this post was submitted on 12 Jun 2023
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While I have your ear, "who" exactly are the owners in Rust? So far I've come to understand it from the aliasing XOR mutability perspective, so I don't really understand the more common terminology.
When you create an instance of a struct and assign it to a variable or field of another struct, that variable becomes the owner of that value. When you assign it to some other variable or pass it to a function that takes ownership, ownership will move. Otherwise, you will borrow. But there will always only be one owner for each value. That way you know exactly when to free up memory: whenever the owner is dropped.
So then when you say "most operations on data will be done by the owner of that data", do you mean ownership-taking functions? In my head a variable is like a bin, so it's odd to think of it doing any "operations" other than holding.
No, I phrased that poorly. What I meant is that if you have a struct that has some field (it owns that data), your operations on that data will be methods of that struct, and not some other struct that happens to have a reference to that struct. The latter is something people tend to do in OO languages like Java. In Rust, if a function accesses data, you usually "freshly" borrow from the owner of that data and pass it as argument to that function instead of relying on some "hidden" references somewhere in hidden in an object. Borrows will almost always be short-lived.
I don't know if any of this makes sense, I'm sorry for the bad explanation. It might make more sense if you play with Rust yourself.
Alright, thanks! I have every intention of playing around a bit.