Understanding Rust’s From Trait

In Rust, the From trait plays a crucial role in allowing the conversion of one type into another. Let’s explore this concept through a straightforward example involving the conversion of lengths from feet to meters.

Struct Definitions

// Define a simple struct named `Feet` to represent a length in feet.
struct Feet {
    value: f64,

// Define another struct named `Meters` to represent a length in meters.
struct Meters {
    value: f64,

Here, we have two structs, Feet and Meters, each representing a length in a different unit.

From Trait Implementation

// Implement the `From` trait to convert from `Feet` to `Meters`.
impl From<Feet> for Meters {
    fn from(feet: Feet) -> Self {
        // Conversion logic: 1 foot is approximately 0.3048 meters.
        let meters_value = feet.value * 0.3048;
        Meters { value: meters_value }

This code snippet shows how we implement the From trait for the conversion from Feet to Meters. The conversion logic is applied in the implementation, making it clear and concise.

Main Function

fn main() {
    // Create an instance of `Feet`.
    let feet_length = Feet { value: 10.0 };

    // Convert the length from `Feet` to `Meters` using the `Into` trait.
    let meters_length: Meters = feet_length.into();

    // Print the result.
    println!("Length in meters: {:.2}", meters_length.value);

In the main function, we showcase the practical usage of the conversion. We create an instance of Feet, convert it to Meters using the into() method, and print the result.

This example serves to illustrate how the From trait facilitates seamless conversions between different types in Rust. It is particularly useful when dealing with scenarios like unit conversions or working with different representations of data.

Rust from trait example - Nice!

Rust – from trait – example code in Rust Playground


Length in meters: 3.05

And finally, there is another way to achieve this using “into” – see the “Learning Rust” video below

Learning Rust – Impl INTO <String>