Recent questions tagged Rust

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rust - Is there a list of all cfg features?

Rust has the ability to check configuration at build time with, e.g., #[cfg(target_os = "linux")] or ... list of standard attributes anywhere?. 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 get the current time in milliseconds?

How can I get the current time in milliseconds like I can in Java? System.currentTimeMillis() 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 iterate over a range with a custom step?

How can I iterate over a range in Rust with a step other than 1? I'm coming from a C++ background so ... step. How can I accomplish 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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rust - Can I force the use of my dependencies' Cargo.lock when resolving package versions?

The Cargo FAQ states that Cargo.lock is not used for libraries, instead using dependency version ranges found ... modifying the package myself. 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 apply a macro attribute to a function defined in a separate module?

I'm interested in using wasm-bindgen via rust-webpack-template to compile Rust code to WebAssembly. However, I ... to code defined elsewhere? See Question&Answers more detail:os...

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

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596 views

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rust - Is the resource of a shadowed variable binding freed immediately?

According to the Rust book, "when a binding goes out of scope, the resource that they're bound to are freed". Does ... More stuff } // Or here? 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 clone a closure, so that their types are the same?

I have a struct which looks something like this: pub struct MyStruct<F> where F: Fn(usize) -> f64, ... than that of mystruct.mapper. 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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rust - Is it possible to use a HashSet as the key to a HashMap?

I would like to use a HashSet as the key to a HashMap. Is this possible? use std::collections::{HashMap, HashSet}; ... ::HashMap<K, V>>::new` 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 cited problem with using generic type parameters in trait objects?

I am reading Object Safety Is Required for Trait Objects and I don't understand the problem with generic type ... paragraph I'd be grateful. 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 iterate on an Option<Vec<_>>?

I am trying to iterate on on Option<Vec<>>. #[derive(Debug)] pub struct Person { pub name: Option<String> ... is the link to the 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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782 views

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rust - What makes `impl Trait` as an argument "universal" and as a return value "existential"?

I was reading the RFC on "expanding" impl Trait when I came upon the following: By contrast, a programmer ... and the second one existential? 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 guarantee that a type that doesn't implement Sync can actually be safely shared between threads?

I have code that creates a RefCell and then wants to pass a reference to that RefCell to a single thread: use ... than happy to be told why. 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 using Option::map to Box::new a trait object not work?

trait FooTrait {} struct FooStruct; impl FooTrait for FooStruct {} fn main() { let maybe_struct: Option<dyn FooStruct> ... obvious, or... huh? See Question&Answers more detail:os...

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

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960 views

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rust - How can I deserialize an enum when the case doesn't match?

I have a JSON structure that looks like this: { "type": "suite", "event": "started", "test_count": 1 } I ... like to be able to use PascalCase. See Question&Answers more detail:os...

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

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667 views

1 answer

rust - Cannot pass self as callback parameter due to double borrowing

I'm trying to call closure that was saved inside a struct but I'd also like to pass the struct as an ... will avoid this double borrow attempt? See Question&Answers more detail:os...

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

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779 views

1 answer

rust - Mutating an item inside of nested loops

I'm trying to write a program to evenly (or as close to possible) distribute points about the surface of a ... m now absolutely stuck for ideas. See Question&Answers more detail:os...

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

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657 views

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rust - Why does the compiler not complain that an iterator moved to a for loop is immutable?

I am reading the second edition of the Rust Book and I found the following sample in the iterators section ... an immutable variable to mutable? See Question&Answers more detail:os...

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

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661 views

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rust - How do I add references to a container when the borrowed values are created after the container?

For reasons related to code organization, I need the compiler to accept the following (simplified) code: fn f() ... compile this in safe 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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654 views

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rust - Why doesn't the lifetime of a mutable borrow end when the function call is complete?

I'm writing a bot for halite.io, and am having issues understanding some of the effects of borrowing. ... be available to borrow afterwards? See Question&Answers more detail:os...

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

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2.2k views

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rust - How can I solve "use of moved value" and "which does not implement the `Copy` trait"?

I'm trying to read the values from a vector and use the values as indexes to perform an addition: fn main( ... 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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658 views

1 answer

rust - How can I approximate method overloading?

I am modeling an API where method overloading would be a good fit. My na?ve attempt failed: // fn attempt_1( ... ? Is there a cleaner way? See Question&Answers more detail:os...

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

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650 views

1 answer

rust - Is there a way to create a data type that only accepts a range of values?

I have a function that takes an argument of type u16. Is there an elegant way to define a custom data type ... has values between 0 and 100? 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

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rust - Downcast traits inside Rc for AST manipulation

I'm trying to manipulate ASTs in Rust. There will be lots of manipulations, and I want my trees to be ... should I do it completely 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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847 views

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rust - Is there any way to restrict a generic type to one of several types?

I'm trying to create a generic struct which uses an "integer type" for references into an array. For performance ... any way to express 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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985 views

1 answer

rust - How can I find a subsequence in a &[u8] slice?

I have a &[u8] slice over a binary buffer. I need to parse it, but a lot of the methods that I would like ... so I don't think split will 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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994 views

1 answer

rust - Unable to find symbols from extern crates included with `use`

I'm trying to use some Rust libraries from crates on Github. This is the first time I've tried to do this. The ... 2014-12-21 20:43:45 +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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716 views

1 answer

rust - How can callbacks with captured mutable variables be treated like normal mutable borrows?

Foo can be modified using the method .modify(): struct Foo; impl Foo { fn modify(&mut self) {} } Bar ... a similar guarantee for item 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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1.0k views

1 answer

rust - How do I create a random String by sampling from alphanumeric characters?

I tried to compile the following code: extern crate rand; // 0.6 use rand::Rng; fn main() { rand::thread_rng ... How can I go further from here? See Question&Answers more detail:os...

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

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