bon 2.0.0

bon is a Rust crate for generating compile-time-checked builders for functions and structs.

Visit the guide for a complete overview of the crate.

Quick examples

bon can turn a function with positional parameters into a function with "named" parameters via a builder. It's as easy as placing the #[builder] attribute on top of it.

use bon::builder;

#[builder]
fn greet(name: &str, age: u32) -> String {
    format!("Hello {name} with age {age}!")
}

let greeting = greet()
    .name("Bon")
    .age(24)
    .call();

assert_eq!(greeting, "Hello Bon with age 24!");

You can also use the #[builder] attribute with structs and associated methods:

use bon::{bon, builder};

#[builder]
struct User {
    id: u32,
    name: String,
}

#[bon]
impl User {
    #[builder]
    fn greet(&self, target: &str, level: Option<&str>) -> String {
        let level = level.unwrap_or("INFO");
        let name = &self.name;

        format!("[{level}] {name} says hello to {target}")
    }
}

let user = User::builder()
    .id(1)
    .name("Bon".to_owned())
    .build();

let greeting = user
    .greet()
    .target("the world")
    // `level` is optional, we can omit it here
    .call();

assert_eq!(user.id, 1);
assert_eq!(user.name, "Bon");
assert_eq!(greeting, "[INFO] Bon says hello to the world");

See the guide for the rest.

If you like the idea of this crate and want to say "thank you" or "keep doing this" consider giving us a star ⭐ on Github. Any support and contribution are appreciated 🐱!

Quick examples

License