Sharing ownership with smart pointers

Some ownership relationships are not as straightforward as type A owns B. Sometimes, an entire group of types owns another type. To handle this, we need another smart pointer that behaves mostly like Box but only deletes the underlying resource if no one needs it anymore, it is Rc, which stands for Reference Counted.

How to do it...

1. In the bin folder, create a file called shared.rs

2. Add the following code and run it with cargo run --bin shared:

1    use std::rc::Rc;
2 
3    // The ball will survive until all kids are done playing with 
        it
4    struct Kid {
5      ball: Rc<Ball>,
6    }
7    struct Ball;
8 
9    fn main() {
10     {
11       // rc is created and count is at 1
12       let foo = Rc::new("foo");
13       // foo goes out of scope; count decreases
14       // count is zero; the object gets destroyed
15     }
16 
17     {
18       // rc is created and count is at 1
19       let bar = Rc::new("bar");
20       // rc is cloned; count...