Recent questions tagged Rust

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rust - How can I deserialize JSON with a top-level array using Serde?

I have a some JSON data that is returned from a web service. The JSON is a top-level array: [ { " ... Serde not deserialize top level-arrays? See Question&Answers more detail:os...

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

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1.0k views

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rust - Show u8 slice in hex representation

I need to convert &[u8] to a hex representation. For example [ A9, 45, FF, 00 ... ]. The trait std:: ... is the most canonical way to do this? See Question&Answers more detail:os...

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

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775 views

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rust - Can you clone a closure?

A FnMut closure cannot be cloned, for obvious reasons, but a Fn closure has an immutable scope; is there some way to ... 't clone a &Fn<...>. See Question&Answers more detail:os...

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

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754 views

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rust - Why does printing a pointer print the same thing as printing the dereferenced pointer?

From the Rust guide: To dereference (get the value being referred to rather than the reference itself) y, we use ... or did I miss something? See Question&Answers more detail:os...

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

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770 views

1 answer

rust - How do I use floating point number literals when using generic types?

Regular float literals do not work: extern crate num_traits; use num_traits::float::Float; fn scale_float<T: Float>(x ... ` found type `{float}` See Question&Answers more detail:os...

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

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587 views

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rust - Trait implementation for both a trait object and for direct implementors of the trait

I have a struct that mostly encapsulates a vector: struct Group<S> { elements: Vec<S> } I also have a simple ... Solid>> isn't a great option. See Question&Answers more detail:os...

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

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794 views

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rust - Matching a generic parameter to an associated type in an impl

I have a trait with an associated type and a generic struct:: trait Generator { type Foo; fn generate(&self) ... a where clause that matches it. See Question&Answers more detail:os...

asked Oct 17, 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 syntax: `instance.method::<SomeThing>()`?

I read the below syntax from byteorder: rdr.read_u16::<BigEndian>() I can't find any documentation which ... instance.method::<SomeThing>() See Question&Answers more detail:os...

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

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767 views

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rust - How do I specify lifetime parameters in an associated type?

I have this trait and simple structure: use std::path::{Path, PathBuf}; trait Foo { type Item: AsRef<Path ... to make this work? Rust playground See Question&Answers more detail:os...

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

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647 views

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rust - How do I invoke a system command and capture its output?

Is there a way to invoke a system command, like ls or fuser in Rust? How about capturing its output? See Question&Answers more detail:os...

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

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993 views

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rust - How to use a local unpublished crate?

I've made a library: cargo new my_lib and I want to use that library in a different program: cargo new my_program - ... version of Rust (1.3). See Question&Answers more detail:os...

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

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748 views

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rust - What is the difference between `e1` and `&e2` when used as the for-loop variable?

The compiler says that e1: &i32 and e2: i32. Having read the docs for slice::Iter and the book chapter on loops, I'm ... ", e2); // case 2 } } See Question&Answers more detail:os...

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

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955 views

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rust - What does "mismatched types: expected `()`" mean when using an if expression?

I tried to implement fizzbuzz in Rust and failed with some arcane error: fn main() { let mut i = 1; while i ... do I avoid them in the future? See Question&Answers more detail:os...

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

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681 views

1 answer

rust - Can I avoid eager ambiguity resolution for trait implementations with generics?

Consider the following Rust code [playground]: use std::collections::HashMap; use std::hash::Hash; trait Foo ... possible to have this behavior? See Question&Answers more detail:os...

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

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585 views

1 answer

rust - Why does compilation not fail when a member of a moved value is assigned to?

I am working through examples in Rust by Example. #[derive(Debug)] struct Point { x: f64, y: f64, } ... the assignment on the previous line? See Question&Answers more detail:os...

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

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828 views

1 answer

rust - Why can't I reuse a &mut reference after passing it to a function that accepts a generic type?

Why doesn't this code compile: fn use_cursor(cursor: &mut io::Cursor<&mut Vec<u8>>) { // do some ... 't understand about the borrow-checker? See Question&Answers more detail:os...

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

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983 views

1 answer

rust - Why does passing a closure to function which accepts a function pointer not work?

In the second edition of The Rust Programming Language (emphasis mine): Function pointers implement all three of the ... does this not work? 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

1 answer

rust - Is it possible to implement methods on type aliases?

Consider the following implementation: pub struct BST { root: Link, } type Link = Option<Box<Node>>; struct Node ... my Link typedef in Rust? See Question&Answers more detail:os...

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

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643 views

1 answer

rust - Using generic trait methods like .into() when type inference is impossible

I'm hoping to be able to use .into() to convert a value in a context where type inference is impossible. This ... Is there a trick I am missing? See Question&Answers more detail:os...

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

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620 views

1 answer

rust - What is the right way to allocate data to pass to an FFI call?

After discussing/learning about the correct way to call a FFI of the Windows-API from Rust, I played with it a little ... "0.2" widestring = "*" See Question&Answers more detail:os...

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

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675 views

1 answer

rust - Why is the bound `T: 'a` required in order to store a reference `&'a T`?

Given this code: struct RefWrapper<'a, T> { r: &'a T, } ... the compiler complains: error: ... introducing the syntax Another maybe related RFC See Question&Answers more detail:os...

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

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720 views

1 answer

rust - Can I use the "null pointer optimization" for my own non-pointer types?

When you have an Option<&T>, the compiler knows that NULL is never a possible value for &T, and encodes the ... as None. Is this possible? 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 iterate over and filter an array?

I'm trying to write a program that involves filtering and folding over arrays. I've been using The Rust ... with the array behaves differently. See Question&Answers more detail:os...

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

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642 views

1 answer

rust - How to model complex recursive data structures (graphs)?

I am very interested in Rust and am now starting my first non-trivial project in the language. I am still ... right direction. Thanks a lot. 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 - How to allow optional trailing commas in macros?

Here's a synthetic example of what I want: macro_rules! define_enum { ($Name:ident { $($Variant:ident),* }) => { pub ... !(Foo { A, B, }); See Question&Answers more detail:os...

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

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729 views

1 answer

rust - How to swap two variables?

What is the closest equivalent Rust code to this Python code? a, b = 1, 2 a, b = b, a + b I am trying ... , fib = fib, fib + fibPrev return fib See Question&Answers more detail:os...

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

0 votes

621 views

1 answer

rust - What is the syntax to match on a reference to an enum?

It seems like every introductory document for Rust's enum types explains how to match on an enum object that you ... a reference to an enum? See Question&Answers more detail:os...

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

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800 views

1 answer

rust - How to implement a custom 'fmt::Debug' trait?

I presume you do something like this: extern crate uuid; use uuid::Uuid; use std::fmt::Formatter; use std::fmt:: ... it. What am I doing wrong? See Question&Answers more detail:os...

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

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