Recent questions tagged Rust

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rust - Generating unique IDs for types at compile time

I want to generate a unique id for every type at compile time. Is this possible in Rust? So far, I have ... <TBase>::m_nextTypeId = 0; } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Unable to borrow an iterator as mutable more than once at a time

I'm writing a simple tokenizer in Rust but I'm having trouble. I've simplified the code a bit for the sake of ... ? It seems a little hack-ish. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Returning a RWLockReadGuard independently from a method

I have an object of type Arc<RwLock<SessionData>> And I have a method that is supposed to take some kind of ... to the provider of the value. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Kill child process while waiting for it

I want to execute another process and normally want to wait until it has finished. Lets say we spawn and wait ... know if there's another way. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - What is the inferred type of a vector of closures?

I tried to create vector of closures: fn main() { let mut vec = Vec::new(); vec.push(Box::new(|| 10)); ... type of vec and why is it that way? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Is it safe to `Send` struct containing `Rc` if strong_count is 1 and weak_count is 0?

I have a struct that is not Send because it contains Rc. Lets say that Arc has too big overhead, so I want ... for the MyStruct to not be Send. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - How to convert a boxed trait into a trait reference?

I have the following code that tries to take a reference to a trait object from a boxed trait: trait T {} ... properly borrow &T from Box<T>? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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984 views

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rust - Why can't I use a function returning a compile-time constant as a constant?

let arr0 = [0u8; 15]; let arr1 = [0u8; arr0.len()]; // this fails I think the compiler should be able to ... 2015-03-21) (built 2015-03-22) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - What's the idiomatic way to copy from a primitive type reference by value?

Consider the following snippet: fn example(current_items: Vec<usize>, mut all_items: Vec<i32>) { for i in ... primitive type reference by value? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - How can I get impl Trait to use the appropriate lifetime for a mutable reference to a value with another lifetime in it?

I have a struct with a lifetime: struct HasLifetime<'a>( /* ... */ ); There is there is an ... bar_to_foo with impl Trait? Playground link See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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833 views

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rust - How do I use a crate from another crate without explicitly defining a new dependency in my project?

I want to use the dijkstra function from the pathfinding crate: pub fn dijkstra<N, C, FN, IN, FS>( ... ? use pathfinding::num_traits::Zero; See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Implementing mean function for generic types

I'm trying to write a function to return the mean of a Vector. I want it to work with generic types but I' ... . How should I go about this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Impl trait with generic associated type in return position causes lifetime error

I need to store a fn(I) -> O (where I & O can be references) in a 'static struct. O needs ... ` dropped here while still borrowed } playground See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Why can a &str not be passed to a function accepting a &dyn Display trait object?

I'm reading a Rust book and I am confused by this example: use std::fmt::Display; fn main() { test(" ... this fail and the second call work? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - How to advance through data from the std::io::Read trait when Seek isn't implemented?

What's the best way to read from a type implementing the std::io::Read trait when the contents of the ... a convenient way to achieve this? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - How do I write a function that takes both owned and non-owned string collections?

I'm having trouble writing a function that takes a collection of strings as parameter. My function looks ... strings and string references? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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817 views

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rust - What are the differences between specifying lifetime parameters on an impl or on a method?

In Rust 1.3.0, the Deref trait has the following signature in the documentation: pub trait Deref { type Target: ... . What am I missing here? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Is it possible to convert Option<Result<T, E>> to a Result<Option<T>, E> without using match?

My first thought is to map the Option, but I can't use try! from inside of the closure. The match statement looks ... ?), None => None }) } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - When should I add mut to closures?

fn main() { let mut a = String::from("a"); let closure = || { a.push_str("b"); }; closure(); } This ... won't it be borrowed when I return a? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

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rust - How do I conditionally check if an enum is one variant or another?

I have an enum with two variants: enum DatabaseType { Memory, RocksDB, } What do I need in order to make a conditional if ... //.......... } } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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984 views

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rust - Why do I get the error "the trait `Foo` is not implemented for `&mut T`" even though T implements the trait?

I have this source: pub fn draw<G, C>(&self, font: &mut C, draw_state: &DrawState, transform: Matrix2d, g: ... Graphics<Texture = C::Texture>, See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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883 views

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rust - How to map a parametrized enum from a generic type to another?

If I have a type like MyEnum<T>, how can I map it in cases where not every variant is parameterized? For ... MyEnum<String> = other_cases; o } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - Expected bound lifetime parameter, found concrete lifetime

I can't figure out the lifetime parameters for this code. Everything I try usually results in a compiler error: ... running"); } Rust Playground See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.3k views

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rust - How to convert Unix time / time since the epoch to standard date and time?

I'm using the chrono crate; after some digging I discovered the DateTime type has a function timestamp() which could ... to convert it back? } See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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rust - How do I print an integer in binary with leading zeros?

I'm doing some bit twiddling and I'd like to print all the bits in my u16. let flags = ... make it print flags: 0b0000000000101100? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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rust - How to implement Eq and Hash for my own structs to use them as a HashMap key?

I have two structs, A and B, and I want to use a HashMap<A, B>. I have a piece of code like this ... Why is there no implementation in the docs? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

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rust - Remove single trailing newline from String without cloning

I have written a function to prompt for input and return the result. In this version the returned string includes a ... the ' ' with ''). See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.4k views

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rust - How do I write a formatted string to a file?

I want to write output of my function to a file. I expected that write_fmt is what I require: use std ... t much available in the documentation. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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