Move out of what exactly?

help
#1

What does this mean?

cannot move out of input because it is borrowed

What does something move out of input? I don't think the language works here.

I read the chapter on borrowing in the book and I found it absurdly terse for one of the most complicated parts of the language. Now I'm trying to iterate in a nested loop and am getting this.

#2

It means you are using input in some manner that destroys it, or gives exclusive ownership of it away to someone else.

#3

I get that the first iteration 'destroys' it. Destroy there means: "makes it unavailable in the local scope"?

But who or what moved into input and why is it trying to move out?

I get moving in and out of scope, but this is a variable.

#4

To know this, we'd need to see the code that fails to compile. You could share it via https://play.rust-lang.org/

#5

It sounds like you should show the particular code in question. It depends on the situation, e.g. if you call the .into_iter method on a Vec, that destroys it because into_iter takes self rather than &self or &mut self.

#6

In Rust we say that a variable “owns” its value. “Moving” a value means transferring it from one owner to another. We say that it moves out of the original variable and into some other location.

let foo = input; // moves a value out of `input` and into `foo`

or passing it to a function by value:

f(input); // moves a value out of `input` and into a parameter of `f`

or calling a method that takes its self argument by value:

// moves a value out of `input` and into the `self` parameter of `consume`
input.consume();
1 Like
#7

I guess I'm implicitly calling into_iter on an iterator (not a Vec in this case) if I'm running a for loop?

But "destroy"? Nothing is destroyed, it is moved, so it's unavailable in the current scope, right? I don't get this "destroy" word.

#8

I think I understand the concepts but I just don't get the language, especially the "move out of".

Who's moving out of what?

#9

The value is moving out of one place (variable) and into another.

#10

Aha……… that makes sense.

#11

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