Decorator

Decorator in Rust

Decorator is a structural pattern that allows adding new behaviors to objects dynamically by placing them inside special wrapper objects, called decorators.

Using decorators you can wrap objects countless number of times since both target objects and decorators follow the same interface. The resulting object will get a stacking behavior of all wrappers.

Learn more about Decorator

Input streams decoration

There is a practical example in Rust’s standard library for input/output operations.

A buffered reader decorates a vector reader adding buffered behavior.

let mut input = BufReader::new(Cursor::new("Input data"));
input.read(&mut buf).ok();

main.rs

use std::io::{BufReader, Cursor, Read};

fn main() {
    let mut buf = [0u8; 10];

    // A buffered reader decorates a vector reader which wraps input data.
    let mut input = BufReader::new(Cursor::new("Input data"));

    input.read(&mut buf).ok();

    print!("Read from a buffered reader: ");

    for byte in buf {
        print!("{}", char::from(byte));
    }

    println!();
}

Output

Read from a buffered reader: Input data

Decorator in Other Languages