Recent questions tagged Rust

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rust - Why can I call File.take() on a reference?

When I look at File's docs, I see that the take method takes a self, not a &self. But I'm still able to call ... here? (using rustc 1.3.0-dev) See Question&Answers more detail:os...

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

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909 views

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rust - Extending borrowed lifetime for String slice

I have a function that reads in a file, and for each line adds it to a HashSet of type &str, but I can't ... I want to keep it around longer? 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 - How to unwrap a &Result<_,_>?

What is a good way to extract data from a &Result type? In my specific case, I have a &Result<DirEntry, Error> ... :Error> : std::clone::Clone` See Question&Answers more detail:os...

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

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973 views

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rust - Concurrent access to vector from multiple threads using a mutex lock

I'm using an example provided by the Tokio library and attempting to have a vector of all the currently ... without writing any unsafe 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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935 views

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rust - Why can't I assign one dereference of a reference of a reference to another when the outer lifetimes differ?

I want to write the following function: fn foo<'a, 'b, 'c>(rr1: &'a mut &'c mut u32, rr2: &'b mut ... way instead of the way I thought they 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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949 views

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rust - How do I return an iterator that has a reference to something inside a RefCell?

I'm trying to create a method that returns an iterator over the values of HashMap that is boxed inside a RefCell, ... or is there a better 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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833 views

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rust - Is it safe to logically split a borrow to work around a limitation of the NLL-enabled borrow-checker?

The following code involves a very subtle bit of borrow checker dodging. The code itself describes the reasoning ... mutable borrow occurs 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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822 views

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rust - Collaterally moved error when deconstructing a Box of pairs

The following two lines: let x = Box::new(("slefj".to_string(), "a".to_string())); let (a, b) = ... I'm pattern matching deep into a structure. See Question&Answers more detail:os...

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

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934 views

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rust - Defining a method for a struct only when a field is a certain enum variant?

I have the following struct: #[derive(Debug)] pub struct Entry { pub index: usize, pub name: String, pub ... of anything like that in Rust. 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 - How to access current cargo profile (build, test, bench, doc, ....) from the build script (build.rs)

I want to write a custom build.rs script that generates some diagrams to accompany the documentation for a crate I'm ... "debug" or "release". 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 - Can I add a dependent crate that is a subdirectory in a git repository?

I want to use an EDN parser but it is inside https://github.com/mozilla/mentat. https://github.com/ ... this crate inside the mentat repository? 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 it possible to return a mutable reference to a literal from a function?

The current edition of The Rustonomicon has this example code: use std::mem; pub struct IterMut<'a, T: ' ... is about returning a 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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977 views

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rust - How do I share a HashMap between Hyper handlers?

I'm attempting to learn Rust by implementing a simple in-memory URL shortener with Hyper 0.10. I'm running ... message is very cryptic to 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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864 views

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rust - How do I implement the Chain of Responsibility pattern using a chain of trait objects?

I'm trying to implement the Chain of Responsibility design pattern in Rust: pub trait Policeman<'a> { fn ... of Responsibility pattern in Rust? 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 do I implement FromStr with a concrete lifetime?

I want to implement FromStr for a struct with a lifetime parameter: use std::str::FromStr; struct Foo<'a> { bar: &'a ... 'a>, ()> { | ^ Playpen 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 - Why must the associated type be specified in a collection of trait object references?

Here is an offending example (Playground): // Some traits trait Behaviour { type Sub: SubBehaviour; } trait ... get this code to work? See Question&Answers more detail:os...

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

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869 views

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rust - Why does the compiler claim that an associated type from a higher-ranked trait bound doesn't implement `Display` even though it should?

I'm building a library that implements string joins; that is, printing all the elements of a container ... through deref coercion, 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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1.1k views

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rust - Why does a for loop not require a mutable iterator?

If I want to consume an iterator by hand, it has to be mutable: let test = vec![1, 2, 3]; let mut ... right? Is there more to be explained? See Question&Answers more detail:os...

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

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934 views

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rust - Why can't `Self` be used to refer to an enum's variant in a method body?

This question is now obsolete because this feature has been implemented. Related answer. The following Rust code ... type implements the trait. 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

1 answer

rust - Requiring a trait bound on the associated type of an inherited trait

I have a trait Foo inheriting from another trait Bar. Bar has an associated type Baz. Foo constrains Baz such ... recommended way to do 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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1.3k views

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rust - What must I cast an `u8` to in able to use it as an index in my vector?

I have a 2D vector in Rust which I am trying to index with a dynamic u8 variable. An example of what I'm ... it as an index in my vector? 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 - Why do proc-macros have to be defined in proc-macro crate?

I was trying to create a derive macro for my trait, to simplify some stuff. I've encountered some problems: ... the reason for this behavior? See Question&Answers more detail:os...

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

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1.4k views

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rust - How to implement PartialEq for an enum?

I have the following definition: enum Either<T, U> { Left(T), Right(U), } How would I get the ... ^^ cannot move out of borrowed content 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 - How to make a compiled Regexp a global variable?

I have several regular expressions that are defined at runtime and I would like to make them global variables. To ... another way to do 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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1.1k views

1 answer

rust - Deserialize a Vec<Foobar<T>> as Vec<T> directly when Foobar has exactly one field

I'm given a data-format that includes a sequence of objects with exactly one named field value each. ... still using it using deserialization? See Question&Answers more detail:os...

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

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952 views

1 answer

rust - What is the difference between type casting by setting the type of a variable and using `as`?

What is the difference between these two cases? Why does the commented line compile but the last line in the main ... collect() as String ); } See Question&Answers more detail:os...

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

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746 views

1 answer

rust - Why does the address of an object change across methods?

I have C code to bridge to. I chose to use mem::uninitialized to claim the memory first, then call ... do something user addr: 0x7fff5b948ba0 See Question&Answers more detail:os...

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

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1.0k views

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rust - Can struct-like enums be used as types?

Consider the following (illegal) example: enum Foo { Bar { i: i32 }, Baz, } struct MyStruct { field: Foo:: ... struct MyStruct { field: Bar, } See Question&Answers more detail:os...

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

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