e027: Trust Me; I Promise!

New Rustacean

Contenido proporcionado por Chris Krycho. Todo el contenido del podcast, incluidos episodios, gráficos y descripciones de podcast, lo carga y proporciona directamente Chris Krycho o su socio de plataforma de podcast. Si cree que alguien está utilizando su trabajo protegido por derechos de autor sin su permiso, puede seguir el proceso descrito aquí https://es.player.fm/legal.

6y ago 21:27

MP3•Episodio en casa

An intro to unsafe Rust and Rust’s idea of safety.

Show Notes

Errata

A quick correction: on the show I said that a trait needed to be unsafe when it had an unsafe fn method. This isn’t correct: safe traits can have unsafe methods, and unsafe traits can exist without any methods at all (as implied by my reference to Send and Sync). You can see this in practice in the following example, which compiles just fine!

trait ASafeTrait { unsafe fn unsafe_method() {} } unsafe AnUnsafeTrait {}

The idea of an unsafe trait is that it has some conditions which you must uphold to safely implement it – again, just as with Send and Sync. In the case of most traits, this will be because some trait method has invariants it needs to hold else it would cause undefined behavior. For another example of this, see the (unstable as of the time of recording) trait std::iter::TrustedLen.

Thanks to Rust language team member @centril for noting this to me after listening when I was recording the show live!

Examples

Borrow-checked code in `unsafe`

let mut f = String::from("foo"); unsafe { let borrowed = &mut f; let borrow_again = &f; println!("{}", borrowed); // This would be unsafe and throw an error: // println!("{}", borrow_again); }

(See it in a playground)

Safely mutating a raw pointer

let f = Box::new(12); let mut g = Box::into_raw(f); g = &mut (g + 10);

(See it in a playground)

Contact

New Rustacean: + Twitter: @newrustacean + Email: hello@newrustacean.com
Chris Krycho + GitHub: chriskrycho + Twitter: @chriskrycho

105 episodios

#Prog Languages #Tech News #Rust #Programming #Software #Chris Krycho #Tech #Podcasting Education #Programming Language