Recent questions tagged rust

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rust - How to execute cargo test using the nightly channel?

I'm trying to run my tests with nightly Rust using Windows Powershell. I run cargo test in the directory, and I ... or any website I've found. See Question&Answers more detail:os...

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

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789 views

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rust - What's the difference between `<T: Trait>` and `where T: Trait`?

In the docs for the Send trait, I see both impl<T> Send for LinkedList<T> where T: Send, and impl< ... impl declarations for my own trait? 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 - Getting "temporary value dropped while borrowed" when trying to update an Option<&str> in a loop

I'm trying to implement a commonly used pattern - using the result of a previous loop iteration in the next loop ... it's supposed to be done. See Question&Answers more detail:os...

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

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885 views

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rust - How to force a move of a type which implements the Copy trait?

A custom type by default is moved through default assignment. By implementing the Copy trait, I get "shallow ... that that would have worked. 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 does one round a floating point number to a specified number of digits?

How does one round a f64 floating point number in Rust to a specified number of digits? See Question&Answers more detail:os...

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

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727 views

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rust - Generic struct over a generic type without type parameter

Is it possible to do something like this in Rust? trait Foo<T> {} struct A; struct B; struct Bar<T: ... single thread and multi thread usage. 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 difference between `|_| async move {}` and `async move |_| {}`

Let's consider the following examples: main.rs use futures::executor::block_on; use futures::future::{FutureExt, ... (4560ea788 2019-11-04) See Question&Answers more detail:os...

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

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717 views

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rust - What is the prelude?

When talking about imports, the word prelude is used every so often by the rustaceans. What is this prelude they ... it affect my Rust programs? See Question&Answers more detail:os...

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

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762 views

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rust - How do I get an enum as a string?

I have an enum with many values and I'd like to write the name of one of its values to a stream: ... formatting calculations I want to do. See Question&Answers more detail:os...

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

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652 views

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rust - What are examples of types that implement only one of Send and Sync?

Just to get better understanding of the Send and Sync traits, are there examples of types that either: Implement ... and do not implement 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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862 views

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rust - How to print structs and arrays?

Go seems to be able to print structs and arrays directly. struct MyStruct { a: i32, b: i32 } and let arr: [i32; 10] = [1; 10]; See Question&Answers more detail:os...

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

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800 views

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rust - How do I sum a vector using fold?

This Rust tutorial explains the fold() mechanism well, and this example code: let sum = (1..4).fold(0, |sum, ... m using Rust beta, 2015-04-02. See Question&Answers more detail:os...

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

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790 views

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rust - How can I read a single line from stdin?

I'm asking for the equivalent of fgets() in C. let line = ...; println!("You entered: {}", line); I've read ... fgets() or sscanf("%s",...). 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 the PathBuf to String

I have to convert the PathBuf variable to a String to feed my function. My code is like this: let cwd = ... suggestions on how to handle it? See Question&Answers more detail:os...

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

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744 views

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rust - What are Some and None?

I came across some output I don't understand using Vec::get. Here's the code: fn main() { let command = [( ... why .get() returns Some or 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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784 views

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rust - Using map with Vectors

Although vectors are best suited for procedural programming, I would like to use a map function on them. The following ... way to deal with it? See Question&Answers more detail:os...

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

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646 views

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rust - What is typestate?

What does TypeState refer to in respect to language design? I saw it mentioned in some discussions regarding a ... by mozilla called Rust. See Question&Answers more detail:os...

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

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815 views

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rust - How can I statically register structures at compile time?

I'm looking for the right method to statically register structures at compile time. The origin of this ... preferably at compile time. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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799 views

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rust - Compiler asking for lifetime in struct when lifetime is given

I'm trying to write the examples in the book "SFML Game Development" but I'm having a problem with the lifetimes ... if I have given it one? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

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rust - What is the proper way to use the `cfg!` macro to choose between multiple implementations?

I have specified a few features inside Cargo.toml: [features] complex = [] simple = [] When I build my project I ... the cfg! macro in my case? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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745 views

1 answer

rust - Can't implement a trait I don't own for all types that implement a trait I do own

pub trait AllValues { fn all_values() -> Vec<Self> where Self: std::marker::Sized; } use rand:: ... Rand for things that implement AllValues? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

1 answer

rust - How to conditionally deserialize JSON to two different variants of an enum?

Let's say I have JSON data like the following: { "type": "A", "value": [ 1, 2, 3, 4, ... serde deserialization to properly decode these values? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

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rust - Why do I get "conflicting implementations of trait" for f32 which does not implement Ord?

I want a min() method for f32, u32 and i32, so I created a trait Min: trait Min { fn min(v1 ... Ord. Why there are conflicting implementations? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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832 views

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rust - Borrow data out of a mutex "borrowed value does not live long enough"

How can I return an iterator over data within a mutex which itself is contained within a struct. The error the ... link: http://is.gd/voukyN See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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704 views

1 answer

rust - What does it mean that Box is covariant if Box<dyn B> is not a subtype of Box<dyn A> where B: A?

After I read the subtyping chapter of the Nomicon, I couldn't wrap my head around covariance of a type ... only use cases are invariants? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.1k views

1 answer

rust - How to get the byte offset between `&str`

I have two &str pointing to the same string, and I need to know the byte offset between them: fn main() ... is not implemented on raw pointers. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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1.2k views

1 answer

rust - Expected closure, found a different closure

A is a structure which contains a vector of B. A implements the add_b method which adds a B instance to the ... different closures to A's b_vec? See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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916 views

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rust - Cannot borrow `*self` as mutable because `self.history[..]` is also borrowed as immutable

The code is something like the following, in a function that is an implementation for a Context struct, ... for demonstrative purposes only. See Question&Answers more detail:os...

asked Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

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