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460 points birdculture | 2 comments | | HN request time: 0.419s | 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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1. geokon ◴[] No.44028129[source]
I don't do Rust, but I feel there must be more to it that's missing in your description b/c what you wrote sounds exactly like a C++ smart pointer?

With the exception of the last point (which I can't imagine tacking on in C++)

Maybe I'm missing some subtle point?

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2. steveklabnik ◴[] No.44030638[source]
They're very similar at this level of abstraction, the final one is the biggest point.