How to compare enum without pattern matching

Question

I want to apply filter on an iterator and I came up with this one and it works, but it\'s super verbose:

.filter(|ref my_struct| match my_struct         


        

Answer 1

I'd use pattern matching, but I'd move it to a method on the enum so that the filter closure is tidier:

#[derive(Debug)]
enum Thing {
    One(i32),
    Two(String),
    Unknown,
}

impl Thing {
    fn is_unknown(&self) -> bool {
        match *self {
            Thing::Unknown => true,
            _ => false,
        }
    }
}

fn main() {
    let things = vec![Thing::One(42), Thing::Two("hello".into()), Thing::Unknown];
    for t in things.iter().filter(|s| !s.is_unknown()) {
        println!("{:?}", t);
    }
}

See also:

• Compare enums only by variant, not value