How to Use Extension Traits in Rust

Extension traits let you add methods to types you don't own by defining a trait and implementing it for that type. You define the trait with the desired methods, then implement it for the external type, allowing you to call those methods as if they were native.

trait MyExtension {
    fn my_method(&self);
}

impl MyExtension for String {
    fn my_method(&self) {
        println!("Extended: {}", self);
    }
}

fn main() {
    let s = String::from("Hello");
    s.my_method();
}

Extension traits let you add new functionality to existing types without changing their original code. Think of it like adding a new tool to a toolbox; the toolbox itself doesn't change, but now you have more things you can do with it. This is useful when you need to extend libraries or standard types with custom behavior.