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.
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.
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Licensed under either of Apache License, Version 2.0 or MIT license at your option.Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.