rust - 因为我可以使向量在结构内部可变

Question

因为我可以使向量可变

pub struct Test<'a>{
    vec: &'a mut Vec<i32>,
}
impl<'a> Test<'a> {
    pub fn created()->Test<'a>{
        Test {vec: &'a mut Vec::new() }
    }
    pub fn add(&self, value: i32){  
        self.vec.push(value);
    }
}

---

expected `:`, found `mut`
Test {vec: &'a mut Vec::new() }
               ^~~

这是一个 similar question但是

答案有效，但如果我不想要怎么办，您可以这样做，“应用响应链接”

pub struct Test{
    vec: Vec<i32>,
}
impl Test {
    pub fn created()->Test {
        Test {vec: Vec::new() }
    }
    pub fn add(&mut self, value: i32){  
        self.vec.push(value);
    }
}
..//
let mut test: my::Test = my::Test::created();
test.add(1i32);

let mut test1: my::Test = my::Test::created();

test1 = test; <-- I do not want, you can do this
..//

因为我可以使向量可变，而无需将其全部设为结构

Answer 1

也许您正在寻找interior mutability .请不要随意使用内部可变性，请阅读 this首先。

use std::cell::RefCell;

pub struct Test{
    vec: RefCell<Vec<i32>>,
}

impl Test {
    pub fn created()->Test {
        Test {vec: RefCell::new(Vec::new()) }
    }
    pub fn add(&self, value: i32){  
        self.vec.borrow_mut().push(value);
    }
}

fn main() {
    let test = Test::created();
    test.add(1i32);

    let test1 = Test::created();
    // test1 = test; // does not work anymore
}