Rustlings: enums2.rs #Issue33 — Enums in Rust
Rustlings Challenge: enums2.rs Solution Walkthrough
This is the thirty-third (33rd) issue of the Rustlings series. In this issue, we provide solutions to Rustlings exercises along with detailed explanations. In this issue we will solve the challenge on enums2.rs.
Previous challenge #Issue 32
Rust allows you to define types called “enums” which enumerate possible values. Enums are a feature in many languages, but their capabilities differ in each language. Rust’s enums are most similar to algebraic data types in functional languages, such as F#, OCaml, and Haskell. Useful in combination with enums is Rust’s “pattern matching” facility, which makes it easy to run different code for different values of an enumeration.
Challenge:
// enums2.rs
//
// Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
// hint.
// I AM NOT DONE
#[derive(Debug)]
enum Message {
// TODO: define the different variants used below
}
impl Message {
fn call(&self) {
println!("{:?}", self);
}
}
fn main() {
let messages = [
Message::Move { x: 10, y: 30 },
Message::Echo(String::from("hello world")),
Message::ChangeColor(200, 255, 255),
Message::Quit,
];
for message in &messages {
message.call();
}
}If you run the code on your editor, the compiler will throw the error:
Compiling playground v0.0.1 (/playground)
error[E0599]: no variant named `Move` found for enum `Message`
--> src/main.rs:21:18
|
9 | enum Message {
| ------------ variant `Move` not found here
...
21 | Message::Move { x: 10, y: 30 },
| ^^^^ variant not found in `Message`
error[E0599]: no variant or associated item named `Echo` found for enum `Message` in the current scope
--> src/main.rs:22:18
|
9 | enum Message {
| ------------ variant or associated item `Echo` not found for this enum
...
22 | Message::Echo(String::from("hello world")),
| ^^^^ variant or associated item not found in `Message`
error[E0599]: no variant or associated item named `ChangeColor` found for enum `Message` in the current scope
--> src/main.rs:23:18
|
9 | enum Message {
| ------------ variant or associated item `ChangeColor` not found for this enum
...
23 | Message::ChangeColor(200, 255, 255),
| ^^^^^^^^^^^ variant or associated item not found in `Message`Explanation:
In the challenge enums1.rs, the task was to define an enum named Message with several variants, such as Quit, Echo, Move, and ChangeColor. The key takeaway from this challenge is understanding how to create enums in Rust and define different variants.
In the challenge enums2.rs, we are needed to define variants for the Message enum, each with specific associated data types. This exercise demonstrates how to use enums to represent different types of messages or data in your Rust programs. It also introduced the concept of implementing methods for enums, making them more versatile and capable of performing actions.
Solution:
#[derive(Debug)]
enum Message {
// TODO: define the different variants used below
Move{x:u32,y:u32},
Echo(String),
ChangeColor(u32,u32,u32),
Quit,
}
impl Message {
fn call(&self) {
println!("{:?}", self);
}
}
fn main() {
let messages = [
Message::Move { x: 10, y: 30 },
Message::Echo(String::from("hello world")),
Message::ChangeColor(200, 255, 255),
Message::Quit,
];
for message in &messages {
message.call();
}
}Overall, these challenges highlight the power of enums in Rust for creating custom types with distinct variants and associated data, which can be useful for modeling various scenarios in your code.
You can experiment with the code on Rust Playground.
Resources
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Thank you, and we look forward to seeing you for the next challenges!
