Recent questions tagged rust

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rust - How to bind multiple fields of a boxed struct without getting "use moved value" error?

I'm trying to code a generic recursive data structure. As it turns out, I can't as I'm hitting a wall when I ... reference? I'm using Rust 1.1. 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 - Maximum size of an array in 32 bits?

According to the Rust Reference: The isize type is a signed integer type with the same number of bits as the platform' ... 2GB in Rust? Or not? 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 possible to have multiple mutable references with static lifetime in same scope

Why can I have multiple mutable references to a static type in the same scope? My code: static mut CURSOR: ... got from get_b() individually? 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 access a variable outside of an `if let` expression?

I'm trying to access command line arguments. If the argument exists, do something, if not, do nothing. I have this ... what I'm trying 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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rust - Why does an if without an else always result in () as the value?

From this tutorial: An if without an else always results in () as the value. Why does Rust impose this restriction and doesn ... x == 5 { 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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rust - What is the correct type to use for an array index?

This code works, but I want to explicitly declare the type of the index range max. However uX or iX, where X = 8, 16 ... , arr2[ii][jj]); } } } 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 use a custom comparator function with BTreeSet?

In C++, it is possible to customize the code std::set uses to sort its arguments. By default it ... comparators with Rust's container types? 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 - Can tests be built in release mode using Cargo?

I'm using cargo build --release to build my project in release configuration and cargo test to build and run my ... this be done using cargo? 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 do changes to a const variable not persist between usages?

I am trying to create a struct to manipulate file storage, but after I change the value it can not be ... the variable continues to be 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 - What is the right smart pointer to have multiple strong references and allow mutability?

I want to have a structure on the heap with two references; one for me and another from a closure. Note ... so everything will work as expected. 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 - Solutions to performance issues caused by large variant size of enum

I am trying to build a tree-like data structure using the Node representation: use std::cmp::Ordering; use ... having the overhead of enums? 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 - variable does not live long enough when storing a csv::DecodedRecords iterator

I'm trying to create an iterator trait that provides a specific type of resource, so I can implement multiple source ... what am I doing wrong? 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 - Creating a struct with a generic trait for field. Expected struct<trait> found struct<type that implements said trait>

I'm trying to create a struct that has a BufWriter that uses the Write trait, so that this struct could ... should be possible to do somehow. 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 use functions from one file among multiple files?

I'm trying to use the functions from one file with multiple other files. When I try adding 'mod somefile' to the ... zzz.rs, src/bbb/zzz.rs). 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 an idiomatic way to keep references to elements of an ever-growing container?

I'm trying to write a container for objects of type T which provides access to references &T to the stored ... example (without copying x)? 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 way to iterate over a mutable tree to get a random node?

I am trying to update a node of a tree structure. A node which is to be updated is selected randomly. To sample a node ... !("{:?}", tree); } 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 - Can a build script take arguments?

I was going through the build script documentation and was wondering if I can pass any argument to the script ... arguments from command line? 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 allocate a Vec<u8> that is aligned to the size of the cache line?

I need to allocate a buffer for reading from a File, but this buffer must be aligned to the size of ... issues (like launching an instruction). 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 it is not possible to use the ... syntax in expressions?

I'm trying understand the ... syntax. Consider the following program: fn how_many(x: i32) -> &'static ... not possible to use within println. 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 - Lifetimes when Deserializing JSON within a FromForm

I'm having trouble understanding the relationship between the lifetimes on this code. Basically, I have a ... the deserialized value properly? 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 pass modified string parameters?

I'm on chapter 12 of The Rust Programming Language, where a case insensitive line search is implemented. It doesn't make sense ... ^^^^^^^^^^^^^ 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 - Possible to combine assignment and comparison in an expression?

In C, it's common to assign and compare in a single expression: n = n_init; do { func(n); } while ... some better/different way to express 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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rust - Generic implementation depending on traits

When defining a generic struct, is there a way in Rust to use different implementation of a method according to which ... }; s.print_me(); } 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 I can still access a vector's element after taking ownership of it without using reference?

fn main() { let number_list = vec![1, 2, 3, 4, 5]; let n = number_list[0]; let r = ... and a non-reference except taking the reference? 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 a reference variable accessed via auto-deref moved?

I thought I got the idea of move semantics until this code. fn main() { let v = Data { body: vec![10, 40 ... deref feature, so why is it a move? 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 should I restructure my graph code to avoid an "Cannot borrow variable as mutable more than once at a time" error?

I have a simple graph that successfully compiles: use std::collections::HashMap; type Key = usize; type ... should I restructure this code? 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 an Iterator-like trait which returns references that must fall out of scope before the next access?

This would make it possible to safely iterate over the same element twice, or to hold some state for the ... loop notation. Is that possible? 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 tuple of references to a reference of a tuple?

I'd like to convert a tuple of references (which are all references to members of the same struct) to a reference ... given a is of type &Foo. See Question&Answers more detail:os...

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

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