Recent questions tagged rust

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rust - Implementing Ord for a type is awkward?

I have a newtype and I want to implement Ord: use std::cmp::{Ord, Ordering}; struct MyType(isize); impl Ord for ... Rust? I hope not this 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 there a more concise way to format .expect() message?

I currently have to use this to format a .expect() message: fn main() { let x: Option<&str> = None; x. ... ; } Is there a less verbose 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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1.1k views

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rust - std::ops::Add or core::ops::Add?

These two traits (std::ops::Add, core::ops::Add) provide the same functionality, and they both use the same ... opposed to one, of them exist? 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 - Why is type conversion from u64 to usize allowed using `as` but not `From`?

The first conversion using 'as' compiles, but the second one using the 'From' trait does not: fn main() { ... as' should also fail to compile? See Question&Answers more detail:os...

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

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872 views

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rust - Can you disable constructor syntax for a type?

Say I define my own type in a Rust library, like so: struct Date { year: u16, month: u8, day: u8 } ... created; feel free to comment on that.) See Question&Answers more detail:os...

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

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840 views

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rust - Why are borrows of struct members allowed in &mut self, but not of self to immutable methods?

If I have a struct that encapsulates two members, and updates one based on the other, that's fine as long ... the compiler saving me from 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 - How do I call a function that requires a 'static lifetime with a variable created in main?

I've got a struct defined that has a function which defines a static lifetime: impl MyStruct { pub fn doSomething( ... a 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 - Recovering from `panic!` in another thread

I know that in Rust there is no try/catch, and you can't throw a rolling save from the thread that is ... error is of type Any. Thanks! 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 is it useful to use PhantomData to inform the compiler that a struct owns a generic if I already implement Drop?

In the Rustonomicon's guide to PhantomData, there is a part about what happens if a Vec-like struct has *const ... that my struct owns some Ts? See Question&Answers more detail:os...

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

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1.5k views

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rust - How do I implement Ord for a struct?

I've seen a question similar to this one, but no one that tells me exactly how to implement Ord for a struct. ... are not a member of Ord. 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 can I remove duplicates from a vector of custom structs?

I'm trying to remove duplicates in the below example: struct User { reference: String, email: String, } fn main ... I have to do something else? See Question&Answers more detail:os...

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

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932 views

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rust - How can I get Serde to allocate strings from an arena during deserialization?

I have a struct with string fields. I'd like to control how the memory for the strings is allocated. In ... with the arena lifetime, right? See Question&Answers more detail:os...

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

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884 views

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rust - How can I box the contents of an iterator of a type that implements a trait?

I'm taking an iterator of some type that must implement the trait A, and trying to convert it into a Vec of ... than whatever type they may be? See Question&Answers more detail:os...

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

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954 views

1 answer

rust - Is there a way to distinguish between different `Rc`s of the same value?

Here's an example: use std::rc::Rc; #[derive(PartialEq, Eq)] struct MyId; pub fn main() { let rc_a_0 ... between the rc_a_* and rc_b_* pointers? 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

1 answer

rust - How do I create two new mutable slices from one slice?

I would like to take a mutable slice and copy the contents into two new mutable slices. Each slice being one half of ... ("{:?}", my_list); } See Question&Answers more detail:os...

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

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875 views

1 answer

rust - What is the stabilization process?

What is the stabilization process? Reading the release notes I see a lot of different standard library APIs and ... does an API become stable? See Question&Answers more detail:os...

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

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832 views

1 answer

rust - How can I modify a slice that is a function parameter?

Parameters can be passed to functions and modified: fn set_42(int: &mut i32) { *int += 42; } fn main() { ... it becomes a smaller "sub-slice". See Question&Answers more detail:os...

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

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876 views

1 answer

rust - Can I prevent cargo from rebuilding libraries with every new project?

Suppose I execute cargo new one --bin and cargo new two --bin then add the same dependency to ... compiled libraries to avoid recompilation? See Question&Answers more detail:os...

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

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905 views

1 answer

rust - Why does this mutable borrow live beyond its scope?

I've encountered a confusing error about the use of a mutable and immutable borrow at the same time, after I expect ... and how I can avoid it. See Question&Answers more detail:os...

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

0 votes

1.0k views

1 answer

rust - How to clone an array with length bigger than 32?

A fixed-length array of a native type (or of a type that implements the Copy trait) can be cloned in Rust up ... array of length, say, 33? See Question&Answers more detail:os...

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

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895 views

1 answer

rust - Dereferencing Box<T> gives back value instead of reference

I can't seem to figure out why: let a = Box::new(5i32); let _:() = *a; tells me that the assigned type ... ::deref(&a); I get the expected &i32. See Question&Answers more detail:os...

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

0 votes

1.1k views

1 answer

rust - What does "cannot borrow as immutable because it is also borrowed as mutable" mean in an nested array index?

What does the error mean in this case: fn main() { let mut v: Vec<usize> = vec![1, 2, 3, 4, 5 ... equivalent, but this obviously isn't the case. 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

1 answer

rust - Built in *safe* way to move out of Vec<T>?

I've been looking over the documentation, and so far I haven't seen a built in function to safely move an item ... index: usize) -> Option<T>? See Question&Answers more detail:os...

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

0 votes

1.1k views

1 answer

rust - Can I prevent cargo from rebuilding libraries with every new project?

Suppose I execute cargo new one --bin and cargo new two --bin then add the same dependency to ... compiled libraries to avoid recompilation? See Question&Answers more detail:os...

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

0 votes

925 views

1 answer

rust - Why does this mutable borrow live beyond its scope?

I've encountered a confusing error about the use of a mutable and immutable borrow at the same time, after I expect ... and how I can avoid it. See Question&Answers more detail:os...

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

0 votes

1.1k views

1 answer

rust - How to clone an array with length bigger than 32?

A fixed-length array of a native type (or of a type that implements the Copy trait) can be cloned in Rust up ... array of length, say, 33? See Question&Answers more detail:os...

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

0 votes

820 views

1 answer

rust - Dereferencing Box<T> gives back value instead of reference

I can't seem to figure out why: let a = Box::new(5i32); let _:() = *a; tells me that the assigned type ... ::deref(&a); I get the expected &i32. See Question&Answers more detail:os...

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

0 votes

1.5k views

1 answer

rust - What does "cannot borrow as immutable because it is also borrowed as mutable" mean in an nested array index?

What does the error mean in this case: fn main() { let mut v: Vec<usize> = vec![1, 2, 3, 4, 5 ... equivalent, but this obviously isn't the case. See Question&Answers more detail:os...

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

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