BurntSushi / advent-of-code

Line 26 in d5e3fe3

let mut claims: Vec<Claim> = vec![];

I think I pretty much always use vec![]. I can't think of any specific instance where I'd want to use Vec::new, unless I wanted to use it as a function value. e.g., if you have

fn build_a_vec(build: impl Fn() -> Vec<i32>) {
    let vector = build();
    // do something with vector
}

fn main() {
    build_a_vec(Vec::new);
}

But even then, that's not code I can remember writing.

I believe the choice between vec![] and Vec::new is almost entirely stylistic. The former is more flexible, so it tends to be what folks use.

Note that in the code you referenced, I did include the type, Vec<Claim>, which I believe is optional in that context. I include the type sometimes to make the code clearer. It's a judgment call. :-)

When to use vec! instead of Vec::new()?