height Y".

Define the Canvas Struct

  • The struct should have a shapes field that can store a Vec of the Renderable trait objects.
  • Implement the following methods for Canvas:
    • new() -> Canvas: Initializes an empty canvas.
    • add_shape(): Adds a shape to the canvas.
    • render_all(): Returns a vector of strings, each representing a rendered shape.

⚠️ Make sure you make all the relevant items public with the pub keyword, this is required for the tests to work.

Hints

If you're stuck, here are some hints to help you solve the challenge:

<details> <summary>Click here to reveal hints</summary>
  • Use Box<dyn Trait> to store objects with dynamic behavior. e.g. 
    pub struct Canvas {
      pub shapes: Vec<Box<dyn Renderable>>,
    }
</details>
← PreviousNext →
pub trait Renderable {
    fn render(&self) -> String;
}


pub struct Circle {
    pub radius: f64,
}


pub struct Rectangle {
    pub width: f64,
    pub height: f64,
}


// 1. Implement the trait for Circle and Rectangle


// 2. Create the Canvas struct


// 3. Implement the Canvas struct


// Example usage
pub fn main() {
    let mut canvas = Canvas::new();
    canvas.add_shape(Box::new(Circle { radius: 5.0 }));
    canvas.add_shape(Box::new(Rectangle {
        width: 3.0,
        height: 4.0,
    }));
    let rendered_shapes = canvas.render_all();
    for shape in rendered_shapes {
        println!("{}", shape);
    }
}