Let's start with the basic Cell structure. A Cell will contain a mutable value, but it can be mutated without having a mutable Cell. It has mainly three interesting methods: set(), swap(), and replace(). The first allows us to set the contained value, replacing it with a new value. The previous structure will be dropped (the destructor will run). That last bit is the only difference with the replace() method. In the replace() method, instead of dropping the previous value, it will be returned. The swap() method, on the other hand, will take another Cell and swap the values between the two. All this without the Cell needing to be mutable. Let's see it with an example:
use std::cell::Cell;#[derive(Copy, Clone)]struct House { bedrooms: ...