RefCell - Rust Programming

RefCell<T> checks Rust's borrow rules while the program runs, allowing mutation through a shared owner when the borrowing pattern is valid.

Program

Play the program to choose a log item and push it into a vector stored inside RefCell.

refcell_buffer.rs

use std::cell::RefCell;

fn main() {
    let item = ;
    let log = RefCell::new(Vec::new());
    log.borrow_mut().push("start");
    log.borrow_mut().push(item);
    let count = log.borrow().len();
    println!("{count}");
}

use std::cell::RefCell;

fn main() {
    let item = ;
    let log = RefCell::new(Vec::new());
    log.borrow_mut().push("start");
    log.borrow_mut().push(item);
    let count = log.borrow().len();
    println!("{count}");
}

use std::cell::RefCell;

fn main() {
    let item = ;
    let log = RefCell::new(Vec::new());
    log.borrow_mut().push("start");
    log.borrow_mut().push(item);
    let count = log.borrow().len();
    println!("{count}");
}

RefCell<T> `RefCell<T>` moves borrow checking for the wrapped value to runtime.

borrow_mut `borrow_mut` grants a temporary mutable borrow when no conflicting borrow exists.

borrow `borrow` grants a temporary shared borrow for reading.