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Questions tagged [refcell]

64 questions
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Peekable content is None after refactor the code

I have this method: fn parse_http_request_headers<'b>(sp: &'b mut std::str::Split<&str>) -> HashMap { let mut headers: HashMap = HashMap::new(); let mut iter = sp.peekable(); while iter.peek()…
Alex Vergara
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Pattern matching a mutable Rc> without a method

Suppose I have the following code: enum Foo { X { x: i32 }, Y { y: String }, } // Change x value if foo is X, otherwise do nothing. fn test(foo: Rc>) { panic!("help!") } How do I implement test? I know I can implement it…
Gal
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rust two objects refering each borrow_mut pattern

A similar question I posted earlier is here Rust can't modify RefCell in Rc, but completely different. I want to simulate some natural process, so I have a Simulator, and a reactor like a NuclearReactor. The simulator will modify the reactor, and…
YNX
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Returning iterator from weak references for mapping and modifying values

I'm trying quite complex stuff with Rust where I need the following attributes, and am fighting the compiler. Object which itself lives from start to finish of application, however, where internal maps/vectors could be modified during application…
tradinggy
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Implement Borrow on something behind a RefCell?

I have the structs Value and RefValue in my project. RefValue is a reference-counted, dynamically borrowable Value. Now Value may contain a HashMap of RefValue, where both the key and the value is a RefValue. type ValueMap = HashMap
glasflügel
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Rust - storing a temporary "context" - lifetimes vs smart pointers

I am trying to learn Rust, specifically lifetimes and smart pointers and would like to know the most Rusty way of doing this. Specifically, assume we are designing a mock language and "analyzer": a=1 # each line is of form name=number|name b=2 c=a #…
Megh Parikh
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refcell rc> doesn't change

Here is my simplified code. I need to change the pdp_state in a function. but the state remain 'a'. I don't figure out why cloning Rc does not work. I also checked this cloning out side a structure an it worked. #[derive(Clone,Copy)] enum…
Farbod PM
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Access two mutable references from a Global hashmap at once in Rust

Say we have a globally accessible hashmap of trait objects we make with lazy_static: MY_ANIMALS: Mutex>, where type AnimalBox = Box Now, we want the animals in this global hashmap to interact with each…
ANimator120
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How can I modify a reference to a field within the same struct using Rc and RefCell?

I have a struct with a field that references the current element on an array in the same struct using Rc. I can now have a reference to any element from then nums field: use std::{cell::RefCell, rc::Rc}; struct ArrayTest { nums: [u32; 8], …
user12513149
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Is RefCell an appropriate workaround to borrow two mutable elements from a vector?

Consider this toy example of "fighting" two random "players": #[derive(Clone)] struct Player { name: String, health: i32, attack: i32, } fn fight(player_a: &mut Player, player_b: &mut Player) { player_a.health -= player_b.attack; …
t_d_milan
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Rust panics when I inline borrow on RefCell<>

When I run the following line in a function, Rust panics. X is &Tree and Tree is Rc>>. TreeNode is a struct. x.borrow_mut().parent.as_ref().unwrap().borrow_mut().left = Option::from(y.as_ref().unwrap().clone()); I tried changing…
Jay
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"cannot return value referencing temporary value" and interior mutability in Rust

I have the following code in Rust: pub struct RegExpFilter { ... regexp_data: RefCell>, ... } struct RegexpData { regexp: regex::Regex, string: String } ... pub fn is_regexp_compiled(&self) -> bool { …
4ntoine
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Passing around a reference to a struct in Rust

My problem basically is that in my program I need to pass around the reference to the s struct to multiple places including a new thread. In C I could for example declare it a a global struct and use it that way. How can I do this in rust? I also…
Andrzej C
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How to create a value with reference-counted references to itself while checking an already-borrowed field?

I'm trying to create a mutable structure B which stores instances of other structure A that hold references to B. I want an implementation such that any mutation done to the original B propagates to the references held in the As. However, during the…
DrunkCoder
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Error borrowing content while rewriting a function to use traits

I'm new to Rust and toy with the language a little bit. I wrote two simple functions that increment and decrements a value inside Rc>. Since this functionality makes sense for any number type, I tried to turn them into generic…
Natjo
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