My girlfriend in Rust

Some people don’t like to say “my girlfriend”. They think it implies ownership over the person. Lets explore that using Rust. Swap genders at will.

struct Human {
    name: str
    // ???
}

Even though Rust is not object oriented, I’m sorry for objectifying Alice here.

let bobs_girlfriend = Human { name: "Alice", /* ??? */ };

This is what some people think when they hear “my girlfriend”, Bob owns Alice in this cenario.

let charlies_friend = &bobs_girlfriend;

Charlie can only borrow Alice, Bob maintains ownership of Alice, the compiler enforces monogamy.

That is not how it works, lets try again.

use std::rc::Rc;
use std::option;

let alice = Rc::new(Human { name: "Alice", /* ??? */ });

The name “Alice” refers to Alice, who is now owned by the reference counter. In this digital world it’s like a god, it decides who lives and dies.

let mut bobs_girlfriend = Some(alice.clone());

“Bobs girlfriend” is a reference to Alice, no more or less than the name “Alice”. Bob owns the reference, but not Alice.

assert!(*alice == *(bobs_girlfriend.unwrap()));

“Alice” and “Bobs girlfriend” are the same thing, though the latter is mutable and optional.

assert!(*(bobs_girlfriend.unwrap()).beautiful == true);

This throws a compiler error; Beauty is in the eye of the beholder.

let mut charlies_girlfriend = Some(alice.clone()); // Polygamy

Charlie does not own Alice either.

charlies_girlfriend = None
bobs_girlfriend = None

If you are forgotten, do you cease to exist? Better not find out. Love the ones dear to you. You’ll never know when they will be garbage collected.