原型

use std::any::Any;

//Shape is Prototype
trait Shape {
    fn clone(&self) -> Box<dyn Shape>;

    fn as_any(&self) -> &dyn Any;
}

//Square is ConcretePrototype
#[derive(Debug)]
struct Square {
    line_count: i32
}

impl Shape for Square {
    fn clone(&self) -> Box<dyn Shape> {
        Box::from(Square {
                line_count: self.line_count
        })
    }

    fn as_any(&self) -> &dyn Any { self }    
}

//ShapeMaker contains a Shape
struct ShapeMaker {
    shape: Box<dyn Shape>
}

//MakeShape creates a copy of the Shape
impl ShapeMaker {
    fn make_shape(&self) -> Box<dyn Shape> {
        Box::from(self.shape.clone())
    }
}

//Client
let square = Square{ line_count: 4 };
let maker = ShapeMaker{ 
    shape: Box::from(square) };

let square1 = maker.make_shape();
let square2 = maker.make_shape();

println!("square1 is {:?}", square1.as_any()
    .downcast_ref::<Square>().unwrap());
println!("square2 is {:?}", square2.as_any()
    .downcast_ref::<Square>());