Ownership, performance, and when cloning is actually the right choice?

[scottmcm]

@Alexanderhiggins

When I try to avoid cloning by passing references everywhere, things often get complicated pretty quickly.

Yes, absolutely.

Here's the simple version that doesn't run into trouble:

Returning strings: `String` vs. `&str`

Here's my Rust 101 rules for this: "&str for parameters; String for return types". This always works, and has no borrowck complications, but is sometimes inefficient. the small tweak to add "If you always need to to_owned/to_string the &str parameter, change it to a String parameter". That's more efficient when your caller happens to already have a String, no less efficient if they don't, and still doesn't require thinking about lifetimes. if you're always returning a substring of on…

You can always change to fancier things later once you're more comfortable, but TBH you usually don't need it.

TL/DR:

@kornel

You're not allowed to use references in structs until you think Rust is easy. They're the evil-hardmode of Rust that will ruin your day.