Removing elements from a Vec based on some condition

Question

My code looks like this:

struct Bar {
    i: i32,
}

struct Foo {
    v: Vec,
}

impl Foo {
    fn foo(&mut self) {
        self.v.drain(self.         


        

Answer 1

In nightly Rust, you can use Vec::drain_filter:

#![feature(drain_filter)]

#[derive(Debug)]
struct Bar {
    i: i32,
}

fn main() {
    let mut bars = vec![Bar { i: 1 }, Bar { i: 10 }, Bar { i: 3 }, Bar { i: 100 }];
    bars.drain_filter(|b| b.i < 10);
    println!("{:?}", bars);
}

What's extra interesting about drain_filter is that you can get the rejected values as it returns an iterator of them:

let rejects: Vec<_> = bars.drain_filter(|b| b.i < 10).collect();

You can also choose to modify the value being iterated over:

bars.drain_filter(|b| {
    b.i -= 1;
    b.i < 10
});