Mastering Rust - Second Edition

Statics

Statics are proper global values, as in they have a fixed memory location and exist as a single instance in the whole program. These can also be made mutable. However, as global variables are a breeding ground for the nastiest bugs out there, there are some safety mechanisms in place. Both reading and writing to statics has to be done inside an unsafe {} block. Here's how we crate and use statics:

// statics.rsstatic mut BAZ: u32 = 4; static FOO: u8 = 9; fn main() {    unsafe {        println!("baz is {}", BAZ);        BAZ = 42;        println!("baz is now {}", BAZ);        println!("foo is {}", FOO);    }}

In the code, we've declared two statics BAZ and FOO. We use the static keyword to create them along with specifying the type explicitly. If we want them to ...