Field Shorthand Syntax

If you already have variables with the right names, then you can create the struct using a shorthand:

#[derive(Debug)]
struct Person {
    name: String,
    age: u8,
}

impl Person {
    fn new(name: String, age: u8) -> Person {
        Person { name, age }
    }
}

fn main() {
    let peter = Person::new(String::from("Peter"), 27);
    println!("{peter:?}");
}

  • The new function could be written using Self as a type, as it is interchangeable with the struct type name

    #[derive(Debug)]
struct Person {
    name: String,
    age: u8,
}
impl Person {
    fn new(name: String, age: u8) -> Self {
        Self { name, age }
    }
}

  • Implement the Default trait for the struct. Define some fields and use the default values for the other fields.

    #[derive(Debug)]
struct Person {
    name: String,
    age: u8,
}
impl Default for Person {
    fn default() -> Person {
        Person {
            name: "Bot".to_string(),
            age: 0,
        }
    }
}
fn create_default() {
    let tmp = Person {
        ..Person::default()
    };
    let tmp = Person {
        name: "Sam".to_string(),
        ..Person::default()
    };
}

  • Methods are defined in the impl block.

  • Use struct update syntax to define a new structure using peter. Note that the variable peter will no longer be accessible afterwards.

  • Use {:#?} when printing structs to request the Debug representation.