comprehensive-rust/src/structs/field-shorthand.md

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 {
          ..Default::default()
      };
      let tmp = Person {
          name: "Sam".to_string(),
          ..Default::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.