Learn Rust in a Month of Lunches

10 Lifetimes and interior mutability

This chapter covers

• Types of &str (there’s more than one)
• Using lifetime annotations to help the compiler know how long a reference lives
• Using interior mutability, which provides safe mutability without &mut

It is now time to learn about Rust’s famous lifetimes, used by the compiler to know when variables can be dropped and how long references last. Usually, you don’t need to specify lifetimes in your code, but sometimes the compiler needs a bit of help and will ask you to tell it how long something should last. We are also going to learn how to (safely!) mutate values without needing a mutable reference to do it!

10.1 Types of &str

We’ve been using &str for most of the book so far. But here’s an interesting ...