borrowing

问题 This question and code are adapted from Why does creating a mutable reference to a dereferenced mutable reference work?. The answers there explained re-borrowing but not the reasons for the conventions around it. The two calls to test below seem equivalent, why does only the first one work? fn main() { let mut string = String::new(); let ref_string = &mut string; // Compiles test(&mut *ref_string); // Doesn't compile test(&mut string); } fn test(s: &mut String) { s.push('t'); } 回答1: You are

问题 This question and code are adapted from Why does creating a mutable reference to a dereferenced mutable reference work?. The answers there explained re-borrowing but not the reasons for the conventions around it. The two calls to test below seem equivalent, why does only the first one work? fn main() { let mut string = String::new(); let ref_string = &mut string; // Compiles test(&mut *ref_string); // Doesn't compile test(&mut string); } fn test(s: &mut String) { s.push('t'); } 回答1: You are

问题 I'm getting an error when trying to use a closure that does exactly the same as the print function below (in ln.9) The error is the usual borrowed value does not live long enough . I've tried to replicate this in the playground but I can't. I'm certain that this is mainly because I don't really understand what's going on here so any help would be really appreciated. What I can't understand is what is the difference between calling the print function and calling the check closure. They have

问题 I have a struct: pub struct CommunityContents { pub friends: RefCell<HashMap<FriendID, FriendData>>, pub index: RefCell<HashMap<u64, BTreeMap<FriendID, FriendData>>>, pub authenticated: bool, pub age: u64, pub height: u64, } Which is protected with a RwLock with a parent struct: pub struct Community { pub community_contents: RwLock<CommunityContents>, } pub struct FriendData { pointer: Rc<Data>, } pub struct Data { pub key: Key, pub friend_ids: Vec<FriendID>, } I want to be able to modify the

问题 Why can't I push to this vector during inspect and do contains on it during skip_while ? I've implemented my own iterator for my own struct Chain like this: struct Chain { n: u32, } impl Chain { fn new(start: u32) -> Chain { Chain { n: start } } } impl Iterator for Chain { type Item = u32; fn next(&mut self) -> Option<u32> { self.n = digit_factorial_sum(self.n); Some(self.n) } } Now what I'd like to do it take while the iterator is producing unique values. So I'm inspect -ing the chain and

问题 I have a struct like this: #[derive(Serialize, Deserialize)] struct Thing { pub small_header: Header, pub big_body: Body, } I want to serialize this Thing to send over the network. I already have a Body available but I can't move it (imagine I am doing something with it, and every now and then I receive a command to temporarily stop what I'm doing and send over whatever data I have now) and I can't copy it (it's too big, possibly hundreds of megabytes). So I'd like Serde to just borrow the

问题 I am studying Rust by Example and running code from the "Alias" page: struct Point { x: i32, y: i32, z: i32, } fn main() { let mut point = Point { x: 0, y: 0, z: 0 }; { let borrowed_point = &point; let another_borrow = &point; // Data can be accessed via the references and the original owner println!( "Point has coordinates: ({}, {}, {})", borrowed_point.x, another_borrow.y, point.z ); // Error! Can't borrow point as mutable because it's currently // borrowed as immutable. let mutable_borrow

问题 I am studying Rust by Example and running code from the "Alias" page: struct Point { x: i32, y: i32, z: i32, } fn main() { let mut point = Point { x: 0, y: 0, z: 0 }; { let borrowed_point = &point; let another_borrow = &point; // Data can be accessed via the references and the original owner println!( "Point has coordinates: ({}, {}, {})", borrowed_point.x, another_borrow.y, point.z ); // Error! Can't borrow point as mutable because it's currently // borrowed as immutable. let mutable_borrow

问题 I am studying Rust by Example and running code from the "Alias" page: struct Point { x: i32, y: i32, z: i32, } fn main() { let mut point = Point { x: 0, y: 0, z: 0 }; { let borrowed_point = &point; let another_borrow = &point; // Data can be accessed via the references and the original owner println!( "Point has coordinates: ({}, {}, {})", borrowed_point.x, another_borrow.y, point.z ); // Error! Can't borrow point as mutable because it's currently // borrowed as immutable. let mutable_borrow

问题 I am studying Rust by Example and running code from the "Alias" page: struct Point { x: i32, y: i32, z: i32, } fn main() { let mut point = Point { x: 0, y: 0, z: 0 }; { let borrowed_point = &point; let another_borrow = &point; // Data can be accessed via the references and the original owner println!( "Point has coordinates: ({}, {}, {})", borrowed_point.x, another_borrow.y, point.z ); // Error! Can't borrow point as mutable because it's currently // borrowed as immutable. let mutable_borrow