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451 points birdculture | 1 comments | | HN request time: 0.267s | source
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Animats ◴[] No.43979394[source]
It's like reading "A Discipline of Programming", by Dijkstra. That morality play approach was needed back then, because nobody knew how to think about this stuff.

Most explanations of ownership in Rust are far too wordy. See [1]. The core concepts are mostly there, but hidden under all the examples.

    - Each data object in Rust has exactly one owner.
      - Ownership can be transferred in ways that preserve the one-owner rule.
      - If you need multiple ownership, the real owner has to be a reference-counted cell. 
        Those cells can be cloned (duplicated.)
      - If the owner goes away, so do the things it owns.

    - You can borrow access to a data object using a reference. 
      - There's a big distinction between owning and referencing.
      - References can be passed around and stored, but cannot outlive the object.
        (That would be a "dangling pointer" error).
      - This is strictly enforced at compile time by the borrow checker.
That explains the model. Once that's understood, all the details can be tied back to those rules.

[1] https://doc.rust-lang.org/book/ch04-01-what-is-ownership.htm...

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codeflo ◴[] No.43981587[source]
That's not explaining ownership, that motivating it. Which is fine. The thing that's hard to explain and learn is how to read function signatures involving <'a, 'b>(...) -> &'a [&'b str] or whatever. And how to understand and fix the compiler errors in code calling such a function.
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1. cmrdporcupine ◴[] No.43983434[source]
The good news is that idiomatically written good clean Rust code doesn't need to rely on such borrow signatures very often. That's more when you're leaving the norm and doing something "clever."

I know it throws people off, and the compiler error can be confusing, but actual explicit lifetimes as part of a signature are less common than you'd expect.

To me it's a code smell to see a lot of them.