> I pretty new to Rust and I’m wondering why global mutables are hard? They're n...

raggi · 2025-12-05T00:49:58 1764895798

People always complain about unsafe, so I prefer to just show the safe version.

  use std::sync::Mutex;

  static LIST: Mutex<Vec<String>> = Mutex::new(Vec::new());

  fn main() -> Result<(), Box<dyn std::error::Error>> {

      LIST.lock()?.push("hello world".to_string());
      println!("{}", LIST.lock()?[0]);

      Ok(())
  }

hu3 · 2025-12-05T22:46:51 1764974811

This is completely different from the previous example.

It doesn't increment anything for starters. The example would be more convoluted if it did the same thing.

And strings in rust always delivers the WTFs I need o na Friday:

    "hello world".to_string()

raggi · 2025-12-06T02:18:17 1764987497

    use std::sync::Mutex;
    fn main() -> Result<(), Box<dyn std::error::Error>> {
        static PEDANTRY: Mutex<u64> = Mutex::new(0);
        *PEDANTRY.lock()? += 1;
        println!("{}", PEDANTRY.lock()?);
        Ok(())
    }

hu3 · 2025-12-06T21:36:29 1765056989

Still different. Yours only increments once. Doesn't pass basic QA.

And declaring a static variable inside a function, even if in main, smells.

raggi · 2025-12-06T22:23:41 1765059821

OP you keep comparing to doesn't even declare the variable. I'm done with you.

umanwizard · 2025-12-07T17:31:00 1765128660

OP here, not showing how to declare the variable was an oversight on my part.

  static mut COUNTER: u32 = 0;

(at top-level)

If on 2024 edition, you will additionally need

  #![allow(static_mut_refs)]

raggi · 2025-12-07T18:07:13 1765130833

Yup, your example was fine, as I said I just wanted to show a safe method too :-)