rust

问题 The following code involves a very subtle bit of borrow checker dodging. The code itself describes the reasoning. The questions: Is this actually safe? Is this the recommended way to express the unsafe operations performed? Should I use pointers instead? Will the new Polonius borrow checker be able to reason about patterns like this? /// Insert a new data element at a given key. pub fn insert<'a, K: Eq, V>(this: &'a mut Vec<(K, V)>, key: K, val: V) -> &'a mut V { // Safety: As indicated below

问题 The following code involves a very subtle bit of borrow checker dodging. The code itself describes the reasoning. The questions: Is this actually safe? Is this the recommended way to express the unsafe operations performed? Should I use pointers instead? Will the new Polonius borrow checker be able to reason about patterns like this? /// Insert a new data element at a given key. pub fn insert<'a, K: Eq, V>(this: &'a mut Vec<(K, V)>, key: K, val: V) -> &'a mut V { // Safety: As indicated below

问题 I'm working on Project Euler 96 to teach myself Rust. I've written this code to read in the file and convert it into a vector of integers (Playground). let file = File::open(&args[1]).expect("Sudoku file not found"); let reader = BufReader::new(file); let x = reader .lines() .map(|x| x.unwrap()) .filter(|x| !x.starts_with("Grid")) .flat_map(|s| s.chars().collect::<Vec<_>>()) // <-- collect here! .map(|x| x.to_digit(10).unwrap()) .collect::<Vec<_>>(); This all works fine but I'm puzzled why I

问题 I have something similar to this: mod private { // My crate pub struct A; impl A { pub fn new() -> Self { Self } // ... } } fn main() { // External code let obj = private::A::new(); let obj2 = private::A; } Currently, A doesn't need to store any internal state to do what I want it to (it's just being used as a placeholder in an enum), so I made it a zero-sized struct. However, that might change in the future, so I want to prevent code outside this crate from instantiating A without going

问题 I have something similar to this: mod private { // My crate pub struct A; impl A { pub fn new() -> Self { Self } // ... } } fn main() { // External code let obj = private::A::new(); let obj2 = private::A; } Currently, A doesn't need to store any internal state to do what I want it to (it's just being used as a placeholder in an enum), so I made it a zero-sized struct. However, that might change in the future, so I want to prevent code outside this crate from instantiating A without going

问题 Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 10 months ago . Improve this question I'm new to Rust. I try to create a Point struct that implements Eq and Debug , so I did this: use std::fmt; pub struct Point { x: f32, y: f32, } impl Point { pub fn new(x: f32, y: f32) -> Point { Point{ x: x, y: y, } } } impl fmt::Debug for Point { fn fmt(

问题 I am porting a compiler I wrote to Rust. In it, I have an enum Entity which represents things like functions and variables: pub enum Entity<'a> { Variable(VariableEntity), Function(FunctionEntity<'a>) // Room for more later. } I then have a struct Scope which is responsible for holding on to these entities in a hash map, where the key is the name given by the programmer to the entity. (For example, declaring a function named sin would put an Entity into the hash map at the key sin .) pub

问题 I am porting a compiler I wrote to Rust. In it, I have an enum Entity which represents things like functions and variables: pub enum Entity<'a> { Variable(VariableEntity), Function(FunctionEntity<'a>) // Room for more later. } I then have a struct Scope which is responsible for holding on to these entities in a hash map, where the key is the name given by the programmer to the entity. (For example, declaring a function named sin would put an Entity into the hash map at the key sin .) pub

问题 I am writing a command line application in rust for processing audio from a sensor. I would like the user to be able to choose an algorithm or filter to apply from several options. I was hoping to use dynamic dispatch to switch out a struct which implements my filter trait at runtime. However, this is not allowed by the compiler, because one of the trait methods takes a generic parameter. How could I implement this same functionality, without causing any compiler troubles? I know that an easy

问题 I am writing a command line application in rust for processing audio from a sensor. I would like the user to be able to choose an algorithm or filter to apply from several options. I was hoping to use dynamic dispatch to switch out a struct which implements my filter trait at runtime. However, this is not allowed by the compiler, because one of the trait methods takes a generic parameter. How could I implement this same functionality, without causing any compiler troubles? I know that an easy