Recent questions tagged rust

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rust - Cannot use moved BufReader after for loop with bufreader.lines()

I'm trying to read some lines from a file, skipping the first few and printing the rest, but I keep getting ... not implement the `Copy` trait See Question&Answers more detail:os...

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

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rust - How to represent shared mutable state?

I'm trying to learn Rust, but the only thing I do is keep hitting the wall trying to shoehorn familiar (to me) ... in Rust (at least for me). See Question&Answers more detail:os...

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

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rust - How do I pin indirect dependencies of a crate?

My project A depends on library B that depends on library C. Library B sets the dependency version to "* ... sure it will compile successfully. See Question&Answers more detail:os...

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

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rust - How can I override a constant via a compiler option?

Is it possible to define a constant in source code that can be overridden by a compiler flag? That is, ... MAX_DIMENSIONS: usize = 100_000; See Question&Answers more detail:os...

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

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rust - Why does an enum require extra memory size?

My understanding is that enum is like union in C and the system will allocate the largest of the data types in the ... but E2 takes up 16 bytes? See Question&Answers more detail:os...

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

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rust - Why does a lazy-static value claim to not implement a trait that it clearly implements?

With the following code (an attempt to make an HTTP request using the reqwest crate), the compiler says that ... ::IntoUrl` for `SID_URI` See Question&Answers more detail:os...

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

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rust - Sized is not implemented for the type Fn

I want to build a function that splits a list into two: one list that contains the elements of the original ... , but apparently it doesn't. See Question&Answers more detail:os...

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

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rust - What does "missing lifetime specifier" mean when storing a &str in a structure?

I am trying to code an Excel-like data structure: use std::collections::HashMap; struct Excel { columns: ... understand what's going on? See Question&Answers more detail:os...

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

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rust - Why can I iterate over a slice twice, but not a vector?

If I try to iterate over a slice twice, it works fine: let a = &[1, 2, 3]; for i in a { ... example fails. Why does the first example succeed? See Question&Answers more detail:os...

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

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rust - How to read a specific number of bytes from a stream?

I have a struct with a BufStream<T> where T: Read+Write. The BufStream can be a TcpStream and I'd like to read ... there a nice way to do that? See Question&Answers more detail:os...

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

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rust - How do I overcome match arms with incompatible types for structs implementing same trait?

I am attempting to write the cat command to learn Rust, but I can't seem to convert command line arguments into ... File or Stdin as a reader? See Question&Answers more detail:os...

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

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rust - Why "explicit lifetime bound required" for Box<T> in struct?

Editor's note: This code no longer produces the same error after RFC 599 was implemented, but the concepts discussed in ... -13 20:36:02 +0000) See Question&Answers more detail:os...

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

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rust - Is there a way to get the field names of a struct in a macro?

Consider the following example: struct S { a: String, b: String, } I have a macro which is called like ... maybe I'm missing something obvious. See Question&Answers more detail:os...

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

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rust - What is the difference between a constant and a static variable and which should I choose?

I know this from RFC 246: constants declare constant values. These represent a value, not a memory address. This ... Which one should I choose? See Question&Answers more detail:os...

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

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758 views

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rust - How can an operator be overloaded for different RHS types and return values?

Given the following struct: struct Vector3D { x: f32, y: f32, z: f32 } I want to overload its * ... vice versa for the other implementation. 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 - When I can use either Cell or RefCell, which should I choose?

From the std::cell documentation, I see that Cell is "only compatible with types that implement Copy". This means I ... }", cell.count()); } See Question&Answers more detail:os...

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

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rust - How can I read one character from stdin without having to hit enter?

I want to run an executable that blocks on stdin and when a key is pressed that same character is printed immediately ... not simple in C/C++. See Question&Answers more detail:os...

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

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rust - Is there a good way to convert a Vec<T> to an array?

Is there a good way to convert a Vec<T> with size S to an array of type [T; S]? Specifically, I ... copying each element, and returns the array? See Question&Answers more detail:os...

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

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750 views

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rust - What is monomorphisation with context to C++?

Dave Herman's recent talk in Rust said that they borrowed this property from C++. I couldn't ... please explain what monomorphisation means? 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 - Cannot create a generic function that uses a literal zero

I am trying to write a Rust function that is similar to the built-in Range, but I want something that will return ... `T` found type `{integer}` See Question&Answers more detail:os...

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

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656 views

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rust - Is there a way to perform an index access to an instance of a struct?

Is there a way to perform an index access to an instance of a struct like this: struct MyStruct { // ... } impl ... ; // This is what I need } See Question&Answers more detail:os...

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

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851 views

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rust - How to end a borrow in a match or if let expression?

I am using a HashMap to store an enum. I'd like to get a value from the HashMap and if the value is a ... that I can get a new mutable borrow? 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

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rust - HashMap borrow issue when trying to implement find or insert

I tried to implement own analogue of find_or_insert method that looks like this: use std::collections::HashMap; ... work around such situations? See Question&Answers more detail:os...

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

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rust - What expressions are allowed as the array length N in [_; N]?

Please consider the following minimal example in Rust: const FOOBAR: usize = 3; trait Foo { const BAR: usize; ... compile-time constant size, N. See Question&Answers more detail:os...

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

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997 views

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rust - Generics Error: expected type parameter, found struct

I started a new project, where I want to be as modular as possible, by that I mean that I would like to be ... could do to to make it 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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931 views

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rust - Can I have a static borrowed reference to a trait object?

Is there a way for me to obtain a static borrowed reference to a struct's implementation of a trait: trait ... invoke f passing in instance2? } See Question&Answers more detail:os...

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

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645 views

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rust - Multiple return types from a method

I am trying to write a simple TV-episode file renamer in Rust. A filename is parsed, and might be one of ... a good way to structure 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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772 views

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rust - Is there a way to use existing structs as enum variants?

I'm using an enum for polymorphism, similar to the following: enum MyType { Variant1 { a: i32, b: i32 }, ... way to accomplish a similar thing. See Question&Answers more detail:os...

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

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