Default function arguments in Rust

Question

Is it possible in Rust to create a function with a default argument?

fn add(a: int = 1, b: int = 2) { a + b }

Answer 1

Another way could be to declare an enum with the optional params as variants, which can be parameterized to take the right type for each option. The function can be implemented to take a variable length slice of the enum variants. They can be in any order and length. The defaults are implemented within the function as initial assignments.

enum FooOptions<'a> {
    Height(f64),
    Weight(f64),
    Name(&'a str),
}
use FooOptions::*;

fn foo(args: &[FooOptions]) {
    let mut height   = 1.8;
    let mut weight   = 77.11;
    let mut name     = "unspecified".to_string();

    for opt in args {
        match opt {
            Height(h) => height = *h,
            Weight(w) => weight = *w,
            Name(n)   => name   =  n.to_string(),
        }
    }
    println!("  name: {}\nweight: {} kg\nheight: {} m", 
             name, weight, height);
}

fn main() { 

            foo( &[ Weight(90.0), Name("Bob") ] );

}

output:

  name: Bob
weight: 90 kg
height: 1.8 m