Rust Smart Pointers — Box, Rc, RefCell, and Interior Mutability Patterns

DodaTech Updated 2026-06-28 1 min read

In this tutorial, you will learn about Rust Smart Pointers. We cover key concepts, practical examples, and best practices to help you master this topic.

Rust smart pointers include Box for heap allocation, Rc for reference counting, RefCell for interior mutability, and Cell for copy types.

What You'll Learn

Box for heap allocation
Rc for shared ownership
RefCell for interior mutability
Deref and Drop traits

Why It Matters

Smart pointers enable patterns not possible with basic ownership. DodaZIP uses Box for trait objects and Rc for shared configuration.

Real-World Use

Recursive data structures, graph structures, shared state, plugin trait objects.

use std::rc::Rc;
use std::cell::RefCell;

// Box for heap allocation
fn box_example() {
    let b = Box::new(5);
    println!("b = {}", b);

    // Recursive type needs Box
    #[derive(Debug)]
    enum List {
        Cons(i32, Box<List>),
        Nil,
    }
    let list = List::Cons(1, Box::new(List::Cons(2, Box::new(List::Nil))));
    println!("{:?}", list);
}

// Rc for shared ownership
fn rc_example() {
    let a = Rc::new(5);
    let b = Rc::clone(&a);
    let c = Rc::clone(&a);
    println!("Reference count: {}", Rc::strong_count(&a));
}

// RefCell for interior mutability
fn refcell_example() {
    let value = Rc::new(RefCell::new(5));
    let shared = Rc::clone(&value);

    *value.borrow_mut() += 10;

    println!("Value: {}", shared.borrow());
}

fn main() {
    box_example();
    rc_example();
    refcell_example();
}

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